Control system, method of operating a heating apparatus and controlled heating apparatus

• US 5,235,159 A
• Filed: 08/06/1990
• Issued: 08/10/1993
• Est. Priority Date: 03/25/1988
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Alley, Robert P., Harnden, John D. Jr., Kornrumpf, William P.
• Primary Examiner(s): Paschall, Mark H.
• Application Number:
  US07/562,712
• Time in Patent Office: 1,100 Days
• Field of Search: 219/492, 219/494, 219/501, 219/508-512, 219/519, 219/483-486, 310/330-332
• US Class Current: 219/486
• CPC Class Codes: F24C 15/106 electric circuits
• CPC Class Codes: G05D 23/1909 whose output amplitude can only take two discrete values
• CPC Class Codes: H01H 57/00 Electrostrictive relays; Piezoelectric relays

Abstract

A control system for regulating electrical power input to the resistive heating elements of an electric heating apparatus, including domestic cooking appliances, is provided which employs at least one piezoceramic relay device. The electrical power is applied with the piezoceramic relay device responsive to control signals and with the control circuitry being directly and ohmically connected to the power source. In one embodiment, the control system employs individual piezoceramic relay devices for power regulation to the individual heating elements while in different embodiments a single piezoceramic relay device regulates power input to a pair of the heating elements. A method of operating the controlled apparatus in such manner and an apparatus having such control system are also disclosed.

Claims

1. In a system to regulated electrical power input in an electric heating apparatus utilizing at least one resistive heating element in combination:

(a) a piezoceramic relay device connected in circuit relationship to enable connection of a power source to the heating element, the piezoceramic relay device including a movable polarized piezoceramic bender member and movable electrical contact means which coact with fixed electrical contact means disposed thereby, the piezoceramic bender member maintaining the movable electrical contact means spaced apart from the fixed electrical contact means while the heating element is in an unenergized condition, the movable electrical contact means being connected to an electrically conductive spring element, the bender member and the spring element being operatively connected by an insulating means for common movement, the piezoceramic relay device including clamping means being secured at portions adjacent to and mechanically supporting the bender member and the spring element in a cantilever manner for operating the coacting electrical contact means, and

(b) control circuitry responsive to a power setting selected by an operator, the circuitry being directly and ohmically connected to the piezoceramic relay device, the control circuitry generating control signals for actuation of the movable piezoceramic bender member and causing the bender member to deflect and complete a circuit between the power source and the heating element.

2. The power regulating system of claim 1 wherein the control circuitry responds to a power setting selected by an operator from a plurality of available power settings.

3. The power regulating system of claim 1 wherein the control circuitry is made further responsive to control signals derived with temperature sensing means.

4. The power regulating system of claim 3 wherein the temperature achieved when the heating element is operated is determined with temperature feedback control means.

5. The power regulating system of claim 4 wherein the temperature feedback control means derives an error signal which is the function of the difference between the sensed temperature and a predetermined temperature setting.

6. The power regulating system of claim 5 wherein the predetermined temperature setting is selected by an operator from a plurality of available temperature settings.

7. The power regulating system of claim 1 wherein the piezoceramic bender member is formed by at least two planar prepoled piezoceramic plate elements secured in opposed parallel relationship sandwich fashion on opposite sides of at least one central conductive surface and having outer conductive surfaces that are insulated from each other and the central conductive surface by the respective intervening piezoceramic plate element thicknesses.

8. The power regulating system of claim 1 wherein the control circuitry includes additional switching means also responsive to a power setting selected by an operator which interrupt power being supplied to the heating element.

9. The power regulating system of claim 1 wherein the control circuitry further includes a diode-capacitor network for developing a high voltage DC energizing potential to actuate the piezoceramic relay device.

10. The power regulating system of claim 7 wherein the energizing potential to actuate the piezoceramic relay device has the same polarity as the polarity of the potential used to initially polarize the piezoceramic bender member.

11. In a system to regulate electric power input in an electric heating apparatus having a surface cooking mechanism which employs at least one resistive heating element, the combination comprising:

(a) a piezoceramic relay device connected in circuit relationship to enable connection of a power source to the heating element, the piezoceramic relay device including a movable polarized piezoceramic bender member and movable electrical contact means which coact with fixed electrical contact means disposed thereby, the piezoceramic bender member maintaining the movable electrical contact means spaced apart from the fixed electrical contact means while the heating element is in an unenergized condition, the movable electrical contact means being connected to an electrically conductive spring element, the bender member and the spring element being operatively connected by an insulating means for common movement, the piezoceramic relay device including clamping means being secured at portions adjacent to and mechanically supporting the bender member and the spring element in a cantilever manner for operating the coacting electrical contact means, and

(b) control circuitry responsive to a power setting selected by an operator and temperature control signals, the circuitry being directly and ohmically connected to the piezoceramic relay device, the control circuitry causing the bender member to deflect and complete a circuit between the power source and the heating element.

12. The power regulating system of claim 11 wherein the control circuitry responds to a power setting selected by an operator from a plurality of available power settings.

13. The power regulating system of claim 11 wherein the temperature achieved when the heating element is operated is determined with temperature feedback control means.

14. The power regulating system of claim 13 wherein the temperature feedback control means derives an error signal which is the function of the difference between the sensed temperature and a predetermined temperature setting.

15. The power regulating system of claim 14 wherein the predetermined temperature setting is selected by an operator from a plurality of available temperature settings.

16. The power regulating system of claim 11 wherein the piezoceramic bender member is formed by at least two planar prepoled piezoceramic plate elements secured in opposed parallel relationship sandwich fashion on opposite sides of at least one central conductive surface and having outer conductive surfaces that are insulated from each other and the central conductive surface by the respective intervening piezoceramic plate element thicknesses.

17. The power regulating system of claim 11 wherein the control circuitry includes additional switching means also responsive to a power setting selected by an operator which interrupt power being supplied to the heating element.

18. The power regulating system of claim 11 wherein the control circuitry further includes a diode-capacitor network for developing a high voltage DC energizing potential to actuate the piezoceramic relay device.

19. In a system to regulate electric power input in an electric heating apparatus having an oven cooking mechanism which employs at least one resistive heating element, the combination comprising:

(a) a piezoceramic relay device connected in circuit relationship to enable connection of a power source to the heating element, the piezoceramic relay device including a movable polarized piezoceramic bender member and movable electrical contact means which coact with fixed electrical contact means disposed thereby, the piezoceramic bender member maintaining the movable electrical contact means spaced apart from the fixed electrical contact means while the heating element is in an unenergized condition, the movable electrical contact means being connected to an electrically conductive spring element, the bender member and the spring element being operatively connected by an insulating means for common movement, the piezoceramic relay device including clamping means being secured at portions adjacent to and mechanically supporting the bender member and the spring element in a cantilever manner for operating the coacting electrical contact means, and

(b) control circuitry responsive to a power setting selected by an operator and temperature control signals, the circuitry being directly and ohmically connected to the piezoceramic relay devices, and causing the bender member to deflect and complete a circuit between the power source and the heating element.

20. The power regulating system of claim 19 wherein the temperature achieved when the heating element is operated is determined with temperature feedback control means.

21. The power regulating system of claim 19 wherein the temperature feedback control means derives an error signal which is the function of the difference between the sensed temperature and a predetermined temperature setting.

22. The power regulating system of claim 21 wherein the predetermined temperature setting is selected by an operator from a plurality of available temperature settings.

23. The power regulating system of claim 19 wherein the piezoceramic bender member is formed by at least two planar prepoled piezoceramic plate elements secured in opposed parallel relationship sandwich fashion on opposite sides of at least one central conductive surface and having outer conductive surfaces that are insulated from each other and the central conductive surface by the respective intervening piezoceramic plate element thicknesses.

24. The power regulating system of claim 19 wherein the control circuitry includes additional switching means also responsive to a power setting selected by an operator which interrupt power being supplied to the heating element.

25. The power regulating system of claim 19 wherein the control circuitry further includes a diode-capacitor network for developing a high voltage DC energizing potential to actuate the piezoceramic relay device.

26. A system for regulating AC power input to at least one resistive heating element in an electrical cooking appliance comprising in combination:

(a) a piezoceramic relay device connected in circuit relationship to enable connection of a power source to the heating element, the piezoceramic relay device including a movable polarized piezoceramic bender member and movable electrical contact means which coact with fixed electrical contact means disposed thereby, the piezoceramic bender member maintaining the movable electrical contact means spaced apart from the fixed electrical contact means while the heating element is in an unenergized condition, the movable electrical contact means being connected to an electrically conductive spring element, the bender member and the spring element being operatively connected by an insulating means for common movement, the piezoceramic relay device including clamping means being secured at portions adjacent to and mechanically supporting the bender member and the spring element in a cantilever manner for operating the coacting electrical contact means,

(b) control circuitry responsive to a power setting selected by an operator and temperature control signals, the circuitry being directly and ohmically connected to the piezoceramic relay device, the control circuitry causing the bender member to deflect and complete a circuit between the AC power source and the heating element, and

(c) the control circuitry providing DC energizing potential for actuation of the bender member with interconnected solid state circuit means.

27. The power regulating system of claim 26 wherein the control circuitry responds to a power setting selected by an operator from a plurality of available power settings.

28. The power regulating system of claim 26 wherein the piezoceramic bender member is selectively prepoled with clamping means being secured at non-poled portions adjacent to and mechanically supporting the selectively prepoled bender member in a cantilever manner for operating the coacting electrical contact means, the non-poled portions being mechanically unstrained and electrically neutral.

29. The power regulating system of claim 26 wherein the piezoceramic bender member is formed by at least two planar prepoled piezoceramic plate elements secured in opposed parallel relationship sandwich fashion on opposite sides of at least one central conductive surface and having outer conductive surfaces that are insulated from each other and the central conductive surface by the respective intervening piezoceramic plate element thicknesses.

30. The power regulating system of claim 29 wherein single movable electrical contact means are provided to the piezoceramic bender member.

31. The power regulating system of claim 29 wherein a pair of movable electrical contact means is provided to the piezoceramic bender member.

32. The power regulating system of claim 26 wherein the temperature achieved when the heating element is operated is determined with temperature feedback control means.

33. The power regulating system of claim 32 wherein the temperature feedback control means derives an error signal which is the function of the difference between the sensed temperature and a predetermined temperature setting.

34. The power regulating system of claim 33 wherein the predetermined temperature setting is selected by an operator from plurality of available temperature settings.

35. The power regulating system of claim 26 wherein the control circuitry includes additional switching means also responsive to a power setting selected by an operator and which interrupt power being supplied to the heating element.

36. The power regulating system of claim 35 wherein the control circuitry cooperates with additional switching means to provide power interruption with respect to both power conductors.

37. The power regulating system of claim 26 wherein the solid state circuit means controls the percentage of time the AC power is applied to the heating element in accordance with the power level setting selected by an operator.

38. The power regulating system of claim 26 wherein the solid state circuit means provides the DC energizing potential to the bender member with a pair of high voltage active devices.

39. The power regulating system of claim 38 wherein the control signals are provided to the high voltage active devices with analog circuit means.

40. The power regulating system of claim 39 wherein the analog circuit means comprises a dual comparator network providing control signals to operate the heating element.

41. The power regulating system of claim 40 wherein the dual comparator network comprises first amplifier means which compares an input DC control voltage with a feedback voltage obtained by modifying its output voltage to charge associated capacitor means and applying the first amplifier output voltage to a second amplifier means for comparison with a saw-tooth reference voltage, the output voltage from the second amplifier means providing actuating signals to the bender member.

42. The power regulating system of claim 41 wherein the control signals operate a pair of heating elements with the control signals operating one heating element being derived with a first sawtooth reference voltage having an inverse relationship with respect to a second sawtooth reference voltage used to derived the control signals operating the other heating element in order to avoid simultaneous power application to the heating elements,

43. The power regulating system of claim 42 wherein the analog circuit means derives the sawtooth reference voltages with unijunction relaxation oscillator means connected in circuit relationship with a pair of series connected feedback amplifier means so that the output from the first amplifier means provides the first sawtooth reference voltage and which upon further being applied to the second amplifier means provides the second sawtooth reference voltage.

44. The power regulating system of claim 26 wherein the control circuitry further includes a safety light source connected in circuit relationship to illuminate whenever the heating element is being operated.

45. A system for regulating power input to at least two resistive heating elements in an electrical heating apparatus comprising in combination:

(a) at least two piezoceramic relay devices connected in circuit relationship to enable individual connection of a power source to either heating element, each piezoceramic relay device having a movable piezoceramic bender element connected to the power source, each of the bender elements having movable electrical contact means which coast with fixed electrical contact means disposed thereby, the fixed and movable electrical contact means of each relay device being separately connected to each heating element, and with each of the bender elements maintaining the movable electrical contact means spaced apart from the fixed electrical contact means while the heating elements are in an unenergized condition, the movable electrical contact means being connected to an electrically conductive spring element, the bender member and the spring element being operatively connected by an insulating means for common movement, the piezoceramic relay device including clamping means being secured at portions adjacent to and mechanically supporting the bender member and the spring element in a cantilever manner for operating the coacting electrical contact means,

(b) control circuitry directly and ohmically connected to each said relay device, the control circuitry responding to a power setting selected by an operator for separate actuation of the individual bender elements and causing the actuated bender element to deflect and complete a circuit between the power source and the heating element operatively associated with the actuated bender element.

46. The power regulating system of claim 45 wherein the control circuitry responds to a power setting selected by an operator from a plurality of available power settings.

47. The power regulating system of claim 45 wherein the control circuitry is made further responsive to control signals derived with temperature sensing means.

48. The power regulating system of claim 47 wherein the temperature achieved when the heating elements are operated is determined with temperature feedback control means.

49. The power regulating system of claim 48 wherein the temperature feedback control means derives an error signal which is the function of the difference between the sensed temperature and a predetermined temperature setting.

50. The power regulating system of claim 49 wherein the predetermined temperature setting is selected by an operator from a plurality of available temperature settings.

51. The power regulating system of claim 45 wherein the piezoceramic bender member is formed by at least two planar prepoled piezoceramic plate elements secured in opposed parallel relationship sandwich fashion on opposite sides of at least one central conductive surface and having outer conductive surfaces that are insulated from each other and the central conductive surface by the respective intervening piezoceramic plate element thicknesses.

52. The power regulating system of claim 45 wherein the control circuitry includes additional switching means also responsive to a power setting selected by an operator which interrupt power being supplied to the heating elements.

53. The power regulating system of claim 45 wherein the control circuitry further includes a diode-capacitor network for developing a high voltage DC energizing potential to actuate the piezoceramic relay device.

54. The power regulating system of claim 51 wherein the energizing potential to actuate the piezoceramic relay device has the same polarity as the polarity of the potential used to initially polarize the piezoceramic bender member.

55. A system for regulating AC power input to a pair of heating elements in a household electrical cooking appliance comprising in combination:

(a) a pair of piezoceramic relay devices connected in circuit relationship to enable individual connection of a power source to either heating element, each piezoceramic relay device having a movable polarized piezoceramic bender element and a movable piezoceramic bender contact means which coact with fixed electrical contact means disposed thereby, each of the bender elements maintaining the movable electrical contact means spaced apart from the fixed electrical contact means while the heating elements are in an unenergized condition, the movable electrical contact means being connected to an electrical conductive spring element, the bender member and the spring element being operatively connected by an insulating means for common movement, the piezoceramic relay device including clamping means being secured at portions adjacent to and mechanically supporting the bender member and the spring element in a cantilever manner for operating the coacting electrical contact means,

(b) control circuitry directly and ohmically connected to each of the piezoceramic relay device which responds to a power setting selected by an operator and temperature control means for separate actuation of the individual bender elements and causes the actuated bender element to deflect and complete a circuit between the AC power source and the heating element operatively associated with the actuated bender element, and

(c) the control circuitry providing DC energizing potential for such separate actuation of the individual bender elements with interconnected analog circuit means which employs a first dual comparator network providing the control signals to operate one heating element as derived with a first sawtooth reference voltage and a second dual comparator network providing the control signals to operate the other heating element as derived with a second sawtooth reference voltage having an inverse relationship with respect to the first sawtooth reference voltage.

56. The power regulating system of claim 55 wherein each dual comparator network comprises first amplifier means which compares an input DC control voltage with a feedback voltage obtained by modifying its output voltage to charge associated capacitor means and applying the first amplifier output voltage to a second amplifier means for comparison with the sawtooth reference voltage, the output voltage from the second amplifier means providing actuating signals to a pair of high voltage active devices connected in control circuitry in control circuitry to apply the DC energizing potential to each bender member.

57. The power regulating system of claim 56 wherein the analog circuit means derives the sawtooth reference voltages with unijunction relaxation oscillator means connected in circuit relationship with a pair of series connected feedback amplifier means so that the output from the first amplifier means provides the first sawtooth reference and which upon further being applied to the second amplifier means provides the second sawtooth reference voltage.

58. The power regulating system of claim 55 wherein the control circuitry further includes a safety light source connected in circuit relationship to illuminate whenever either heating element is being operated.

59. The power regulating system of claim 55 wherein the temperature control signals are derived in the control circuitry with solid state thermistor means.

60. A system for regulating the AC power input to a pair of resistive heating elements in a household electrical cooking appliance comprising in combination:

(a) a pair of piezoceramic relay devices connected in circuit relationship to enable independent connection of a power source to an individual heating element, each of the piezoceramic relay devices including a movable polarized piezoceramic bender member and movable electrical contact means which coact with fixed electrical contact means disposed thereby to connect to one heating element, and with the other piezoceramic relay device including a movable polarized piezoceramic bender member having movable contact means which coact with fixed electrical contact means disposed thereby to connect with the other heating element, each movable electrical contact means being connected to a electrically conductive spring element, the bender member and the spring element being operatively connected by an insulating means for common movement, the piezoceramic relay device including clamping means being secured at portions adjacent to and mechanically supporting the bender member and the spring element in a cantilever manner for operating the coacting electrical contact means,

(b) control circuitry directly and ohmically connected to both piezoceramic relay devices which responds to a power setting selected by an operator and temperature control means for separate actuation of the individual bender members and causes the actuated bender member to deflect and complete a circuit between the AC power source and the heating element operatively associated with the actuated bender member, and

(c) the control circuitry providing DC energizing potential for such separate actuation of the individual relay devices with interconnected analog circuit means which employs a first dual comparator network providing the control signals to operate one heating element as derived with a first sawtooth reference voltage and a second dual comparator network providing the control signals to operate the other heating element as derived with a second sawtooth reference voltage having an inverse relationship with respect to the first sawtooth reference voltage.

61. The power regulating system of claim 60 wherein each dual comparator network comprises first amplifier means which compares an input DC control voltage with a feedback voltage obtained by modifying its output voltage to charge associated capacitor means and applying the first amplifier output voltage to a second amplifier means for comparison with the sawtooth reference voltage, the output voltage from the second amplifier means providing actuating signals to a pair of high voltage active devices connected to apply the DC energizing potential to each bender member.

62. The power regulating system of claim 61 wherein the analog circuit means derives the sawtooth reference voltages with unijunction relaxation oscillator means connected in circuit relationship with a pair of series connected feedback amplifier means so that the output from the first amplifier means provides the first sawtooth reference and which upon further being applied to the second amplifier means provides the second sawtooth reference voltage.

63. The power regulating system of claim 60 wherein the control circuitry further includes a safety light source connected in circuit relationship to illuminate whenever either heating element is being operated.

64. The power regulating system of claim 60 wherein the temperature control signals are derived in the control circuitry with solid state thermistor means.

65. An electric range employing at least one resistive heating element comprising in combination:

(a) power setting selector means enabling an operator to select the desired power level of operation for the heating element,

(b) temperature control means,

(c) a piezoceramic relay device connected in circuit relationship to enable connection of a power source to the heating element, the piezoceramic relay device including a movable polarized piezoceramic bender member and movable electrical contact means which coact with fixed electrical contact means disposed thereby, the piezoceramic bender member maintaining the movable electrical contact means spaced apart from the fixed electrical contact means while the heating element is in an unenergized condition, the movable electrical contact means being connected to an electrically conductive spring element, the bender member and the spring element being operatively connected by an insulating means for common movement, the piezoceramic relay device including clamping means being secured at portions adjacent to and mechanically supporting the bender member and the spring element in a cantilever manner for operating the coacting electrical contact means, and

(d) control circuitry responsive to a power setting selected by an operator and temperature control signals, the circuitry being directly and ohmically connected to the piezoceramic relay device, and causing the piezoceramic bender member to deflect and complete a circuit between the power source and the heating element.

66. The electric range of claim 65 wherein the control circuitry further regulates the percentage of time electrical power is applied to the heating element.

67. The electrical range of claim 65 wherein the temperature achieved when the heating element is operated is determined with temperature feedback control means.

68. The electric range of claim 65 wherein the piezoceramic bender member is formed by at least two planar prepoled piezoceramic plate elements secured in opposed parallel relationship sandwich fashion on opposite sides of at least one central conductive surface and having outer conductive surfaces that are insulated from each other and the central conductive surface by the respective intervening piezoceramic plate element thicknesses.

69. The electric range of claim 68 wherein the movable electrical contact means are disposed on at least one of the outer conductive surfaces.

70. The electric range of claim 65 wherein the control circuitry includes user operated switching means also responsive to a power setting selected by an operator which interrupt power being supplied to the heating element.

71. The electric range of claim 65 wherein the control circuitry derives control signals actuating the piezoceramic relay device with interconnected solid state circuit means.

72. The electric range of claim 70 wherein the solid state circuit means provides DC energizing potential to the bender member with a pair of high voltage active devices.

73. The electric range of claim 72 wherein the control signals are provided to the high voltage active devices with analog circuit means.

74. The electric range of claim 73 wherein the analog circuit means comprises a dual comparator network pair providing individual control signals to a pair of heating elements.

75. The electric range of claim 74 wherein each dual comparator network comprises first amplifier means which compares in input DC control voltage with a feedback voltage obtained by modifying its output voltage to charge associated capacitor means and applying the first amplifier output voltage to a second amplifier means for comparison with a sawtooth reference voltage, the output voltage from the second amplifier means providing control signals to each heating element.

76. An electrical range employing at least two resistive heating elements comprising in combination:

(a) power setting selector means enabling an operator to select the desired power level of operation for each heating element,

(b) temperature control means,

(c) a pair of piezoceramic relay devices connected in circuit relationship to enable independent connection of a power source to an individual heating element, one of the piezoceramic relay devices including a movable polarized piezoceramic bender member and movable electrical contact means which coact with fixed electrical contact means disposed thereby to connect the power source with one heating element, with the other piezoceramic relay device including a movable polarized piezoceramic bender member and movable electrical contact means which coact with fixed electrical contact means disposed thereby to connect the power source with the other heating element, each piezoceramic bender member maintaining the movable electrical contact means spaced apart from the fixed electrical contact means while the heating elements are in an unenergized condition, each movable electrical contact means being connected to an electrically conductive spring element, the bender member and the spring element being operatively connected by an insulating means for common movement, the piezoceramic relay device including clamping means being secured at portions adjacent to and mechanically supporting the bender member and the spring element in a cantilever manner for operating the coacting electrical contact means, and

(d) control circuitry directly and ohmically connected to both piezoceramic relay devices which responds to a power setting selected by an operator and temperature control signals for separate actuation of the individual bender members and causes the actuated bender member to deflect and complete a circuit between the power source and the heating element operatively associated with the actuated bender member.

77. The electric range of claim 76 wherein the control circuitry further regulates the percentage of time electrical power is applied to the heating elements.

78. The electric range of claim 76 wherein the temperature achieved when the heating elements are operated is determined with temperature feedback control means.

79. The electric range of claim 76 wherein the piezoceramic bender members are formed by at least two planar prepoled piezoceramic plate elements secured in opposed parallel relationship sandwich fashion on opposite sides of at least one central conductive surface and having outer conductive surfaces that are insulated from each other and the central conductive surface by the respective intervening piezoceramic plate element thicknesses.

80. The electric range of claim 76 wherein the control circuitry includes user operated switching means also responsive to a power setting selected by an operator which interrupt power being supplied to the heating elements.

81. The electric range of claim 76 wherein the control circuitry derives control signals actuating the piezoceramic relay devices with interconnected solid state circuit means.

82. The electric range of claim 81 wherein the solid state circuit means provides DC energizing potential to the bender members with a pair of high voltage active devices.

83. The electric range of claim 82 wherein the control signals are provided to the high voltage active devices with analog circuit means.

84. The electric range of claim 83 wherein the analog circuit means comprise a dual comparator network pair providing control signals for the individual heating elements.

85. The electric range of claim 84 wherein each dual comparator network comprises first amplifier means which compares an input DC control voltage with a feedback voltage obtained by modifying its output voltage to charge associated capacitor means and applying the first amplifier output voltage to a second amplifier means for comparison with a sawtooth reference voltage, the output voltage from the second amplifier means providing control signals to each heating element.

86. An electric range including a plurality of resistive heating elements, power setting selector means enabling an operator to select the desired power level of operation for each heating element, temperature control means, and control means to regulate AC power input to the individual heating elements comprising:

(a) a surface cooking mechanism employing at least one resistive heating element, a piezoceramic relay device connected in circuit relationship to enable connection of an AC power source to the heating element, the piezoceramic relay device including a movable polarized piezoceramic bender member and movable electrical contact means which coact with fixed electrical contact means disposed thereby, the piezoceramic bender member maintaining the movable electrical contact means spaced apart from the fixed electrical contact means while the heating element is in an unenergized condition, the movable electrical contact means being connected to an electrically conductive spring element, the bender member and the spring element being operatively connected by an insulating means for common movement, the piezoceramic relay device including clamping means being secured at portions adjacent to and mechanically supporting the bender member and the spring element in a cantilever manner for operating the coacting electrical contact means,

(b) control circuity operating the piezoceramic relay device in the surface cooking mechanism response to a power setting selected by an operator and temperature control signals, the control circuitry being directly and ohmically connected to the operatively associated piezoceramic relay device, the control circuitry responding to the control signals for actuation of the movable piezoceramic bender member and causes the bender member to deflect and complete a circuit between the power source and the heating element,

(c) an oven cooking mechanism employing at least one second resistive heating element, a second piezoceramic relay device connected in circuit relationship to enable connection of the AC power source to the second heating element, the second piezoceramic relay device including a second movable polarized piezoceramic bender member having second movable electrical contact means which coact with second fixed electrical contact means disposed thereby, the second fixed electrical contact means being connected to the second heating element, and the second piezoceramic bender member maintaining the second movable electrical contact means spaced apart from the second fixed electrical contact means while the second heating element is in an unenergized condition, the second movable electrical contact means being operatively positioned upon a second electrically conductive spring element, the second bender member and the second spring element being operatively connected by a second insulating means for common movement, the second piezoceramic relay device including second clamping means being secured at portions adjacent to and mechanically supporting the second bender member and the second spring element in a cantilever manner for operating the second coacting electrical contact means, and

(d) second control circuity operating the second piezoceramic relay device in the oven cooking mechanism responsive to a power setting selected by an operator and second temperature control signals, the second control circuitry being directly and ohmically connected to the AC power source and the operatively associated second piezoceramic relay device which responds to the second control signals for actuation of the second movable piezoceramic bender member and causes the second bender to deflect and complete a second circuit between the power source and the second heating element.

87. The electric range of claim 86 wherein the control circuitry further regulates the percentage of time electrical power is applied to the heating elements.

88. The electric range of claim 86 wherein the temperature achieved when the heating elements are operated is determined with temperature feedback control means.

89. The electric range of claim 86 wherein the piezoceramic bender members are formed by at least two planar prepoled piezoceramic plate elements secured in opposed parallel relationship sandwich fashion on opposite sides of at least one central conductive surface and having outer conductive surfaces that are insulated from each other and the central conductive surface by the respective intervening piezoceramic plate element thicknesses.

90. The electric range of claim 86 wherein the control circuitry includes user operated switching means also responsive to a power setting selected by an operator which interrupt power being supplied to the heating elements.

91. The electric range of claim 86 wherein the control circuitry derives control signals actuating the piezoceramic relay devices with interconnected solid state circuit means.

92. The electric range of claim 91 wherein the solid state circuit means provides DC energizing potential to the bender members with a pair of high voltage active devices.

93. The electric range of claim 92 wherein the control signals are provided to the high voltage active devices with analog circuit means.

94. The electric range of claim 93 wherein the analog circuit means comprises a dual comparator network providing individual control signals to the heating elements.

95. The electric range of claim 94 wherein the dual comparator network comprises first amplifier means which compares an input DC control voltage with a feedback voltage obtained by modifying its output voltage to charge associated capacitor means and applying the first amplifier output voltage to a second amplifier means for comparison with a sawtooth reference voltage, the output voltage from the second amplifier means providing control signals to an individual heating element.

96. An electric range including a plurality of resistive heating elements, power setting selector means enabling an operator to select the desired power level of operation for each heating element, temperature control means, and control means to regulate an AC power input to the individual heating elements comprising:

(a) a surface cooking mechanism employing at least two resistive heating elements, a plurality of piezoceramic relay devices connected in circuit relationship to enable individual connection of the power source to either heating element, each relay device including a movable polarized piezoceramic bender member and movable contact means which coact with fixed electrical contact means disposed thereby, the piezoceramic bender members each maintaining the respective movable electrical contact means spaced apart from the respective fixed electrical contact means while the heating elements are in an unenergized condition, each movable electrical contact means being connected to an electrically conductive spring element, the bender member and the spring element being operatively connected by an insulating means for common movement, the piezoceramic relay device including clamping means being secured at portions adjacent to and mechanically supporting the bender member and the spring element in a cantilever manner for operating the coacting electrical contact means,

(b) control circuitry operating the piezoceramic relay devices in the surface cooking mechanism responsive to power settings selected by an operator and temperature control signals to cause one of the bender members to deflect and complete a circuit between the power source and one heating element or a second of the bender members to deflect and complete a circuit between the power source and the other heating element,

(c) an oven cooking mechanism employing at least two second resistive heating elements, at least two second piezoceramic relay devices connected in circuit relationship to enable individual connection of the power source to either second heating element, each second relay device including a second movable piezoceramic bender member having second movable contact means which coact with second fixed electrical contact means disposed thereby, the second fixed electrical contact means being connected to each second heating element and the second piezoceramic bender members each maintaining the respective second movable electrical contact means spaced apart from the respective second fixed electrical contact means while the second heating elements are in an unenergized condition, each second movable electrical contact means being connected to a second electrically conductive spring element, the second bender members and the second spring elements being operatively connected by second insulating means for common movement, the second piezoceramic bender members including clamping means being secured at portions adjacent to and mechanically supporting the second bender members and the second spring elements in a cantilever manner for operating the second coacting electrical contact means, and

(d) second control circuitry operating the second piezoceramic relay device in the oven cooking mechanism responsive to a power setting selected by an operator and second temperature control signals to cause one of the second bender members to deflect and complete a second circuit between the power source and one second heating element or a second of the second bender members to deflect and complete a circuit between the power source and the other second heating element.

97. The electric range of claim 96 wherein the control circuitry further regulates the percentage of time electrical power is applied to the heating elements.

98. The electric range of claim 96 wherein the temperature achieved when the heating elements are operated is determined with temperature feedback control means.

99. The electric range of claim 96 wherein the piezoceramic bender members are formed by at least two planar prepoled piezoceramic plate elements secured in opposed parallel relationship sandwich fashion on opposite sides of at least one central conductive surface and having outer conductive surfaces that are insulated from each other and the central conductive surface by the respective intervening piezoceramic plate element thicknesses.

100. The electric range of claim 96 wherein the control circuitry includes user operated switching means also responsive to a power setting selected by an operator which interrupt power being supplied to the heating elements.

101. The electric range of claim 96 wherein the control circuitry derives control signals actuating the piezoceramic relay devices with interconnected solid state circuit means.

102. The electric range of claim 101 wherein the solid state circuit means provides DC energizing potential to the bender members with a pair of high voltage active devices.

103. The electric range of claim 102 wherein the control signals are provided to the high voltage active devices with analog circuit means.

104. The electric range of claim 103 wherein the analog circuit means comprises a dual comparator network pair providing control signals to the individual heating elements.

105. The electric range of claim 104 wherein each dual comparator network comprises first amplifier means which compares an input DC control voltage with a feedback voltage obtained by modifying its output voltage to charge associated capacitor means and applying the first amplifier output voltage to a second amplifier means for comparison with a sawtooth reference voltage, the output voltage from the second amplifier means providing control signals to the individual heating elements.

106. A method for regulating power input in an electric heating apparatus utilizing at least one resistive heating element comprising the steps of:

(a) selecting a power setting for the heating element from a plurality of power settings,

(b) converting the selected power setting to control signals, and

(c) utilizing the control signals to actuate a piezoceramic relay device connected in circuit relationship to enable connection of a power source to the heating element, the piezoceramic relay device including a movable polarized piezoceramic bender member and movable electrical contact means which coact with fixed electrical contact means disposed thereby, the piezoceramic bender member maintaining the movable electrical contact means spaced apart from the fixed electrical contact means while the heating element is in an unenergized condition, the movable electrical contact means being connected to an electrically conductive spring element, the bender member and the spring element being operatively connected by an insulating means for common movement, the piezoceramic relay device including clamping means being secured at portions adjacent to and mechanically supporting the bender member and the spring element in a cantilever manner for operating the coacting electrical contact means.

107. The method of claim 106 wherein the piezoceramic relay device is actuated with DC energizing potential.

108. The method of claim 107 wherein the DC energization potential applied to actuate the piezoceramic relay device has the same polarity as the polarity of the potential used to polarize the piezoceramic relay device.

109. The method of claim 108 wherein the control signals are derived with solid state circuit means.

110. The method of claim 106 wherein the control signals are made further responsive to temperature feedback control means.

111. The method of claim 110 wherein the temperature control signals are derived as an error signal which is the function of the difference between the sensed temperature and a predetermined temperature setting.

112. The method of claim 111 wherein the predetermined temperature setting is selected by an operator from a plurality of available temperature settings.

113. The method of claim 109 wherein the solid state circuit means controls the percentage of time the power is applied to the heating element in accordance with the power level setting selected by the operator.

114. The method of claim 109 wherein the solid state circuit means provides DC energization potential to the bender member with a pair of high voltage active devices.

115. The method of claim 114 wherein the control signals are provided to the high voltage active devices with analog circuit means.

116. The method of claim 115 wherein the analog circuit means comprises a dual comparator network providing control signals to operate the heating element.

117. The method of claim 116 wherein the dual comparator network comprises first amplifier means which compares an input DC control voltage with a feedback voltage obtained by modifying its output voltage to charge associated capacitor means and applying the first amplifier output voltage to a second amplifier means for comparison with a sawtooth reference voltage, the output voltage from the second amplifier means providing actuating signals to the heating element.

118. The method of claim 117 wherein the control signals operate a pair of heating elements with the control signals operating one heating element being derived with a first sawtooth reference voltage having an inverse relationship with respect to a second sawtooth reference voltage used to derive the control signals operating the other heating element in order to avoid simultaneous power application to the heating elements.

119. The method of claim 118 wherein the analog circuit means derives the sawtooth reference voltages with unijunction relaxation oscillator means connected in circuit relationship with a pair of series connected feedback amplifier means so that the output from the first amplifier means provides the first sawtooth reference voltage and which upon further being applied to the second amplifier means provides the second sawtooth reference voltage.

120. A method for regulating power input to an electric range having a surface cooking mechanism which employs at least one resistive heating element, power setting selector means enabling an operator to select the desired power level of operation for an individual heating element, temperature control means, and control means to regulate power input to an individual heating element comprising the steps of:

(a) selecting a power setting for an individual heating element from a plurality of power settings,

(b) converting the selected power setting to power control signals,

(c) utilizing the power control signals to actuate a piezoceramic relay device connected in circuit relationship to enable connection of a power source to the individual heating element, the piezoceramic relay device including a movable polarized piezoceramic bender member and movable electrical contact means which coact with fixed electrical contact means disposed thereby, the piezoceramic bender member maintaining the movable electrical contact means spaced apart from the fixed electrical contact means while the heating element is in an unenergized condition, the movable electrical contact means being connected to an electrically conductive spring element, the bender member and the spring element being operatively connected by an insulating means for common movement, the piezoceramic relay device including clamping means being secured at portions adjacent to and mechanically supporting the bender member and the spring element in a cantilever manner for operating the coacting electrical contact means, and thereby causing the piezoceramic bender member to deflect and complete a circuit between the power source and the individual heating element,

(d) sensing temperature achieved with the operating heating element to derive temperature control signals, and

(e) terminating power input to the individual heating element when the sensed temperature reaches a predetermined temperature by causing the coacting contact means of the piezoceramic relay device to open.

121. The method of claim 120 wherein the piezoceramic relay device is actuated with DC energizing potential.

122. The method of claim 121 wherein the DC energization potential applied to actuate the piezoceramic relay device has the same polarity as the polarity of the potential used to polarize the piezoceramic relay device.

123. The method of claim 120 wherein the control signals are derived with solid state circuit means.

124. The method of claim 120 wherein the predetermined temperature setting is selected by an operator from a plurality of available temperature settings.

125. The method of claim 120 wherein the control signals are made further responsive to temperature feedback control means.

126. The method of claim 123 wherein the solid state circuit means controls the percentage of time the power is applied to the heating element in accordance with the power level setting selected by an operator.

127. The method of claim 121 wherein the solid state circuit means provides DC energization potential to the bender member with a pair of high voltage active devices.

128. The method of claim 126 wherein the control signals are provided to the high voltage active devices with analog circuit means.

129. The method of claim 128 wherein the analog circuit means comprises a dual comparator network providing control signals to an individual heating element.

130. The method of claim 129 wherein the dual comparator network comprises first amplifier means which compares an input DC control voltage with a feedback voltage obtained by modifying its output voltage to charge associated capacitor means and applying the first amplifier output voltage to a second amplifier means for comparison with a sawtooth reference voltage, the output voltage from the second amplifier means providing actuating signals to the heating element.

131. The method of claim 130 wherein the control signals operate a pair of heating elements with the control signals operating one heating element being derived with a first sawtooth reference voltage having an inverse relationship with respect to a second sawtooth reference voltage used to derive the control signals operating the other heating element in order to avoid simultaneous power application to the heating elements.

132. The method of claim 131 wherein the analog circuit means derives the sawtooth reference voltages with unijunction relaxation oscillator means connected in circuit relationship with a pair of series connected feedback amplifier means so that the output from the first amplifier means provides the first sawtooth reference voltage and which upon further being applied to the second amplifier means provides the second sawtooth reference voltage.

133. The method of claim 120 wherein the surface cooking mechanism includes at least two resistive heating elements and each heating element is connected to an individual piezoceramic relay device.

134. The method of claim 120 which further includes the step of actuating additional switching means to interrupt power being supplied to an individual heating element when the power setting selector means are turned to an off condition.

135. A method for regulating power input to an electric range having an oven cooking mechanism which employs at least one resistive heating element, power setting selector means enabling an operator to select the desired power level of operation for an individual heating element, temperature control means, and control means to regulate power input to an individual heating element comprising the steps of:

(a) selecting a power setting for an individual heating element from a plurality of power settings,

(b) converting the selected power setting to power control signals,

(c) utilizing the power control signals to actuate a piezoceramic relay device connected in circuit relationship to enable connection of a power source to the individual heating element, the piezoceramic relay device including a movable polarized piezoceramic bender member and movable electrical contact means which coact with fixed electrical contact means disposed thereby, the piezoceramic bender member maintaining the movable electrical contact means spaced apart from the movable electrical contact means while the heating element is in an unenergized condition, the movable electrical contact means being connected to an electrically conductive spring element, the bender member and the spring element being operatively connected by an insulating means for common movement, the piezoceramic relay device including clamping means being secured at portions adjacent to and mechanically supporting the bender member and the spring element in a cantilever manner for operating the coacting electrical contact means, the power control signals causing the piezoceramic bender member to deflect and complete a circuit between the power source and the individual heating element,

(d) sensing temperature achieved with the operating heating element to derive temperature control signals, and

(e) terminating power input to the individual heating element when the sensed temperature reaches a predetermined temperature by causing the coacting contact means of the piezoceramic relay device to open.

136. The method of claim 135 wherein the piezoceramic relay device is actuated with DC energizing potential.

137. The method of claim 136 wherein the DC energizing potential applied to actuate the piezoceramic relay device has the same polarity as the polarity of the potential used to polarize the piezoceramic relay device.

138. The method of claim 135 wherein the control signals are derived with solid state circuit means.

139. The method of claim 136 wherein the predetermined temperature setting is selected by an operator from a plurality of available temperature settings.

140. The method of claim 136 wherein the control signals are made further responsive to feedback control means.

141. The method of claim 138 wherein the solid state circuit means controls the percentage of time the power is applied to the heating element in accordance with the power level setting selected by an operator.

142. The method of claim 138 wherein the solid state circuit means provides DC energization potential to the bender member with a pair of high voltage active devices.

143. The method of claim 142 wherein the control signals are provided to the high voltage active devices with analog circuit means.

144. The method of claim 143 wherein the analog circuit means comprises a dual comparator network providing control signals to an individual heating element.

145. The method of claim 144 wherein the dual comparator network comprises first amplifier means which compares an input DC control voltage with a feedback voltage obtained by modifying its output voltage to charge associated capacitor mean and applying the first amplifier output voltage to a second amplifier means for comparison with a sawtooth reference voltage, the output voltage from the second amplifier means providing actuating signals to the heating element.

146. The method of claim 145 wherein the control signals operate a pair of heating elements with the controls signals operating one heating element being derived with a first sawtooth reference voltage having an inverse relationship with respect to a second sawtooth reference voltage used to derive the control signals operating the other heating element in order to avoid simultaneous power application to the heating elements.

147. The method of claim 146 wherein the analog circuit means derives the sawtooth reference voltages with unijunction relaxation oscillator means connected in circuit relationship with a pair of series connected feedback amplifier means so that the output from the first amplifier means provides the first sawtooth reference voltage and which upon further being applied to the second amplifier means provides the second sawtooth reference voltage.

148. The method of claim 135 wherein the oven cooking mechanism includes at least two resistive heating elements and each heating element is connected to an individual piezoceramic relay device.

149. The method of claim 135 which further includes the step of actuating additional switching means to interrupt power being supplied to an individual heating element when the power setting selector means are turned to an off condition.

150. A method for regulating power input to a plurality of resistive heating elements in an electric range having at least one surface cooking mechanism and at least one oven mechanism, with each mechanism employing at least one resistive heating element, power setting selector means enabling an operator to select the desired power level of operation for an individual heating element in the respective mechanism, temperature control means, and control means to regulate power input to an individual heating element in the respective mechanism comprising the steps of:

(a) selecting a power setting for an individual heating element in the surface cooking mechanism from a plurality of power settings,

(b) converting the selected power setting for the individual heating element in the surface cooking mechanism to first power control signals,

(c) utilizing the first power control signals for the individual heating element in the surface cooking mechanism to actuate a first piezoceramic relay device connected in circuit relationship to enable connection of a power source to the surface cooking mechanism, the first piezoceramic relay device including a movable polarized piezoceramic bender member and movable electrical contact means which coact with fixed electrical contact means disposed thereby, the piezoceramic bender member maintaining the movable electrical contact means spaced apart from the fixed electrical contact means while the heating element is in an unenergized condition, the movable electrical contact means being connected to an electrically conductive spring element, the bender member and the spring element being operatively connected by an insulating means for common movement, the piezoceramic relay device including clamping means being secured at portions adjacent to and mechanically supporting the bender member and the spring element in a cantilever manner for operating the coacting electrical contact means, the control signals causing the piezoceramic bender member to deflect and complete a circuit between the power source and the individual heating element in the surface cooking mechanism,

(d) sensing temperature achieved with the operating heating element in the surface cooking mechanism to derive first temperature control signals,

(e) terminating power input to the individual heating element in the surface cooking mechanism when the sensed temperature reaches a predetermined temperature by causing the coacting contact means of the first piezoceramic relay device to open with the first temperature control signals,

(f) selecting a power setting for an individual heating element in the oven cooking mechanism from a plurality of power settings,

(g) converting the selected power setting for the individual heating element in the oven cooking mechanism to second power control signals,

(h) utilizing the second power control signals to actuate a second piezoceramic relay device connected in circuit relationship to enable connection of the power source to the individual heating element in the oven cooking mechanism, the second piezoceramic relay device including a movable polarized piezoceramic bender member and movable electrical contact means which coact with fixed electrical contact means disposed thereby, the piezoceramic bender member maintaining the movable electrical contact means spaced apart from the fixed electrical contact means while the heating element in the oven mechanism is in an unenergized condition, the movable electrical contact means being connected to an electrically conductive spring element, the bender member and the spring element being operatively connected by an insulating means for common movement, the piezoceramic relay device including clamping means being secured at portions adjacent to and mechanically supporting the bender member and the spring element in a cantilever manner for operating the coacting electrical contact means, the control signals causing the piezoceramic bender member to deflect and complete a circuit between the power source and the individual heating element in the oven cooking mechanism,

(i) sensing temperature achieved with the operating heating element in the oven cooking mechanism to derive second temperature control signals, and

(j) terminating power input to the individual heating element in the oven cooking mechanism when the sensed temperature reaches a predetermined temperature by causing the coacting contact means of the second piezoceramic relay device to open with the second temperature control signals.

151. The method of claim 150 wherein the piezoceramic relay devices are actuated with DC energizing potential.

152. The method of claim 151 wherein the DC energizing potential applied to actuate the piezoceramic relay devices have the same polarity as the polarity of the potential used to polarize the piezoceramic relay devices.

153. The method of claim 150 wherein the control signals are derived with solid state circuit means.

154. The method of claim 150 wherein the predetermined temperature settings are selected by an operator from a plurality of available temperature settings.

155. The method of claim 153 wherein the solid state circuit means controls the percentage of time the power is applied to the heating elements in accordance with the power level settings selected by an operator.

156. The method of claim 153 wherein the solid state circuit means provides DC energization potential to the bender members with a pair of high voltage active devices.

157. The method of claim 156 wherein the control signals are provided to the high voltage active devices with analog circuit means.

158. The method of claim 157 wherein the analog circuit means comprises a dual comparator network providing control signals to operate the heating elements.

159. The method of claim 158 wherein the dual comparator network comprises first amplifier means which compares an input DC control voltage with a feedback voltage obtained by modifying its output voltage to charge associated capacitor means and applying the first amplifier output voltage to a second amplifier means for comparison with a sawtooth reference voltage, the output voltage from the second amplifier means providing actuating signals to the heating elements.

160. The method of claim 159 wherein the control signals operate a pair of heating elements with the control signals operating one heating element being derived with a first sawtooth reference voltage having an inverse relationship with respect to a second sawtooth reference voltage used to derive the control signals operating the other heating element in order to avoid simultaneous power application to the heating elements.

161. The method of claim 160 wherein the analog circuit means derives the sawtooth reference voltages with unijunction relaxation oscillator means connected in circuit relationship with a pair of series connected feedback amplifier means so that the output from the first amplifier means provides the first sawtooth reference voltage and which upon further being applied to the second amplifier means provides the second sawtooth reference voltage.

162. The method of claim 150 wherein at least one of the cooking mechanisms include at least two resistive heating elements and each heating element is connected to an individual piezoceramic relay device.

163. The method of claim 150 which further includes the step of actuating additional switching means to interrupt power being supplied to an individual heating element when the power selector means are turned to an off condition.