Safe Class-2 motor control circuit and method adapted for electric vacuum cleaning system suction motor and agitator motor control

• US 6,239,576 B1
• Filed: 09/03/1999
• Issued: 05/29/2001
• Est. Priority Date: 09/04/1998
• Status: Expired due to Fees

• Current Assignee: Stewart Breslin
• Original Assignee: Beamco, Inc.
• Inventors: McCarthy, James J., Breslin, John J.
• Primary Examiner(s): Nappi, Robert E.
• Assistant Examiner(s): Duda, Rina I.
• Application Number:
  US09/390,000
• Time in Patent Office: 634 Days
• Field of Search: 318/38, 318/787, 318/803, 318/806, 318/434, 15/335, 15/377, 15/25, 307/38, 307/116, 307/141
• US Class Current: 318/805
• CPC Class Codes: A47L 9/2831 Motor parameters, e.g. motor load or speed
• CPC Class Codes: A47L 9/2842 Suction motors or blowers
• CPC Class Codes: A47L 9/2847 Surface treating elements
• CPC Class Codes: A47L 9/2857 User input or output elements for control, e.g. buttons, switches or displays
• CPC Class Codes: A47L 9/2889 Safety or protection devices or systems, e.g. for prevention of motor over-heating or for protection of the user

Abstract

A control circuit for selectively energizing at least one electrical device coupled to the control circuit via a pair of conductive wires with an operating voltage. The control circuit comprises a control circuit for selectively supplying and withholding operating electrical power to at least one electrical device. A first current detector is connected to a control voltage and senses a current flow resulting from closure of a circuit connected to a control voltage in at least one wire of the pair of conductive wires. A second current detector is connected to the operating voltage and senses a current flow resulting from closure of a circuit connected to the operating voltage in at least one wire of the pair of conductive wires. A first switching device responds to the first current detector to disconnect the control voltage from at least one of the wires and to connect the operating voltage to the conductive pair. A second switching device responds to the second current detector to maintain operating voltage to the conductor pair. The second switching device responds to the second current detector to connect operating power to the electrical device.

Claims

1. A control circuit for selectively energizing at least one electrical device coupled to said control circuit via a pair of conductive wires with an operating voltage between 100 volts and 250 volts, said control circuit comprising:

a control circuit for selectively supplying and withholding operating electrical power to said at least one electrical device;

a first current detector connected to a control voltage less than said operating voltage and sensing a current flow resulting from closure of a circuit connected to said control voltage but not connected to said operating voltage in at least one wire of said pair of conductive wires;

a second current detector connected to said operating voltage and sensing a current flow resulting from closure of a circuit when connected to said operating voltage in at least one wire of said pair of conductive wires;

a first switching device responsive to said first current detector to disconnect said control voltage from at least one of said wires and to connect said operating voltage to said conductive pair of wires;

a second switching device responsive to said second current detector to maintain said operating voltage to said pair of conductive wires, said second switching device responsive to said second current detector to connect said operating power to said electrical device; and

a delay circuit delaying connecting said operating voltage to said electrical device for a predetermined time to allow a safe transition from said control voltage to said operating voltage over said common pair of conductors.

2. The control circuit in claim 1, wherein said control voltage is a class-2 voltage.

3. The control circuit in claim 1, wherein said operating voltage is a voltage sufficient to provide sufficient voltage and current for operating said electrical device, said electrical device being selected from the group of electrical devices consisting of an electric motor, a vacuum cleaner agitator motor, a vacuum cleaner brush motor, a central vacuum cleaning system suction motor, a portable vacuum cleaner motor, and combinations thereof.

4. The control circuit in claim 1, wherein said operating voltage is a voltage in the range between about 100 volts and about 250 volts.

5. The control circuit in claim 1, wherein each of said first and second current detectors comprise an optical photo-cell pair including a light emitting portion and a light detecting portion, said light emitting portion operating when a sufficient current passes through said light emitting portion, said light detecting portion disposed to collect and sense light emitted by said light emitting portion and causing generation of a signal for controlling another circuit device.

6. A control system for selectively energizing and supplying power to a central and a remote electrical load device interconnected by a single connector pair from a common control located at the remote device comprising:

a. low voltage circuit having a value of voltage not hazardous for personnel for sensing when said common control is connected and activated;

b. power means at the location of the central electrical device for providing power to the conductor pair interconnecting said central device with the remote electrical device, said power means providing electrical voltage to said conductor pair;

c. said common control comprising switching means interposed in one conductor of said pair for conducting the flow of electrical current to said remote device, said switching means comprising a switch having a first position for conducting electrical current to said remote electrical device and a second position for preventing the conducting of electrical current to said remote device;

d. first detecting means at the location of said control device connected to said low voltage and interposed in one conductor of said pair for detecting an electrical current flow through said conductor pair, said detecting means comprising a current sensing device interposed in one of said pair;

e. second detecting means at the location of said control device connected to said power means and interposed in one conductor of said pair for detecting an electrical current flow through said conductor pair, said detecting means comprising a current sensing device interposed in one of said pair;

f. first actuating means responsive to current flow detected by said first detecting means for disconnecting said low voltage from said conductor pair and connecting said power means to said conductor pair;

g. second actuating means responsive to current flow detected by said second detecting means for maintaining connecting said power means to said conductor pair; and

h. said second actuating means responsive to current flow detected by said second detecting means for further connecting said power means to said central electrical device.

7. A control system for selectively energizing and supplying power to a central and a remote electrical load device interconnected by a single connector pair from a common control located at the remote device comprising:

a. low voltage circuit having a value of voltage not hazardous for personnel for sensing when said common control is connected and activated;

b. power means at the location of the central electrical device for providing power to the conductor pair interconnecting said central device with the remote electrical device, said power means providing electrical voltage to said conductor pair;

c. said common control comprising switching means interposed in one conductor of said pair for conducting the flow of electrical current to said remote device, said switching means comprising a switch having a first position for conducting electrical current to said remote electrical device and a second position for preventing the conducting of electrical current to said remote device;

d. first detecting means at the location of said control device connected to said low voltage and interposed in one conductor of said pair for detecting an electrical current flow through said conductor pair, said detecting means comprising a current sensing device interposed in one of said pair;

e. second detecting means at the location of said control device connected to said power means and interposed in one conductor of said pair for detecting an electrical current flow through said conductor pair, said detecting means comprising a current sensing device interposed in one of said pair;

f. first actuating means responsive to current flow detected by said first detecting means for disconnecting said low voltage from said conductor pair and connecting said power means to said conductor pair;

g. second actuating means responsive to current flow detected by said second detecting means for maintaining connecting said power means to said conductor pair;

h. said second actuating means responsive to current flow detected by said second detecting means for further connecting said power means to said central electrical device; and

i. a delay circuit delaying said first actuating means disconnecting said low voltage from said remote electrical device and connecting said power means to said remote electrical device responsive to said first detecting means for a predetermined time.

8. A circuit for selectively energizing an electrical device, said circuit comprising:

first and second current detectors, each sensing current flow or a lack of current flow in a wire of a pair of conductive wires;

a first switching device responsive to said first current detector to disconnect a control voltage from at least one of said wires and to connect a operating voltage to said conductive pair;

a second switching device responsive to said second current detector to maintain said operating voltage to said conductor pair, said second switching device responsive to said second current detector to connect said operating power to said electrical device; and

at least one of said first and said second switching devices interposing a delay in said connecting and/or said disconnecting so that a voltage present across said common pair of conductors transitions between said control voltage and said operating voltage over a predetermined period of time.

9. The circuit in claim 8, wherein said control voltage is a Class-2 voltage and said operating power provides at least 100 volts.

10. In a circuit for selectively energizing an electrical device, a method comprising steps of:

closing a switch to initiate a first electrical current flow;

sensing said first current flow in at least one wire of a pair of conductive wires;

sensing a second current flow in at least one wire of said pair of conductive wires;

disconnecting a control voltage from at least one of said wires in a first switching device in response to said sensed first current and connecting an operating voltage to said conductive pair, said disconnecting and connecting occurring in a gradual manner with a delay so that both the control voltage and the operating voltage appear on a common pair ow conductive wires but at different times; and

maintaining said operating voltage to said conductor pair in response to said sensed second current.

11. A control circuit for selectively energizing at least one electrical device coupled to said control circuit via a single two-wire pair of electrical conductors with an operating voltage, said control circuit comprising:

a control circuit for selectively supplying and withholding operating electrical power to said at least one electrical device over said single two-wire pair of electrical conductors;

a first current detector connected to a control voltage and sensing a current flow resulting from closure of a circuit connected to a control voltage in at least one wire of said single two-wire pair of conductors;

a second current detector connected to said operating voltage and sensing a current flow resulting from closure of a circuit connected to said operating voltage in at least one wire of said single two-wire pair of conductors;

a first switching device responsive to said first current detector to disconnect said control voltage from at least one of said wires and to connect said operating voltage to said single two-wire pair of conductors;

a second switching device responsive to said second current detector to maintain said operating voltage to said single two-wire pair of conductors;

said second switching device responsive to said second current detector to connect said operating power to said electrical device; and

said control voltage and operating voltage being provided over said single two-wire pair of conductors, a time delay being provided for transition between the time said single pair of conductors carry said control voltage and carry said operating voltage.

12. The control circuit in claim 11, wherein said control voltage is a class-2 voltage and said operating voltage sufficient to provide sufficient voltage and current for operating said electrical device.

13. The control circuit in claim 12, wherein said operating voltage is a voltage in the range between about 100 volts and about 250 volts.

14. The control circuit in claim 13, wherein each of said first and second current detectors comprise an optical photo-cell pair including a light emitting portion and a light detecting portion, said light emitting portion operating when a sufficient current passes through said light emitting portion, said light detecting portion disposed to collect and sense light emitted by said light emitting portion and causing generation of a signal for controlling another circuit device.

15. A control system for selectively energizing and supplying power to a central and a remote electrical load device interconnected by a single conductor pair from a common control located at the remote device comprising:

low voltage circuit having a value of voltage not hazardous for personnel for sensing when said common control is connected and activated;

power means at the location of the central electrical device for providing power to the conductor pair interconnecting said central device with the remote electrical device, said power means providing electrical voltage to said conductor pair;

said common control comprising switching means interposed in one conductor of said pair for conducting the flow of electrical current to said remote device, said switching means comprising a switch having a first position for conducting electrical current to said remote electrical device and a second position for preventing the conducting of electrical current to said remote device;

first detecting means at the location of said control device connected to said low voltage and interposed in one conductor of said pair for detecting an electrical current flow through said conductor pair, said detecting means comprising a current sensing device interposed in one of said pair;

second detecting means at the location of said control device connected to said power means and interposed in one conductor of said pair for detecting an electrical current flow through said conductor pair, said detecting means comprising a current sensing device interposed in one of said pair;

first actuating means responsive to current flow detected by said first detecting means for disconnecting said low voltage from said conductor pair and connecting said power means to said conductor pair;

second actuating means responsive to current flow detected by said second detecting means for maintaining connecting said power means to said conductor pair; and

said second actuating means responsive to current flow detected by said second detecting means for further connecting said power means to said central electrical device; and

a circuit delaying said first actuating means disconnecting said low voltage from said remote electrical device and connecting said power means to said remote electrical device responsive to said first detecting means for a predetermined time.

16. The control system of claim 15, wherein said first and said second detecting means each comprises a current sensing device interposed in one of said conductor pair.

17. A control system operating at a Class-2 voltage for selectively energizing and supplying operating power to a central electric load device and to a remote electric load device interconnected by a single two-wire conductor pair which conducts a single current circuit only from a common control located at the remote device comprising:

an electrical power providing circuit at the location of the central electrical device for providing electrical power to said central device, electrical power to said remote device, and a Class-2 voltage and an electrical current for the single circuit of the conductor pair interconnecting said central device with the remote electrical device;

a first switch interposed between said electrical power providing circuit and said central device for controlling the flow of electrical current to said central device;

a second switch at the location of said remote device and interposed in one conductor of said pair for controlling the flow of electrical current to said remote device;

a current sensor at the location of said central device and interposed in one conductor of said pair, said current sensor generating a control voltage in response to a flow of current through said conductor pair;

an actuator responsive to said current sensor and coupled to said first switch for actuating said first switch in response to the control voltage generated by said current sensor; and

a circuit delaying said first actuating means disconnecting said low voltage from said remote electrical device and connecting said power means to said remote electrical device responsive to said first detecting means for a predetermined time.

18. A control system as in claim 17, wherein said common control comprises a switch.

19. A control system as in claim 17, wherein said actuating means comprises a triac.

20. A control system as in claim 17, wherein said central device comprises an electrical motor.

21. A control system as in claim 17, wherein said current sensor comprises a current sensing transformer.

22. A control system as in claim 17, wherein said current sensor comprises a relay coil.

23. A control system as in claim 17, wherein said current sensor comprises a four-diode bridge circuit and photocell including a photoemitter and a photodetector.

24. A control system as in claim 17, wherein said remote device comprises an agitator motor.

25. A residential electrical system comprising:

means for receiving a potentially hazardous electrical utility line voltage and current;

a control circuit for applying a safe class-2 voltage to a single two-conductor pair of wires under first predetermined conditions and said potentially hazardous electrical utility line voltage to the same electrical two-conductor pair of wires under second predetermined conditions; and

a transition between said class-2 voltage and said potentially hazardous electrical utility voltage being initiated by a change in open/closed state of a switch.