Electrical control system for relay operation responsive to thermostat input having improved efficiency

• US 5,655,709 A
• Filed: 05/29/1996
• Issued: 08/12/1997
• Est. Priority Date: 05/29/1996
• Status: Expired due to Fees

• Current Assignee: Sensata Technologies Incorporated (Sensata Technologies Holding Plc)
• Original Assignee: Texas Instruments, Inc.
• Inventors: Garnett, Ronald E., Bailey, Walter H.
• Primary Examiner(s): Tanner, Harry B.
• Application Number:
  US08/654,803
• Time in Patent Office: 440 Days
• Field of Search: 236/68 R, 236/68 B, 236/68 C, 236/1 E, 237/2 A, 237/2 R, 219/511, 337/324, 337/377
• US Class Current: 236/68.00B
• CPC Class Codes: G05D 23/30 Automatic controllers with an auxiliary heating device affecting the sensing element, e.g. for anticipating change of temperature

Abstract

A temperature control system is shown in which a thermostat circuit is combined with a power supply to produce a higher anticipator current for a W1 signal while reducing power consumption and heat generation of the circuit. A first relay power signal is provided by an unbalanced bridge rectifier (D1, D2, D3, D4, D7, D8) while current drawn through the anticipator resistor (AR1) by means of an additional bridge rectifier circuit (D7, D8, D9, D10) is merged with the first relay power signal. In a second embodiment, an unbalanced bridge rectifier (D1, D4, D7, D2, D3, D8) has an output connected to a first stage relay power signal line as well as to second and third relay power signal lines. A second stage of the power supply includes a first additional bridge rectifier (D5, D6, D7, D8) connected to the second relay power signal line that drives current through the W1 anticipator while in a third stage of the power supply a second additional rectifier (D20, D21, D7, D8) is connected to the third relay power signal line and draws current through the W2 anticipator. Each stage of power adds more capacitance (C12, C11, C10) as the power requirements increase.

Claims

1. A temperature control having a plurality of electric relays each having a coil with electrical contacts controlled by energization of the respective relay coil, a microprocessor for controlling energization of the plurality of electric relays, a power supply comprising a low voltage source connected between an R line and earth ground C, a thermostat having first and second switches and respective serially connected first and second anticipator resistors respectively forming W1 and W2 signal lines, the R line also connected to each of the switches, the W1 and W2 signal lines connected to inputs of the microprocessor through current limiting resistors, a first bridge rectifier having an input and an output, the input connected to the R line and the output connected to a relay power signal line to each of the relay coils under the control of output signals from the microprocessor for energizing the relay coils, a first additional bridge rectifier having an input and output, the input of the first additional bridge rectifier connected to the W1 signal line and the output of the first additional bridge circuit connected to the relay power signal line to at least one of the relay coils whereby current will be drawn through the first anticipator resistor to form part of the relay drive power of said at least one of the relay coils.

2. A temperature control system according to claim 1 further comprising a second additional bridge rectifier having an input and an output, the input of the second additional bridge rectifier connected to the W2 signal line and the output of the second additional bridge rectifier connected to at least one other of the relay coils.

3. A temperature control system according to claim 1 in which the first bridge rectifier is unbalanced and the first additional bridge rectifier is balanced.

4. A temperature control system according to claim 2 in which the first bridge rectifier is unbalanced and the first and second additional bridge rectifiers are balanced.

5. A temperature control system according to claim 3 in which the first bridge rectifier has four legs with two serially connected diodes in each of two legs and a single diode in each of two legs.

6. A temperature control system according to claim 4 in which the first bridge rectifier has four legs with two serially connected diodes in each of two legs and a single diode in each of two legs.

7. A temperature control system according to claim 1 further comprising a capacitor connected across each of the first bridge rectifier and the first additional bridge rectifier to increase the RMS voltage of the output of the respective bridge rectifiers.

8. A temperature control system according to claim 2 further comprising a capacitor connected across each of the first, first additional, and second additional bridge rectifiers to increase the RMS voltage of the outputs of the respective bridge rectifiers.

9. A temperature control system having a plurality of electric relays each having a coil with electrical contacts controlled by energization of the respective relay coil, a microprocessor for controlling energization of the plurality of electric relays, a power supply comprising a low voltage source connected between an R line and earth ground C, a thermostat having first and second switches serially connected to first and second anticipator resistors respectively forming W1 and W2 lines, the power source line R connected to the switches, the W1 and W2 lines connected to inputs of the microprocessor through current limiting resistors, a first bridge rectifier having an input and an output, the low voltage AC source coupled to the input of the first bridge rectifier with the output of the bridge rectifier connected to the relay coils under the control of output signals of the microprocessor and an additional bridge rectifier, the W1 line being connected through the additional bridge rectifier to the relay coils whereby anticipator current from the first anticipator resistor is drawn through the relay coils in proportion to the number of relay coils energized.

10. A temperature control system according to claim 9 in which the first bridge rectifier is unbalanced and the first additional bridge rectifier is balanced.

11. A temperature control system according to claim 10 in which the first bridge rectifier has four legs and two serially connected diodes in each of two legs and a single diode in each of two legs.

12. A temperature control system having a plurality of electric relays each having a coil with electrical contacts controlled by energization of the respective relay coil, a microprocessor for controlling energization of the plurality of electric relays, a power supply comprising a low voltage AC source connected between an R line and earth ground C, a thermostat having first and second switches and respective serially connected first and second anticipator resistors respectively forming W1 and W2 signal lines, the R line also connected to each of the switches, the W1 and W2 signal lines connected to inputs of the microprocessor through current limiting resistors, a first bridge rectifier having an input and an output, the input connected to the R line and the output connected to first, second, and third relay power signal lines for the relay coils under the control of output signals from the microprocessor for energizing selected relay coils, a first additional bridge rectifier having an input and an output, the input of the first additional bridge rectifier connected to the W1 signal line and the output of the first additional bridge circuit connected to the second relay power signal line of the relay coils whereby current will be drawn through the first anticipator resistor to form part of the second relay power signal.

13. A temperature control system according to claim 12 comprising a second additional bridge rectifier having an input and an output, the input of the second additional bridge rectifier connected to the W2 signal line and the output of the second additional bridge rectifier connected to the third relay power signal line of the relay coils whereby current will be drawn through the second anticipator resistor to form part of the third relay power signal.

14. A temperature control system according to claim 12 in which the first bridge rectifier is unbalanced and the first additional bridge rectifier is balanced.

15. A temperature control system according to claim 12 in which the first bridge rectifier is unbalanced and the first and second additional bridge rectifiers are balanced.

16. A temperature control system according to claim 14 in which the first bridge rectifier has four legs with two serially connected diodes in each of two legs and a single diode in each of two legs.

17. A temperature control system according to claim 15 in which the first bridge rectifier has four legs with two serially connected diodes in each of two legs and a single diode in each of two legs.

18. A temperature control system according to claim 12 further comprising a capacitor connected across each of the first bridge rectifier and the first additional bridge rectifier to increase the RMS voltage of the output of the respective bridge rectifiers.

19. A temperature control system according to claim 12 further comprising a capacitor connected across each of the first, first additional, and second additional bridge claim rectifiers to increase the RMS voltage of the outputs of the respective bridge rectifiers.