Multi-purpose compressor controller

• US 4,510,547 A
• Filed: 11/12/1982
• Issued: 04/09/1985
• Est. Priority Date: 11/12/1982
• Status: Expired due to Fees

• Current Assignee: Johnson Service Company
• Original Assignee: Johnson Service Company
• Inventors: Rudich, George Jr.
• Primary Examiner(s): Salce, Patrick R.
• Application Number:
  US06/440,863
• Time in Patent Office: 879 Days
• Field of Search: 361/22, 361/24, 361/25, 361/27, 361/106, 361/92
• US Class Current: 361/22
• CPC Class Codes: H02H 7/08 for dynamo-electric motors

Abstract

The compressor motor controller of the present invention includes a hot motor detector adapted to be coupled to a plurality of temperature sensors for detecting an overtemperature condition of the compressor motor. The hot motor detector incorporates logic switching means for generating a motor control signal. A self diagnostic sensor is coupled to the hot motor detector for detecting an electrically shorted condition of the temperature sensors while a low voltage detector is coupled to the hot motor detector for sensing a low line voltage condition. Means are provided for protecting the compressor motor against the undesirable effects of short cycle operation while a lubricating oil pressure detector receives signals from a pressure transducer which are representative of oil pressure. A self-contained power supply provides a source of electrical power to the controller while an isolated output means is coupled to the separately mounted motor starting contactor for controllably energizing the compressor motor.

Claims

1. A controller for refrigeration and air conditioning compressor applications comprising:

hot motor detector means adapted to be coupled to a plurality of temperature sensors for detecting an over-temperature condition of a compressor motor, said hot motor detector means including the first logic switching means for generating a motor control signal;

sensor detector means coupled to said hot motor detector means and including a comparator and diodes connected to be conductive from sensor to comparator, said sensor detector means detecting only the simultaneous electrically shorted condition of all of said temperature sensors;

low voltage detector means coupled to said hot motor detector means for detecting a low line voltage condition;

short cycle protective means coupled to said first logic switching means for preventing short cycle operation of said controller;

pressure detector means coupled to said hot motor detector means for sensing a signal representative of lubrication oil pressure of said compressor, said pressure detector means being adapted for connection to a pressure transducer having a protective resistor internal thereto;

said pressure detector means further including means for providing a first starting time delay before enablement of said detector means and a second time delay for preventing disablement of said controller in the event of temporary diminishment of said oil pressure, said second time delay being significantly less than said first time delay;

power supply means coupled to said low voltage detector means for providing a source of electrical power to said compressor controller, and;

p1 isolated output means coupled to said pressure detector means for controllably energizing said compressor motor.

2. The invention set forth in claim 1 wherein said hot motor detector means includes a bridge section coupled to said temperature sensors for generating voltage signals related to sensor temperature.

3. The invention set forth in claim 2 wherein said hot motor detector means further includes an output receiver for sensing said voltage signals generated by said bridge section and providing a predetermined controller response time upon reception of said voltage signals.

4. The invention set forth in claim 3 wherein said controller further includes means for detecting a shorted temperature sensor, said shorted sensors detector including a comparator for de-energizing a compressor motor whenever any one of said sensors exhibits a resistance greater than a predetermined value.

5. The invention set forth in claim 3 wherein said controller further includes means for detecting a shorted temperature sensor, said shorted sensors detector including a comparator for de-energizing a compressor motor whenever the line voltage falls to an unacceptably low value.

6. A multipurpose controller for monitoring a plurality of operating conditions and controlling a compressor motor in refrigeration and air conditioning applications, said controller comprising:

hot motor detector means adapted to be coupled to a plurality of temperature sensors, said hot motor detector means including a bridge section for generating temperature-related voltage signals and an output receiver for sensing said voltage signals;

power supply means for providing a source of rectified electrical power to said controller;

low voltage detector means coupled intermediate said power supply means and said hot motor detector means for sensing a low line voltage condition, said low voltage detector means including means for comparing a first bias voltage having a relationship to line voltage and a second bias voltage having a predetermined relationship to a reference voltage;

a shorted sensors detector coupled to said hot motor detector means and including a comparator and diodes connected to be conductive from sensor to comparator, said sensor detector means detecting only the simultaneous electrically shorted condition of all of said temperature sensors;

a short cycle protective section for preventing energization of said compressor motor unless said motor has been de-energized for a predetermined minimum time;

a lubrication oil pressure detector for disabling said compressor motor upon decrease of lubrication oil pressure to a predetermined pressure, said pressure detector being adapted for connection to a pressure transducer having a protective resistor internal thereto;

said pressure detector further including means for providing a first starting time delay before enablement of said detector and a second time delay for preventing disablement of said controller in the event of temporary diminishment of said oil pressure, said second time delay being significantly less than said first time delay;

isolated output means coupled to said pressure detector means for controllably energizing said compressor motor, said isolated output means including an isolating coupler for isolating power switching means from said pressure detector means.

7. The invention set forth in claim 6 wherein said shorted sensors detector includes means for comparing voltage signals from said hot motor detector and voltage signals from said low voltage detector whereby said motor starting contactor may be de-energized when any of said voltage signals exceeds a predetermined value.

8. The invention set forth in claim 7 wherein said lube oil pressure detector includes means for providing manual reset of said controller over a predetermined range of time periods.