Interface for interconnecting a thermostat and an electronically commutated motor

• US 5,220,255 A
• Filed: 10/12/1990
• Issued: 06/15/1993
• Est. Priority Date: 10/12/1990
• Status: Expired due to Fees

• Current Assignee: Lennox Manufacturing Inc. (Lennox International Incorporated)
• Original Assignee: Lennox Industries Incorporated (Lennox International Incorporated)
• Inventors: Alford, Malcolm L.
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): MARTIN, DAVID S
• Application Number:
  US07/596,227
• Time in Patent Office: 977 Days
• Field of Search: 318/138-139, 318/439, 318/254, 318/430, 236/DIG. 9, 236/67, 236/74 A, 236/91 R, 236/91 D
• US Class Current: 318/400.08
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/52 Indication arrangements, e.g. displays
• CPC Class Codes: F24F 11/76 by means responsive to temperature, e.g. bimetal springs
• CPC Class Codes: F24F 11/84 using valves
• CPC Class Codes: F24F 11/86 by controlling compressors within refrigeration or heat pump circuits
• CPC Class Codes: F24F 11/88 Electrical aspects, e.g. circuits
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: G05D 23/1913 delivering a series of pulses
• CPC Class Codes: Y10S 236/09 Fan control

Abstract

An interface is disclosed for operatively interconnecting a conventional thermostat and an electronically commutated motor ("ECM"). The interface provides enable, heating and rate signals to the ECM in response to the conventional fan, heat, valve and airflow signals from the thermostat.

Claims

1. An interface for operably interconnecting a thermostat of an air processing apparatus and an electronically commutated motor forming a part of an air moving system, said air processing apparatus including a heat pump/air conditioner controlled by a valve signal, said thermostat providing said valve signal, a fan signal, a heat signal and an airflow signal, said electronically commutated motor having an on/off input, a heating input, and a high/low input, comprising, in combination:

first means for providing an ENABLE signal at said on/off input in response to said fan signal or in response to said heat signal, said ENABLE signal enabling said electronically commutated motor;

second means for providing a HEATING signal at said heating input in response to said heat signal and in response to said valve signal whenever said valve signal indicates said heat pump/air conditioner is in a heating mode, said electronically commutated motor operating at a predetermined heat speed in response to said HEATING signal; and

third means for providing a RATE signal at said high/low input in response to said airflow signal from said thermostat, said electronically commutated motor being operable at one of at least two predetermined airflow rates in response to said RATE signal.

2. An interface as claimed in claim 1 wherein said first means includes first protection means for substantially avoiding feedback of said fan signal and said heat signal through said interface to said thermostat.

3. An interface as claimed in claim 2 wherein said second means includes second protection means for substantially avoiding feedback of said heat signal and said valve signal through said interface to said thermostat.

4. An interface as claimed in claim 3 wherein said first means further includes a Zener diode coupled to said on/off input.

5. An interface as claimed in claim 3 wherein said third means includes back-to-back Zener diodes.

6. An interface as claimed in claim 1 wherein said airflow signal is a pulse width modulated signal, and said RATE signal is a derivative thereof.