Thermostat for a gas engine heat pump and method for providing for engine idle prior to full speed or shutdown

• US 5,309,730 A
• Filed: 05/28/1993
• Issued: 05/10/1994
• Est. Priority Date: 05/28/1993
• Status: Expired due to Fees

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Strand, Rolf L., Uhrich, Daniel T.
• Primary Examiner(s): Tapolcai, William E.
• Application Number:
  US08/068,866
• Time in Patent Office: 347 Days
• Field of Search: 62/228.4, 62/323.1, 62/158, 62/323.4, 123/339
• US Class Current: 62/228.4
• CPC Class Codes: F02D 29/04 peculiar to engines driving pumps

Abstract

A thermostat which provides a pulse width modulated signal to a gas engine heat pump controller. The thermostat varies the width of the pulse width modulated signal to indicate the load required to heat or cool the room. The thermostat provides an initial idle time for the gas engine heat pump. The thermostat further steps the gas engine heat pump down from high speed operation and idles the engine prior to shutting the engine off.

Claims

1. A method of controlling a gas engine heat pump comprising the steps of:

A. determining current status of said gas engine heat pump;

B. determining whether a request for heating or cooling is present;

C. when a request for heating or cooling is present and the current status of said gas engine heat pump is off, idling said gas engine heat pump for a predetermined period of time;

D. stepping said gas engine heat pump up to a load level provided by load-sensing means; and

E. returning to step A.

2. The method of controlling a gas engine heat pump of claim 1, further comprising the steps of:

F. when a request for heating or cooling is not present and the current status of said gas engine heat pump is on, stepping said gas engine heat pump down to an idle speed;

G. idling said gas engine heat pump for a predetermined time;

H. shutting said gas engine heat pump off; and

I. returning to step A.

3. The method of controlling a gas engine heat pump of claim 1, further comprising the steps of:

J. when a request for heating or cooling is not present, returning to step A.

4. The method of controlling a gas engine heat pump of claim 2, further comprising the steps of:

K. when a request for heating or cooling is not present and the status of said gas engine heat pump is off, returning to step A; and

L. when a request for heating or cooling is present and the status of said gas engine heat pump is on, returning to step A.

5. A method of controlling a gas engine heat pump comprising the steps of:

A. determining current status of said gas engine heat pump;

B. determining whether a request for heating or cooling is present;

C. when a request for heating or cooling is not present and the current status of said gas engine heat pump is on, stepping said gas engine heat pump down to an idle speed;

D. idling said gas engine heat pump for a predetermined time;

E. shutting said gas engine heat pump off; and

F. returning to step A.

6. The method of controlling a gas engine heat pump of claim 5, further comprising the step of:

G. when a request for heating or cooling is present, returning to step A; and

H. when a request for heating or cooling is not present and the status of said gas engine heat pump is off, returning to step A.

7. A thermostat for a gas engine heat pump, said thermostat providing a load signal to a gas engine heat pump controller, the gas engine heat pump controller increasing or decreasing the gas engine heat pump'"'"'s operating level relative to said load signal, said thermostat comprising:

temperature sensing means for sensing ambient temperature;

means for selecting a desired room temperature;

means for calculating a differential between said desired temperature and said ambient temperature;

said load signal being proportional to said differential, said thermostat holding said load signal at an idle speed upon said differential becoming greater than zero for a predetermined time.

8. A thermostat for a gas engine heat pump, and a method for controlling the gas engine heat pump, said thermostat providing a load signal to a gas engine heat pump controller, the gas engine heat pump controller increasing or decreasing the gas engine heat pump'"'"'s operating level relative to said load signal, the method comprising the steps of:

A. determining current status of said gas engine heat pump;

B. determining whether a request for heating or cooling is present;

C. when a request for heating or cooling is present and the current status of said gas engine heat pump is off, idling said gas engine heat pump for a predetermined period of time;

D. stepping said gas engine heat pump up to a load level provided by load-sensing means; and

E. returning to step A.

9. The method of controlling a gas engine heat pump of claim 8, further comprising the steps of:

F. when a request for heating or cooling is not present and the current status of said gas engine heat pump is on, stepping said gas engine heat pump down to an idle speed;

G. idling said gas engine heat pump for a predetermined time;

H. shutting said gas engine heat pump off; and

I. returning to step A.

10. The method of controlling a gas engine heat pump of claim 8, further comprising the steps of:

J. when a request for heating or cooling is not present, returning to step A.

11. The method of controlling a gas engine heat pump of claim 9, further comprising the steps of:

K. when a request for heating or cooling is not present and the status of said gas engine heat pump is off, returning to step A; and

L. when a request for heating or cooling is present and the status of said gas engine heat pump is on, returning to step A.

12. A thermostat for a gas engine heat pump, and a method for controlling the gas engine heat pump, said thermostat providing a load signal to a gas engine heat pump controller, the gas engine heat pump controller increasing or decreasing the gas engine heat pump'"'"'s operating level relative to said load signal, the method comprising the steps of:

A. determining current status of said gas engine heat pump;

B. determining whether a request heating or cooling is present;

C. when a request for heating or cooling is not present and the current status of said gas engine heat pump is on, stepping said gas engine heat pump down to an idle speed;

D. idling said gas engine heat pump for a predetermined time;

E. shutting said gas engine heat pump off; and

F. returning to step A.

13. The method of controlling a gas engine heat pump of claim 12, further comprising the step of:

G. when a request for heating or cooling is present, returning to step A; and

H. when a request for heating or cooling is not present and the status of said gas engine heat pump is off, returning to step A.