NEGATIVE PRESSURE CONDITIONING DEVICE WITH LOW PRESSURE CUT-OFF

• US 20070117056A1
• Filed: 11/30/2006
• Published: 05/24/2007
• Est. Priority Date: 11/09/2005
• Status: Active Grant

• Current Assignee: Ademco Inc. (Resideo Technologies, Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: Schultz, Michael
• Granted Patent: US 7,748,375 B2
• Time in Patent Office: Days
• US Class Current: 431/19
• CPC Class Codes: F23N 1/007 using mechanical means F23N1/04 - F23N1/10 take precedence
• CPC Class Codes: F23N 2225/04 pressure
• CPC Class Codes: F23N 2233/10 forcing air through heat exchangers
• CPC Class Codes: F23N 5/00 Systems for controlling combustion regulating fuel supply F23N1/00, regulating air supply or draught F23N3/00

Abstract

A pneumatic signal conditioning device may have a first fluid path and a second fluid path. The first fluid path includes a first inlet and a first outlet, and is configured such that the first outlet provides a first conditioned signal representing a pressure at the first inlet. Similarly, the second fluid path is configured such that the second outlet provides a second conditioned signal representing a pressure at the second inlet. A pressure switch may be disposed in fluid communication with the first fluid path and the second fluid path such that the first fluid path and the second fluid path pass through the pressure switch.

Claims

1. A pneumatic signal conditioning device comprising:

a first fluid path comprising a first inlet and a first outlet, the first fluid path configured such that the first outlet provides a first conditioned signal representing a pressure at the first inlet;

a second fluid path comprising a second inlet and a second outlet, the second fluid path configured such that the second outlet provides a second conditioned signal representing a pressure at the second inlet; and

a pressure switch disposed in fluid communication with the first fluid path and the second fluid path such that the first fluid path extends through a first side of the pressure switch and the second fluid path extends through a second side of the pressure switch.

2. The pneumatic signal conditioning device of claim 1, wherein the pressure switch outputs a pneumatic signal proportional to a difference between the first conditioned signal and the second conditioned signal.

3. The pneumatic signal conditioning device of claim 1, wherein the pressure switch provides a corresponding electrical signal when a difference between the first conditioned signal and the second conditioned signal is below a predetermined level.

4. The pneumatic signal conditioning device of claim 1, wherein the pressure switch is electrically coupled between a power source and an electrical input of a gas valve, and wherein the pressure switch opens when a difference between the first conditioned signal and the second conditioned signal is below a predetermined level, thereby cutting power to the gas valve.

5. The pneumatic signal conditioning device of claim 1, wherein the pressure switch comprises a pressure switch housing, the pressure switch housing defining an air volume that further conditions one of the first conditioned signal or the second conditioned signal.

6. The pneumatic signal conditioning device of claim 1, wherein at least one of the first inlet and the first outlet comprise a conditioning orifice.

7. The pneumatic signal conditioning device of claim 1, wherein at least one of the second inlet and the second outlet comprise a conditioning orifice.

8. The pneumatic signal conditioning device of claim 1, further comprising a third fluid path disposed between the first fluid path and the second fluid path upstream of the pressure switch to provide fluid communication between the first fluid path and the second fluid path.

9. A gas valve assembly comprising:

a gas valve configured to provide gas to a fuel burning appliance, the gas valve comprising a first port and a second port;

a signal conditioning device comprising a first fluid path including a first inlet and a first outlet and a second fluid path including a second inlet and a second outlet; and

a pressure switch having a first pressure switch inlet, a first pressure switch outlet, a second pressure switch inlet and a second pressure switch outlet;

wherein the first outlet is in fluid communication with the first pressure switch inlet, the second outlet is in fluid communication with the second pressure switch inlet, the first pressure switch outlet is in fluid communication with the first port of the gas valve and the second pressure switch outlet is in fluid communication with the second port of the gas valve.

10. The gas valve assembly of claim 10, wherein the first fluid path is configured such that the first outlet provides a first conditioned signal representing a pressure at the first inlet.

11. The gas valve assembly of claim 10, wherein the second fluid path is configured such that the second outlet provides a second conditioned signal representing a pressure at the second inlet.

12. The gas valve assembly of claim 10, wherein the first pressure switch outlet provides a pneumatic signal proportional to a pressure at the first outlet.

13. The gas valve assembly of claim 12, wherein the second pressure switch outlet provides a pneumatic signal proportional to a pressure at the second outlet.

14. The gas valve assembly of claim 12, wherein the pressure switch provides a signal to the gas valve, thereby stopping gas flow, if a difference between the pressure at the first outlet and the pressure at the second outlet indicates that it may not be safe to operate the fuel burning appliance.

15. The gas valve assembly of claim 12, wherein the pressure switch stops electrical power to the gas valve if a difference between the pressure at the first outlet and the pressure at the second outlet indicates that it may not be safe to operate the fuel burning appliance.

16. A forced-air furnace comprising:

a heat exchanger having an upstream port and a downstream port;

a burner configured to bum fuel and provide combustion products to the heat exchanger;

a gas valve configured to provide fuel to the burner, the gas valve comprising a first pressure port and a second pressure port; and

a pneumatic signal conditioning device comprising;

a first fluid path comprising a first inlet and a first outlet, the first fluid path configured such that the first outlet provides a first conditioned signal representing a pressure at the first inlet;

a second fluid path comprising a second inlet and a second outlet, the second fluid path configured such that the second outlet provides a second conditioned signal representing a pressure at the second inlet; and

a pressure switch disposed in fluid communication with the first fluid path and the second fluid path such that the first fluid path extends through a first side of the pressure switch and the second fluid path extends through a second side of the pressure switch;

wherein the first inlet is in fluid communication with the upstream port, the second inlet is in fluid communication with the downstream port, the first outlet is in fluid communication with the first pressure port and the second outlet is in fluid communication with the second pressure port.

17. The forced-air furnace of claim 16, wherein the upstream port is proximate the burner.

18. The forced-air furnace of claim 16, further comprising a collector box positioned proximate the downstream port.

19. The forced-air furnace of claim 16, further comprising a circulating blower adapted to blow air across an exterior of the heat exchanger.

20. The forced-air furnace of claim 16, further comprising a combustion gas blower adapted to pull combustion gases through an interior of the heat exchanger.

21. The forced-air furnace of claim 16, wherein the pneumatic signal conditioning device is adapted to dampen transient spikes.

22. The forced-air furnace of claim 16, wherein the pneumatic signal conditioning device is adapted to stop gas flow through the gas valve if a pressure drop across the heat exchanger is less than about 0.3 inches water (0.07 kPa).