Positive pressure amplified gas-air valve for a low NOx premix combustion system

Patent metadata

Field	Value
Publication number	US-10480783-B2
Application number	US-201715690509-A
Country	US
Kind code	B2
Filing date	Aug 30, 2017
Priority date	Aug 30, 2017
Publication date	Nov 19, 2019
Grant date	Nov 19, 2019

Abstract

Systems and methods are described related to a premix combustion system used in a furnace system. Prior systems have to create a negative pressure in the premix chamber to draw gas into the chamber. Embodiments under the current disclosure can use an amplifier that is pneumatically coupled to an air supply and a secondary location (besides the gas valve). Coupling to the amplifier to a location apart from the gas valve allows the system to avoid a negative pressure in the mixing chamber. The amplifier can apply an amplified pressure or signal to a gas valve regulator and thereby raise the gas pressure so that the gas supply is driven into the premix chamber.

First claim

What is claimed is:

1. A premix combustion system for a furnace in an HVAC system, comprising: a chamber operable to receive gas and air and deliver a gas-air mix to a combustion chamber, the chamber comprising an air inlet operable to receive an air supply; a gas valve, the gas valve comprising a gas line extending from the gas valve to the chamber at a location downstream from the air inlet, the gas valve further comprising a gas supply inlet operable to receive gas from a gas source; an amplifier comprising; an air interface pneumatically coupled to the air supply; a secondary interface proximate the air interface and pneumatically coupled to a secondary location in the HVAC system; and a regulator coupled to the amplifier and coupled to the gas valve; wherein the amplifier is configured to detect a pressure differential between the air supply and the secondary location, and to cause the regulator coupled to the gas valve to apply an amplified pressure to gas in the gas line.

2. The premix of claim 1 wherein the secondary location comprises an outlet.

3. The premix of claim 1 wherein the secondary location comprises an exhaust line.

4. The premix of claim 1 wherein the chamber comprises flow restrictors.

5. The premix of claim 1 wherein the regulator linkage applies a 4:1 amplification to the gas valve.

6. The premix of claim 3 wherein if the secondary location is exposed to atmospheric pressure then the regulator turns off the gas valve.

7. The premix of claim 1 wherein the secondary location is in the chamber downstream of the air inlet.

8. The premix of claim 1 wherein the regulator further comprises a membrane between the air interface and the secondary interface.

9. A furnace for use in an HVAC system, comprising: a premix combustion system, comprising; a chamber operable to receive gas and air and deliver a gas-air mix to a combustion chamber, the chamber comprising an air inlet operable to receive an air supply; a gas valve, the gas valve comprising a gas line extending from the gas valve to the chamber at a location downstream from the air inlet, the gas valve further comprising a gas supply inlet operable to receive gas from a gas source; an amplifier comprising; an air interface pneumatically coupled to the air supply; a secondary interface proximate the air interface and pneumatically coupled to a secondary location in the HVAC system; and a regulator coupled to the amplifier and to the gas valve, wherein the amplifier is configured to detect a pressure differential between the air supply and the secondary location, and to cause the regulator coupled to the gas valve to apply an amplified pressure to gas in the gas line; one or more heat exchangers operable to receive combusted gas-air mix from the combustion chamber; one or more inducers operable to induce the flow of combusted gas-air mix through the one or more heat exchangers; one or more blowers operable to direct air flow across the one or more heat exchangers; and an exhaust operable to direct combusted gas-air mix from the one or more heat exchangers to an exhaust vent.

10. The furnace of claim 9 wherein the secondary location comprises an outlet.

11. The furnace of claim 9 wherein the secondary location comprises an exhaust line.

12. The furnace of claim 9 wherein the chamber comprises flow restrictors.

13. The furnace of claim 9 wherein the amplifier coupled to the regulator applies a 4:1 amplification to the gas valve.

14. The furnace of claim 11 wherein if the secondary location is exposed to atmospheric pressure then the regulator turns off the gas valve.

15. The furnace of claim 9 wherein the secondary location is in the chamber downstream of the air inlet.

16. The furnace of claim 9 wherein the amplifier further comprises a membrane between the air interface and the secondary interface.

17. A method of operating a furnace in an HVAC system, comprising: providing a premix chamber configured to receive an air supply and a gas supply and to supply a gas-air mix to a combustion chamber; providing a gas valve comprising a gas supply inlet configured to receive the gas supply from a gas source and a gas line configured to deliver the gas supply to the premix chamber; receiving the air supply in the premix chamber at an air inlet; receiving the gas supply in the premix chamber from the gas line connected to the premix chamber downstream of the air inlet; providing an amplifier operable to detect a pressure differential between a first interface and a second interface, coupling the amplifier to the regulator and further operable to apply a pressure differential to the gas supply in the gas line; coupling the first interface pneumatically to the air supply; coupling the second interface pneumatically to a secondary location in the HVAC system; receiving the gas-air mix in the combustion chamber; igniting the gas-air mix in the combustion chamber; and providing the ignited gas-air mix to another component of the furnace.

18. The method of claim 17 wherein the secondary location comprises an exhaust line.

19. The method of claim 17 wherein the secondary location comprises a location in the premix chamber downstream from the gas inlet.

20. The method of claim 17 wherein the regulator linkage applies a 4:1 amplification to the gas valve.

21. The method of claim 17 wherein the regulator comprises a membrane between the first and second interface.

Assignees

• Lennox Ind Inc

Inventors

• Kowald Glenn W

Classifications

• F23N2235/20

  Membrane valves · CPC title

• F23N1/027

  using mechanical means · CPC title

• F24H3/087

  using fluid fuel · CPC title

• F24H9/1881 Primary

  using fluid fuel · CPC title

• F24H3/065

  using fluid fuel · CPC title