Gas valve

Abstract

 The invention relates to a gas valve comprising a first safety valve, a second safety valve and a regulation system connected between said first safety valve and said second safety valve.
According to the invention said regulation system is operated by a servo control system.

Description

[0001] The invention is a servo regulated gas valve, where the regulation valve is a flow to open, which leads to an increased operational range of the gas valve.

[0002] Preferred improvements of the invention are disclosed in the dependent claims and the description. A preferred embodiment will be described in connection with the drawing, whereby:

Fig. 1

shows a gas valve according to the invention, and

Fig. 2

shows a detail of the gas valve according to Fig. 1.

[0003] Fig. 1 shows a gas valve 10 according to the invention. The gas valve 10 according to Fig. 1 comprises two safety valves 11, 12 - namely a first safety shut-off valve 11 and a second safety shut-off valve 12. Both safety valves 11, 12 are positioned within a common housing 13 and both safety valves 11, 12 are operated by separate solenoid drives, whereby Fig. 1 shows only the solenoid drive 14 of the first safety valve 11.

[0004] The gas valve 10 according to Fig. 1 comprises a gas inlet chamber 15 and a gas outlet chamber 16. Between said gas inlet chamber 15 and said gas outlet chamber 16 there is an internal gas chamber 17. In a closing status of the gas valve 10 a closing member 18 of the first safety valve 11 rests on a corresponding valve seat 19. For this, in the closing status of the gas valve 10 the first safety valve 11 separates said gas inlet chamber 15 from said internal gas chamber 17. In addition, in the closing status of the gas valve 10 a closing member 20 of the second safety valve 12 rests on a corresponding valve seat 21. This provides a separation of said internal gas chamber 17 from said gas outlet chamber 16 in the closing status of the gas valve 10.

[0005] A regulation system 22 consists of a regulation valve seat 24 and a regulation valve 27.

[0006] According to the invention the regulation system 22 is positioned between the two safety shut-off valves 11, 12. The regulation valve 27 is operated by a servo regulator valve - a so-called servo control system 23.

[0007] Said regulation system 22 is designed as a flow to open valve. The valve seat 24 of said regulation system 22 is profiled, what means that if the regulation valve 27 starts to move downwards, there is an opening, so that gas can flow from an internal compartment or gas chamber 25 into said internal gas chamber 17.

[0008] A channel 26 is provided in the regulation valve 27 of said regulation system 22. This provides a passageway for the gas from said internal compartment 25 to another internal compartment or gas chamber 28. This internal gas chamber 28 is positioned under a plate supported diaphragm 29, whereby a restriction or a so-called inlet orifice 30 provides for a gas passageway from said compartment 28 into a compartment or gas chamber 31 positioned above said plate supported diaphragm 29. The compartment 31 is a so-called servo pressure compartment (see Fig. 2).

[0009] According to Fig.1, the servo pressure compartment 31 is connected to a compartment or gas chamber 32 of said servo control system 23. A channel 33 provides for said connection between the compartments or gas chambers 31 and 32.

[0010] Said servo control system 23 is designed as a positive servo control system. The servo control system 23 can be an on/off, high/low, electrical modulation or gas/air ratio control system.

[0011] The operation of the gas valve 10 is the following:

[0012] The gas valve 10 according to Fig. 1, 2 is shown in a regulation status, regulating for minimum capacity.

[0013] When the gas valve 10 is not in operation, the regulation valve 27 and the plate supported diaphragm 29 are in bottom position, what means that the regulation valve 27 is fully open.

[0014] At the moment that the safety valve 11 opens or safety valves 11,12 open, gas with a pressure of the inlet pressure inside the gas inlet chamber 15 will flow into compartment or gas chamber 25. With the channel 26 the gas will flow into compartment or gas chamber 28. This will cause the fully open regulation valve 27 to start closing. Gas will flow from compartment 28 into said servo pressure compartment 31 over said inlet orifice 30. At this moment safety valve 12 is open or must be opened.

[0015] As long as the regulated pressure inside said internal gas chamber 17 has not reached its set point, the servo regulation valve 23 will remain closed and servo pressure is built-up in said compartment or gas chamber 31, 32, 33.

[0016] As servo pressure is built-up in compartment 31, this will generate a force on the plate diaphragm 29, which forces the regulation valve 27 to open, or at least slows down the closing of the regulation valve 27.

[0017] The above-described functionality results in quick opening of the gas valve 10.

[0018] The gas valve 10 according to the invention acts as a standard servo regulated gas valve. If there is a request for higher regulated gas pressure, the servo regulator valve 23 closes this leads to an increase of servo pressure in chamber 31,32,33. This results in a further opening of the regulation valve 27, which results in an increase of the regulated pressure in chamber 17. This continues till the new set point is reached. When the request is to obtain a lower outlet pressure, the servo regulator valve 23 opens further, what causes a decrease of the servo pressure, the decrease of servo pressure results in a further closing of the regulator valve 27, what leads to a lower regulated pressure in chamber 17.

[0019] The regulator valve 27 is able to close, because of the inlet pressure that is present under the plate supported diaphragm 29 in chamber 28, which has a larger diameter than the regulation valve.

[0020] Due to the inlet pressure under the plate supported diaphragm 29, there is the possibility to create a flow to open regulation system 22.

[0021] The advantage of the gas valve 10 according to the invention is that by separating the safety valve 11 and the regulation system 22, the regulation valve 27 moves out of the flow so the pressure drop of the gas valve 10 decreases. This means that with the same pressure drop the gas valve 10 according to the invention provides more capacity than a gas valve known from the prior art with the same functionality in place. The increase of capacity of the gas valve 10 takes especially place with a low gas inlet pressure inside said gas inlet chamber 15, because with the smallest gas pressure available, the gas valve 10 will move to its completely open position, if requested by the servo control system 23.

[0022] An advantage is that the regulation system 22 opens very quickly, what will improve the ignition time for the gas burner applications. However, a slow open regulation system can be created by adding a spring between the plate diaphragm 29 and a bottom plate 34 of said housing 13.

[0023] As the regulation system 22 is fully open, when the gas valve 10 is not active, the regulated pressure pick-up point can be used by valve proving systems to measure the pressure.

[0024] Due to the principle of the servomechanism, this gas valve 10 is inlet pressure independent.

Reference numerals:

[0025] 

10

gas valve

11

safety valve

12

safety valve

13

housing

14

solenoid drive

15

gas inlet chamber

16

gas outlet chamber

17

gas chamber

18

closing member

19

valve seat

20

closing member

21

valve seat

22

regulation system

23

servo control system

24

valve seat

25

compartment

26

channel

27

regulation valve

28

gas chamber

29

plate diaphragm

30

inlet orifice

31

gas chamber

32

gas chamber

33

channel

34

bottom plate

Claims

1. Gas valve comprising a first safety valve (11), a second safety valve (12) and a regulation system (22) connected between said first safety valve (11) and said second safety valve (12), characterised in that said regulation system (22) is operated by a servo control system (23).

2. Gas valve according to claim 1, characterised in that a valve seat (24) of said regulation system (22) is profiled.

3. Gas valve according to claim 1 or 2, characterised in that a regulation valve (27) of said regulation system (22) comprises a channel (26), whereby said channel (26) connects a gas chamber (25) positioned above a valve seat (24) of said regulation system (22) with a gas chamber (28) positioned under a diaphragm (29).

4. Gas valve according to claim 3, characterised in that said gas chamber (28) positioned under said diaphragm (29) is connected to a gas chamber (31) positioned above said diaphragm (29).

5. Gas valve according to claim 4, characterised in that said connection is provided by an orifice (30).

6. Gas valve according to claims 3 or 4, characterised in that said gas chamber (31) positioned above said diaphragm (29) is connected to a gas chamber (32) of said servo control system (23).

7. Gas valve according to any of the preceding claims, characterised in that the area of the diaphragm (29) is larger than the area of the regulation valve (27), in order to create a flow to open regulation system (22).

Drawing