GB2548810A

GB2548810A - Gas valve

Info

Publication number: GB2548810A
Application number: GB1604965.2A
Authority: GB
Inventors: Crutchley Steven
Original assignee: PEERLESS GAS CONTROLS Ltd
Current assignee: PEERLESS GAS CONTROLS Ltd
Priority date: 2016-03-23
Filing date: 2016-03-23
Publication date: 2017-10-04
Anticipated expiration: 2036-03-23
Also published as: GB2548810B; GB201604965D0

Abstract

A valve for a domestic gas-burning appliance comprises a body 10 having an inlet 16 and an outlet 20 in communication with a longitudinal internal passage in the body, and a valve spool 30 within the internal passage. The valve spool 30 has two or more longitudinally spaced circumferential O-rings (34, 36, Fig. 7) that form a gas-tight seal between the valve spool 30 and the body 10. A control groove (44, Fig. 7) is formed in an outer surface of the valve spool. A pin 54, fast with the body 10, projects into the control groove 44 of the valve spool 30 and a spindle 60 that is connected with the valve spool 30 projects from the body 10. Rotation of the spindle 60 causes rotation of the valve spool 30 whereupon the pin 55 makes contact with a wall of the control groove 44 to cause linear movement of the valve spool 30 such that the size of a gas flow passage between the inlet 16 and the outlet 20 is varied by the extent to which it is obstructed by the spool.

Description

Gas Valve

The present invention relates to a gas valve. It has particular, but not exclusive, application to a gas valve suitable for use with a domestic gas appliance such as a gas fire or a hob and/or oven of a gas cooker. A gas valve for a domestic gas-burning appliance is provided to allow a user to control the flow of gas to a burner to modulate the power output of the burner. It is preferable that such a valve has features in addition to is basic function: it should feel smooth in operation to give the user an impression of handling a quality product; it should be linear in operation to facilitate accurate control of the flow of gas; and it should have a long service life, since domestic gas appliances may be in service for decades.

Conventional gas valves have a number of disadvantages. They rely on grease to provide gas-tight seals between components of the valve. The grease can, over time, diy out, which means that operation of the valve can become stiff, and eventually the seals may leak. Additionally, they may have components, such as tapered plugs, that require machining to fine tolerances and machining a groove onto a cone is difficult This complicates and increases the cost of manufacture.

An aim of this invention is to provide an improved valve for use in controlling a gas-burning appliance.

To this end, the present invention provides a control valve optionally for a domestic gasburning appliance that may include some or all of the features herein described.

This invention provides a valve for a domestic gas-burning appliance comprising some or all of: a. a body having an inlet and an outlet in communication with a longitudinal internal passage of the body; b. a valve spool within the internal passage that, the valve spool having: i. two or more longitudinally spaced circumferential O-rings that form a gas-tight seal between the valve spool and the body; and ii. there being a control groove formed in an outer surface of the valve spool; c. a pin, fast with the body, projecting into the control groove of the valve spool; d. a spindle that is connected with the valve spool and which projects from the body; wherein e. rotation of the spindle to thereby causes rotation of the valve spool whereupon the pin makes contact with a wall of the control groove to cause linear movement of the valve spool, such that the size of a gas flow passage between the inlet and the outlet is varied by the extent to which it is obstructed by the spool.

The presence of the O-rings avoids the need to provide closely-fitting components and imparts minimal friction between moving parts so making the valve easy to use.

Advantageously, the O-rings are formed from a fluoropolymer elastomer, which has advantageous durability and sealing characteristics. A valve embodying the invention may further include a bypass channel that connects the inlet to a pilot outlet. The pilot channel may be closed by a valve that can be opened by linear movement of the spindle. A valve embodying the invention may further comprise a safety shut-off that is operable to selectively prevent or allow flow of gas from the inlet to the outlet The valve may further comprise a solenoid assembly which, in an energised state, causes the safety shut-off to allow flow of gas from the inlet to the outlet and in a de-energised state causes the safety shut-off to prevent flow of gas from the inlet to the outlet In addition, the valve may include a thermal sensor that is disposed to sense the presence or absence of a burning pilot light, and energise the sensor when the pilot light is burning.

Typical embodiments of the invention are a control for a burner in a gas cooker, an oven in a gas cooker or hob, or a control for a gas fire.

From a second aspect, this invention provides a gas-burning appliance incorporating one or more vales embodying the first aspect of the invention.

An embodiment of the invention will now be described in detail, by way of example, and with reference to the accompanying drawings, in which:

Figures 1 to 3 are external views of a gas valve being an embodiment of the invention;

Figure 4 is an external view of the gas valve of Figures 1 to 3 with an end cap removed;

Figure 5 is a part cut-away view of the embodiment of Figures 1 to 4;

Figure 6 is a detail of the cut-away section of Figure 5;

Figures 7 and 8 are alternative views of a valve spool being a component of the embodiment of the preceding figures;

Figures 9 and 10 are exploded views of the embodiment of Figures 1 to 4; and Figure 11 is a sectional view of the embodiment of Figures 1 to 4.

The valve comprises a body 10 formed, in this example, as one piece from a machined alloy billet The body has a bore extending through it in a direction that will be referred to as the main axial direction of the body 10, the bore extending from a fist end that will be referred to as the spindle end 12, and a second end that will be referred to as the mag valve end 14. The choice of nomenclature will become apparent in due course. The bore has a step reduction in diameter, such that it is smaller at the mag valve end 14 than at the spindle end 12.

An externally-threaded cylindrical boss 16 projects from the body 10, angled with respect to the axis and extending along an inlet axis outwards towards the mag valve end 14. A passage extends through the boss 16 to intersect with the larger-diameter part of the bore within the body 10. The boss 16 forms a gas inlet connector for the valve. A gas outlet for the valve is formed by a transverse spigot portion 20 of the body 10. A passage 26 extends through the boss along an outlet axis to intersect with the bore within the body. The boss 16 and the spigot 20 are arranged such that the inlet axis, the outlet axis and the main axis intersect at a common point. Lugs 22 project from the spigot 20, each having a bore that extends parallel to the outlet axis, whereby the valve can be secured to an appliance for use. A valve spool 30 is located within the bore. In this embodiment, the valve spool comprises a unitary metal core 32 upon which first and second O-rings 34, 36 are carried. In this embodiment, the O-rings are formed from a fluoropolymer elastomer such as is sold under the name "Viton” (RTM). An axial bore extends through the core 32. The core 32 has a central section 38 with a cylindrical outer surface. A circumferential groove 42 is formed in the central section 38 to retain the first O-ring 34. A bypass channel 28 extends transversely from an external surface of the body 10 to intersect with the bore to the inlet side of the valve spool 30. The bypass channel 28 is partially obstructed by an adjuster screw 24 that can be used to control the effective area of the bypass channel 28. A spindle connection portion 40 extends from the central section 38. The spindle connection portion 40 is shaped as a cylinder of smaller diameter and coaxial with the central section 38. A transverse slot 48 is formed in the spindle connection portion 40, extending from a free end of the spindle connection portion 40 to a small distance into the central section 38. A spigot 50 projects from the central section. The spigot 50 is shaped as a cylinder of smaller diameter and coaxial with the central section 38, and is also of lesser diameter than the spindle connection portion 40. A circumferential groove 52 is formed in the central section to retain the second 0-ring 36. A control groove 44 is also formed in the outer surface of the central section 38. The control groove 44 is open to a free end of the central section 38 adjacent to the spigot 50. From there, a first length of the control groove 44 extends axially towards the spindle connection portion 40. The control groove 44 then turns through a right angle to extend circumferentially around the outer surface of the central section 38, in a curve so as to first approach and then recede from the spigot 50. Finally, the control groove 44 extends circumferentially around the outer surface of the central section 38 at a constant distance from the spigot 50.

The valve spool 30 is located within the bore of the body 10, the spigot 50 being within the smaller diameter part of the bore and the central section 38 being in the larger diameter part of the bore, with the first and second O-rings 34, 36 being axially to opposite sides of the outlet passage 26. The O-rings 34, 36 form a gas-tight seal with the bore. A pin 54 is passed through a hole 56 in the body 10 to pass into the bore whereby an inner end portion of the pin 54 enters the control groove 44 of the valve spool 30. It will be understood that there is a cam action between the pin 54 and the control groove 44 whereby rotation of the valve spool 30 causes the valve spool 30 to move axially within the body 10.

The valve further includes an elongate spindle 60 disposed axially within the body 10. The spindle 60 is predominantly cylindrical, with an outer diameter that is a close sliding fit within the bore of the valve spool 30. A flat 62 is formed in an outer end portion to which a control knob (not shown] can be fixed. A pin 64 passes through a transverse bore 66 of the spindle 60 and projects radially from the spindle. The projecting portions of the pin 64 are received within the transverse slot 40 of the valve spool 30, such that rotation of the spindle 60 causes rotation of the valve spool 30. An end portion of the pin 64 rotates within a recess in an end potion of the bore of the body 10 that partly surrounds the spindle, rotation of the spindle 60 being limited to approximately 270° because the pin 64 cannot be rotated beyond the extent of the recess. The spindle 60 is retained in place by an end plate 66 secured by bolts 68, these being absent from Figure 4. A drive pin 80 extends from the spindle 60 through the valve spool. The drive pin 80 carries a collar that confines a compression spring 84 between itself and the spindle 60. A thermoelectric valve 70 (commonly referred to as a "mag valve”] is secured to the end of the body opposite to that from which the spindle 60 projects. The thermoelectric valve includes a shut-off plunger 74, which is biased by a compression spring towards the valve spool 30. When the thermoelectric valve 70 is de-energised, the shut-off plunger 74 is urged by the spring against a sealing surface that surrounds the bore within the body 10, forming a seal against it, and thereby preventing any flow of gas from the inlet 16 through the bore of the body 10 towards the valve spool 30. Energisation of the thermoelectric valve70 by a thermocouple (not shown] causes the plunger 74 to be held away from the spool 30 as shown in Figure 11, against the force of the spring, whereupon gas can flow into the bore of the body 10 from the inlet 16.

With the valve in the "off" position, the pin 54 is close to the open end of the control groove 44. To turn the valve on, the spindle 60 is manually driven into the valve body 10 (to the right as shown in Figure 11) thereby moving the valve spool 30 axially. The pin 54 enters the control groove, axial movement being limited by the pin 54 reaching the right-angle of the control groove 44. The drive pin 80 makes contact with the shut-off plunger 74 so lifting it from the sealing surface. In this position, a small amount of gas can pass from the inlet passage into the bore of the body and then into the bypass channel 28 to supply gas to a pilot light, and a spark igniter is operated to light the pilot light Once the pilot light has been lit, it heats the thermocouple and the thermoelectric valve 70 is energised to hold the shut-off plunger 74 away from the sealing surface such that the flow path for gas into the bore is maintained open so long as there is a flame.

Gas can now flow from the inlet 16 to the valve spool 30. Further rotation of the spindle 60 causes the valve spool 30 to move axially, as described above. Initially, the spool is moved to a position in which there is minimal obstruction of the inlet 16 and outlet 20 of the valve, so allowing a maximum flow of gas to a burner. Continued rotation causes gradual obstruction of the flow path, with the effect of turning down the flow of gas to the burner.

Claims

1. A valve for a domestic gas-burning appliance comprising: a. a body having an inlet and an outlet in communication with a longitudinal internal passage of the body; b. a valve spool within the internal passage that, the valve spool having: i. two or more longitudinally spaced circumferential O-rings that form a gas-tight seal between the valve spool and the body; and ii. there being a control groove formed in an outer surface of the valve spool; c. a pin, fast with the body, projecting into the control groove of the valve spool; d. a spindle that is connected with the valve spool and which projects from the body; wherein e. rotation of the spindle to thereby causes rotation of the valve spool whereupon the pin makes contact with a wall of the control groove to cause linear movement of the valve spool, such that the size of a gas flow passage between the inlet and the outlet is varied by the extent to which it is obstructed by the spool.

2. A valve according to claim 1 which further includes a bypass channel that connects the inlet to a pilot outlet

3. A valve according to claim 2 in which the pilot channel is closed by a shut-off valve that can be opened by linear movement of the spindle.

4. A valve according to any preceding claim further comprising a safety shut-off that is operable to selectively prevent or allow flow of gas from the inlet to the outlet

5. A valve according to claim 4 further comprising a thermoelectric valve assembly which, in an energised state, causes the safety shut-off to allow flow of gas from the inlet to the outlet and in a de-energised state causes the safety shut-off to prevent flow of gas from the inlet to the outlet

6. A valve according to claim 5 which includes a thermal sensor that is disposed to sense the presence or absence of a burning gas flame, and energise the thermoelectric valve when the gas flame is burning.

7. A valve according to any preceding claim in which the O-rings are formed from a fluoropolymer elastomer.

8. A valve according to any preceding claim that is a control for a burner in a gas cooker.

9. A valve according to any preceding claim that is a control for a gas oven.

10. A valve according to any one of claims 1 to 7 that is a control for a gas fire.

11. A valve for a domestic gas-burning appliance substantially as herein described with reference to the accompanying drawings.

12. A gas-burning appliance incorporating one or more vales according to any preceding claim.