GB2362706A - Gas control valve - Google Patents

Abstract

The valve comprises a valve block 1 having an actuator 5 slidable in a channel which has lateral branches for a gas inlet 20, a pilot gas outlet 21 and a main flow outlet 22. A solenoid 11 operated shut off valve 26 is displaced by sliding movement of a hollow valve member at the distal end of actuator 5, thus supplying gas to pilot outlet 21. This may be via apertures 29 on the valve member corresponding with apertures (32, fig 3) in pilot sleeve 10. The solenoid is energised by a thermocouple associated with the pilot flame. Sliding movement of the valve member in the direction away from valve 26 varies the gas flow from the inlet to the main outlet, this may be by exposing more of apertures 29 to the main outlet. Further movement in this direction cuts off gas flow to the pilot outlet 21 as the last aperture 29 moves past the aperture (32) in sleeve 10. Cutting off gas to the pilot leads to the solenoid valve closing inlet 20 and extinguishing the burner.

Description

2362706 GAS CONTROL VALVE This invention relates to gas control valves

and, more particularly, to linear action gas control valves for use in domestic appliances such as gas fires where it is desirable using a single control to turn the gas fire on or of f and to vary the flame level in the burner to a desired degree between a low flame and a maximum setting.

1 0 EP-A-0884531 discloses a valve of this general type having a valve block and an axially slidable member located in a channel in the block. At one end of the channel is located a solenoid including an actuatable member which carries a sealing member cooperating with a valve seat to shut off gas flow entirely or allow gas to pass from a gas supply into the channel, and a plurality of further valve seats located along the channel which can be successively opened to allow increasing gas flow.

Manufacture of the valve illustrated in EP-A-0884531 is complex particularly as each increase in gas flow requires a closure member to be moved away from a corresponding valve seat, so that the number of possible main flame settings corresponds essentially to the number of valve seats. Thus, the variability of setting desired by users, 1 which should desirably be smoothly variable f rom a low flame setting to the maximum is essentially stepped in a very small number of steps unless the valve is equipped with several valve seats, leading to an unacceptable rise in manufacture and assembly costs.

We have now found that improved linear action gas control valves may be constructed allowing a much smoother variation in flame level by the use of a slide valve system which, apart from a main valve seat to control gas flow to the burner of the appliance is otherwise relatively smoothly able to vary the gas flow by relatively continuously increasing the cross-sectional area of the passage within the valve leading from the gas supply to the main burner connection.

According generally to the present invention there is provided a linear action gas control valve for controlling gas flow to a burner, the valve comprising a valve block and an actuation member axially slidable in an elongate channel therein, the channel being provided with lateral branches for gas inlet, pilot gas outlet and main outlet f lows, and including a solenoid operated shut-of f valve adapted when not activated to engage a valve seat adjacent the gas inlet branch and located to one end of the channel, and wherein the control valve includes a member slidable axially in the channel and adapted as it approaches one end position to displace a member closing the valve seat and in its other end position to shut off gas flow to the pilot outlet branch, and arranged to vary the gas flow from inlet to main outlet in accordance with its position along the channel over a range of movement intermediate its end positions.

Preferably the elongate member consists for part of its length of a hollow tube open at one end and having a number of lateral bores, the hollow tube cooperating with a close- fitting sleeve member located in the channel and having a port in the wall of the sleeve member of size sufficient to enable a pilot flow of gas to pass when the aperture in the sleeve member coincides with one or more of the apertures in the elongate member. By locating the apertures in the elongate member appropriately as well as by dimensioning the sleeve member appropriately, the desirable gas flow characteristics may be achieved easily and simply in a valve with a few moving parts and which may 10 be designed to be simple to manufacture and assemble.

An example of a gas control valve in accordance with the present invention is illustrated in the accompanying drawings in which:

is Figure 1 is an axial section through the valve along the lines A-A in Figure 2, Figure 2 is an end view of the valve, and Figure 3 is a perspective view on an enlarged scale of one of the components of the valve.

Referring first to Figures 1 and 2, the valve is principally constructed of a valve block 1 having an elongate passage running from one end to another and, running transversely to the passage, three bores threaded at their outer ends to enable connection of a main gas supply to bore 20, a pilot burner to bore 21 and a main burner to bore 22. Bore 20 connects to a widened end of the channel running through the block adjacent a valve seat 25. Located in the widened end of the channel is a standard solenoid 11 with a sealing disc 26 which, when the solenoid is not actuated, is sprung against seat 25, thus preventing gas flow along the channel. The solenoid 11 is located in the channel by means of a gland nut 12 which seals the solenoid in the channel and prevents gas leakage.

I Downstream (in terms of gas flow) from the seat 25, the channel running through block 1 has a narrow section followed by three successively wider sections. The narrow section is of diameter matching that of an actuation member 5 which can slide in it, and which can also slide in a sleeve 10 located in the next wider section into the wall of which the bore 21 debouches. In the next wider section, the elongate member 5 is surrounded by space, and bore 22 connected to the main burner in use debouches into this next wider section. Finally, into the widest section (the right hand end of the block in Figure 1), a gland nut 6 is screwed, gland nut 6 having an internal o-ring 7 sealing against the exterior of elongate member 5.

Located around elongate member 5 outside of block 1 is a microswitch assembly 2 which is fixed relative to block 1 in the gland nut 6 and which also serves as a support for one end of a compression spring 3 surrounding elongate member 5, the other end of which may abut a circlet 4 clipped on to elongate member 5 which, as shown, has the form of a circular rod.

The end of the elongate member 5 to the left as shown in Figure 1 is counterbored so that the end constitutes a hollow tube, the hollow tube having in its walls a plurality of axially spaced apertures, one aperture denoted 28 in Figure 1 being located adjacent the left hand end of the elongate member 5 and the other apertures denoted 29 in Figure 1 being spaced along the member as shown.

Although, as appears from the sectional drawing of Figure 1, the elongate member has one aperture 28 and seven apertures 29, in practice the elongate member has two oppositely lying apertures 28 and in all fourteen apertures 29 which, as explained below, regulate the main gas flow.

The travel of elongate member 5 to the left is limited by the leftmost position of the valve disc 26 on solenoid 11.

Its travel to the right is limited by the engagement of a wire ring 9 which is engaged by spring force around elongate member 5 and which is designed to engage in a chamfered aperture in a washer 8 which is located around elongate member 5 and which, by means of a compression spring 40 set in a counter-bore in gland nut 6 is normally held against a shoulder at the end of the widest portion of the channel into which gland nut 6 is threaded.

The sleeve 10 is illustrated in more detail in Figure 3. It is an integral plastics moulding consisting of a sleeve of internal bore 33 matching the external shape and size of the elongate member 4 and which has two annular beads 30 and 31 which are dimensioned to be a tight fit in the section of the channel in block 1 into which bore 21 debouches. Sleeve 10 also has a pair of oppositely lying apertures 32 which can register with apert ures 29 in the elongate member 5.

It is important that gas control valves do not leak and it is accordingly a customary requirement for any such valve to provide a so-called test point, i.e. a connection to which a test meter or the like may be applied. This can be used when setting up the appliance to ensure appropriate settings of the valve and other adjustable components. Also, if source of pressurised gas is applied to the test point with the gas inlet and outlets to the gas control valve blanked off, any gas leakage from the interior of the valve block can be detected. For this purpose, a further bore is provided in block 1 debouching into the widest but one portion of the channel through the block slightly upstream of bore 22. Its position is just to the left of ring 9 as shown in Figure 1 and a suitable test point sleeve 13 is screwed into the block 1 and sealed with respect thereto. The outer end of test point sleeve 13 is normally blanked of f in use by a sealed cap 15 which is removed when it is desired to test the device.

When installed, main gas supply connection is made to bore 20, bore 21 is connected to a pilot burner and bore 22 to a main burner, e.g. in a domestic gas fire. The solenoid 11 is connected to a thermocouple arranged adjacent the pilot burner and designed, when heated, to produce sufficient current to actuate the solenoid and retain valve disc 26 in the position shown in Figure 1, i.e. away from seat 25. A suitable igniter system, e.g. an electric spark generator, is located adjacent the pilot burner and connected to microswitch 2.

The operation of a gas fire incorporating the gas control valve illustrated in the drawings will now be described. In the normal starting condition, i.e. with the gas fire switched off, a spring in solenoid 11 holds valve disc 26 against seat 25 and thus stops any gas flowing from the main gas supply 20. The elongate member 5 can be in any position from slightly to the left of that shown in Figure 1 to its maximum travel to the right. There is simply no gas flow, so it is not relevant where the control elongate member 5 is set.

In order to light the gas fire, elongate member 5 is moved to the furthest possible travel to the left as shown in Figure 1. The end of member 5 contacts valve disc 26 and as member 5 is urged to the left, disc 26 may be moved away from seat 25, thus allowing gas to flow from bore 20 via holes 28 into the hollow end of elongate member 5 and out through those holes 29 which are registered with apertures 32 in pilot sleeve 10. As can be seen, there is an annular gap between the portion of the main channel into which pilot sleeve 10 is press fitted and the outer diameter of the beads on sleeve 10, and this enables gas to flow through the annular channel and then into bore 21 and thence to the pilot light. The movement of elongate member 5 to its maximum travel to the left actuates microswitch assembly 2 which, via the circuit to which it is connected, 1 is then ignites the pilot flame. Once the flame is ignited, the thermocouple adjacent the pilot flame actuates solenoid 11 to hold valve disc 26 away from seating 25 and accordingly when member 5 is no longer urged to its most leftward position, it is retracted by spring 3 to a position slightly to the left of that drawn in Figure 1 in which gas can still flow from bore 20 through seating 25 and now into the open end of elongate member 5, out through the apertures 29 registered with the apertures 32 in the sleeve 10 and thus maintain the pilot flame lit. in this position, there is no gas flow to the main burner via bore 22 since all of the apertures 29 are located within sleeve 10, or within the portion of the channel shown immediately to the left of sleeve 10 in Figure 1.

If it is desired to light the main burner, member 5 is now moved to the right as shown in Figure 1, thus moving the rightmost apertures 29 into the broader section of the channel in block 1 into which bore 22 debouches.

Initially, gas can flow only through a pair of the apertures 29 in member 5, but the flow of gas which then reaches the main burner is sufficient to enable the main burner to be lit by the pilot flame, albeit at a low level setting. As member 5 is moved f urther to the right, however, more of the apertures 29 emerge from the right hand end of pilot sleeve 10, so more and more gas can flow from inlet 20 to the main burner connected to bore 22. As the member 5 is moved to the right, so ring 9 approaches washer 8 and the maximum setting is achieved when ring 9 abuts washer 8 and nests into the chamfered inner circumference thereof. This end point can be clearly felt by the user of the appliance, but this does not constitute the full extent of the rightwards travel of member 5, as washer 8 is sprung by spring 40 as explained above. it does, however, constitute the maximum flow position with the rightwards set of apertures 29 now all open to the part of the channel into which bore 22 debouches and the left 8 hand end one of the apertures 29 still registered with aperture 32 in the pilot sleeve 10.

The main burner level can be turned up or down at will by moving the member 5 to the right or left respectively.

When it is desired to turn off the fire, the member 5 is moved to the right to engage ring 9 in washer 8 and then moved further to the right with compression of spring 40.

This movement causes the left hand end aperture 29 to move past aperture 32, but the dimensions are such that aperture 28 does not reach aperture 32, so, at this point, aperture 32 is sealed and no gas now flows to the pilot burner via bore 21, so the pilot burner extinguishes. Once the pilot burner has extinguished, the thermocouple which it is normally arranged to heat stops providing current to the solenoid 11, so solenoid 11 deactuates and, because of its own internal spring, moves valve disc 26 to the right as shown in Figure 1 to abut seating 25. As soon as this occurs, the main gas flow via bore 20 is shut off and the main flame connected to bore 22 simply extinguishes. Release of the member 5 moves it back (under the action of spring 40) slightly to the left, but not very much.

Nothing now happens until the member 5 is moved to its leftmost position as described above when someone wants to relight the fire.

A particular advantage of the valve construction in 30 accordance with the present invention is that the relationship between the axial position of member 5 and the gas flow to the main burner may be customised very simply by providing an appropriate pattern of apertures 29 of appropriate size. Because the overall flow passage may be increased in small steps as each aperture comes into the broad section of the channel into which bore 22 debouches, the degree of control which can be exercised can be very 1 fine if called for, and essentially continuous smoother variation of main burner level thereby easily achieved. As can be seen by reviewing the construction shown in the example of a valve for a gas fire in accordance with the invention illustrated in the accompanying drawings, the manufacture is simple and straightforward, as is assembly. This leads to reliable operation which is sustained over a long service life.

In practice, the right hand end of actuation member 5 may be connected to any appropriate actuation knob or lever, either directly or e.g. via a simple mechanical linkage.

Claims (3)

1. A linear action gas control valve for controlling gas flow to a burner, the valve comprising a valve block and an actuation member axially slidable in an elongate channel therein, the channel being provided with lateral branches for gas inlet, pilot gas outlet and main outlet flows, and including a solenoid operated shut-off valve adapted when not activated to engage a valve seat adjacent the gas inlet branch and located to one end of the channel, and wherein the control valve includes a member slidable axially in the channel and adapted as it approaches one end position to displace a member closing the valve seat and as it approaches its other end position to shut off gas flow to the pilot outlet branch, and arranged to vary the gas flow from inlet to main outlet in accordance with its position along the channel over a range of movement intermediate its end positions.

2. A gas control valve according to claim 1 wherein the elongate member consists for part of its length of a hollow tube open at one end and having a number of lateral bores, the hollow tube cooperating with a closefitting sleeve member located in the channel and having a port in the wall of the sleeve member of size sufficient to enable a pilot flow of gas to pass when the aperture in the sleeve member coincides with one or more of the apertures in the elongate member.

3. A linear action gas control valve substantially as hereinbefore described with reference to the accompanying drawings.

1 i; 1 11.