GB2350884A

GB2350884A - Gas flow control using manually operable cam

Info

Publication number: GB2350884A
Application number: GB9913555A
Authority: GB
Inventors: Philip John Hollingsworth
Original assignee: Stoves Group PLC
Current assignee: Stoves Group PLC
Priority date: 1999-06-11
Filing date: 1999-06-11
Publication date: 2000-12-13
Also published as: GB9913555D0

Abstract

A gas appliance is disclosed which includes a gas burner, a valve assembly 208 and a cam 202. The cam 202 is manually moveable and configured to operate a cam follower 203 which is attached to a sliding element 207 within the valve assembly. The valve assembly may include an electromagnet (310) which forms a part of a flame failure device. Movement of lamina 201 causes cam 202 operation of the valve assembly to control the gas flow rate.

Description

2350884 Gas Appliances The present invention relates to a gas appliance

including a gas flow control, operable by a manually operable cam.

It is known to provide within a gas appliance a manually operable linear valve assembly which is operated by a user pushing in a button when the appliance is to be started. The push button may also be connected to a spark ignition unit, in order to ignite a burner. Such valve assemblies are generally only used as on/off valves and include an electromagnet which forms a part of a flame failure device. Therefore, they allow a maximum gas flow rate to the bumer or zero flow rate: they are not used to provide a variable flow rate. Consequently, an additional gas valve has to be placed in series with the valve assembly to provide a means of varying the gas flow.

According to a first aspect of the present invention there is provided a gas appliance including gas burning means, a gas flow control means and a manually operable cam, wherein said flow control means is configured to be operable by said cam.

In a preferred embodiment of the present invention the cam is configured to be linearly moveable and such that a linear movement of said cam provides a linear movement of an element located within said flow control means. Preferably, the linear movement of said cam provides a reduced linear movement of said element. Furthermore, the flow control means is configured to allow a variable rate of gas flow.

In a preferred embodiment the gas appliance is a fire. Preferably, said fire is configured to be inset into a wall.

According to a second aspect of the present invention there is provided a method of manufacturing a gas appliance including the steps of 2 providing a gas burning means, providing a manually operable cam, and configuring a gas flow control means to be operable by said cam.

The invention will now be described by way of example only with reference to the following drawings.

Figure 1 shows an inset solid fuel effect gas fire 101 which embodies the present invention; Figure 2 provides a cutaway view of the gas fire shown in Figure 1; Figure 3 provides a cross-sectional view of the valve assembly and the sliding lamina shown in Figure 2; Figure 4 shows an exploded rear view of the frame surround and lamina shown in Figure 2; An inset solid fuel effect gas fire 101, which embodies the present invention is shown in Figure 1. The fire is inset in a wall 102 of a room and has a coal effect portion 103, which forms part of a main burner. In operation, gas flows through the coal effect portion and bums above said portion to provide an appearance similar to that of burning coal.

The fire has a frame surround 104 which provides an attractive embellishment to the fire but also supports a slide control 105. By sliding the control 105 up or down a user is able to regulate the size of flame burning in the fire. If the slide control is placed in a fully up position, the flame burning above the coal effect portion is maximised. If the slide control is placed in a fully down position, the main burner flame is extinguished. However, when the slide control is in the fully down position, a pilot flame remains burning within the fire and raising the slide control will re-light the main burner. The pilot burner is located behind an upper grate element 106 and an inner plate (not shown).

In general, the pilot flame is left to bum when the fire is not being 3 used. For example the pilot may be left to bum over-night. However, on occasions when it is expected that the fire will not be used for a prolonged period, the user may wish to turn off the pilot light. In order to extinguish the pilot flame, the slide control is raised from the fully down position and an off switch is depressed. The off switch is accessed by removing the base of the grate 107.

Subsequently, the pilot flame must be re-ignited before the fire may be re-used. In order to ignite the pilot flame, the slide control is lowered to the fully down position and an on-switch is depressed. The on-switch is also accessed by removing the base 107.

A cutaway view of the gas fire shown in Figure I is provided in Figure 2. The upper grate element, the base of the grate and the inner plate have all been removed. In addition, a part of the frame surround has been cut away allowing a lamina 201 to be seen. The lamina is laser cut from a sheet of 'nylon 66' and includes the slide control 105. The lamina is mounted within the frame surround so that it may only slide up and down.

The lower end of the lamina is shaped to form a cam 202 and the cam pushes against a cam follower 203. The cam follower is also cut from a sheet of nylon 66 and is manufactured in a similar way to the lamina.

The cam follower is mounted to a supporting plate 204 by two screws 205, which pass through two corresponding slots 206 in the cam follower. The slots are configured to allow the cam follower to slide in a direction parallel to its longest side. The cam follower is attached to a push rod 207 which forms a part of a valve assembly 208.

The valve assembly used is produced by MP Fabrica Rubinetti srI, (of Italy) under the model number 200499. The valve assembly has an inlet, a main outlet, a pilot outlet and an electromagnet which forms part of a 4 flame failure device. Valve assemblies of this type are found in conventional appliances. However, this type of valve assembly is conventionally only used to switch on and off, the gas supplies to the main burner and pilot burner: the regulation of the quantity of gas to the main burner is performed by a second valve in series with the assembly. The valve assembly 208 is supplied with natural gas via a pipe 209 and is connected to two outlet pipes 210 and 211. The outlet pipe 210 is also connected to the main burner and the outlet pipe 211 is connected to the pilot burner 212.

A thermocouple 213 is mounted adjacent to the pilot burner, such that it is heated by the pilot flame when lit. The thermocouple is electrically connected to an electromagnet located within the valve assembly. The electromagnet is wired in series with the off-switch 214. The off-switch is a micro-switch of a type which is closed until it is pressed. Therefore, pressing the off-switch opens the circuit connecting the thermocouple and electromagnet.

The on-switch 215 is a micro-switch of a type which is open until it is pressed. Pressing the on-switch completes a circuit connecting a spark ignition unit (not shown) and an ignition electrode 216.

A cross-sectional view of the valve assembly and the sliding lamina shown in Figure 2, is provided in Figure 3.

The slide control is shown in the fully up position and both the main and pilot burners are extinguished. Gas is supplied to the valve assembly via an inlet port 301. However, the gas is restricted from flowing through the valve assembly by an inlet seating element 302 and so gas cannot flow into pipes 210 and 211.

The fire is started by lowering the slide control, and hence the lamina 201 to the fully down position (indicated by dotted outline 303). As a result the cam follower is pushed by the cam and this in turn pushes the push- rod further into the valve assembly. The movement of the push-rod compresses a spring (not shown) within the valve assembly. An outlet sealing element 304, attached to the push-rod, is therefore moved from its initial position, as shown, to a new position. (The left-most surface of the element 304 attains a new position indicated by the dotted line 305). In the new position the outlet sealing element prevents the possible passage of gas through an outlet port 306, into pipe 210 and so no gas may reach the main burner. During the movement of the push-rod, a pin 307, which is attached to the push-rod, pushes against the inlet sealing element. The inlet sealing element is consequently moved to a position whereby gas may flow from the inlet port and into the pipe 211. Gas is therefore supplied to the pilot burner. The movement of the inlet sealing element compresses a second spring (not shown) within the valve assembly. In addition, by means of a connecting pin 308, a metal disc 309 is pushed towards the electromagnet 310.

The user now presses the on-switch, which causes the ignition unit to produce a spark at the ignition electrode. The spark ignites the gas which is present at the pilot burner and so establishes a pilot flame. The heat from the pilot flame produces a current which energises the electromagnet and a resulting magnetic field attracts the metal disc to the electromagnet.

The use of the valve for igniting the pilot flame is therefore similar to its use in conventional appliances.

The slide control, and hence the cam, is then raised by the user to an intermediate position. The cam follower continues to follow the cam since the sprung push rod is pushing against it. The push-rod is therefore allowed to spring back out by an amount determined by the intermediate position of the slide control. The pin 307 stops pushing against the inlet sealing element, but 6 the connecting pin and metal disc hold the inlet seating element in place. This is possible because the electromagnet holds the metal disc in place. The inlet port therefore remains open.

Since the outlet sealing element is attached to the push-rod, it is moved to an intermediate position determined by the intermediate position of the slide control. The intermediate position of the outlet sealing element allows gas to escape through the outlet port but also causes a degree of obstruction to gas flow at the outlet port. Gas which escapes through the outlet port is piped to the main burner and ignited by the pilot flame and so a main burner flame is established. If the intermediate position of the slider is high, then the degree of obstruction at the outlet port is low. The rate of gas flow through the outlet port is determined by the degree of obstruction and thus the rate at which gas reaches the main burner is determined by the intermediate position of the slide control. Therefore, by manual adjustment of the intermediate position of the slide control, the size of the main burner flame is adjusted.

In order to vary the size of main burner flame from zero to a maximum, the push-rod only needs to be moved by 12 millimetres. However, an angle 311, between an angled side 312 and a vertical side 313 of the cam, is such that a 100 millimetre movement of the slide control is required to produce the 12 millimetres of movement by the push-rod. The relatively large movement required by the slide control enables the user to adjust the flame more easily.

The lamina and frame surround shown in Figure 2 are also shown in the exploded rear view provided by Figure 4. A right vertical portion 401 and part of a top horizontal portion 402 of the frame surround are shown.

The portions 401 and 402 are manufactured from anodised aluminium alloy extrusions. The portions are attached to each other by means of a steel 7 corner plate 403 which slots into them and has an interference fit within them. A similar corner plate is used to attach portion 402 with a left vertical portion. A rectangular steel plate 404 is then slotted into the lower end of the vertical portion 401 and a similar plate is slotted into the left vertical portion. A lower slot 405 is milled into the right vertical portion 401 and is configured to accept the cam follower. An upper slot 406 is also milled into the portion 401 and is configured to accept the slide control portion 105 of the lamina 201. The lamina is dimensioned to be a good sliding fit between the side walls 407 and 408 of the portion 401.

The lamina is positioned inside the left vertical portion with the slide control projecting through the upper slot 406. A steel strip 409 is positioned over the lamina and attached to the corner plate and rectangular plate by means of welds 410. The lamina is thus confined within the frame but able to slide up and down.

is Bar magnets 411 are attached to the steel strip 409 close to its top and bottom ends. The bar magnets are subsequently used for attaching the frame to a back plate which is located against the wall 102 of the room and surrounding the fire. The back plate is made from 1.2 millimetre thick steel and is configured to fit within outer walls, such as the wall 407 of the frame.

The front face of the back plate is positioned in front of the wall 102, by a distance which is slightly greater than 1.2 millimetres steel thickness. The distance in excess of the 1.2 millimetres is due to a thin foam strip which is sandwiched between the back plate and the wall.

The overall thickness of the portions 401 and 402 is 10 millimetres and corresponds to the length of an edge 412. The height of the inside of the wall 407 is 8 millimetres. The lamina has a thickness of 2 millimetres, the steel components 403, 404 and 408, all have a thickness of 1.2 8 millimetres and the bar magnets are 4 millimetres thick. Therefore, the total thickness of the back plate, the steel components and the magnets is less than 8 millimetres (the inside wall height). So when the frame is mounted to the back plate, the frame walls, such as wall 407, butt up to the wall 102.

The inner walls of the frame, such as wall 408 are configured to have a shorter height than the wall 407, so that they do not stop the outer walls from butting up against the wall 102.

Therefore, when the frame surround is mounted to the back plate, the frame surround extends from the wall by a distance of only 10 millimetres.

9

Claims

Claims

A gas appliance including gas burning means, a gas flow control means and a manually operable cam, wherein said flow control means is configured to be operable by said cam.
2. A gas appliance according to claim 1, wherein said cam is configured to be linearly moveable.
3. A gas appliance according to claim 2, wherein said cam is configured such that a linear movement of said cam provides a linear movement of an element located within said flow control means.
4. A gas appliance according to claim 2, wherein said cam is configured such that a linear movement of said cam provides a reduced linear movement of an element located within said flow control means.
5. A gas appliance according to any of claims 1 to 4, wherein said flow control means is configured to allow a variable rate of gas flow.
6. A gas appliance according to any of claims 1 to 5, wherein said flow control means includes a linearly operable gas valve.
7. A gas appliance according to any of claims I to 6, wherein said flow control means includes two linearly operable gas valves.
8. A gas appliance according to any of claims I to 7, wherein said flow control means includes a valve configured to allow a variable rate of gas flow.
9. A gas appliance according to any of claims I to 8, wherein said flow control means includes an electromagnet.
10. A gas appliance according to any of claims I to 9, wherein said cam is located within a frame surround of said appliance and said frame surround is mountable to a wall.
11. A gas appliance according to any of claims I to 10, wherein said gas appliance is a fire.
12. A gas appliance according to any of claims I to 11, wherein said gas appliance is a fire and said fire is configured to be inset into a wall.
13. A gas appliance according to any of claims I to 12, wherein said cam is made from a plastics matedal.
14. A method of manufacturing a gas appliance including the steps of providing a gas burning means, providing a manually operable cam, and configuring a gas flow control means to be operable by said cam.
15. A method of manufacturing a gas appliance according to claim 114, wherein said cam is configured to be linearly moveable.
16. A method of manufacturing a gas appliance according to claim 14 or claim 15, wherein said cam is configured such that a linear movement of said cam provides a linear movement of an element located within said flow control means.
17. A method of manufacturing a gas appliance according to any of claims 14 to 16, wherein said cam is configured such that a linear movement of said cam provides a reduced linear movement of an element located within said flow control means.
18. A method of manufacturing a gas appliance according to any of claims 14 to 17, wherein said flow control means is configured to allow a variable rate of gas flow.
19. A method of manufacturing a gas appliance according to any of claims 14 to 18, wherein a linearly operable gas valve is included within said flow control means.
20. A method of manufacturing a gas appliance according to any of claims 14 to 19, wherein two linearly operable gas valves are included within said flow control means.
21. A method of manufacturing a gas appliance according to any of claims 14 to 20, wherein a valve configured to allow a variable rate of gas flow is included within said flow control means.
22. A method of manufacturing a gas appliance according to any of claims 14 to 21, wherein an electromagnet is included within said flow control 12 means.
23. A method of manufacturing a gas appliance according to any of claims 14 to 22, including the steps of configuring a frame surround of said appliance to be mountable to a wall, and locating said cam within said frame surround.
24. A method of manufacturing a gas appliance according to any of claims 14 to 23, wherein said gas appliance is a fire.
25. A method of manufacturing a gas appliance according to any of claims 14 to 24, wherein said gas appliance is a fire and said fire is configured to be inset into a wall.
26. A method of manufacturing a gas appliance according to any of claims 14 to 24, wherein said cam is made from a plastics material.