GB2284651A

GB2284651A - A gas valve

Info

Publication number: GB2284651A
Application number: GB9423493A
Authority: GB
Inventors: Andre Alain Jean Moreau; Michel Jean Jack Lepron
Original assignee: Sourdillon SA
Current assignee: Sourdillon SA
Priority date: 1993-11-24
Filing date: 1994-11-21
Publication date: 1995-06-14
Anticipated expiration: 2014-11-21
Also published as: FR2712963B1; IT1269155B; ES2118024A1; FR2712963A1; GB9423493D0; ES2118024B1; ITFI940211A0; DE4441926A1; ITFI940211A1; GB2284651B

Description

2284651 PATENTS ACT 1977

DESCRIPTION OF INVENTION

INPROVEMENTS IN OR RELATING TO A GAS VALVE THIS INVENTION relates to improvements to gas valves and more particularly to gas valves with safety means for supplying gas to a gas burner. The invention especially relates to a gas valve for supplying gas to a gas burner in a domestic gas appliance of the flat type, comprising a gas inlet, a means for controlling the rate of f low of gas, such means being rotated by a control shaft which is also axially movable (first direction), said shaft extending downstream of the control means in a gas flow passage, a safety valve comprising an electromagnet powered by a thermocouple and disposed downstream of the control means, said safety valve having a valve member mounted on a setting rod axially movable (second direction) forming an angle with the said control shaft, a transmission system interposed between the control shaft and the setting rod of the safety valve member, arranged so that an axial movement of the control shaft produces an axial movement of the safety valve member and of the setting rod of the safety valve, and a gas outlet situated downstream of said saf ety valve member.

The construction of domestic gas appliances of the flat or extra-f lat type (for example hobs equipped with at least one gas burner) gives rise to considerable problems in respect of accommodating the components. With regard more particularly to gas supply valves intended to control the respective burners, the conventional practice is f or the gas f low control knobs to be situated on the top of the hob, with the supply valves being disposed vertically beneath the hob. However, the assembly height provided for such hobs is too small to enable certain auxiliary components, e.g. manually set thermocouple-powered safety valves, to be accommodated in alignment with the axes of the valves.

It is for this reason that in this type of appliance provision has been made to accommodate the safety valves, not in alignment with the axes of the gas supply valves, but on the side thereof, e.g. approximately perpendicularly thereto. Transmission of the control movement, initiated by an axial displacement of the gas f low control valve actuating shaft, is provided by angular transmission mechanisms using key and cam systems (for example see FR-A2 565 667 and GB-A-2 196 732) or expansible means systems (see, for example, FR-A-2 659 130).

As a result, the movement transmission mechanisms used to date, irrespective of their construction, are relatively bulky and complicated to install, let alone manufacture and adjust, and because of the friction exerted between the moving components, and the risk of jamming, their operation may be unreliable, resulting in a relatively short lif e. In particular, the relative bulk of these known transmission mechanisms makes them unsuitable f or use in gas valves incorporating a saf ety valve and having a low height intended for hobs.

The present invention seeks to provide an improved gas supply valve.

According to this invention there is provided a gas valve with saf ety means to control the supply of gas to a gas burner, comprising: a gas inlet (3), a means (4) for controlling the rate of f low of gas, such means being rotatable by a control shaft (6) which is also axially movable (first direction), a saf ety valve (11) comprising an electromagnet powered by a thermocouple and disposed downstream of the control means (4), said safety valve having a valve member (12) mounted on a setting rod (12a) axially movable (second direction) forming an angle with the said control shaft, a transmission system (16) interposed between the control shaft (6) and the setting rod (12a) of the saf ety valve member, arranged so that an axial movement of the control shaft produces an axial movement of the safety valve member (12) and of the setting rod (12a) of the safety valve (11), and a gas outlet (15) situated downstream of said safety valve member (12), wherein the movement transmission is accommodated in a recess (28) situated beside the control means (4) and one side wall of which has an aperture (14) for the passage of the gas in the direction of the safety valve (11), and and wherein the movement transmission (16) comprises:

a pivoting setting lever (17) mounted for free rotation in the recess (28) and defining a contact surface (20) situated adjacent said valve member (12) of the saf ety valve (1) so that rotation of the setting lever results in a movement of the contact surface which, on coming into contact with the saf ety valve member, moves the latter in the opening direction, resilient return means (22; 12b) arranged so that in the absence of a f orce applied to the setting lever the latter is returned to its position of rest in which the safety valve member (12) is in the closed position, and a drive lever (25) interposed between the setting lever (17) and the free end (6a) of the control shaft (6) so that an axial movement of said control shaft is accompanied by pivoting of the setting lever.

Constructed in this way, the transmission mechanism comprises no parts which rub against each other or any parts liable to wear. It comprises only two parts articulated for rotation - the setting lever mounted for rotation on the valve body and one end of the drive lever mounted for rotation on the setting lever - and the relative position of the various parts does not have to be very accurate: some of the arrangements referred to hereinafter may also allow clearances and mutual offsets to be dispensed with. A system of this kind can therefore provide reliability for a very high number of operations.

Advantageously, to obtain a compact assembly, the safety valve member is arranged selectively to close the said gas passage aperture through the wall of the recess and the contact surface is f ormed by a free end of said setting lever situated approximately opposite said aperture. In one preferred embodiment, the setting lever is in the general form of a U on its side mounted for free rotation at or near the end of its top arm, on which the drive lever is fixed in the zone of the bottom of the U, and the end of the bottom arm of which constitutes the said contact surface. The transmission mechanism then comprises a relatively small number of components.

Advantageously, to minimise friction within the mechanism to the maximum, the drive lever is mounted for free rotation on the setting lever; also, advantageously, the end of the drive lever co-operating with the free end of the control shaft is flattened to form a platform disposed opposite the said free end of the control shaft and extending transversely thereof.

It is also advantageous if a clearance is provided between the cooperating ends of the control shaft and of the drive lever and/or between the contact surface moved by the setting lever and the safety valve member so that setting of the safety valve member is obtained only at the end of the axial travel of the control shaft; an arrangement of this kind permits offsets between the control shaft and the drive lever and obviates the need for close assembly tolerances for the components.

With the above means it is possible to construct a gas valve arrangement with safety means in which the control shaft and the setting rod have respective axes approximately perpendicularly to one another and noncoplanar. All the constituent parts of the movement transmission are then disposed laterally of the rotating member of the gas valve and only the end platform of the drive lever is situated in extension of the control shaft. In these conditions, a very compact valve is obtained and, despite the presence of the movement transmission mechanism, the valve body retains approximately the same height (the dimension measured parallel to the control shaft) as a conventional valve body without safety means. A preferred valve according to the invention can therefore be used for a cooking appliance, such as a hob, in which the space available beneath the hob is very small, and it may in such cases even replace existing conventional valves.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated the invention will now be described by way of example with reference to the accompanying drawings in which:

FIGURE 1 is a side view of a gas supply system for a gas burner in accordance with the invention in a first position, and FIGURE 2 is a view corresponding to Figure 1 showing the system in another position.

Referring firstly to Fig. 1, a gas supply valve 1 comprises a solid body 2 having a gas inlet aperture (not visible in the drawing because it is situated in the sectioned part denoted by the broken-line arrow 3) horizontally communicating with a conical rotating valve member 4, having a vertical axis, for controlling the gas flow. The valve is provided with a vertical actuating shaft 5, the top free end of which is adapted to receive an actuating knob (not shown). At its opposite end, the actuating shaft 5 is provided with a projecting radial pin 7 engaging in a vertical groove 4a in the valve member 4 so as to create a rotary coupling between the shaft and the valve member while leaving the shaft 5 free to move axially with respect to the valve member 4.

Also, although barely visible in Fig. 1, the pin 7 is extended beyond the slot 4a so that its free end engages in a groove 2b formed in the inner surface of a cap 2a surmounting the valve member 4 and integral with the body 2. The groove 2b has a vertical rectilinear portion which is visible in Fig. 1, and a circular portion extending transversely with respect to the shaft 5 and connected to the rectilinear portion towards the bottom thereof.

A second shaft or transmission shaft 6 extends beneath the shaft 5 and in axial alignment therewith and is permanently urged against the bottom end of the actuating shaft 5 by a spring 8. Thus the axial movement of the actuating shaft 5 produces an identical movement of the transmission shaft 6 while the latter remains free with respect to rotary movements of the actuating shaft 5; conversely, the return spring 8, by acting on the transmission shaft 6, also returns the actuating shaft 5 to the initial axial position.

Although the shafts 5 and 6 are structurally separate to facilitate production and assembly of the parts, they are functionally joined in respect of their axial movements, which are more specifically considered below. Hereinafter these two shafts will therefore be designated generally by the unitary name: flow-control valve control shaft 6.

The bottom part of the shaft 6 extends axially through an axial cavity 4b in the valve member 4, which at the bottom end of the latter opens into a chamber 9 def ined at the base of the body 2. The bottom end 6a of the shaft, in the position of rest shown in Fig. 1, is situated approximately level with the bottom end of the valve member 4. A section of conduit 10 containing a safety valve 11 having an electromagnet powered by a thermocouple (not shown) extends, more particularly at a right angle with respect to the shaft 6, from a lateral recess (to be described hereinafter) communicating with the chamber 9. The member 12 of the safety valve bears sealingly, by the action of a spring 12b, against an annular seat 13 surrounding an orifice 14 providing communication between the chamber 9 and the section of conduit 10. The valve member 12 is carried at the end of an axially movable rod 12a which forms the core of the electromagnet or is integral with said core.

Downstream of the valve member 12 the conduit section 10 is connected to an outlet orifice 15 for the gas intended for the gas burner (not shown) controlled by the valve 1.

Operation of the system described above is as follows. With the valve closed, the valve member 12 of the safety valve is kept applied to its seat by its spring 12b. To operate the burner, pressure is applied axially to the flow-control valve shaft 6. This axial movement is transmitted by a transmission system 16 (to be described in detail hereinafter) to the rod 12a of the safety valve 11 so that said rod is moved in the direction to open the valve member 12 (to the left in Fig. 1). The shaft 6 having simultaneously turned to bring the valve member 4 into the open position, the gas f lows through the open saf ety valve 11 to the burner, where it is ignited. The said thermocouple then produces an electric current which is applied to the electromagnet of the saf ety valve 11. The electromagnet thus energised holds the rod 12a in the position that it occupies with the valve member 12 in the open position. As soon as the electromagnet is energised, the shaft 6 can be released and is urged back by the spring 8 to retain its angular position controlling the required opening of the valve member 4.

As soon as the burner is extinguished, and more particularly if the flames are accidentally blown out, the electromagnet is no longer energised and, since the rod 12a is no longer held, the spring 12b returns the valve member 12 to its seat 13 to interrupt the flow of gas.

The transmission system 16 is accommodated in a recess 28 defined in the body 2 laterally of the valve member 4. The control shaft 6 and the saf ety valve 11 are so disposed that their respective axes are substantially perpendicular to one another but not coplanar and are separated from one another so that the transmission system 16 is interposed, not only functionally, but also physically, between the valve member 12 and the control shaft 6. In practice, the recess 28 accommodating the transmission system 16 and the chamber 9 beneath the valve member 4 comprise just one and the same free volume of complex shape def ined within the body 1.

The transmission system 16 comprises a setting lever 17 which, in the example illustrated, has the general shape of a U on its side. The setting lever 17 is pivotally mounted for free rotation on the wall of the recess 28 by means of a shaft or pivot 18 situated at the free end of the top arm 19 of the setting lever. The free end 20 of the other arm 21 of the U-lever acts as a support or a plunger adapted to co-operate with the valve member 12 or, in this case, the end of the rod 12a supporting the valve member 12.

Return of the setting lever 17 to the position of rest (as shown in Figure 1)is provided by a spring 22. For example, the spring 22 may be a helical torsion spring located on a support pin 23 integral with the U- lever and coaxial with the pivot 18, the two ends bearing respectively against the wall of the recess 28 and against a stop 24 integral with the U-lever 17.

A drive lever 25 is interposed between the setting lever 17 and the control shaft 6 to transmit the movement of the latter to the setting lever. The drive lever comprises a wire rod, of which the top end 26, bent through approximately 900 is supported for free rotation by the Ulever 17 and extends substantially perpendicularly to the latter. For example, the top bent end 2 6 forming the rotary pivot is received in a tapped hole f ormed through the lever 17 in the said projecting stop 24 as shown in Fig. 1. The opposite end of the drive lever 25 is bent through approximately 900 in the opposite direction to the top end 26 to extend as far as the bottom end of the valve member 4 facing the free end 6a of the shaft 6; this end of the drive lever 25 is flattened to form a platform 27 extending substantially transversely in relation to the shaft 6 and facilitating the contact with the end 6a of the shaft 6.

During axial pushing-in of the control shaft 6, its end 6a comes into contact with the platform 26 and, in pushing it down, drives the lever 25 which in turn drives the setting lever 17 so that it rotates about its pivot 18; its free end 20 abuts against the safety valve member 12 or the end of the rod 12a supporting the latter and moves the valve member 12 away from its seat 13 so that the gas can reach the outlet orifice 14.

When the shaft 6 resumes its position of rest, the setting lever 17 is returned by the spring 22 while the valve member 12 is returned to the closure position by the spring 12b.

Clearance is provided between the co-operating ends of the control shaft and of the drive lever andlor between the contact surface moved by the setting lever and the valve member so that setting of the safety valve is obtained only at the end of the axial travel of the control shaft.

In a variant, the spring 22 specifically associated with returning the setting lever 17 could be dispensed with; in that case the lever 17 would remain free and its end 20 would rest by gravity against the valve member 12, but without being able to open said valve member in the absence of a driving force generated by the shaft 6; on closure, the spring 12b would push the valve 12 back against its seat and drive back the lever 17.

It will readily be seen that the above-described mechanism operates without appreciable friction and that its presence does not appreciably increase the force required to be exerted axially on the shaft 6 to operate the associated burner. The presence of this mechanism cannot, therefore, interfere with operation of the gas supply valve by a user.

Also, the mechanism can be so arranged that -4n the position of rest the platform 27 is positioned a very short distance from the bottom end of the valve member, allowing for production and assembly tolerances. As a result, the height of the chamber 9 is in direct relationship to the amplitude of the axial travel of the control shaft 6. The gas valve can thus have a height which does not appreciably exceed the height of a conventional gas valve (for example it may be exceed it just by 1 or 1.5 nz or even less). The vertical space occupied by the gas valve described above is substantially the same as that of the prior art valves and, despite the presence of the safety valve and its actuating mechanism with an angular movement transmission, it can be mounted on hobs without any restrictive conditions.

From the foregoing it will be appreciated that the preferred embodiment of the invention provides a linear movement angular transmission for gas supply valves which as far as possible obviates the disadvantages of the equivalent mechanisms used heretofore, and which in particular is of simple structure with a minimum of which rub against each other parts in order to reduce resistance and wear, the system being easy to manufacture with simple tools, easy to fit, and requiring no adjustments or maintenance; also, and in particular, the preferred embodiment comprises an arrangement which is not bulky and which makes it possible to construct gas valves with a safety valve having the smallest possible height, especially for the purpose of equipping hobs.

Claims

C L A I M S

1. A gas valve with safety means to control the supply of gas to a gas burner, comprising: a gas inlet (3), a means (4) for controlling the rate of f low of gas, such means being rotatable by a control shaft (6) which is also axially movable (first direction), a saf ety valve (11) comprising an electromagnet powered by a thermocouple and disposed downstream of the control means (4), said safety valve having a valve member (12) mounted on a setting rod (12a) axially movable (second direction) forming an angle with the said control shaft, a transmission system (16) interposed between the control shaft (6) and the setting rod (12a) of the safety valve member, arranged so that an axial movement of the control shaft produces an axial movement of the saf ety valve member (12) and of the setting rod (12a) of the safety valve (11), and a gas outlet (15) situated downstream of said safety valve member (12), wherein the movement transmission is accommodated in a recess (28) situated beside the control means (4) and one side wall of which has an aperture (14) for the passage of the gas in the direction of the safety valve (11), and and wherein the movement transmission (16) comprises:

a pivoting setting lever (17) mounted for free rotation in the recess (28) and defining a contact surface (20) situated adjacent said valve member (12) of the saf ety valve (1) so that rotation of the setting lever results in a movement of the contact surface which, on coming into contact with the saf ety valve member, moves the latter in the opening direction, resilient return means (22; 12b) arranged so that in the absence of a force applied to the setting lever the latter is returned to its position of rest in which the safety valve member (12) is in the closed position, and a drive lever (25) interposed between the setting lever (17) and the free end (6a) of the control shaft (6) so that an axial movement of said control shaft is accompanied by pivoting of the setting lever.

2. A gas valve according to claim 1, characterised in that the safety valve member (12) is arranged selectively to close the said gas passage aperture (14) through the wall of the recess (28) and in that the contact surface (20) is formed by a free end of said setting lever (17) situated approximately opposite said aperture (14).

3. A gas valve according to claim 2, characterised in that the setting lever (17) is in the general form of a U on its side mounted for free rotation at or near one end of its top arm (19), on which the drive lever (25) is fixed in the zone of the bottom of the U, and the end of the bottom arm (21) of which constitutes the said contact surface (20).

4. A gas valve according to any one of claims 1 to 3, characterised in that the drive lever (25) is mounted for free rotation on the setting lever (17).

5. A gas valve according to any one of claims 1 to 4, characterised in that the end (27) of the drive lever (25) co-operating with the free end (6a) of the control shaft (6) is flattened to form a platform disposed opposite the said free end of the control shaft and extending transversely thereof.

6. A gas valve according to any one of claims 1 to 5, characterised in that the setting lever return means comprise a spring (22), more particularly a torsion spring coaxial with the pivot axis (18) of the setting lever (17).

7. A gas valve according to any one of claims 1 to 5, characterised in that the return means comprise a spring (12b) for returning the safety valve member (12) to the closure position.

8. A gas valve according to any one of claims 1 to 7, characterised in that a clearance is provided between the co-operating ends of the control shaft and of the drive lever andlor between the contact surface moved by the setting lever and the safety valve member so that setting of the safety valve member is obtained only at the end of the axial travel of the control shaft.

9. A gas valve according to any one of claims 1 to 8, characterised in that the control shaft (6) and the setting rod (12a) have respective axes approximately perpendicular to one another and non-coplanar.

10. A gas valve substantially as herein described, with reference to and a shown in the accompanying drawings.

11. Any novel feature or combination of features disclosed herein.