FR2481417A1 - Piezoelectric ignition switch for gas appliance - has hammer raised by cam surfaces as gas tap control is turned on - Google Patents

Abstract

The control and piezoelectric igniter for a gas appliance includes a body formed of moulded plastic (1) with a square section container (3) for a piezoelectric element (4). The rotary control (18) is connected via a shaft (17) to the valve (31) controlling the flow of gas. Parallel to this shaft there is an intermediate shaft (7) carrying two cams (8,9), a spring holding this shaft in one of its extreme positions. A further shaft parallel to these two shafts provides a pivoting support for the hammer (13) which is spring biased towards the piezoelectric element. Of the two cams (8,9) one is engaged by a projecting rib (16) on the control shaft and the other engages a part of the hammer support (19) so that the rotation of the control knob is transmitted to lift the hammer back so that it may strike the piezoelement.

Description

Piezoelectric qaz ignition device for household appliances such as gas stoves, stoves and the like.

The present invention relates to a piezoelectric gas ignition device for household appliances such as gas stoves, stoves and the like, of the type comprising a rotary control axis carrying at the end an operating button operable by the user and connected, for the control of the gas supply flow rate to a burner of the appliance in question, to the movable member or key of a control valve of the plug type or the like, interposed on the gas supply pipe, said axis control being further arranged to control during its rotation the triggering of a piezoelectric igniter for producing sparks whose edator is associated with said burner, and being axially movable against the action of 'a return spring and from a rest position in axial abutment, so that its rotation is authorized, at least for controlling the supply of gas to the burner, only after a preliminary operation consisting, for the user, to exercise an axial force on said operating button, in principle a pressing force, to cause it to leave said rest position in axial abutment
This type of device has the advantage of having a single operating member, which of course only requires manipulation with one hand, both for the control of the gas supply and the production of ignition sparks. and the regulation of the gas flow, instead, like other devices, of presenting an independent actuating member of the piezoelectric igniter, which then requires, when switching on, a manipulation with two hands.

 The single control devices concerned by the invention therefore represent progress, but the devices currently known are not free from operating difficulties.

 This can happen in particular for household appliances connected to the gas source - distribution network or cylinder - by a pipe which can sometimes be quite long.

 In fact, the safety instructions recommend that, when the household appliance is not in use for a relatively long period, the shut-off valve located at the point of connection of the pipe to said source, the porosity of the pipe and the small leaks at the fittings and joints mean that it gradually empties the gas it contains even when the taps of the household appliance are also closed, which causes a relatively large volume of air to appear in this pipe.

 The presence of this volume of buffer air prevents considering the implementation of a device arranged so that the spark of the igniter occurs from the opening of the tap of the household appliance. Indeed, with such a device, the spark would frequently occur before the gas arrives at the burner, while the evacuation of the volume of buffer air is not yet complete, and the gas could not be ignited that after other attempts, this requires a return of the valve to its closed starting position and the unpleasant repetition of the complete ignition maneuver.

 As for foreseeing, by the very design of the device, the creation of a constant delay time between the opening of the tap of the device and the production of the spark, this also does not make it possible to resolve the problem in a manner satisfactory, since the spark could still occur either too early or too late, compared to the time of the arrival of the gas at the burner. In fact, the exact delay to be expected cannot be determined in advance and once and for all with sufficient precision, since the desirable delay is essentially dependent on installation-specific parameters, such as length of the pipe, importance of the porosity and leaks at fittings and seals, manufacturing tolerances for mechanical components, injector diameters, gas flow characteristics in the appliance's piping, etc.

 The object of the present invention is to remedy all these drawbacks of known devices, and to develop a device of the type in question which makes it possible to obtain ignition without fail, on the first attempt.

To this end, a device of the general type defined at the start is, in accordance with the invention, characterized in that it is further arranged so that, after said preliminary operation has been carried out, a first rotational movement, imposed on said rotary control axis by means of an additional action in rotation exerted by the user on the operating button, produces an arming of the hammer of said piezoelectric igniter, and so that, just before the triggering of the igniter and while the tap is at full opening or approximately at full opening, said rotation action of the user is momentarily stopped by the abutment of a lug or the like of the axis on a stopper , the triggering of the igniter and the continuation of the rotational movement, for the adjustment of the gas flow rate, which cannot then be sgeffeeeue-, with a time delay freely determined and at this instant by the user, that after release of the axial force exerted on the operating button, allowing said lug to cross the stop
We see that such a device is designed so that it leaves it to the user to determine, based on the experience acquired, the delay time between the full opening of the tap 1 household appliance concerns , and the production of the spark by the piezoelectric igniter is the stopping time observed by the user, when the lug or the like of the rotary control axis has arrived at the stop on the stop, before it triggers the igniter by releasing the axial pressure (or traction) exerted on the operating button, then continuing its rotation The concept and almost instinctive measurement of this necessary stopping time, depending on characteristics specific to the installation and only the beginning of which will be determined immutably by the structure of the mechanism, will be acquired very quickly and effortlessly, and a minimum of habit will thus allow the user, without special address, to blow ignition safe and at the first attempt
In short, the present invention therefore consists in making a device which allows the user to dissociate over time the opening of the tap and the production of the ignition spark, with however still a single control axis and a single operating button, without compromising the principles of valve construction and their standards, nor their safety.

 A device according to the invention may include many other advantageous constructive characteristics, which will be indicated in due course in the following.

An embodiment of the invention will now be described by way of non-limiting example, with reference to the figures of the accompanying drawing in which
- Figure 1 is an exploded general view of an ignition device according to the invention as well as the tap of a gas household appliance, the position of the different parts being that which is reached at the instant immediately preceding piezoelectric igniter tripping
- Figures 2 to 4 are cross-sectional views of the device along different planes perpendicular to the rotary control axis;

- Figures 5 to 7 are cross-sectional views of the tap of the household appliance, in different operating positions (Figure 5: closed position; Figure 6 almost full opening position, when sparks are produced; Figure 7: full opening position), and
FIG. 8 represents a light plate cooperating with a finger of the rotary axis, in a position corresponding to that of the tap in FIG. 7.

In the figures where it is visible, the body of the piezoelectric igniter, for example made of plastic molded in one piece, has been referenced at 1. In FIG. 1, it has been shown cut along edges 2 of the housing 3 of the piezoelectric element 4 only for clarity of the drawing. In fact, this housing 3 is closed without discontinuity by the flange 5, which is an integral part. Between this flange 5 and another flange 6, which faces it, of said igniter body 1, are mounted
- an intermediate axis 7 carrying two intermediate cams
diaries 8 and 9 integral with the same sleeve 10 in
spun on axis 7, these two cams being recalled
in the position shown in Figure 3 by a
helical spring with rotational stress, in
steel wire 11 (springs of this type do not have
shown in Figure 1, also for the
clarity of the drawing)
- an axis 12 for pivoting the hammer 13 of the al
light, also recalled in the position shown
tée in Figures 2 and 3 by a helical spring of
same type as the previous one, referenced in 14, and
- a sleeve 15 with control cam 16 suitable for cooperating
rer with the intermediate cam 8, this sleeve being
threaded and wedged on a rotary control axis 17,
hollow and flat, bearing at its free end,
externally with respect to the flange 5, a button
conventional maneuvering 18.

 As can be seen in the figures, the arrangement of the different parts between them is also such that, for its part, the other intermediate cam 9 of the sleeve 10 can cooperate with a heel 19 of the pivot arm 20 of the hammer 13 of the igniter.

 Of course, the flanges 5 and 6 have holes forming bearings, for carrying the ends of the different axes of the mechanism.

Externally, the flange 5 of the body 1 of the igniter carries
- an arched guide 21 behind which can come engaged
manage a lug 22 carried by a ring 23 wedged in ro
axially, thanks to a clamping screw 24,
on the control axis 17
a stop pad 25, capable of blocking rotation,
clockwise from a swivel ring 26 threaded
tied on the protruding end of the intermediate axis
7 and carrying a radial projection forming a retainer 27
able to cooperate with the aforementioned lug 22; and
- a helical return spring 28, of the same type as
the previous ones, whose fixed end is stopped
by a stop 29, this spring urging the ring
supra 26 clockwise.

 The other end of the rotary control axis 17 is connected to the key 30 of the gas tap 31 of the stove or similar gas household appliance, this tap being of a plug type or of the same kind, well known. The key 30, which is axially hollow, also comprises, in a conventional manner, two nozzles 32 and 33 for the main gas passage, enabling the inlet connector 34, connected to the gas source, to be placed in communication with the outlet connector. 35, connected by a supply line 36 to the burner 37 of the stove; this key is also crossed by a finer pilot light nozzle, 38. The spark gap associated with the burner 37 is referenced at 39 and connected by a wire 40 to the output terminal 41 of the piezoelectric igniter 4 .

 For the ground connection, it is possible to use a ground lug 42 provided on a folded sheet metal support 43 (FIG. 4). This support, which constitutes the intermediate piece allowing the body 1 to be fixed to the tap, and positioned with respect to it, in cooperation with the rotary control axis 17 which carries the flanges 4 and 5, is fixed by screws 44 on the valve body 31 (corresponding holes in the valve body referenced at 45), it carries an arcuate opening 46 which receives a screw 47 (FIG. 2), which passes through a spacer 48 connecting the flanges 5 and 6 of the device. , like the housing 3, is an integral part of the flanges 5 and 6, contrary to what might appear on examining FIG. in which, for the sake of clarity as already specified above, the flange 5 has been shown as torn from the rest of the device. Thanks to this screw 47, which carries a nut (not shown) tightened behind the metal support 43, and which, before tightening the nut, can move in the arcuate opening 46, the angular positioning of the assembly can be adjusted molded from the body l of the igniter and all of its members with respect to the tap 31. At the same time an axial setting of this body 1 is obtained with respect to the tap.

 Between the metal support 43 and the valve body 31 is interposed a metal light plate 49 (Figures 1, 4 and 8) carrying a spacer barrel 50 threaded on the control axis 17. This plate is fixed to the valve body by the same screws 44 which are used for fixing the support 43 (holes 51 of the plate), it carries two arcuate lights 52 and 53 whose role will be seen later and in which a finger 54 d can engage selectively 'a flange 55 secured to the control pin 17.

 Finally, a helical return spring 56 is compressed between the valve body 31 and the flange 55. This spring therefore tends constantly to push the control axis 17 to the right of FIG. 1, in order to tend to bring this axis towards this which has been called above its "rest position in axial stop".

 That said, the operation of the device which has just been described is as follows.

 It is assumed that initially the gas is closed and that the various organs of the device are in the position shown in FIGS. 2 to 5.

In this position, it is not possible to turn the operating button 18, and therefore to open the valve 31, without first exerting a push on this button, against the restoring force exerted by the spring. 56, to cause the axis to leave said rest position in axial abutment. Indeed, the user is then prevented on the one hand by blocking the finger 54 of the flange 55 in the small lumen 52 of the plate 49 (see Figure 4), and on the other hand by the additional abutment of the lug 22 of the ring 23 at 1 entry of the arched guide 21 (see Figure 2)
On the other hand, after having exerted this axial thrust on the button f8, e one can turn it in the normal anti-clockwise direction, because then the finger 54 can be released from the light 52 and the lug 22 pass in the arched guide 21 It should be noted that, then, the axial pressure can be released because the axis 17 is maintained in its depressed position, owing to the fact that the guide 21 then axially retains the lug 22 of the ring 23 fixed on the axis.

The rotation of the operating button 18 and therefore of the axis 17 then causes, at the same time as the rotation of the key 30 of the tap 31, e, some time after, the progressive opening of the latter, the rotation of the sleeve. 15. The control cam 16 actuates the intermediate cam 8, the sleeve 10 rotates clockwise on the intermediate axis 7, and the other intermediate cam 9 actuates the heel 19 of the pivot arm 20 of the hammer 13 of the This arm then turns counterclockwise, against the return force of the spring 14, which produces the arming of the hammer
When the hammer 13 is fully armed (FIG. 1), the lug 22 comes into abutment on the retainer 27 of the ring 26, which cannot rotate clockwise due to its abutment on the stud 25.

 It is at this moment that the user observes a downtime, determined by his experience, before continuing the ignition maneuver. When this time seems sufficient to him (it can be a fraction of a second or more), he just has to let the button 18 come back towards him, that is to say to let the axis 17 slide axially relative to the body 1 of the device and at the tap, under the action of the return spring 56. The finger 54 of the flange 55 which, during the first phase of rotation, slid against the rear face of the light plate 49 and therefore cooperated indirectly with the the lug 22 for axially blocking the axis 17, then authorizes this axial return of the axis, by penetrating into the arched lumen 53, at the same time as the lug 22 escapes from the arched guide 21.

 In this way, from the start of the next phase of rotation of the button 18 in the counterclockwise direction, the ignition is obtained, the hammer 13 falling suddenly on the piezoelectric element, under the effect of its spring 14, which was bandaged during the previous rotation phase.

 This release of the hammer 13 is authorized at the instant in question because the intermediate cam 8 then escapes the retaining action of the control cam 16 and allows the sleeve 10 to pivot counterclockwise, under the action of the heel 19, and, as a result of the consecutive erasure of the other intermediate cam 9, the pivoting of the lever 20 clockwise.

 The key 30 of the tap 31 then occupies the position close to the maximum opening, which is shown in FIG. 6.

 By continuing to turn the button 18 counterclockwise, the gas can then be adjusted in the usual way, the finger 54 of the collar 55 then being free to move in the arcuate lumen 53 (FIG. 8), the gas flow beginning to decrease when one exceeds, in a counterclockwise direction, the position of FIG. 7 and this, if necessary, up to a pilot position for which it is the nozzle 38 which, instead of the nozzle 32, communicates with input 34.

 To close the tap, the button 18 is turned clockwise, until the finger 54 comes up against the left edge of the arched light 53, then simply push the button 18 to continue the movement, and allow for this finger to come out of the light, and for the lug 22 to re-enter behind the arched guide 21, until the tap is closed, and, after releasing the button, the penetration of the finger 54 into the small light 52, which returns to the starting position.

 If one exerts on the operating button 18 the axial pressing pressure before the lug 22 passes the stopper 27, this is of no consequence because the stopper constitutes a stop in only one direction. The lug 22 will in fact cause the stopper to be erased, by then rotating the ring 26 counterclockwise, against the force of its return spring 28.

 It should be noted that any attempt to relight is thus subject to a return to this starting position, corresponding to the complete closing of the valve, which further improves safety.

 As is obvious, and as already follows from the foregoing, the invention is in no way limited to those of its modes of application and embodiments which have been more especially envisaged; on the contrary, it embraces all its variants.

 In particular, it would of course be possible to replace each member with a member capable of performing an equivalent function, and for example the ring 26 to be stopped 27 by a ramp device or the like.

Claims (8)

 1. Piezoelectric gas ignition device for household appliances such as gas stoves, stoves and the like, of the type comprising a rotary control axis carrying at the end an operating button operable by the user and connected, for control of the gas supply flow rate to a burner of the appliance in question, to the movable member or key of a plug-type control valve or the like, interposed on the gas supply pipe, said axis of control being further arranged to control during its rotation the triggering of a piezoelectric igniter for producing sparks whose spark gap is associated with said burner, and being axially movable against the action of a spring return and from a rest position in axial abutment, so that its rotation is authorized, at least for controlling the supply of gas to the burner, only after a preliminary operation consisting, for the user , to exert an axial force on said end it is maneuvering, in principle a pressing force, to make it leave said rest position - in axial stop, device characterized in that it is further arranged so that, after said preliminary operation has been carried out, a first movement of rotation, imposed on said rotary control axis (17) by means of an additional action in rotation exerted by the user on the operating button (18) produces an arming of the hammer (13) of said piezoelectric igniter (4), and so that, just before the triggering of the igniter can take place and while the tap (31) is at full opening or approximately at full opening, said action in rotation of the user is momentarily stopped by a stop of a lug or the like (22) of the axis on a retainer (27), the triggering of the igniter and the continuation of the rotational movement, for adjusting the gas flow rate, does not which can then be carried out, with a te mporisation determined freely and at this time by the user, only after the axial force exerted on the operating button has been released, allowing said lug (22) to pass the stop (27).  2. Device according to claim 1, characterized in that on said rotary control axis (17) is threaded a helical spring (56) compressed between the valve body (31) and a flange (55) integral with the axis, this to generate the return force of the axis (17) to its rest position in axial stop.  3. Device according to claim 1 or 2, characterized in that in its rest position in axial stop, the rotary control axis (17) is locked in rotation by the engagement of a finger (54) of the flange (55) in a light (52) of a light plate (49) threaded on the axis.  4. Device according to any one of the preceding claims, characterized in that in its rest position in axial abutment, one rotary control axis (17) is locked in rotation by the abutment of a lug (22) on the tree of an arched guide (21 ;.  5 Device according to any one of the preceding claims, characterized in that the various members of the hammer arming and releasing mechanism (13) of the piezoelectric element (4) are carried in an igniter body ( 1) made of plastic, comprising, in an integrated manner, the housing (3) of the element, and engaged, by means of two end flanges (5, 6), on said rotary control axis (17 )  6. Device according to any one of the preceding claims, characterized in that the hammer arm mechanism (13) of the piezoelectric element comprises an intermediate axis (7) carrying two intermediate cams (8,9 ) one of which (8) is adapted to cooperate with a cam: control (16) of a sleeve (15) wedged on the rotary control axis (17), and the other (9) is suitable for cooperate with a heel (19) of a pivot arm (20) of said hammer.  7. Device according to claims 5 and 6, characterized in that the intermediate axis (7) and the pivot axis (12) of the hammer are carried, at their ends, by holes in the flanges (5,6).  8. Device according to any one of the preceding claims, characterized in that it comprises a support (43) fixed on the valve body (31) and carrying an arcuate opening (46) for angular positioning of the igniter body  (1) and all of its organs, with respect to said valve body.  9. Device according to any one of the preceding claims, characterized in that said retainer (27) consists of a radial projection of a pivoting ring  (26), said projection being able to block the passage of the lug or the like (22) of the axis in a direction of rotation, and to fade in front of this lug in the other direction.  10. Device according to any one of claims 3 to 9, characterized in that said light plate  (49) comprises an arcuate light (53) in which said finger (54) of the collar (55) can move when the operating button (18) is actuated for --- adjusting the flow rate gas.  11. Device according to claim 9 or 10, characterized in that the intermediate axis (7), the pivot axis  (12) of the hammer, and the pivoting ring (26) are rotated by return springs.