EP0172973B1 - Piezoelectric igniter mechanism - Google Patents

Description

The present invention relates to a piezoelectric ignition mechanism, in particular for a gas lighter, of the type comprising a female body of cylindrical bore in which is engaged a sheath of complementary external section containing, in order, from its outer end, a metal anvil serving as an electrode, a piezoelectric element and a metal stopper, while between the bottom of the female body and the inner end of the sheath are arranged two concentric helical springs, one outside of return of the sheath and bearing against the internal end of the latter, and the other detent interior bearing on a striker provided with two diametrically opposite lugs, each of which is engaged, on the one hand, in a window made in the adjacent wall of the female body, and, on the other hand, in a longitudinal guide slot formed in the sheath, opening at its internal end and each of which has a notch, one of which edge constitutes a notch for the attachment of the corresponding lug in which it is normally pushed by the action of a ramp formed in the transverse edge of the associated window furthest from the bottom of the female body and against which it is normally applied by the detent spring, notch from which it is ejected by application against a ramp, inclined in the same direction but of opposite effect, formed in the opposite edge of the aforementioned window and against which it is applied during the operation of the mechanism , in the direction corresponding to an increase in the relative engagement of the sheath and the female body and to compression of the two springs.

FR-A-2 072 425 shows a mechanism of this type in which the cross section of the cylindrical bore of the female body and of the external perimeter of the sheath is circular, which implies mounting of the pins after engagement of the striker in the sheath and in the female body, with the beginning of compression of the helical springs for returning the sheath and for relaxing the striker. For this reason, the pins are constituted by a pin engaged in a hole provided, for this purpose, radially in the striker, which considerably increases the cost price of the striker and that of the mounting of the mechanism.

From FR-A-2 498 740, another mechanism of this type is known, in which the pins of the striker are constituted by two radial projections of the latter, their engagement in the windows of the sheath being authorized by longitudinal slots formed in the latter er connecting, therefore, each of the windows at one end of the sheath. This device has the drawback, on the one hand, of imposing a rotation of the striker when the lugs reach the level of the windows to ensure their engagement in the latter and, on the other hand, of weakening the forrreau since one transverse edges of each of its windows is connected to it only by one side, like a gallows.

The present invention aims to remedy these drawbacks. To this end, in the mechanism which it concerns and which is of the aforementioned type, on the one hand the cross section of the bore of the female body and that of the sleeve have a non-circular perimeter, so as to have a larger dimension in a direction which does not pass through the windows of the female body than in the other directions, and, on the other hand, the distance separating the free ends of the diametrically opposite lugs of the striker is less than the greatest aforementioned dimension of the cross section of the female body and sheath but greater than the distance separating the two windows from the female body.

Thus, the pins can be obtained directly from molding with the striker which can be engaged in the female body, after the two helical springs, with its pins oriented in the direction of the largest dimension of the bore of the female body and be pivoted in a direction perpendicular to the planes of the windows, when the pins are at the level of the windows.

The engagement of the striker in the female body can be carried out quite simply by pushing it with the interior end of the sheath, so that after the pivoting of the striker at the level of the windows, the longitudinal slots of the sheath can engage on the pins of the striker and thus achieve the locking of the mechanism as a result of the engagement, immediately after, of each pin in the notch of the associated slot.

According to a simple embodiment of the invention, the cross section of the bore of the female body and that complementary to the sheath have the shape of a double warhead.

So that the rotation of the striker, from its position of engagement in the female body with its lugs oriented in the direction of the largest dimension of the bore of this body, to its normal position with its lugs engaged in the longitudinal windows of the female body and in the longitudinal slots of the sheath, is obtained automatically as soon as the pins are at the windows of the female body, according to an advantageous characteristic of the invention, the inner end of the latter has, on its edge and in the vicinity outlet of each longitudinal slot, on the side of the large dimension of its cross section, a ramp oriented so that, being applied against the corresponding lug, it tends to rotate the striker in the desired direction.

• Figure 1 en est une vue de côté en élévation;
• Figure 2 en est une vue en coupe suivant 2-2 de figure 1;
• Figure 3 en est une vue en coupe transversale suivant 3-3 de figure 2;
• Figure 4 est une vue partielle en perspective de l'extrémité intérieure du fourreau de ce mécanisme;
• Figure 5 est une vue similaire à figure 1 montrant le mécanisme en cours d'actionnement;
• Figure 6 est une vue similaire à figure 3 montrant la position du percuteur lors du montage du mécanisme;
• Figure 7 est une vue en coupe transversale illustrant le mode de montage de ce mécanisme.

In any case, the invention will be clearly understood with the aid of the description which follows, with reference to the appended schematic drawing representing, by way of nonlimiting example, an embodiment of this mechanism:

• Figure 1 is a side view in elevation;
• Figure 2 is a sectional view along 2-2 of Figure 1;
• Figure 3 is a cross-sectional view along 3-3 of Figure 2;
• Figure 4 is a partial perspective view of the inner end of the sleeve of this mechanism;
• Figure 5 is a view similar to Figure 1 showing the mechanism being actuated;
• Figure 6 is a view similar to Figure 3 showing the position of the striker during assembly of the mechanism;
• Figure 7 is a cross-sectional view illustrating the mounting method of this mechanism.

As shown in the drawing, this mechanism essentially comprises a female body (2) inside which a cylindrical sheath (3) is slidably mounted, the outer end of the female body (2) being closed by an anvil (4) comprising one (5) of the ignition mechanism electrodes.

Inside this sheath are housed and fixed a piezoelectric element (6) and a metal stopper (7) whose retention and fixing in the sheaths (3) are ensured by a flange (8).

The cross sections of the female body (2) and the sleeve (3) are shown in Figures 3 and 6.

As shown in Figure 3, the outer perimeter of the female body (2) is square while the inner bore of the sleeve (3) is of circular section.

The internal extension (3a) of the sleeve (3), that is to say its extension beyond the stopper (7), has two slots (9) diametrically opposite and intended to serve as a guide for two pins (11) diametrically opposite of a striker (12) having the shape of a cylinder of circular section capable of sliding in the bore of the same section of the sleeve (3).

As shown more particularly in Figure 4, each longitudinal slot (9) of the sleeve (3) opens at the inner end of this sleeve (3) and has, in the vicinity of this end, a lateral notch (13) whose side (13a), closest to the free interior end of the sheath (3), serves as a retaining element for the striker (12), while its opposite side (13b) serves as a catch notch in the armed position of this striker (12), these two sides (13a) and (13b) of each notch (13) acting on one of the lugs (11) of the striker (12).

Furthermore, the female body (2) has, on each of two of its opposite walls corresponding to the wall parts of the sheath (3) comprising the longitudinal slots (9), a window (14) through which one of the pins (11) of the striker (12).

Each window (14) is wide enough to cover the corresponding longitudinal slot (9) and its lateral notch (13) so as not to hinder the movements of the pins (11) during the rotation of the striker (12) necessary for the operation of the mechanism.

Finally, the female body (2) contains two concentric helical springs (15) and (16) bearing on its bottom wall (2a) by one of their ends and respectively, against the striker (12) and against the inner end of the extension (3a) of the sheath (3). The inner spring (15) constitutes the striker spring (12) while the outer spring (16) constitutes the return spring of the mechanism in the rest position.

Finally, as shown in FIGS. 1 and 5, the transverse sides of each window (14) are inclined relative to the longitudinal axis of the mechanism so as to each constitute a ramp, respectively, for engagement (14) and for triggering (14b), these two ramps being inclined in the same direction in order to produce opposite effects.

In the drawing, the mechanism has been shown with the female body (2) placed above the sheath (3) but of course the reverse arrangement can be adopted when mounting this mechanism in a lighter.

The operation of this mechanism, of a known type, is as follows:

At rest, as a result of the action of the springs (16) and (15) on the sheath (3) and on the striker (12), the pins (11) of which are engaged in the notches (13), the sheath ( 3) is in its most extended position relative to the female body (2).

The actuation of the mechanism consists in increasing the engagement of the sheath (3) in the female body (2) by displacement of one, of the other, or of these elements.

In the rest position, as shown in Figures 1 and 2, each lug (11) of the striker (12) bears against the bottom of the engagement ramp (14a) of the corresponding window (14).

During the increase in the engagement of the sheath (3) in the female body (2), with corresponding increase in the compression of the springs (15) and (16) due to the hooking of the lugs (11) on the notches (13b) of the notches (13), the striker (12) accompanies the sheath (3) in its movement relative to the female body (2). Therefore, the pins (11) are spaced from the ramps (14a) of the windows (14) and conversely approach their ramp (14b). As soon as they come into contact with the ramp (14b) of the corresponding window (14), each lug (11) is moved in the direction of the arrow (17), which causes a corresponding rotation of the striker (12). This displacement has the effect of driving the lugs (11) out of the notches (13) and of bringing them into the longitudinal slots (9) with the elimination of any retention against the action of the detent spring (15) which has the effect of project the striker (12) against the stopper (7) thereby causing the spark due to the desired piezoelectric phenomenon. The force tending to bring the sheath (3) and the female body (2) no longer having any reason to be, the operator releases its action and the return spring tends to return the sheath (3) to its position of departure by disengaging it from the female body (2).

During this relative movement of the sheath (3) and the female body (2) in the direction tending to move them away from each other, each lug (11) of the striker (12) moves away from the ramp ( 14b) corresponding and comes into abutment against the latching ramp (14a) of the same window (14), which causes the immobilization of the striker (12) relative to the sheath (3) until the notches ( 13) appear to the right of the lugs (11). At this time, the reaction of the ramps (14a) on the pins (11) tends to move them in the direction of the arrow (18), causing them to engage in the notches (13) with corresponding rotation of the striker (12). The mechanism is then ready for a new actuation.

The object of the present invention is to allow the lugs (11) to be obtained directly in the manufacture of the striker (12) by molding or forging, so as to allow a considerable simplification of the assembly operations of the mechanism while reducing the cost of manufacture of its striker (12).

For this, as shown in Figures 3 and 6, the common section of the internal bore of the female body (2) and the external face of the sleeve (3) has the shape of a double warhead giving it a corresponding transverse dimension to one of the diagonals of the square section of the female body (2) called large diameter (D) greater than all the other transverse dimensions. In addition, the distance (L) separating the free ends of the pins (11) of the striker (12) is, on the one hand, less than the aforementioned large diameter (D) and, on the other hand, greater than the distance separating the internal faces of the walls of the female body (2) in which the windows (14) are formed. It follows from this arrangement that the striker (12) can be engaged in the female body (2), after the springs (15) and (16), with its lugs (11) in alignment with the large diameter (D) as illustrated in FIG. 6, then, be pivoted by approximately 90 ° in the direction of the arrow (19) when the pins (11) are at the level of the windows (14). This engagement is done naturally by pushing the striker (12), and more precisely its lugs (11 using the sheath (3).

To facilitate the aforementioned rotation of the striker (12) when its lugs (11) are at the level of the windows (14), by making it automatic, the inner end of the extension (3a) of the sheath (3) has, on each part of its edge located in the vicinity of the outlet of each longitudinal slot (9) and on the side of this slot not having the notch (13), a ramp (21) inclined in the direction of the longitudinal slot (9) considered. Since it is these ramp parts (21) of the edge of the sheath (3) which bear against the lugs (11) of the striker (12), when the latter is in the position of engagement in the female body (2), this results in a reaction tending to pivot the striker (12) in the direction of the arrow (19) so that this rotation takes place automatically as soon as it is made possible by the windows (14) .

It is easily understood that as soon as the striker (12) has thus pivoted by approximately 90 °, and that consequently its lugs are opposite the slots (9), the detent spring (15) immediately pushes it in the direction of the arrow (22) until the pins (11) are stopped by the ramps (14a) of the windows (14). The mechanism is then ready for engagement as soon as the pressure exerted on the female body (2) and the sheath (3) ceases and tends to bring them closer to one another. After this engagement, the sides (13a) of the notches (13) ensure the retention of the pins (11) in the slots (9) and therefore oppose any disassembly of the mechanism.

It can therefore be seen that the mounting operations of this mechanism are therefore limited to successively engaging in the female body (2) the two springs (15) and (16), the striker (12) in its mounting position illustrated in FIG. 6 , and finally the sheath (3) by pushing the latter into the body (2) until the striker (12) is rotated in its normal position, this rotation being obtained automatically and causing the locking of the mechanism in mounted position.

As a result, all the mounting operations of this mechanism can be carried out automatically and mechanically without manual intervention, which further reduces manufacturing costs considerably.

Claims (3)

1. A piezoelectric igniter mechanism, of the type including a female body (2) having a cylindrical bore in which is engaged a sleeve (3) of complementary external section containing, in order, starting from its external end, a metallic anvil (4) acting as an electrode, a piezoelectric element (6) and a metallic stop (7), whilst between the end (2a) of the female body (2) and the internal end (3a) of the sleeve (3) are disposed two concentric helicoidal springs, of which an external one (16) returns the sleeve (3) and bears against the internal end (3a) of the latter, and the other is an internal release spring (15) bearing on a striker (12) provided with two diametrically opposed lugs (11), each of which is engaged, on the one hand, in a window (14) formed in the adjacent wall of the female body (2), and, on the other hand, in a longitudinal guiding slot (9) formed in the sleeve (3) and open at its internal end (3a) and each of which slots has a notch (13) of which an edge (13b) constitutes a catch for latching the corresponding lug (11) which is normally pushed into it by the action of a ramp (14a) formed in the transverse edge of the associated window (14) furthest from the end (2a) of the female body (2) and against which it is normally applied by the release spring (15), from which catch (13b) it is ejected by application against a ramp (14b), inclined in the same direction as the aforementioned ramp (14a) but having the inverse effect, formed in the opposite transverse edge of the aforementioned window (14) and against which it is applied when the mechanism is operated, in the direction corresponding to an increase in the relative engagement of the sleeve (3) and the female body (2) and to a compression of the two springs (15) and (16), characterised in that, on the one hand, the transverse section of the bore of the female body (2) and that of the sleeve (3) have a non-circular perimeter, in such a way as to have a greater dimension (D) in a direction not passing through the windows (14) of the female body (2) than in other directions, and, on the other hand, the distance (L) separating the free ends of the diametrically opposed lugs (11) of the striker (12) is less than the aforementioned greater dimension (D) of the transverse section of the female body (2) and of the sleeve (3) but greater than the distance separating the two windows (14) of the female body (2).

2. A piezoelectric igniter mechanism according to Claim 1, characterised in that the transverse section of the bore of the female body (2) and the complementary section of the sleeve (3) have the shape of a double ogive.

3. A piezoelectric igniter mechanism according to Claim 1 or Claim 2, characterised in that the internal end (3a) of the sleeve (3) has, on its edge and in the vicinity of each longitudinal slot (9), on the side of the large dimension (D) of its transverse section, a ramp (21) inclined in the direction of the relevant longitudinal slot and intended to bear against one of the lugs (11) of the stricker (12) in the engaged position.

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