DEVICE FOR FIRING A PYROTECHNIC PROPELLENT COMPOSITION

Abstract: A device for firing a pyrotechnic propellent composition having a sensor mass (3) which for firing purposes releases a locking lever (4) which in the rest position bears lockingly against a ring (9) of the firing pin (1).

Description: Device for firing a pyrotechnic propellent composition The invention concerns a device as set forth in the classifying portion of claim 1. A device of that kind serves for the firing of a pyrotechnic propellent composition, in particular of a gas generator. Propellent compositions of that kind are used in particular in motor vehicles in order to drive components, for example a piston or a rotary piston in a tube or a housing so that safety components on the vehicle are moved from a normal position into a safety position. For example a telescopic steering column is reduced in length by drive devices of that kind. It is also known for safety belts which bear loosely against the body of the vehicle occupants to be tightened by means of pyrotechnically operated belt tensioners. It is also known for a filling gas to be produced by means of a fired propellent composition, for filling air bags. To fire the respective propellent compositions, it is known to drive a firing or striker pin in its axial direction by means of a drive spring. There is also a locking means which holds the drive spring and therewith the firing pin in the rest position. In the event of excessive acceleration a sensor mass is moved, by which the locking means is released so that the drive force of the spring can act on the firing pin (EP 0 529 501 Al). The object of the invention is to provide a device of the kind set forth in the opening part of this specification, which is acceleration- sensitive, comprises mechanical components, and can be universally employed. In accordance with the invention that object is attained by the characterising features of claim 1. The drive spring can be held in a prestressed rest position by means of the locking lever which is supported at a stationary location, in particular of the sensor housing. A torque acts on the locking lever, in the direction of its release position, due to the prestressing of the drive spring. In the rest position, that is to say below a given triggering threshold, the sensor mass provides that the release moment which acts on the locking lever is carried at an abutment which in particular can be provided on the sensor mass. Preferably, besides a first support location which is supported in particular on a firing pin actuating means and with which the drive force of the drive spring is carried, the locking lever may have a second support location which, as viewed in the drive direction, is displaced outwardly and which is supported stationarily, in particular on the sensor housing. That arrangement ensures that for release of the locking lever, which is caused by the moved sensor mass, the locking means is moved into its release position by the drive force of the drive spring and at the same time the drive force of the spring is utilised for the firing procedure. For that purpose the locking lever may have a third support location which bears against an abutment, in particular on the sensor mass. Preferably the locking lever is in the form of a double-sided locking lever whose axis, which is not stationary, is formed by the first support location or is in the irmiediate vicinity of the first support location, and in which the second and third support locations are provided at the two sides of the lever. Preferably a ring is provided on the firing pin as the firing pin actuating means. The ring may be formed integrally with the firing pin. It may however also be displaceable by the drive force of the drive spring towards the firing pin. In the rest condition the firing ring bears against the first support location of the locking lever under the prestressing effect of the drive spring. When the locking means is released, the ring which can be in the form of a striker or firing ring is moved towards an anvil on the firing pin and is impacted thereagainst. Due to the impact, the firing pin is accelerated towards the firing means for the propellant and upon impact thereof fixes the propellant. For guidance of the striker ring the firing pin may have a shank along which the striker ring is accelerated towards the anvil by the drive spring. SUBSTITUTESHEET{RULE26) The firing pin is mounted with its shank on the sensor housing, at the end which is opposite to the firing tip. That mounting configuration ensures that the firing pin is mounted with its tip that projects out of the sensor housing, movably in a radial direction with respect to its axis, at its end that is opposite to the firing tip. That arrangement provides for accurate alignment of the firing pin with a firing opening in a housing which can be fitted on to the sensor housing and in which the propellant is disposed. The alignment with the firing opening ensures that the firing tip of the firing pin impinges precisely on the firing device of the propellant upon acceleration thereof by the drive spring. Production tolerances can be compensated by virtue of that design configuration, and this arrangement always guarantees that the firing pin is aligned with the propellant firing device. It is also possible for the fixing pin actuating means to be pivotable about an axis, the drive spring acting on the firing pin actuating means by way of a lever arm. As in the fixst embodiment the firing pin is held in a pre-positioned condition with respect to the firing device and the firing pin actuating means can be impacted on to the pre-positioned firing pin. In that respect the impact surface on the firing pin may be of relatively large size so that production tolerances in regard to alignment of the firing pin with respect to the fixing device do not have a detrimental effect. It is also possible, as in the first embodiment, for the firing pin and the firing pin actuating means to be produced in one piece and for same to be pivoted about the pivot axis. The drive spring and the firing pin actuating means may also comprise one piece. For that purpose the drive spring is in the form of a leaf spring which is subjected to a prestressing effect and on which the firing pin actuating means is possibly integrally formed. The invention will be described in greater detail hereinafter by means of embodiments by way of example with reference to the drawings in which: Figure 1 shows a first embodiment, Figure 2 shows a second embodiment, Figure 3 is a plan view of a configuration for parallel guidance of the sensor mass, which can be used in the embodiments, Figure 4 shows a further configuration which can be used in the embodiments, Figure 5 shows a third embodiment, Figure 6 shows a fourth embodiment, Figure 7 shows a fifth embodiment, and Figure 8 shows a specific configuration of the locking lever. The same references are used in the Figures for components which have the same action. Reference 7 denotes a sensor housing in which a striker or firing pin 1 is mounted with an end 14 of its shank 16, which is in opposite relationship to the striker or firing tip. A ring 9 which acts as a striker ring is displaceably mounted on the shank 16 of the firing pin 1. The ring 9 on which a drive spring 2 acts in the drive direction is held in the illustrated rest position by a locking means in the form of a locking lever 4. For that purpose the locking lever 4 has a first support location 5. The locking lever 4 also has a second support location 6 which is supported at a stationary location 19 on the sensor housing 7. The striker pin is mounted in a force-free condition with its shank 16 between two loose mountings, in the housing. It serves for axially guiding the ring 9 when the latter is moved towards an anvil 15 provided on the striker pin 1. A sensor mass 3 is also provided in the housing. The sensor mass 3 is mounted on a parallel guide means 11 which can be in the form of parallel link springs. The sensor mass 3 is movable against the force of a sensor spring 12 which in the illustrated embodiment is in the form of a coil spring. The dixection of movement is indicated by an arrow 13. When the illustrated device is arranged in a vehicle, the direction of movement of the sensor mass 3 against the force of the spring 12 is the same as the direction of forward travel, that is to say the direction of the arrow 13. The force of the sensor spring 12 can be adjusted by way of means which are not shown in greater detail. In the rest position shown in the Figure, a third support location 10 on the locking lever 4 bears against an abutment on the sensor mass 3. The abutment on the sensor mass carries the torque which is exerted on the locking lever 4 by the drive spring 2 in the illustrated rest position. The illustrated mechanical firing device is held in readiness in that rest position. The locking lever 4 is in the form of a double-sided lever. Itε axis of rotation, which is not stationary, is formed in the reqion of the first support location 5. The lever arm between the third support location 10 and the first support location 5 is longer than the lever arm between the first support location 5 and the second support location 6. In addition, with respect to a pin axis 8 along which the ring 9 can be driven by the spring 2, the first support location 9 is provided on the locking lever 4 at an inward position and the second support location 6 is provided on the locking lever 4 at an outward position. In the illustrated rest position the operative torque is carried by the abutment of the sensor mass 3, against which the third support location 10 of the locking lever 4 bears. Assembly of the illustrated device is effected from below in the Figure. After installation of the individual components, the lower side of the sensor housing 7 is closed by a cover 20. An assembly securing means holds the components in the correct position. A housing 18 which has a firing device 22, for example a mechanical fuse, is arranged on the sensor housing 7 in such a way that the firing pin 1 is disposed with its firing tip opposite the firing device 22. In order to align the firing pin 1 with the firing device 22, the housing 18 in which the propellant is arranged has a fixing opening 17. The housing 18 is arranged on the outside of the sensor housing 7 in such a way that the firing pin tip of the firing pin 1 projects into the firing opening 17, as shown in the Figure. That ensures that the firing pin tip is aligned with the firing device 22 in the dixection of the firing pin axis 8. Production tolerances can be compensated by virtue of the fact that the firing pin 1 which is mounted at its opposite end 14 to the sensor housing 7 is movable in a radial direction with respect to its axis 8 so that alignment with the firing device 22 is always guaranteed when the firing pin 1 projects into the firing opening 17 of the housing 18. The illustrated fixing device can be combined in that way with any housings 18 which contain gas generators or propellants. If, in the event of an excessive level of acceleration, that is to say when a given acceleration value is exceeded, the sensor mass 3 is moved in the direction of the arrow 13 against the force of the spring 12, the support surface 10 of the locking lever 4 is released so that the release moment produced by the spring 12 comes into operation and the locking means is released. At the same time the ring 9 which acts as a striker ring is moved along the shank 16 towards the anvil 15 and impacts thereagainst at high speed so that, as a reaction thereto, the firing pin 1 impacts with its striker tip against the firing device 22 and fires the propellant. When that happens the drive spring 2 is supported against the sensor housing 7 and drives the ring 9 in the described manner after the first support location 5 has been moved away from the ring 9 by the release moment. The spacing of the striker ring 9 from the anvil 15 is of sufficient magnitude so that the drive spring 2 produces an adequate speed or acceleration of the striker ring 9 and the firing pin 1 fires the firing device 22. It is also possible for the ring 9 to be carried fixedly on the shank 16 of the firing pin 1 or to be formed in one piece with the firing pin 1. In that case the shank together with the ring 9 fixedly disposed thereon is also moved together with the firing pin 1 towards the fuse 22 when the locking means is released by the sensor mass 3. In the embodiment shown in Figure 2 transverse link springs which form the parallel guide means have damping loops or bows 23 and 24. The damping loop 23 acts in the longitudinal direction of the vehicle to have an osciliation-damping effect on deflections of the sensor mass 3. A damping loop 24 acts transversely to the longitudinal direction of the vehicle to have an oscillation-damping effect on deflections of the sensor mass 3. That prevents the spring-mass system of the sensor from being excited to a condition of resonance oscillation, as a result of 5 external vibration phenomena. Figure 3 is a plan view of a further embodiment of a parallel guide means for the sensor mass 3. For that purpose the arrangement has transverse link springs for forming the parallel guide means. The parallel link springs ore secured for cxanple by rivets 26 tc the sensor 10 mass 3 and supported with respect to the housing 7 at securing locations 25. That ensures that the sensor mass 3 can be deflected in the direction of travel in the housing 7 against the force of the sensor spring (not shown). The embodiment illustrated in Figure 4 has a feeling or sensing 15 device 27 which is of a resilient configuration and which feels or senses a respective belt reel periphery 30. The belt reel is part of a safety belt retractor which is not illustrated in greater detail herein. Depending on the respective periphery or diameter of the belt reel, a blocking projection 28 is in engagement or out of engagement with an 20 engagement location 29 of the sensor mass 3. If for example the safety belt webbing is completely wound on to the belt reel (outer belt reel periphery 30) the blocking projection 28 is in a condition of engagement with the sensor mass 3 so that movement of the sensor mass 3 is blocked. When the diameter of the belt reel 25 periphery is smaller, for example when the safety belt is fitted, the blocking projection 28 is in a condition of being out of engagement with the sensor mass so that the sensor mass can move in response to excessive acceleration or deceleration of the vehicle. When the blocking projection 28 is in a condition of engagement 30 with the sensor mass 3, then for example upon txanspoxtation of the belt retractor which is provided with the device according to the invention, it can be blocked to prevent movement thereof. That blocking action can also be provided when the vehicle or the safety belt is in a park position. In the embodiment shown in Figure 5 the striker or firing pin 1 is held in its pre-positioned condition with respect to the firing device 22. The firing pin 1 is disposed in an opening of the housing 7, which opening is disposed immediately opposite the firing device 22. A firing pin actuating means 31 is arranged rotatably about an axis 30. The drive spring 2 acts on the fixing pin actuating means 31. The firing pin actuating means 31 is held in the rest position by the locking lever 4 in the same manner as in the case of the embodiments of Figures 1 and 2. After release of the locking lever 4 the firing pin actuating means 31 is driven by way of a IPVPΓ arm 35 by the drive spring 2 which is in I e form of a tension coil spring, and is impacted against an impact surface, which is of relatively large size, of the firing pin 1. The fixing pin 1 is accelerated in the opening in the housing 7 towards the firing device 22 and the latter is fired. The embodiment illustrated in Figure 6 has a drive spring 34 in the form of a curved leaf spring. The spring force acts by way of a lever arm 36 about the pivot axis 30 on a fixing pin actuating means 33 which is formed on the spring in the form of a projection. After release of the locking lever 4 the firing pin actuating means 33 will impact against the firing pin 1 so that it fires the firing device 22, as in the embodiment of Figure 5. In the ernbodiment shown in Figure 7 the firing pin 1 is formed at the front end of the firing pin actuating means 31. As in the embodiment of Figure 5, the drive spring 2 acts by way of the lever arm 35 on the firing pin actuating means 31 which is formed in one piece, to actuate the firing pin 1. As can be seen from Figure 8 the locking lever 4 can have a projection which, upon release thereof, acts as a pivot point 37, with which projection the locking lever 4 can bear against the firing pin actuating means 31. The locking lever 4 can be additionally supported with the pivot point 37, in the embodiment shown in Figures 1 and 2 in which the fixing pin actuating means is in the form of a striker ring. When the locking lever 4 is released the moment imparted by the drive spring 2 or the drive spring 34 respectively acts on the locking lever in such a way that it is rotated about the pivot point 37. As can be seen from Figure 8, the support surfaces 5 and 6, between which the release moment becomes operative, are arranged in mutually displaced relationship whereby the force transmitted to the support surface 5 by the drive spring 2 by way of the fixing pin actuating means 9 or 31 respectively produces a torque by which the locking lever 4 is rotated about the pivot axis 37 after the sensor mass 3 has moved away from the support surface 10 in the direction of the arrow 13, when in its locking position, and is thereby released.

Claims: CLAIMS 1. A device for fixing a pyrotechnic propellent composition comprising a firing pin drivable by a drive spring, a locking means which holds the drive spring in a prestressed rest condition, and a sensor mass which is moved upon excessive acceleration and by which the locking means can be released, characterised in that the locking means has a locking lever (4) which is supported at a stationary location (19) and which is subjected to the action ot a release moment due to the prestressing of the drive spring (2; 34) and which is held in the rest position by the sensor mass (3). 2. A device according to claim 1 characterised in that the locking lever ( .4) has support locations (5, 6) which are disposed in mutually displaced relationship in the drive direction and of which a first support location (5) carries the drive force of the drive spring (2) and a second support location (6) bears against the sensor housing (7). 3. A device according to one of claims 1 and 2 characterised in that the firing pin (1) is linearly drivable in the dixection of its longitudinal axis (fixing pin axis 8). 4. A device according to one of claims 1 to 3 characterised in that the firing pin (1) is held in a pre-positioned condition with respect to a firing device (22) of the pyrotechnic propellent composition and that a firing pin actuating means (9; 31; 33) drivable by the drive spring (2; 34) can be impacted against the firing pin (1). 5. A device according to one of claims 1 to 4 characterised in that the drive spring (2) is in the form of a coil spring which acts on a ring (9) on the firing pin (1) for transmission of the drive force. 6. A device according to one of claims 1 to 5 characterised in that the first support location (5) engages the ring (9). 7. A device according to one of claims 1 to 6 characterised in that the locking lever (4) has a third support location (10) which bears against the sensor mass (3) in the rest position. 8. A device according to one of claims 1 to 7 characterised in that the first support location (5) forms an axis, which is not stationary, of the locking lever (4) which is of a double-sided configuration, and the second and third support locations (6, 10) are provided at the two sides of the lever. 9. A device according to claim 8 characterised in that the lever arm at the side of the lever at which the third support location (10) is provided is longer than the lever arm at which the second support location (6) is provided. 10. A device according to one of claims 1 to 9 characterised in that the sensor mass (3) is guided by means of a parallel guide means (11) on the sensor housing (7). 11. A device according to claim 10 characterised in that the parallel guide means (11) has transverse link springs. 12. A device according to claim 10 or claim 11 characterised in that the parallel guide means (11) has an oscillation-damping action. 13. A device according to one of claims 1 to 12 characterised in that the sensor mass (3) is guided in parallel relationship to the firing pin axis (8). 14. A device according to one of claims 1 to 13 characterised in that the sensor mass (3) is movable in opposite relationship to the direction of the force of a sensor spring (12). 15. A device according to claim 14 characterised in that, when installed in a vehicle, the direction of the force of the sensor spring (12) is directed in opposite relationship to the direction (13) of forward travel of the vehicle. 16. A device according to one of claims 1 to 15 characterised in that the firing pin (1) is guided on the sensor housing (7), at the end (4) of the firing pin which is opposite to the firing tip. 17. A device according to one of claims 1 to 16 characterised in that the ring (9) is in one piece with the firing pin (1). 18. A device according to one of claims 1 to 4 characterised in that the firing pin actuating means (9; 31; 32) is movable with respect to the firing pin (1). 19. A device according to claim 18 characterised in that the firing pin actuating means (9) is guided movably in parallel relationship with the firing pin axis (8). 20. A device according to claim 18 or claim 19 characterised in that the firing pin actuating means (9) which is in the form of a ring is guided on the sensor housing (7) along a surface which extends in parallel relationship to the drive direction and against which the ring (9) bears. 21. A device according to one of claims 18 to 20 characterised in that the ring (9) is in the form of a striker ring which is driven by the drive spring (2) and which is adapted to be movable relative to the firing pin (1) along the firing pin axis (8) and which can be impacted against an anvil (15) secured to the firing pin (1), by the force of the dxive spxing (2) . 22. A device according to one of claims 18 to 21 characterised in that the ring (9) which is in the form of a striker ring is guided on a shank (16) of the firing pin (1). 23. A device according to one of claims 1 to 22 characterised in that the firing pin (1) which projects out of the sensor housing (7) is adapted to be movable perpendicularly to the firing pin axis (8) for alignment with a fixing opening (17) in a housing (18) which can be fitted on to the sensor housing (7). 24. A device according to one of claims 1 to 22 characterised in that a blocking device by which a sensor mass movement can be blocked is actuable in dependence on a device for sensing a belt reel of a safety belt retractor. 25. A device according to one of claims 1 to 4 characterised in that the firing pin actuating means (31; 33) is movable about a pivot axis (30). 26. A device according to one of claims 1 to 4 and 25 characterised in that the firing pin (1) is pivotable about a pivot axis (32). 27. A device according to claim 25 or claim 26 characterised in that the drive spring (2; 34) drives the firing pin actuating means (31; 33) by way of a lever arm (35; 36). 28. A device according to one of claims 1 to 4 and 25 to 27 characterised in that the firing pin (1) and the firing pin actuating means (31; 33) are formed in one piece. 29. A device according to one of claims 1 to 28 characterised in that after release of the sensor mass (3) from the third support surface (10) the locking lever (4) is movable under the influence of the release moment about a pivot point (37) supported at the firing pin actuating means (9; 31). 30. A device according to one of claims 1 to 29 characterised in that the firing pin (1) has an impact surface (38) for the firing pin actuating means (31), which impact surface is of a larger area than the cross-sectional area of the remaining part of the fixing pin.

Inventors: LUDWIG THOMAS, SPECHT MARTIN, LUDWIG, THOMAS, SPECHT, MARTIN
Applicants: ICSRD RUECKHALTESYSTEME FUER F, LUDWIG THOMAS, SPECHT MARTIN, ICSRD RUECKHALTESYSTEME FUER FAHRZEUGSICHERHEIT GMBH, LUDWIG, THOMAS, SPECHT, MARTIN
Application year: 1996
Main classification: B60R22
IPC codes: B60R22, F42C1