DE102011014362A1 - Linear actuator for vehicle occupant restraint system, has piston, clamp and locking element that are coordinated to transmit tensioning force from clamp/piston to locking element if piston and clamp are moved in preset direction - Google Patents

Abstract

The linear actuator has cylinder tube (12) having guided traction unit in which a piston (18) movable in opposite directions is arranged. A clamp (22) and a locking element (24) which is movable only in direction (A) are arranged in the piston. The piston, clamp and locking element are coordinated so that tensioning force is transmitted and is not transmitted from the clamp or the piston to the locking element if the piston and the clamp are moved in the directions (A,B) respectively. An independent claim is included for vehicle occupant restraint system.

Description

The invention relates to a linear drive for a vehicle occupant restraint system, in particular for a buckle or Endbeschlagstraffer. The invention further relates to a vehicle occupant restraint system with a buckle or Endbeschlagstraffer and a force limiting device.

With a belt tensioner, the belt slack of a seat belt can be eliminated in the event of a vehicle collision. Belt tensioners can be arranged either on the belt retractor, on the belt lock or on the end fitting of the safety belt system. Gurtschloss- or Endbeschlagstraffer are usually driven by a linear drive. Often come pyrotechnic linear actuators with a gas generator and a piston / cylinder unit is used, wherein the piston is an accelerated by the gas generator provided by the compressed gas drive element whose movement is used for the belt tightening. For this purpose, the piston is usually connected to a rope which acts directly or indirectly on the buckle or on the end fitting.

Such a pyrotechnic linear drive with a gas generator is for example from the DE 10 2006 032 447 A1 known. A displaceable in a cylinder piston has a fixedly connected to a rope locking member with an inclined clamping surface and a slidably guided on the rope sleeve. Several blocking bodies (balls) are arranged displaceably between the blocking part and the inner wall of the cylinder. During a tightening process, the pressurized gas generated by the gas generator exerts a force on the sleeve, so that the sleeve and the locking part adjacent thereto are displaced in a first direction without the locking bodies blocking this movement. As a result, a buckle connected to the rope is pulled in a bit. If a tensile force is exerted on the cable opposite to the first direction, the locking bodies will run against the clamping surface which is at an angle and cause a blockage between the locking part and the cylinder which prevents further movement of the locking part and the cable in this direction.

Is the belt tensioner additionally equipped with a force limiting device, such. B. in the DE 202 18 869 U1 As shown, by controlled conversion of the kinetic energy of the vehicle occupant, the webbing force acting on the occupant can be reduced by allowing a limited withdrawal of the previously tightened webbing while performing forming work. Since both the pretensioner and the force limiting device are coupled to the cable, a reversal of the direction of movement of the cable is to be ensured in this case.

In the case of known coupled linear drives, however, the maximum usable travel for the force limitation is at most as great as the previously traveled tension path (length of the cable section pulled in during the tightening). This is due to the fact that, when the force is limited, the piston (part) attached to the cable comes to rest against the cylinder housing after the straining path has been traveled in the reverse direction. Thus, the starting position is reached (as before the tightening), and there is no further pull-out possible.

For non-coupled linear actuators, the tightening power must not be higher than the level of force limitation, otherwise the path available for the force limitation will be used up or reduced during the tightening process.

The object of the invention is to enable a design of the usable for the force limitation way, which is not limited by the Straffweg.

This object is achieved by a linear drive with the features of claim 1. Advantageous and expedient embodiments of the linear drive according to the invention are specified in the accompanying subclaims.

The linear drive according to the invention for a vehicle occupant restraint system, in particular for a buckle or Endbeschlagstraffer, comprising a cylinder tube, a guided in the cylinder tube traction means, displaceable in the cylinder tube in opposite directions piston, arranged on the traction means, coupled to the piston clamping part, and a in the cylinder tube in a first direction displaceable locking member, which is prevented from moving in a direction opposite to the first direction of the second direction. According to the invention, the traction means, the clamping member and the locking member are coordinated so that upon movement of the piston and the clamping member in the first direction, a force transmission from the clamping member or piston takes place on the locking member. In a movement of the traction means in the second direction, however, there is no significant force transmission from the locking part on the clamping part or on the piston.

The invention is based on the recognition that a Kraftbegrenzungsweg independent of the Straffweg only by decoupling the essential for the force limiting components of the components required for tightening (apart from the traction means used in both cases) can be achieved. According to the invention, the Straffweg independent interpretation of the force limiting path is achieved in that - in contrast to the tightening process - in a movement of the traction means in Extraction direction no significant force transmission from the locking part takes place on the clamping part or on the piston, ie the clamping part and the piston can be solved at the onset of force limitation of the locked locking part.

Particularly advantageous is an embodiment of the linear drive according to the invention, in which upon movement of the piston and the clamping part in the first direction, a firm connection of the clamping part is made or maintained with the traction means. As a result, an effective transfer of the tensioning force is ensured on the traction device in each case. The clamping part can either be already pre-mounted on the traction means, or the position of the clamping part on the traction means is determined only during assembly.

The fixed connection of the clamping part with the traction means can be produced or supported by applying a clamping force acting between the clamping part and the traction means in the first direction by means of the locking part during the movement of the piston and the clamping part. The blocking part thus fulfills a dual function: on the one hand, it contributes significantly to the transfer of the tensioning force to the traction means; on the other hand it locks after completion of the tightening process, ie. H. it basically prevents a return movement of the previously retracted traction means.

According to a preferred embodiment of the invention, the clamping part has a wedge-shaped portion which engages in the first direction on the locking member during the movement of the piston and the clamping part. Via the wedge shape, a force acting on the clamping part in the longitudinal direction of the linear drive can be converted into a clamping force with components which are directed onto the traction means.

For the required force in the longitudinal direction of the linear drive can provide a blocking part with a matched to the wedge shape of the clamping part funnel-shaped portion in such an embodiment of the clamping part. When the wedge-shaped portion of the clamping member is pressed into the funnel-shaped portion of the locking member, thereby the desired clamping force is generated in an efficient manner.

For a better power transmission from the locking part on the clamping part during tightening, a support member may be provided, on which the locking body is supported during the movement in the first direction. As a support member may in particular be provided a positive guide for locking body of a locking device which prevents the locking member from moving in the second direction B. Thus, the locking device fulfills a dual function.

In order for the traction means to be able to move in the second direction with the clamping part and the piston during the force limitation, it must be ensured that the pressurized gas located between the gas generator of the linear drive and the piston after the tightening can escape so as not to block the movement , This can be achieved according to a preferred embodiment in that a seal is arranged on the blocking part, which seals a pressure chamber formed between a gas generator and the piston, wherein the seal remains in a movement of the traction means in the second direction on the locking part. When the clamping part and the piston move away from the blocking part with the seal located thereon during the force limitation, an overflow of the compressed gas from the pressure chamber into the region between the clamping part and the blocking part is thus possible.

In principle, when tightening for a force transmission between the pressurized piston and the clamping part, a loose contact of the clamping part on the piston is sufficient. However, the clamping part can also be firmly connected to the piston or formed integrally with the piston or integrally with the piston.

A first development of the invention provides that a damping element is coupled to the blocking part. The damping element can be provided to release a certain distance of the traction means in the second direction after completion of the tightening process with a time delay.

According to a second development of the invention, a force-limiting element acting in the second direction of movement is coupled to the traction means. The force limiting element may be compressed after tightening by performing deformation work preferably against the locked locking member to allow a controlled Zugmittelauszug and thereby reduce the force acting on the vehicle occupant belt force.

In an advantageous embodiment of the two developments, the force limiting element between the locking part and the damping element is arranged. In this way, the two functionalities of further education can be effectively combined.

The invention also provides a vehicle occupant restraint system having a buckle or end fitting pretensioner and a force limiting device, both of which engage the traction means. The vehicle occupant restraint system is characterized in that the Gurtschloss- or Endbeschlagstraffer a inventive Linear drive has. The linear drive according to the invention for a buckle or Endbeschlagstraffer can be particularly advantageous combined with a force limiting element having a force limiting device, which is coupled as well as the tensioner to the traction means. In particular, the locked after the tightening locking member can be used as a support for compression of a force limiting element.

Further features and advantages of the invention will become apparent from the following description and from the accompanying drawings. to which reference is made. In the drawings show:

1 essential components of a linear drive according to the invention:

2 the components off 1 in the assembled state;

3 a sectional view of a linear drive according to the invention in a starting position;

4 the linear drive in an end position after the tightening process;

5 an enlarged detail of the 4 ; and

6 the linear drive during an adjoining the tightening force limit.

In the 1 and 2 are essential components of a linear drive for a buckle or a Endbeschlagstraffer shown. A traction device 10 , here a rope, is coupled at one end to a buckle or to an end fitting of a safety belt system. The traction device 10 is in one (in the 1 and 2 not shown) cylinder tube 12 with two front ends 14 . 16 guided, in which also a piston 18 , a seal 20 , a clamping part 22 , a blocking part 24 , a locking device with a plurality of locking bodies 26 , a force limiting element 28 and a damping element 30 are arranged.

At the first end 14 of the cylinder tube 12 is arranged (not shown in the figures) pyrotechnic gas generator. On the traction device 10 is the piston 18 arranged and opposite the cylinder tube inner wall and the traction means 10 sealed that between the gas generator and the piston 18 a closed pressure chamber 32 is formed (see 3 ).

To the piston 18 coupled, in particular by fixed connection or one-piece or one-piece design with the piston 18 , is one on the traction device 10 arranged clamping part 22 in the form of a clamping sleeve. Basically, it is sufficient if the clamping part 22 on the first cylinder tube end 14 opposite side on the piston 18 loosely so that when the piston moves 18 in a first direction to the second cylinder tube end 16 a power transmission from the piston 18 on the clamping part 22 is guaranteed. The clamping part 22 has a wedge-shaped section 34 on, in the direction of the second cylinder tube end 16 rejuvenated. Preferably, the clamping part 22 Already before or during assembly of the linear drive firmly on the traction means 10 pressed.

Also on the train 10 is the blocking part 24 arranged, which is not permanent with the clamping part 22 or the piston 18 connected is. The blocking part 24 has a on the wedge shape of the clamping part 22 tuned funnel-shaped section 36 on. On the outside has the locking part 24 at least one obliquely employed blocking area 38 extending in the direction of the second cylinder tube end 16 the cylinder tube inner wall approaches.

On the blocking part 24 is a seal 20 arranged in the form of an O-ring The seal 20 seals the between the piston 18 and the gas generator of the linear actuator pressure chamber formed 32 to the cylinder tube 12 down. The seal 20 lies on the second cylinder tube end 16 facing side on a collar of the locking part 24 so that the seal 20 during a movement of the blocking part 24 in the direction of the second cylinder tube end 16 from the blocking part 24 is taken.

Between the oblique blocking surface 38 of the blocking part 24 and the cylinder tube inner wall are a plurality of locking bodies 26 , here balls, slidably arranged. In addition, there may be a forced operation 40 for the locking body 26 be provided. The locking bodies 26 , possibly together with the forced operation 40 , Form a locking device for the locking part 24 ,

On the piston 18 and the clamping part 22 opposite side of the locking part 24 engages a substantially tubular force limiting element 28 on, extending in the longitudinal direction of the cylinder tube 12 extends. To the force limiting element 28 again is a substantially tubular damping element 30 coupled, which is also in the longitudinal direction of the cylinder tube 12 extends. The damping element 30 is fixed with the traction means 10 connected. About the damping element 30 is also the force limiting element 28 to the traction means 10 coupled.

That firmly with the traction means 10 connected damping element 30 is particularly elastically or plastically deformable or limited in this direction by force in a direction opposite to the first direction A second direction B. displaceable. The force limiting element 28 is designed very stiff in comparison, but can be plastically deformed by very high force in the second direction B for the purpose of energy conversion, in particular upset. This is the force limiting element 28 dimensioned so that in the cylinder tube 12 a certain amount of free space for deformation is available.

In the in 3 shown starting position of the linear drive protrudes the clamping part 22 with its wedge-shaped section 34 in the funnel-shaped section 36 of the blocking part 24 into it. To initiate a tightening process, the gas generator is activated. The gas generator in the pressure chamber 32 supplied pressurized gas exerts a pressure on the piston 18 so that it is shifted in the first direction A.

There is a power transmission from the piston 18 over the clamping part 22 on the blocking part 24 , The piston 18 Therefore, takes on the displacement in the first direction A, the clamping part 22 , the blocking part 24 with the seal 20 , the locking body 26 and the force limiting element 28 and the damping element 30 With.

Because the locking body 26 during the movement in the first direction A due to their inertia and / or due to the forced operation 40 at the tapered end of the locking part 24 remain in a position in which they have a radial clearance or not at the same time in contact with the locking part 24 and the cylinder tube inner wall do not hinder the displacement of the other components. Also the seal 20 remains in its position or is against the collar of the locking part 24 pressed, so no compressed gas from the expanding pressure chamber 32 can escape.

Due to the special geometry and arrangement of the clamping part 22 and the blocking part 24 with their wedge-shaped or funnel-shaped sections 34 and 36 a clamping force is generated, which is the clamping part 22 firmly to the traction means 10 suppressed. More specifically, pushing in of the wedge-shaped section creates 34 of the clamping part 22 in the funnel-shaped section 36 of the blocking part 24 at the tapered end of the clamping part 22 a force acting radially on the traction means 10 directed components. This will cause the connection of the clamping part 22 with the traction means 10 supported. This may possibly be the blocking part 24 , in particular its funnel-shaped section 36 , outside on the forced operation 40 support, which in turn rests against the cylinder tube inner wall.

Alternatively, if the clamping part 22 initially not firm with the traction means 10 was connected by the clamping force generated in the movement in the first direction A, a firm connection of the clamping part 22 with the traction means 10 produced.

In both cases, therefore, the pressure gas from the piston 18 applied tension reliably on the traction means 10 transferred so that this is taken in the first direction A. As a result, the desired Gurtbandeinzug is achieved.

4 shows the linear drive in an end position, which this occupies at the end of the tightening process. The displacement of the piston 18 and the other moving components is by striking the damping element 30 at a stop 42 at the second cylinder tube end 16 stopped.

Now, by the forward displacement of the vehicle occupant, a force on the traction means 10 exercised in the second direction B, run the lock body 26 due to their inertia and / or due to the forced operation 40 on the blocking area 38 of the blocking part 24 on and between the blocking part 24 and the cylinder tube 12 trapped. The locking device thus ensures a block between the locking part 24 and the cylinder tube 12 so that the blocking part 24 is prevented from further movement in the second direction B.

Previously, using the damping element 30 even a limited yielding of the traction means in the second direction B are allowed, regardless of whether then actually uses a force limit or not.

The force limiting element 28 on the one hand to the locked locking part 24 on the other hand via the damping element 30 to the traction means 10 coupled exceeds after the tightening of the vehicle occupant to the traction means 10 applied force in the second direction B a certain degree, sets a plastic deformation of the force limiting element 28 one. The force limiting element 28 is compressed while performing deformation work, whereby a controlled webbing extension is made possible.

Due to the special geometry and arrangement of the clamping part 22 and the blocking part 24 with their wedge-shaped or funnel-shaped sections 34 and 36 be during a movement of the traction device 10 in the second direction B no forces from the locked locking part 24 on the clamping part 20 or the piston 18 transfer. This means that the wedge connection between the clamping part 22 and the locked locking part 24 can solve, as in 6 shown. Thus, neither the blocking part take 24 still the clamping part 22 or the piston 18 significant influence on the movement of the traction device 10 in the second direction.

Because the clamping part 22 after completion of the tightening no more force on the blocking part 24 exerts and the connection between the clamping part 22 and the locked locking part 24 releases, remove the clamping part 22 and the piston 18 from the remaining seal on the locking part 20 , Therefore, compressed gas can escape from the pressure chamber 32 escape and into the expanding area of the cylinder tube 12 between the clamping part 22 and the seal 20 overflow, as in 5 indicated. Also the compressed gas in the pressure chamber 32 thus does not constitute a major obstacle to the movement of the traction device 10 in the second direction 12 Depending on the dimensioning, the overflow can have a specific influence on the force limitation.

Overall, therefore, the available for the power limit way is not limited by the effect or the position of the components required for tightening. The maximum Kraftbegrenzungsweg (cable pullout) can be interpreted in the construction shown rather so that the end is reached only when a further compression of the force limiting element 28 is no longer possible.

In principle, other geometries of the clamping part 22 and the blocking part 24 possible to ensure the described functionality during tightening and during the subsequent force limitation; in particular, the wedge-shaped and funnel-shaped sections 34 respectively. 36 of the clamping part 22 and the blocking part 24 be provided on the other component and / or in another orientation. It is essential that during tightening a clamping force on the traction means 10 is exercised, which is a transfer of the tensioning force from the piston to the traction means 10 ensures, and that during a movement of the traction device 12 in the second direction B, a decoupling of the clamping part 22 and the piston 18 from the blocking part 24 takes place.

LIST OF REFERENCE NUMBERS

10

traction means

12

cylinder tube

14

first cylinder tube end

16

second cylinder tube end

18

piston

20

poetry

22

clamping part

24

blocking part

26

blocking body

28

Force limiting element

30

damping element

32

pressure chamber

34

wedge-shaped section

36

funnel-shaped section

38

blocking surface

40

forced control

42

attack

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102006032447 A1 [0003]
• DE 20218869 U1 [0004]

Claims (12)

Linear drive for a vehicle occupant restraint system, in particular for a seat belt buckle or end fitting tensioner, with a cylinder tube ( 12 ), one in the cylinder tube ( 12 ) guided traction means ( 10 ), one in the cylinder tube ( 12 ) in opposite directions A, B slidable piston ( 18 ), one on the traction means ( 10 ), to the piston ( 18 ) coupled clamping part ( 22 ), and one in the cylinder tube ( 12 ) in a first direction A displaceable locking part ( 24 ) prevented from moving in a second direction B opposite the first direction A, characterized in that the traction means ( 10 ), the clamping part ( 22 ) and the blocking part ( 24 ) are coordinated with each other so that during a movement of the piston ( 18 ) and the clamping part ( 22 ) in the first direction A, a power transmission from the clamping part ( 22 ) or the piston ( 18 ) on the blocking part ( 24 ), and during a movement of the traction means ( 10 ) in the second direction B no significant force transmission from the blocking part ( 24 ) on the clamping part ( 22 ) or on the piston ( 18 ) he follows. Linear drive according to claim 1, characterized in that during a movement of the piston ( 18 ) and the clamping part ( 22 ) in the first direction A a firm connection of the clamping part ( 22 ) with the traction means ( 10 ) is produced or maintained. Linear drive according to claim 2, characterized in that by means of the locking part ( 24 ) during the movement of the piston ( 18 ) and the clamping part ( 22 ) in the first direction A between the clamping part ( 22 ) and the traction means ( 10 ) acting clamping force is applied. Linear drive according to one of the preceding claims, characterized in that the clamping part ( 22 ) a wedge-shaped section ( 34 ), which during the movement of the piston ( 18 ) and the clamping part ( 22 ) in the first direction A at the blocking part ( 24 ) attacks. Linear drive according to claim 4, characterized in that the locking part ( 24 ) one on the wedge shape of the clamping part ( 22 ) tuned funnel-shaped section ( 36 ) having. Linear drive according to one of the preceding claims, characterized in that the blocking body ( 24 ) is supported on the movement in the first direction on a support element, in particular on a forced operation ( 40 ) for blocking bodies ( 26 ) a locking device, the locking part ( 24 ) prevents movement in the second direction B. Linear drive according to one of the preceding claims, characterized in that on the locking part ( 24 ) a seal ( 20 ) arranged between a gas generator and the piston ( 18 ) formed pressure chamber ( 32 ) seals, with the seal ( 20 ) during a movement of the traction means ( 10 ) in the second direction B on the blocking part ( 24 ) remains. Linear drive according to one of the preceding claims, characterized in that the clamping part ( 22 ) firmly with the piston ( 18 ) or in one piece with the piston ( 18 ) or in one piece with the piston ( 18 ) is trained. Linear drive according to one of the preceding claims, characterized in that the locking part ( 24 ) a damping element ( 30 ) is coupled. Linear drive according to one of the preceding claims, characterized in that on the traction means ( 10 ) acting in the second direction of movement B force limiting element ( 28 ) is coupled. Linear drive according to claim 9 and 10, characterized in that the force limiting element ( 28 ) between the blocking part ( 24 ) and the damping element ( 30 ) is arranged. Vehicle occupant restraint system, with a buckle or Endbeschlagstraffer and a force limiting device, both on the traction means ( 10 ), characterized in that the Gurtschloss- or Endbeschlagstraffer has a linear drive according to one of the preceding claims.

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