Tensioner drive for a seatbelt retractor

Abstract

The invention relates to a tensioner drive (30) for a safety belt device with a gas generator (40), a drive wheel (50) and a feed pipe (60) which connects the gas generator (40) and the drive wheel (50), wherein in the feed pipe (60) there is at least one thrust body (70, 500) which is accelerated after the gas generator (40) is triggered and drives the drive wheel (50). According to the invention, it is provided that the or at least one of the thrust bodies (500) seals the feed pipe (60) during the acceleration phase of the thrust body (500) and is equipped with a venting device which is closed by an inertia element (520) of the thrust body (500) during the acceleration phase of the thrust body (500), and the inertia element (520) is arranged such that, when the thrust body (500) is decelerated, it is displaced relative to the venting device due to inertia and enables a flow of the gas of the gas generator (40) through the thrust body (500) or past the thrust body (500) and through the section of the feed pipe (60) located in front of the thrust body (500) in the direction of thrust in the direction of thrust.

Description

[0001] The invention relates to a tensioner drive for a belt retractor of a safety belt.

[0002] A tensioner drive for a seat belt retractor is known from German patent application DE 10 2008 018 124 A1. The previously known tensioner drive comprises a gas generator, a supply tube, and several thrust bodies located in the supply tube. These thrust bodies are accelerated after the gas generator is triggered, causing the seat belt to retract.

[0003] The invention is based on the object of providing a tensioner drive in which a reduction of excess pressure of the gas of the gas generator is automatically ensured at the end of the tensioning process.

[0004] This object is achieved according to the invention by a tensioner drive for a safety belt device with a gas generator, a drive wheel and a feed pipe which connects the gas generator and the drive wheel, wherein at least one thrust body is present in the feed pipe, which is accelerated after triggering of the gas generator and drives the drive wheel. It is also provided that the or at least one of the thrust bodies seals the feed pipe during the acceleration phase of the thrust body and is equipped with a venting device which is closed by an inertia element of the thrust body during the acceleration phase of the thrust body, and the inertia element is arranged in such a way thatthat when the thrust body is decelerated, it is displaced due to inertia relative to the venting device and enables a flow of the gas from the gas generator through the thrust body or past the thrust body and through the section of the feed pipe located in front of the thrust body in the direction of the drive wheel.

[0005] A key advantage of the tensioner drive according to the invention is that the excess pressure in the supply pipe is automatically relieved by the inertial opening of the venting device at the end of the tensioning process. Thus, after the tensioning process has ended, a backward movement of the drive wheel and a backward movement of the thrust bodies toward the gas generator are no longer impeded. A backward movement may be desired, for example, to enable or at least simplify belt force limitation using a belt force limitation device (e.g., in the form of a torsion bar).

[0006] A further significant advantage of the tensioner drive according to the invention is that the hot gas in the supply pipe only escapes to the outside at the end of the supply pipe; the gas temperature is significantly reduced by passing through or past one or more thrust bodies and by passing through to the end of the supply pipe, so that the risk of burns or fire caused by the gas escaping is eliminated or at least very small.

[0007] With regard to the design of the venting device, it is considered advantageous if it has a gas inlet opening and a passage through the thrust body or is formed by these. Preferably, the inertia element is arranged such that, when the thrust body decelerates, it moves relative to the gas inlet opening, thereby opening the passage through the thrust body, so that the gas from the gas generator can flow through the thrust body toward the drive wheel.

[0008] According to a first particularly preferred embodiment, it is provided that the inertia element is arranged on the outside of the thrust body and closes at least one gas inlet opening to at least one through-channel in the thrust body from the outside during the acceleration phase of the thrust body and the inertia element is displaced relative to the gas inlet opening due to inertia when the thrust body is decelerated, in particular in the final phase of the tensioning process or at the end of the tensioning process, and enables a gas flow of the gas from the gas generator through the gas inlet opening and the through-channel in the direction of the drive wheel.

[0009] Preferably, the inertia element is formed by a ring arranged on the outside of the thrust body.

[0010] In another embodiment of the tensioner drive, which is also considered to be very advantageous, it is provided that the inertia element is formed by a closure element arranged inside the thrust body, which closes at least one gas inlet opening and at least one through-channel in the thrust body during the acceleration phase of the thrust body, and the closure element is displaced relative to the gas inlet opening due to inertia when the thrust body is decelerated, in particular in the final phase of the tensioning process or at the end of the tensioning process, and thereby enables a gas flow of the gas of the gas generator through the at least one gas inlet opening and the at least one through-channel.

[0011] Preferably, the closure element is arranged inside the through-channel and is displaced inside the through-channel due to inertia when the thrust body is decelerated, in particular in the final phase of the tightening process or at the end of the tightening process.

[0012] With regard to the design of the closure element located inside, it is considered advantageous if the thrust body has two or more gas inlet openings which are closed by the closure element during the acceleration phase of the thrust body, and the closure element has in cross section at least two radially outwardly pointing legs which - in the closed position of the closure element - each seal one of the gas inlet openings with their radially outer outer surface.

[0013] Preferably, the gas inlet openings and the radially outward-pointing legs are each arranged rotationally symmetrically.

[0014] Furthermore, it is advantageous to provide a return prevention device that prevents the inertia element from moving backward and the venting device from closing again. This latter design reliably prevents the supply pipe from accidentally resealing at the end of the tightening process, thus preventing or hindering the thrust bodies from moving backward.

[0015] Preferably, after its relative movement, the inertia element is held in its position releasing the venting device by positive locking and / or frictional locking. A positive locking and / or frictional locking can advantageously be achieved by a clamping device, through which the inertia element can only pass in the direction of thrust or into which the inertia element snaps, or by a cone.

[0016] Furthermore, it is considered advantageous if the inertia element is held in a predetermined position by means of a shearable holding device before the gas generator is triggered.

[0017] Preferably, the shearable holding device is designed and / or arranged such that it is sheared off when the tightening process is started and when the thrust body is accelerated, and the inertia element is released when the thrust body is accelerated.

[0018] Alternatively, it can be provided that the shearable holding device is designed and / or arranged in such a way that it is only sheared off due to inertia when the thrust body is braked in the final phase of the tensioning process or only at the end of the tensioning process.

[0019] Furthermore, it is considered advantageous if the thrust body is equipped with a spring device whose spring force supports the inertial movement of the inertial element relative to the venting device.

[0020] Preferably, the spring device is held in an inactive state by means of a lock, and the lock is deactivated when the thrust body is accelerated or decelerated.

[0021] The barrier can be formed, for example, by the aforementioned or another shearable holding device.

[0022] Furthermore, with regard to the design of the tensioner drive, it is considered very advantageous if a plurality of thrust bodies are present in the supply tube, one of which—preferably the first one in the thrust direction or the one closest to the gas generator—is equipped with the venting device and seals the supply tube during the acceleration phase of the thrust body. The thrust bodies located in front of the sealing thrust body in the thrust direction are preferably smaller than the inner diameter of the supply tube and do not seal the supply tube itself.After the inertia element has been moved and after the venting device of the thrust body, which is then no longer sealing, has been opened, the gas flow is enabled through this thrust body or past this thrust body and past the thrust bodies in front of it (which are not sealing from the outset) in the direction of the drive wheel.

[0023] Preferably, the non-sealing thrust bodies are drive balls.

[0024] The invention is explained in more detail below using exemplary embodiments; by way of example, Fig. 1 an embodiment of a tensioner drive according to the invention for a belt retractor in a three-dimensional exploded view, Fig. 2 an embodiment of a feed pipe of the tensioner drive according to Fig. 1 sealing thrust body, whereby the Fig. 2 shows an inertia element of the thrust body in its closed position, Fig. 3 the thrust body according to Fig. 2, showing a release position of the inertia element, Fig. 4 shows a further embodiment of a thrust body which forms the feed pipe of the tensioner drive according to Fig. 1 can seal, whereby the Fig. 4 shows a closed position of an inertial element of the thrust body, Fig. 5 the thrust body according to Fig. 4 in a release position of the inertia element, Fig. 6 shows an embodiment of an inertia element which is used in the thrust body according to the Fig. 4 and Fig. 5 can be used, Fig. 7 shows an embodiment of a pot-shaped inertia element which is held in a predetermined initial position by means of a shearable holding device, and Fig. 8 shows a further embodiment of a thrust body which is held in a predetermined initial position by means of a shearable holding device.

[0025] For the sake of clarity, the same reference symbols are always used in the figures for identical or comparable components.

[0026] The Fig. 1 shows a schematic exploded view of a belt retractor 10 which, among other things, has a belt spindle 20, a tensioner drive 30 and an inertia coupling 35 connecting the tensioner drive 30 and the belt spindle 20.

[0027] The tensioner drive 30 comprises a pyrotechnic gas generator 40, for example in the form of a micro gas generator, a drive wheel 50, a curved feed tube 60 connecting the gas generator 40 and the drive wheel 50, and a plurality of thrust bodies, the first of which, as seen in the thrust direction P, is designated by the reference numeral 500 and seals the feed tube 60. The thrust body 500 functions as a drive piston, which drives the thrust bodies 70 located in front of it in the thrust direction P. The thrust bodies 70 have a smaller cross-section or smaller diameter than the feed tube 60, so that they themselves do not form a seal with respect to the feed tube 60. The non-sealing thrust bodies 70 are, for example, spherical.

[0028] In the Fig. 1 also shows a spring 80 which exerts a spring force on the first thrust body 500 and thus on the thrust bodies 70 located behind it.

[0029] The drive wheel 50 is rotatably mounted between a retaining cap 51 and a retaining plate 52 and has receiving shells 100 into which the thrust bodies 70 engage to drive the drive wheel 50. For this purpose, the thrust bodies 70 are coupled tangentially into the drive wheel 50 and run tangentially past it, engaging in the receiving shells 100, before subsequently reaching a downstream receiving container 110.

[0030] The Fig. 2 shows an embodiment of the thrust body 500 of the tensioner drive 30 according to Fig. 1 in more detail. Reference numeral 501 designates the side of the thrust body 500 facing the gas generator 40; reference numeral 502 designates the side facing the gas generator 40 according to Fig. 1 side of the thrust body 500 facing away from the drive wheel 50 or the side of the thrust body 500 facing the drive wheel 50. The arrow with the reference symbol P symbolizes the thrust direction of the thrust body 500 as soon as it is moved in the direction of the drive wheel 50 by the gas of the gas generator 40.

[0031] In the Fig. 2, the left half of the illustration shows the thrust body 500 in a view from the side; the right half of the illustration in Fig. 2 shows the thrust body 500 in cross section.

[0032] The Fig. 2 shows that the thrust body 500 is equipped with a sealing ring 510, which seals the thrust body 500 against the feed pipe 60 (cf. Fig. 1). In addition, the thrust body 500 has an inertia element 520 in the form of a ring, which - in its Fig. 2 - seals a gas inlet opening 530. Adjoining the gas inlet opening 530 is an inner passage 540, which extends from the gas inlet opening 530 to one or more gas outlet openings 550 on the side 502 of the thrust body 500 facing away from the gas generator. The gas inlet opening 530 and the gas outlet openings 550 of the thrust body 500 are located on different sides of the sealing ring 510 or are separated from one another by the sealing ring 510, as seen along the thrust direction P.

[0033] The gas inlet opening 530 and the inner passage 540 form a venting device of the thrust body 500, which is activated when the thrust body 500 is decelerated.

[0034] In the in the Fig. In the closed position shown in Figure 2, the inertia element 520 closes the gas inlet opening 530, so that a gas flow from the side 501 facing the gas generator 40 to the other side 502 is not possible; because both the sealing ring 510 and the inertia element 520 seal the thrust body 500 from the feed pipe 60.

[0035] If the tensioning process of the tensioner drive 30 is now completed according to Fig. 1 leads to a deceleration of the thrust body 500, the inertial element 520 will continue to move along the thrust direction P due to inertia and will completely or at least partially open the gas inlet opening 530. Due to this relative displacement of the inertial element 520 relative to the gas inlet opening 530, the thrust body 500 becomes leaky, and gas flows through the thrust body 500 and the sealing ring 510. This shows the Fig. 3 in more detail.

[0036] In the Fig. 3 shows the inertial element 520 after it has assumed its release position due to an inertial movement relative to the gas inlet opening 530. The gas inlet opening 530 is exposed, and a gas flow L through the gas inlet opening 530 and through the inner passage 540 to the gas outlet opening 550 on the side 502 is possible. In other words, a gas flow L from the side 501 of the thrust body 500 to the side 502 is possible because the inertial element 520 has moved further and released the inner passage 540.

[0037] Since the thrust bodies 70 located in front of the thrust body 500 are not themselves sealed, the gas from the gas generator can pass through all the thrust bodies after the thrust body 500 becomes leaky, so that the excess pressure in the supply pipe can be relieved via the supply pipe end located in the area of ​​the drive wheel 50. Thus, after the end of the tensioning process, a backward movement of the drive wheel 50 and a backward movement of the thrust bodies 70 and 500 toward the gas generator becomes possible. A backward movement may be necessary, for example, to limit the belt force by means of a belt force limiting device (e.g., in the form of a torsion bar).

[0038] The Fig. 4 shows a further embodiment of a thrust body 500 which is used in the tensioner drive 30 according to Fig. 1 can be used. As with the Fig. 2 and Fig. 3 shows the left half of the Fig. 4 the thrust body 500 in a view from the side, and the right half of the Fig. 4 shows the thrust body 500 in cross section.

[0039] The thrust body 500 has an inertia element 520 in the form of a closure element arranged inside the thrust body 500 or inside the inner passage channel 540. In the Fig. 4, the inertia element 520 closes a gas inlet opening 530 from the inside, which can be brought into gas flow connection with the inner passage 540 and thus with one or more gas outlet openings 550 on the side 502 of the thrust body 500 facing away from the gas generator when the inertia element is moved from the position shown in the Fig. 4 is transferred into a release position.

[0040] At the Fig. In the position of the inertia element 520 shown in Figure 4, the thrust body 500 is sealed off from the feed pipe of the tensioner drive because the sealing ring 510 seals the thrust body 500 radially from the outside and the inertia element 520 arranged inside the through-channel 540 seals the through-channel 540 radially from the inside.

[0041] If the thrust body 500 is decelerated at the end of the tensioning process of the tensioner drive, the inertial element 520 will continue to move along the thrust direction P in the through-channel 540 due to inertia and will release the gas inlet opening 530. As soon as the inertial element 520 has reached the front end of the inner through-channel 540, a gas flow L through the gas inlet opening 530 and the inner through-channel 540 to the gas outlet opening 550 becomes possible, as will be described in more detail in the Fig. 5 is shown.

[0042] In the Fig. 5 shows that the inner passage 540 is radially widened towards the end or in the area of ​​the gas outlet opening 550, so that the gas flow L through the passage 540 becomes possible as soon as the inertia element 520 has reached this radially widened section. Fig. The position of the inertia element 520 shown in Figure 5 therefore represents the release position of the inertia element 520, in which the sealing effect of the thrust body 500 is deactivated.

[0043] The Fig. 6 shows an embodiment of an inertia element 520 which, in the embodiment according to the Fig. 4 and Fig. 5 can be inserted inside the through-channel 540. The inertia element 520 according to Fig. 6 is three-legged and has three legs 521, 522 and 523, which extend radially outward from the center M of the inertia element 520. The outer surfaces 521a, 522a and 523a of the three legs 521, 522 and 523 can cover three gas inlet openings in the closed position of the inertia element 520 and thus close an associated passage in the thrust body. In other words, the inertia element 520 is according to Fig. 6 is therefore suitable or designed to close a total of three gas inlet openings in the closed position.

[0044] The arrangement of the three legs 521, 522 and 523 is preferably rotationally symmetrical with respect to the center point M; in a corresponding manner, the arrangement of the associated gas inlet openings is also preferably arranged in a correspondingly rotationally symmetrical manner.

[0045] The Fig. 7 shows an embodiment of a cup-shaped inertia element 520, which is held in its closed position, in which it closes a gas inlet opening 530 of the thrust body 500, by means of a shearable holding device 600. The shearable holding device 600 can be formed, for example, by a shear pin that is attached to the cup-shaped inertia element 520 and engages, for example, in the gas inlet opening 530.

[0046] If the inertial element 520 wishes to move further forward along the thrust direction P and relative to the gas inlet opening 530 due to inertia towards the end of the tensioning process or when the thrust body 500 is decelerated, the shearable holding device 600 will shear off and release the inertial element 520 so that it can move forward along the thrust direction P.

[0047] In the embodiment according to Fig. 7 also acts together with the inertia element 520 with a spring device 700, the spring force F of which is aligned in the thrust direction P and thus supports the forward movement of the inertia element 520 in the thrust direction P after the release device 600 has been sheared off.

[0048] The spring force F of the spring device 700 is selected such that in the rest state of the thrust body 500 it cannot destroy or shear off the releasable holding device 600 on its own.

[0049] The Fig. 8 shows a further exemplary embodiment of a pot-shaped inertia element 520 which is provided with a releasable holding device 600 and with a spring device 700.

[0050] In contrast to the exemplary embodiment according to Fig. 7, the shearable holding device 600 is arranged in such a way that shearing of the shearable holding device 600 does not only occur when the thrust body 500 is decelerated towards the end of the tensioning process, but already when the thrust body 500 is accelerated in the starting phase of the tensioning process.

[0051] When the tightening process begins, the inertia of the inertia element 520 will initially lag behind the rest of the thrust body 500, so that the shearable holding device 600 will be subjected to significant mechanical stress and will shear off. As soon as the holding device 600 is sheared off, the inertia element 520 will continue to lag behind the rest of the thrust body 500 due to inertia—due to the forward acceleration of the thrust body 500—and will initially move in the opposite direction to the thrust direction P. The sealing effect of the gas inlet opening 530 initially remains unaffected by this relative movement.

[0052] Towards the end of the tensioning process or when braking the thrust body 500, the inertial element 520 will continue to move forward along the thrust direction P, as already described in connection with the embodiments according to the Fig. 2 to 7. The inertia element 520 will thereby release the gas inlet opening 530, so that a gas flow through the gas inlet opening 530 and the inner passage 540 to a Fig. 8 not shown gas outlet opening of the thrust body 500 becomes possible.

[0053] In the embodiment according to Fig. 8, a spring device 700 also cooperates with the inertia element 520, the spring force F of which is aligned in the thrust direction P and will support the forward movement of the inertia element 520 in the thrust direction P.

[0054] The shearable holding device 600 is in the embodiment according to Fig. 8 - In contrast to the embodiment according to Fig. 7 - not coupled to the gas inlet opening 530, but instead to an additional opening which is in the Fig. 8 and is denoted by reference numeral 710. List of reference numerals 10 Belt roller 20 Belt spindle 30 Tightening drive 35 Mass inertia clutch 40 Gas generator 50 Drive wheel 51 Holding cap 52 Holding plate 60 Feed pipe 70 Piston 80 Spring 100 Receiving bowl 110 Receiving container 500 Piston, spring force 501 facing side 502 opposite side 510 Sealing ring 520 Inertia element 521 Leg 521a Outer surface 522 Leg 522a Outer surface 523 Leg 523a Outer surface 530 Gas inlet opening 540 Inner passage channel 550 Gas outlet openings 600 Holding device 700 Spring device 710 Additional opening F Spring force L Gas flow M Center; Midpoint P Arrow P Pushing direction

Claims

[1] Tensioner drive (30) for a safety belt device with: - a gas generator (40), - a drive wheel (50) and - a feed pipe (60) connecting the gas generator (40) and the drive wheel (50), - wherein at least one thrust body (70, 500) is present in the feed pipe (60), which is accelerated after triggering of the gas generator (40) and drives the drive wheel (50), - wherein the or at least one of the thrust bodies (500) seals the feed pipe (60) during the acceleration phase of the thrust body (500) and is equipped with a venting device which is closed by an inertia element (520) of the thrust body (500) during the acceleration phase of the thrust body (500), and - wherein the inertia element (520) is arranged such that, when the thrust body (500) is decelerated, it is displaced relative to the venting device due to inertia and enables a flow of the gas from the gas generator (40) through the thrust body (500) or past the thrust body (500) and through the section of the feed pipe (60) located in front of the thrust body (500) in the direction of thrust in the direction of thrust, characterized by , that - the inertia element (520) is formed by a closure element arranged inside the thrust body (500), which closes at least one gas inlet opening (530) and at least one through-channel (540) in the thrust body (500) during the acceleration phase of the thrust body (500), - the closure element is displaced relative to the gas inlet opening (530) due to inertia when the thrust body (500) is decelerated, in particular in the final phase of the tightening process or at the end of the tightening process, and thereby enables a flow of the gas of the gas generator (40) through the at least one gas inlet opening (530) and the at least one through-channel (540), - the thrust body (500) has two or more gas inlet openings which are closed by the closure element during the acceleration phase of the thrust body (500), and - the closure element has in cross-section at least two radially outwardly pointing legs (521, 522, 523), which - in the closed position of the closure element with their radially outer outer surface (521a, 522a, 523a) each seal one of the gas inlet openings. [2] Tensioner drive (30) according to claim 1, characterized bythat the gas inlet openings and the radially outward-pointing legs (521, 522, 523) are each arranged rotationally symmetrically. [3] Tensioner drive (30) according to one of the preceding claims, characterized by , that - the venting device has a gas inlet opening (530) and a passage channel (540) through the thrust body (500) or is formed by these and - the inertia element (520) is arranged such that when the thrust body (500) is decelerated it moves relative to the gas inlet opening (530) and thereby releases the through-channel (540) through the thrust body (500), so that the gas of the gas generator (40) can flow through the thrust body (500) in the direction of the drive wheel (50). [4] Tensioner drive (30) according to one of the preceding claims, characterized by , that - an inertia element (520) is arranged on the outside of the thrust body (500) and closes at least one gas inlet opening (530) to at least one through-channel (540) in the thrust body (500) from the outside during the acceleration phase of the thrust body (500) and - the inertia element (520) arranged on the outside of the thrust body is displaced relative to the gas inlet opening (530) due to inertia when the thrust body (500) is decelerated, in particular in the final phase of the tensioning process or at the end of the tensioning process, and thereby enables a flow of the gas of the gas generator (40) through the gas inlet opening (530) and the through-channel (540) in the direction of the drive wheel (50). [5] Tensioner drive (30) according to one of the preceding claims, characterized bythat a return prevention device is provided which prevents a return movement of the inertia element (500, 520) arranged inside or outside and a reclosing of the venting device. [6] Tensioner drive (30) according to one of the preceding claims, characterized by that the inertia element (500, 520) arranged inside or outside is held in its position releasing the venting device by positive locking and / or non-positive locking after its relative movement. [7] Tensioner drive (30) according to one of the preceding claims, characterized by that the inertia element (500, 520) arranged inside or outside is held in a predetermined position by means of a shearable holding device (600) before the gas generator (40) is triggered. [8] Tensioner drive (30) according to one of the preceding claims, characterized by , that - a plurality of thrust bodies are present in the feed pipe (60), one of which is equipped with the venting device and seals the feed pipe (60) during the acceleration phase of the thrust body (500), - the thrust bodies (70) located in front of this sealing thrust body (500) are smaller than the inner diameter of the feed pipe (60) and do not seal the feed pipe (60) itself, and - after the inertia element (520) has been moved and after the venting device of the thrust body (500) which is then no longer sealing has been opened, the gas flow is enabled through this thrust body (500) or past this thrust body (500) and past the thrust bodies (70) located in front of it in the direction of the drive wheel (50).

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