Tensioner drive for a belt retractor

Abstract

The invention relates, inter alia, to a tensioner drive (1) for a belt retractor (3) with a feed pipe (10) and a gas generator (20) attached to one end (11) of the feed pipe (10), which gas generator feeds gas (G) into the feed pipe (10) after ignition, wherein the feed pipe (10) is provided with a stop region (13) at or in the region of its other end (12), a drive body (40) and a pusher element (50) which pushes the drive body (40) after ignition of the gas generator (20) are arranged downstream of the gas generator (20), as seen in the gas flow direction, and the stop region (13) is dimensioned such that the drive body (40) can pass through the stop region (13), but the pusher element (50) is stopped.According to the invention, in the stopped position of the thrust element (50) at least one gas flow channel (G50) close to the thrust element remains between the thrust element and the inner wall of the feed pipe (10), through which gas flow channel the gas (G) of the gas generator (20) can pass through the stopped thrust element (50), and a sealing element (60) is arranged in front of the thrust element (50) as seen in the gas flow direction and thus reaches the stop region (13) in front of the thrust element (50), seals the feed pipe (10) in terms of gas flow before reaching the stop region (13) and becomes non-sealing upon penetration into the stop region (13) and allows the gas (G) of the gas generator (20) to pass through.

Description

[0001] The invention relates to a tensioner drive for a belt retractor, wherein the tensioner drive is equipped with a supply tube and a gas generator attached to one end of the supply tube, which, when ignited, feeds gas into the supply tube. Such a tensioner drive is known, for example, from US Patent 9,555,768 B2.

[0002] In the previously known pretensioner drive, the supply tube is provided with a stop zone near its other end. Following the gas generator—as seen in the direction of gas flow—are a drive body and a thrust element, which pushes the drive body after the gas generator is ignited. The stop zone is dimensioned such that the drive body can pass through the stop zone, but the thrust element is stopped. In the previously known pretensioner drive, the supply tube remains pressurized even after the pretensioning process is completed.

[0003] The invention is based on the object of further developing a tensioner drive of the type specified at the beginning.

[0004] This object is achieved according to the invention by a tensioner drive having the features according to claim 1. Advantageous embodiments of the belt retractor according to the invention are specified in subclaims.

[0005] According to the invention, it is then provided that in the stopped position of the thrust element between the thrust element and the inner wall of the feed pipe at least one gas flow channel close to the thrust element remains, through which the gas of the gas generator can pass through the stopped thrust element, and a sealing element in front of the thrust element reaches the stop area, seals the feed pipe in terms of gas flow before reaching the stop area and becomes non-sealing upon penetration into the stop area and allows the gas of the gas generator to pass through.

[0006] A key advantage of the tensioner drive according to the invention is that the thrust element is retained in the supply pipe by the stop region and cannot leave the supply pipe. However, despite the retention of the thrust element, unlike, for example, the previously mentioned tensioner drive, the design according to the invention ensures that the supply pipe is depressurized after the thrust element stops. This is because the sealing element is located upstream of the thrust element in the gas flow direction and loses its sealing effect upon entering or passing through the stop region.

[0007] In a design of the tensioner drive considered advantageous, the cross-section of the supply pipe in the stop region is radially smaller in at least one cross-sectional area than the cross-section upstream of the stop region. The at least one radially smaller cross-sectional area can serve to stop the thrust element; moreover, the at least one radially smaller cross-sectional area can cause deformation, for example, irreversible deformation or total or partial destruction of the sealing element.

[0008] The radially smaller cross-sectional area(s) can be formed, for example, by mechanically machining the supply pipe by pressing or tapering it in sections. In such a case, the radially smaller cross-sectional area(s) can also be referred to as mechanically tapered cross-sectional areas. The radially smaller cross-sectional area(s) can, for example, form beads.

[0009] It is advantageous if at least two radially smaller cross-sectional areas are present. The radially smaller cross-sectional areas are preferably arranged rotationally symmetrically.

[0010] It can also advantageously be provided that the cross-section of the supply pipe in the stop region is radially larger in at least one cross-sectional area than the cross-section upstream of the stop region. The at least one radially larger cross-sectional area can additionally serve to guide a gas flow tangentially past the sealing element, thereby further supporting the sealing element's leak-tightness. The at least one radially larger cross-sectional area can also radially outwardly delimit the gas flow channel, or at least a portion of it, of the at least one gas flow channel near the thrust element.

[0011] The radially larger cross-sectional area(s) can be formed, for example, by machining the supply pipe, in which it is mechanically expanded in sections. In such a case, the radially larger cross-sectional area(s) can also be referred to as mechanically expanded cross-sectional areas.

[0012] It is advantageous if at least two radially larger cross-sectional areas are present. The radially larger cross-sectional areas are preferably arranged rotationally symmetrically.

[0013] It is considered advantageous if the gas from the gas generator can pass through the sealing element and exit the supply tube through at least one gas flow channel near the sealing element, which is delimited by the outer wall of the sealing element and the inner wall of the supply tube in the stop region. For example, the aforementioned radially larger cross-sectional area can radially delimit the gas flow channel near the sealing element toward the outside.

[0014] When the thrust element is stopped, the sealing element can remain entirely or at least partially in the stop area or be pushed through it.

[0015] If the sealing element is pushed by the pushing element completely or at least partially through the stop region, it is considered advantageous if the cross section of the feed tube in the region between the stop region and the other end of the feed tube is shaped differently than the cross section of the sealing element after the latter has been pressed through the stop region, whereby at least one gas flow channel is formed near the sealing element, which is delimited by the outer wall of the sealing element and the inner wall of the feed tube in the region between the stop region and the other end of the feed tube and through which the gas from the gas generator can pass in the direction of the other end of the feed tube.

[0016] As already mentioned, the sealing element's sealing function is destroyed by a change in shape, preferably irreversibly, upon penetration into the stop zone. It is advantageous if a radially outer section of the sealing element is sheared off upon penetration into the stop zone.

[0017] If the cross-section of the sealing element has been reduced due to such an irreversible change in the sealing element in the stop area, the cross-section of the supply pipe behind the stop area and the cross-section of the supply pipe in front of the stop area may be identical; otherwise, or generally, the cross-section of the supply pipe behind the stop area may be larger than the cross-section of the supply pipe in front of the stop area.

[0018] The drive body is preferably smaller than the cross-section of the feed pipe, at least after passing the stop area, and thus has no sealing effect.

[0019] The thrust body is or preferably becomes free of sealing effect at least when the stop area is reached.

[0020] The sealing element can be attached to the drive body or formed as a single piece; alternatively, the sealing element can be arranged as a separate component between the drive body and the thrust body.

[0021] In a further embodiment considered advantageous, it is provided that a non-sealing spacer body is arranged between the sealing element and the drive body.

[0022] In the latter embodiment, it is advantageous if the longitudinal extension of the spacer body—as seen in the longitudinal direction of the feed tube—is dimensioned so large that, when the thrust element is stopped, the drive body is at least pushed out of the stop area of ​​the feed tube. Particularly preferably, the spacer body pushes the drive body completely out of the drive tube.

[0023] The sealing element and the spacer body are preferably coupled to one another, in particular connected to one another by a clip connection.

[0024] It is also particularly advantageous, in particular to avoid rattling noises in the basic state before the tensioner drive is triggered, if a non-sealing, axially resilient spring element is arranged between the thrust element and the gas generator, the cross section of which is shaped such that between the inner wall of the feed tube and the outer wall of the spring element there is at least one gas flow channel close to the spring element, through which the gas can pass the spring element in the direction of the other end of the feed tube.

[0025] The spring element is preferably formed by a one-piece plastic body.

[0026] The drive body is preferably a deformable drive rod.

[0027] The thrust element is preferably a ball.

[0028] In the stopped position of the thrust element, the gas from the gas generator can preferably leave the supply pipe at its other end, so that the supply pipe is depressurized after the tensioning process is completed.

[0029] The invention also relates to a belt retractor with a tensioner drive. According to the invention, the tensioner drive is configured as described above, and the drive wheel of the tensioner drive is directly or indirectly connected to a belt spool of the belt retractor and—driven by a movement of the drive body past the drive wheel—can be set into a rotational movement along a direction of rotation corresponding to the winding direction of the belt retractor.

[0030] The invention is explained in more detail below using exemplary embodiments, which show, for example: Fig. 1 Components of a first embodiment of a tensioner drive according to the invention, with which a belt reel of a belt retractor comprising the tensioner drive can be driven in the belt winding direction, Fig. 2a-2c advantageous embodiments of the cross section of a feed pipe of the tensioner drive according to Fig. 1 in a stop area, Fig. 3 an advantageous embodiment of a spring element of the tensioner drive according to Fig. 1 and Fig. 4 Components of a second embodiment of a tensioner drive according to the invention.

[0031] For the sake of clarity, the same reference symbols are always used in the figures for identical or comparable components.

[0032] The Fig. 1 shows components of a first embodiment of a tensioner drive 1 according to the invention, with which a belt reel 2 of a belt retractor 3 comprising the tensioner drive 1 can be driven in the belt winding direction.

[0033] The tensioner drive 1 comprises a supply tube 10, a gas generator 20 attached to one end 11 of the supply tube 10, a drive wheel 30 and a drive body 40 which is located at least partially in the supply tube 10 before the ignition of the gas generator 20 and which drives the drive wheel 30 after the ignition of the gas generator 20.

[0034] In the embodiment according to Fig. 1, the drive body 40 is a single piece and is formed by a deformable drive rod; alternatively, the drive body 40 can be multi-piece and formed by two or more drive elements that are connected or unconnected to one another. A multi-piece drive body 40 can, for example, be formed by a plurality of loosely adjacent drive balls.

[0035] The cross section of the drive body 40 is smaller than the cross section of the feed pipe 10, so that the drive body 40 is free of sealing effects from the outset.

[0036] In the representation according to Fig. 1 shows the state of the tensioner drive 1 after the end of the tensioning process, so that the drive body 40 has largely left the feed pipe 10 and passed the drive wheel 30.

[0037] The feed tube 10 is provided in the region of its other end 12 with a stop region 13 which is dimensioned such that the drive body 40 can pass through the stop region 13, but a thrust element 50 pushing the drive body 40 after ignition of the gas generator 20 is stopped. The thrust element 50 is in the embodiment according to Fig. 1 spherical.

[0038] The cross section of the thrust element 50 is smaller than the cross section of the feed pipe 10, so that the thrust element 50 is free of sealing effects from the outset.

[0039] The Fig. 1 also shows that in the region of the end 41 of the drive body 40 facing the gas generator 20 in terms of gas flow, a sealing element 60 is placed on the drive body 40. The sealing element 60, together with the drive body 40, is pushed by the thrust element 50 into the stop region 13 or even through it completely or only partially. In the embodiment according to Fig. 1, the sealing element 60 and the end 41 of the drive body 40 facing the gas generator 20 in terms of gas flow remain completely within the stop region 13. Alternatively, the sealing element 60 can be pushed completely or at least partially out of the stop region or through it.

[0040] The sealing element 60 serves to seal the supply pipe 10 in terms of gas flow before reaching the stop area 13, so that the gas G from the gas generator 20 cannot pass through the sealing element 60 in the gas flow direction. Upon penetration into the stop area 13, the sealing element 60 loses its sealing function and allows the gas G from the gas generator 20 to pass through. The loss of the sealing function is based on the design, for example, the shape of the inner wall area, of the stop area 13.

[0041] Thus, in the embodiment according to Fig. 1, the gas G of the gas generator 20 flows through the sealing element 60 through gas flow channels G60 near the sealing element (see Fig. 2a and Fig. 2b), which are each delimited by the outer wall of the sealing element 60 and the inner wall of the feed pipe 10 in the stop area 13, and can exit the feed pipe 10. For this purpose, the cross-section of the feed pipe 10 in the stop area 13 is larger in some sections than the cross-section of the sealing element 60.

[0042] The Fig. 2a shows a first exemplary embodiment of the gas flow channels G60 near the sealing element, which is based on a partial radial widening of the feed pipe 10 in radially widened cross-sectional areas RA10 of the feed pipe 10. Specifically, in the embodiment according to Fig. 2a, it is provided that in the area of ​​the gas flow channels G60 or in the area of ​​the radially widened cross-sectional areas RA10, the cross section of the feed pipe 10 is partially radially larger than the cross section of the feed pipe 10 in the gas flow direction upstream of the stop area 13 in order to form the gas flow channels G60 close to the sealing element, and partially in radially tapered cross-sectional areas RV10 is radially smaller than the cross section of the feed pipe 10 upstream of the stop area 13 in order to form a stop for the thrust element 50, which the thrust element 50 cannot pass.

[0043] The radially larger or radially expanded cross-sectional areas RA10 of the feed pipe 10 can be produced by expanding with an expanding tool. The radially smaller or radially tapered cross-sectional areas RV10 of the feed pipe 10 can be produced by compression.

[0044] The Fig. 2b shows a second exemplary embodiment of the stop region 13 without radially larger or radially expanded cross-sectional areas RA10; instead of the radially larger or radially expanded cross-sectional areas RA10, undeformed cross-sectional areas RN10 are present, in which the feed pipe 10 has the same inner diameter as the cross section of the feed pipe 10 upstream of the stop region 13.

[0045] The existence of the sealing element-near gas flow channels G60 is based on the Fig. 2b that the sealing function of the sealing element 60 is irreversibly destroyed by a change in shape when it penetrates the stop area 13. Such irreversible destruction can, for example, be caused by reshaping or compressing the sealing element (as in the Fig. 2b) and / or by shearing off partial sections. Shearing off can be caused by the radially smaller or tapered cross-sectional areas RV10 of the feed pipe 10, which also serve to stop the thrust element 50.

[0046] In the embodiment according to Fig. 2b, the radially smaller or radially tapered cross-sectional areas RV10 deform the sealing element 60 such that it no longer has a sealing function even in the undeformed cross-sectional areas RN10 of the feed pipe 10, because the sealing element 60 no longer has contact with the inner wall of the feed pipe 10 in the undeformed cross-sectional areas RN10. In the undeformed cross-sectional areas RN10 of the feed pipe 10, the sealing element preferably has the same inner diameter as the cross section of the feed pipe 10 upstream of the stop area 13.

[0047] An irreversible change in shape of the sealing element 60 is particularly advantageous when the sealing element 60 is pushed out of the stop region 13 after the end of the tightening process and the pipe section of the feed pipe in the pipe region behind the stop region 13, i.e., between the stop region 13 and the other end 12 of the feed pipe 10, has the same cross-section (or the same size and shape in cross-section) as in the pipe region in front of the stop region 13; because the sealing element 60 should not be able to have a sealing function in the pipe region behind the stop region 13 either.

[0048] The Fig. For comparison, Fig. 2c shows the thrust element 50 when it is in contact with the stop area 13 according to Fig. 2a and 2b, respectively. It can be seen that the radially smaller cross-sectional areas RV10 of the feed pipe 10 stop the thrust element 50, and the gas flow channels G50 near the thrust element are delimited by the radially larger or radially expanded cross-sectional areas RA10 of the feed pipe 10 and the undeformed cross-sectional areas RN10 of the feed pipe 10, respectively.

[0049] Referring again to Fig. 1 shows that a non-sealing, axially resilient spring element 70 is arranged between the thrust element 50 and the gas generator 20. To ensure that the spring element 70 cannot perform a sealing function, its cross-section is shaped such that at least one gas flow channel G70 (see Fig. 3) is present through which the gas G can pass the spring element 70 towards the other end 11 of the supply pipe 10.

[0050] The Fig. 3 shows the spring element 70 according to Fig. 1 in more detail. Radial groove-shaped depressions V70 can be seen, which extend axially over the entire length of the spring element 70 and, together with the inner wall of the supply tube 10, form the aforementioned gas flow channels G70 near the spring element.

[0051] The spring element 70 can be formed by a one-piece plastic body.

[0052] The Fig. 4 shows components of a second embodiment of a tensioner drive 1 according to the invention, with which a belt reel 2 of a belt retractor 3 comprising the tensioner drive 1 can be driven in the belt winding direction.

[0053] The second embodiment according to Fig. 4 corresponds to the first embodiment according to Fig. 1 with two differences, namely, firstly, that the sealing element 60 is not attached or molded onto the drive body 40, but forms a separate part between the drive body 40 and the thrust element 50, and secondly, that a non-sealing spacer body 80 is arranged between the drive body 40 and the sealing element 60.

[0054] The cross-section of the spacer body 80 is smaller than the cross-section of the supply pipe 10, so that the spacer body 80 is free of sealing effects from the outset.

[0055] The longitudinal extension of the spacer body is dimensioned so large - seen in the longitudinal direction of the feed pipe 10 - that when the thrust element 50 is stopped, the drive body 40 is completely pushed out of the stop area 13 of the feed pipe 10.

[0056] The sealing element 60 can also be completely pushed out of the stop area 13 or, as in the Fig. 4, remain entirely or partially in the stop area 13.

[0057] If the sealing element 60 remains partially in the stop area 13, the leakage of the sealing element 60 within the stop area 13 can be caused by the shape of the feed pipe, as described above in connection with the Fig. 2a and Fig. 2b is shown as an example.

[0058] If the sealing element 60 is completely pressed out of the stop area 13, the radially smaller sections have a dual function because they form a stop for the thrust element 50 in order to stop it and cause an irreversible deformation of the sealing element 60, for example by shearing.

[0059] The leakage of the thrust element 50 or the existence of the gas flow channel(s) G50 near the thrust element can be ensured in the absence of radially larger sections in the stop area 13 by selecting the cross section of the thrust element 50 to be correspondingly small and shaping it in such a way that even when the thrust element 50 rests against the stop area 13, cross-sectional areas without overlap still remain despite the radially smaller sections.

[0060] In order to ensure that the sealing element 60 cannot exert a sealing effect behind the stop region 13, the cross section of the feed pipe 10 in the region between the stop region 13 and the other end 12 of the feed pipe 10 can be shaped differently than the cross section of the sealing element 60 after it has been pressed through the stop region 13.

[0061] The different design of the cross sections of the sealing element 60 and the feed pipe 10 behind the stop area 13 can be based - solely on the design of the cross-section of the feed pipe 10 behind the stop area 13, for example by equipping the feed pipe 10 with radially larger sections, as shown in the Fig. 2a in connection with stop area 13, - solely on an irreversible deformation of the sealing element 60 when passing the stop area 13 or - on both of the measures mentioned.

[0062] By means of the measures mentioned, it can be ensured that in the area between the stop area 13 and the other end 11 of the feed pipe 10, at least one gas flow channel G60 remains close to the sealing element, which is delimited by the outer wall of the sealing element 60 and the inner wall of the feed pipe 10 and through which the gas G of the gas generator 20 can pass the sealing element 60 in the direction of the other end 11 of the feed pipe 10.

[0063] The sealing element 60 and the spacer body 80 can be separate parts that rest loosely against each other. Alternatively, it can be provided that the sealing element 60 and the spacer body 80 are coupled to each other, in particular connected by a clip connection. For reasons of clarity, such a clip connection is shown in the Fig. 4 not shown in detail.

[0064] Regarding the remaining design of the second embodiment according to Fig. 4, in particular with regard to the design of the sealing element 60 and the spring element 70, the above statements in connection with the Fig. 1 for the second embodiment according to Fig. 4 shall apply accordingly.

[0065] The two embodiments according to the Fig. 1 and Fig. 4 is that in the stopped position of the thrust element 50, the gas G of the gas generator 20 can leave the feed pipe 10 at its other end 12 and the feed pipe 10 becomes pressure-free because the initially sealing sealing element 60 becomes inoperative and the drive body 40, the thrust element 50 and the spring element 70 have no sealing function from the beginning or even before the start of the tensioning process and before the ignition of the gas generator 20.

[0066] When the gas generator 20 is ignited, the gas G of the gas generator 20 pushes the spring element 70 and the thrust element 50 toward the other end 12 of the feed tube 10, whereby the drive body 40 is pushed out of the feed tube 10 and drives the drive wheel 30 of the tensioner drive 1. The drive wheel 30 is directly or indirectly connected to the belt spool 2 and—driven by the movement of the drive body 40 past the drive wheel 30—is set in a rotational movement along a direction corresponding to the winding direction of the belt retractor 3.

[0067] Finally, it should be mentioned that the features of all embodiments described above can be combined with each other in any way to form further other embodiments of the invention.

[0068] All features of subclaims can also be combined individually with each of the independent claims, either individually or in any combination with one or more other subclaims, in order to obtain further other embodiments. List of reference symbols 1 tensioner drive 2 belt reels 3 belt retractors 10 Feed pipe 11 End 12 End 13 Stop area 20 gas generator 30 drive wheel 40 drive bodies 41 End of the drive body 50 thrust element 60 sealing element 70 spring element 80 spacers G Gas G50 gas flow channel near the thrust element G60 gas flow channel close to the sealing element G70 spring element-near gas flow channel RA10 radially larger (e.g. expanded) cross-sectional area RN10 radially unchanged cross-sectional area RV10 radially smaller (e.g. tapered) cross-sectional area V70 recesses QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This 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

[0000] US 9,555,768 B2

[0001]

Claims

[1] Tensioner drive (1) for a belt retractor (3) with a feed pipe (10) and a gas generator (20) attached to one end (11) of the feed pipe (10), which feeds gas (G) into the feed pipe (10) after ignition, wherein - the feed pipe (10) is provided with a stop area (13) at or in the region of its other end (12), - the gas generator (20) - seen in the gas flow direction of the gas (G) - is followed by a drive body (40) and a thrust element (50) which pushes the drive body (40) after the ignition of the gas generator (20), and - the stop area (13) is dimensioned such that the drive body (40) can pass the stop area (13), but the thrust element (50) is stopped, characterized by , that - in the stopped position of the thrust element (50) between the thrust element and the inner wall of the supply pipe (10), at least one gas flow channel (G50) close to the thrust element remains, through which the gas (G) of the gas generator (20) can pass the stopped thrust element (50), and - a sealing element (60) is arranged in front of the thrust element (50) as seen in the gas flow direction and thus reaches the stop area (13) in front of the thrust element (50), seals the feed pipe (10) in terms of gas flow before reaching the stop area (13) and loses its sealing function upon penetration into the stop area (13) and allows the gas (G) of the gas generator (20) to pass through. [2] Tensioner drive (1) according to claim 1, characterized by that the cross section of the feed pipe (10) in the stop region (13) is radially smaller in at least one cross-sectional region (RV10) than the cross section - seen in the gas flow direction - in front of the stop region (13). [3] Tensioner drive (1) according to one of the preceding claims, characterized by , that - the gas (G) of the gas generator (20) can pass through the sealing element (60) through at least one gas flow channel (G60) close to the sealing element, which is delimited by the outer wall of the sealing element (60) and the inner wall of the feed pipe (10) in the stop region (13), and can leave the feed pipe (10). [4] Tensioner drive (1) according to one of the preceding claims 2 to 3, characterized by that the cross section of the feed pipe (10) in the stop region (13) is radially widened in at least one cross-sectional region (RA10) and the radially widened cross-sectional region (RA10) radially outwards delimits the at least one gas flow channel (G50) near the thrust element and / or the at least one gas flow channel (G60) near the sealing element. [5] Tensioner drive (1) according to one of the preceding claims, characterized bythat before or upon reaching its stopped position, the pushing element (50) has pushed the sealing element (60) at least partially through the stop region (13). [6] Tensioner drive (1) according to claim 5, characterized by , that - the cross-section of the feed pipe (10) in the region between the stop region (13) and the other end (12) of the feed pipe (10) is shaped differently than the cross-section of the sealing element (60) after it has been pressed through the stop region (13), - whereby at least one gas flow channel (G60) close to the sealing element is formed, which is delimited by the outer wall of the sealing element (60) and the inner wall of the feed pipe (10) in the region between the stop region (13) and the other end of the feed pipe (10) and through which the gas (G) of the gas generator (20) can pass in the direction of the other end of the feed pipe (10). [7] Tensioner drive (1) according to one of the preceding claims, characterized by that the sealing function of the sealing element (60) is irreversibly destroyed by a change in shape when it penetrates into the stop area (13). [8] Tensioner drive (1) according to one of the preceding claims, characterized by that a radially outer portion of the sealing element (60) is sheared off upon penetration into the stop region (13). [9] Tensioner drive (1) according to one of the preceding claims, characterized by that the sealing element (60) is attached or formed on the drive body (40). [10] Tensioner drive (1) according to one of the preceding claims 1 to 8, characterized by that a non-sealing spacer body (80) is arranged between the sealing element (60) and the drive body (40). [11] Tensioner drive (1) according to claim 10, characterized bythat the longitudinal extent of the spacer body (80) - seen in the longitudinal direction of the feed pipe (10) - is dimensioned so large that when the thrust element (50) is stopped, the drive body (40) is pressed out at least from the stop region (13) of the feed pipe (10), preferably completely from the feed pipe (10). [12] Tensioner drive (1) according to one of the preceding claims 10 to 11, characterized by that the sealing element (60) and the spacer body (80) are coupled to one another, in particular connected to one another by a clip connection. [13] Tensioner drive (1) according to one of the preceding claims, characterized bythat between the thrust element (50) and the gas generator (20) there is arranged a non-sealing, axially resilient spring element (70), the cross-section of which is shaped such that between the inner wall of the feed tube (10) and the outer wall of the spring element (70) there is at least one gas flow channel (G70) close to the spring element, through which the gas (G) can pass the spring element (70) in the direction of the other end (12) of the feed tube (10). [14] Tensioner drive (1) according to claim 13, characterized by that the spring element (70) is formed by a one-piece plastic body. [15] Tensioner drive (1) according to one of the preceding claims, characterized by that in the stopped position of the thrust element (50) the gas (G) of the gas generator (20) can leave the feed pipe (10) at its other end (12) and the feed pipe (10) becomes pressure-free. [16] Belt retractor (3) with tensioner drive, characterized by , that - the tensioner drive is a tensioner drive (1) according to one of the preceding claims and - the drive wheel (30) of the tensioner drive (1) is directly or indirectly connected to a belt reel (2) of the belt retractor (3) and - driven by a movement of the drive body (40) past the drive wheel (30) - can be set into a rotational movement along a direction of rotation corresponding to the winding direction of the belt retractor (3).

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