CN108791178B

CN108791178B - Pyrotechnic pre-tensioning mechanism fixing structure and safety belt retractor

Info

Publication number: CN108791178B
Application number: CN201710286883.0A
Authority: CN
Inventors: 李鑫
Original assignee: BYD Co Ltd
Current assignee: BYD Co Ltd
Priority date: 2017-04-27
Filing date: 2017-04-27
Publication date: 2020-06-19
Anticipated expiration: 2037-04-27
Also published as: CN108791178A

Abstract

The invention provides a fixing structure of a pyrotechnic pre-tensioning mechanism and a safety belt retractor. During assembly, the fixed elastic sheet is clamped on the outer peripheral surface of the cylinder, the cylinder extrudes the fixed elastic sheet to enable the semi-ring portion to slightly deform in the process, and then the fixed elastic sheet is clamped on the outer peripheral surface of the cylinder body through deformation of the semi-ring portion. Then, withhold spacing apron on fixed shell fragment, the bulge of the fixed shell fragment of extrusion, the bulge can extrude and hold in the recess with deforming, then fix the mount pad of spacing apron on a lateral wall of frame so that the cylinder limiting plate will fix shell fragment and cylinder and compress tightly on a lateral wall of frame to the direction that is close to the frame integratively. The bulge can be accommodated in the groove in a pressing and deforming mode to limit deflection of the cylinder, and the situation that the cylinder is not subjected to deflection looseness caused by conditions such as bumping, impacting and vibrating is guaranteed.

Description

Pyrotechnic pre-tensioning mechanism fixing structure and safety belt retractor

Technical Field

The invention belongs to the technical field of vehicle seat belt devices, and particularly relates to a fixing structure of a pyrotechnic pretensioning mechanism and a belt retractor.

Background

A vehicle seat belt apparatus is an important protection apparatus in a vehicle, and restrains a passenger from bouncing up from a seat in the event of a collision or sudden braking of the vehicle. Which in turn is the most important component in a vehicle seat belt arrangement. The safety belt retractor carries out retraction of the woven belt through rotation of the belt winding drum, and therefore triggering and disconnection actions of the safety belt restraint effect are achieved.

Since a webbing is relatively loosely attached to a human body after a seat belt (hereinafter, referred to as a webbing) is fastened by a vehicle occupant, in order to reduce the amount of webbing that is pulled out in an emergency (for example, a frontal collision) of the vehicle, a conventional mechanical sensor lock mechanism is generally provided in a seatbelt retractor.

The common technologies of safety belt coiler's preloading device are two kinds, one kind for the pyrotechnic composition pretension mechanism, including rack and pinion formula and ball gear formula, the technique is very mature, uses comparatively commonly. The other is a motor pre-tensioning mechanism, belongs to the active and passive crossing technology, and is not used in large quantity.

The working principle of the pyrotechnic pre-tensioning mechanism is as follows: under normal conditions, when the acceleration of pulling out the mesh belt or the acceleration of the vehicle body exceeds the acceleration set by the mechanical sensor, the mechanical sensing type locking mechanism locks the mesh belt drum to prevent the mesh belt from being pulled out, in the process, the pyrotechnic type pre-tensioning mechanism is not started and does not participate, when the vehicle has an emergency condition (such as forward collision), the pyrotechnic type pre-tensioning mechanism is started instantly, the gas generating device generates a large amount of gas to push the rack to move along the direction of the cylinder, the rack can be meshed with the gear in the forward direction, meanwhile, the friction plate connected with the gear is driven to rotate, the friction plate can be connected with the mesh belt drum assembly into a whole through the actions of extrusion friction and the like, and then the rack drives the mesh belt drum to rotate towards the direction of winding and recovering the mesh belt under the pushing of the gas, so that the rewinding of the mesh belt is realized, and the gap between a passenger and the mesh belt and the seat is eliminated, thereby ensuring the safety of the passengers.

During the process of pre-tightening fireworks, a large amount of gas generated by explosion of a gas generator is sealed in a cylinder, so that extremely high pressure is formed, the pressure pushes a rack to rapidly move along the direction of the cylinder, and finally the stop motion is limited by a stop block on the rack.

In order to solve the problem, the existing solution is to add a fixing mechanism to the cylinder separately, and to keep the cylinder on the main structure (such as a frame) of the seat belt retractor, so as to prevent the cylinder from loosening and affecting the pre-tightening function.

The first one is that two claws formed by a spring sheet are buckled on a frame to press a cylinder; the second is that a spring plate is pressed on the cylinder, two screws are used to fix the spring plate on the frame, a bulge is arranged on the inner surface of the spring plate, and the bulge presses the outer surface of the cylinder, thereby realizing the effect of fixing the cylinder.

In the second scheme, a raised feature is fixed and arranged by using a screw, the phenomenon of difficult positioning can easily occur in assembly, meanwhile, the structure needs to occupy a larger space to accommodate parts and is convenient to assemble, and in addition, the scheme has higher cost. The first scheme compares the second scheme, fix the cylinder to the frame through two jack catch locks on the shell fragment, the screw has been omitted, but the shared space of shell fragment needs the grow, and the shell fragment is because the press surface is little in the assembling process, the deflection is big, and the direction of deformation is not identical at the assembling process with the direction of pressing, the jack catch is fixed on the frame simultaneously, its fixed strength is not enough to some extent than the screw, because vibration, reasons such as jolt, very easily appear jack catch roll-off frame and lead to the not hard up phenomenon of cylinder at pretension in-process or normal loading state. Moreover, both of these solutions have a drawback: only a fixation perpendicular to the frame face is provided. However, the mounting position of the actual cylinder in the seatbelt retractor and the mounting position of the seatbelt retractor in the passenger compartment of the vehicle are often inclined at a certain angle, so that the cylinder may be greatly deflected during long-term vibration and bump.

Considering the safety belt retractor because more and more mechanism development and addition, the space on the main structure has been tense gradually, has not had very big consecutive space to realize the fixed of cylinder again, simultaneously because most cylinders use the circular steel pipe of price/performance ratio high to make, there is the problem that is difficult to assemble and easily takes place to deflect with simple nut is fixed and jack catch lock.

Disclosure of Invention

In order to solve the technical problems that in the fixing structure of the existing pyrotechnic pre-tensioning mechanism, because the cylinder is made of a round steel pipe, the nut is simple to fix, the clamping jaws are buckled, the assembly is difficult, and the deflection is easy to occur, the embodiment of the invention provides the fixing structure of the pyrotechnic pre-tensioning mechanism and a safety belt retractor.

In order to solve the above technical problems, in one aspect, an embodiment of the present invention provides a fixing structure of a pyrotechnic pre-tensioning mechanism, including a frame, a cylinder, a fixing elastic sheet, and a limiting cover plate, where the cylinder is a circular tube component, the fixing elastic sheet includes a semi-ring portion and at least one protrusion portion formed on the semi-ring portion, the limiting cover plate includes a clutch limiting plate, a cylinder limiting plate connected to one side of the clutch limiting plate, and a mounting seat disposed at an edge position of the limiting cover plate, a cambered surface is disposed on a side surface of the cylinder limiting plate facing the fixing elastic sheet, at least one groove is disposed on the cambered surface, the fixing elastic sheet is clamped on an outer circumferential surface of the cylinder through deformation of the semi-ring portion, and the mounting seat is fixed on a sidewall of the frame so that the cylinder limiting plate presses the fixing elastic sheet and the cylinder integrally against a sidewall of the frame in a direction close to the frame, the projection is compressively deformably received in the groove to restrict deflection of the cylinder.

Optionally, the half ring portion includes a plurality of incomplete arc plates, the protruding portion is connected between two adjacent incomplete arc plates, and the plurality of incomplete arc plates and the arc surface are spaced from each other.

Optionally, the protruding portion is provided with a plurality of protruding portions, the protruding portions are distributed on the same circumference at equal intervals, the protruding portions protrude in the radial direction of the circumference where the protruding portions are located, and the length direction of the groove is consistent with the axial direction of the cylinder.

Optionally, the half ring portion includes a first clamping plate and a second clamping plate formed at two ends of the half ring portion, the first clamping plate and the second clamping plate are clamped on the outer circumferential surface of the cylinder in a relatively parallel manner, and a surface of the first clamping plate, which is away from the cylinder, is in contact with a side surface of the cylinder limiting plate, which faces the fixed elastic sheet, of the cylinder limiting plate.

Optionally, the bulge top forms the arc fitting surface, the bottom both ends of bulge are spaced each other in order to be in the bulge inboard forms the extrusion deformation space, the recess has the arc wall, the arc fitting surface is in after the bulge extrusion deformation with the arc wall laminating of recess.

Optionally, a portion of the protrusion below the arcuate mating surface is spaced from the arcuate surface.

Optionally, the mounting seat includes a plurality of support legs, through holes are provided on the support legs, threaded holes are provided on the frame at positions corresponding to the through holes, and the support legs are fixed on the frame by screws passing through the corresponding through holes and threaded holes.

Optionally, the one end of cylinder is formed with the flange, the flange orientation one side of frame is provided with the stopper, correspond to on the lateral wall of frame the position of stopper is provided with the spacing groove, the position that clutch limiting plate and cylinder limiting plate meet is provided with and dodges the groove, the stopper peg graft in the spacing groove, the flange deviates from the part of stopper hold in dodge in the groove.

Optionally, an arc-shaped groove is formed in the frame, a portion, deviating from the cylinder limiting block, of the cylinder is arranged in the arc-shaped groove, and the limiting groove is located at one end of the arc-shaped groove.

According to the fixing structure of the pyrotechnic pre-tensioning mechanism, during assembly, the fixing elastic sheet is clamped on the outer peripheral surface of the cylinder, in the process, the cylinder presses the fixing elastic sheet to enable the half ring portion to deform slightly, and then the fixing elastic sheet is clamped on the outer peripheral surface of the cylinder body through deformation of the half ring portion. Then, withhold spacing apron on fixed shell fragment, the bulge of the fixed shell fragment of extrusion, the bulge can extrude and hold in the recess with deforming, then fix the mount pad of spacing apron on a lateral wall of frame so that the cylinder limiting plate will fix shell fragment and cylinder and compress tightly on a lateral wall of frame to the direction that is close to the frame integratively. From this, fixed shell fragment is as an organic whole with cylinder, fixed shell fragment and spacing apron three connection under the two-way extrusion of spacing apron and cylinder. The bulge can be accommodated in the groove in a pressing and deforming mode to limit deflection of the cylinder, and the situation that the cylinder is not subjected to deflection looseness caused by conditions such as bumping, impacting and vibrating is guaranteed.

On the other hand, the embodiment of the invention also provides a safety belt retractor which comprises the fixing structure of the pyrotechnic pretensioning mechanism.

Drawings

Fig. 1 is a perspective view of a seatbelt retractor according to an embodiment of the present invention;

fig. 2 is an exploded view of a seatbelt retractor provided in an embodiment of the present invention;

fig. 3 is a side view of a seatbelt retractor provided in an embodiment of the present invention;

FIG. 4 is a cross-sectional view taken along the line A-A in FIG. 3;

FIG. 5 is an enlarged view taken at a in FIG. 4;

FIG. 6 is a schematic view of the assembly of the cylinder and the fixing spring plate of the fixing structure of the pyrotechnic pre-tensioning mechanism according to an embodiment of the present invention;

fig. 7 is an assembly diagram of the cylinder, the fixing spring and the limiting cover plate of the fixing structure of the pyrotechnic pre-tensioning mechanism according to an embodiment of the present invention;

FIG. 8 is an enlarged view at b in FIG. 7;

fig. 9 is a perspective view of a retaining cover plate of the pyrotechnic pre-tensioning mechanism provided in accordance with an embodiment of the present invention.

Description of the reference numerals

10. A frame; 101. a limiting groove; 102. an arc-shaped slot;

20. a tape cartridge assembly; 201. a take-up reel; 202. a torsion bar;

30. a pyrotechnic pretensioning mechanism; 301. a gas generator; 302. a cylinder; 3021. a flange; 30211. a limiting block; 303. a piston; 304. a rack; 305. a rack stop block; 306. a gear; 307. a friction plate; 308. fixing the elastic sheet; 3081. a semi-ring portion; 30811. incomplete circular arc plates; 30812. a first clamping plate; 30813. a second clamping plate; 3082. a projection; 30821. an arc-shaped matching surface; 30822. extruding a deformation space; 309. a seal ring;

40. a clutch base;

50. a mechanical sensing type locking mechanism;

60. a limiting cover plate; 601. a clutch limiting plate; 602. a cylinder limiting plate; 603. a mounting seat; 6031. a support leg; 6032. a through hole; 604. a cambered surface; 605. a groove; 606. an avoidance groove;

70. and (4) screws.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to fig. 1 to 9 together, a seatbelt retractor according to an embodiment of the present invention includes a frame 10, a spool assembly 20, a pyrotechnic pre-tensioning mechanism 30, a clutch base 40, a mechanical sensor locking mechanism 50, and a limit cover 60. The take-up reel assembly 20, the pyrotechnic pretensioning mechanism 30, the clutch base 40, the mechanical sensor locking mechanism 50 and the limit cover 60 are all mounted on the frame 10.

The mechanical sensor lock mechanism 50 is not so much related to the present embodiment, and therefore, in fig. 2, the mechanical sensor lock mechanism 50 is not shown.

Between one side wall and the other side wall of the frame 10, a tape reel assembly 20 is supported, i.e., the tape reel assembly 20 is received in the frame 10. The take-up reel assembly 20 includes a take-up reel 201 and a torsion bar 202. The webbing belt is wound in a long belt shape around the winding drum 201. The winding drum 201 winds the webbing by rotating in a winding direction. On the other hand, the take-up drum 201 is rotated in the pull-out direction to pull out the webbing. When the torsion bar 202 is subjected to a torsional load equal to or greater than a predetermined load, torsional deformation may occur. Normally, the torsion bar 202 and the take-up reel 201 rotate integrally.

The pyrotechnic pre-tensioning mechanism 30 is mounted on the outside of one side wall of the frame 10. The pyrotechnic pre-tensioning mechanism 30 includes a gas generator 301, a cylinder 302, a piston 303, a rack 304, a rack stopper 305, a gear 306, a friction plate 307, a fixed spring 308, the clutch base 40, and the like. The gas generator 301 is mounted at the rear end of the cylinder 302. The piston 303 is disposed inside the cylinder 302 and is in sliding sealing contact with the inner wall of the cylinder 302 via a sealing ring 309. A rack 304 is integrally formed or fixed to the front side of the piston 303, a rack stopper 305 is fixed to the rack 304, the rack 304 is in mesh transmission with a gear 306, and the gear 306 is rotatable together with the take-up reel assembly 20 via a friction plate 307. The gear 306, the friction plate 307, and the clutch base 40 constitute a clutch portion of the pyrotechnic pretensioning mechanism 30. The clutch limiting plate 601 is used to limit the clutch portion of the pyrotechnic pretensioning mechanism 30 to a side wall of the frame 10.

Typically, the take-up reel assembly 20 and the gear 306 rotate independently of one another. When an emergency occurs, the gas generator 301 is detonated, a large amount of gas is generated in a sealed space in the cylinder 302, a large pressure is formed, the piston 303 and the rack 304 are further pushed to move along the axial direction of the cylinder 302, the axial movement of the rack 304 drives the gear 306 to rotate, the gear 306 rotates along with the belt winding drum assembly 20 in the winding direction through the friction plate 307, and the winding and the recovery of the woven belt are completed.

In this embodiment, the fixing structure of the pyrotechnic pre-tensioning mechanism includes the frame 10, the cylinder 302, the fixing spring 308, and the limiting cover plate 60. The cylinder 302 is a circular tube member. The cylinder 302 may be machined from round steel tubing.

As shown in fig. 4-9, the fixing spring plate 308 includes a half ring portion 3081 and at least one protrusion portion 3082 formed on the half ring portion 3081, the limit cover plate 60 comprises a clutch limit plate 601, a cylinder limit plate 602 connected to one side of the clutch limit plate 601, and a mounting seat 603 arranged at the edge of the limit cover plate 60, a cambered surface 604 is arranged on one side surface of the cylinder limiting plate 602 facing the fixed elastic sheet 308, at least one groove 605 is formed on the arc surface 604, the fixing spring plate 308 is clamped on the outer circumferential surface of the cylinder 302 by the deformation of the half ring part 3081, the mounting seat 603 is fixed on a sidewall of the frame 10 so that the cylinder stop plate 602 presses the fixing spring 308 and the cylinder 302 integrally against a sidewall of the frame 10 in a direction approaching the frame 10, the protrusion 3082 is compressively deformably received in the recess 605 to limit deflection of the cylinder 302.

As shown in fig. 3 and 9, the mounting seat 603 includes a plurality of legs 6031, the legs 6031 are provided with through holes 6032, and the frame 10 is provided with threaded holes (not shown) corresponding to the through holes 6032. As shown in fig. 4, the legs 6031 are fixed to the frame 10 by screws 70 passing through the corresponding through holes 6032 and screw holes.

As shown in fig. 1 and fig. 2, one end of the cylinder 302 is formed with a flange 3021, the flange 3021 faces one side of the frame 10 is provided with a limiting block 30211, a side wall of the frame 10 is provided with a limiting groove 101 corresponding to the position of the limiting block 30211, a position where the clutch limiting plate 601 meets the cylinder limiting plate 602 is provided with an avoiding groove 606, the limiting block 30211 is inserted into the limiting groove 101 to realize axial limiting of the cylinder 302, and a part of the flange 3021 departing from the limiting block 30211 is accommodated in the avoiding groove 606. The volume of the cylinder limiting plate 602 can be reduced by the arrangement of the avoiding groove 606, and the installation space of the cylinder limiting plate 602 is reduced.

As shown in fig. 2 and 5, an arc-shaped groove 102 is formed on the frame 10, a portion of the cylinder 302 facing away from the cylinder limit plate 602 is disposed in the arc-shaped groove 102, and the limit groove 101 is located at one end of the arc-shaped groove 102.

As shown in fig. 4 and 5, the half ring portion 3081 includes a plurality of segmental arc plates 30811, the protruding portion 3082 is connected between two adjacent segmental arc plates 30811, and the segmental arc plates 30811 are spaced apart from the arc surface 604.

In an embodiment of the present invention, as shown in fig. 5 to 7, the protruding portion 3082 is provided in plural, the protruding portions 3082 are distributed on the same circumference at equal intervals, the protruding portions 3082 protrude along a radial direction of the circumference where the protruding portions 3082 are located, and a length direction of the groove 605 is consistent with an axial direction of the cylinder 302. Thus, when the protrusion 3082 is compressively and deformably received in the groove 605, the two opposing inner walls of the groove 605 extending in the axial direction of the cylinder 302 can restrict the deflection of the cylinder 302 about its axis.

In an embodiment of the invention, as shown in fig. 5, the half ring portion 3081 further includes a first holding plate 30812 and a second holding plate 30813 formed at two ends of the half ring portion 3081, the first holding plate 30812 and the second holding plate 30813 are plate-shaped, the first holding plate 30812 and the second holding plate 30813 are clamped on the outer circumferential surface of the cylinder 302 in a relatively parallel manner, and a surface of the first holding plate 30812 facing away from the cylinder 302 is in contact with a surface of the cylinder stopper plate 602 facing one side of the fixing spring plate 308. Thus, the first clamping plate 30812 is pressed between the cylinder limiting plate 602 and the cylinder 302, and the mounting position of the fixing elastic piece 308 is stable and difficult to deviate.

In an embodiment of the present invention, as shown in fig. 5 to 7, an arc-shaped mating surface 30821 is formed at the top of the protrusion 3082, two ends of the bottom of the protrusion 3082 are spaced apart from each other to form an extrusion deformation space 30822 inside the protrusion 3082, the groove 605 has an arc-shaped wall surface, and the arc-shaped mating surface 30821 is attached to the arc-shaped wall surface of the groove 605 after the protrusion 3082 is extruded and deformed. The portion of the protruding portion 3082 below the arc-shaped mating surface 30821 is spaced from the arc-shaped surface 604, that is, after the protruding portion 3082 is deformed by pressing, the arc-shaped wall surface of the protruding portion 3082 only contacts the arc-shaped mating surface 30821.

When the fixing structure of the pyrotechnic pretensioning mechanism according to the embodiment of the invention is assembled, firstly, the cylinder 302 is placed on the arc-shaped groove 102 on the frame 10, and the limiting block 30211 of the flange 3021 of the cylinder 302 is inserted in alignment with the limiting groove 101 on the frame 10, so that the mounting and the prepositioning are realized.

Then, as shown in fig. 6, the fixing spring 308 is inserted on the outer circumferential surface of the cylinder 302 along the opening between the first holding plate 30812 and the second holding plate 30813, and in the process, the cylinder 302 presses the fixing spring 308 to slightly deform the half ring portion 3081, so that the fixing spring 308 is clamped on the outer circumferential surface of the cylinder body 302 by the deformation of the half ring portion 3081. The fixed spring piece 308 is deformed from the position of the broken line in fig. 6 to the position of the solid line in fig. 6 by the pressing of the cylinder 302.

Then, as shown in fig. 7, the limiting cover plate 60 is buckled on the fixing elastic sheet 308, the protruding portion 3082 of the fixing elastic sheet 308 is pressed, the fixing elastic sheet 308 is pressed by the cylinder 302 and the limiting cover plate 60 in a two-way manner and is deformed from the dotted line position in fig. 7 to the solid line position in fig. 7, the protruding portion 3082 is pressed by the cylinder 302 and the limiting cover plate 60 in a two-way manner and is deformed from the dotted line position in fig. 8 to the solid line position in fig. 8, the protruding portion 3082 is squashed, the lateral dimension of the pressing deformation space 30822 is enlarged (the interval between the two ends of the bottom of the protruding portion 3082 is enlarged), the arc-shaped matching surface 30821 on the top of the protruding portion 3082 is completely attached to the arc-shaped wall surface of the groove 605 from the dotted line position, the arc-shaped wall surface of the protruding portion 3082 is only in contact with the arc-shaped matching surface 30821, the portion 3082 below the arc-shaped matching surface 30821 is spaced from the arc-shaped surface 604, and the resulting deformation of the protruding portion 3082 is difficult.

Finally, the legs 6031 of the mounting seat 603 of the position limiting cover 60 are fixed to one side wall of the frame 10 by the screws 70, so that the cylinder position limiting plate 602 presses the fixing elastic piece 308 and the cylinder 302 to the one side wall of the frame 10 in a direction approaching the frame 10. Therefore, the fixing elastic sheet 308 connects the cylinder 302, the fixing elastic sheet 308 and the limiting cover plate 60 into a whole under the bidirectional extrusion of the limiting cover plate 60 and the cylinder 302. The protrusion 3082 is compressively and deformably received in the recess 605 to limit deflection of the cylinder 302, ensuring that the cylinder 302 does not experience deflection looseness such as jolting, impacting and vibrating.

In addition, after the assembly, the arc-shaped matching surface 30821 is attached to the arc-shaped wall surface of the groove 605, namely the protruding portion 3082 is in arc surface contact with the cylinder limiting plate 602, and the force transmission and deformation between the protruding portion 3082 and the cylinder limiting plate 602 can be adjusted in a self-adaptive mode to achieve fine adjustment, so that the assembly is facilitated. Moreover, the plurality of convex parts 3082 of the fixed elastic sheet 308 press the cylinder 302 from different angles, so that the situation that the cylinder 302 is inclined and loosened under the conditions of bumping, impact, vibration and the like can be ensured to the maximum extent.

The fixing structure of the pyrotechnic pretensioning mechanism and the safety belt retractor of the embodiment of the invention save fixing parts such as screws (i.e. the fixing elastic sheet 308 does not need additional fixing parts), simplify the processing technology of the independent fixing parts, have the cost advantage, simultaneously have simpler and more convenient assembly and more stable fixing and guiding, and also ensure more stable and reliable function realization of the pyrotechnic pretensioning mechanism.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. A fixed structure of a pyrotechnic pre-tensioning mechanism comprises a frame, a cylinder, a fixed elastic sheet and a limiting cover plate, wherein the cylinder is a circular pipe component, and the fixed elastic sheet comprises a semi-ring part and at least one bulge part formed on the semi-ring part, the limiting cover plate comprises a clutch limiting plate, a cylinder limiting plate connected to one side of the clutch limiting plate and a mounting seat arranged at the edge position of the limiting cover plate, the surface of one side, facing the fixed elastic sheet, of the cylinder limiting plate is provided with a cambered surface, the cambered surface is provided with at least one groove, the fixed elastic sheet is clamped on the outer circumferential surface of the cylinder through the deformation of the semi-ring part, the mounting seat is fixed on one side wall of the frame so that the cylinder limiting plate integrally compresses the fixed elastic sheet and the cylinder on one side wall of the frame towards the direction close to the frame, the projection is compressively deformably received in the groove to restrict deflection of the cylinder.

2. The pyrotechnic pre-tensioning mechanism fixing structure as claimed in claim 1, wherein the semi-ring portion comprises a plurality of segmental arc plates, the protruding portion is connected between two adjacent segmental arc plates, and the segmental arc plates and the arc surfaces are spaced from each other.

3. The pyrotechnic pre-tensioning mechanism fixing structure according to claim 2, wherein the plurality of the protrusions are arranged, the plurality of the protrusions are distributed at equal intervals on the same circumference, the plurality of the protrusions protrude in the radial direction of the circumference where the plurality of the protrusions are located, and the length direction of the groove is consistent with the axial direction of the cylinder.

4. The pyrotechnic pre-tensioning mechanism fixing structure according to claim 1, wherein the semi-ring portion comprises a first clamping plate and a second clamping plate which are formed at two ends of the semi-ring portion, the first clamping plate and the second clamping plate are clamped on the outer circumferential surface of the cylinder in a relatively parallel manner, and the surface of the first clamping plate, which is away from the cylinder, is in contact with one side surface of the cylinder limiting plate, which faces the fixing elastic sheet.

5. The pyrotechnic pre-tensioning mechanism fixing structure as claimed in claim 1, wherein the top of the protrusion forms an arc-shaped fitting surface, both ends of the bottom of the protrusion are spaced apart from each other to form an extrusion deformation space inside the protrusion, and the groove has an arc-shaped wall surface which is fitted to the arc-shaped wall surface of the groove after the protrusion is extruded and deformed.

6. The pyrotechnic pre-tensioning mechanism fixing structure according to claim 5, wherein the portion of the projection below the arc-shaped mating surface is spaced from the arc-shaped surface.

7. The pyrotechnic pre-tensioning mechanism fixing structure according to claim 1, wherein the mounting base comprises a plurality of support legs, through holes are formed in the support legs, threaded holes are formed in the frame at positions corresponding to the through holes, and the support legs are fixed to the frame by screws passing through the corresponding through holes and the threaded holes.

8. The pyrotechnic pre-tensioning mechanism fixing structure as claimed in claim 1, wherein a flange is formed at one end of the cylinder, the flange faces one side of the frame and is provided with a limiting block, a limiting groove is formed in a side wall of the frame corresponding to the limiting block, an avoiding groove is formed in a position where the clutch limiting plate is connected with the cylinder limiting plate, the limiting block is inserted into the limiting groove, and a part of the flange departing from the limiting block is accommodated in the avoiding groove.

9. The pyrotechnic pre-tensioning mechanism fixing structure according to claim 8, wherein an arc-shaped groove is formed in the frame, a part of the cylinder, which is away from the cylinder limiting plate, is arranged in the arc-shaped groove, and the limiting groove is located at one end of the arc-shaped groove.

10. A seat belt retractor comprising the fixed structure of the pyrotechnic pretensioning mechanism of any one of claims 1 to 9.