Piston, safety belt retractor and pre-tightening safety belt

Abstract

The invention relates to a piston for a pre-tightening safety belt, a safety belt retractor and the pre-tightening safety belt. The piston includes: a piston seat including a front surface and a first recess recessed from the front surface; and a piston head which is fitted to the front side of the piston seat and includes an abutting surface abutting the front surface, and the front side of which is provided with a second recess. The piston is provided with a pressure control mechanism, and the pressure control mechanism is configured to stop airflow from flowing forwards when the gas pressure on the rear side of the piston seat is smaller than a preset value; when the gas pressure on the rear side of the piston seat is larger than or equal to a preset value, an airflow channel is formed and is suitable for deflecting airflow and allowing the airflow to flow towards the front of the piston. The piston has a good sealing characteristic, can realize pressure relief under an abnormal working condition, and is simple in structure, convenient to manufacture and lower in cost.

Description

Technical Field

[0001] The present invention generally relates to the field of vehicle passive safety devices, and more specifically, to a piston for a pre-tensioned seat belt. In addition, the present invention also relates to a seat belt retractor including such a piston, and to a pre-tensioned seat belt including such a seat belt retractor. Background Art

[0002] The gap between the webbing and the person is not enough for the retractor of the non-pretensioned seat belt, which is reduced by the retraction force of the coil spring. In addition, the thickness of the person's clothes is also certain. These gaps will also have a huge impact on the safety of the vehicle occupants in an emergency. With the development of science and technology, people's requirements for the protection of vehicle occupants are constantly increasing, and the demand for pretensioned seat belts is increasing.

[0003] For pre-tensioned seat belts, the pre-tensioner can release high energy in the retractor before or after an emergency occurs, instantly tighten the webbing with a greater force that the occupant can withstand, further reduce the gap between the webbing and the occupant's body and restrict the occupant to the designed position, so as to form a coordinated protection with the subsequent activation of the airbag. The basic working principle of the pre-tensioner is that the gas generator is triggered, and the high-pressure airflow generated passes through the piston and the transmission medium to rotate the reel in the seat belt retractor to achieve the effect of instantly tightening the webbing to restrain the occupant on the seat. At the same time, under abnormal working conditions, such as when the gas pressure is too high, in order to protect other components of the pre-tensioner, the piston in the pre-tensioner can release pressure for pressure relief.

[0004] Patent document WO2017 / 021494A1 discloses a seal with internal pressure relief function for a seat belt retractor, wherein a set of metal parts subassembly is embedded in the seal, the bottom is supported by metal parts and preload balls, and the internal pressure relief is achieved by rupturing the center metal cap. However, the assembly has many parts, the assembly process is complicated, and the quality cost is high.

[0005] Patent document EP3059137A1 also discloses a seal with internal pressure relief function for a seat belt retractor, wherein the internal pressure relief is achieved by directly opening a hole in the center of the seal, the seal and the bottom support are separately arranged, and the bottom support is provided with an air relief hole, but this opening method affects the strength of the seal and also affects the preload performance. Summary of the invention

[0006] The object of the present invention is to provide a piston for a pretensioner seat belt to overcome at least one of the above-mentioned defects in the prior art. More specifically, the piston has good sealing performance and can achieve pressure relief under abnormal working conditions, and has a simple structure, is easy to manufacture, and has low cost.

[0007] To this end, the first aspect of the present invention provides a piston for a pretensioner seat belt, comprising: a piston seat, the piston seat comprising a front surface and a first recessed portion recessed from the front surface; and a piston head, the piston head is assembled to the front side of the piston seat and comprises an abutting surface abutting against the front surface, and the front side of the piston head is provided with a second recessed portion suitable for supporting a transmission member. The piston is provided with a pressure control mechanism, the pressure control mechanism is configured to: block the forward flow of airflow when the gas pressure at the rear side of the piston seat is less than a preset value; and form an airflow channel when the gas pressure at the rear side of the piston seat is greater than or equal to the preset value, the airflow channel being suitable for deflecting the airflow and allowing the gas to flow toward the front of the piston.

[0008] According to an optional embodiment of the present invention, the piston seat includes at least one assembly portion protruding from the front surface, and the piston head includes an assembly groove snap-fitted with the at least one assembly portion.

[0009] According to an optional embodiment of the present invention, a third recess is provided on the rear side of the piston seat, and the third recess includes a middle part and an edge part located outside the middle part, the middle part defines an assembly surface suitable for fitting an assembly tool, and the edge part is recessed from the edge of the assembly surface to form an annular edge suitable for radially outward deformation.

[0010] According to an optional implementation of the present invention, the assembly surface is a curved surface.

[0011] According to an optional embodiment of the present invention, the pressure control mechanism is constructed to include: a first channel inlet recessed from the bottom of the middle part; a first channel outlet recessed from the bottom of the first recess; and a barrier portion located between the first channel inlet and the first channel outlet, wherein the barrier portion is configured to rupture to connect the first channel inlet and the first channel outlet when the gas pressure in the third recess is greater than or equal to the preset value.

[0012] According to an optional embodiment of the present invention, the pressure control mechanism is constructed to include: a first channel connecting the middle part and the first recess; and a barrier member arranged in the first channel, wherein the barrier member is configured to close the first channel when the gas pressure in the third recess is less than the preset value, and to rupture to open the first channel when the gas pressure in the third recess is greater than or equal to the preset value.

[0013] According to an optional embodiment of the present invention, the pressure control mechanism further comprises at least one second channel defined by the piston head, and the at least one second channel is configured to guide the airflow in the first recess from the abutment surface to the side wall surface of the piston head.

[0014] According to an optional embodiment of the present invention, the piston head includes a supporting portion protruding from the abutment surface and abutting against the first recess, and the pressure control mechanism also includes at least one second channel defined by the piston head, and the at least one second channel is configured to guide the airflow in the first recess from the supporting portion to the side wall surface of the piston head.

[0015] According to an optional embodiment of the present invention, the first recess connects the front surface and the middle part, and the piston head includes a support portion protruding from the abutment surface and abutting against the inner wall of the first recess, wherein the pressure control mechanism includes: a first channel defined by the support portion, the first channel being configured to be closed when the gas pressure in the third recess is less than the preset value, and to be opened when the gas pressure in the third recess is greater than or equal to the preset value to guide the airflow from the third recess to the position of the abutment surface; and at least one second channel, the at least one second channel being configured to be connected to the first channel and guide the airflow from the position of the abutment surface to the side wall surface of the piston head.

[0016] According to an optional embodiment of the present invention, the pressure control mechanism is configured such that an angle between a direction of the airflow output from the airflow channel and an axial direction of the piston is between 20° and 90°.

[0017] According to an optional embodiment of the present invention, the piston seat is made of a first plastic material, and the piston head is made of a second plastic material having a harderness than that of the first plastic material.

[0018] The second aspect of the present invention provides a seat belt retractor, comprising: a bracket; a reel assembly rotatably mounted to the bracket, the reel assembly comprising a reel suitable for winding a webbing and a gear fixedly connected to the reel; a pretensioning pipe mounted to the bracket; a gas generator mounted in the pretensioning pipe; and at least one piston according to the first aspect of the present invention and at least one transmission member arranged in the pretensioning pipe, the piston being arranged between the gas generator and the transmission member, and the piston seat having an interference fit with the inner wall of the pretensioning pipe, the seat belt retractor being configured to generate an airflow when the gas generator is ignited to push the piston and the transmission member to move in the pretensioning pipe, so that the transmission member interacts with the gear and drives the reel to rotate.

[0019] A third aspect of the present invention provides a pretensioned seat belt, comprising the seat belt retractor according to the second aspect of the present invention.

[0020] Compared with the prior art, the piston for pretensioning seat belts according to the present invention has several advantages, in particular: through a seat belt retractor with such a piston, the gap between the webbing and the occupant can be quickly tightened to restrain the occupant in the event of a vehicle collision, wherein the energy is fully utilized through the good sealing characteristics of the piston, the amount of gunpowder used is reduced, and the efficiency of the pretensioning function is improved, and at the same time, a pressure control mechanism is provided in the piston in a simple and low-cost manner, so that abnormal pressure can be released through the control structure to protect other components of the seat belt, and the flame can also be suppressed and the gas injection energy can be reduced during the release; in addition, the piston has a simple structure, is easy to assemble, and has a low cost, and can be widely used in various types of seat belt retractors. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other features and advantages of the present invention will be better understood through the following preferred embodiments described in detail in conjunction with the accompanying drawings. In the accompanying drawings, the same reference numerals represent the same or similar components.

[0022] Figure 1 is a perspective view of a seat belt retractor according to an embodiment of the present invention;

[0023] Figure 2 yes Figure 1 A cross-sectional view of the seat belt retractor at the gear position of the pretensioner;

[0024] Figure 3 yes Figure 1 A cross-sectional view of a pretensioning pipe of a pretensioning device of a seat belt retractor;

[0025] FIG. 4A to FIG. 4D A perspective view, an exploded view, a side view and a cross-sectional view of a piston according to a first embodiment of the present invention, respectively;

[0026] FIG. 5A to FIG. 5D A perspective view, an exploded view, a side view and a cross-sectional view of a piston according to a second embodiment of the present invention, respectively;

[0027] FIG. 6A to FIG. 6D A perspective view, an exploded view, a side view and a cross-sectional view of a piston according to a third embodiment of the present invention, respectively;

[0028] FIG. 7A to FIG. 7D A perspective view, an exploded view, a side view and a cross-sectional view of a piston according to a fourth embodiment of the present invention, respectively;

[0029] FIG. 8A to FIG. 8D 3D 3D are a perspective view, an exploded view, a side view and a cross-sectional view of a piston according to a fifth embodiment of the present invention, respectively.

[0030] The elements in the drawings are shown for simplicity and clarity and are not necessarily drawn to exact scale. It should be understood that the drawings are not only used to explain and illustrate the present invention, but also to help define the present invention when necessary. DETAILED DESCRIPTION

[0031] The implementation and use of specific embodiments are discussed in detail below. However, it should be understood that the specific embodiments discussed are merely illustrative of specific ways to implement and use the invention, and are not intended to limit the scope of the invention.

[0032] like Figures 1 to 3 As shown, the present invention relates to a seat belt retractor for a pretensioned seat belt, which mainly includes a bracket 10, a reel assembly 20, a pretensioning pipe 30, an outer cover 40, a gas generator 50, at least one piston 60 and at least one transmission member, such as the pretensioning ball 70 shown.

[0033] The bracket 10 is configured as a U-shaped bracket and fixed to a seat of a vehicle. The reel assembly 20 is rotatably mounted on the bracket 10 and includes a reel 21 for winding a webbing and a gear 22 fixedly connected to the reel 21. For example, a spline shaft is provided at one axial end of the reel 21, and the gear 22 is sleeved on the spline shaft without relative rotation so that it can rotate with the reel 21, and the tooth portion of the gear 22 has a special-shaped meshing portion adapted to the transmission member. The outer cover 40 is mounted on the bracket 10 to cover the axial end of the reel 21.

[0034] The pre-tensioning pipe 30 is mounted on the bracket 10 and is configured as a serpentine bend, for example. The gas generator 50 is assembled into the pre-tensioning pipe 30 at one end of the pre-tensioning pipe 30, for example, by riveting. The piston 60 and a plurality of pre-tensioning balls 70 as transmission parts are accommodated and retained in the pre-tensioning pipe 30, and the piston 60 is arranged between the gas generator 50 and the pre-tensioning balls 70 and is interference-fitted with the inner wall 31 of the pre-tensioning pipe 30. Thus, the pre-tensioning pipe 30, the gas generator 50, the piston 60, the pre-tensioning balls 70 and the gear 22 constitute the pre-tensioning device of the seat belt retractor.

[0035] When an emergency occurs, the gas generator 50 is ignited to generate a high-temperature and high-pressure airflow, which in turn pushes the piston 60 and the pre-tightening ball 70 to move in the pre-tightening pipe 30. The outlet of the end of the pre-tightening pipe 30 opposite to the gas generator 50 is aligned with the tooth portion of the gear 22, so that the pre-tightening ball 70 meshes with the special-shaped meshing portion of the tooth portion of the gear 22 when ejected from the outlet of the pre-tightening pipe 30, thereby driving the gear 22 to rotate and driving the reel 21 to rotate to instantly tighten the webbing. The special-shaped meshing portion of the tooth portion of the gear 22 can be configured as a ball socket, for example, so as to achieve good meshing of the pre-tightening ball 70 and the gear 22.

[0036] The following uses FIG. 4A to FIG. 8D Specific embodiments of the piston 60 are described below. In the present specification, the front side of the piston 60 is the side facing the preload ball 70, and the rear side of the piston 60 is the side facing the gas generator 50. In addition, in the present specification, unless otherwise clearly defined, "axial" and "radial" both refer to the axial direction and radial direction of the piston 60.

[0037] First embodiment

[0038] like FIG. 4A to FIG. 4D As shown, the piston 60 includes a piston seat 61 and a piston head 62 assembled to the front side of the piston seat 61. The piston seat 61 can play a sealing role. More specifically, when the gas generator 50 is ignited, the gas pressure on the rear side of the piston seat 61 can cause the piston seat 61 to deform under force to tighten the gap between the piston seat 61 and the inner wall 31 of the preload pipe 30, thereby achieving a sealing effect.

[0039] The front side of the piston seat 61 includes a front surface 611, a first recessed portion 613 recessed backward from the front surface 611, and at least one assembly portion 612 protruding from the front surface 611, such as three assembly portions 612 uniformly distributed circumferentially on the front surface 611 as shown. Correspondingly, the piston head 62 includes an annular assembly groove 624 recessed radially inward from its side wall surface 623 (i.e., the surface facing the inner wall 31 of the preloaded pipe 30) to engage with the protrusion on each assembly portion 612, so that the piston head 62 is fixedly assembled to the front side of the piston seat 61, and the abutting surface 622 of the piston head 62 (i.e., the rear surface of the piston head 62) is tightly abutted against the front surface 611 of the piston seat 61. It can be understood that the above-mentioned assembly method of the piston seat 61 and the piston head 62 is not restrictive, and the shape, position, assembly method, etc. of the assembly portions of the two can be changed according to actual needs.

[0040] The front side of the piston head 62 is provided with a second recess 621 for supporting the transmission member, and the second recess 621, for example, defines an arc surface for supporting and pushing the preload ball 70, especially a spherical surface with a spherical surface feature of 10%-45%, so that the second recess 621 forms a surface contact with the preload ball 70. In addition, the arc surface can also be provided with multiple protrusions, so that the second recess 621 forms a multi-point center-symmetrical contact with the preload ball 70. The overall radial size of the piston head 62 should account for 20%-100% of the cross-sectional area of ​​the preload pipe 30.

[0041] The rear side of the piston seat 61 is provided with a third recessed portion facing the gas generator 50, and the third recessed portion includes a middle portion 615 and an edge portion 614 located outside the middle portion 615. The middle portion 615 defines an assembly surface 6151, and the assembly surface 6151 is, for example, configured as an arcuate surface (such as a spherical surface or other curved surface) for fitting the outer contour of the assembly tool. Thus, it is convenient for the assembly tool to hold the piston 60 through the assembly surface 6151 and install it into the preloaded pipe 30. The edge portion 614 is recessed outward from the edge of the assembly surface 6151 to form a tail ring edge 6141 of the piston 60. Thus, when assembling the piston 60, due to the uneven transition between the inner wall surface 6142 of the ring edge 6141 and the assembly surface 6151, the assembly tool will not contact the ring edge 6141 and cause wear thereof. In addition, due to the small thickness of the ring edge 6141, when the gas generator 50 is ignited, the airflow in the third recess of the piston seat 61 can push the ring edge 6141 to expand and deform radially outward, so that the outer wall surface of the ring edge 6141 can fit the inner wall 31 of the preloaded pipe 30 more closely than other outer wall portions of the piston seat 61, thereby further improving the sealing performance. It can be understood that the inner wall surface 6142 of the ring edge 6141 can be a flat surface or a curved surface, and the present invention is not limited to this.

[0042] According to the first embodiment, the pressure control mechanism of the piston 60 includes a first channel inlet 616 recessed forward from the bottom of the middle portion 615 of the third recess of the piston seat 61, a first channel outlet 617 recessed backward from the bottom of the first recess 613 of the piston seat 61, and a baffle 618 located between the first channel inlet 616 and the first channel outlet 617. More specifically, the first channel inlet 616 and the first channel outlet 617 have radial dimensions reduced compared to the middle portion 615 and the first recess 613 and are separated by the baffle 618; the baffle 618 itself, as a part of the integrated piston seat 61, constitutes a diaphragm-like structure in the piston seat 61 that can be broken at a preset pressure and temperature. Therefore, when the gas pressure on the rear side of the piston seat 61 (i.e., the gas pressure in the third recess) is less than a preset value, the barrier portion 618 can block the airflow from flowing forward; and when the gas pressure on the rear side of the piston seat 61 is greater than or equal to the preset value, due to the setting of the first recess 613, the rear part of the piston seat 61 is more likely to shrink and deform radially inward, and the barrier portion 618 can thus be easily broken to connect the first channel inlet 616 with the first channel outlet 617, thereby forming a first channel, so that the airflow on the rear side of the piston seat 61 can reach the first recess 613 via the first channel.

[0043] The pressure control mechanism of the piston 60 further includes at least one second channel 625 defined by the piston head 62, for example, one to eight second channels 625, which are grooves opened along the edge of the piston head 62, and the grooves extend from the abutment surface 622 of the piston head 62 to the side wall surface 623, so as to guide the airflow reaching the first recess 613 from the abutment surface 622 to the side wall surface 623 and spray toward the inner wall 31 of the preload pipe 30, and then flow toward the front of the piston 60. In fact, the second channel 625 constitutes an energy dissipation structure of the pressure control mechanism, which deflects the airflow output from the first channel to reduce the energy of the airflow spray and suppresses the generation of flames. Preferably, the angle between the direction of the airflow output from the second channel 625 and impacting the inner wall 31 of the preload pipe 30 and the axial direction of the piston 60 (i.e., the direction of the airflow flowing through the first channel) is between 20° and 90°. For example, the second channel 625 may be configured to extend radially from the center of the abutting surface 622 of the piston head 62 to the outer wall surface 623 thereof along the abutting surface 622 , so that the airflow may vertically impact the inner wall 31 of the preload pipe 30 .

[0044] Preferably, the piston seat 61 is made of a first plastic material, such as POM (polyoxymethylene resin), which can not only ensure an interference fit with the preload pipe 30 to obtain a better seal, but also make the baffle 618 of the pressure control mechanism rupture when the air pressure is too high, thereby ensuring safety; the piston head 62 is made of a second plastic material with a hardness greater than that of the first plastic material, such as nylon with glass fiber, to ensure support for the preload ball 70 and transfer energy. Of course, the piston seat 61 and the piston head 62 can also be made of the same material that meets the performance requirements, and the present invention does not limit this. In addition, in order to further suppress the generation of flames, the material of the piston seat 61 and / or the piston head 62 can be selected as a flame retardant material, or can contain a flame retardant additive component.

[0045] It can be understood that the specific materials listed above are only illustrative and not restrictive. In fact, any suitable materials can be selected for the piston seat 61 and the piston head 62 so that the piston 60 has sufficient heat resistance and ablation resistance and a high melting point. In other words, the selected material enables the piston 60 to withstand the friction heat between the piston 60 and the pre-tightening pipe 30 and the high temperature of the gunpowder during the working process, so that the contact surface between the piston 60 and the pre-tightening pipe 30 will not form leakage caused by heat or ablation.

[0046] It is also preferred that the size of the piston seat 61 is set so that the piston seat 61 has a basically cylindrical shape, the diameter of the piston seat 61 is larger than the diameter of the inner wall 31 of the preload pipe 30 so that the piston seat 61 forms an interference fit with the preload pipe 30, and the ratio of the length and diameter of the piston seat 61 is greater than or equal to 0.8, and more preferably greater than or equal to 1, so that when the piston 60 is forced to move in the opposite direction of the preload, there is sufficient contact area with the inner wall 31 of the preload pipe 30 to provide resistance through friction so that the piston 60 hardly retreats.

[0047] Second embodiment

[0048] It should be understood that different embodiments of the piston 60 according to the present invention have similar overall structures. Therefore, in the description of other embodiments, the same points as those of the embodiments already described will not be repeated.

[0049] like FIG. 5A to FIG. 5D As shown, in the second embodiment, the difference from the first embodiment is that the piston head 62 includes a support portion 626 that protrudes backward from the abutting surface 622 and abuts against the first recess 613 of the piston seat 61. More specifically, the support portion 626 completely extends into the first recess 613 to closely abut and support the inner wall of the first recess 613. Due to the provision of the support portion 626, a more stable assembly between the piston head 62 and the piston seat 61 is ensured, thereby ensuring the stable movement of the piston 60 in the preload pipe 30 and preventing the piston 60 from turning over and jumping during the movement.

[0050] In this construction, at least one second channel 625 defined by the piston head 62 is, for example, a groove opened along the edge of the piston head 62, which extends from the end face 627 of the support portion 626 facing the first channel outlet 617 to the side wall surface 623, so as to guide the airflow reaching the first recess 613 from the support portion 626 to the side wall surface 623 of the piston head 62 and spray it toward the inner wall 31 of the preload pipe 30, and then flow toward the front of the piston 60.

[0051] Third embodiment

[0052] like FIG. 6A to FIG. 6D As shown, in the third embodiment, the difference from the first embodiment is that the first channel of the pressure control mechanism of the piston 60 includes a first channel inlet 616 recessed forward from the bottom of the middle portion 615 of the third recess of the piston seat 61, a first channel outlet 617 recessed backward from the bottom of the first recess 613 of the piston seat 61, and a connecting channel 619 connecting the first channel inlet 616 and the first channel outlet 617. Therefore, the middle portion 615 of the third recess is connected to the first recess 613 through the first channel.

[0053] In addition, the pressure control mechanism further includes a barrier 63 arranged in the first channel, and the barrier 63 can be arranged in the first channel inlet 616 as shown in the figure, or in the first channel outlet 617 or in the connecting channel 619. The barrier 63 is a plastic part or a metal part, and its function is similar to the barrier part 618 in the first embodiment, that is, it constitutes a diaphragm-like structure in the piston seat 61 that can be broken at a preset pressure and temperature. More specifically, when the gas pressure on the rear side of the piston seat 61 (i.e., the gas pressure in the third recess) is less than a preset value, the barrier 63 can close the first channel to block the forward flow of the airflow; when the gas pressure on the rear side of the piston seat 61 is greater than or equal to the preset value, the barrier 63 can be broken through the fragile areas such as the weakened part and the tear line arranged thereon to open the first channel, so that the airflow on the rear side of the piston seat 61 reaches the first recess 613 via the first channel. The present invention does not limit the shape, material, and breaking mode of the barrier 63.

[0054] Fourth embodiment

[0055] like FIG. 7A to FIG. 7D As shown, in the fourth embodiment, the difference from the third embodiment is that the structure of the piston head 62 is similar to that of the second embodiment, that is, the piston head 62 includes a support portion 626 that protrudes backward from the abutting surface 622 and abuts against the first recess 613 of the piston seat 61, and the groove forming the second channel 625 guides the airflow reaching the first recess 613 from the support portion 626 to the side wall surface 623 of the piston head 62. For details, please refer to the second embodiment, and the description will not be repeated here.

[0056] Fifth embodiment

[0057] like FIG. 8A to FIG. 8D As shown, in the fifth embodiment, the difference from the fourth embodiment lies in the arrangement of the first channel, that is, the first channel and the second channel 625 are both arranged in the piston head 62.

[0058] More specifically, in the piston seat 61, the first recess 613 connects the front surface 611 and the middle portion 615 of the third recess, and the support portion 626 of the piston head 62 completely extends into the first recess 613 toward the middle portion 615 to closely abut and support the inner wall of the first recess 613. In the fifth embodiment, the first channel of the pressure control mechanism of the piston 60 is arranged in the support portion 626 of the piston head 62. More specifically, the support portion 626 defines a first channel connecting the third recess of the piston seat 61 and the substantially central position of the abutting surface 622 of the piston head 62, and the first channel includes an inlet section 628 and a connecting section 629 connecting the inlet section 628 and the substantially central position of the abutting surface 622. The barrier 63 can be arranged in the inlet section 628 as shown in the figure, or in the connecting section 629.

[0059] When the gas pressure at the rear side of the piston seat 61 (i.e., the gas pressure in the third recess) is less than a preset value, the barrier 63 can close the first channel to block the forward flow of the gas flow; when the gas pressure at the rear side of the piston seat 61 is greater than or equal to the preset value, the barrier 63 can rupture through fragile areas such as weakened portions and tear lines provided thereon to open the first channel, so as to guide the gas flow at the rear side of the piston seat 61 through the first channel to the approximate center position of the abutment surface 622. It can be understood that the first channel can also be constructed in a form similar to the first embodiment, that is, the barrier 63 can be replaced by a barrier portion integrally formed in the piston head 62 to reduce the number of parts.

[0060] In addition, at least one second channel 625 defined by the piston head 62 is connected to the first channel at the end of the connecting section 629, and guides the airflow reaching the abutment surface 622 from the approximate center position of the abutment surface 622 to the side wall surface 623 of the piston head 62 and sprays toward the inner wall 31 of the preload pipe 30, and then flows toward the front of the piston 60.

[0061] Based on the above detailed description of multiple non-exhaustive embodiments, it can be known that the piston 60 according to the present invention has a simple overall structure, a small number of parts, and a simple and reliable assembly process, so the production, process, and quality costs are low. When the pre-tightening takes effect, the piston 60 has a good sealing performance to ensure gas sealing and energy transfer, while taking into account the response rate of power transmission and reducing hysteresis. When the pre-tightening device reaches the limit working condition, in order to ensure the safety of the pre-tightening device and avoid the bursting of the pre-tightening pipe 30, the piston can release the high-temperature and high-pressure airflow in the pre-tightening pipe 30, and can also effectively avoid the damage to the vehicle interior and the injury to the occupants caused by open flames, high-energy particles, etc.

[0062] It should be noted that the present invention (e.g., the inventive concept, etc.) has been described in the specification of this patent document and / or illustrated in the drawings according to exemplary embodiments; the embodiments of the present invention are presented only by way of example and are not intended to limit the scope of the present invention. The structure and / or arrangement of the elements of the inventive concept embodied in the present invention as described in the specification and / or illustrated in the drawings is merely illustrative. Although exemplary embodiments of the present invention have been described in detail in this patent document, it is readily understood by those of ordinary skill in the art that equivalents, modifications, variations, etc. of the subject matter of the exemplary embodiments and alternative embodiments are possible and are considered to be within the scope of the present invention; all of these subject matters (e.g., modifications, variations, embodiments, combinations, equivalents, etc.) are intended to be included within the scope of the present invention. It should also be noted that various other modifications, changes, substitutions, equivalents, alterations, omissions, etc. may be made in the configuration and / or arrangement of the exemplary embodiments (e.g., in terms of concepts, designs, structures, devices, forms, assemblies, constructions, means, functions, systems, processes / methods, steps, the order of process / method steps, operations, operating conditions, performances, materials, compositions, combinations, etc.) without departing from the scope of the present invention; all of these subjects (e.g., modifications, changes, embodiments, combinations, equivalents, etc.) are intended to be included within the scope of the present invention. The scope of the present invention is not intended to be limited to the subject matter (e.g., details, structures, functions, materials, behaviors, steps, sequences, systems, results, etc.) described in the specification and / or drawings of this patent document. Considering that the claims of this patent document will be appropriately interpreted as covering the full scope of the subject matter of the present invention (e.g., including any and all such modifications, changes, embodiments, combinations, equivalents, etc.); it should be understood that the terms used in this patent document are intended to provide a description of the subject matter of the exemplary embodiments, rather than as a limitation on the scope of the present invention.

[0063] It should also be noted that, depending on the exemplary embodiments, the present invention may include conventional technologies (such as technologies implemented and / or integrated in exemplary embodiments, modifications, variations, combinations, equivalents), or may include any other applicable technologies (present and / or future) with the ability to perform the functions and processes / operations described in the specification and / or illustrated in the figures. All of these technologies (such as technologies implemented in embodiments, modifications, variations, combinations, equivalents, etc.) are considered to be within the scope of the present invention of this patent document.

Claims

1. A piston (60) for a pre-tensioning seat belt, characterized in that: include: A piston seat (61), the piston seat (61) comprising a front surface (611) and a first recessed portion (613) recessed from the front surface (611); and A piston head (62), the piston head (62) being assembled to the front side of the piston seat (61) and comprising an abutting surface (622) abutting against the front surface (611), and the front side of the piston head (62) being provided with a second recess (621) suitable for supporting a transmission member; The piston (60) is provided with a pressure control mechanism, and the pressure control mechanism is configured to: block the airflow from flowing forward when the gas pressure on the rear side of the piston seat (61) is less than a preset value; and form an airflow channel when the gas pressure on the rear side of the piston seat (61) is greater than or equal to the preset value, and the airflow channel is suitable for deflecting the airflow and allowing the airflow to flow toward the front of the piston (60).

2. The piston (60) according to claim 1, characterized in that The piston seat (61) comprises at least one assembly portion (612) protruding from the front surface (611), and the piston head (62) comprises an assembly groove (624) that is snap-fitted with the at least one assembly portion (612).

3. The piston (60) according to claim 1, characterized in that A third recess is provided on the rear side of the piston seat (61), and the third recess includes a middle portion (615) and an edge portion (614) located outside the middle portion (615), wherein the middle portion (615) defines an assembly surface (6151) suitable for fitting an assembly tool, and the edge portion (614) is recessed from the edge of the assembly surface (6151) to form an annular edge (6141) suitable for radially outward deformation.

4. The piston (60) according to claim 3, characterized in that The assembly surface (6151) is an arc-shaped surface.

5. The piston (60) according to claim 3, characterized in that The pressure control mechanism comprises: a first channel inlet (616) recessed from the bottom of the middle portion (615); A first channel outlet (617) recessed from the bottom of the first recess (613); and A barrier portion (618) is located between the first channel inlet (616) and the first channel outlet (617), wherein the barrier portion (618) is configured to rupture when the gas pressure in the third recess is greater than or equal to the preset value to connect the first channel inlet (616) and the first channel outlet (617).

6. The piston (60) according to claim 3, characterized in that The pressure control mechanism comprises: a first passage connecting the middle portion (615) and the first recess (613); and A barrier (63) is arranged in the first channel, wherein the barrier (63) is configured to close the first channel when the gas pressure in the third recess is less than the preset value, and to rupture to open the first channel when the gas pressure in the third recess is greater than or equal to the preset value.

7. The piston (60) according to claim 5 or 6, characterized in that The pressure control mechanism also includes at least one second channel (625) defined by the piston head (62), and the at least one second channel (625) is configured to guide the air flow in the first recess (613) from the abutment surface (622) to the side wall surface (623) of the piston head (62).

8. The piston (60) according to claim 5 or 6, characterized in that The piston head (62) includes a support portion (626) protruding from the abutment surface (622) and abutting against the first recess (613), and the pressure control mechanism also includes at least one second channel (625) defined by the piston head (62), and the at least one second channel (625) is configured to guide the air flow in the first recess (613) from the support portion (626) to the side wall surface (623) of the piston head (62).

9. The piston (60) according to claim 3, characterized in that The first recess (613) communicates the front surface (611) with the middle portion (615), and the piston head (62) includes a support portion (626) protruding from the abutment surface (622) and abutting against the inner wall of the first recess (613), wherein the pressure control mechanism includes: a first channel defined by the support portion (626), the first channel being configured to be closed when the gas pressure in the third recess is less than the preset value, and to be opened when the gas pressure in the third recess is greater than or equal to the preset value to guide the gas flow from the third recess to the position of the abutment surface (622); and At least one second channel (625) is configured to communicate with the first channel and guide the air flow from the position of the abutment surface (622) to the side wall surface (623) of the piston head (62).

10. The piston (60) according to claim 1, characterized in that The pressure control mechanism is configured so that the angle between the direction of the air flow output from the air flow channel and the axial direction of the piston (60) is between 20° and 90°.

11. The piston (60) according to claim 1, characterized in that The piston seat (61) is made of a first plastic material, and the piston head (62) is made of a second plastic material having a harderness than the first plastic material.

12. A seat belt retractor, characterized in that: include: Bracket (10); a reel assembly (20) rotatably mounted to the bracket (10), the reel assembly (20) comprising a reel (21) suitable for winding a webbing and a gear (22) fixedly connected to the reel (21); a pre-tightening pipe (30) assembled to the bracket (10); a gas generator (50) assembled into the preload pipe (30); and At least one piston (60) according to any one of claims 1 to 11 and at least one transmission member are arranged in the preload pipe (30), the piston (60) is arranged between the gas generator (50) and the transmission member, and the piston seat (61) is interference-fitted with the inner wall (31) of the preload pipe (30), The seat belt retractor is configured to generate an airflow when the gas generator (50) is ignited to push the piston (60) and the transmission member to move in the preload pipe (30), so that the transmission member interacts with the gear (22) and drives the reel (21) to rotate.

13. A pre-tensioned safety belt, characterized in that: Comprising a seat belt retractor according to claim 12.

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