A nosepiece pre-tensioner

Abstract

The application discloses an end piece pre-tightener, which comprises a cable, a guide plate, a rubber sealing assembly, a mounting plate, a gas generator, a piston and a cylinder working pipe. The mounting plate is internally provided with a sub-chamber and a main chamber which are in communication with each other, and the gas generator is fixed in the sub-chamber; the guide plate is detachably fixed at the end of the mounting plate and closes the main chamber. The guide plate extends into the main chamber and is provided with a wire protection tube which is arranged on a gas injection path and used for physically isolating and protecting the cable from high-temperature ablation; the wire protection tube is internally embedded with the rubber sealing assembly which is radially contracted to tightly hold the cable under the extrusion of high-pressure gas in the main chamber, so that dynamic self-locking sealing is realized. The mounting plate is externally provided with a cable guide pipe which is used for unloading the cable to release the shearing stress when the cable is bent. The application effectively prevents the cable from being ablated and the risk of edge wire breakage, guarantees absolute air tightness during actuation, and enables the guide plate module to be replaced in situ without cutting off the cable after mis-explosion, so that the after-sales maintenance cost is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of automotive equipment technology, and more specifically to an end piece pretensioner. Background Technology

[0002] As a crucial restraint device in passive safety systems, car seat belts securely fasten occupants to their seats during a collision, effectively mitigating or preventing fatal injuries. A complete seat belt system typically includes components such as a retractor, webbing, buckle, and end tab holders. To further enhance protection, modern cars are generally equipped with pretensioning systems. The main function of the pretensioner is to rapidly pull back the webbing, buckle, or end tabs in the very initial moment of a collision to eliminate any gaps in the seat belt, ensuring the webbing is tightly fitted to the occupant's body. Among these, the end tab pretensioner, with its advantage of directly pulling the cable to tighten the seat belt end downwards, holds an irreplaceable position in the vehicle restraint system.

[0003] Chinese invention patent CN116923311A discloses a "pretensioner" whose working logic is as follows: When a vehicle experiences a severe collision, the vehicle's ECU sends an ignition signal to detonate a gas generator. After the gas generator explodes, a large amount of high-temperature, high-pressure gas is instantly generated in the chamber of the pretensioner. This high-pressure gas flow pushes a piston arranged in the pretension tube (cylinder power tube) to move at high speed. The piston then pulls the cable connected to it, and the cable ultimately pulls the end plate downwards, thus achieving the pretensioning function to eliminate slack.

[0004] However, although the aforementioned existing technologies can achieve basic pre-tightening, they still reveal many structural defects in actual engineering applications and after-sales scenarios. First, existing pre-tightening mounting plates mostly adopt a one-piece cast structure, and the internal air chamber design often directly exposes the cable to the flow channel opening. The high-temperature jet of hundreds of degrees Celsius generated by the gas generator directly impacts the cable surface, easily leading to safety hazards such as annealing, ablation, or even partial wire breakage. Second, existing structures typically use only ordinary static sealing rings. When faced with the extreme high-pressure impact at the moment of detonation and the high-speed pulling of the cable, the seals are prone to deformation or detachment, causing high-pressure gas leakage and resulting in a significant decrease in pre-tightening force. Third, limited by the confined installation space inside the vehicle, the cable usually needs to be bent at a large angle after passing through the mounting plate. When subjected to a pre-tightening force of several thousand Newtons, the cable is prone to severe shearing and frictional wear against the rigid orifice edge of the mounting plate. Finally, in the case of a traditional pre-tightening device made of one-piece casting, the internal parts cannot be disassembled individually after operation or accidental explosion on the production line. The entire set of core components, such as the piston, cylinder power tube, and cable, must be cut off and scrapped, resulting in extremely high after-sales and maintenance costs.

[0005] Therefore, how to avoid the risk of cable ablation by high-temperature gas, improve the dynamic sealing reliability under high pressure, improve the stress state of the cable outlet, and significantly reduce the maintenance cost after the pretensioner explodes are technical problems that urgently need to be solved by those skilled in the art. Summary of the Invention

[0006] To address the risks in existing technologies, such as the susceptibility of cables to high-temperature gas ablation, the vulnerability of high-pressure seals to impact failure, the tendency for edge shearing wear at cable bends, and the high maintenance costs associated with the complete shearing and scrapping of the pretensioner after accidental detonation, this invention provides an end-plate pretensioner. By innovatively splitting the pretensioner end into a mounting plate and a detachable guide plate, and adding a cable protection tube and dynamic sealing assembly within the guide plate, along with a cable guide tube outside the mounting plate, the pretensioner is protected from high-temperature ablation during operation and detonation, achieving a high-pressure dynamic self-locking seal. Under external tension, the cable runs smoothly without shearing. Furthermore, modular in-situ replacement is possible after accidental detonation, improving the overall safety and reliability of the pretensioner, significantly reducing after-sales maintenance costs, and enhancing occupant protection.

[0007] To achieve the objective of this invention, an end-piece pretensioner is provided, comprising a cable, screws, a guide plate, a rubber sealing assembly, a mounting plate, stepped bolts, a gas generator, a piston sealing ring, a piston, a locking ball, a cable tail tube, and a cylinder working tube. The mounting plate has a main chamber and a secondary chamber, which are interconnected. The gas generator is riveted and fixed within the secondary chamber. The guide plate is fixed to one end face of the mounting plate by screws, sealing the port of the main chamber. The cylinder working tube is connected and fixed to the other end of the mounting plate, and its interior is connected to the main chamber. The piston is slidably arranged within the cylinder working tube, and the piston sealing ring is fitted onto the... The locking ball is located in the middle of the piston within the groove on its outer periphery; the cable tail tube is located at the end of the cable and is riveted to the cable; the cable passes sequentially through the guide plate, the rubber sealing assembly, and the main chamber of the mounting plate before extending into the cylinder working tube, passing through the piston within the cylinder working tube, and is riveted to the cable tail tube at the end of the piston; the cable tail tube is connected to the piston via a conical surface fit to transmit the tension between the piston and the cable; the rubber sealing assembly is embedded in the guide plate, and the piston sealing ring and the rubber sealing assembly together ensure the airtightness of the main chamber of the mounting plate during an explosion; the stepped bolt passes through the holes on the mounting plate to connect and fix the mounting plate to the vehicle frame.

[0008] Preferably, the guide plate includes a sleeve and a protective tube that mate with the mounting plate. The sleeve that mates with the mounting plate is inserted into the main cavity of the mounting plate for positioning. The protective tube extends from the sleeve that mates with the mounting plate into the main cavity of the mounting plate. The rubber sealing assembly is embedded inside the protective tube.

[0009] Preferably, when the high-pressure gas generated by the gas generator is injected from the secondary chamber of the mounting plate into the main chamber of the mounting plate, the outer wall of the protective tube is arranged in the gas injection path. The protective tube is used to block the high-pressure gas and physically isolate the high-temperature and high-pressure gas from the cable passing through the inside of the protective tube to prevent the cable from being ablated by high temperature.

[0010] Preferably, the inner wall of the end of the cable sheath away from the sleeve that mates with the mounting plate contracts inward to form an anti-disengagement buckle flange. One end of the rubber sealing assembly is confined to the inside of the anti-disengagement buckle flange to prevent the rubber sealing assembly from coming out of the cable sheath under the impact of high-pressure gas and the pulling of the cable. When high-pressure gas enters the main chamber of the mounting plate, the rubber sealing assembly undergoes radial contraction deformation under the action of gas pressure, tightly gripping the surface of the cable to form a dynamic seal.

[0011] Preferably, the mounting plate has an integrally formed cable guide tube on its exterior. The cable passing through the guide plate is bent and leads outward through the cable guide tube. During pre-tightening and when the cable is under tension, the inner wall of the cable guide tube provides lateral support for the cable, unloading the shear stress on the cable at the center outlet of the guide plate.

[0012] Preferably, the central channel of the guide plate is not only used to accommodate the rubber sealing assembly, but its inner wall also provides radial guidance for the cable. The guide plate constrains the radial runout of the cable to ensure the coaxiality of the cable and the piston when they slide in the cylinder power tube after the cable enters the main cavity of the mounting plate.

[0013] Preferably, the guide plate and the mounting plate cooperate to form a partially replaceable structure to prevent accidental explosion. When the end plate pretensioner is activated or an accidental explosion occurs, the guide plate, together with the embedded failed rubber sealing component, can be slid outward along the cable and replaced as an independent module without cutting the cable by removing the screws.

[0014] Compared with existing technologies, the present invention has the following advantages: This invention solves the problems of direct ablation of cables by high-pressure propellant gas and easy leakage failure of static seals in the prior art by adding a protective tube extending into the air chamber on the guide plate and a rubber sealing component that deforms under pressure. During the collision, the pressurized gas in the main chamber of the pretensioner will preferentially impact the outer wall of the protective tube, and the gas pressure will force the internal rubber sealing component to radially contract and tightly hold the cable, thus achieving a dynamic high-pressure seal with no ablation and zero leakage, improving the air pressure utilization rate, and better securing people to the seat.

[0015] This invention solves the risk of edge shear wear caused by bending and pulling cables in confined spaces in the prior art by adding an integrally formed cable guide tube to the outside of the mounting plate. This allows the lateral force on the cable to be smoothly unloaded by the guide tube when the end plate pretensioner is subjected to thousands of Newtons of force during the pulling stage, preventing stress abrupt changes at the outlet, reducing the probability of cable breakage or damage, and improving the transmission safety of the pretensioner.

[0016] The separate structure of the mounting plate and guide plate of this invention solves the high cost problem of having to cut the cable and discard the entire assembly once the pretensioner is activated or accidentally detonates in the prior art. This allows the guide plate and sealing materials to be replaced separately by simply unscrewing the screws during later maintenance or repair of accidental detonation, reducing the scrap rate of the overall parts and significantly reducing after-sales material and labor costs. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the end piece pretensioner provided in the embodiments of this application.

[0018] Figure 2 An exploded view of the end piece pretensioner provided in the embodiments of this application.

[0019] Figure 3 This is a schematic diagram of the cable and piston connection assembly provided in an embodiment of this application.

[0020] Figure 4 This is a schematic diagram of the structure of the guide plate provided in an embodiment of this application.

[0021] Figure 5 This is a schematic diagram of the assembly structure of the mounting plate and gas generator provided in the embodiments of this application.

[0022] In the diagram: End plate pretensioner 100, cable 1, screw 2, guide plate 3, rubber sealing assembly 4, mounting plate 5, step bolt 6, gas generator 7, piston seal ring 8, piston 9, locking ball 10, cable tail tube 11, cylinder power tube 12, sleeve 301, cable protection tube 302, mounting plate secondary chamber 501, mounting plate main chamber 502, cable guide tube 503. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that, in this invention, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0025] This invention provides an end-piece pretensioner for installation in a vehicle seatbelt restraint system. For example... Figures 1 to 5 As shown, the end plate pretensioner 100 includes: a cable 1, a screw 2, a guide plate 3, a rubber sealing assembly 4, a mounting plate 5, a stepped bolt 6, a gas generator 7, a piston sealing ring 8, a piston 9, a locking ball 10, a cable tail tube 11, and a cylinder power tube 12. The guide plate 3 includes a guide plate body, a sleeve 301 fixed on the guide plate body, and a cable protection tube 302 fixed on the sleeve 301. The mounting plate 5 is the main load-bearing component, and includes a mounting plate body and a mounting plate sub-chamber 501, a mounting plate main chamber 502, and a cable guide tube 503 disposed on the mounting plate body. The mounting plate main chamber 502 and the mounting plate sub-chamber 501 are internally interconnected. The gas generator 7 is fixedly installed in the mounting plate sub-chamber 501 by a riveting process. In one embodiment, the outer side of the mounting plate 5 is securely installed on the car frame or seat frame by step bolts 6 passing through fixing holes.

[0026] The mounting plate 5 has guide and actuator components of the gas actuation system connected to both ends. A guide plate 3 is fixedly mounted on one end face of the mounting plate 5 using several screws 2, and the guide plate 3 closes the port of the main chamber 502 of the mounting plate. The other end of the mounting plate 5 is fixedly connected to the cylinder working tube 12, and its interior communicates with the main chamber 502 of the mounting plate. The piston 9 is slidably arranged inside the cylinder working tube 12. A locking ball 10 is arranged on the arc-shaped outer wall of the piston 9, and a piston sealing ring 8 is fitted inside the outer circumferential groove of the piston 9, forming a sliding seal with the inner wall of the cylinder working tube 12.

[0027] The cable 1 passes through the guide plate 3, the rubber sealing assembly 4 and the main chamber 502 of the mounting plate in sequence, and then extends into the interior of the cylinder working tube 12. Inside the cylinder working tube 12, it passes through the piston 9 and is riveted to the cable tail tube 11. The end of the piston 9 is connected to the cable tail tube 11 through a conical surface fit. The cable tail tube 11 is used to transmit the huge pulling force generated on the cable 1 when the piston 9 slides backward.

[0028] like Figure 4 As shown, to address the risk of cable 1 being ablated by high-temperature, high-pressure gas in existing technologies, in one embodiment, the guide plate 3 employs a special deep-penetration structure. The sleeve 301 of the guide plate 3 is precisely inserted into the main chamber 502 of the mounting plate for precise positioning, and the protective tube 302 extends suspended from the sleeve 301 into the main chamber 502. The outer wall of the protective tube 302 is precisely positioned along the flow path of the gas generator 7 spraying towards the main chamber 502. This structure ensures that when the high-temperature propellant gas is ejected, it first impacts the outer wall of the protective tube 302, which acts as a physical barrier, preventing direct ablation of the cable 1 passing inside by the high-temperature gas.

[0029] To address the issue of air pressure leakage caused by seal failure in existing technologies, in one embodiment, the rubber sealing component 4 is embedded within the cable sheath 302. The inner wall of the end of the cable sheath 302 contracts inward to form an anti-disengagement snap-fit ​​flange, confining the rubber sealing component 4 within the cable sheath 302. Under normal conditions when the gas generator 7 is not activated, the rubber sealing component 4 and the cable 1 have a clearance fit, which does not affect the daily fine-tuning of the cable 1. When the gas generator 7 is activated and generates high-pressure gas, the high-pressure gas not only pushes the piston 9 backward but also compresses the rubber sealing component 4 within the cable sheath 302. Under extremely high pressure, the rubber sealing component 4 undergoes radial centripetal contraction deformation, gripping the surface of the cable 1, achieving a "dynamic high-pressure seal" where the clamping force increases with increasing gas pressure. Together with the piston sealing ring 8 behind it, this ensures the airtightness of the main chamber 502 of the mounting plate at the moment of explosion.

[0030] like Figure 5 As shown, to address the stress shearing problem at the cable bend, a cable guide tube 503 is integrally formed on the exterior of the mounting plate 5. After the cable 1, which exits the guide plate 3, is bent at a large angle, it passes through the cable guide tube 503 and is led outward to the actuator end such as the seat belt buckle. During the pre-tensioning stage, the cable 1 is subjected to extremely high tension instantaneously. At this time, the smooth inner wall of the cable guide tube 503 provides lateral support for the bent section of the cable 1, effectively unloading the acute angle shear stress borne by the cable 1 at the outlet of the central hole of the guide plate 3, and greatly reducing the risk of cable breakage or fracture.

[0031] The dynamic working principle of the end-plate pretensioner 100 is as follows: When a vehicle experiences a severe collision, the gas generator 7 receives an ignition signal from the vehicle's ECU and rapidly generates high-pressure gas. This high-pressure gas rushes from the mounting plate's secondary chamber 501 into the mounting plate's main chamber 502. After being blocked and refracted by the cable guard 302, the pressure forces the rubber sealing assembly 4 to radially contract and lock the front opening. Subsequently, the completely sealed burst force pushes the piston 9 to slide at high speed along the cylinder power tube 12 away from the mounting plate 5. The piston 9, through the locking ball 10 and the cable tail tube 11, pulls the cable 1 inward, thereby instantly tightening the seatbelt and firmly securing the occupant to the seat.

[0032] Furthermore, the connection between the guide plate 3 and the screw 2 constitutes a "partially replaceable module" to prevent accidental explosion. Even if the end plate pretensioner 100 accidentally explodes, or the internal rubber sealing component 4 ages, maintenance personnel only need to unscrew the screw 2 to slide the failed guide plate 3 and its embedded rubber sealing component 4 outward along the cable 1, replace it with a new guide plate 3 and piston 9, and then re-fix it. This design greatly reduces after-sales maintenance procedures and material costs.

[0033] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An end piece pretensioner, characterized in that, Includes cables, guide plates, rubber sealing components, mounting plates, gas generators, piston seals, pistons, locking balls, cable tailpipes, and cylinder power pipes; The mounting plate has a main chamber and a secondary chamber that are interconnected inside, and the gas generator is fixed in the secondary chamber. The guide plate is detachably mounted at one end of the mounting plate and seals the main chamber of the mounting plate; The rubber sealing assembly is embedded within the guide plate; The cylinder power tube is connected and fixed to the other end of the mounting plate, and its interior communicates with the main chamber of the mounting plate. The piston is slidably arranged inside the cylinder power tube, the piston sealing ring is sleeved on the outer periphery of the piston, and the locking ball is located in the middle of the piston; The cable tail tube is arranged at the end of the cable; The cable passes sequentially through the guide plate, the rubber sealing assembly, and the main chamber of the mounting plate, then extends into the cylinder working tube and passes through the piston, connecting to the cable tail tube at the end of the piston.

2. The end piece pretensioner according to claim 1, characterized in that, The guide plate includes a guide plate body, a sleeve, and a protective tube; The sleeve is located on the guide plate body, and the sleeve is used to be inserted into the main cavity of the mounting plate for mating and positioning. The protective tube is located on the sleeve and extends from the sleeve into the main cavity of the mounting plate. The rubber sealing assembly is embedded inside the protective tube.

3. The end piece pretensioner according to claim 2, characterized in that, When the high-pressure gas generated by the gas generator 7 is injected from the secondary chamber of the mounting plate into the main chamber of the mounting plate, the outer wall of the protective tube is positioned in the gas injection path to block the high-pressure gas.

4. The end piece pretensioner according to claim 2, characterized in that, The protective tube 302 The inner wall at the end furthest from the sleeve tapers inward to form an anti-loosening buckle flange; One end of the rubber sealing assembly is confined to the inside of the anti-disengagement buckle flange to prevent the rubber sealing assembly from coming out of the cable sheath under the impact of high-pressure gas and the pulling of the cable; When high-pressure gas enters the main chamber of the mounting plate, the rubber sealing assembly undergoes radial contraction deformation under the gas pressure, tightly gripping the cable surface to form a dynamic seal.

5. The end piece pretensioner according to claim 1, characterized in that, The mounting plate is provided with a cable guide tube on its exterior; The cable that passes through the guide plate bends and is led outward through the cable guide tube; During pre-tensioning and when the cable is under tension, the inner wall of the cable guide tube provides lateral support to the cable, unloading the shear stress on the cable at the center outlet of the guide plate.

6. The end piece pretensioner according to claim 5, characterized in that, The cable guide tube and the mounting plate are integrally formed.

7. The end piece pretensioner according to claim 1, characterized in that, When the end piece pretensioner is installed, the mounting plate is connected and fixed to the vehicle frame by fasteners.

8. The end piece pretensioner according to claim 1, characterized in that, The guide plate and the mounting plate work together to form a partially replaceable structure to prevent accidental explosions; When the end plate pretensioner is activated or an accidental explosion occurs, the guide plate can be removed from the mounting plate. Without cutting the cable, the guide plate, together with the embedded failed rubber sealing assembly 4, can be slid outward along the cable 1 as an independent module and replaced.

9. The end piece pretensioner according to claim 1, characterized in that, The central channel of the guide plate is not only used to accommodate the rubber sealing assembly, but its inner wall also provides radial guidance for the cable. The guide plate constrains the radial runout of the cable to ensure the coaxiality of the cable and the piston when they slide within the cylinder power tube, as the cable passes through the main cavity of the mounting plate.

10. An end piece pretensioner according to any one of claims 1-9, characterized in that, When the gas generator receives the ignition signal, it quickly generates high-pressure gas. The gas enters the main chamber of the mounting plate and, under the sealing barrier of the rubber sealing assembly and the piston sealing ring, pushes the piston to slide in the cylinder power tube, thereby driving the cable to pull through the locking ball and the cable tail tube.

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