Safety device inside the vehicle

Abstract

Provide a safety device that enables easy pushing back of the piston towards the retracted position. 【Solution means】The safety device (100) includes a housing (1) having a first end (2) and a second end (3), a piston (4) fitted therein, and a gas generator (15). The piston (4) has a first end that forms a pressure surface (6) facing the first end of the housing (1). A gas chamber (8) is formed between the pressure surface (6) of the piston (4) and the inner wall (7) of the housing (1), and the gas generator (15) is in the gas chamber (8). The housing (1) includes a gas discharge configuration (20) at its second end (3), whereby when the piston (4) is in a fully or substantially fully extended position, the gas generated by the gas generator (15) is discharged from the gas chamber (8).

Description

Technical Field

[0001] The present invention relates to a safety device in a vehicle.

Background Art

[0002] It is well known in the art to use an actuator formed by a piston that is moved from a retracted position to an extended position by gas generated by a gas generator in a safety device within a motor vehicle. One example is the use of a hood lifter that raises the hood or bonnet of a vehicle to provide protection to a pedestrian struck by the vehicle. It has been observed that when a motor vehicle strikes a pedestrian, the vehicle bumper often strikes the pedestrian's leg or lower torso. Thus, the pedestrian's leg is typically pushed in the direction of vehicle travel, and the head and upper torso typically tilt towards the vehicle hood and windshield. This tilting motion often first brings the pedestrian's head or upper torso into contact with the hood, and then, if the impact force from the collision is strong enough and the vehicle continues to move forward, also reaches the windshield. To minimize pedestrian injuries caused by impacts such as those described above, motor vehicles are often provided with so-called hood lift configurations. These configurations are generally arranged such that the rear portion of the hood, i.e., the portion closest to the windshield, is lifted by one or more actuators. The hood generally provides an efficient and flexible impact energy absorption structure when the vehicle strikes a pedestrian. However, if the hood is not lifted, there is a high risk that the hard, non-flexible portion under the hood, such as the engine block, will contact the hood and deform the hood to such an extent that an undesirable hard impact results from the collision between the pedestrian and the vehicle. In addition, the raising of the rear portion of the hood further inclines the surface of the hood and contributes to reducing the speed of an object moving towards the windshield. In addition, the more gradual angle between the windshield and the hood also contributes to reducing the critical condition of a person struck by the vehicle.

[0003] To provide efficient protection, it is essential that the lifting be carried out quickly. However, it is also necessary to be able to handle the vehicle easily after an accident, for example, if possible, drive the vehicle to the nearest garage or be able to tow the vehicle in a safe manner. This requires that the hood can be pushed back manually to enable a free view from the driver's seat. This is accompanied by the requirement that the force required to push the piston back towards its retracted position should not be too high. For this purpose, it is known to have a vented gas chamber with a vent hole arranged at the bottom end of the housing, i.e., on the opposite side of the pressure surface of the piston. However, such venting causes an undesirable leaking flow of the generated gas, thereby causing the problem that the setting of the piston from the retracted position to the extended position is delayed. Therefore, an improved actuator is needed that enables a more powerful and rapid setting and easy pushing back of the piston during the operation of the actuator. This type of actuator can also be used in other safety systems for vehicles, such as seat belt pretensioners, and in such applications, it is important to have high-speed operation. SUMMARY OF THE INVENTION

[0004] An object of the present invention is to provide a safety device in a vehicle that enables the piston to be set more quickly from its retracted position to its fully extended position during the deployment of the gas generator and thus during the operation of the safety device.

[0005] Another object of the present invention is to provide a safety device that enables easy pushing back of the piston towards the retracted position.

[0006] These and other objects, which will become apparent from the following summary and description, are a safety device in a vehicle, the safety device comprising a housing having a first end and a second end, a piston adapted to fit within the housing and configured to move from a retracted position to an extended position, and a gas generator. The piston has a first end that forms a pressure surface facing the first end of the housing, A gas chamber is formed between the pressure surface of the piston and the inner wall of the housing, and a gas generator is fluidly connected to the gas chamber. The housing comprises a gas discharge arrangement at its second end, which enables the gas generated by the gas generator to be discharged from the gas chamber in a state where the piston is in a fully or substantially fully extended position, achieved by a safety device.

[0007] Accordingly, there is provided a safety device in which substantially all of the gas generated by the gas generator during deployment is used to push the piston to its extended position. Gas discharge is only possible when the piston is in its extended position. This provides a faster and stronger setting of the piston to its fully extended position compared to prior art solutions where a vent hole is arranged in the gas chamber in the bottom end of the housing on the opposite side of the pressure surface of the piston that already has a leaking gas flow from the start of deployment of the gas generator. In practice, the faster setting results in earlier protection regardless of whether the item is a pedestrian who has been hit or a seat belt to be pulled. When the safety device is a seat belt pretensioner, a faster latching of the person in the vehicle seat is provided, thereby restricting movement of the body forward. According to the present invention, the gas generated by the gas generator can escape from the gas chamber via the gas discharge arrangement when the piston is set in its fully or substantially fully extended position, and only at that position can the pressure in the gas chamber be reduced to the same pressure as the ambient pressure. Accordingly, there is no positive gas pressure that has to be overcome when pushing the piston back after actuation.

[0008] The gas discharge configuration may include a through-opening in the side wall of the housing. The number of openings can be one or two or more. The more the number of openings, the faster the gas discharge. In the case of two or more openings, the openings can be displaced from each other in the axial extension of the housing. Also, the openings can have different sizes.

[0009] One or more openings are arranged in a region adjacent to the upper end of the housing, so that a free passage for the generated gas is formed only when the piston is axially displaced to such an extent that the piston reaches its fully or substantially fully extended position.

[0010] The through-opening may be provided with a sealing such as a check valve or a membrane configured to rupture by the gas pressure generated by the gas generator. By providing a seal for the opening, moisture or dust is prevented from entering the inside of the safety device over time during normal use of the vehicle.

[0011] The gas discharge configuration may extend axially and have a recess that projects radially outward. The recess is configured such that when the piston is in its fully or substantially fully extended position, the gas generated by the gas generator can bypass the piston axially.

[0012] By forming the gas discharge configuration as a recess that projects radially outward, the bypass channel is formed only when the piston is axially displaced to such an extent that the piston reaches its fully or substantially fully extended position.

[0013] The piston may be provided with a circumferential seal ring arranged axially at the same height as the recess when the piston is in its fully or substantially fully extended position. Thereby, the volume near the seal ring is added to the volume of the recess, thereby increasing the volume of the bypass flow path.

[0014] The recess may have an axial extension that exceeds the axial extension of the sealing ring.

[0015] In one embodiment, the recess may have a circumferential extension. In an alternative embodiment, the recess may have an intermittent circumferential extension or may be formed by one or more separate recesses.

[0016] The safety device may be a hood lifter within a vehicle.

[0017] The safety device may be a seat belt pretensioner within a vehicle.

[0018] The safety device may be a seat structure reinforcement.

Brief Description of the Drawings

[0019] The present invention will be described in detail with reference to schematic diagrams.

[0020]

Figure 1a

Figure 1b

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0021] Referring now to FIG. 1a, a schematic cross-sectional view of one embodiment of the safety device 100 is disclosed. The safety device 100 is shown in a state where its piston is in a fully retracted position.

[0022] The safety device 100 includes a housing 1 in the form of a hollow cylinder having a first end 2 and a second end 3. The housing 1 can be formed of a deep-drawn metal material. The first end 2 is a closed end. The housing 1 includes a piston 4. The piston 4 is shown as having a portion 5 that extends out of the housing 1 through the second end 3 of the housing 1. It should be understood that the piston 4 having the remaining functions of the present invention can be of a type in which the piston 4 is completely received within the housing 1 when the piston 4 is in its fully retracted position.

[0023] The piston 4 is fitted within the housing 1. The piston 4 is axially movable within the housing 1 from a retracted position to a fully or substantially fully extended position. The retracted position is the default position of the piston 4. The piston 4 has a pressure surface 6 facing the first end 2 of the housing 1. The pressure surface 6 typically has an outer cross-sectional area and an outer cross-sectional shape that substantially correspond to the inner cross-sectional area and the inner cross-sectional shape of the housing 1. Thereby, the inner wall 7 of the housing 1, together with the pressure surface 6 of the piston 4, defines a gas chamber 8. The volume of the gas chamber 8 is variable depending on the instantaneous axial position of the piston 4 within the housing 1. The gas chamber 8 has a minimum volume when the piston 4 is in its fully retracted position and has its maximum volume when the piston 4 is in its fully extended position.

[0024] The circumferential surface 9 of the piston 4 supports a sealing ring 10 that seals against the axial portion of the inner wall 7 of the housing 1. The sealing ring 10 is received in a circumferential recess 11 of the circumferential surface 9 of the piston 4.

[0025] The end 12 of the housing 1 adjacent to the second end 3 of the housing 1 is provided with a neck portion 13 having a locally reduced cross-sectional area. The edge 14 of the piston 4 on the opposite side of the pressure surface 6 is configured to abut against the end 12 in a state where the piston is set in its fully extended position (see Fig. 1b). Thereby, a physical stop is formed to prevent the piston 4 from dropping out of the housing 1.

[0026] The safety device 100 further comprises a gas generator 15. The gas generator 15 is located in the gas chamber 8. The gas generator 15 is disclosed as being received in a recess 16 extending in the axial direction of the piston 4 and thus supported by the piston 4 in the disclosed embodiment. In an alternative solution (not shown), the gas generator 15 may be arranged adjacent to the first end 2 of the housing 1. Thus, the gas generator 15 must not be supported by the piston 4. Regardless of the position of the gas generator 15, the gas chamber 8 is defined by the inner wall 7 of the housing 1, the pressure surface 6 of the piston 4, and the gas generator 15.

[0027] The gas generator 15 is directly or indirectly connected to the schematically disclosed power connector 17. The power connector 17 is arranged outside the housing 1 supported by the portion 5 of the piston 4 extending out of the housing 1 in the disclosed embodiment. The power connector 17 is designed to communicate with the gas generator 15 and supply power to the gas generator 15 via a conductive wire configuration 18 along the axial extension of the piston 4 and thus extending into the housing 1 in this embodiment.

[0028] If the gas generator 15 is to be arranged adjacent to the first end 2 of the housing 1 instead, the power connector 17 may be arranged on the first end 2 of the housing 1 and communicate with the gas generator 15 through an opening in the first end 2 of the housing 1 to supply power to the gas generator 15.

[0029] The power connector 17 is configured to be connected to an electronic control unit (ECU) (not shown) of a vehicle in a manner well-known in the art, regardless of position. When the ECU determines, via a crash sensor and a processor integrated into the ECU, that there is an emergency situation to be reacted to, such as a frontal collision with a pedestrian or a cyclist, an activation signal is communicated to the ignition device of the gas generator 15, and this gas generator deploys the ignition device. Next, the gas generator 15 generates a gas volume having a pressure substantially higher than the ambient pressure. The gas acts on the pressure surface 6 of the piston 4 and axially moves the piston 4 from its retracted position to its extended position (see Fig. 1b).

[0030] Referring now to Fig. 2, a first embodiment of the gas discharge configuration 20 of the present invention will be discussed. The gas discharge configuration 20 is disposed at the second end 3 of the housing 1. The overall purpose of the gas discharge configuration 20 is to enable the gas generated by the gas generator 15 to be discharged from the gas chamber 8 in a state when the gas generator is deployed. By this gas discharge, the gas pressure inside the gas chamber 8 is reduced to a level corresponding to the ambient pressure. The gas discharge configuration 20 is disposed at an axial position within the housing 1, such that a free passage for only the generated gas is formed when the piston 4 is axially displaced to such an extent that the piston 4 reaches its fully or substantially fully extended position.

[0031] In the first embodiment of FIG. 2, the gas discharge configuration 20 is disclosed as a through-opening 21 disposed in the side wall 7 of the housing 1. The number of through-openings 21 can be one or two or more. The greater the number of openings 21, the faster the gas discharge. One or more openings 21 are disposed in a region adjacent to the second end 3 of the housing 1, such that when the piston is axially displaced to such an extent that the piston 4 reaches its fully or substantially fully extended position, a free passage for only the generated gas is formed. At this position, the sealing ring 10 of the piston 4 at least partially passes through the through-opening 21, thereby enabling the gas chamber 8 to communicate with the surroundings via at least one opening 21. In the disclosed embodiment, the sealing ring 10 completely passes through the opening 21. One skilled in the art will understand that a passage through the opening 21 is formed when the sealing ring 10 reaches the edge 22 of the opening 21, and then, as the piston 4 moves to the fully extended position shown in FIG. 2, the size of the passage gradually increases until it corresponds to the entire cross-sectional area of the opening 21.

[0032] In the case of two or more openings 21, these openings can be displaced axially and / or circumferentially. The greater the number of openings, the faster the gas discharge. In the case of two or more openings, the openings can have different cross-sectional areas.

[0033] A seal 22 can be provided in the through-opening 21. The seal 22 is schematically illustrated by a dashed line. The seal can be a check valve or a membrane. In the case of a membrane, the membrane is configured to rupture by the gas pressure generated by the gas generator 15. By providing the seal 22 in the opening 21, moisture or dust is prevented from entering the inside of the housing over time during normal use of the vehicle.

[0034] Referring now to FIG. 3, a second embodiment of the gas discharge configuration 20' is disclosed. The gas discharge configuration 20' includes a recess 23 that extends axially and projects radially outward. The recess 23 is configured such that the gas generated by the gas generator 15 can bypass the piston 4 axially only when the piston 4 is in a fully or substantially fully extended position.

[0035] The recess 23 has an axial extension in the housing 1, such that a bypass channel 24 is formed only when the piston 4 is axially displaced to a fully or substantially fully extended position where the seal ring 10 of the piston 4 at least partially passes through the recess 23.

[0036] The circumferential seal ring 10 of the piston 4 is preferably disposed at the same axial height as the recess 23 when the piston 4 is in a fully or substantially fully extended position. The recess 23 may have an axial extension that exceeds the axial extension of the seal ring 10.

[0037] The recess 23 is disclosed as a single discrete recess. In an alternative embodiment, the recess may have a continuous circumferential extension. In another embodiment, the recess may have an intermittent circumferential extension. Also, two or more recesses may be disposed along the axial extension of the housing 1.

[0038] Referring now to FIG. 4, a third embodiment is disclosed, in which the gas discharge configuration 20'' includes a combination of a through opening 21 and a recess 23 extending axially and protruding radially outward. The opening 21 and the recess 23 are of the same type as those described above. The recess 23 is disclosed as being disposed closer to the second end 3 of the housing 1 than the opening 21. When the piston 4 reaches its fully extended position, the gas generated in the gas chamber 8 can be discharged from the gas chamber both radially through the through opening 21 and axially through a bypass channel 24 passing through the recess 23. The combination of the opening 21 and the recess 23 allows for very rapid gas discharge.

[0039] Referring now to FIGS. 5 and 6. FIG. 5 discloses a safety device 100 set in its fully extended position, with the gas chamber 8 filled with gas, and when the piston is in its fully or substantially fully extended position, the gas is discharged by the gas discharge configurations 20, 20', 22'' at the second end 3 of the housing 1 immediately below the piston. When the internal pressure has dropped to a level substantially corresponding to the ambient pressure, the piston 4 can then be pushed back to its retracted position (see FIG. 6). This is done by applying an axial pressure F to the piston 4, thereby pushing the piston back into the housing. Since the gas has been discharged to a level where the pressure difference between the inside of the housing 1 and the outside is substantially reduced, the required pressure is very low and the push-back can in most cases be done manually.

[0040] This is useful, for example, when the safety device is a hood lifter. The hood lifter is typically arranged at the rear of the vehicle hood adjacent to its windshield. In the event of an accident, the hood lifter lifts the rear end of the hood, thereby protecting, for example, the body of a pedestrian who has collided with the vehicle. The safety device can alternatively be a seat belt pretensioner. The seat belt pretensioner can be configured to apply a tensile force to the seat belt in the event of an accident, thereby providing early engagement of the body sitting on the seat. Alternatively, the safety device can be a seat structure reinforcement that provides a lifting force to the seat structure in the event of an accident.

Claims

1. A safety device within a vehicle, the safety device comprising a housing (1) having a first end (2) and a second end (3), a piston (4) adapted to fit within the housing (1) and configured to move from a retracted position to an extended position, and a gas generator (15). The piston (4) has a first end that forms a pressure surface (6) facing the first end (2) of the housing (1). A gas chamber (8) is formed between the pressure surface (6) of the piston (4) and the inner wall (7) of the housing (1), and the gas generator (15) is fluidly connected to the gas chamber (8). The housing (1) comprises a gas discharge configuration (20, 20', 20'') at its second end (3), which enables the gas generated by the gas generator (15) to be discharged from the gas chamber (8) when the piston (4) is in a fully or substantially fully extended position. A safety device.

2. The safety device according to claim 1, wherein the gas discharge configuration (20, 20', 20'') comprises a through-opening (21) in the side wall of the housing (1).

3. The safety device according to claim 2, wherein the through-opening (21) is provided with a sealing (22), such as a check valve or a membrane, configured to rupture by the gas pressure generated by the gas generator (15).

4. The gas discharge configuration (20, 20', 20'') extends axially and comprises a recess (23) that protrudes radially outward. The recess (23) is configured to enable the gas generated by the gas generator (15) to bypass the piston (4) axially when the piston (4) is in a fully or substantially fully extended position. The safety device according to claim 1.

5. The piston (4) comprises a circumferential sealing ring (10), and the sealing ring (10) is arranged at the same axial height as the recess (23) when the piston (4) is in the fully or substantially fully extended position. The safety device according to claim 4.

6. The safety device according to claim 5, wherein the recess (23) has an axial extension exceeding the axial extension of the sealing ring (10).

7. The safety device according to claim 4 or 5, wherein the recess (23) has a circumferential extension or the recess (23) has an intermittent circumferential extension.

8. The safety device according to claim 1 or 2, wherein the safety device is a hood lifter in a vehicle.

9. The safety device according to claim 1 or 2, wherein the safety device is a seat belt pretensioner in a vehicle.

10. The safety device according to claim 1 or 2, wherein the safety device is a seat structure reinforcement.

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