Seatbelt tensioner for a motor vehicle's seatbelt system

Abstract

Belt tensioner (27) for a safety belt system of a motor vehicle, comprising - at least one electric actuator (12), wherein - a decentralized, self-sufficient electrical energy storage device (20) is assigned to the belt tensioner (10), which is designed to store a sufficient amount of electrical energy for the operation of the actuator (12), characterized in that the energy storage device (20) can be recharged by activating an electromechanical force limiter in generator mode, wherein the energy charged after the force-limited belt extension is subsequently used to trigger an emergency call or a warning signal.

Description

[0001] The present invention relates to a belt tensioner for a safety belt system of a motor vehicle, comprising at least one electric actuator.

[0002] Seat belt systems are no longer purely mechanical products. In addition to mechanical components, they can contain pyrotechnic, electronic, and / or electromechanical components. Modern reversible belt tensioners, regardless of their installation point (in the retractor, buckle, or end fitting), are capable of reducing belt slack in critical driving situations, thus restraining the occupant at an early stage. Such reversible belt tensioners for seat belt systems are well known in the prior art; see, for example, DE 44 11 184 C2 and DE 100 29 061 A1. One function of a reversible belt tensioner is to reduce existing belt slack in the seat belt system in a situation where an accident might occur, also known as the pre-crash phase, in order to engage the occupant as early as possible in a potential subsequent collision and thus decelerate the vehicle as quickly as possible.This distributes the occupant load over the longest possible path of forward movement, thus reducing the maximum occupant load. Furthermore, reversible seatbelt pretensioners can also serve as a warning system to alert the occupant to a dangerous situation.

[0003] If no accident occurs after the pre-impact phase, the seatbelt pretensioner is deactivated and the belt force is reduced. For this reason, it is important that the seatbelt pretensioner operates reversibly. Reversible seatbelt pretensioners can, for example, have an electric motor drive, which is particularly easy to control and operates without any time delay.

[0004] In general, reversible seatbelt pretensioners can effectively prevent forward movement from the design position. The reaction time is on the order of a few milliseconds. Due to this short reaction time and the required mechanical work, a certain amount of electrical energy is needed.

[0005] In general, several questions arise with seatbelt pretensioners that have one or more electric actuators: i) How can the required electrical energy be supplied to the actuator quickly? The following points also play a role: in motor vehicles, small conductor cross-sections are desirable to reduce weight; the distance between the vehicle battery or generator and the actuator must also be considered; if the seatbelt pretensioner is installed in a vehicle seat, there is a detachable electrical connection point.ii) How can the power supply be ensured in the event of an accident if there is a risk that the alternator and / or vehicle battery will be damaged shortly after impact (e.g., by a short circuit) and / or disconnected for safety reasons by means of a safety switch and / or disconnected supply lines or connectors? iii) How can the required energy be provided if the vehicle electrical system voltage is at its lower limit or if many electrical consumers are drawing power from the system simultaneously? The following points also play a role: a small alternator is desirable in motor vehicles to save weight; the vehicle battery may be weak, for example, in winter or due to age, or its capacity may be at its reserve; shortly before an accident situation is detected (time t0), high-current consumers such as ESC (Electronic Stability Control), reversible seatbelt pretensioners, seat adjustment, power windows, etc., are simultaneously drawing power.which places a particular strain on the vehicle battery.

[0006] DE 10 2017 212 975 discloses a seatbelt tensioner according to the preamble of claim 1.

[0007] DE 10 2011 016 615 A1 discloses a safety belt device in which the force limiting unit is designed as an electric machine that acts on the one hand as an electric motor and on the other hand as a generator.

[0008] DE 10 2018 219 040 A1 discloses a belt retractor in a coaxial design.

[0009] The object of the invention is to ensure reliable actuation of the electric actuator in every possible situation.

[0010] The invention solves this problem with the features of the independent claims. According to the invention, a decentralized, self-sufficient electrical energy storage device is associated with the seatbelt tensioner, which is designed to store a sufficient amount of electrical energy for the operation of the actuator. Decentralized means that the electrical energy storage device is provided in addition to the vehicle battery and is located at or in the vicinity of the seatbelt tensioner. Self-sufficient means that the electrical energy storage device is independently functional and provides electrical energy regardless of the state of the vehicle battery or of supply lines between the vehicle battery and the seatbelt system.

[0011] The solution according to the invention consists of a decentralized, self-sufficient, and preferably diagnosable energy storage device as an energy source, which is advantageously placed at the actuator. This can be a battery, a rechargeable battery, or a capacitor, which can provide the required energy for various load cases. Preferably, the energy storage device comprises at least one supercapacitor, ultracapacitor, double-layer capacitor, or, more generally, an electrochemical capacitor, in order to store the required amount of energy in a small installation space. The use of at least one high-voltage capacitor with a nominal voltage of at least 100 V, preferably at least 200 V, and more preferably at least 300 V, is advantageous, since high-voltage capacitors generally require less installation space.For use as a high-voltage capacitor or more generally for the electromagnetic shielding of the energy storage device's interior (Faraday cage) and its surroundings, it can be advantageous for the energy storage device to be encased in a metallic housing. However, a plastic housing for the energy storage device is also possible for the sake of simpler electrical insulation.

[0012] The application, the required energy quantity, and the internally used voltage determine the energy storage volume needed for the electrical energy. For example, a considerable amount of energy is required to tighten the belt system, similar to a pyrotechnic tightening process. Therefore, the energy storage device is preferably designed to store at least 100 J, more preferably at least 150 J, and even more preferably at least 200 J, at least 1000 J, at least 1500 J, or at least 2000 J. The installation location and the actuator used then determine the design and installation position of the energy storage device.

[0013] In preferred embodiments, the at least one electric actuator comprises an electric motor, which is advantageously configured for reversible pretensioning and / or power tensioning of the seat belt. In some embodiments, the energy storage device can serve to supply an electromechanical force limiter. Preferably, the energy storage device is configured to store a sufficient amount of electrical energy to perform one or more of the following functions: reversible belt pretensioning in a pre-accident situation; power tensioning in the event of an unavoidable vehicle impact; electromechanical force limiting. These functions are briefly explained below.

[0014] Reversible belt pretensioning is performed when a critical driving situation or an impending collision is detected, but it is still unclear whether a collision will occur. In this situation, belt slack is pre-tensioned as a precaution to better restrain the occupant and prevent movement from the intended position. This facilitates any subsequent performance tightening, as it can begin from a pre-tensioned position. If it turns out that a collision was avoided, the belt pretensioning is released, and the seat belt is once again freely extendable.

[0015] The belt tensioner according to the invention can be advantageously used in various applications. One preferred application relates to a belt retractor. In some embodiments, the belt retractor is designed and configured for installation in a vehicle seat, particularly in its backrest. In this case, it can be advantageous, due to space constraints, if the belt spool, a force limiter, a gearbox, and the electric motor are arranged coaxially to each other in the belt retractor to form a continuous longitudinal axis A.

[0016] Other possible applications for the belt tensioner according to the invention include its arrangement in a belt buckle as a so-called buckle tensioner or its arrangement on an end fitting as a so-called end fitting tensioner.

[0017] Advantageously, the electrical energy storage device serves exclusively to supply energy to the electrical components and actuators of the seatbelt pretensioner, the seatbelt system, or an occupant restraint system, including airbags, but not to supply energy to electrical components and actuators of other vehicle systems. This has the advantage that energy is not drawn by other vehicle systems, and all the energy stored in the electrical energy storage device is available to the seatbelt pretensioner / seatbelt system / occupant restraint system.

[0018] According to the invention, the energy storage device can be recharged by activating an electromechanical force limiter in generator mode, so that the energy storage device is at least partially charged with energy after the force-limited extension of the webbing. This energy is subsequently used to trigger an emergency call or a warning signal.

[0019] The invention is explained below with reference to preferred embodiments and the accompanying figures. Fig. 1 a seatbelt retractor for a vehicle seat with a seatbelt tensioner according to the invention in a first embodiment; Fig. 2 a seatbelt retractor for a vehicle seat with a seatbelt tensioner according to the invention in a second embodiment; Fig. 3 a belt retractor for the B-pillar with a belt tensioner according to the invention in a third embodiment; and Fig. 4 a belt retractor for the B-pillar with a belt tensioner according to the invention in a fourth embodiment.

[0020] The embodiments according to Fig. 1 and Fig. 2 relate to a belt retractor 10 for mounting on or in a vehicle seat, in particular on a support, for example a cross member, in the backrest of a vehicle seat.

[0021] The seat belt retractor 10 comprises a vehicle-mounted housing 13 with vehicle-mounted support elements 18, 19, which include, for example, crossbeams 18, and attachment points 30 for attaching the seat belt retractor 10 to the vehicle structure. The seat belt retractor 10 includes a belt spool 11 rotatably mounted in the housing 13 or a U-shaped support element 19, onto which an occupant safety belt (not shown) can be wound. The belt spool 11 is rotationally fixed to a coaxial belt shaft 14.

[0022] The belt retractor 10 further comprises a belt tensioner 27 with an electric motor 12 for rotating the belt shaft 14 and thus the belt reel 11. The motor shaft 15 of the electric motor 12 is connected to a gearbox 16, which transmits the rotary motion of the motor shaft 15 to the belt shaft 14. Functionally located between the gearbox 16 and the belt reel 11 is a force limiter 17, which limits the force exerted on the occupant by the seat belt in the event of a vehicle impact. The force limiter 17 can, for example, contain a torsion bar or be based on another operating mechanism.

[0023] The belt spool 11, the force limiter 17, the gearbox 16 and the electric motor 12 are advantageously arranged coaxially to each other (see Fig. 1 and Fig. 2), so that the overall elongated belt retractor 10 extends along a continuous longitudinal axis A, which runs centrally through the belt shaft 11 and the motor shaft 15. This arrangement is particularly suitable for mounting on a fixed support, for example a cross member in the backrest of a vehicle seat.

[0024] The electric motor 12 is configured to perform one or more of the following functions: reversible belt pretensioning in a pre-accident situation; power tensioning in the event of an unavoidable vehicle impact; electromechanical force limitation. These functions have already been explained. It is also conceivable to selectively provide the stored energy for individual functions, for example, situation-dependently for power tensioning or force limitation. To perform these functions, the belt retractor 10 advantageously has a digital electronic control unit 19, which, for example, includes a microprocessor or microcontroller and is advantageously connected to the vehicle bus via a signal line 21. A diagnostic signal with data on the charge and / or wear status of the energy storage device 20 can also be sent to an electronic control unit of the vehicle via the signal line 21.In this way, the energy storage device 20 can be advantageously diagnosed, and, for example, in the event of wear and tear of the energy storage device 20, appropriate measures can be taken. Diagnostic data from the energy storage device can be transmitted to the control unit 19 via line 24, which can be advantageous for charging control.

[0025] The seatbelt retractor 10 is associated with an energy storage device 20, which is dimensioned to store a sufficient amount of energy to perform all intended functions of the electric motor 12 (reversible seatbelt pretensioning, power tensioning, etc.) without any further external energy supply, in particular without energy supply from the vehicle battery. For example, if a pre-accident trigger signal is received via the bus line 21, the control unit 19 activates the electric motor 12 to perform the reversible seatbelt pretensioning, with the required electrical energy being supplied via an electrical supply line 24, which connects the electric motor 12 directly or indirectly to the energy storage device 20 via the control unit 19. The same applies if, for example, an accident trigger signal is received by the control unit 19 via the bus line 21.In a pre-accident or accident situation, the function of the belt tensioner 10 is therefore ensured in any case, even if the supply line 22 from the vehicle battery 23 should be interrupted or the vehicle battery 23 is overloaded or fails for other reasons.

[0026] The energy storage device 20, for example a supercapacitor, is preferably dimensioned and configured to store an energy quantity of at least 100 J, preferably at least 150 J, more preferably at least 200 J, and even more preferably 1000 J, 1500 J, or 2000 J. The energy storage device 20 is preferably part of the belt retractor 10 and / or arranged within the housing 13. The energy storage device 20 can also be arranged outside the housing 13 and / or be a separate component from the belt retractor 10.

[0027] The energy storage device 20 can preferably be enclosed in a metal housing 26. This allows the use of high-voltage capacitors with 100 V or more, which advantageously further reduces the volume of the energy storage device 20. Further advantages of a metallic housing 26 include electrical shielding of the interior of the energy storage device 20 (Faraday cage) and the environment. Grounding of a metallic housing 26 can be advantageous. Designs with a housing 26 made of plastic or a combination of metal and plastic housings are possible, which facilitates simple electrical insulation.

[0028] The control unit 19 advantageously includes an electronic charging controller connected to the vehicle battery 22 via a supply line 25. The charging controller ensures the charging of the energy storage device 20 when its state of charge is low or has fallen below a certain threshold. Furthermore, a transformer can be provided to convert the vehicle's on-board voltage to the charging voltage for the energy storage device 20. This allows for a charging cycle with a lower current during normal vehicle operation. An intelligent charging mode can also be provided, in which the charging process is interrupted in critical situations and then resumed during normal operation once the critical situation has ended. The energy storage device is coupled to an electromechanical force limiter; activation of the electromechanical force limiter is used to charge the energy storage device 20.This charging takes place while the occupant is restrained in the accident or during the force-limited forward movement of the occupant in the accident and is subsequently used after the accident has ended to send an emergency call or a warning signal.

[0029] In the embodiment according to Fig. 1 The energy storage device 20 is elongated, for example cylindrical, and advantageously arranged axially parallel to the longitudinal axis A of the belt winder 10, for example below the shaft axis 14, 15. In order to be able to use a relatively thin energy storage device 20 (i.e. with a relatively small diameter) due to space constraints, the energy storage device 20 can preferably comprise several smaller, for example cylindrical, storage units 23 arranged in series along a longitudinal axis of the energy storage device 20, as in Fig. Figure 1 shows that the energy storage device 20 can advantageously be held on one or more crossbeams 18. The retractor / retractor 10 and the energy storage device 20 could advantageously be placed within the upper crossbeam of a vehicle seat, thus providing, for example, sufficient space for the occupant to slide through in the event of a rear-end collision.

[0030] In the embodiment according to Fig. In this embodiment, the energy storage device 20 is, for example, cylindrical and advantageously arranged radially, transversely, obliquely, or at an angle to the longitudinal axis A of the belt retractor 10. In this embodiment, the energy storage device 20 is, for example, a separate component and can be arranged, for example, in or on the side support of a vehicle seat backrest.

[0031] The embodiments according to Fig. 3 and Fig. Section 4 relates to an application with a retractor 10, particularly for installation in the B-pillar of the vehicle. Here, an arrangement of the energy storage device 20 parallel to the shaft axis A is suitable ( Fig. 3) above or below the belt reel 11, depending on where the actuator (electric motor 12) is located, because the installation space in the B-pillar is very limited in the x and y dimensions. The design of the B-pillar may also necessitate an installation with a separate energy storage unit 20, as shown in Fig. 4 shown. Also an arrangement perpendicular or radial to the shaft axis A as in Fig. 4 is possible.

[0032] The figures describe an energy storage device 20 for operating an electric motor 12 in a seatbelt retractor 10. Corresponding applications are possible in a seatbelt buckle tensioner or an end fitting tensioner of a seatbelt system.

Claims

[1] Belt tensioner (27) for a seat belt system of a motor vehicle, comprising - at least one electric actuator (12), wherein - the belt tensioner (10) is assigned a decentralized, self-sufficient electrical energy storage device (20) which is designed to store a sufficient amount of electrical energy for the operation of the actuator (12), characterized by , that the energy storage device (20) can be recharged by activating an electromechanical force limiter in generator mode, wherein the energy charged after the force-limited belt extension is subsequently used to trigger an emergency call or a warning signal. [2] Seatbelt tensioner (27) according to claim 1, characterized by , that the energy storage device (20) comprises a battery, an accumulator and / or a capacitor, in particular a supercapacitor. [3] Seatbelt tensioner (27) according to any of the preceding claims, characterized by, that the energy storage device (20) includes at least one high-voltage capacitor with a nominal voltage of at least 100 V. [4] Seatbelt tensioner (27) according to any of the preceding claims, characterized by , that the energy storage device (20) is designed to store an energy quantity of at least 100 J. [5] Seatbelt tensioner (27) according to any of the preceding claims, characterized by , that the at least one electric actuator (12) comprises an electric motor. [6] Belt tensioner (27) according to claim 5, wherein the electric motor (12) is configured for reversible pre-tensioning and / or performance tensioning of the seat belt. [7] Seatbelt tensioner (27) according to any of the preceding claims, characterized by that at least one electrical actuator is part of an electromechanical force limiter. [8] Seatbelt tensioner (27) according to any of the preceding claims, characterized by, that the energy storage device (20) is designed to store a sufficient quantity of electrical energy to perform one or more of the following functions: - Reversible seatbelt pretensioning in a pre-accident situation; - Performance reduction in the event of an unavoidable vehicle collision; - electromechanical force limitation. [9] Seatbelt tensioner (27) according to any of the preceding claims, characterized by that the energy storage device (20) has a metallic casing (26). [10] Seatbelt retractor (10), comprising - a belt spool (11) rotatably mounted in a vehicle-mountable housing, onto which a safety belt can be wound; and - a belt tensioner (27) according to any of the preceding claims. [11] Belt retractor (10) according to claim 10, characterized by , that the belt retractor (10) is designed and configured for arrangement in a vehicle seat. [12] Belt retractor (10) according to claim 10 or 11, characterized by , that the belt spool (11), a force limiter (17), a gearbox (16) and the electric motor (12) are arranged coaxially to form a continuous longitudinal axis A. [13] Buckle for a seat belt system in a motor vehicle, characterized by , that the seat belt buckle has a seat belt tensioner (27) according to one of claims 1 to 9. [14] Seat belt end fitting for a seat belt system in a motor vehicle, characterized by , that the end fitting has a belt tensioner (27) according to one of claims 1 to 9.

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