Force transmission element and device for tensioning a seat belt having a force transmission element

Abstract

According to the present invention, a force transmission element for a device for tensioning a safety belt is provided, wherein the force transmission element is a rod-shaped body which is structured substantially over its entire length and / or is formed at least by a first part and a second part.

Description

Field of the Invention

[0001] The present invention relates to a force transmission element for a device for tensioning a seat belt and a device for tensioning a seat belt having such a force transmission element. Background Art

[0002] Devices for tensioning seat belts or seat belt tensioners, like airbags, belong to the so-called passive safety systems of a vehicle. The purpose of a seat belt tensioner is to tension the seat belt in the event of an accident so that the vehicle occupant is involved in the overall deceleration of the vehicle earlier. For this purpose, the seat belt is retracted by up to 15 cm in about 10 to 15 milliseconds.

[0003] The seat belt tensioner can either be integrated in the seat belt retractor, below the seat belt lock, and / or at the anchorage of the seat belt. Either a tensioned spring (spring force) or a small explosive charge (gas pressure) is used as the energy supply.

[0004] In normal use, when the seat belt is already firmly fixed, the current seat belt tensioner exerts a force of approximately 2 kN on the shoulder. This only causes injury in special cases during normal use. In order that the force does not increase excessively during the forward displacement phase of the occupant after the seat belt has been tensioned, so-called seat belt force limiters have been developed.

[0005] When the airbag control unit obtains information about a collision by means of sensors, the airbag control unit triggers the seat belt tensioner. The trigger threshold can be lower than the trigger threshold of the airbag in some cases (for example, at low speeds). As a result, it may happen that although the seat belt tensioner is triggered, the airbag is not triggered. In modern motor vehicles, the sensors additionally check whether someone is sitting on the seat and has fastened the seat belt. If this is not the case, no triggering occurs.

[0006] There are various designs of seat belt tensioners.

[0007] Relatively common are rotary tensioners (Figs. 1a to 1c). The control unit triggers a pyrotechnic deflagration charge in the seat belt retractor, and the gas pressure of this pyrotechnic deflagration charge accelerates steel balls in the retractor. These steel balls transfer their kinetic energy to a gear on the seat belt retractor shaft. The rotation of the gear further winds up the seat belt, which then presses tightly against the passenger. In the seat belt lock design, the gas pressure of the deflagration charge is transferred to a piston under the seat, and the piston immediately pulls the seat belt lock backward and downward by means of a wire rope and thus tensions the seat belt.

[0008] Another mode of operation is, for example, (Figs. 2 to Figure 5):Rope tensioners, pipe tensioners, and Wankel tensioners (circular piston motors, similar to Wankel motors). Instead of pyrotechnic deflagration packings, a tensioned spring can also exert the required force.

[0009] A modern but relatively expensive design is the reversible seat belt tensioner. In addition to the pyrotechnic seat belt tensioner, an electric drive is used, which can tension the seat belt with a relatively small force (e.g., 100 - 200 N). The reversible seat belt tensioner can be used during dangerous situations in practice without causing an accident due to its diverse usability.

[0010] Among the seat belt tensioners known in the prior art, the force transmission element is formed to act on an actuating element made of metal balls. The disadvantage of these seat belt tensioners is that when using the corresponding motor vehicle (especially when the motor vehicle is equipped with an electric motor), disturbing noise (so-called rattling noise) is caused due to the metal balls hitting each other.

[0011] In addition, the metal balls have a relatively large self-weight. Such metal balls are also relatively costly to manufacture.

[0012] In addition, the metal balls as force transmission elements are usually complex on the same step as the corresponding actuating elements. That is, the individual metal balls must be adjusted to be consistent with the actuating areas of the corresponding actuating elements and must be synchronized with these actuating areas.

[0013] For example, the force transmission elements are disclosed in US 8042835 B2, DE 10 2006 031 359, and DE 10 2006 031 360.

[0014] A seat belt tensioner for a seat belt system is known from JP H08-192 722A. The seat belt tensioner includes a pyrotechnic drive as a drive unit and a force transmission element. After being actuated by the drive unit, the force transmission element engages with a rotatably supported drive wheel, which is coupled to the shaft of the seat belt retractor. In addition, the seat belt tensioner can include a curved guide for the force transmission element, which is at least partially formed as a pressure space.

[0015] A seat belt tensioner is shown in US 44 44 010 A. The seat belt tensioner includes a plurality of force transmission elements, such as spheres. The drive of the power transmission element to the drive wheel is achieved by frictional engagement.

[0016] Furthermore, a sphere tensioner is disclosed in DE 102 31 268 A1. In this sphere tensioner, a channel (through which a pressure transmission element is conveyed to a drive wheel in the form of a sphere) is formed such that at least one of these spheres serves as a piston that seals against the channel wall. Summary of the Invention

[0017] It is an object of the present invention to provide a force transmission element for a device for tensioning a seat belt and a device for tensioning a seat belt having such a force transmission element, which force transmission element and the device for tensioning a seat belt provide an alternative to the force transmission elements known from the prior art.

[0018] Another object of the present invention is to provide a force transmission element that operates safely and reliably.

[0019] There should also be provided a force transmission element that is lighter and can be manufactured economically compared to the force transmission elements known from the prior art.

[0020] One or more of these objects are achieved by the device described below. Advantageous configurations are given in the following description.

[0021] According to the present invention, there is provided a force transmission element for a device for tensioning a seat belt, wherein the force transmission element is a rod-shaped body that substantially has a structure over its entire length and / or is formed at least by a first component and a second component.

[0022] The inventors of the present invention have recognized that: during the injection molding process of manufacturing a force transmission element (which is configured as a rod-shaped body and preferably has a constant cross-section), due to the cooling process of the slender rod-shaped body with a constant cross-section, bubbles, hollow spaces, voids or gas inclusions may especially occur on the outer wall of the rod-shaped body.

[0023] This is because the injection cross-section has solidified before the melt core (plastic core) solidifies. Due to the volume adjustment related to shrinkage caused by cooling the melt, in such a slender member, it can no longer be affected by the melt pressure. The lack of pressure leads to free shrinkage and thus to the formation of cavities and / or voids in the core of the member. It is also technically impossible to provide multiple injection points during the manufacturing process.

[0024] Furthermore, during injection molding, it should be ensured that a wider cross-section is provided on the rod-shaped body at the start of the extrusion process, while the rod-shaped body should have a smaller cross-section at the end of the extrusion process.

[0025] Since the force transmission element can be formed by a first component and a second component, the total length of the rod-shaped body is reduced, so that the rod-shaped body can be made by means of an extrusion process.

[0026] Since the rod-shaped body can have a structure in the axial direction over substantially its entire length, the rod-shaped body can also be manufactured by an injection molding process.

[0027] Here, corresponding undercut dies ( Figure 8 ) are provided, and these undercut dies form structural portions that extend substantially over the entire length of the rod-shaped body. The structural portion or the structure is provided or formed in the form of corresponding grooves, ridges, gaps, depressions, or ribs, which extend substantially over the entire length in the axial direction of the rod-shaped body.

[0028] Within the scope of the present invention, the substantially entire length of the rod-shaped body in the axial direction can be understood as at least 50%, or 60%, or 70%, or 80%, or 90%, or approximately 100% of the total length of the rod-shaped body in the axial direction.

[0029] These structures or corresponding depressions and / or ridges are preferably formed to be rotationally symmetric along and within the outer wall of the rod-shaped body.

[0030] Since the force transmission element is formed of plastic, the member can be relatively light and can be manufactured cost-effectively in addition.

[0031] These two components can be formed of the same plastic or at least two different plastics.

[0032] Suitable plastics for this are, for example, polymers or polyoxymethylene (POM), polyamides (PA) with or without glass fibers, elastomers, etc.

[0033] The at least two components forming the rod-shaped body can each have a connection surface, wherein the connection surface extends transversely to the axial direction or is inclined at a predetermined angle with respect to the longitudinal direction of the rod-shaped body, and wherein these connection surfaces each have correspondingly formed connecting members for connecting the first component and the second component, these connecting members being formed as connecting depressions and / or connecting elements, and wherein preferably a region in the form of an undercut is formed in the connection region between these connecting elements and these connecting depressions.

[0034] When connecting these two components by extrusion (or injection molding), the following situation may occur: that is, a material-locked connection cannot be formed between these two components in the connection region or in the region of the connection surface. Since corresponding connecting depressions and connecting elements are provided and they preferably have corresponding undercuts, the two components forming the rod-shaped body can be connected to each other in a friction-locked manner.

[0035] Therefore, the rod-shaped body can be made by an extrusion process or an injection molding process.

[0036] The rod-shaped body can transmit a force via one of its end faces to an actuating element of a device for tensioning a safety belt, and one of the end faces of the rod-shaped body then forms a force transmission surface and correspondingly has a predetermined rigidity in the longitudinal direction.

[0037] Additionally and / or alternatively, the rod-shaped body can transmit a force via its outer wall to an actuating element of a device for tensioning a safety belt, wherein the outer wall is formed such that it is elastically deformable or plastically deformable at least in a force transmission region that forms the force transmission surface and / or has corresponding actuating depressions that extend substantially transversely to the longitudinal direction of the rod-shaped body.

[0038] By means of the above, it becomes possible to safely and reliably transmit a force from the transmission element to the actuating element of a device for tensioning a safety belt.

[0039] The force transmission region can be a radial section of the rod-shaped body, wherein the region can be deformed up to approximately 90%, or 80%, or 70%, or 60%, or 50%, or 40%, or 30%, or 20%, down to 10% of the diameter of the rod-shaped body. The above percentage specifications also describe the penetration depth of the actuating element into the cross-section of the rod-shaped body.

[0040] Furthermore, a device for tensioning a safety belt is provided with the force transmission element pointed out above. The device for tensioning a safety belt includes a seat belt retractor, which can be displaced in a rotational movement by means of the actuating element such that the safety belt is wound up and / or tensioned, wherein the actuating element is actuated by means of the force transmission element.

[0041] Alternatively, as a replacement for the seat belt retractor, a displacement member, in particular a linear displacement member of a seat belt lock, can also be provided in the device for tensioning a safety belt. The displacement member can then also be realized by means of the force transmission element according to the invention.

[0042] The actuating element of the seat belt retractor can be a rotatably supported drive wheel or a part of a toothed wheel (gear), which is connected or can be connected to the shaft of the seat belt retractor, and wherein the force transmission element contacts the actuating element in the force transmission region such that the seat belt retractor can be displaced in a rotational movement, so that the safety belt can be wound up and tensioned.

[0043] Furthermore, according to the invention, a method for manufacturing the force transmission element 1 pointed out above is also proposed.

[0044] Preferably, the force transmission element 1 is made of a plastic material by means of an injection molding process.

[0045] Alternatively, the force transmission element can also be made of two or more different plastics by means of a two-component or multi-component injection molding process.

[0046] Furthermore, it is also conceivable according to the invention to manufacture the force transmission element by means of an extrusion process.

[0047] The force transmission element can also be manufactured by a co-extrusion process. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The present invention will be described below with reference to the embodiments shown in the drawings. In the drawings:

[0049] Figures 1a to 1c show schematic illustrations of seat belt tensioners known from the prior art,

[0050] Figures 2a and 2b show further schematic illustrations of seat belt tensioners known from the prior art,

[0051] Figures 3a to 3c show further schematic illustrations of seat belt tensioners known from the prior art,

[0052] Figure 4 A perspective view of a further seat belt tensioner known from the prior art is shown,

[0053] Figure 5 A side sectional view of a further seat belt tensioner known from the prior art is shown,

[0054] Figure 6 A perspective view of a first embodiment of a rod-shaped force transmission element for a seat belt tensioner according to the invention is shown,

[0055] Figure 7 Shows Figure 6 a side view of the force transmission element,

[0056] Figure 8 A front view of a rod-shaped force transmission element with two schematically shown undercuts is shown,

[0057] Figure 9 A schematic, side sectional view of another embodiment of the rod-shaped force transmission element is shown, and

[0058] Figure 10 Another side sectional view of an embodiment of the rod-shaped force transmission element is shown. DETAILED DESCRIPTION

[0059] The force transmission element 1 of the device 2 for tensioning a seat belt according to the invention is generally formed cylindrically and extends in the axial direction 3.

[0060] The force transmission element 1 includes two end walls and an outer wall connecting the two end walls ( Figures 6 to 10 ).

[0061] One of the two end walls 4, 5 can be loaded by the gas pressure and / or spring force of the seat belt tensioner 2. The end wall 4 is preferably formed as a continuous, disc-shaped surface that does not have any recesses and forms a force-loading wall.

[0062] According to the first embodiment, the entire outer wall 6 is provided with continuous axial ribs 7 (connecting plates) extending in the axial direction or longitudinal direction 3 of the rod-shaped force transmission element 1.

[0063] The axial ribs 7 are preferably arranged at an angle of 90° or a right angle to each other.

[0064] The axial ribs 7 extending in the longitudinal direction can also be discontinuous and thus have grooves (not shown).

[0065] In addition, transverse ribs 8 (ridges) are provided that extend transversely or orthogonally to the axial direction 3, and these transverse ribs 8 connect the axial ribs 7 extending in the axial direction 3 to each other. Preferably, the transverse ribs 8 are arranged equidistant from each other in the longitudinal direction.

[0066] According to this exemplary embodiment, four main axial ribs 9 are arranged in a cross shape in the cross section, and for each main axial rib 9, a corresponding secondary axial rib 9 is arranged at a right angle to it.

[0067] In the rod-shaped force transmission element 1 or rod body according to this embodiment, the corresponding ribs 7, 8, 9, 10 (ridges) extending in the axial direction 3 and transversely to the axial direction 3 are formed by corresponding undercut dies in the injection molding process ( Figure 8 ).

[0068] The end wall 5 that cannot be loaded by the gas pressure and / or spring force can also have recesses 11 formed corresponding to the axial ribs 7 based on the manufacturing process. The recesses 11 are also arranged at a right angle to each other.

[0069] Depending on whether the force is transmitted by the end wall 5 or the outer wall 6, either the end wall 5 or the outer wall 6 forms a force transmission wall 11.

[0070] This rod body transfers its translational motion to a rotatably supported drive wheel of the seat belt retractor or the device 2 for retracting the seat belt or to the gear of the seat belt retractor, so that the translational motion is converted into a rotational motion.

[0071] Preferably, this can be achieved by elastically deforming the force-transmitting wall 12 of the rod-shaped body and the force-transmitting element 1 that is formed as the outer wall 6, but it can also be achieved by plastically deforming them, respectively.

[0072] Additionally and / or alternatively, corresponding depressions that extend in the radial direction and are formed substantially corresponding to the corresponding teeth of the gear-shaped wheel can be provided, in particular actuation depressions (not shown). These actuation depressions are formed at least partially or completely radially circumferentially in the outer wall 6, extend orthogonally to the axial direction 3, and are arranged equidistantly from each other to actuate the corresponding gears.

[0073] According to an alternative embodiment, the rod-shaped body or the force-transmitting element 1 is formed as a two-piece ( Figure 9 and Figure 10 ).

[0074] Here, it can be proposed that the first part and the second part 13, 14 of the rod-shaped body 1 are made of the same plastic or two different plastics.

[0075] The first part and the second part 13, 14 each have a first connection surface and a second connection surface 15, 16 on the end-side section.

[0076] According to the exemplary embodiment, the connection surface 15 extends transversely or orthogonally to the axial direction 3 of the rod-shaped body 1 ( Figure 9 ). A substantially mushroom-shaped connection element 17 is integrally formed in the region of the connection surface of the first rod-shaped body.

[0077] The second part 14 of the rod-shaped body 1 has a connection depression 18 formed corresponding to the connection element 17 of the first part 13 of the rod-shaped body 1.

[0078] Preferably, the first part and the second part 13, 14 are manufactured together with the connection element 17 and the connection depression 18 in a single injection molding process.

[0079] These two parts can be made of the same plastic. Alternatively, such a force-transmitting element can also be made of two different plastics in a two-component injection molding process.

[0080] Alternatively, the first part of the rod-shaped body 1 can also be manufactured first by an extrusion process and then the second part of the rod-shaped body.

[0081] Another embodiment of the rod-shaped body formed by the first part and the second part is shown in Figure 10 .

[0082] The connecting surfaces 15, 16 of the first part and the second parts 13, 14 are inclined oppositely with respect to the axial direction and the longitudinal direction 3 of the force transmission element 1 (rod-shaped body). Preferably, the first part and the second parts 13, 14 of the rod-shaped body 1 have a plurality of connecting elements 17 and a plurality of connecting recesses 18 formed corresponding to each other.

[0083] The rod-shaped body 1 according to this embodiment can also be made by an extrusion process and an injection molding process, wherein first the first part or the second parts 13, 14 are formed and then the second part or the first part is formed correspondingly.

[0084] Furthermore, according to the present invention, there is provided a device 2 for tensioning a safety belt, which device for tensioning a safety belt includes a force transmission element according to the present invention. Therefore, the force transmission element 1 is also applicable to the device 2 for tensioning a safety belt known from the prior art and partially shown in the figures (Figures 1 to 3).

[0085] Known safety belt tensioners 2 usually have a force transmission element, such as a plurality of spheres arranged in sequence, which are first stored in a pipe and are subjected to a high-pressure action when the gas generator is activated (Figures 1a to 1c).

[0086] Thereby, these spheres are pushed forward from the pipe and drive a drive wheel coupled to the safety belt reel.

[0087] Other force transmission elements used in known safety belt tensioners are racks, chains, molded bodies or also the compressed gas itself generated by a gas generator (drawings).

[0088] Such a force transmission element can be replaced by a force transmission element 1 formed correspondingly according to the present invention.

[0089] The force transmission element 1 can be formed of an elastically deformable or plastically deformable material, wherein the material is preferably formed elastically such that the material adapts to the course of the curved guide portion of the device 2 for tensioning a safety belt, and wherein once the drive unit is actuated, the drive wheel penetrates into the material of the force transmission element ( Figure 4 and Figure 5 ).

[0090] The deformable material can be understood as, for example, a material that visibly deforms once it comes into contact with the drive wheel. Examples thereof are: EPDM materials, rubbers, natural rubbers or (soft) thermoplastics with different Shore hardnesses (70 to 95 Shore).

[0091] According to the present invention, there is also provided a method for manufacturing the force transmission element 1 described above.

[0092] Preferably, the force transmission element 1 is made of a plastic material by an injection molding process.

[0093] Alternatively, the force transmission element can also be made of two or more different plastics by a two-component or multi-component injection molding process.

[0094] Here, the plastic is liquefied (plasticized) by means of an injection molding machine and injected into a mold (i.e., an injection molding tool) under pressure. In the tool, the substance returns to the solid state through a cooling or crosslinking reaction and is removed as a finished product after the tool is opened. The cavities of the tool determine the shape and surface structure of the finished product.

[0095] Furthermore, an undercut mold 19 is provided to form corresponding structures or ribs in the outer wall 6.

[0096] Furthermore, it is also conceivable according to the invention to manufacture the force transmission element by an extrusion process.

[0097] During extrusion, a viscous, curable plastic mold mixture is continuously pressed out under pressure from a shaping opening (also referred to as a nozzle, die opening, or spout). Thereby, a force transmission element having a structure corresponding to the cross-section of the opening is produced.

[0098] The force transmission element can also be manufactured by co-extrusion.

[0099] List of reference numerals

[0100] 1 Force transmission element

[0101] 2 Device for tensioning the safety belt

[0102] 3 Axial direction

[0103] 4 End wall

[0104] 5 End wall

[0105] 6 Outer wall

[0106] 7 Axial rib

[0107] 8 Transverse rib

[0108] 9 Main axial rib

[0109] 10 Secondary axial rib

[0110] 11 Depression

[0111] 12 Force transmission wall

[0112] 13 First component

[0113] 14 Second component

[0114] 15 Connection surface

[0115] 16 Connecting surface

[0116] 17 Connecting element

[0117] 18 Connecting recess

[0118] 19 Undercut die

Claims

1. A force transmission element for a device for tensioning a belt, wherein the force transmission element: is a rod-shaped body formed of plastic, the rod-shaped body having a structure over its entire length, wherein the rod-shaped body includes axial ribs extending in the axial direction of the rod-shaped body and transverse ribs extending transverse to the axial direction and interconnected with the axial ribs; and is formed of at least a first part and a second part, wherein both the first part and the second part include connecting surfaces that extend transverse to the axial direction or are inclined at a predetermined angle with respect to the axial direction, and wherein the connecting surfaces of the first part and the connecting surfaces of the second part have matingly engaging connecting portions, the connecting portions including at least one connecting element and at least one connecting recess, the connecting element engaging in the connecting recess, wherein the connecting element and the connecting recess are configured such that the undercut of the connecting recess holds the connecting element in the connecting recess.

2. The force transmission element (1) according to claim 1, characterized in that the axial ribs are arranged rotationally symmetrically and are formed in the outer wall (6) of the rod-shaped body.

3. The force transmission element (1) according to claim 1, characterized in that the two parts are formed of the same plastic or of at least two different plastics.

4. The force transmission element (1) according to claim 1, characterized in that the rod-shaped body is made of plastic by an extrusion process or an injection molding process.

5. The force transmission element (1) according to claim 1, characterized in that the rod-shaped body includes end faces that form force transmission faces and have a predetermined rigidity in the axial direction, or the rod-shaped body includes an outer wall (6), and the outer wall (6) has a force transmission face at least in one force transmission region, the force transmission face being elastically deformable or plastically deformable and / or having corresponding actuation recesses that extend generally transverse to the axial direction of the rod-shaped body.

6. A device (2) for tensioning a safety belt, the device for tensioning a safety belt having a force transmission element according to any one of claims 1 to 5, the device for tensioning a safety belt including a seat belt retractor that can be displaced in a rotational movement by means of an actuating element such that the safety belt is wound up or tensioned, wherein the actuating element can be actuated by the force transmission element (1).

7. The device according to claim 6, characterized in that the force transmission element (1) has a continuous end wall (4) that can be loaded with force by gas pressure and / or spring force, wherein the other end wall (4) is formed or configured to be continuous.

8. The device according to claim 6, characterized in that The actuating element of the seat belt retractor is part of a rotatably supported drive wheel or a toothed wheel, which is connected or connectable to the shaft of the seat belt retractor, and wherein the force transmission element (1) contacts the actuating element in the force transmission area such that the seat belt retractor can be displaced in a rotational movement, so that the seat belt can be wound up and tensioned.

9. A method for manufacturing a force transmission element (1) according to one of claims 1 to 5, wherein the force transmission element (1) is made by a single-component or multi-component injection molding process or by an extrusion process.

10. A force transmission element for a device for tensioning a belt, wherein the force transmission element is formed at least by a first part and a second part, wherein both the first part and the second part include a connecting surface, which extends transversely to the axial direction of the force transmission element or is inclined at a predetermined angle with respect to the axial direction, and wherein the connecting surface of the first part and the connecting surface of the second part have mating connecting portions, the connecting portions including at least one connecting element protrusion and at least one connecting recess, the connecting element protrusion engaging in the connecting recess, wherein the connecting element protrusion and the connecting recess are configured such that the undercut of the connecting recess holds the connecting element protrusion in the connecting recess.

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