Device for simulating seat belt relaxation and / or for simulating seat belt force

Abstract

The invention relates to a device for simulating a seat belt slack and / or for simulating a seat belt force, comprising: a guide (12) for a seat belt (20), comprising a plurality of stationary guide elements (14) and a movable deflection element (16), the steering element can be adjusted from an initial state to an end state via an intermediate state relative to the stationary guide element; and at least one inertial mass (18); a guide path (17) for the safety belt (20), which is defined by the deflection element (16) and the adjacent guide element (14), is V-shaped in an initial state and the deflection element (16) and the inertial mass (18) do not interact, and wherein the guide path appears in a weaker V-shape in an intermediate state and the deflection element (16) and the inertial mass (18) interact, the specified guide path (17) is at least approximately linear in the end state.

Description

Technical Field

[0001] The invention relates to a device for simulating seat belt slack and / or for simulating seat belt force. Background Art

[0002] Seat belt systems for vehicles usually have, in addition to the seat belt itself, a safety device in the form of one or more belt tensioners.

[0003] The seat belt tensioner provides a restraining effect for the vehicle occupant in a triggering scenario or shortly before a potential triggering scenario by tensioning the seat belt against the vehicle occupant by the seat belt tensioner before or immediately after the vehicle occupant moves forward and possibly other occupant restraints are triggered. Belt slack (i.e. slack in the webbing against the vehicle occupant) and the film effect (i.e. slack in the webbing wound on the reel) can also be eliminated by tensioning the seat belt, so that the vehicle occupant can participate in vehicle deceleration in advance. In this context, a distinction is made between different types of seat belt tensioners.

[0004] On the one hand, comfort tensioners are known, which can rotate the belt drum in the tensioning direction and can reversibly tension the belt. Comfort tensioners typically include an electric motor, a gear and a coupling pawl. The coupling pawl can engage in a drive wheel coupled to the belt drum.

[0005] Thus, the rotational movement of the electric motor can be applied to the belt drum via the gears when the coupling claws are engaged and cause the belt drum to rotate in the tensioning direction. An important feature of the comfort tensioner is that the belt drum can be released again or rotated in the unwinding direction, for example when the situation that triggered the comfort tensioning, such as full braking, no longer exists.

[0006] On the other hand, high-efficiency tensioners are known. They tension the seat belt in a triggering scenario and are typically driven pyrotechnically. Here, by igniting the gunpowder in the gas generator, sufficient energy is provided in a very short time for tensioning the seat belt to rotate the belt reel in the tensioning direction.

[0007] It applies here that both the comfort tensioner and the high-performance tensioner were tested and verified empirically during the development process. Based on the empirically ascertained knowledge, the seat belt system was further developed.

[0008] This is achieved according to the prior art by means of a test set-up comprising a vehicle seat, a dummy and a seat belt system, as if it were installed in a vehicle. In the test, a restraint situation is simulated, so that the seat belt tensioner is triggered and the family member is secured in the vehicle seat.

[0009] The disadvantage here is that such a construction is extremely time-consuming and expensive. In addition, such a test construction requires a lot of space.

[0010] Furthermore, recording measured values ​​when the belt tensioner is triggered in order to determine the belt behavior is complicated. This is especially true because a plurality of sensors need to be arranged distributed over the test set-up in order to record the measured values. Furthermore, reproducibility may only be possible to a limited extent with such a test set-up, which can also negatively affect the comparability of individual tests with one another. Summary of the invention

[0011] The object of the present invention is to provide a device which can replace the previously complex experimental arrangements, can be operated more efficiently, requires less space and provides more reproducible results.

[0012] The proposed object is achieved according to the invention by a device for simulating seat belt slack and / or for simulating seat belt force, the device comprising: a guide for the seat belt, the guide comprising a plurality of stationary guide elements and a movable steering element, the steering element being adjacent to two stationary guide elements and being adjustable from an initial state to an end state via an intermediate state relative to the two stationary guide elements; and at least one inertial mass, a guide trajectory for the seat belt defined by the steering element and the adjacent guide element being V-shaped in an initial state and the steering element and the inertial mass not acting together, the guide trajectory appearing as a weaker V-shape in an intermediate state and the steering element and the inertial mass acting together, so that the mass inertia of the inertial mass resists the movement of the steering element toward the end state and the defined guide trajectory of the webbing is at least approximately a straight line in the end state.

[0013] The basic idea of ​​the invention is to replace the complex test configuration with the dummy mentioned above with a kinematically simpler alternative system, which however simulates all physical influencing variables present during the restraint process, such as those due to the seat belt course and the vehicle occupant or dummy.

[0014] The frictional resistance due to the contact of the dummy and the winding of the belt is simulated in the device by the course of the belt along the guide, the surface properties of the guide elements and the surface properties of the deflection elements, and the wrapping angle of the belt around the guide elements and the deflection elements.

[0015] At high belt accelerations, in particular belt accelerations exceeding 5000 g, the dynamic resistance of the belt is dependent on the nonlinear belt flexibility and belt inertia. This is also taken into account in the device by the guide along which the belt is guided and by using a belt whose length corresponds to the length in the classic test configuration.

[0016] The flexibility of the shoulders, chest and pelvis as well as the belt slack, which is caused, for example, by clothing or a belt buckle that is not resting on the vehicle seat or the vehicle occupant, is simulated by the movable deflection element, by its inherent inertia and also by interaction with inertial masses. Furthermore, the guide allows a tensile wave to propagate within the belt during the tensioning process of the belt, which has a time- and inertia-dependent effect on the reduction of the belt slack, as can also be the case in a classic test configuration.

[0017] In the initial state, the predetermined guide trajectory for the seat belt is V-shaped, which thus represents a state in which the seat belt has a certain seat belt slack and extends along the vehicle occupant or dummy, so that the seat belt only rests on the surface and the body is still not compliant in the area of ​​the shoulders, chest and pelvis.

[0018] In the intermediate state, the V-shape of the guide track is already more weakly apparent, and the intermediate state therefore represents a state in which the belt slack has begun to be reduced and the belt acts on the body first slightly and then increasingly more strongly, so that the body complies at the locations mentioned above, wherein the effective length of the belt is reduced.

[0019] The inertial mass cooperating with the deflection element and opposing its movement toward the end state is the inertial resistance of all masses in the system accelerated by the webbing, which builds up as the flexibility and belt slack in the system decrease.

[0020] The approximately straight-line guide path in the end state is symbolic for the seat belt which secures the vehicle occupant or dummy in the seat and is now under tension. In this state, there is no longer any seat belt slack.

[0021] The adjustment of the deflection element from the initial state via the intermediate state to the end state is achieved by activating the belt tensioner, which reduces the effective length of the belt running along the guide so that the deflection element is forced to move away from the initial state.

[0022] Here, the comfort tensioner is first activated, which reduces the belt slack within the guide and the deflection element may already be slowly moved away from the starting position. The belt slack can also be reduced by simulating a forward movement of the occupant. For this purpose, for example, an additional actuator can act on the webbing.

[0023] The high-efficiency tensioner is then activated, resulting in a sudden increase in the force acting in the seat belt, causing the steering element to suddenly accelerate strongly. While the steering element is performing this acceleration movement in the intermediate state, the steering element encounters an inertial mass, which resists the acceleration movement through its mass inertia and thus reduces the acceleration of the steering element.

[0024] Such a device can be realized in an extremely space-saving manner. In addition, with this device, reproducible results can be achieved based on always the same environmental conditions.

[0025] Furthermore, by modifying the static guide element, very different belt courses can be easily realized.

[0026] Furthermore, by adapting the deflection element and its deflection, very different scenarios with different body flexibility and belt slack in the system can also be simulated.

[0027] In addition, such a configuration facilitates recording of measurement data.

[0028] According to one aspect of the invention, the deflection element can be pivotable about a first axis, thereby allowing the movable deflection element to be adjustable relative to an adjacent guide element and thus to be movable from an initial position via an intermediate position toward an end position.

[0029] The deflection element may have a web, one end of which is supported in the region of the first axis. The pivoting movement of the deflection element may be adjusted via the length of the web.

[0030] The inertial mass can be pivotable about the second axis. This allows, once the inertial mass interacts with the steering element in the intermediate state, the inertial mass to counteract the movement of the steering element toward the end state solely by its inherent mass inertia and yet simultaneously allow the movement of the steering element.

[0031] Preferably, a plurality of individual inertial masses can be provided, the mass inertia of which can successively and stepwise counteract the movement towards the end state in the intermediate state of the steering element.

[0032] Therefore, the increase of the mass inertia resisting the steering element can be achieved by the movement towards the end state. This means that the mass inertia resisting the steering element is initially small and increases successively, because as the movement increases, more and more inertial mass resists the movement of the steering element towards the end position.

[0033] This results in the steering element being braked again by the inertial mass, the steering element being moved from the initial state via the seat belt tensioned by the seat belt tensioner to the intermediate state and performing an acceleration movement due to the activation of the high-efficiency tensioner. Similarly or additionally, this can also be achieved by activating an actuator which simulates the forward movement of the occupant.

[0034] Advantageously, a lock for the inertial mass can be provided. If the deflection element has reached an end state and is no longer in contact with the inertial mass, such a lock ensures that the inertial mass is fixed and does not, for example, encounter a seat belt next to the deflection element.

[0035] Advantageously, a first positioning bracket can be provided for the steering element, on which the steering element rests in the initial state, and / or a second positioning bracket can be provided for the inertial mass, on which the inertial mass rests when the steering element is in the initial state and at least partially when the steering element is in an intermediate state.

[0036] Therefore, the first positioning bracket allows the steering element to be kept in a defined initial state. It is also conceivable here that the positioning bracket can be adjusted according to different situations of demand so that the initial state of the steering element can also be specifically adapted.

[0037] The second positioning bracket for the inertial mass or the plurality of inertial masses serves to position the inertial mass in a defined manner so that the inertial mass encounters the one or more inertial masses in an intermediate state at a desired time during the movement of the steering element. It is also conceivable that the second positioning bracket can be specifically adjusted in order to adjust the one or more inertial masses.

[0038] The deflection element may be assigned a first spring element and / or the inertial mass may be assigned a second spring element.

[0039] The two spring elements can each be either a tension spring or a compression spring.

[0040] The first spring element assigned to the deflection element preferably acts in this case such that the deflection element is fixed on the first positioning bracket as long as no force acts via the seat belt. Therefore, the spring force acts towards the positioning bracket.

[0041] The same applies to the second spring element, which is intended to hold the inertial mass on the second positioning carrier until the deflection element interacts with the inertial mass or masses.

[0042] Furthermore, it is also possible for the first spring element to act on a web of the deflection element.

[0043] Here, it is applicable to the two spring elements that they counteract the movement direction of the steering element from the initial state to the end state with a spring force. This is achieved indirectly via the one or more inertial masses by the second spring element.

[0044] Preferably, the first spring element can act on the deflection element in the direction of the first positioning bracket and / or the second spring element can act on the inertial mass in the direction of the second positioning bracket.

[0045] Furthermore, a comfort tensioner and / or a high-performance tensioner can be provided, which are each mounted on a bracket. The bracket allows the comfort tensioner and the high-performance tensioner to be adapted and quickly replaced according to different situations of the test configuration. The brackets are positioned in such a way that they are each arranged in the region of the guide in which the ends of the seat belt are respectively located. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The present invention is explained below with the aid of the embodiments described in the accompanying drawings. The accompanying drawings are as follows:

[0047] Figure 1 A schematic diagram of a device according to the invention with a guide;

[0048] Figure 2 A section of a guide of the device according to the invention is shown, comprising a deflection element and a plurality of inertial masses in an initial state;

[0049] Figure 3 A section of a guide of the device according to the invention is shown, including a deflection element and an inertial mass according to a second embodiment;

[0050] Figure 4 displaying a graph illustrating the tension and movement of the seat belt over time as the seat belt is tensioned;

[0051] Figure 5 show Figure 2 a section including a steering element in an intermediate state;

[0052] Figure 6 show Figure 2 a section including a steering element in an intermediate state;

[0053] Figure 7 show Figure 2a section including the steering element in an intermediate state and shortly before contact with one of the inertial masses;

[0054] Figure 8 show Figure 2 a section including a steering element in an intermediate state and in contact with one of the inertial masses;

[0055] Fig. 9 show Figure 2 a section including a steering element in an intermediate state and in contact with all inertial masses; and

[0056] Fig.10 show Figure 2 section, including a steering element in the terminal state. DETAILED DESCRIPTION

[0057] Figure 1 A device 10 for simulating seat belt slack and for simulating seat belt forces is shown, the device having a guide 12 for the webbing.

[0058] The guide 12 comprises a plurality of stationary guide elements 14 and a movable deflection element 16 which is adjacent to two stationary guide elements 14 and which can be adjusted relative thereto from an initial state via an intermediate state to an end state. The different states will be explained below.

[0059] The stationary guide element 14 and the movable deflection element 16 define a guide path 17 along which the seat belt 20 can extend.

[0060] Furthermore, in order to determine the forces present along the guide path 17 and therefore on the seat belt 20 , a displacement sensor 21 is provided for determining the movement of the webbing.

[0061] Furthermore, the device 10 comprises an inertial mass 18 which is associated with the movable deflection element 16 .

[0062] Furthermore, the device 10 has two supports 22, one support 22 being used to mount a reversible comfort tensioner 24 to be tested and the other support 22 being used to mount a high-performance tensioner 26 to be tested. The mounting of the comfort tensioner is here in particular an option, i.e. the device can also be used with only a high-performance tensioner 26 as the only tensioning element.

[0063] The guide path 17 extends in such a way that the ends 28 of the belt webbing 20 introduced into the guide 12 are guided toward the holders 22 so that they can be received by the reversible comfort tensioner 24 or high-performance tensioner 26 to be tested.

[0064] Figure 2 The guide 12 and the section of the guide path 17 are shown schematically, on which the deflection element 16 and the respective inertial masses 18 are arranged in the initial state.

[0065] The movable deflection element 16 is in the initial state. At this time, it defines, together with two adjacent stationary guide elements 14, a V-shaped course of the guide track 17 for the safety belt 20 in the region between the two stationary guide elements 14. In addition, one of the stationary guide elements can be provided with a force measuring device.

[0066] The movable deflection element 16 is pivotable about a first axis A.

[0067] Furthermore, the deflection element has a deflection guide 29 and a web 30 , wherein one end of the web 30 is connected to the deflection guide 29 and the other end of the web is supported in the region of the first axis A.

[0068] The deflection guide 29 moves along the movement path B if a pivoting movement of the deflection element 16 occurs.

[0069] The guide path 17 extends along the outer contour of the deflection guide 29 .

[0070] The steering element 16 in the initial state rests on the first positioning bracket 32 ​​in the area of ​​the connecting plate 30, and a first spring element 34 is installed in the area of ​​the connecting plate 30, which is configured as a tension spring and the opposite end of the first spring element is fixed to the support 36, so that: the spring force caused by the first spring element 34 acts, and therefore the steering element 16 is held in the direction of the positioning bracket.

[0071] Furthermore, an end stop 38 is provided for the deflection element 16 .

[0072] The inertial masses 18 have an L-shape, parts of which project into the V-shaped region of the guide path 17. Alternative designs of the inertial masses 18 are easily possible.

[0073] Furthermore, the inertial masses have contact sections 40 facing the deflection guide 29 of the deflection element 16 , which contact sections extend along the guide path B one after the other.

[0074] Furthermore, the inertial masses are mounted so as to be pivotable about a second axis C at their ends opposite the contact section 40 .

[0075] Furthermore, a second positioning support 42 is provided, against which the inertial masses 18 rest as long as there is no contact between the contact sections 40 and the deflection guide 29 .

[0076] In addition, a second spring element 44 is provided, which is configured as a compression spring and acts with one end on the side of each inertial mass 18 opposite to the second positioning bracket 42, and the other end of the second spring element is supported on a support 46, so that each inertial mass is pressed toward the second positioning bracket 42 by the spring force of the second spring element 44.

[0077] Furthermore, a locking device 48 is arranged on the support 46 , which locking device is associated with each inertial mass 18 .

[0078] Figure 3 Another way to display inertial mass. Figure 2 In contrast to the embodiment shown in , the inertial masses 18 are arranged about a first axis A of the movable deflection element 16 .

[0079] In this exemplary embodiment, the inertial masses have a ring shape, each of which has an open ring segment 50. The dimensions of the open ring segments 50 differ from one another, so that the contact sections 40 are arranged offset from one another.

[0080] The web 30 extends from the first axis A from the open ring segment 50 to the deflection guide 29 . The movement of the deflection guide 29 along the guide path B has the result that the web 30 comes into contact with the contact sections 40 one after the other.

[0081] Below from Figure 2 Starting and additionally with the help of Figures 4 to 10 The functionality of device 10 is explained.

[0082] Figure 4 A graph is shown, comprising a first graph 52 and a second graph 54. The first graph 52 describes the tensile force acting in the seat belt 20 over time. The second graph 54 describes the displacement of the seat belt 20 over time. The dashed lines drawn in the graph describe different times during the operation of the device 10 and are used for comparison in the further explanation.

[0083] When the device 10 is in operation, the tensile force acting in the seat belt 20 or the movement of the belt is detected by the displacement sensor 21 .

[0084] In addition, the amount of movement of the seat belt 20 and optionally the speed of movement of the seat belt 20 are also ascertained by means of the camera system and a scale applied to the seat belt.

[0085] In addition, other various parameters are also measured.

[0086] As already mentioned in the above explanation, Figure 2The deflection element 16 is shown in the initial state. In this case, the deflection element 16 rests on the first positioning bracket 32 ​​and the guide path 17 of the seat belt 20 has a V-shaped course in the region of the deflection element 16 and the guide element 14 adjacent to it. Both the displacement of the seat belt and the tension in the seat belt are identical here (see Figure 4 , position 56).

[0087] In a first step, the comfort tensioner 24 mounted on the bracket 22 starts to remove the belt slack from the system, whereby a portion of the belt 20 moves towards the comfort tensioner 24. Alternatively or additionally, the belt slack is removed by the occupant moving forward. This is simulated by the actuator 25. As a result, the belt 20 is pre-tensioned, so that a tension is built up in the belt 20 (see Figure 4 , position 58).

[0088] This is Figure 5 , the movement of the seat belt 20 is schematically illustrated here by an arrow, and the amount of the movement of the seat belt 20 is illustrated by way of example by the length of the arrow.

[0089] At the same time, the deflection element 16 is pivoted from the initial state to the intermediate state in the counterclockwise direction, so that the deflection guide 29 of the deflection element 16 moves along the guide trajectory B as well.

[0090] In this case, the deflection element 16 is no longer in contact with the first positioning bracket 32 ​​.

[0091] The V-shape of the guide track 17 starts to become flatter. In other words, the angle measured between the two legs of the "V" on the inside becomes larger.

[0092] The tension in the seat belt 20 mentioned above (see Figure 4 , position 58 ) is achieved because the deflection element 16 is loaded by the first spring element 34 with a spring force which acts in the clockwise direction about the axis A and therefore counter to the direction of movement B of the deflection element 16 .

[0093] In the next step, while the reversible comfort tensioner 24 is still tensioning the seat belt 20 , the high-efficiency tensioner 26 is activated.

[0094] This results in a sudden movement of the seat belt 20 in the direction of the high-efficiency tensioner 26 (see Figure 6 , large arrow on the right). Therefore, a strong increase in the tension in the safety belt 20 follows (see Figure 4 , position 60).

[0095] Furthermore, a tensile wave is generated in the seat belt 20 , which can propagate freely along the guide track 17 due to the guide 12 .

[0096] This also leads to a strong acceleration of the deflection element 16 about the first axis A in the counterclockwise direction, so that the deflection guide 29 executes an acceleration movement along the guide path B.

[0097] In this case, the deflection element 16 is still in the intermediate state and continues to move toward the contact section 40 of the inertial masses 18 .

[0098] Shortly before the deflection element 16 or the deflection guide 29 comes into contact with the contact section 40, the seat belt reaches its maximum speed due to the movement (see Figure 4 , position 62). Only the movement of the seat belt 20 towards the high-efficiency tensioner 26 is performed (see Figure 7 , two arrows pointing right).

[0099] Figure 8 The deflection element 16 is shown in an intermediate state after the deflection guide 29 has encountered the contact section 40 of the first inertial mass 18 .

[0100] The V-shape of the guide track 17 becomes even flatter.

[0101] As a result, the acceleration acting on the deflection element 16 is reduced, whereas the inertial mass 18 is accelerated due to the contact with the deflection element 16 .

[0102] The tension in the seat belt 20 reaches its maximum value (see Figure 4 , position 64), and the high-efficiency tensioner 26 is braked due to the resistance existing in the system, so that the speed of the seat belt 20 also begins to decrease.

[0103] As in Fig. 9 As described in , the deflection element 16 continues to move in the counterclockwise direction and at this time successively encounters the contact sections 40 of the second and third inertial masses 18, so that the movement of the deflection element 16 is additionally braked because their mass inertia resists the movement of the deflection element along the movement path B.

[0104] In addition, the spring force of the second spring element 44 also counteracts the movement direction of the deflection element 16 .

[0105] The V-shaped course of the movement path 17 is already significantly less pronounced than in the starting state. In addition, the tension is also reduced, wherein both the tension in the seat belt 20 and the movement of the seat belt 20 slowly approach defined values, so that the tension in the seat belt 20 results in a defined constant restraining force and at least approximately no change in the movement of the seat belt 20 occurs (see Figure 4 , position 66).

[0106] Since the high-efficiency tensioner 26 only causes a slight movement of the seat belt 20, it can be locked shortly before this in order to maintain the tension in the seat belt 20 (see Fig. 9 , small arrow on the right).

[0107] Fig.10 The deflection element 16 is shown in the end position. The movement of the deflection element 16 is limited by an end stop 38 which acts on the link plate 30 .

[0108] The inertial masses 18 are held in position by a lock 48 when the deflection element 16 is in the end position in order to prevent them from coming into contact with the seat belt 20 .

[0109] Since the movable deflection element 16 or its deflection guide 29 is no longer in contact with the seat belt 20 , an approximately straight guide path 17 for the seat belt 20 exists between the stationary guide elements 14 adjacent to the deflection element 16 .

[0110] If the end state is reached, the high-efficiency tensioner 26 is locked. Not only the tension of the seat belt 20 but also the displacement of the seat belt remain at least approximately constant in the end state (see Figure 4 , position 68). The change in the curve course can be produced, for example, by a force limiter, which causes the seat belt 20 to be released.

Claims

1. A device for simulating seat belt slack and / or for simulating seat belt force, the device comprising: A guide (12) for a safety belt (20), the guide comprising a plurality of stationary guide elements (14) and a movable deflection element (16), the deflection element being adjacent to two stationary guide elements (14) and being adjustable relative to the two stationary guide elements from an initial state via an intermediate state to an end state; as well as at least one inertial mass (18); A guide path (17) for a seat belt (20) defined by the deflection element (16) and an adjacent guide element (14) is V-shaped in an initial state and the deflection element (16) and the inertial mass (18) do not interact, the guide path appears to be a weaker V-shape in an intermediate state and the deflection element (16) and the inertial mass (18) interact so that the mass inertia of the inertial mass (18) counteracts the movement of the deflection element (16) toward an end state and the defined guide path (17) is at least approximately a straight line in the end state.

2. The device according to claim 1, characterized in that The steering element (16) is pivotable about a first axis (A).

3. The device according to claim 2, characterized in that The deflection element (16) has a web (30), one end of which is supported in the region of a first axis (A).

4. The device according to any one of the preceding claims, characterized in that The inertial mass (18) is pivotable about a second axis (C).

5. The device according to any one of claims 1 to 3, characterized in that The inertial mass (18) is pivotable about a first axis (A).

6. The device according to any one of the preceding claims, characterized in that A plurality of individual inertial masses (18) are provided, the mass inertia of the individual inertial masses (18) counteracting successively and in stages in intermediate states of the steering element (16) when moving toward an end state.

7. The device according to any one of the preceding claims, characterized in that A lock (48) is provided for the inertial mass (18).

8. The device according to any one of the preceding claims, characterized in that A first positioning bracket (32) is provided for the steering element (18), on which the steering element (16) rests in an initial state, and / or a second positioning bracket (42) is provided for one or more of the inertial masses (18), on which the one or more of the inertial masses (18) rests when the steering element (16) is in the initial state and at least partially when the steering element (16) is in an intermediate state.

9. The device according to any one of the preceding claims, characterized in that The deflection element (16) is associated with a first spring element (34) and / or the inertial mass (18) is associated with a second spring element (44).

10. The device according to claim 9, as long as it is dependent on claim 8, characterized in that The first spring element (34) acts on the deflection element (16) in the direction of the first positioning bracket (32), and / or the second spring element (44) acts on the inertial mass (18) in the direction of the second positioning bracket (42).

11. The device according to any one of the preceding claims, characterized in that A reversible comfort tensioner (24) and / or a high-efficiency tensioner (26) are provided, wherein the comfort tensioner and / or the high-efficiency tensioner are respectively mounted on a bracket (22).

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