Assembly for a seat belt retractor

Abstract

The invention relates to an assembly (11) for a belt retractor (10) of a motor vehicle, comprising a belt reel (14), a belt tightener (16) and a drive gear (24) which engages in a torque-transmitting manner with the belt reel (14) and on which a force transmission element (20) of the belt tightener (16) can act, a drive gear (24) for driving the seatbelt reel (14) in the seatbelt take-up direction, an overload clutch (28) being provided between the drive gear (24) and the seatbelt reel (14), and the force transmission element (20) remaining in continuous engagement with the drive gear (24) after the seatbelt tightener (16) is triggered.

Description

Technical Field

[0001] This invention relates to a component for a motor vehicle seatbelt retractor. Background Technology

[0002] Seatbelt retractors typically include a seatbelt tensioner that is triggered when needed to eliminate seatbelt slack and pre-tension the seatbelt. This means that the seatbelt retractor is driven by a seatbelt reel in the direction of seatbelt retraction. This seatbelt reel is rotatably supported in a frame.

[0003] Such seatbelt retractors are well known in the prior art. They are used to provide seatbelts for motor vehicle occupants. In normal operation, vehicle occupants can freely pull the seatbelt from the seatbelt reel against the action of the winding spring, and when vehicle occupants, for example, unfasten the seatbelt, the seatbelt reel rewinds the seatbelt.

[0004] When the seatbelt reel is locked in the frame, the seatbelt cannot be pulled further from the seatbelt reel before a predetermined load limit is reached.

[0005] Once activated, the seatbelt pretensioner drives the seatbelt reel either directly or indirectly via a force limiter (typically a torsion bar). The force limiter is located inside the seatbelt reel and is torsionally connected to the reel at one axial end and to the frame at the other end. When the load limit is exceeded, the torsion bar twists and deforms. This reduces the force peak in the seatbelt, which would otherwise place a significant burden on the vehicle occupants. In other words, the force limiter allows the seatbelt reel to rotate relative to the frame under the tension of the seatbelt.

[0006] Ideally, when the seatbelt pretensioner is triggered, the seatbelt is pre-tensioned with a force close to the load limit level of the force limiter, i.e., at a level from which the force limiter allows the seatbelt reel to rotate in the unwinding direction.

[0007] If the seatbelt pretensioner directly drives the seatbelt reel, this load limit may be exceeded. This is especially true if there is only a small amount of seatbelt slack when the pretensioner is activated. In this case, the force in the seatbelt increases rapidly. For example, this could be due to full braking before pretensioner activation, or because the seatbelt slack may have decreased significantly due to a delay in ignition timing during a collision. Furthermore, the force transmission mechanism of the seatbelt pretensioner may jam, resulting in increased resistance when force is subsequently limited by torsion bar deformation.

[0008] To address these issues, it is known to pretension the seatbelt by driving the seatbelt reel in the retraction direction using a torsion bar. However, a drawback of this solution is that the torsion bar may have already undergone plastic deformation during the pretensioning process. Summary of the Invention

[0009] Therefore, the object of the present invention is to provide an improved seat belt retractor.

[0010] According to the invention, this objective is achieved by an assembly for a motor vehicle seatbelt retractor, comprising a seatbelt reel, a seatbelt tensioner, and a drive gear that is torque-transmittingly engaged with the seatbelt reel, and a force-transmitting element of the seatbelt tensioner acting on the drive gear to drive the seatbelt reel in the seatbelt retraction direction. An overload clutch is provided between the drive gear and the seatbelt reel. The force-transmitting element remains continuously engaged with the drive gear after the seatbelt tensioner is triggered.

[0011] Because the force transmission element remains continuously engaged with the drive gear, it provides the possibility of transmitting sufficient torque to trigger the overload clutch under any circumstances. By triggering the overload clutch, the force transmission element and drive gear are disengaged from the seatbelt reel, ensuring that the force transmission element does not affect the resistance of the seatbelt reel during subsequent force limiting. This also prevents the seatbelt from overloading during and after pretensioning.

[0012] Furthermore, due to the uniform load distribution—specifically, its uniform distribution across many blades of the drive gear—excellent load transfer from the force transmission components to the drive gear is achieved. Compared to known solutions, the maximum torque that can be transmitted to the drive gear is significantly increased.

[0013] Because the force transmission component remains continuously engaged with the drive gear, the engagement depth of the drive gear can be reduced, thereby reducing torque loss.

[0014] Furthermore, due to the good form-locking connection between the force transmission component and the drive gear, there is no or only a very small transmission slippage.

[0015] The position of the force transmission component after pretensioning can be determined particularly well.

[0016] A separate retaining device for the force transmission element can be omitted, or the retaining device can be achieved by keeping the force transmission element continuously engaged with the drive gear after the seat belt tensioner is triggered.

[0017] Force transmission components are slender, flexible elements, especially rod-shaped polymers.

[0018] For example, the force transmission component is made of an elastic-plastic material.

[0019] In addition to the force transmission mechanism, the seatbelt tensioner also includes a gas generator that produces driving gas when the seatbelt tensioner is triggered.

[0020] According to one aspect, the drive gear is at least partially surrounded circumferentially by a guide device for a force-transmitting element, such that the force-transmitting element slides along the guide device after the seatbelt pretensioner is triggered, and is loaded radially toward the drive gear through the guide device. Here, the guide device controls the depth to which the drive gear engages with the force-transmitting element, thereby controlling the magnitude of the torque acting on the drive gear. This means that force transmission can be particularly controlled via a dedicated guide device. The guide device also serves, in particular, to keep the force-transmitting element engaged with the drive gear.

[0021] For example, the assembly includes an end stop for the force transmission element. This end stop ensures that the overload clutch is triggered even if the resistance of the seatbelt reel is very small, such as when the seatbelt reel can rotate freely or the seatbelt has a large slack. When the resistance is low, the force transmission element reaches the end stop at a high speed (e.g., above 20 m / s) and experiences a sudden, significant deceleration at the end stop. At this point, the load transmission direction from the force transmission element to the overload clutch reverses, and the overload clutch is triggered. Advantageously, the trigger torque of the overload clutch in the opposite direction is less than that in the drive direction because the overload clutch has been weakened by the previous load. That is, it disengages after a forward-backward movement.

[0022] The position of the end stop can also be used to limit the rotation angle of the drive gear.

[0023] Furthermore, the force transmitter is held within the assembly by an end stop after the seatbelt pretensioner is triggered, thus serving to seal the assembly, at least when the force transmitter is of sufficient length. This effectively prevents the drive gas from leaking out of the assembly in a simple manner.

[0024] According to one embodiment, the seatbelt pretensioner has a pressure tube in which a force-transmitting element is guided, wherein an end stop is disposed on the pressure tube, particularly on the outer side of the pressure tube. At high collision speeds, the pressure tube may deform due to the impact of the force-transmitting element, thereby increasing the frictional force acting on the portion of the force-transmitting element still located within the pressure tube. Therefore, the deceleration of the force-transmitting element is enhanced.

[0025] The end stop can be a separate component attached to the pressure tube. Alternatively, the end stop can be integrated into the pressure tube.

[0026] Preferably, the length of the force-transmitting element is greater than the circumference of the drive gear. This length is such that the force-transmitting element will not completely disengage from the pressure tube. In this way, a terminal stop is also achieved. In other words, at this length, the force-transmitting element locks itself in place after a relatively large rotation of the drive gear. Therefore, a separate terminal stop can be omitted. Furthermore, this length also achieves component sealing.

[0027] According to one embodiment, the force transmitter has a first section and a second section along the direction of movement of the force transmitter, wherein the first section has a larger diameter and / or less rigidity than the second section. Therefore, the torque transmitted from the force transmitter to the drive gear can increase with the increase of rotation of the drive gear. Because the first section has a larger diameter and / or less rigidity than the second section, the drive gear engages deeper into the first section of the force transmitter than into the second section. The frictional force acting on the second section is also reduced compared to the first section. In this way, once the drive gear engages with the second section, torque loss is reduced, thereby increasing the transmittable torque. Therefore, the reliability of triggering the overload clutch is further improved.

[0028] In an alternative embodiment, the seatbelt reel is capable of limited radial movement, and the drive gear is surrounded by a non-circular guide or support device that guides the radial movement of the seatbelt reel after the seatbelt tensioner is triggered, such that the depth to which the drive gear engages with the force transmission element decreases as the drive gear rotates. In this variation, the torque transmitted from the force transmission element to the drive gear also increases as the drive gear rotates. In particular, torque loss decreases with decreasing engagement depth, meaning that the transmitted torque increases.

[0029] For example, the non-circular guide device has a straight section directly opposite the pressure tube outlet of the seatbelt pretensioner and at least one arcuate section bordering the straight section. Therefore, immediately after the seatbelt pretensioner is triggered, when the force transmission element initially contacts the drive gear, the drive gear is first pressed against the straight section and bounced back on it, thus initially increasing the depth of penetration of the drive gear into the force transmission element. Then, the drive gear is guided along the arcuate section, thereby reducing the penetration depth again. Attached Figure Description

[0030] Further advantages and features of the present invention will become apparent from the following description and the accompanying drawings. The drawings show:

[0031] Figure 1 It is a seatbelt retractor that is part of the components of the present invention;

[0032] Figure 2yes Figure 1 The drive gear of the component shown;

[0033] Figure 3 yes Figure 1 The illustrated component of the present invention is shown as a side view after the seatbelt pretensioner has been triggered.

[0034] Figure 4 yes Figure 1 The illustrated component of the invention is shown as a side view at another point in time after the seatbelt pretensioner has been triggered;

[0035] Figure 5 A side view of a component of the invention according to an alternative embodiment is schematically shown;

[0036] Figure 6 A side view of a component of the invention according to another embodiment is schematically shown;

[0037] Figure 7 This is a side view of a component of the present invention according to yet another embodiment;

[0038] Figure 8 This is a side view of another component of the invention before the seatbelt pretensioner is triggered;

[0039] Figure 9 yes Figure 8 The component shown appears after the seatbelt pretensioner is triggered;

[0040] Figure 10 yes Figure 8 The components shown are at another point in time after the seatbelt pretensioner is triggered, and

[0041] Figure 11 yes Figure 8 The component shown is activated after the seatbelt pretensioner has fully engaged. Detailed Implementation

[0042] Figure 1 The image shows a seatbelt retractor 10, which has a frame 12 in which a seatbelt reel 14 is rotatably arranged.

[0043] Seat belts that can restrain vehicle occupants when needed can be stored on the seat belt reel 14. For simplicity, components such as locking mechanisms or retractor springs are not shown, as they are irrelevant to understanding the invention.

[0044] The seatbelt retractor 10 is provided with a seatbelt tensioner 16, which, in the example shown, has a pressure tube 18 and a force transmission element 20 (see...). Figure 3 It is stored in the pressure tube.

[0045] When the illustrated gas generator 22 is activated, the force transmission element 20 moves out of the pressure tube 18, causing it to mesh with and drive a drive gear 24. The drive gear 24 is torque-transmittingly engaged with the seatbelt reel 14. Therefore, when the seatbelt tensioner 16 is activated, the seatbelt reel 14 is driven in the winding direction.

[0046] The seat belt reel 14, seat belt tensioner 16, and drive gear 24 together constitute a separate component 11 of the seat belt retractor 10.

[0047] In the embodiment, the force transmission element 20 is a flexible plastic rod.

[0048] Figure 2 The drive gear 24 shown separately has a number of blades 26 on its outer side, which ensure frictional and form-locking connection with the force transmission element 20.

[0049] An overload clutch 28 is provided between the drive gear 24 and the seat belt reel 14. When a certain force threshold is exceeded, the overload clutch 28 is triggered, and the drive gear 24 is disengaged from the seat belt reel 14.

[0050] In this embodiment, the overload clutch 28 is implemented by a plurality of shearing elements 30, which are in the form of circular studs, and these shearing elements are inserted into corresponding holes 32 in the seat belt reel 14.

[0051] The shearing element 30 is designed as an integral part of the drive gear 24, and is formed together with the drive gear, for example, as a cold-extruded part.

[0052] Here, the shearing element 30 extends axially from the end face of the drive gear 24 facing the seat belt reel 14. Therefore, the hole 32 is located on the end face of the seat belt reel 14 facing the drive gear 24.

[0053] However, other types of overload clutches, such as overload clutches with friction discs, can also be considered.

[0054] Figure 3 and 4 Side views of the assembly 11 of the seatbelt retractor 10 are shown, respectively, showing the assembly 11 at different time points after the seatbelt tensioner 16 is triggered (i.e., in the state where the force transmission member 20 is acting on the drive gear 24).

[0055] exist Figure 3 and 4 As can be seen, the force transmission element 20 remains engaged with the drive gear 24 after the seatbelt pretensioner 16 is triggered. Therefore, the torque transmission to the drive gear 24 is improved.

[0056] The blade 26 of the drive gear 24 cuts into the force transmission element 20 and deforms it.

[0057] In this embodiment, the drive gear 24 is partially surrounded by the guide device 34 of the force transmission member 20 in the circumferential direction.

[0058] The guide device 34 is arranged such that the force transmission element 20 slides along the guide device 34 after the seat belt tensioner 16 is triggered and is loaded radially toward the drive gear 24 by the guide device 34.

[0059] In this embodiment, the guide device 34 is reinforced by the ribs 36.

[0060] The rib 36 is supported on the shell 37.

[0061] The pressure tube 18 has knurling 38, which creates increased friction on the force transmitter 20 within the area of ​​knurling 38. Therefore, the force transmitter 20 remains in the pressure tube 18 until the seatbelt pretensioner 16 is activated.

[0062] The overload clutch 28 should be able to be triggered at any position of the drive gear 24.

[0063] The greater the resistance on the seatbelt or seatbelt reel, the less rotation the drive gear 24 will make until it reaches the trigger torque.

[0064] The resistance depends on the length of the seat belt wound on the seat belt reel 14 and the slack of the seat belt or the pretension present on the seat belt.

[0065] The torque on the overload clutch 28 is mainly generated by subtracting the loss due to friction and deformation of the force transmission element 20 from the pressure of the driving gas generated by the gas generator 22.

[0066] If the force transmission element 20 moves slowly at the beginning due to high resistance, the gas pressure rises more forcefully, and the torque increases. This effect is significant when the gas volume is small, i.e., when the resistance has already risen forcefully shortly after the gas generator 22 is triggered.

[0067] This knowledge can be used to optimize the torque transmitted from the force transmitter 20 to the drive gear 24, and will be further combined with... Figures 7 to 11 This will be explained in more detail.

[0068] Figure 5 Another implementation of component 11 is shown. Figure 5 The components shown are Figure 1 , 3 The difference between component 11 shown in Figure 4 and component 4 is that it has a terminal stop 40.

[0069] When the force transmission element 20 contacts the end stop 40, the end stop stops the movement of the force transmission element. Therefore, the rotation angle of the drive gear 24 is also limited.

[0070] For the sake of simplicity, Figure 5 The guide device 34 is not shown in the diagram.

[0071] A retaining element 42 is fastened to one end of the force transmission element 20.

[0072] When the force transmission element 20 contacts the end stop 40, the retaining element 42 (particularly at the knurled 38) remains inserted in the pressure tube 18.

[0073] exist Figure 5 In the illustrated embodiment, the pressure tube is sealed by the retaining element 42.

[0074] According to Figure 3 and 4 In one embodiment, a corresponding retaining element 42 may also be provided.

[0075] Figure 6 Another embodiment of component 11 is shown, which differs in the shape of the terminal stop 40.

[0076] according to Figure 6 The terminal stop 40 is directly arranged on the knurled 38.

[0077] In particular, the terminal stop 40 is arranged on the outside of the pressure tube 18.

[0078] When the force transmission element 20 contacts the end stop 40, the knurling 38 is additionally deformed, thereby increasing the friction on the force transmission element 20.

[0079] exist Figure 6 In the embodiment shown, a portion of the force transmission element 20 is held in the pressure tube 18 and the pressure tube is sealed.

[0080] In this case, the length of the force transmission element 20 is greater than the circumference of the drive gear 24.

[0081] For added safety, a retaining element 42 may also be selected.

[0082] Figure 7 Another embodiment of component 11 of the present invention is shown.

[0083] Figure 7 The implementation methods shown are the same as Figure 3 and 4 The difference in the embodiment shown is the shape of the force transmission element 20.

[0084] Specifically, the force transmission member 20 has a first segment 44 along the direction of movement of the force transmission member 20 and a second segment 46 along the direction of movement of the force transmission member 20.

[0085] The first segment 44 has a diameter greater than and / or has a rigidity less than that of the second segment 46.

[0086] The first section 44 ensures that the drive gear 24 engages the force transmission member 20 with sufficient depth, thereby enabling sufficient torque transmission with very low slippage immediately after the seat belt tensioner 16 is triggered.

[0087] Within the region of the second section 46, the engagement depth of the drive gear 24 in the force transmission member 20 is less than that in the first section. Furthermore, the frictional force in the pressure tube 18 of the second section is less than that of the first section. Therefore, once the second section 46 engages with the drive gear 24, torque loss is reduced. Consequently, the transmittable torque increases, thereby reliably triggering the overload clutch 28.

[0088] Figures 8 to 10 Another component 11, which is also optimized for torque transmission, is shown at different time points after the gas generator 22 is triggered. Figures 8 to 11 In the diagram, the force transmission element 20 is shown in a transparent manner, with its outline represented by dashed lines.

[0089] Figure 8 The component 11 before the gas generator 22 is triggered is shown.

[0090] In this embodiment, the seatbelt reel 14 of component 11 can move radially in a limited manner, such as by adjusting the... Figures 8 to 11 As clearly visible as possible.

[0091] The drive gear 24 is surrounded by a non-circular guide 48, which guides the radial movement of the seatbelt reel 14 after the seatbelt tensioner 16 is triggered, such that the depth of the drive gear 24 engaging the force transmission element 20 decreases as the drive gear 24 rotates. Due to the reduced engagement depth, torque loss is also reduced, thereby increasing the transmitted torque.

[0092] The non-circular guide device 48 has a straight section 50 that is directly opposite the outlet 52 of the pressure tube 18 of the seat belt tensioner 16.

[0093] The straight section 50 is inclined at an angle α of 30° to 40° with the discharge direction of the force transmission element 20 from the pressure tube 18.

[0094] In addition, the guide device also has an arc-shaped section 54 that connects with the straight section 50.

[0095] like Figure 9 As shown, when the seatbelt pretensioner 16 is triggered, the force transmission element 20 contacts the drive gear 24, which is then loaded toward the straight section 50 and springs back on that section, thereby pressing the blades 26 of the drive gear 24 into the force transmission element 20. Therefore, reliable torque transmission is achieved with very low slippage in the early stages after the gas generator is triggered.

[0096] When the two blades 26 engage with the transmission member 20, the drive gear 24 or the seat belt reel 14 is lifted again, and the drive gear 24 slides along the straight section 50.

[0097] When the drive gear 24 rotates further via the movement of the transmission member 20, the force transmission member 20 presses between the drive gear 24 and the linear section 50, such as... Figure 10 As shown.

[0098] Therefore, the drive gear 24 is guided along the arcuate section 54. The depth of each individual blade 26 entering the force transmission element 20 is thus reduced, thereby increasing the transmitted torque.

[0099] In particular, the seatbelt reel 14 reaches its highest position after rotating about 100°, especially 90° to 110°, thereby reducing the cutting depth.

[0100] Figure 11 The force transmission element 20 is shown in its final position after the gas generator 22 is triggered.

[0101] In this case, the length of the force transmission element 20 is greater than the circumference of the drive gear 24, so that the force transmission element 20 itself constitutes an end stop.

Claims

1. An assembly (11) for a seatbelt retractor (10) for a motor vehicle, the assembly comprising a seatbelt reel (14), a seatbelt tensioner (16) and a drive gear (24) torque-transmittingly engaged with the seatbelt reel (14), and a force-transmitting element (20) of the seatbelt tensioner (16) acting on the drive gear to drive the seatbelt reel (14) in the retraction direction of the seatbelt, wherein an overload clutch (28) is provided between the drive gear (24) and the seatbelt reel (14), and the force-transmitting element (20) remains continuously engaged with the drive gear (24) after the seatbelt tensioner (16) is triggered.

2. The component (11) according to claim 1, characterized in that: The drive gear (24) is at least partially surrounded in the circumferential direction by a guide (34) for the force transmission element (20), such that the force transmission element (20) slides along the guide (34) after the seat belt tensioner (16) is triggered, and is loaded radially toward the drive gear (24) through the guide (34).

3. The component (11) according to any one of the preceding claims, characterized in that: The component (11) is provided with a terminal stop (40) for the force transmission element (20).

4. The component (11) according to claim 3, characterized in that: The seatbelt tensioner (16) has a pressure tube (18) in which a force transmission element (20) is guided, wherein an end stop (40) is provided on the pressure tube (18), particularly on the outside of the pressure tube (18).

5. The component (11) according to any one of the preceding claims, characterized in that: The length of the force transmission element (20) is greater than the circumference of the drive gear (24).

6. The component (11) according to any one of the preceding claims, characterized in that: The force transmission member (20) has a first segment (44) along the direction of movement of the force transmission member (20) and a second segment (46) along the direction of movement of the force transmission member (20), wherein the first segment (44) has a larger diameter and / or less rigidity than the second segment (46).

7. The component (11) according to any one of claims 1 to 6, characterized in that: The seat belt reel (14) is capable of limited radial movement, and the drive gear (24) is surrounded by a non-circular guide or support device (48) that guides the radial movement of the seat belt reel (14) after the seat belt tensioner (16) is triggered, such that the depth of the drive gear (24) in the force transmission element (20) decreases as the rotation of the drive gear (24) increases.

8. The component (11) according to claim 7, characterized in that: The non-circular guide device (48) has a straight section (50) directly opposite the outlet (52) of the pressure tube (18) of the seat belt tensioner (16) and at least one arcuate section (54) connected to the straight section (50).

Images