DE102011101517B4 - Force limiting device for a motor vehicle and belt retractor - Google Patents

Abstract

Force limiting device (4) for a motor vehicle, which has at least two parts (5, 11) controlled relative to each other with a frequency-dependent movement, wherein the relatively moving parts (5, 11) intermeshing teeth (10, 18) and the frequency-related controlled movement takes place in that at least one of the parts (5, 11) relative to the other part (5, 11) performs an advancing movement (V) with a transversely to the advancing movement (V) directed wave motion (Q), in which the teeth ( 10, 18) alternately engage and disengage, characterized in that a device for changing the engagement depth (T) of the toothings (10, 18) is provided on the force limiting device (4).

Description

The invention relates to a force limiting device for a motor vehicle having the features of the preamble of claim 1 and a belt retractor with a force limiting device.

From the WO 2006/108 451 A1 is z. B. a speed-controlled force limiting device for a belt retractor, which has a plurality of arranged on the frame of the belt retractor to be vibrated masses. The masses are rotatably mounted on the retractor frame and engage during the force-limited belt webbing alternately with two teeth in a toothed ring connected to the belt shaft. Overall, the belt retractor due to the arranged on the retractor vibrating masses consuming in the production and expensive. Furthermore, the belt retractor requires due to the oscillating masses a relatively large amount of space.

In the German patent application DE 10 2008 049 931 A1 a further developed, on the basis of the same physical principle working force limiting device is described, in which two parts are moved with the teeth force-limited to each other and one of the parts doing a wavy feed motion, in which the gears alternately engage and disengage. By the wave-like feed movement exporting part, the oscillating masses are replaced, so that the force limiting device described therein requires a much smaller space and has a much simpler structure. In one embodiment, the wavy feed movement exporting part is realized by a toothed disc, which is non-positively connected to the belt shaft.

The level of the force limiting device results automatically by the degraded kinetic energy of the occupant during the forward displacement, the basic characteristic by the parameters of the gear disc, such as. As the number of teeth, the tooth spacing or the mass of the toothed disc is fixed.

A disadvantage of these force limiting devices is that the basic characteristic of the force limitation curve of the finished force limiting device is fixed once because of the parameters that are no longer to be changed. In certain applications, however, it may be necessary to subsequently adapt the basic characteristic of the force limitation curve of the force limiting device to the motor vehicle individually. Since this is not possible with a generic force limiting device, the force limiting device must be adapted individually in the design according to the vehicle-specific requirements. Furthermore, it is not possible to fine-tune the basic characteristic of the force limitation curve to the type of occupant to be detained and the accident situation.

The object of the invention is to provide a generic force limiting device in which the basic characteristic of the force limiting curve can be subsequently changed with the simplest possible means.

To achieve the object, a force limiting device according to the invention with the features of claim 1 is proposed. Further preferred embodiments of the invention are given in the dependent claims the figures and the associated description.

According to the basic idea of the invention, it is proposed that a device for changing the engagement depth of the toothings is provided on the force limiting device. By changing the depth of engagement of the teeth, the degree of overlap of the teeth can be changed during the intervention, by which the destroyed in the force limiting device energy and thus the force limiting level is determined. Furthermore, the transverse movement portion of the undulating feed movement can thereby be changed, which forms a decisive proportion of the feed movement. As a result of this modified transverse movement component, the feed movement and thus the belt pull-out speed can be changed during the activation of the force limiting device, in such a way that the belt pull-out speed decreases as the engagement depth increases and increases as the engagement depth is reduced. The force limiting device can thereby be adapted to the individual motor vehicle or the individual installation location even after assembly, that the force limiting characteristic corresponds to an optimal or predetermined force limiting characteristic for the installation location or the motor vehicle. As a result, the force limiting device can initially be produced uniformly in large numbers and can only be subsequently adapted to the individual use.

From experiments it has been found that a particularly effective change of the force limiting characteristic can be achieved if the depth of engagement in the range of 0.2 to 0.7 times the tooth depth of the teeth can be changed.

It is also proposed that the device is set up to change the engagement depth of the teeth during activation of the force limiting device. The proposed design of the force limiting device, the force limiting characteristic can also be changed during activation, so that in particular non-linear force limiting profiles can be realized. This can be z. B. in force limiting devices in belt retractors may be required if progressive or degressive force limiting curves are to be implemented, in which the force limiting level to rise or fall abruptly.

It is further proposed that the device comprises an externally controllable actuator. Due to the externally controllable actuator, the force limiting characteristic can be active, i. H. also depending on the situation, be changed.

It is further proposed that the actuator can be controlled by a driver assistance system. Driver assistance systems are understood to be systems which include signals relating to vehicle dynamics and parameters relating to the vehicle environment, such as, for example, vehicle dynamics. B. determine the distances to vehicles in front or other obstacles, critical conditions, which early measures to increase the occupant safety can be taken. Since these signals are available early before the occurrence of the actual accident situation, the force limiting device can thereby be adjusted before the accident in each case far enough in the force limiting characteristic that this has an ideal for a subsequent accident accidental force limiting characteristic.

A particularly fast control with very large adjusting forces can, for. B. be achieved by the actuator is formed by a piezo element or a piezo stack. Piezo stack, or also called "piezo stack", offer themselves here preferably in so far as can be increased by the use of a plurality of mutually arranged piezoelectric elements in the form of a piezoelectric stack of the adjustment and the adjustment.

It is further proposed that the device comprises an actuating part which rests on one of the parts via a ramp contour and is adapted to carry out a relative movement to the part for changing the engagement depth of the teeth. Due to the ramp contour, the adjusting movement and the actuating direction of the actuating part can be directed differently, so that both directions can be ideally designed for handling and the force effect. Furthermore, a kind of translation can be created by the ramp contour, by means of which z. B. a small actuation force is converted at a large actuation path in a large adjustment force at a small displacement of the toothed portion provided.

• – einer in einem Aufrollerrahmen drehbar gelagerten Gurtwelle, und
• – einer Blockiervorrichtung zum Blockieren der Gurtwelle bei Überschreiten eines vorgegebenen Wertes der Gurtbandauszugsbeschleunigung und/oder der Fahrzeugverzögerung gegenüber dem Aufrollerrahmen in Gurtauszugsrichtung vorgeschlagen, wobei
• – die Kraftbegrenzungseinrichtung während der Aktivierung bei blockierter Gurtwelle mit einem Teil an dem Aufrollerrahmen festgelegt ist, und mit dem anderen Teil mit der Gurtwelle verbunden ist. Der vorgeschlagene Gurtaufroller kann durch die darin angeordnete erfindungsgemäß ausgebildete Kraftbegrenzungseinrichtung mit einer für den Insassen optimalen Rückhaltecharakteristik versehen werden, wobei die Kraftbegrenzungseinrichtung durch die vorgeschlagene Zuordnung der Teile unmittelbar beim Blockieren der Gurtwelle zur Wirkung gelangt. Ferner kann durch die vorgeschlagene Zuordnung der Teile ein Gurtaufroller mit einem sehr geringen Bauraumbedarf bereitgestellt werden.

Further, to solve the problem, a belt retractor with a force limiting device according to one of claims 1 to 7 for enabling a force-limited belt webbing with

• - One in a retractor frame rotatably mounted belt shaft, and
• - A blocking device for blocking the belt shaft when exceeding a predetermined value of Gurtbandauszugsbeschleunigung and / or the vehicle deceleration with respect to the retractor frame in Gurtauszugsrichtung suggested, wherein
• - The force limiting device is set during activation with blocked belt shaft with a part on the retractor frame, and is connected to the other part of the belt shaft. The proposed belt retractor can be provided by the force limiting device arranged therein according to the invention with an optimum for the occupant retention characteristic, wherein the force limiting device passes through the proposed assignment of parts immediately upon blocking the belt shaft to the effect. Furthermore, a belt retractor with a very small space requirement can be provided by the proposed assignment of the parts.

It is also proposed that the device be supported on the retractor frame. By supporting the device on the retractor frame, the reaction forces arising upon actuation of the device can be introduced in a structurally simple manner via the retractor frame into the vehicle structure. Furthermore, the belt retractor can thereby be delivered as a preassembled unit to the vehicle manufacturer and mounted on the motor vehicle.

It is also proposed that the wave-shaped feed movement exporting part is formed by an annular toothed disc, which performs a rotational feed movement during the force-limited Gurtbandauszugsbewegung and the actuating member is formed by a rotatably adjustable ring which rests on the ramp contour on the annular toothed disc. The proposed design of the force limiting device and the matching training of the operating part as a rotatably adjustable ring which rests on the ramp contour on the toothed disc, the optimized for the belt retractor force limiting device can be easily operated. The actuating part transmits the adjusting force over the entire circumference and uniformly on the toothed ring so that it can not tilt or can be damaged by a punctual load.

The adjustable ring is preferably arranged such that it is supported during the adjustment movement for receiving the reaction forces on the retractor frame.

A particularly uniform adjusting movement with the least possible loading of the interacting parts can be achieved in this case by providing on the toothed disc a counter to the ramp contour of the adjustable ring second ramp contour is provided on which rests the adjustable ring with the ramp contour.

The invention will be explained below with reference to a preferred embodiment with reference to the accompanying figures. Showing:

1 : Belt retractor with a force limiting device;

2 : Retractor frame with an annular gear disc;

3 : Retractor frame with an annular actuator;

4 : Actuator and gear disc;

5 : Section of a belt retractor with a force limiting device in a sectional view before the actuation of the actuating element;

6 : Section of a belt retractor with a force limiting device in a sectional view after the actuation of the actuating element;

7 : Section of a belt retractor with a force limiting device prior to actuation of the actuating element in an oblique view;

8th : Section of a belt retractor with a force limiting device after actuation of the actuating element in an oblique view; and

9 : Enlarged section of interlocking gears.

In the 1 is a belt retractor 1 with one in a retractor frame 3 rotatably mounted belt shaft 2 to recognize. On the retractor frame 3 is also an annular force limiting device 4 provided by the belt shaft 2 protrudes centrically. The force limiting device 4 has a device for a change in the force limiting characteristic described below, which is an actuating part 6 with a radially projecting actuating portion 8th and one via an adjustment rod 17 to the operating section 8th coupled actuator 16 includes. The actuator 16 is fixed to the retractor frame 3 attached and includes an externally controllable piezo stack. Instead of the piezo stack, the actuator can 16 but also include a pyrotechnic propellant charge, a pressure medium source or an electromechanical adjustment unit, wherein the piezo stack is insofar of particular advantage, since it is particularly well controlled, ie it can be realized very precise adjustment with simultaneous large adjustment forces.

In the 2 is the retractor frame 3 with the actuating part 6 and a part 5 in the form of an annular toothed disc with an axially directed toothing 10 to recognize.

In the 3 is the same retractor frame 3 to recognize where the part 5 was removed. In the 4 are the part 5 and the operating part 6 shown as individual parts. At the part 5 and on the actuating part 6 are at the axial sides in each case a plurality of annularly arranged ramps 7 and 9 provided, each forming a ramp contour with which the part 5 and the operating part 6 abut each other. The ramps 9 at the part 5 and the ramps 7 on the actuating part 6 each have an identical pitch and are directed opposite, so they are in the plant of the part 5 on the actuating part 6 a parallel alignment of the part 5 to the operating part 6 enable.

In the 5 and 6 is in each case a sectional view in a sectional plane through the force limiting device with two different positions of the part 5 to recognize.

The belt shaft 2 protrudes through an opening in one of the legs of the U-shaped retractor frame 3 into which the force limiting device 4 with a ring-cylindrical toothed ring 12 protrudes into it and the belt shaft 2 concentrically. The gear ring 12 is radially inward with a toothing 13 provided in the belt shaft 2 by means of a blocking device, formed by a locking pawl mounted on the belt shaft, can be blocked in the belt extension direction. On the gear ring 12 is on the radial outside a multi-tooth profile 14 provided on the part 11 is guided displaceably in the axial direction in the form of a vibrating plate and is simultaneously positively connected in the circumferential direction. At the part 11 is an annular axially directed toothing 18 with radially directed tooth flanks provided, which at the part 5 facing side of the part 11 is arranged.

Further, on the retractor frame 3 the annular actuating part 6 with the axially directed ramps 7 arranged at which the part 5 with the ramps 9 is applied. The part 5 is as a toothed ring with an axially directed toothing 10 trained and parallel to the part 11 aligned. The parts 5 and 11 are before the activation of the force limiting device in such a position to each other that the teeth 10 and 18 mesh.

The entire force limiting device 4 is with a housing 15 covered, which with spaced fingers 26 in openings 25 on the retractor frame 3 engages whose dimensions in the circumferential direction of the width of the fingers 26 correspond. The housing is thereby rotationally fixed to the retractor frame 3 established. Also, at the ends are the fingers 26 openings 22 provided in the one system cap 24 with radially directed extensions 23 engages, leaving the case 15 together with the system cap 24 in the withdrawal direction on the retractor frame 3 is secured. The actuating part 6 is also with openings 27 provided by the fingers 26 passed through, but which have a greater width than the fingers 26 have, so that the actuating part 6 can be slightly twisted. The part 5 has radially outward extensions 20 on, between which recesses 21 are formed. The extensions 20 have a width which is identical to the width of the one between the fingers 26 formed free spaces, so that the extensions 20 into the spaces between the fingers 26 protrude and thereby positively in the circumferential direction on the fingers 26 issue. The part 5 is thereby on the housing 15 and opposite the operating part 6 fixed against rotation.

Upon activation of the force limiting device 4 by blocking the belt shaft 2 in the toothed ring 12 and exceeding a force threshold given by the design of the force limiting device becomes the toothed ring 12 and the part 11 by the rotation of the belt shaft 2 driven in Gurtauszugsrichtung. Because the gears 10 and 18 at the beginning of activation of the force limiting device 4 Intertwine becomes the part 11 in addition to the rotational feed motion V by sliding together the tooth flanks, as in the 9 can be seen, to a transverse to the feed movement V directed wave motion Q driven while the part 11 periodically decelerated and accelerated. This periodic deceleration and acceleration of the part 11 is the physical cause of the speed-controlled force limiting device 4 underlying energy destruction.

An essential parameter for the degree of energy destruction and thus for the current force limitation level is the transverse wave motion Q, which is forced by the sliding of the tooth flanks and which is directly caused by the maximum engagement depth T of the toothings 10 and 18 is determined.

This engagement depth T can be changed due to the inventive solution by the actuator 16 when activated, the actuating part 6 over the adjusting rod 17 and the operation section 8th twisted. By the rotation of the operating part 6 in the direction of arrow A from in the 7 shown position in the in 8th shown position becomes the part 5 due to the ramps sliding off each other 7 and 9 axially in the direction of the part 11 in the direction of the arrow Z (see 9 ), whereby the engagement depth T of the gears is increased. The depth of engagement T is a measure which changes during the wave movement; the term of change of the engagement depth T should therefore be understood in the sense of the invention as meaning the depth of engagement T always means the maximum depth of engagement T during the wave movement.

The engagement depth T can be adjusted manually once before or after installation in the motor vehicle so that the force limiting characteristic can be adapted individually to the motor vehicle. Alternatively, the engagement depth T can also be dependent on the respective occupant to be restrained or the respective sensed subsequent accident situation prior to the activation of the force limiting device 4 to be changed. In particular, the signal of a driver assistance system offers itself, since these signals are available early on even before the occurrence of the accident situation.

Furthermore, the adjustment of the engagement depth T can also during the activation of the force limiting device 4 done whereby non-linear force limiting characteristics such. B. progressive or degressive force limiting curves, can be realized.

As the actuating part 6 rearward on one leg of the retractor frame 3 can be supported when adjusting the part 5 generated reaction forces over a large area in the retractor frame 3 be initiated. Overall, the required space is increased by the device only by the force limiting device 4 around the thickness of the operating part 6 is increased, and, if an external control is to be provided, a corresponding space for the actuator 16 must be present.

Claims (12)

Force limiting device ( 4 ) for a motor vehicle which has at least two parts controlled relative to each other with a frequency-dependent defined movement ( 5 . 11 ), wherein the relatively moving parts ( 5 . 11 ) interlocking gears ( 10 . 18 ) and the frequency-dependent controlled movement takes place in that at least one of the parts ( 5 . 11 ) compared to the other part ( 5 . 11 ) performs an advancing movement (V) with a transverse to the feed movement (V) directed wave motion (Q), in which the toothings ( 10 . 18 ) alternately engage and disengage, characterized in that at the force limiting device ( 4 ) means for changing the engagement depth (T) of the teeth ( 10 . 18 ) is provided. Force limiting device ( 4 ) according to claim 1, characterized in that the engagement depth in the range of 0.2 to 0.7 times the toothing depth of the teeth ( 10 . 18 ) is changeable. Force limiting device ( 4 ) according to one of the preceding claims, characterized in that the device is adapted to the engagement depth (T) of the teeth ( 10 . 18 ) during activation of the force limiting device ( 4 ) to change. Force limiting device ( 4 ) according to one of the preceding claims, characterized in that the device has an externally controllable actuator ( 16 ). Force limiting device ( 4 ) according to claim 4, characterized in that the actuator ( 16 ) can be controlled by a driver assistance system. Force limiting device ( 4 ) according to claim 4 or 5, characterized in that the actuator ( 16 ) is formed by a piezo element or a piezo stack. Force limiting device ( 4 ) according to one of the preceding claims, characterized in that the device comprises an actuating part ( 6 ) which is attached to one of the parts ( 5 . 11 ) rests on a ramp contour and is adapted to change the engagement depth (T) of the teeth ( 10 . 18 ) a relative movement to the part ( 5 . 11 ). Belt retractor ( 1 ) with a force limiting device ( 4 ) according to one of claims 1 to 7 for enabling a force-limited belt webbing extension - one in a retractor frame ( 3 ) rotatably mounted belt shaft ( 2 ), and - a blocking device for blocking the belt shaft ( 2 ) when a predetermined value of the webbing extension acceleration and / or the vehicle deceleration with respect to the retractor frame ( 3 ) in Gurtauszugsrichtung, wherein - the force limiting device ( 4 ) during activation with blocked belt shaft ( 2 ) with a part ( 5 ) on the retractor frame ( 3 ) and with the other part ( 11 ) with the belt shaft ( 2 ) connected is. Belt retractor ( 1 ) according to claim 8, characterized in that the device on the retractor frame ( 3 ) is supported. Belt retractor ( 1 ) according to claim 7 and one of claims 8 or 9, characterized in that the wave-shaped feed movement exporting part ( 11 ) is formed by an annular toothed disc, which performs a rotational feed movement (V) during the force-limited Gurtbandauszugsbewegung, and the actuating part ( 6 ) is formed by a rotatably adjustable ring, which rests on the ramp tooth contour on the annular toothed disc. Belt retractor ( 1 ) according to claim 10, characterized in that the adjustable ring is arranged such that it during the adjusting movement of the retractor frame ( 3 ) is supported. Belt retractor ( 1 ) according to claim 10 or 11, characterized in that on the toothed disc a to the ramp contour of the adjustable ring directed counter to the second ramp contour is provided, against which the adjustable ring rests with the ramp contour.

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