WO2012156019A1

WO2012156019A1 - Force limiting device for a motor vehicle and belt retractor

Info

Publication number: WO2012156019A1
Application number: PCT/EP2012/001728
Authority: WO
Inventors: Klaus-Peter Singer; Ronald Jabusch
Original assignee: Autoliv Development Ab
Priority date: 2011-05-13
Filing date: 2012-04-21
Publication date: 2012-11-22
Also published as: DE102011101517B4; DE102011101517A1

Abstract

The invention relates to a force limiting device (4) for a motor vehicle, which has at least two parts (5, 11) which are controlled relative to one another with a movement defined according to frequency, wherein the parts (5, 11) which move relative to one another have interengaging toothings (10, 18) and the movement controlled according to frequency is carried out in such a way that at least one of the parts (5, 11) performs an advancing movement (V) relative to the other part (5, 11) with an undulating movement (Q) directed transversely with respect to the advancing movement (V), and during said movement the toothings (10, 18) are alternately engaged and disengaged, wherein a device for changing the depth of engagement (T) of the toothings (10, 18) is provided on the force limiting device (4).

Description

Power limiting device for a motor vehicle and belt retractor

The invention relates to a force limiting device for a motor vehicle and a belt retractor having the features of one of the preambles of one of claims 1 or 8.

From WO 2006/108451 Al, e.g. a speed-controlled Kraftbegrerizungseinrichtung 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 10 2008 049 931.5 a further developed, based on 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 in Engaging and disengaging. The oscillating masses are replaced by the part which carries out the wavelike feed motion, so that the force limiting device described therein requires a considerably smaller installation 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 is given by the kinetic energy of the occupant to be degraded during the forward displacement automatically, the basic characteristic being determined by the parameters of the gear disc, such as e.g. 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 overlapping of the teeth during the intervention can be changed, by which the destroyed in the Kraftbegrenzungs- device destroyed energy and thus the force limiting level with. 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 of a for the installation or the

Motor vehicle corresponds to optimal or predetermined force limiting characteristic. 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 e.g. in the case of force limiting devices in belt - wounders, progressive or degressive force - limiting processes should be implemented in which the force - limiting level is 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. 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 determine critical conditions from signals relating to vehicle dynamics and parameters relating to the vehicle environment, such as the distances to vehicles in front or other obstacles, as a result of which measures to increase occupant safety can be taken at an early stage. Since these signals are available early before the actual accident situation occurs, can the power limiting device thereby already be adjusted so far before the accident in each case in the force limiting characteristic that it has an ideal for a subsequent accident accidental force limiting characteristic.

A particularly fast activation with very large adjusting forces can be achieved, for example, by be achieved by the actuator is formed by a piezo element or a piezo stack. Piezo stacks, or else "piezo stacks", are preferably provided in this respect insofar as the adjustment path and also the adjusting force can be increased by the use of a multiplicity of piezo elements arranged in the form of a piezo stack.

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 e.g. a small actuating force is converted in a large actuating travel in a large adjusting force at a small displacement of the toothed part.

Further, to achieve the object, a belt retractor with a force limiting device according to one of claims 1 to 7 for enabling a force-limited belt webbing with-a 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 in Gurtauszugsrichtung proposed, wherein the force limiting device is set during activation with blocked Gurtwelle with a part on the retractor frame, and with the other part is connected to 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 Kraftbegrenzungs- device by the proposed assignment of parts immediately upon blocking the belt shaft comes into 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. Due to the suggested training 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 punctiform loading.

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 adjustment movement with the lowest 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:

Fig. 1: belt retractor with a force limiting device;

2: retractor frame with an annular toothed disc;

Fig. 3: retractor frame with an annular actuator; Fig. 4: actuator and gear disc; 5 shows a detail of a belt retractor with a force limiting device in a sectional view before the actuation of the actuating element;

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

7 shows a detail of a belt retractor with a force limiting device before actuation of the actuating element in an oblique view;

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

Fig. 9: Enlarged section of the interlocking

Gearing.

FIG. 1 shows a belt retractor 1 with a belt shaft 2 rotatably mounted in a roller frame 3. On the retractor frame 3, an annular force limiting device 4 is further provided, through which the belt shaft 2 extends centrally therethrough. The force limiting device 4 has a device for a change in the force limiting characteristic described below, which comprises an actuating part 6 with a radially projecting actuating section 8 and an actuator 16 coupled to the actuating section 8 via an adjusting rod 17. The actuator 16 is fixedly attached to the retractor frame 3 and comprises an externally controllable piezo stack. Instead of the piezostack However, the actuator 16 may also include a pyrotechnic propellant, a pressure medium source or an electromechanical adjustment, the piezo stack is particularly advantageous in that it is particularly well controlled, ie it can be realized very precise adjustment with large adjustment forces.

In the figure 2, 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 can be seen.

In the figure 3, the same retractor frame 3 can be seen, in which the part 5 has been removed. In the figure 4, the part 5 and the actuating part 6 are shown as individual parts. On the part 5 and on the actuating part 6, a plurality of annularly arranged ramps 7 and 9 are respectively provided on the axial sides, which each form a ramp contour, with which the part 5 and the actuating part 6 abut one another. The ramps 9 on the part 5 and the ramps 7 on the actuating part 6 each have an identical pitch and are directed opposite, so that in the abutment of the part 5 on the actuating part 6 a parallel alignment of the part 5 to the actuating part. 6 enable.

FIGS. 5 and 6 each show a sectional view in a sectional plane through the force limiting device with two different positions of the part 5.

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 projects with a ring-cylindrical toothed ring 12 and which comprises the belt shaft 2 concentrically. Of the Gear ring 12 is radially inwardly provided with a toothing 13, in which the belt shaft 2 by means of a blocking device, formed by a mounted on the belt shaft locking pawl, can be blocked in Gurtauszugsrichtung. On the toothed ring 12, a multi-tooth profile 14 is provided on the radial outer side, on which a part 11 in the form of a vibrating plate is displaceably guided in the axial direction and at the same time is positively connected in the circumferential direction. On the part 11, an annular axially directed toothing 18 is provided with radially directed tooth flanks, which is arranged on the part 5 facing side of the part 11.

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

The entire force limiting device 4 is covered with a housing 15 which engages with spaced fingers 26 in openings 25 on the retractor frame 3, whose dimensions correspond in the circumferential direction of the width of the fingers 26. The housing is thus fixed against rotation on the retractor frame 3. In addition, 26 openings 22 are provided at the ends of the fingers, in which a system cap 24 engages with radially directed projections 23, so that the housing 15 is secured together with the system cap 24 in the withdrawal direction of the retractor frame 3. The actuating member 6 is also provided with openings 27 through which the fingers 26 passed are, but which have a greater width than the fingers 26, so that the actuating member 6 can be slightly rotated. The part 5 has radially outwardly directed extensions 20, between which recesses 21 are formed. The extensions 20 have a width which is identical to the width of the free spaces formed between the fingers 26, so that the extensions 20 protrude into the free spaces between the fingers 26 and in the circumferential direction bear against the fingers 26 in a form-fitting manner. The part 5 is thereby rotationally fixed to the housing 15 and relative to the actuating part 6.

Upon activation of the force limiting device 4 by blocking the belt shaft 2 in the toothed ring 12 and exceeding a predetermined by the design of the force limiting device force threshold of the toothed ring 12 and the part 11 are driven by the rotational movement of the belt shaft 2 in Gurtauszugsrichtung. Since the teeth 10 and 18 mesh with each other at the beginning of the activation of the force limiting device 4, the part 11 in addition to the rotational feed motion V by sliding together the tooth flanks, as can be seen in Figure 9, to a transverse to the feed motion V directed wave motion Q driven, during which the part 11 is braked and accelerated periodically. 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 momentary force limitation level is the transverse direction forced by the sliding of the tooth flanks Shaft movement Q, which is determined directly by the maximum engagement depth T of the teeth 10 and 18.

This engagement depth T can be changed on the basis of the solution according to the invention, in that the actuator 16 rotates the actuating part 6 via the adjusting rod 17 and the actuating portion 8 during a drive. As a result of the rotation of the actuating part 6 in the direction of arrow A from the position shown in FIG. 7 into the position shown in FIG. 8, the part 5 moves axially in the direction of the arrow 11 due to the ramps 7 and 9 sliding away from each other (see FIG. 9). shifted, whereby the engagement depth T of the teeth is increased. In the case of the engagement depth T, the amount of change in the engagement depth T should therefore be understood in the sense of the invention as meaning that the engagement depth T always means the maximum engagement depth T during the wave movement.

The engagement depth T can be set manually once before or after installation in the motor vehicle so that the force-limiting characteristic can be individually adapted to the motor vehicle. Alternatively, the engagement depth T can also be changed depending on the respective occupant to be restrained or the respectively sensed subsequent accident situation prior to the activation of the force limiting device 4. 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 take place during the activation of the force limiting device 4, whereby nonlinear force limiting characteristics, such as progressive or degressive force limiting characteristics, can be realized.

Since the actuating part 6 is supported at the rear on one leg of the retractor frame 3, the reaction forces generated during the adjustment of the part 5 can be introduced over a large area into the retractor frame 3. Overall, the required space is increased by the device only by the force limiting device 4 is increased by the thickness of the operating part 6, and, if an external control is to be provided, a corresponding space for the actuator 16 must be present.

Claims

Claims :

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

Second 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 tooth depth of the teeth (10,18) is variable.

3. force limiting device (4) according to one of the preceding claims, characterized in that the device is adapted to change the engagement depth (T) of the toothings (10,18) during the activation of the force limiting device (4).

4. force limiting device (4) according to one of the preceding claims, characterized in that the device comprises an externally controllable actuator (16).

5. power limiting device (4) according to claim 4, characterized in that the actuator (16) can be controlled by a driver assistance system.

6. force limiting device (4) according to claim 4 or 5, characterized in that the actuator (16) is formed by a piezoelectric element or a piezoelectric stack.

7. force limiting device (4) according to one of the preceding claims, characterized in that the device comprises an actuating part (6) which rests on one of the parts (5,11) via 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).

8. belt retractor (1) with a force limiting device (4) according to one of claims 1 to 7 for enabling a force-limited belt webbing with

one in a retractor frame (3) rotatably mounted belt shaft (2), and

a blocking device for blocking the belt shaft (2) when exceeding a predetermined value of Gurtbandausausbeschleunigung and / or the vehicle deceleration with respect to the retractor frame (3) in Gurtauszugsrichtung, characterized in that

the force limiting device (4) is fixed to the retractor frame (3) with one part (5) during activation when the belt shaft (2) is locked, and is connected to the belt shaft (2) with the other part (11).

9. belt retractor (1) according to claim 8, characterized in that the device on the retractor frame (3) off supports.

10. The 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-shaped contour on the annular toothed disc.

11. The belt retractor (1) according to claim 10, characterized in that the adjustable ring is arranged such that it is supported during the adjusting movement of the retractor frame (3).

12. The belt retractor (1) according to claim 10 or 11, characterized in that on the toothed disc a counter to the ramp contour of the adjustable ring directed second ramp contour is provided, against which the adjustable ring rests with the ramp contour.