SAFETY BELT DEVICE FOR A VEHICLE

Abstract

A safety belt arrangement for a vehicle, with a belt force limiting unit which is constructed as a piston/cylinder assembly having a piston tube and a piston, which in the event of the belt force being limited is displaceable by a force limiting path in the piston tube, while expanding and plastically deforming the latter, whereby the belt force exerted on a vehicle occupant is limited to a predefined level of force. According to the invention, at least one tube element, which can be pushed telescopically onto the piston tube to form a double tube structure, is provided for setting the force level course over the force limiting path.

Claims

1. A safety belt arrangement for a vehicle, comprising: a belt force limiting unit that is constructed as a piston/cylinder assembly having a piston tube and having a piston, which in an event of a belt force being limited is displaceable in the piston tube about a force limiting path while expanding and plastically deforming the tube, the belt force exerted on a vehicle occupant being limited to a predefined force level; and at least one tube element to set a force level course over the force limiting path, the at least one tube element being adapted to be pushed telescopically onto the piston tube to form a double tube structure.

2. The safety belt arrangement according to claim 1, wherein a tube length of the tube element less than a tube length of the piston tube, so that the piston tube has at least one tube section enclosed by the tube element and at least one tube section not covered by the tube element.

3. The safety belt arrangement according to claim 1, wherein an inner diameter of the tube element is greater than an outer diameter of the piston tube by a slight play, and/or that in particular the tube element is fixed at a predefined axial position on the piston tube or on an adjoining component on the vehicle body via a non-positive, material and/or positive connection, or via an adhesive or embossment connection.

4. The safety belt arrangement according to claim 3, wherein the tube element is a fastening clip, which peripherally surrounds the piston tube at a predefined axial position, and/or the tube element has a fastening tab projecting radially outwards, via which the tube element is adapted to be fastened to an adjoining component of the vehicle body.

5. The safety belt arrangement according to claim 4, wherein the fastening tab of the tube element has an elongated hole for screwing to the adjoining component of the vehicle body, and wherein the longitudinal extension of the elongated hole is aligned axially parallel to the piston tube (23).

6. The safety belt arrangement according to claim 1, wherein an inner and/or outer peripheral side of the piston tube is formed with a constant inner and outer diameter and/or in a smooth cylindrical manner over its entire tube length, and/or that the inner and/or outer peripheral side of the tube element (31) is formed with a constant inner and outer diameter and/or in a smooth cylindrical manner over its entire tube length.

7. The safety belt arrangement according to claim 1, wherein, for a progressive force level course, the tube element is positioned on the piston tube at an end of the force limiting path or, for a degressive force level course, the tube element is positioned at a beginning of the force limiting path on the piston tub, or wherein, for a wave-like force level course, the tube element is positioned on a middle section of the piston tube.

8. The safety belt arrangement according to claim 1, wherein, in a fastened state, a belt tongue of the safety belt is in detachable connection with a vehicle-side safety belt buckle, which is fastened via a cable element and via the belt force limiting unit to the vehicle body, and wherein the cable element is guided with its cable end through the piston tube and is connected to the piston.

9. The safety belt arrangement according to claim 8, wherein the cable element is guided via a vehicle body-side fitting by cable deflection, and wherein the fitting has a support contour against which in the event of the belt force being limited, the piston tube is adapted to be supported with its side facing away from the piston.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0017] FIG. 1 is a perspective view of a safety belt arrangement with a fastened safety belt, but without vehicle occupants;

[0018] FIG. 2 shows an assembly including the safety belt buckle of the safety belt arrangement and the belt force limiting unit, in isolation;

[0019] FIG. 3 is a view corresponding to FIG. 2 in a partial sectional view;

[0020] FIG. 4 is a force characteristic curve of the belt force limiting unit shown in FIG. 3;

[0021] FIGS. 5 and 6 are views according to FIGS. 3 and 4 according to an exemplary embodiment;

[0022] FIGS. 7 and 8 are views according to FIGS. 3 and 4 according to an exemplary embodiment;

[0023] FIG. 9 is a view corresponding to FIG. 2 according to an embodiment; and

[0024] FIG. 10 is a sectional view along the sectional plane A-A of FIG. 9

DETAILED DESCRIPTION

[0025] FIG. 1 shows a vehicle seat with an associated safety belt arrangement, the safety belt 1 of which is fastened, but without vehicle occupants. Consequently, in the vehicle transverse direction y, a lap belt 3 of the safety belt 1 extends between a vehicle-internal attachment point and an attachment point A outside the vehicle. The vehicle-internal attachment point A located at the height of the pelvic region is designed to be detachable, namely with a belt tongue 7 retained on the safety belt 1 and a cooperating, fixed safety belt buckle 9 into which the belt tongue 7 is inserted. At about shoulder height, there is a third vehicle-external attachment point. This is realized in current practice by a deflection fitting, not shown, which is mounted on a vehicle pillar, not shown, about which the shoulder belt 5 is guided to a belt retractor 11 installed in the vehicle pillar, in which the safety belt 1 can be wound on a winding drum. The belt retractor 11 has a blocking unit in common practice. In a safety belt 1 fastened to the vehicle occupant, in the event of an accident-related vehicle deceleration, the winding drum of the belt retractor 9 is blocked by means of the blocking unit in order to prevent the belt from pulling out. As a result, a belt force F (FIG. 1) from the safety belt 1 acts on the vehicle occupant. If the belt force F exceeds a predetermined limit value, then a belt force limiting unit 13 is activated, by means of which the belt force F exerted on the vehicle occupant can be limited to a predefined force level.

[0026] As is apparent from FIG. 2, the safety belt buckle 9 is attached via a cable 15 and via the belt force limiting unit 13 to a deflection fitting 19, which is mounted on the vehicle body 17 roughly indicated in FIG. 1. Accordingly, the cable 15 is attached at one end to the safety belt buckle 9 and is guided over the vehicle body-side deflection fitting 19 by cable deflection. In the further course, the belt force limiting unit 13 joins, realized as a piston/cylinder assembly having a piston tube 23 and a piston 25. According to FIG. 2, downstream of the deflection fitting 19, the cable 15 is guided through the piston tube 25 and connected to the piston 25, for example through embossment. In its rest position or non-use position shown, the cone-shaped piston tip 29 of the latter is in abutment with an end face of the piston tube 23 facing away from the deflection fitting 19. Therefore, the piston tube 23 is arranged in the axial direction between a cup-shaped stop element 27, which is formed on the deflection fitting 19, and the cone-like piston tip 29, which protrudes partially into the piston tube 23.

[0027] In an accident-related vehicle deceleration, the blocking unit blocks the winding drum of the belt retractor 11, preventing the belt from pulling out. If the belt force F acting on the vehicle occupant exceeds a predetermined limit, the piston 25 is displaced about a force limiting path s within the piston tube 23, while expanding and plastically deforming the latter. In this way, the belt force F exerted on the vehicle occupant is limited to a predefined force level. In this case, the maximum possible force limiting path s.sub.max corresponds to the piston tube length.

[0028] The belt force level provided by the belt force limiting unit 13 via the force limiting path s is illustrated on the basis of the force characteristic curve shown in FIG. 4. Thus, in the event of the belt force being limited in which the piston 25 is displaced beyond the maximum force limiting path s.sub.max, it progressively increases. Such a force characteristic curve is set with the aid of a tube element 31, which to form a double tube structure is pushed telescopically onto the piston tube 23 and there, is fixed in the axial direction, for example, by means of an adhesive or embossment connection. In FIGS. 2 and 3, the tube element 31 is positioned on the piston tube 23 at the end of the force limiting path s (i.e., directly at the stop element 27). Purely by way of example, the tube length I.sub.R of the tube element 31 is 10% of the tube length of the piston tube 23. Accordingly, the piston tube 23 comprises a tube section which is enclosed by the tube element 31 and a tube section which is not covered by the tube element 31.

[0029] Both on their internal and external circumference side, the piston tube 23 and the tube element 31 have a constant inner and outer diameter over their entire tube length, i.e., a consistently constant thickness of material, and are formed in a smooth cylindrical manner. In order to enable a smooth adjustment of the tube element 31 with a not-yet-implemented adhesive or embossment connection, the inner diameter of the tube element 31 is designed to be greater by a slight play than the outer diameter of the piston tube 23.

[0030] As an alternative to the above exemplary embodiment, in FIG. 5 the tube element 31 is positioned on the piston tube 23 at the beginning of the force limiting path s (i.e., directly on the piston tube end face facing the piston (25)). This creates the force characteristic curve with a degressive force level path F(s) indicated in FIG. 6, in which at the beginning of the belt force limitation, a high force level is established, which is reduced in the further force limiting path. Alternatively, the tube element 31 shown in FIG. 7 is positioned on a middle section of the piston tube 23, whereby the force characteristic curve with a wave-like force level path F (s) indicated in FIG. 8 is obtained.

[0031] As an alternative to the preceding exemplary embodiments, a fixed adhesive and/or embossment connection between the tube element 31 and the piston tube 23 is omitted in FIGS. 9 and 10. Instead, in FIGS. 9 and 10, the tube element 31 is realized as a fastening clip with a radially projecting fastening tab 33, which is fastened to the vehicle body 17 via a screw connection 35 (FIG. 10). In this way, the fastening clip 31 remains in loose or easily detachable contact with the piston tube 23 even in the assembled state. For a simple adjustment of the force characteristic curve of the belt force limiting unit 13, the screw hole 37 of the fastening tab 33 is designed as an elongated hole, notably with a longitudinal extent parallel to the axis of the piston tube.

[0032] The fastening clip 31 is made in a bending process from a strip-shaped sheet metal part, whose tube section, circular in cross section, circumferentially engages around the piston tube 23 at a predetermined axial position. In FIG. 9, the fastening tab 33 radially projecting outwards from the fastening clip 31 is spaced via a lever arm length h from an attachment point 39, at which the deflection fitting 19 is attached to the vehicle body 17.

[0033] In a load event or in the event of the belt force being limited, the assembly shown in FIG. 9, formed of the safety belt buckle 9, the deflection fitting 19 and the belt force limiting unit 13, is acted on by a torque around the point of attachment 39. In this case, the fastening clip 31 acts in a double function as an anti-rotator or torque support, which counteracts the rotation of the assembly.

[0034] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.