WO2014154671A1

WO2014154671A1 - Seatbelt retractor with a force limiting device

Info

Publication number: WO2014154671A1
Application number: PCT/EP2014/055930
Authority: WO
Inventors: Klaus-Peter Singer; Ronald Jabusch
Original assignee: Autoliv Development Ab
Priority date: 2013-03-28
Filing date: 2014-03-25
Publication date: 2014-10-02
Also published as: DE102013205690A1; DE102013205690B4

Abstract

The present invention relates to a seatbelt retractor with a force limiting device (7), having a two-part belt shaft (1) mounted rotatably about an axis of rotation in the legs (4, 5) of a U-shaped frame (2), said belt shaft having a first part (9), on which a seatbelt can be wound, and a second part (10), which can be locked fixedly in relation to the vehicle against at least one of the legs (4, 5) of the frame (2) by means of a vehicle-sensitive and/or belt-sensitive controllable blocking device (8), and further having the force limiting device (7), which enables a force-limited relative movement between the first part (9) and the second part (10) upon activation, wherein the first and second parts (9, 10) of the belt shaft (1) overlap one another axially in a section between the legs (4, 5) of the frame (2), forming an annular space (11), and the force limiting device (7) is formed by a strip element (12, 13).

Description

Belt retractor with a force limiting device

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

A belt retractor of the generic type is known for example from WO 96/32303. The belt retractor described there has a two-part belt shaft with a arranged between the parts of the belt shaft torsion bar. On one of the parts of the belt shaft, the belt shaft body, a seat belt is wound up, while the other part of the belt shaft, also called profile head, is blocked in a vehicle-sensitive or belt-sensitive control of a blocking device vehicle-fixed. In the event that the belt pull-out force exceeds a predetermined belt pull-out force with a blocked second part of the belt shaft, the belt shaft body can rotate by a plastic deformation of the torsion bar about its longitudinal axis in Gurtauszugsrichtung. The thereby to be overcome predetermined belt withdrawal force is determined by the plastic deformation limit of the torsion bar.

DE 201 10 423 U1 also discloses a belt retractor in which a force limiting device formed by a metal band is provided, which is pulled through a chicane during the force - limited belt webbing extension. The advantage of this solution is that the belt extension length, during which acts the second force limiting device, can be considerably extended by the use of a correspondingly long metal strip, the destroyed energy and the The resulting force limiting level during the passage of the metal strip through the chicane is almost constant. The chicane itself is realized by an insert, which is mounted on one of the parts of the belt shaft, while the metal strip is held tensile strength on the other part of the belt shaft.

The object of the invention is to provide a belt retractor with a force limiting device, which should be as simple as possible. Furthermore, the occupant should still be securely restrained by the safety belt even after activation of the force limiting device in the event of a second impact.

To solve the problem, a belt retractor with the features of claim 1 is proposed. Further preferred embodiments of the invention can be found in the subclaims.

According to the basic idea of the invention, it is proposed that the first and the second part of the belt shaft overlap axially in a section between the legs of the frame of the belt retractor to form an annular space, and

the force-limiting device is formed by a band element which rests with a first section on the radially outer wall of the annular space and with a second section on the radially inner wall of the annular space and is deflected between the first and the second section in a deflection point, in which

the band element in a relative movement between the first and the second part by a rotation of the deflection energy-consuming from the outer wall on the inner wall or vice versa ab- or wound, wherein -an at least one end of the band member a stop for producing a positive connection between the band member and a part of the belt shaft is provided.

The proposed belt retractor has several advantages over the solutions known in the prior art. The belt retractor is inexpensive and easy to assemble, since the force limiting device is formed solely by the deflected band element. Other previously required components, such as e.g. a chicane, are not required. Furthermore, the energy destruction takes place solely by the rotation of the deflection point, in which the band element is deformed energy-consuming by a continuous bend. Furthermore, the duration of the effect of the force limiting device can be extended by the choice of a correspondingly long band element. By provided on the band element stop the rotational movement of the first part of the belt shaft relative to the second part can be limited, so that the two parts of the belt shaft then on the created by the stop positive connection in the direction of rotation of the first part of the belt shaft up to a certain Gurtauszugskraft rotatably connected to each other. As a result, the occupant is restrained by the seat belt during a second impact following the first impact after the force-limited belt pullout.

In this case, the stop can be made particularly inexpensive by being formed by an embossed out of the surface of the band member nose. Through the nose an outwardly projecting projection is formed, with which the end of the band element rests against a corresponding mating surface on one of the parts of the belt shaft or during kraftbegrenz - th belt extraction movement comes to the plant.

It is also proposed that a recess with a shape corresponding to the shape of the stop is provided on one of the parts of the belt shaft, in which the band element is fixed in a form-fitting manner with the stop or comes to rest during the force-limited relative movement. Through the recess with the corresponding shape of the end of the band member is particularly high tensile strength fixed to the part of the belt shaft, the band element can be fixed to the stop already at the beginning of the force-limited relative movement in the recess or only during the force-limited relative movement with the stop in the recess can engage and thereby prevent subsequent rotational movement.

It is further proposed that the distance between the outer wall and the inner wall of the annular space decreases or increases at least in sections in the direction of the rotational movement of the first part during the activation of the second force limiting device. The principle of the proposed force limiting device is based, as already described above, that the deflection point of the band element rotates energy-consuming. The measure of the destroyed energy is dependent on the radius of the deflection point with the principle that the smaller the radius, the greater the destroyed energy. Due to the proposed increasing or decreasing distance, the radius of the deflection point can be changed during the force-limited relative movement, so that degressive and progressive force limiting profiles can be realized. At a decreasing distance, the radius of the deflection becomes smaller, so that the force limiting level increases. With an increasing distance then follows lent a decreasing force limit level.

It is also proposed that the radially outer end of the band element is fixed by means of a clamping ring on one of the two parts of the belt shaft. By the clamping ring, the end of the band member can be additionally fixed, wherein the proposed recess can be provided in this case also in the clamping ring.

According to a further preferred embodiment of the invention, it is proposed in this case that the outer end of the band element is guided and deflected radially outwardly through a recess in one of the parts of the belt shaft, and the clamping ring, the radially outwardly deflected end of the band element to the outside covers. Due to the deflection of the band member, the end is additionally held by an increased frictional engagement on the part of the belt shaft, wherein the required tensile force for extending the end by the created deflection and the band member outwardly covering clamping ring is further increased. In addition, the clamping ring covers the outwardly deflected end of the band member to the outside, so that the wound webbing does not come to rest at the deflected end of the band element and during the winding and unwinding is not damaged at the edge of the band element.

It is also proposed that the two parts of the belt shaft are connected to each other via the clamping ring in the axial direction. Through the connection created ensures that the two parts of the belt shaft are connected to each other during the force-limited relative movement in the axial direction, which in turn positive for the rotational movement and the Storage of the rotating part of the belt shaft is.

According to a further advantageous embodiment of the invention, it is proposed that two identical band elements are provided, which are arranged point-symmetrical to the axis of rotation of the first part of the belt shaft. The proposed solution, the resulting radial forces can be reduced, since they compensate for each other by the symmetrical arrangement of the two band members in the ideal case. Furthermore, the band elements can be made cheaper due to the larger number of parts to be produced.

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

1: a belt retractor according to the invention with a

Force limiting device in side view and in sectional view, and

Fig. 2: a two-part belt shaft of the belt retractor with the

Force limiting device in exploded view, and

Fig. 3: the force limiting device on different parts of the belt shaft, and

4 is a sectional view of the force limiting device before and after activation, and

5 shows a possible course of the force limiting level over the belt extension length. 1 shows a belt retractor with a two-part, in the legs 4 and 5 of a frame 2 rotatably mounted belt shaft 1 can be seen. On the leg 5, a pyrotechnic tightening device 3 is provided which drives the belt shaft 1 in an early phase of the accident before the beginning of the forward displacement of the occupants abruptly in the winding and possibly pulls out in the seat belt belt slack.

In the figure 2, the two-part belt shaft 1 with a first part 9 and a second part 10 can be seen in exploded view. The first part 9 is in this case a Gurtwel- llenkörper on which a safety belt is wound, and the second part 10 is a profile head, which is a carrier of a blocking device 8 in the form of a blocking pawl. When exceeding predetermined acceleration values of the vehicle or the Gurtbandauszuges the blocking device 8 is driven, i. the blocking pawl engages in a toothing on the leg 4 of the frame 2 and blocks the second part 10 fixed to the vehicle against the direction of belt withdrawal. Further, a force limiting device 7 can be seen, which, as will be described below, also between the two parts 9 and 10 of the belt shaft 1 is arranged. At the same time, the two parts 9 and 10 of the belt shaft 1 are connected to each other via a clamping ring 6 so that they are in normal use, ie before the activation of

Force limiting device 7, are to be regarded as a solid composite. The force limiting device 7 is formed by two band elements 12 and 13, which at their ends respectively have stops 26, 27, 28, 29 which are formed by noses embossed out of the surface of the band elements 12 and 13. As can be seen in FIG. 1, the first part 9 and the second part 10 of the belt shaft 1 overlap to form an annular space 11 in which the band elements 12 and 13 are arranged. The band elements 12 and 13 are, as can be seen in Figure 3, for mounting either with the radially outer ends in the second part 10 of the belt shaft 1 or with the radially inner ends in corresponding recesses 24 and 25 on the first part 9 of the Gurtwelle 1 inserted and then fixed by placing the respective other part 9 or 10 with the other ends of this.

In the right-hand illustration of FIG. 4, the belt retractor can be seen after installation in the cutting direction BB of FIG. 1 with the force-limiting device 7 before activation. The band elements 12 and 13 are arranged identically and point-symmetrically diametrically to the axis of rotation of the belt shaft 1. The band members 12 and 13 have at their ends to the stops 26,27,28,29, with which they engage positively in the pulling direction in corresponding recesses 16, 17,24,25, which in relation to the shape of the ends of the band members 12 and 13 have a negative shape. The stops 26,27,28,29 are formed by shaped from the surface of the band members 12 and 13 out-shaped nose-shaped, which are highlighted against the pulling direction and thereby each form a stop surface with which the band members 12 and 13 at a applied traction on the first and the second part 9 and 10 of the belt shaft 1 support. The recesses 16 and 17 are not arranged directly on the second part 10 of the belt shaft 1, but instead at least half formed on the clamping ring 6, which holds the two parts 9 and 10 of the belt shaft 1 in the axial direction to form a composite. The band members 12 and 13 are with their radially outer ends 31 and 32 through recesses 30 and 33 in the second part 10 of Gurtwelle 1 outwardly guided and deflected, so that the ends 31 and 32 abut the outer edge surface of the second part 10. The ends 31 and 32 are covered by the clamping ring 6 to the outside, so that the wound on the belt shaft 1 seat belt when winding and unwinding does not travel over the ends 31 and 32 and is thus protected from increased abrasion. Furthermore, this will of course also the ends

31 and 32 protected against mechanical forces. In addition, the clamping ring 6 exerts a clamping force on the ends 31 and

32 of the band members 12 and 13, so that the band members 12 and 13 do not slide with acting tensile forces through the recesses 30 and 31 in the annular space 11. The holding force of the radially outer ends 31 and 32 results from the sum of the clamping force of the clamping ring 6, the frictional force in the deflection of the recesses 30 and 33 and the positive connection by the engaging in the recesses 16 and 17 stops 26 and 27th

In the right-hand illustration of FIG. 4, the force-limiting device 7 can be seen before activation. The force-limiting device 7 is activated by the second part 10 of the belt shaft 1 is blocked in a first step by the blocking device 8 fixed to the vehicle, and by the first part 9 of the belt shaft 1 then begins in a second step by exceeding a by the force limiting Device 7 defined Gurtauszugskraft opposite the second part 10 to rotate in the direction of arrow P. Due to the force-limited relative movement, the band members 12 and 13 to the deflection points 22 and 23, whereby the band members 12 and 13 of the radially outer wall 18 of the second part 10 of the belt shaft 1 on the radially inner wall 19 of the first part 9 of Belt shaft 1 are processed. In this case, the band elements 12 and 13 in the deflection points 22 and 23rd deflected energy consuming until the left-hand representation to be recognized position is reached, in which the further rotational movement is prevented by the tensile strength of the band members 12 and 13 on the stops 26,27,28,29. By unwinding of the band members 12 and 13 which abuts before activation on the inner wall 18 portions 20 and 21 are completely wound on the inner wall 19 of the first part 9 of the belt shaft 1, so that the band members 12 and 13 to be deflected directly without , Run from the inner wall 19 to the recesses 30 and 33 and form a tensile connection of the parts 9 and 10 of the belt shaft 1. The connection of the band members 12 and 13 to the parts 9 and 10 of the belt shaft 1 and the mechanical strength of the band members 12 and 13 are selected so that a tensile force of at least 15 kN can be transmitted.

The annular space 11 is formed in the direction of arrow P in the two sections, which are traversed during the rotational movement of the part 9 of the turning points 22 and 23, continuously widening, i. the distance between the inner and outer walls 19 and 18 increases continuously. As a result, the radii of the deflecting parts 22 and 23 continuously increase during the circulating movement, which in turn reduces the energy dissipated in the deflecting points 22 and 23 and decreases the force limiting level.

FIG. 5 shows the course of the force limiting level above the belt extension length. The force limiting level initially increases steeply until both band elements 12 and 13 begin to rotate around the deflection points 22 and 23 and are deformed in the deflection points 22 and 23. Due to the increasing distances of the walls 18 and 19 and the deflection radii thereby becoming larger, the force limiting level drops subsequently continuously until the position in the left-hand illustration of FIG. 4 has been reached, ie until the deflecting parts 22 and 23 have completely circulated and the band elements 12 and 13 are completely wound up on the inner wall 19 of the first part 9 of the belt shaft 1. The band elements 12 and

13 form after unwinding a tensile connection of the two parts 9 and 10 to a tensile force of at least 15 kN, so that the occupant is retained in a second impact after activation of the force limiting device 7 through the seat belt.

Claims

Claims :

1. Belt retractor with a force limiting device (7) with -einer in the legs (4,5) of a U-shaped frame (2) about a rotation axis rotatably mounted two-piece belt shaft (1) having a first part (9) on the a webbing is wound, and a second part (10) which by means of a vehicle sensitive and / or webbing sensitive controllable blocking device (8) opposite at least one of the legs (4,5) of the frame (2) is fixed to the vehicle, and

the Kraftbegrenzungseinrichtung (7), which on activation enables a force-limited relative movement between the first part (9) and the second part (10), characterized in that

the first and second parts (9, 10) of the belt shaft

(I) axially overlapping in a portion between the legs (4, 5) of the frame (2) to form an annular space (11), and

the force-limiting device (7) is formed by a band element (12, 13), which has a first section (20, 21) on a radially outer wall (18) of the annular space

(II) and with a second portion (14, 15) against the radially inner wall (19) of the annular space (11) and between the first and the second portion (20, 21, 14, 15) in a deflection point (22, 23) is deflected, and

the band element (12, 13) during a relative movement between the first and the second part (9, 10) by circulating the deflection point (22, 23) energy-consuming from the outer wall (18) on the inner wall (19) or vice versa can be wound or wound up, and

at least one end of the band element (12, 13) has a stop (26, 27, 28, 29) for producing a positive fit Connection between the band member (12, 13) and a part (9, 10) of the belt shaft (1) is provided.

2. Belt retractor according to claim 1, characterized in that the stop (26, 27, 28, 29) is formed by a nose stamped out of the surface of the band element (12, 13).

3. Belt retractor according to one of the preceding claims, characterized in that

on one of the parts (9, 10) of the belt shaft (1) has a recess (16, 17, 24, 25) with one to the shape of the stop

(26,27,28,29) corresponding shaping is provided, in which the band member (12, 13) with the stop

(26,27, 28,29) is positively fixed or passes during the force-limited relative movement form fit to the plant.

4. Belt retractor according to one of the preceding claims, characterized in that

the distance between the outer wall (18) and the inner wall (19) of the annular space (11) decreases or increases at least in sections in the direction of the rotational movement of the first part (9) during activation of the force limiting device (7).

5. Belt retractor according to one of the preceding claims, characterized in that

the radially outer end (31, 32) of the band element (12, 13) by means of a clamping ring (6) on one of the two parts (9, 10) of the belt shaft (1) is fixed.

6. The belt retractor according to claim 5, characterized in that -the outer end (31, 32) of the band element (12, 13) a recess (30, 33) is guided and deflected radially outwards in one of the parts (9, 10) of the belt shaft (1), and the clamping ring (6) has the radially outwardly deflected end (31, 32) of the belt element (FIG. 12, 13) to the outside covers.

7. Belt retractor according to one of claims 5 or 6, characterized in that

- The two parts (9,10) of the belt shaft (1) via the clamping ring (6) are connected to each other in the axial direction.

8. Belt retractor according to one of the preceding claims, characterized in that

two identical band elements (12, 13) are provided, which are arranged point-symmetrical to the axis of rotation of the first part (9) of the belt shaft (1).