EP0447762A1 - Buckle for safety belt provided with a tensioning device - Google Patents

Abstract

A belt buckle for a seat belt system, which is provided with a back tensioning device, is secured by a pawl (70) against unintentional opening at the end of the back tensioning stroke. The pawl (70) locks the release button (30) on the housing before it has reached the end of its idle stroke. The pawl (70) is activated by the inertial forces acting on its center of gravity at the end of the backlash stroke with a certain lever. <IMAGE>

Description

The invention relates to a belt buckle for a seat belt system, which is provided with a back tensioning device, which is effective between the belt buckle and an anchoring point on the vehicle body or on a vehicle seat.

Belt buckles for seat belt systems are known in numerous designs. A design has proven itself in which a guideway for the tongue is formed in the housing of the belt buckle and a latch which is displaceably guided or pivotably mounted on the housing transversely to the guideway interacts with a latching opening of the tongue. A locking member which is displaceably guided in the housing parallel to the guideway holds the bolt in its locking position, as long as a trigger button which is likewise displaceably guided in the housing parallel to the guideway is in their rest position. The trigger button is coupled to the locking member to move this when actuated into a release position in which the bolt is released from the latching opening of the tongue.

The use of such a belt buckle in seat belt systems with a back tensioning device is unproblematic if the back tensioning force is effective, for example, on the belt retractor. Back tensioning devices have also been proposed which take effect between the belt buckle and its fastening point on the vehicle body or a vehicle seat. Back tensioning devices of this type shorten the distance between the fastening point of the belt buckle and the buckle itself by a few centimeters, for example 10 cm. The back tensioning devices used in such cases are mechanical and have an energy store in the form of a tensioned spring, which is released by a sensor that responds to inertial forces and, if necessary, causes back tensioning.

Mechanical back tensioning devices require a very strongly dimensioned spring to provide the required back tensioning force. The vehicle-sensitive triggering of such a spring with easily reproducible triggering thresholds presents great difficulties.

With a pyrotechnic back tensioning device, which has a piston / cylinder linear drive as back tensioning drive with a pyrotechnic gas generator acting on the piston in the cylinder in the event of triggering, high back tensioning forces can be achieved comparatively easily. It has now been found, however, that a belt buckle of the type described in the introduction tends to open automatically when used in connection with such a pyrotechnic back tensioning device.

The invention has for its object to develop a belt buckle of the type specified in that it can be used without problems in seat belt systems which are equipped with back tensioning devices which produce relatively high back tightening accelerations, and that its design, size and construction correspond to buckle constructions which are not specifically intended for this purpose.

This object is achieved with the belt buckle of the type specified in the introduction in that the release button can be locked by means of a pawl on the housing against movement in the actuating direction, that the pawl is pretensioned by pretensioning means in a position in which it does not hinder the actuation stroke of the release button that the pawl is pivotally mounted on the housing or on the release button and that the center of gravity of the pawl is offset by such a value perpendicular to the direction of displacement around the buckle during the backward movement against the pivot axis of the pawl that the pawl under the action of a predetermined threshold value Exceeding delay of the buckle in its direction of displacement is overcome by overcoming the biasing means in its engagement position, in which it locks the trigger button on the housing. In normal use, the pawl is held in its rest position by the pretensioning means, so that the release button can be operated without hindrance. During a back tightening process, the belt buckle is displaced towards its anchoring point with high acceleration. At the end of this back tightening stroke, the back tightening movement is terminated abruptly, so that high delays occur at the buckle and the functional parts contained therein. The release button now strives to perform a release stroke under the effect of its inertia. In doing so, it first carries out an idle stroke, which is provided in all common lock designs, in order to prevent the belt buckle from being opened unintentionally. Before the release button has reached the end of its idle stroke, the pawl is under the effect of the same delay Engagement position has been pivoted so that it prevents the trigger button from moving further in the actuating direction thereof. It has been shown that such a pawl can be assigned to existing buckle constructions without changing the design, size and construction. It is therefore easily possible to retrofit them into existing constructions in order to make proven buckle designs suitable for use in restraint systems with a tightening device.

Some advantageous developments of the invention are specified in the subclaims.

Fig. 1

eine schematische Perspektivansicht einer Rückstrammeinrichtung, die an einem Gurtschloß angreift;

Fig. 2

eine teils im Schnitt gezeigte Seitenansicht der Rückstrammeinrichtung;

Fig. 3

einen Längsschnitt eines erfindungsgemäßen Gurtschlosses im Zustand der betätigten Auslösetaste;

Fig. 4

eine analoge Schnittansicht des Gurtschlosses im Zustand der eingeschobenen und verriegelten Steckzunge;

Fig. 5

eine Schnittansicht des Gurtschlosses entlang Linie V-V in Fig. 4;

Fig. 6

einen Querschnitt des Gurtschlosses entlang der Linie VI-VI in Fig. 5;

Fig. 7

eine schematische Perspektivansicht der Funktionsteile des Gurtschlosses;

Fig. 8

eine Explosivansicht der Funktionsteile des Gurtschlosses; und

Fig. 9 und 10

vergrößerte Detailansichten zweier Ausführungsformen zur Erläuterung ihrer Wirkungsweise.

Further features and advantages of the invention will become apparent from the following description of several embodiments of the invention and from the drawing, to which reference is made. The drawing shows:

Fig. 1

is a schematic perspective view of a rear tightening device that engages a buckle;

Fig. 2

a partially shown in section side view of the rear tightening device;

Fig. 3

a longitudinal section of a belt buckle according to the invention in the state of the actuated trigger button;

Fig. 4

an analog sectional view of the buckle in the state of the inserted and locked tongue;

Fig. 5

a sectional view of the buckle along line VV in Fig. 4;

Fig. 6

a cross section of the buckle along the line VI-VI in Fig. 5;

Fig. 7

a schematic perspective view of the functional parts of the buckle;

Fig. 8

an exploded view of the functional parts of the buckle; and

9 and 10

enlarged detail views of two embodiments to explain their mode of operation.

The back tensioning device shown in FIG. 1 consists of a pyrotechnic piston / cylinder back tensioning drive 10, the cylinder of which is anchored to the vehicle body, a longitudinal guide for the belt buckle 12 in the form of an elongated anchoring plate 16 provided with an elongated hole 14, a traction cable 18 which holds the piston 20 connects to the fastening fitting 22 of the belt buckle, and a deflection roller 24, over which the pull rope 18 is guided and which is mounted on a fastening bolt 26, by means of which the anchoring plate 16 is fastened to the vehicle body.

Figures 1 and 2 show the back tensioning device in the non-activated state. As can be seen from FIG. 2, an end face of the Koblen 20 can be acted upon by compressed gases that are generated by a pyrotechnic gas generator 28. under the action of the compressed gases, the piston 20 is driven with extremely high acceleration and pulls the buckle 12 downward via the pull rope 18 and the fastening fitting 22. At the lower end of the elongated hole 14, the movement of the buckle 12 is suddenly braked. A backstop integrated in the piston 20 prevents the belt buckle 12 from being able to be displaced in the direction of its starting position after the back tightening has been carried out.

If the belt buckle 12 is suddenly braked at the end of the back tightening stroke, high inertia forces occur on the release button 30 and the parts connected to it, which are oriented in the direction of the release movement of the release button.

The design of the belt buckle, which is now described with reference to FIGS. 3 to 10, prevents these inertial forces from causing the belt buckle to open unintentionally.

The anchoring fitting 22 is connected to the load-bearing part of the lock housing 32 by a rivet connection. This housing 32 is surrounded by a cover in the form of a plastic shell 34. The lock housing 32 is provided with a U-shaped, raised bearing bracket in plan view, between the two parallel legs 36, 38 of which a pivot bolt 40 is mounted by means of a bearing bolt 42. The trigger button 30 has two parallel arms 30A, 30B which extend into the lock interior and which are provided at their free end with a guide slot through which the outer ends of the bearing bolt 42 pass. The trigger button 30 is slidably guided on the outer sides of the legs 36, 38.

The lock housing 32 is provided with a guide track 44 for a tongue 46 which has a latching opening 48. A control cam 50 of the pivot bolt 40 projects into the guide track 44. The pivot bolt 40 is also provided with a detent 52 in the region of its free end.

Between the two arms 30A, 30B of the release button 30, a locking member 54 in the form of a steel plate is attached above a shoulder 56 at the free end of the pivot bolt 40. A compression spring 58 is supported with one end on the locking member 54 and the other end on a lever arm 60 of the pivot bolt 40, which is opposite the control cam 50.

In the position shown in FIG. 3, the shoulder 56 of the swivel bolt 40 engages behind the front edge of the locking member 54, so that the detent 52 is pivoted out of the guideway 44 by the compression spring 58. The trigger button 30 is shown in its actuated position.

In the state shown in FIG. 4, the tongue 46 is pushed in and the locking lug 52 is locked in the locking opening 48.

In the embodiment shown in FIGS. 5 to 9, a pawl 70 is pivotally mounted on the release button 30 on a bearing pin 72, the axis of which is oriented perpendicular to the guide track 44. The pawl 70 is designed as a one-armed lever, at one end of the pawl is mounted and the other, free end of the pawl tip 74. This pawl tip 74 cooperates with a locking edge 76 at a rectangular opening 78 in the leg 38. The pawl 70 is biased by a spring 80 bent from spring wire in its rest position out of engagement with the locking edge 76. Since the pawl 70 is designed as a narrow, elongated lever which extends parallel to and in the immediate vicinity of the leg 38, it can easily be accommodated within the plastic shell 34 without changing its shape, in particular without increasing its dimensions.

The operation of the buckle will now be described with reference to FIG. 9. Fig. 9 shows the orientation of the buckle and the pawl in normal use: the longitudinal axis of the buckle, which corresponds to its direction of displacement in the back tightening case, is inclined at an angle of, for example, about 35 ° to the vertical. Due to this arrangement, the pawl 70 is subjected to a gravity component, by means of which it is biased into its normal rest position. This bias in the rest position is further supported by the spring 80 (not shown in FIG. 9 for simplification). However, designs are also possible in which the pretensioning of the pawl 70 in its rest position is achieved either solely by gravity or solely by spring pretensioning.

worin m die auf den Schwerpunkt S bezogene Masse der Sperrklinke 70 und a ein vorbestimmter Schwellwert der Verzögerung ist, bei dessen Überschreitung die Sperrklinke 70 in ihre Eingriffsstellung verschwenkt wird.If, as in the embodiment according to FIG. 9, no additional spring is used, a pawl 70 acts Gravity component G, which acts with the lever arm X at the center of gravity S of the pawl. On the other hand, the center of gravity S is offset by a dimension y relative to the pivot axis A of the pawl 70, perpendicular to the direction of displacement of the buckle in the case of back tension. As a result of this displacement, the inertia forces acting on the center of gravity S become effective in the event of an abrupt deceleration of the pawl 70 with the lever arm y in order to pivot the pawl 70 into its engagement position on the locking edge 76 of the opening 78. The engagement movement of the pawl 70 only comes about after the pretensioning force holding it in its rest position has been overcome. The following relationship applies:

$\text{x · G <m · a · y}$

where m is the mass of the pawl 70 relative to the center of gravity S and a is a predetermined threshold value of the deceleration, beyond which the pawl 70 is pivoted into its engagement position.

As can be seen from Fig. 9, the pawl tip 74 is in its rest position at a distance d from the locking edge 76. This distance d is dimensioned sufficiently large so that the pawl 70 has safely entered the opening 78 before the height of the Locking edge 76 reached. On the other hand, this distance d is significantly smaller than the idle stroke L, also shown in FIG. 9, of the release button 30, which ensures that the release button 30 is locked before the end of the idle stroke L is reached.

When dimensioning the dimension y, taking into account the mass of the pawl 70, care must be taken to ensure that the forces which bring the pawl into its engagement position are sufficiently large to very quickly insert the pawl into the opening 78. For the same reason, the predetermined threshold for the delay a, ab which the prestressing force is overcome is chosen to be relatively small. A value of approximately -5 g is a suitable value, on the one hand to counteract only slightly the forces causing the control of the pawl 70, but on the other hand to ensure that the pawl remains safely in its rest position in the normal operating state. The strength of the spring 80 can be calculated according to the same criteria if it is to produce the preload alone or in cooperation with gravity.

In the embodiment of FIG. 10, the pawl 70 is pivotally mounted on the housing. With its pawl tip 74, it can be moved into the movement path of a rib 30a of the release button 30. Due to the gravity component acting on its center of gravity S with the lever arm X, the pawl 70 is held in its normal rest position, in which it does not hinder the release stroke of the key 30. In the back tension case, at the end of the back tension stroke, due to the high delays then occurring at the center of gravity S, an inertial force acts with the lever arm y, which causes the pawl 70 to pivot counterclockwise into the engaged position thereof. The same considerations apply to the dimensioning of the distance d and the dimensions y and X as for the embodiment according to FIG. 9.

Claims (8)

Seat belt buckle for a seat belt system which is provided with a back tensioning device which acts between the seat belt buckle and an anchoring point on the vehicle body or a vehicle seat by displacing the seat belt buckle towards the anchoring point, with the following features: - A guideway for the tongue is formed in the housing of the buckle; - A latch mounted on the housing interacts with a locking opening of the tongue; - A trigger button, which is displaceable parallel to the guideway in the housing, is provided to release the bolt for releasing it from the latching opening of the tongue and secured with an idle stroke to secure it against unintentional triggering;

characterized in that

the release button (30) can be locked against movement in the actuating direction by means of a pawl (70) on the housing, that the pawl (70) is pretensioned by pretensioning means (G, 80) in a position in which it actuates the actuation stroke of the release button (30) does not hinder that the pawl (70) on the housing or on the trigger button (30) is pivotally mounted and that the center of gravity (S) of the pawl (70) by such a dimension (y) perpendicular to the direction of displacement of the buckle opposite the back tightening movement the pivot axis (A) of the pawl (70) is offset such that the pawl is displaced into its engagement position under the effect of a deceleration of the buckle in its displacement direction exceeding a predetermined threshold value (a) while overcoming the pretensioning means (G, 80), in which it locks the release button (30) on the housing. Belt buckle according to claim 1, characterized in that the pretensioning means (G) are at least partially formed by the force of gravity acting on the pawl. Belt buckle according to claim 1 or 2, characterized in that the biasing means are at least partially formed by a spring (80). Belt buckle according to one of the preceding claims, characterized in that the pawl (70) is mounted on the release button (30) and interacts with a latching edge (76) on the housing which, when the release button (30) is not actuated, in the direction of displacement of the buckle at a distance from the Pawl tip (74) of the pawl (70) is located. Belt buckle according to one of claims 1 to 3, characterized in that the pawl (70) is mounted on the housing and with its pawl tip (74) in the path of movement a part (30a) of the release button (30) which can be moved into it in a blocking manner and that this part (30a) is located at a distance from the latch tip (74) when the release button (30) is not actuated. Belt buckle according to one of the preceding claims, characterized in that the pawl (70) forms a one-armed lever which extends generally parallel to the direction of displacement of the belt buckle. Belt buckle according to one of the preceding claims, characterized in that the predetermined threshold value (a) of the deceleration and the idle stroke (L) of the release button (30) are coordinated with one another in such a way that the pawl (70) under the effect of the deceleration occurring at the end of the back tensioning path is shifted into its engaged position before the release button (30) has reached the end of its idle stroke (L) under the effect of the same delay and because of its inertia. Belt buckle according to claim 7, characterized in that the predetermined threshold value (a) is approximately -5 g.

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