WO1989004617A1

WO1989004617A1 - Locking device in safety belts for a tongue adapted to be mounted on a strap of the safety belt

Info

Publication number: WO1989004617A1
Application number: PCT/SE1988/000623
Authority: WO
Inventors: Lennart Haglund
Original assignee: Autoliv Development Aktiebolag
Priority date: 1987-11-17
Filing date: 1988-11-17
Publication date: 1989-06-01
Also published as: SE460009B; AU2784689A; SE8704511L; SE8704511D0

Abstract

A locking device in safety belts for a tongue comprises a locking member (10) adapted to be rotated around an axis (b) between a release position and a locking position. The locking device also comprises a latch member (29) for the locking member and a movable operating member (30) to release the tongue. The locking member (10) has a contact surface for the tongue (19), the perpendicular (N) of which in the locking position of the locking member passes through a torque axis (A) which is parallel with the axis of rotation (B) of the locking member and which is so positioned that a force on the tongue (19) in the direction (U) of withdrawal of the tongue causes a resultant torque (M) on the locking member towards the release position of the locking member, so that it is easier to release the tongue when the safety belt is loaded. The axis of rotation (B) of the locking member is positioned outside the contact surface of the locking member, as seen in the direction (U) of withdrawal of the tongue. The locking member may be mounted on a resilient lug (27) yielding when the safety belt is very heavily loaded, as for example in a collision, so that the locking member then is self-locking.

Description

Locking device in safety belts for a tongue adapted to be mounted on a strap of the safety belt

Technical Field

The present invention relates to a locking device in safety belts for a tongue adapted to be mounted on a strap of the safety belt. The locking device comprises a locking member adapted to be rotated around an axis between a release position, in which the locking member does not engage the tongue, and a locking position, in which the locking member engages and retains the tongue. The locking device further comprises a latch member adapted to block the locking member in the locking position, and a movable operating member adapted to release the tongue when operated, so that the safety belt, can be unfastened. The locking device is intended for use in safety belts for vehicles, particularly motor cars. Background Art

It is previously known, for example through the Swedish patent publication 447 331, to provide locking devices for a tongue in vehicle safety belts with a locking member to retain the* tongue and a latch member blocking the locking member in the locking position. Such a latch member increase:., the reliability of the locking device, because th" risk of displacement of the locking member from the locking position, for example in a collision, is eliminated or at least substantially reduced. It is also previously known, for example through the Swedish patent publication 451 231, to arrange the latch member in such a way that it is not subjected to any substantial force even if the safety belt is heavily loaded, so that an easy and reliable removal of the latch member is possible also when the tongue is heavily loaded in the direction of withdrawal.

However, even if the latch member is easy to remove, it can sometimes be difficult to unfasten the safety belt. If the saf . ■ y belt is heavily loaded and, consequently, the tongue i:; πubjected to a heavy force in the direction of withdraw,^**! , I he tongue may squeeze the locking member, s Fig. 5 is a side view of the device shown in Fig. 3 with the axis of rotation of the locking member displaced. Best Mode for Carrying Out the Invention

The locking member 10 shown in Fig. 1 is mounted in a U-shaped support which forms the entrance path for the tongue and the sides of which form bearing means for the ends of the locking member. Each support side is provided with an aperture into which one end of the locking member penetrates. Only one side 11 of the U-shaped support with its bearing aperture 12 is shown in the figure, but the other side is designed in a corresponding way. The side 11 is provided with a lug 13 which projects into the aperture 12 and which is provided with a bearing edge 14 for the locking member 10, as will be explained more in detail below. Furthermore, three supporting means 9 for the tongue are indicated schematically.

In the illustrated embodiment, the locking member 10 has substantially U-shape with twc side portions 15,16 on the upper side and a downwards projecting bearing portion 17 on the lower side. The side portions 15,16 run along the full length of the locking member, but the bearing portion 17 only exists a ^* p ends of the locking member. The side portion 15 is designed with a substanti lly cylindrical peripheral surface l^c forming a contact surface for the tongue 1?. Th**³ side portion 16 is also designed with a substantially cylindrical peripheral surface 20. The cylindrical peripheral surfaces 18,20 have substantially equal radii and the same centre axis A spaced from the axis of rotation B for the locking member and in parallel with said axis. Adjacent the side portions 15,16 of the locking member the aperture 12 has substantially arc-shaped edges with slightly larger radii than the side portions 15,16, so that a certain play exists between t e peripheral surfaces 18,20 of the side portions 15,16 ar_J the adjacent c iges of the aperture 12. The downwards projecting bearing portion 1^" cf the locking member 10 forms a pocket 21 into which the bearing edge 14 ; .^' the iup _ _- "ar* project, se tha⁺ the locking the locking member a*"*d which is spaced from the axis of rotation of the locking member, a force on the tongue in the direction of withdrawal of the tongue can give a resultant torque on the locking member towards the release position of the locking member. With a convenient position of the torque axis of the locking member in relation to the axis of rotation of the locking member a desired resultant torque on the locking member can be obtained for different safety belt loads. After removal of the latch member, the locking member can easily be rotated to the release position by means of the operating member to release the tongue, even if the tongue is heavily loaded in the direction of withdrawal. The torque can be chosen so big that it prevails over the fractional forces appearing where the tongue abuts against the locking member, and possibly also over the forces appearing at the other contact surfaces of the locking member when absorbing the force from the tongue acting on the locking member. Thus, if desirable, the locking member can be made self opening , i. e. the locking member can be opened without any force transfer from the operating member to the locking member, as soon as the latch member hns been removed. This will facilitate the design of the operating member and, consequently, of the whole locking device . Brief Des^cription of Drawings

Three embodiments of the locking device according to the invention will now be further described below with reference to the accompanying drawings.

Fig. 1 is a schematical view, partly in section, of a buckle having a rotatably mounted locking member with a fixed axis of rotation and a tongue retained by the locking member.

Fig. 2 is a schematical view of a movably mounted locking member and a tongue retained by the locking member. Fig. 3 is a schematical side view of a locking member with a movable axis of rotation, a latch member, an operating member and a tongue retained by the locking member.

Fig. 4 is a plar, view of th***¹ device shown in Fig. 3 . that the locking member cannot be moved to the release position by means of the operating member to release the tongue. This may occur, if the vehicle after an accident is upside down and a person is hanging in the safety belt. In such a case it may be necessary to lift the person, before the operating member can be operated to unfasten the safety belt. Normally, the cooperation of several persons is necessary for carrying out this work and the operation may be time consuming, due to the difficult working conditions when an accident has occurred. The alternative is to cut off the safety belt, but this operation requires a convenient tool which not always is at hand. Furthermore, the person embraced by the safety belt must also quickly be released and removed from the vehicle, as the risk of fire is considerable in an accident of this type. Thus, it is highly desirable that the safety belt can be unfastened in a normal way, even with a person hanging in the safety belt. This would also make it much easier for a person, who is not unconscious, to release himself from the safety belt and get out of the vehicle. According to both the mentioned publications, the locking member is mounted inside the contact surface for the tongue, a:-, seen in the direction of withdrawal of the tongue. This necessitates a hook-shaped locking member that canno* stand heavy tractive forces without further balancing. Such balancing further impedes the opening of the locking device. Disclosure of Invention

The main object of the invention is therefore to provide a locking device for the tongue in safety belts, which makes it possible to reliably unfasten the seat belt even when the safety belt is heavily loaded and, consequently, the tongue is subjected to a heavy force in the direction of withdrawal . This object is achieved by giving the locking device the features set forth in the claims.

Due to the fact that the locking member has a contact surface for the tongue, the perpendicular of which in the locking position of the locking member passes through a torque axis, which is parallel with the axis of rotation of member is rc atably mounted on the lug 13. The bearing portion 17 nas a curved contact surface wi h a certain radius and a centre of curvature B which thus forms an axis of rotation for the locking member. The bottom of the pocket 21 has a radius of curvature corresponding to the curvature of the contact surface of the bearing portion, so that the locking member can rotate on the bearing edge 14 with a friction as small as possible. The locking member can be rotated between a locking position, which is shown in the figure and in which the tongue is retained by the locking member, and a release position, in which the locking member abuts against the top surface 22 of the lug and in which the tongue 19 is not retained by the locking member. The aperture 12 in the side 11 is so dimensioned that the locking member can rotate on the bearing edge with a certain play to the edges of the aperture but cannot slip off the bearing edge. During the rotational movement the locking member rotates about its bearing axis B.

As shown in Fig. 1 the centre A of the tongue contact surface 18 of the locking member is displaced from the centre B of the bearing surface provided on the lug 13 and is positioned a+ a distance a above the centre B. The force exerted by Itie tongue 19 on the locking member 10, when th<"* safety bel is loaded, so that" the tongue is actuated by β force in the direction U of withdrawal, acts on the cylindrical contact surface 18 of the locking member and can be divided into two components, one of which being directed radially along the perpendicular N through the centre A of the contact surface and the other being directed tangential ]y along the contact surface*. Duo to the position of the centre A above the centre B the radial force will cause a torque tending to turn the locking member counter-clockwise from the indicated locking position towards the release position . If the tongue abut:- against the locking member below the centre A, the tangential force will be directed downwards, and if the tongue abuts against the locking member abcve the centre A, th*^~* tangential force will be directed upwards. Thus, the tangential force can counteract or cooperate with the torque caused by the radial force, depending on the vertical position of the tongue. It is desirable to cause a torque on the locking member directed from the locking position towards the release position, i. e. in the direction indicated by the arrow M in the figure, and therefore the tongue should abut against the locking member on a level with or above the centre A, so that the tangential force not substantially counteracts the desired torque on the locking member directed against the release position of the locking member. If the position of the centre A is conveniently chosen, a desired torque on the locking member can be obtained, as the torque depends upon the distance between the centre A and the centre B and the force component at centre A perpendicular to the line connecting centre A with centre B. Thus, the line running through the centre A in parallel with the axis of rotation B of the locking member can be regarded as a torque axis for the locking member.

In Fig. 1 the centre A is shown in a vertical plane somewhat displaced from the centre B and in the locking member. However, the centre A can be positioned in or at th*= side of the vertical plane through the centre B and in or outside Ihe locking member.

By choosing the positions of the centres A and B a suitable torque in the release direction of the locking member can be obtained. This torque can be changed within wide limits from a low value close to 0 to a very large value, particularly if the tangential force on the locking member cooperates with the torque caused by the radial force. If the distance between the centres A and B is small, a small torque is obtained. Then, only some help from the load on the tongue is obtained for rotating the locking member to the release position, and the major portion of the opening force must still be transferred from the operating member. By choosing a larger distance in a convenient direction between the centres A and B the frictional force at the contact surface between the tongue and the locking member can be completely or partly compensated, and by an even larger distance the locking member can be made self-opening, so that no action from the operating member is required to rotate the locking member to the release position, when the latch member has been removed.

Figure 2 shows a slightly modified embodiment of the device shown in Fig. 1. In this embodiment, the locking member 23 is mounted on a slanting, plane surface 24 and will therfore be somewhat displaced on this surface, when the tongue 19 is loaded in the direction U of withdrawal. In this case, the axis of rotation of the locking member 23 will be formed by the top edge B of the plane surface, and when the tongue is loaded the cylindrical surface 26 of the locking member will be brought into contact with the edge of the aperture 12 which edge thus will act as a load carrying surface. Therefore, the edge of the aperture 12 and the cylindrical surface 26 should be so designed that a large contact surface is obtained, as shown in Fig. 2. This can easily be achieved, if the rvlindrical surface 26 has a centre axis C displaced from the centre axis A of the cylindrical surface 25.

Figures 3 and 4 also show an embodiment slightly modi fied with respect to the embodiment shown in Fig. 1. Th" lug 27 projecting into the aperture 12 is so arranged and designed that it yields when the locking member is heavily loaded in the direction U of withdrawal, e. g. in a collision. The cylindrical perpheral surface 20 on the side portion 16 of the locking member 10 will then engage with the edge of the aperture 12. Preferably, this edge has a curvature corresponding to the curvature of the side portion 16. It is particularly convenient that the edge of the aperture has a radius oL^' curvature which is substantially as long as the radius of curvature of the side portion 16, but has an other centre D. Th" side portion 16 can then have its centre in an axis through the centre A. By this feature is achieved that the locking member normally, i. e. when the locking member ha:: r. ^~ he*-*, exposed o a load cf the size appearing for example in a collision, will turn with a very low friction around the bearing edge 28 of the lug 27 but in case of a very heavy load is forced into contact with an edge in the aperture, so that said edge will carry the load appearing on the locking member. This case is shown in Fig. 5. In Fig. 3 also a latch member 29 for the locking member 10 and an operating member 30 to release the tongue have been indicated schematically. The latch member 29 is connected with the locking member 10 and, consequently, moves together with the locking member. The latch member is furthermore spring operated in the locking direction of the locking member, i. e. clockwise in the figure. The operating member 30 is provided with a contact surface 31 for the latch member, so that the latch member cannot be turned in the opening direction of the locking member, as long as the operating member is in the locking position, as shown in the figure. When the operating member is brought to the opening position (not shown), the contact surface 31 for the latch member 29 is moved, so that the latch member and consequently also the locking member can be turned in the opening direction nf the locking member. The latch member and the locking member are turned by the operating member by means cf a control surface (not shown) on the operating member.

If the centres A and B are conveniently positioned, a suitable torque can be obtained also in the embodiments shown in Figs. 2 and 3. However, in order to make the locking member self-opening or rotatable with only a small force over the operating member it is necessary that the resultant torque caused by the tongue on the locking member completely or almost completely balances the frictional forces at all friction surfaces of the locking member.

A special advantage can be achieved in the embodiment according to Fig. 3. If the yielding lug is so designed that it only yields for tra ^*lent forces and loads appearing in accidents, e. g. collisions, and then rebounds, when thes^ forces and loads have ceased, it is possible to achieve that the locking member is self-opening at normal or slightly higher loads. It is then possible to easily unfasten the safety belt by means of the operating member, even if the vehicle after a collision is upside down and a person hangs in the safety belt. The load from a person hanging in the safety belt is not at all as high as the load arising in a collision. The frictional force arising when the locking member is moved into contact with a force carrying surface, e. g. as shown in Fig. 5, possibly in combination with a torque acting in the locking direction of the locking member, can then balance the torque caused by the tongue, so that the locking member reliably is kept in the locking position, even if the latch member for one reason or another will not be able to perform its blocking function.

If the axis of rotation of the locking member is positioned outside of the contact surface for the tongue on the locking member, as seen in the direction of withdrawal of the tongue, there is no need to make the locking member hook- shaped and the locking member can therefore easier stand the appearing loads. This makes the design easier and facilitates the opening of the locking device.

Whilst only three embodiments of the locking device according to the invention have been shown and described, it is obvious Di l many embodiments and modifications are possible within the scope of the invention. For example, the locking means may be designed in many ways and the cylindrical surfaces may have the same or different radii and the same or different centres. The contact surface for the tongue does not need to be cylindrical but can have any shape, e. g. plane, provided that the perpendicular or perpendiculars of the surface passes at the side of the axis of rotation of the locking member, so that a torque towards the release position of the locking member acts on the locking member, when the tongue is loaded. Furthermore, the locking member may be mounted on a bearing edge designed or positioned in another way than shown and possibly be mounted on a shaft which may be resilient or have sufficien⁺ strength r-^*- take up the arising, loads. The locking member may also be arranged in such a way that it has to be rotated In the opposite direction, i. e. clockwise, to reach its release position. The torque axis will then be positioned below the axis of rotation of the locking member.

Claims

Cl aims

1. Locking device in safety belts for a tongue adapted to be mounted on a strap of the safety belt, comprising a locking member (10; 23) adapted to be rotated around an axis (B) between a release position, in which the locking member does not engage the tongue (19), and a locking position, in which the locking member engages and retains the tongue; a latch member (29) adapted to block the locking member in the locking position; and a movable operating member (30) adapted to release the tongue when operated, so that the safety belt can be unfastened, characterized in that the locking member (10*,23) has a contact surface (18;25) for the tongue (19), the perpendicular (N) of which in the locking position of the locking member passes through a torque axis (A) , which is parallel with the axis of rotation (B) of the locking member and which is so positioned in relation to the axis of rotation (B) of the locking member that a force on the tongue (19) in its direction (U) of withdrawal causes a resultant torque (M) on the locking member towards the release position of the locking member, so that it is easier to unfasten the safety belt, when the safety belt is loaded, and that the axis of rotation (B) of the locking member in the direction (U) of withdrawal of the tongue is positioned outside the contact surface (18; 25) of the locking member.

2. Locking device according to claim 1, characterized in that the resultant torque (M) at least partly compensates the frictional force at the surface where the tongue (19) is in contact with the lockin member (10; 23).

3. Locking device according to claim 2, characterized in that the resultant torque ( ) substantially completely compensates the frictional force al the surface where the tongue (19) is in c ntact w th the locking member (10; 3), when the tongue shall be released.

4. Locking device accordin to claim 2 or 3, characterized in that the contact surface (18:25) of the locking member (10; 23^ consists :^■_^" a c. r ion of a cylindrical surface, the radius of which has its centre on an axis (A) which is parallel with the axis of rotation (B) of the locking member and which is positioned above the axis of rotation of the locking means.

5. Locking device according to claim 4, characterized in that the centre, axis (A) of the cylindrical contact surface (18;25) is positioned in the locking member (10; 23).

6. Locking device according to any of the preceding claims, characterized in that the locking member (10) at each end is provided with a pocket (21) and in this pocket is mounted on a bearing edge (14:28) on a projecting lug (13; 27) in an aperture (12) of a load carrying side wall (11) and that the bearing edge has a radius of curvature with a centre axis (B) , so that the locking member rotates around a bearing axis through the centre (B) when it is moved between the locking position and the release position.

7. Locking device according to any of claims 1-6, the locking member being adapted to rotate about a fixed axis, characterized in that the resultant torque (M) is substantially as large as the maximum counteracting torque caused by the fric ional forces at the contact surface between the locking member (10) and the tongue (19), when the tongue is to be released.

8. Locking device according to any of claims 1-6, the locking member (10; 23) being movably mounted and arranged to come into contact with a load carrying surface when moved, characterized In that the resultant torque (M) is substantially as large as the counteracting torque caused by the frictional forces at the contact surfaces between the locking member (10; 23) and the tongue and the load carying surface.

9. Locking device according to claims 6 and 8, characterized in that the lug (27) provided with the bearing edge (28^"! is designed to yield when the safety belt is very heavily loaded, so that the locking, member (10) comes into contact with the edge of the aperture (12) in the load carrying sid<- wal 1 ⁽11 which ear" terms the load carrying surface.

10. Locking device according to claim 9, characterized in that the lug (27) is designed to rebound, when the very heavy load in the safety belt has ceased.

11. Locking device according to any of claims 1-5 and 8, characterized in that the locking member (23) is arranged to slide on a surface (24) and to rotate around an edge (B) on said surface when loaded, so that the locking member comes into contact with the load carrying surface.