Buckle For Safety Belts

Abstract

A safety belt buckle including a pair of mutually spaced lockplates, a push button the outer surface of which extends flush with a narrow side of the buckle housing, a latch member slidably received between the lock plates, coupled to the push button and adapted to lock or to release a safety belt connector inserted into the buckle, and a spring for biasing a connector end portion and the latch member.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a buckle for a safety belt, particularly for a motor vehicle safety belt which buckle includes a shallow housing enclosing a locking mechanism operated by a push button and adapted to receive a plate-shaped slide-in tongue connected to the safety belt wherein the slide-in tongue is provided with an indentation in either of its mutually opposing lateral edges.

There are already known safety belt buckles provided with a push button for unlocking the buckle wherein the push button is arranged on the upper surface of the housing or on the shallow surface thereof respectively. In these prior art buckles, when unlocking the buckle the push button movement perpendicular to the plane of the housing must be translated into a movement which is perpendicular to the original movement and occurs in the plane of the housing, by auxiliary means such as levers or the like, when the latch member is adapted to be brought by a sideways movement into engagement with an indentation in the narrow side of the slide-in tongue. Because of these auxiliary means the buckle, i.e., the buckle housing is relatively thick, i.e., of a relatively large height. Furthermore, because of the larger number of components required such prior art buckles are expensive to manufacture and to assemble and are additionally susceptible to trouble. As a remedy, it has been proposed to provide buckles of this type with one lock plate only. This, however, entails a relatively high loading of the components which are mounted on this lock plate, especially in the bearing areas thereof when the user of the buckle is involved in an accident. This high loading results in the risk of breakage of components. For this reason it is more advantageous to provide buckles having a pair of lock plates between which the slide-in tongue may be inserted, because in such arrangements the various components that are mounted in the pair of lock plates will be subject to only half of the total load at either side.

Another drawback of prior art safety belt buckles is that a push button for unlocking the buckle arranged on one of the shallow surfaces of the buckle increases the risk of inadvertently releasing the buckle when the shallow surface of the buckle at which the push button is mounted faces the body of the passenger and the passenger moves towards the buckle.

In other types of prior art buckles the push button must be operated to allow insertion of the slide-in tongue. Buckles of this type do not allow an advantageous one-hand operation.

It is therefore the object of the present invention to provide a novel and improved safety belt buckle.

It is another object of the invention to provide a buckle for a safety belt having a slide-in tongue wherein the push button of the buckle is arranged along the narrow side of the buckle housing.

It is a further object of the invention to provide a buckle of the above type which buckle has only a minimum number of components.

SUMMARY OF THE INVENTION

For achieving the above stated objects the invention proposes a buckle having a pair of similar mutually spaced lock plates each of which provided with a guide groove extending perpendicularly to the slide-in direction of the slide-in tongue, and further a latch member slidably received in these grooves, the latch member biased by a spring and coupled directly to a push button adapted to move the slide-in tongue into an unlocked position when pressed down perpendicularly to the slide-in direction of the slide-in tongue in a direction parallel to an upper surface of the housing.

A buckle of this type may be more easily and safely manipulated and may be designed in a very shallow configuration by using a minimum number of components. The force required for unlocking the buckle may be reduced still further when the sliding surface of the indentations in the slide-in tongue and the sliding surface of the latch member which surfaces are in the locking position in mutual engagement are obliquely inclined downwardly wherein the sliding surfaces preferably are at an inclination of about 7.degree. with respect to a horizontal line (when the longitudinal center line of the buckle is coextensive with the vertical). Such an angle of inclination allows to substantially reduce the friction forces between latch member and slide-in tongue which must be overcome when unlocking the buckle. This magnitude of inclination of the sliding surfaces on the other hand assures that no inadvertent release of the buckle may occur even under an extremely high loading. The simplicity of the buckle design may be further enhanced by using in the buckle only a single helical spring having two free legs one of which engages the lower edge of the slide-in tongue and the other of which engages the latch member. A spring of this type may perform three functions, i.e., to automatically eject the slide-in tongue when depressing the push button, to secure the latch member in the locking position and to reset the push button after the buckle has been opened. The push button is provided with a head portion and preferably received with this head portion in mating recesses of the pair of lock plates so that the upper surface of the push button is flush with the housing surface. By this arrangement any inadvertent opening of the buckle will be safely avoided.

Although in the buckle of the present invention the slide-in tongue is retained by a single latch member disposed on one side of the tongue it will be advantageous if the slide-in tongue is made symmetrical with respect to a longitudinal center line of the tongue thus allowing to introduce the tongue into the buckle with either the upper or the lower surface of the tongue facing upwardly or respectively downwardly.

DESCRIPTION OF THE DRAWINGS

In the following, a preferred embodiment of the invention will be described in detail with reference to the appended drawing wherein

FIG. 1 is a longitudinal section view of the safety belt buckle with the slide-in tongue inserted therein, according to the present invention, and

FIG. 2 is a lateral sectional view of the safety belt buckle of FIG. 1.

FIG. 3 is a longitudinal sectional view of the safety belt buckle with the slide-in-tongue being disengaged.

The safety belt buckle shown in the drawing includes a pair of similar lock plates 1 and 2. These two lock plates are held in a mutual spaced relationship parallel to each other by means of connecting lugs 3 and a sleeve 4. On their outer surfaces the lock plates 1 and 2 are enclosed by a housing 5 made of a plastic material. This housing 5 is provided at its upper edge portion with an opening 6 for inserting a slide-in tongue 7. In the region of this opening 6 the two lock plates 1 and 2 are bent outwardly in the form of a hopper as may be seen in FIG. 2, in order to facilitate the insertion of the slide-in tongue and to guide the same.

The slide-in tongue 7 is rigidly connected at a mounting 8 with a safety belt not shown in the drawing, and is furthermore tapered towards its lower end and symmetrical with respect to the longitudinal center line 9. The two outwardly facing edge portions of the slide-in tongue 7 are each provided with a recess 10 in the form of an indentation The lower edges of these indentations are obliquely inclined with respect to a horizontal line and enclose therewith an angle .alpha. of 7.degree. 30'.

Each of the pair of lock plates 1 and 2 is provided with a guide groove 12 extending perpendicularly to the longitudinal center line 9. These grooves 12 serve to slidably and reciprocally guide a latch member 13. A pair of webs 14 and 15 provided at the lower end of a push button 16 are rigidly connected to the latch member 13. The push button 16 has a head portion which is received in mating recesses 17 of the two lock plates 1 and 2 so that the head portion of the push button does not project beyond the outer surface of the casing 5.

A spring 18 engages with the end of its free leg 19 the outer surface of the latch member 13 and biases the latch member towards the longitudinal center line 9. The second leg 20 of the helical spring 18 is provided with an offset or bent portion guided in a groove 21 and engages the lower edge of the slide-in tongue 7. The buckle furthermore includes a spacer 22 made of a plastic material which is inserted between the pair of lock plates 1 and 2 and an abutment or opposed support member 23 for the slide-in tongue 7.

To open the buckle, the push button 16 will be pressed into the housing 5 in the direction shown by the arrow 24. During this movement the webs 14 and 15 of the push button 16 entrain the latch member 13 against the opposing force exerted by the leg 19 of the spring 18. Since the latch member 13 is likewise provided at its lower edge with an inclined sliding surface similar to the lower edge of an indentation 10 a relatively low pressure force will be sufficient to open the safety belt buckle. As soon as the latch member 13 has been completely disengaged from the indentation 10 the pressure applied by the leg 20 of the spring 18 against the lower surface of the slide-in tongue 7 results in the ejection of the slide-in tongue 7 in an upward vertical direction. Toward this end, the spring 18 includes two helical coils and is arranged such that when ejecting the slide-in tongue 7 the one coil 25 moves upwardly together with the tongue while the second coil 26 of the spring 18 abuts against a support surface of the spacer 22.

When using the buckle it will be merely necessary to insert the slide-in tongue 7 into the opening 6 and to urge the tongue 7 downwardly against the force of the spring 18. Since the lower corners of the tongue are curved the latch member 13 will be moved outwardly by this movement against the force of the spring 18 and finally engages into an indentation 10 under the force of the spring 18 so that the head portion of the push button 16 automatically returns into the position shown in FIG. 1.

Claims

Having described the invention, the embodiments thereof in which an exclusive property or right is claimed are defined as follows:

1. A buckle for a safety belt, the buckle comprising a housing enclosing a locking mechanism, a push button mounted in said housing and disengaging said locking mechanism, said housing receiving a flat tongue engaged by said locking mechanism and connected to the safety belt when directed into the buckle, said tongue provided with at least one indentation therein, said locking mechanism comprising a pair of lock plates, each provided with a guide groove extending perpendicularly to the direction of entry of the tongue in the buckle, said tongue moving in said buckle between said lock plates, and further comprising a latch member for reception in said indentation for engaging said tongue in said buckle slidably received in said grooves, the latch member biased in the locking position by a spring mounted in the buckle and coupled directly to the push button for movement on depression of said button perpendicularly to the movement of said tongue in said buckle, said buckle further comprising a pair of webs rigidly connecting said latch member to said push button, each web of said pair of webs being arranged parallel to said lock plates and on the outside of one of said pair of lock plates.

2. A buckle for a safety belt, the buckle comprising a housing enclosing a locking mechanism, a push button mounted in said housing and disengaging said locking mechanism, said housing receiving a flat tongue engaged by said locking mechanism and connected to the safety belt when directed into the buckle, said tongue provided with at least one indentation therein, said locking mechanism comprising a pair of lock plates, each provided with a guide groove extending perpendicularly to the direction of entry of the tongue in the buckle, said tongue moving in said buckle between said lock plates, and further comprising a latch member for reception in said indentation for engaging said tongue in said buckle slidably received in said grooves, the latch member biased in the locking position by a spring mounted in the buckle and coupled directly to the push button for movement on depression of said button perpendicularly to the movement of said tongue in said buckle, said spring having two integral free legs, one of which engages the lower edge of said tongue and the other of which engages said latch member.