The buckle comprises a substantially U-shaped channel which is adapted to be connected to an anchoring point Pivotally mounted on the channel is a locking member, the locking member having a locking section, typically in the form of a claw, which is directed downwardly towards the base of the channel. With the locking member in an initial position, in which the claw is spaced from the base of the channel, a tongue which is connected to part of the safety belt may be slid into the buckle adjacent the base of the channel. Subsequently, the locking member may move to a locking position in which the locking section moves in a direction towards the base of the channel and engages an abutment provided on the tongue, thus retaining the tongue in the buckle.

In a preferred embodiment, two locking sections are provided on the locking member, located adjacent the sides of the channel, the locking sections being adapted to engage abutment surfaces defined by a generally"T"-shaped head provided on the tongue.

A securing element is provided which has its opposed ends guided in two elongate slots formed in the side walls of the channel. The securing element may move from a position in which it is located immediately above the locking section, or sections, thus securing the locking member in the locking position, to a position where it is spaced from the locking section or sections, thus permitting the locking member to move to the release position.

It is intended that when a buckle of this type is in use, with the tongue in position in the buckle, the locking section or sections of the locking member firmly engage the tongue, preventing the tongue from being withdrawn from the buckle, whilst the securing member secures the locking members in the locking position. For the tongue to be released from the buckle, the securing member must be moved, against a spring bias, to a position in which the locking member may move to the release position, and the locking member must actually move to the release position before the tongue can be withdrawn from the buckle. It has been found that when a buckle of this type is subjected to very high accelerations, in some specific direction as might be experienced during an accident, there is a risk that the securing member may be moved away from the retaining position and the locking section of the locking member may move away from the locking position, thus inadvertently releasing the tongue from the buckle.

A number of buckles have been proposed previously which incorporate design features such mat the forces on the components of the buckle that are generated when the buckle is subjected to high acceleration, are effectively balanced out, so that the buckle is intended to remain in the locked condition even when subjected to a high acceleration. It has been found, however, that there are many problems in designing a buckle in which the forces applied to the components of the buckle are balanced, so that the buckle remains locked, in view of the fact that the buckle may be moved around one of many different axes when mounted in a vehicle that is involved in an accident. Because it is difficult to predict the precise axis about which a buckle is to be rotated, it is consequently tifficult to design the components of me buckle so that the forces applied to those components will remain"balanced".

The present invention seeks to provide an improved buckle.

According to this invention there is provided a safety belt buckle, the safety belt buckle comprising an element adapted to be connected to an anchoring point in a vehicle, a locking member connected to said element for movement between a locking position and a release position, a tongue, adapted to be mounted on a vehicle seat belt, and being adapted to be inserted into the buckle when the locking member is in the release position, the tongue being provided with abutment means adapted to engage part of the locking member when the locking member has been moved to the locking position to prevent withdrawal of the tongue from the buckle, the buckle further comprising a blocking element, the blocking element initially occupying a position in which the locking member can move between the locking position and the release position, means being provided to move the blocking element to a second position in which the locking member is retained in the locking position, the means to move the blocking element to the second position being actuated by a sensor, the sensor being adapted to respond to an impact or conditions indicative man an accident is likely to occur.

The sensor may comprise an impact sensor or an accelerometer.

The moving means may comprise a solenoid or a pyrotechnic device adapted to move the blocking element.

The sensor and means to move the blocking element may be such that the blocking element may return to its initial position after a predetermined period of time.

In one embodiment the buckle inclues a securing member, the securing member being movable between two positions, the securing member acting to prevent movement of the locking member to the release position when the securing member is in the first position, whilst pennitting said movement when the securing member is in the second position, the blocking element, in the second position, engaging said securing member to retain said securing member in its said fust position.

In an alternative arrangement the blocking means move in a direction perpendicular to the direction of movement of the locking member, the blocking means, when in the retaining position, blocking movement of the locking member.

In one embodiment there is provided a sensor to sense the locked condition of the buckle to enable actuation of the moving means.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings in which: FIGURE 1 is a diagrammatic view illustrating various components which form part of a buckle in accordance with the invention, with the buckle being shown in the ordinary locked condition, FIGURE 2 is a view of the components shown in Figure 1, illustating the buckle in the release condition, FIGURE 3 is a view illustrating the components of Figure 1, illustrating the situation when an accident has been sensed.

Referring initially to Figure 1 of the accompanying drawings, a buckle 1 is schematically illustrated The buckle comprises a substantially"U"-shaped channel, with a base 2, the channel being secured, by appropriate means, to an anchor point within the vehicle. An aperture 3 is formed in the base of the channes A locking member 4 is provided which is pivotally mounted at a pivot point 5 to the side walls of the channel to effcct a pivotal movement between a locking position, which is shown in Figure 1, and a release position which is shown in Figure 2. The locking member 4 is provided, at a region spaced from the pivot point 5, with downwardly directed locking sections 6 which, in the embodiment illustrated, are co-aligaed with the aperture 3 formed in the base 2 of the channel. The locking sections 6 may comprise downwardly directed claws.

The side walls of the channel are each provided with L-shaped slots which will guide a securing member 7 which can move firom a securing position shown in Figure 1 to a non-securing position shown in Figure 2.

When the securing member is in the securing position, upward movement of the locking member 4 towards the release position is prevented.

A tongue 8, which may be connected to a vehicle seat belt is provided which can be inserted into the buckle, with the tongue 8 being inserted along a path which lies adjacent the base 2 of the channel. The tongue 8 is provided with an abutment 9, which may be formed as part of a'Y'-shaped head of the tongue, adapted to engage with the locking sections 6 of the locking member 4.

As can be seen from Figure 1, when the buckle is in the locked condition, the tongue is inserted into the buckle, so that the abutment 9 is generally aligned with the inner-most end of the aperture 3, and the locking member 4 had been moved about the pivot point 5 to a position in which the locking sections 6 extend past the abutment 9 and through the aperture 3 formed in the base 2 of the channel. The securing member 7 is located immediately above the locking member 4 to retain it in the locking position. If a generally outward force is applied to the tongue 8, as indicated by the arrow 10, movement of the tongue will be prevented when the abutment 9 engages the locking sections 6. If a very heavy force is applied to the tongue 8 in the direction of the arrow 10, the locking sections 6 may be deformed slightly, but as a consequence of this deformation, the locking sections 6 will engage the side of the aperture 3 which is spaced furthest from the pivot point 5, and further withdrawal of the tongue 8 from the buckle will be prevented.

In the embodiment described, a crash sensor 11 is provided which may comprise any appropriate sensor which senses a parameter indicative of an accident, or which indicates an increased likelihood of an accident arising.

Thus the sensor 11 may, for example, comprise an impact sensor, or an acceleration sensor. The sensor incorporates a timer and thus provides an output signal which lasts for a predetermined period of time whenever a parameter indicative of an accident is sensed. The timer may, for example, be such that an output signal having a duration of one second is generated The output of the sensor 11 is supplied, in the illustrated embodiment, to a solenoid 12, which is mounted in position on the"U"-shaped channel. The solenoid 12 is provided with a projecting pin or armature 13 which, when the solenoid is activated, is caused to extend outwardly from the solenoid 12. The pin or armature 13 engages a pivotally mounted blocldng arm 14.

Figure 2 illustrates the components of Figure 1 when the buckle is in the release condition. It can be seen that the securing member 7 has moved along the L-shaped slots formed in the side walls of the channel to an elevated position, thus permitting pivotal movement of the locking member 4. The locking member 4 has pivoted upwardly about the pivot point 5, relative to the position shown in Figure 1. Thus, the locking sections are totally disengaged from the aperture 3, and are not adjacent the abutment 9 provided on the tongue 8. The tongue 8 may, with the buckle in this condition, be freely withdrawn fim the buckle.

In order to prevent the locking member inadvertently moving to the position shown in Figure 2, (for example if the buckle is subjected to very high acceleration forces during an accident), when an accident is sensed by the sensor 11, the sensor supplies an electric current to the solenoid 12 and, as a consequence, the pin 13 is moved to a position in which it extends fully from the solenoid 12. The pin 13 moves the blocking arm 14, which is pivotally mounted on the walls of the channel into a position in which it will block movement of the securing member 7. This prevents pivotal movement of the locking member 4 towards the release position. Thus, when an accident situation is sensed by the sensor 11, the solenoid 12 operates to ensure that the buckle is maintained in the locked condition for a predetermined period of time as determined by the timer incorporated within the sensor, and the blocking arm 14 acts as a blocking element or a retaining element to retain the locking member in the locked position. It is to be appreciated that after the termination of the period of tune measured by the timer incorporated within the sensor, the output signal from the sensor 11 terminates, and me solenoid 12 rectums to its initial position.

Consequently it is to be appreciated that in an accident situation the buckle is prevented inadvertently moving to the release position in which the tongue is released from the buckle for the peri. od of time that an output signal is provided by the sensor. Following the accident, no signal is produced by the sensor, and the buckle can then be released to permit an occupant of the vehicle to escape from the vehicle.

It is to be appreciated that whilst one embodiment of the invention has been described, with schematic illustrations, many modifications may be effected. For example, whilst the solenoid 12 is positioned, in the illustrated embodiment, to direct the pin 13 in such a way that it tends to force the blocking arm towards the blocking position, it is to be appreciated that the pin could move transversely of the path of movement of the locking member so that the pin itself blocks movement of the locking member, and prevents the locking member from moving towards the release position, thus retaining the locking member 4 in the locking position.

Also, whilst in the described embodiment a solenoid is dcscribed as being provided to move the pin 13, other appropriate means could be utilise, such as a small pyrotechnic device.