GB2034395A

GB2034395A - Improvements in or relating to motor vehicle door locks

Info

Publication number: GB2034395A
Application number: GB7844311A
Authority: GB
Original assignee: CERDAN J
Current assignee: CERDAN J
Priority date: 1978-11-13
Filing date: 1978-11-13
Publication date: 1980-06-04
Also published as: GB2034395B

Abstract

A lock for a motor vehicle door comprises a forked bolt 7 whose formed by a front arm 13 and a rear arm 14. The forked bolt 7 is disposed in a housing 1 closed by a cover 2 and engages with a catch whose catching element 4 comprises a spindle 4 which engages in the bolt fork. There is provided a pawl 15, which is pivotable about a spindle 16 supported by the housing 1, for locking the bolt 7 in the closed position as a result of locking a first ratchet tooth 30 against the rear arm 14 of the bolt along a contact surface 31. A second tooth 24 of the pawl 15 is located, in the closed position, adjacent and in front of the front arm 13 of the bolt 7 and spaced therefrom. <IMAGE>

Description

SPECIFICATION Improvements in or relating to motor vehicle door locks The present invention relates to motor vehicle door locks. In such locks, a fork-shaped bolt, mounted rotatably in a housing rigid with the door, engages with a catch mounted on the door post and essentially constituted by a spindle. On closing, the forked bolt turns around its spindle due to the engagement of the fork and the spindle of the catch and is locked, generally in two successive locking positions, by a pawl engaging with a ratchet cam rigid with the forked bolt.

Motor vehicle door locks are subject to strict standards with respect in particuiar to their fracture strength. They must therefore, according to the so-called American standards, be able to resist a load of 907 kilogrammes applied transversally to the vehicle.

20% should be added to this value on account of the tolerances caused by mass production. in the present known fork type locks, the fork is back-balanced around a spindle, i.e. it turns around a fixed spindle, with only its front arm which ensures striking of the catch spindle and the pawl being pushed by a spring which engages with the opposite edge of the part constituting the fork, on which ratchet teeth are formed. Consequently the tooth of the fork must be able to resist a tearing force higher than one ton and the section of the bolt member surrounding the spindle, the ratchet teeth and the pawl must be able to resist the corresponding forces, which means that the lock parts must be constructed on a large-scale and the lock itself becomes cumbersome.

According to the invention, there is provided a lock for a motor vehicle door, comprising a forked bolt, whose fork is formed by a front arm and a rear arm, disposed in a housing closed by a cover, the bolt being arranged to engage a catch whose catching element comprises a spindle which is arranged to be engaged in the bolt fork, a pawl which is pivotable about a spindle supported by the housing for locking the bolt in the closed position as a result of the locking of a first ratchet tooth against the rear arm of the bolt along a contact surface, a second tooth of the pawl being located, in the closed position, adjacent and in front of the front arm of the bolt and spaced therefrom.

Preferably, the support surfaces between the bolt and the pawl in the closed position are perpendicular to the straight line passing through the pawl spindle and substantially radial with respect to the bolt spindle, a second ratchet tooth being placed in front of the front arm of the forked bolt at a slight distance from the latter.

The above feature of the support surfaces between the bolt and the pawl in the closed position enables any force components which turn the pawl in a release direction to be suppressed and, as a result of the positioning of the second ratchet tooth in front of the front arm of the latter, if the fork constituting the bolt tends to open when an abnormally high force is applied, the second ratched tooth resists the strain.

The invention will be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a sectional view of a preferred lock on a line I-I of Fig. 5; Figure 2 is a vertical view of the lock in the open position with the cover of the housing removed; Figure 3 is a view corresponding to Fig. 2 of the lock at the first stage of closing; Figure 4 is a view corresponding to Fig. 2 of the lock during transition from the first to the second closing stage; and Figure 5 is a view corresponding to Fig. 2 of the lock in the closed position.

The preferred lock comprises a housing 1 and a cover 2, the cover being fixed to the housing and the door assembly by means of screws or bolts described hereafter. The housing and the cover have a wide, open slot 3 for the engagement of the front and rear spindles 4 and 5 of a catch 6.

The lock is provided with a forked bolt 7 which is mounted rotatably in the housing around a spindle 8 and which is urged to rotate in an anticlockwise direction by a spiral spring 9 having a torsional effect wound around the spindle 8 and bearing between a rib 10 at the base of the housing and a release 11 on the edge of the lock member.

The lock member comprises, on the section of its periphery facing the slot 3, a notch 1 2 with a semi-circular base dividing the front arm 1 3 and the rear arm 1 4 of the fork. A pawl assembly 1 5 is articulated around a spindle 1 6 and has, in addition, a spindle section 1 7 which traverses the rear surface of the housing through a slot having the shape of an arc of a circle 18, centred on the spindle 1 6 so that the control device for opening the lock can be connected to the extension of this spindle section.It also has a slot in the shape of an arc of a circle 1 9 also centred on the spindle 1 6 wherein passes a spindle 20 which, similarly to the spindle 8, comprises a bushing 21 surrounding a screw 20 for fixing the lock to a door. A second spiral spring 22 is wound around this spindle and has a torsional effect, bearing between a rib 23 at the base of the housing and the spindle section 1 7 in order to urge the spindle section 1 7 to move in a clockwise direction about the spindle 16. The operative edge of the pawl is the edge which is turned towards the spindle 8 and has, moving away from the spindle 16, a tooth 24 whose lower edge rests, in the open rest position shown in Fig.

2, on an edge 26 opposite the notch 52 of the rear arm 14 of the forked bolt which is rounded in the form of a cam so that the forked bolt may freely turn clockwise against the action of the spring 9, pushing the pawl 1 5 back against the action of the spring 22.

Above the tooth 24, the edge of the pawl 15 is extended by a notch substantially in the form of the arc of a circle around the spindle 16 and an edge 27 (Fig. 3) which may form a cam by engaging with the edge 26 of the rear arm 14 of the forked bolt in order to allow the forked bolt to turn freely in a clockwise direction against the action of the spring 9 (Fig. 4) by pushing the pawl 1 5 back against the action of the spring 22. In contrast and as clearly shown in Fig. 3, when the nose 28 of the rear arm 14 of the forked bolt is resting against the section 25 of the notch with the rear edge 26 of the rear arm 14 resting against the section 27 of the notch in the edge of the pawl, the bolt cannot turn in an anti-clockwise direction, and this is the first stage of closing of the door.When the door is closed beyond this first closing stage, the pressure of the spindle 4 of the catch on the front edge of the rear arm 14 of the forked bolt makes the forked bolt turn in a clockwise direction, the rear edge 26 of the rear arm 14 which engages with the edge 27 of the pawl pushes the pawl and makes it turn in an anticlockwise direction until the nose 28 passes the nose 30 of the pawl (Fig. 4).

The edge 31 of the paw located above the nose 30 is concentric to the spindle 16. The pawl can therefore turn around the spindle 16 under the action of the spring 22 as soon as the nose 28 of the forked bolt has passed the nose 30. The line of the edge 32 of the notch 12 of the forked bolt has the same radius of curvature as the edge 31 of the pawl and, in the closed position of the door as shown in Fig. 5, its centre of curvature is at the centre of the spindle 16. Consequently, in the closed position, the two edges rest perfectly against one another and the force exerted on the pawl 15 as a result of the torque exerted on the forked bolt in order to prevent opening of the door corresponds to a radial force passing through the spindle 16.Thus the striking force being exerted on the pawl to prevent rotation of the forked bolt and opening of the door does not have any component of creating a torque enabling release of the pawl.

Furthermore, on closing and as shown in Fig. 5, the tooth 24 of the bolt which turns in a clockwise direction is engaged in front of the nose 33 of the front arm 13 of the forked bolt so that the nose 33 is opposite the edge 25 of the pawl from which it is only separated by a slight clearance. Thus if an excessive load was applied, and the fork of the bolt comprising the two arms 12 and t4 attempted to open, this would be prevented by the striking of the nose 33 against the section 25 of the pawl. The section of the edge of the nose 33 which moves behind the tooth 24 preferably has a form corresponding to that of the edge 25, i.e. in the closed position shown it is concentric with the spindle 1 6.

The operation of the lock is shown in the preceding description. In order to open the lock, the spindle end 1 7 is actuated to make the pawl 15 turn against the action of the spring 22 in an anticlockwise direction until the nose 28 of the front arm of the bolt is released from the nose 30 of the pawl, the nose 33 of the front arm 1 3 of the bolt then also being released from the tooth 24 of the bolt.

Claims

1. A lock for a motor vehicle door, comprising a forked bolt, whose fork is formed by a front arm and a rear arm, disposed in a housing closed by a cover, the bolt being arranged to engage a catch whose catching element comprises a spindle which is arranged to be engaged in the bolt fork, a pawl which is pivotable about a spindle supported by the housing for locking the bolt in the closed position as a result of the locking of a first ratchet tooth against the rear arm of the bolt along a contact surface, a second tooth of the pawl being located, in the closed position, adjacent and in front of the front arm of the bolt and spaced therefrom.

2. A lock as claimed in claim 1, in which the perpendiculars to the contact surface between the first ratchet tooth and the rear arm of the bolt pass close to the pawl spindle, the plane tangent to the contact surface in the central area thereof passing through or close to the bolt spindle.

3. A lock as claimed in claim 1 or 2, in which the edge of the second ratchet tooth, which is located in front of front arm of the bolt is a cylindrical surface having as its axis the axis of rotation of the pawl and provides a first closing stage by engaging in front of the rear arm of the bolt.

4. A lock as claimed in claim 3, in which the section of the front arm of the bolt which is located opposite the second ratchet tooth has a cylindrical surface of radius substantially equal to or slightly more than that of the cylindrical surface forming the edge of the second ratchet tooth, the two cylindrical surfaces having a substantially constant distance between each other.

5. A lock for a motor vehicle door, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

6. A motor vehicle door provided with a lock as claimed in any one of the preceding claims.