Motor vehicle door lock

The invention relates to a motor vehicle door lock equipped with a locking mechanism (1, 2, 3), an actuation lever unit that acts on the locking mechanism (1, 2, 3) and includes a release lever (4), and a catch lever (10). The catch lever (10) blocks the locking mechanism (1, 2, 3) at least when acceleration forces of a given magnitude occur, e.g. in case of an accident (crash). According to the invention, the catch lever (10) blocks the locking mechanism (1, 2, 3) in the event of a crash while releasing the locking mechanism (1, 2, 3) only for normal opening operation.

The invention relates to a motor vehicle door lock with a locking mechanism, an actuation lever unit with a release lever acting on the locking mechanism and a catch lever, blocking the locking mechanism at least when acceleration forces of a given magnitude occur, e.g. in case of an accident (crash).

The actuation lever unit generally comprises one or several levers. Normally, the unit contains at least an internal actuating lever, an external actuating lever and a release lever. In addition, the actuation lever unit also often contains a coupling lever. When the actuation lever unit is acted upon, the locking mechanism can be opened in this way. For this purpose, the release lever typically engages with a pawl of the locking mechanism and lifts it off an associated rotary latch. The rotary latch then opens with the assistance of a spring and releases an engaged locking bolt. As a result, an associated motor vehicle door can be opened.

In case of an accident or in the event of a crash, as mentioned above, high acceleration forces occur in most cases, which can be several times greater than the earth's acceleration. The respective motor vehicle door lock is thus exposed to considerable inertia forces which could cause an unintentional opening of the locking mechanism and thus of the entire associated door lock.

These described scenarios represent considerable hazards for vehicle users. A motor vehicle door opened unintentionally can, for instance, no longer provide any safety devices contained therein, such as a side airbag or side impact protection for the protection of the passengers of the vehicle. For this reason, various measures were already implemented in the past that either block the actuation lever unit or the locking mechanism during the occurrence of the described abnormal acceleration forces, e.g. in the event of a crash. In these cases, a so-called inertia lock is used, which is in its rest position under normal operating conditions and is not engaged in the actuation lever unit or the locking mechanism.

A catch lever acting on the actuation lever unit is, for instance, disclosed in DE 197 19 999 A1. The lock or catch lever blocks an opening lever when the described acceleration forces are exerted in case of an accident. For this purpose, the lock or the catch lever and the opening lever are arranged transversely to the swivel direction of the opening lever and are displaceable in relation to each other. In case of a relative displacement caused by increased acceleration forces, the opening lever enters the lock. This aims to prevent unwanted opening in the event of a crash whilst keeping the design simple. A permanent blocking of the opening lever is also generally discussed.

The generic state of the art of DE 19910 513 A1 describes a crash catch on a door lock. This catch contains a pivotable catch lever, which can be pivoted by inertia force around its swivel axis into a blocking position stopping the transmission element. Also, a counter blocking surface is provided, which is fixed in position.

Not all aspects of the prior art are satisfactory. The systems generally work in that the catch lever blocks the actuation lever unit or locking mechanism only during the occurrence of abnormal acceleration forces, e.g. in the event of a crash. In practical application this can result in incorrect functioning, for instance, in case that the movement of the catch lever is blocked or delayed due to corrosion or ageing, etc. Such functional faults can also not be checked, for instance, as part of maintenance, as the catch lever has to be moved, which is not possible in practical application. The invention aims to remedy this situation.

The invention is based on the technical problem of further developing such a motor vehicle door lock in such a way that functional reliability is increased, whilst keeping the design simple.

To solve this technical problem, a generic motor vehicle door lock of the invention is characterized in that the catch lever during non-actuated normal operation and in the event of a crash blocks the locking mechanism and only releases it for normal opening operation.

As part of the invention, the catch lever is thus practically in a permanently active state. For blocking the locking mechanism in the non-actuated state, i.e. in case that the motor vehicle door lock is at rest and the locking mechanism is not deflected, the catch lever is in a blocking position. Typically, the deflected locking mechanism during normal operation causes it to be opened. For this purpose, the pawl is in most cases lifted off the rotary latch.

The last described functional state of the opening of the locking mechanism corresponds to the normal opening operation, provided no excessive acceleration forces are applied to the respective motor vehicle door lock.

The design of the invention is in any case such that the catch lever in the non-actuated state is in the blocking position. The same applies in case of a crash, i.e. the catch lever does not even change its relative position compared to the locking mechanism in case of a crash and blocks a movement of the locking mechanism. This is mainly due to the fact that the catch lever as such is balanced, i.e. that the centre of gravity is at the pivot point of the catch lever.

In detail, the catch lever is typically a swivel lever rotatable around an axis. In this arrangement, the catch lever is in most cases positioned in a lock case together with the locking mechanism, providing the aforementioned components and their mounting with the required rigidity and positional accuracy. The catch lever is generally a two-arm lever consisting of a blocking arm and a compensation arm. The catch lever is also preferably coupled to the actuation lever unit.

At this point an elastic coupling has proven to be particularly advantageous. In most cases this is provided by a spring, connecting the catch lever and the actuation lever unit. Generally, the spring engages with the blocking arm of the catch lever and always in such a way that the catch lever is released during normal operation and thus releases the locking mechanism.

In detail, the catch lever is connected to a release lever of the actuation lever unit. The release lever acts as usual on the blocking pawl of the locking mechanism, i.e. to open it by lifting it. So as soon as the release lever is displaced to remove the blocking pawl from the pawl and to lift the pawl from the rotary latch and thus open the locking mechanism, this swivel movement also ensures that the catch lever is acted upon by the spring. During normal operation this deflection of the release lever causes the catch lever to be “carried along” by the spring between the release lever and the catch lever. The catch lever can consequently not block the locking mechanism in the described opening normal operation.

In normal operation during a non-actuated state the catch lever rests instead in the blocked position loosely against the blocking pawl and blocks said pawl in case of a crash. This is achieved by a spring, returning the catch lever after deflection back to the normal position for the non-actuated state.

The accelerations associated with such a crash generally cause the actuation lever unit to be deflected and also deflect the release lever, as if the pawl is to be lifted from the rotary latch. The mass moment of inertia of the catch lever does, however, ensure that the catch lever does not follow the deflection of the release lever in this crash situation. Instead, the catch lever and the blocking pawl, pressing against the blocking lever as a result of the crash, remain unchanged in its blocking position.

The mass moment of inertia of the catch lever is designed in such a way that even the spring between the release lever and the catch lever and tensioned by the release lever cannot displace said lever.

This shows in any case that the catch lever can block the locking mechanism in case of a crash, when the mass of the lever unit and locking mechanism and the tensioned spring, coupling the release lever and the catch lever cannot overcome the moment of inertia of the catch lever. Consequently, no relative movement takes place between the blocking pawl and the catch lever in case of a crash. In case of a crash, the catch lever thus provides the desired blocking of the locking mechanism.

A further advantageous embodiment provides for the coupling between the catch lever, on one hand and the locking mechanism, on the other hand, to be arranged, for instance, by a cam, a deformation, etc. For this purpose, the catch lever can contain the respective cam or a deformation, interacting with the blocking pawl. Naturally, a reverse arrangement is also possible. In this case it is not the catch lever but the blocking pawl of the locking mechanism that contains the respective cams, the deformation, etc. The shape has to be designed in such a way that the blocking pawl turning in open direction cannot induce an opening torque in the catch lever.

As a result, a motor vehicle door lock is provided, which first of all provides a high level of functional reliability, as the catch lever assigned to the locking mechanism is basically actuated during every deflection in normal operation. For this purpose it is only necessary that the release lever of the actuation lever unit is pivoted into the locking mechanism in the opening sense. During this process, the release lever carries along the catch lever through the interposed spring so that, as a result, the blocking pawl is no longer blocked and can be lifted off the rotary latch by the release lever.

This movement of the catch lever occurring during every opening operation of the locking mechanism, ensures that its functionality practically corresponds to that of the entire motor vehicle door lock. Any functional faults due to corrosion, etc. do not (no longer) occur. All of this is achieved with a simple design limited to a few elements, which is consequently low in cost and quick to produce. These are the main advantages of the invention.

To open the locking mechanism1,2,3, the release lever4must be pivoted clockwise around its axis5, as shown by the arrow in the FIGURE. As a result, an edge6of the release lever4engages with a journal6′ of the blocking pawl2. This causes the blocking pawl2to turn counter-clockwise, as shown by the arrow, around its axis7. As soon as the blocking pawl2has been lifted off the pawl3, the rotary latch1can turn clockwise around its axis8by means of the spring and release a latch bolt9, only indicated in the FIGURE. The latch bolt9is connected to a motor vehicle door, also not shown.

The further basic design includes a catch lever10, rotatably mounted around an axis11. The axis8of the rotary latch1, the axis7of the blocking pawl2, the axis5of the release lever4and finally the axis11of the catch lever10are all defined in a lock case12. These may be bearing journals essentially arranged in parallel and mainly extend perpendicularly from a base of the lock case12. This represents naturally only an example and is not limiting the scope of the invention.

The catch lever10is designed as a swivel lever10rotatable around its axis11. As already explained, the catch lever10and the locking mechanism1,2,3are arranged in the lock case12. The catch lever10is a two-arm lever consisting of a blocking arm10aand a compensation arm10b.

The blocking arm10arepresents the arm of the catch lever10facing the blocking pawl2, whilst the compensation arm10bis facing away from the blocking pawl2. In the embodiment the blocking arm10acontains a recess or respective deformation13with which the edge13′ of the blocking pawl2engages. Naturally, also a reverse arrangement is possible. In this case, the blocking pawl2contains a deformation13and the catch lever10features a corresponding edge13′.

Another option is a cam on the blocking pawl2or on the catch lever10, which is also part of the scope of the invention. The catch lever10ensures in any case during normal operation shown in the FIGURE that the blocking pawl2is blocked in case of a crash and cannot carry out the counter-clockwise movement around axis7during opening, as indicated in the drawing, which is initiated by the release lever4during its actuation. In other words, the locking mechanism1,2,3is blocked, as the catch lever10blocks the blocking pawl2as described.

It is apparent that the catch lever10is coupled with the release lever4. At this point an elastic coupling in form of a spring14is actually provided. This spring14connects the catch lever10and the release lever4. Preferably the spring14engages a blocking arm10aof the catch lever10.

Finally, the design of the embodiment is such that the respective axes5,7of the release lever4and the blocking pawl2are arranged on a connecting line with the catch lever10being arranged below the line. In other words, the catch lever10is positioned below the connection line of the two axes5,7of, on one hand the release lever4and, on the other hand, the blocking pawl2.

The arrangement functions as follows. In the FIGURE, the locking mechanism1,2,3is in its closed state. The pawl3has engaged in the rotary latch1. The rotary latch1is in its fully closed position. The FIGURE also shows the non-actuated state, i.e. the rest position.

As soon as the release lever4is acted upon in this position whilst not subjected to any abnormal acceleration, i.e. during a normal situation, the release lever4is acted upon in such a manner that it carries out the clockwise movement around axis5, as indicated. This pivoting movement of the release lever4ensures that the catch lever10is also rotated around its axis11. This is ensured by spring14, coupling the release lever4with the catch lever10. During this process the catch lever10is pivoted around its axis11in counter clockwise direction, as shown by an arrow in the FIGURE (opening case).

This means that starting from the normal operation the release lever4and the catch lever10move synchronously when the release lever4is deflected. During this process the catch lever10releases the previously blocking pawl2. As a result, the actuation edge6of the release lever4can act upon the blocking pawl2or its journal6′ during continued movement.

As a result, the actuating edge6engaging with the blocking pawl2ensures that the blocking pawl2carries out the counter-clockwise movement around its axis7, indicated in the FIGURE. The pawl3can subsequently be lifted off the rotary latch1, which in turn opens with the assistance of the spring and releases the previously engaged latch bolt9. This corresponds with the normal operation in which the catch lever10releases the locking mechanism1,2,3or the blocking pawl2.

During closure of the locking mechanism1,2,3a spring, not shown, on the blocking lever10ensures that with the release lever4being moved to its original position, the blocking lever is also returned to its non-actuated state, the rest position.

Where, during normal operation corresponding to the functional position shown in the FIGURE, a crash occurs, the release lever4can be deflected, depending on the acceleration forces generated and on the direction of the applied force. In other words, the release lever4would experience a comparable force in clockwise direction around its axis5as during a “normal” actuation. In contrast to this “normal” actuation, inertia forces act on the catch lever10and the blocking pawl2blocked by the lever in case of a crash. The mass moment of inertia of the catch lever10is designed in such a way that the described crash scenario does not cause a relative movement of the catch lever10and the blocking pawl2is blocked by the catch lever10.

The design also ensures that the release lever4deflected in case of an assumed crash can also not deflect the catch lever10with the thus tensioned spring14and that the locking mechanism1,2,3is consequently blocked.