CAR LOCK

Description

[0001] The invention relates to a motor vehicle lock according to the preamble of claim 1.

[0002] The motor vehicle lock in question is used for all types of locking elements of a motor vehicle. These include, for example, side doors, especially sliding doors, tailgates, trunk lids, hoods, cargo floor, etc. of a motor vehicle.

[0003] The requirements placed on the vehicle lock in question are often contradictory. On the one hand, there is the requirement for low operating force for opening, and on the other hand, the requirement for a secure holding function. For example, vehicle locks are known from DE 10 2009 021 297 A1 and CZ 2015-388 A3.

[0004] The known motor vehicle lock (DE 20 2013 004 589 U1), from which the invention is based, has a latch and a primary locking pawl associated with the latch. To ensure low operating force for opening the motor vehicle lock, the primary locking pawl, in the main locked position, engages the latch and moves into its release position. The primary locking pawl is thus equipped with an opening tendency that allows a release movement of the primary locking pawl to be generated by an opening torque acting on the latch. This release movement is prevented by a secondary locking pawl, which can be released from engagement with the primary locking pawl with a comparatively low operating force. No such opening tendency is provided in the pre-locked position.The reason for this is that the opening torques acting on the lock latch are significantly lower in the pre-locked position, making the required actuation force less problematic. Nevertheless, the actuation force required from the pre-locked position can still be considerable.

[0005] The invention is based on the problem of designing and further developing the known motor vehicle lock in such a way that the actuating force for opening the motor vehicle lock is further reduced using simple means.

[0006] The essential consideration is that, for a reliable holding effect between the primary locking pawl and the latch, it is only necessary to ensure that the latch and the pawl form a self-locking mechanism via the locking engagement between the latch and the pawl. It has been proposed that such self-locking can be achieved even if the normal force acting on the primary locking pawl at the locking engagement point generates a lifting moment on the primary locking pawl. According to the proposal, this self-locking is achieved by generating a corresponding static friction force at the locking engagement point. In this context, the self-locking ensures that even a theoretically infinite opening moment of the latch cannot generate a lifting movement of the primary locking pawl.

[0007] At the same time, the proposed solution achieves a reduction in the actuating force required to lift the primary locking pawl, i.e., the actuating force required to overcome static friction, in view of the lifting moment already acting on the primary locking pawl.

[0008] Specifically, it is proposed that in at least one closed position, here and preferably in the pre-locked position, an opening moment acting on the latch, via the locking engagement, generates on the one hand a lifting moment at the primary locking pawl and on the other hand a static friction force at the locking engagement point between the latch and the pawl, such that the latch and the pawl form a self-locking mechanism via the locking engagement. The lifting moment at the primary pawl results from the fact that the normal of the respective locking surface associated with the latch passes the pivot axis of the primary pawl at the locking engagement point between the latch and the primary pawl.

[0009] As proposed, a reliable holding effect of the lock latch can be achieved by the primary locking pawl, while at the same time ensuring a particularly low actuating force for opening the vehicle lock.

[0010] The preferred embodiments according to claims 2 and 3 relate to preferred geometric design variants for the interlocking surfaces of the latch and the locking pawl at the locking engagement point. It is evident here that the proposed solution can be implemented in a particularly simple manner by appropriately designing the relevant locking surface on the latch.

[0011] The further preferred embodiments according to claims 4 to 7 relate to advantageous variants for the design of the coefficient of static friction at the locking engagement point. The steel / plastic material pairing according to claim 6 is particularly preferred, as it has proven to be both reliable and quiet, especially in the pre-closing position.

[0012] In the further preferred embodiments according to claims 8 and 9, an opening tendency in the above sense is provided for one of the locking positions of the latch, in particular for the main locking position, so that a secondary locking pawl must be used in this respect. The combination of the proposed solution for the preliminary locking position with an opening tendency for the main locking position provides a particularly good compromise between high operational reliability and low actuating forces.

[0013] The proposed solution makes it particularly easy for both the pre-locking locking surface and the main locking locking surface to each form a section of the narrow side of a disc-shaped body of the lock latch. The result is a particularly compact and, at the same time, easy-to-manufacture design for the motor vehicle lock (claim 10).

[0014] The invention will now be explained in more detail with reference to a drawing that illustrates only one embodiment. The drawing shows Fig. 1 shows the essential components of a proposed motor vehicle lock in a perspective view, Fig. 2 shows the motor vehicle lock in a top view a) with the latch in the pre-lock position and b) with the latch in the main locking position, Fig. 3 shows the forces acting on the locking pawl in the Fig. 2a ) situation shown, and Fig. 4 the forces acting on the pawl in the in Fig. 2b ) situation shown.

[0015] It should be noted in advance that the drawing only shows those components of the proposed motor vehicle lock 1 that are necessary for explaining the teaching.

[0016] The illustrated motor vehicle lock can be applied to virtually all locking elements of a motor vehicle. Reference may be made in this respect to the introductory part of the description. Here, and preferably, the locking element is a motor vehicle door or a motor vehicle hatch.

[0017] The proposed vehicle lock 1 is equipped with a lock latch 2 that pivots about a pivot axis 2a and, in the assembled state, interacts with a locking element 3, here and preferably with a locking bolt, a locking pin, or the like. The vehicle lock may be located on the locking element, while the locking element 3 is arranged on the vehicle body. The reverse arrangement is also possible. The vehicle lock 1 further comprises a pivotable primary locking pawl 4, which interacts with the lock latch 2 in a manner to be explained later.

[0018] The lock latch 2 has moved from an open position (not shown) to a pre-closed position ( Fig. 1 , Fig. 2a )) and into a main closing position following the preliminary closing position ( Fig. 2b )) can be brought into position and locked in the respective closed position by the primary locking pawl 4. In the illustration according to Fig. 2 The open position results from a pivoting of the lock latch 2 from the in Fig. 2a ) shown position, proceeding clockwise. Starting from the open position, the main closing position is therefore, in the above sense, downstream of the pre-closing position.

[0019] The term "lockable" in this context means quite generally that the latch 2 is held in the respective closed position by the primary locking pawl 4 in some way. The term "locking" is to be interpreted broadly and does not necessarily include a detent engagement or the like.

[0020] The latch 2 has a pre-locking locking surface 5 with which the primary locking pawl 4 engages when the latch 2 is in the pre-locking position. The latch 2 also has a main locking locking surface 6 with which the primary locking pawl 4 engages when the latch 2 is in the main locking position. The term "locking engagement" and the term "lockable" are to be interpreted broadly in the above sense.

[0021] The primary locking latch 4 accordingly has a pre-locking counter-locking surface 7 and a main locking counter-locking surface 8, which interact with the corresponding locking locking surfaces 5, 6 of the latch 2. The locking of the latch 2 in the respective closed position thus occurs via the interaction between the respective locking surfaces 5, 6 and counter-locking surfaces 7, 8, which are in locking contact with each other at a respective locking engagement point 11, 12.

[0022] The proposed method of locking the latch 2 is implemented in the exemplary embodiment for the pre-locked position of the latch 2. All related details are applicable accordingly to a possible implementation of the proposed locking method for the latch 2 in the main locked position.

[0023] The following explanation of the proposed locking mechanism of the latch 2 in the pre-locked position assumes that an opening torque 9, i.e., a torque in the opening direction of the latch 2, acts on the latch 2. This opening torque 9 results from a force exerted by the locking element 3 on the latch 2 and, if applicable, on an opening spring of the latch 2. Since the locking element is regularly associated with locking element seals that generate a door seal counter-pressure in both the pre-locked and fully locked positions, a corresponding opening torque 9 is to be expected in both positions. However, the opening torque 9 is lower in the pre-locked position than in the fully locked position due to the reduced compression of the locking element seals.

[0024] It is essential that the opening torque 9, here with the latch 2 in the pre-locked position, has at least two effects via the locking engagement: On the one hand, the opening torque 9 causes a lifting torque 10, i.e., a torque in the direction of lifting the primary locking pawl 4, at the primary locking pawl 4, since the normal N of the locking surface, here the pre-locking surface 5, and thus the associated normal force FN at the locking engagement point 11 between the latch 2 and the primary locking pawl 4, passes along the pivot axis 4a of the primary locking pawl 4. This is best illustrated in the diagram. Fig. 3 to be taken.

[0025] On the other hand, the opening torque 9, via the locking engagement, generates a static friction force FH at the locking engagement point 11 between the latch 2 and the primary locking pawl 4, such that the latch 2 and the primary locking pawl 4 form a self-locking mechanism via the locking engagement. The lifting torque 10 and the static friction force FH are thus related to each other in such a way that the opening torque 9, regardless of its magnitude, cannot generate any lifting movement of the primary locking pawl 4.

[0026] In this sense, for the sake of completeness, it should be noted that the proposed self-locking mechanism between the latch 2 and the primary locking pawl 4 is independent of the extent to which the primary locking pawl 4 is pre-tensioned towards the latch 2 or what friction prevails in the pivot bearing associated with the pivot axis 4a of the primary locking pawl.

[0027] Here, and preferably, in at least one closed position, here in the pre-closing position, the angle of inclination φ of the lock latch 2 between the normal N at the locking engagement point 11 and the radial beam R passing through the locking engagement point 11 and referred to the pivot axis 4a of the primary locking pawl 4 is smaller than the static friction angle p, preferably smaller than 90° of the static friction angle ρ.

[0028] The angle of static friction ρ, when two surfaces are engaged at a point of contact, is, according to the expert understanding applicable here, the maximum angle with respect to the common surface normal of the two surfaces at the point of contact, at which a force can act from one surface onto the other without overcoming the static friction at the point of contact. According to a more general definition, the angle of static friction is also described by the "static friction cone," which is also well-known in the field.

[0029] In the self-locking configuration presented here, the static friction force FH ensures that the resulting force F res, acting from the latch 2 on the primary locking pawl 4 at the locking engagement point 11, always passes through the pivot axis 4a of the primary locking pawl 4. This means that the angle of attack φ mentioned above, between the normal N at the locking engagement point 11 and the radial ray R passing through the locking engagement point 11 and referenced to the pivot axis 4a of the primary locking pawl 4, is smaller than the static friction angle ρ at the locking engagement point 11. As soon as this condition is no longer met, the static friction force FH reaches its maximum value F Hmax, which, as is known, corresponds to the product of the normal force FN and the coefficient of static friction µ, which will be explained later. This would mean that the resulting force F res no longer passes through the pivot axis 4a of the primary locking pawl 4.What is interesting here is the fact that the direction of the resulting force Fres can be easily adjusted by the design of the respective locking surface 5, 6 or the respective counter-locking surface 7, 8. In this respect, the proposed solution can be adapted to the respective boundary conditions using simple manufacturing techniques.

[0030] Particularly high operational reliability is achieved by ensuring that the angle of attack φ is a certain distance from the angle of static friction ρ. In a particularly preferred embodiment, the angle of attack φ is less than 90% of the angle of static friction ρ.

[0031] The static friction angle ρ can be easily calculated. This calculation is based on the fact that in at least one closed position, here the pre-locked position, the lock latch 2 has a coefficient of static friction µ at the locking engagement point 11, where the static friction angle ρ is defined by the formula ρ = arctan(µ).

[0032] In a particularly preferred embodiment, the angle of attack φ is in a range between 1° and 4°, preferably at about 3°.

[0033] In principle, it can be provided that in at least one locking position, here in the pre-locking position, the locking engagement between the locking latch 2 and the primary locking pawl 4 at the locking engagement point 11 has the material pairing steel / steel with a coefficient of static friction µ in a range between 0.45 and 0.8.

[0034] For the pre-lock position, it is preferably intended that the locking engagement between the latch 2 and the primary locking pawl 4 at the locking engagement point 11 has a steel / plastic material pairing with a coefficient of static friction µ in the range of 0.32 to 0.45. This allows the actuating force required to open the vehicle lock to be further reduced, while maintaining a high level of operational reliability with regard to locking the latch 2 in its pre-lock position, provided the above condition is met. It is also conceivable, in principle, that the locking engagement between the latch 2 and the primary locking pawl 4 at the locking engagement point 11 has a plastic / plastic material pairing.

[0035] Any plastic component in the respective material pairing may be due to the encasing of the lock latch and / or the locking bolt. In this case, the encasing provides the respective locking surface or counter-locking surface.

[0036] The proposed solution can, in principle, also be applied to the main locking position of the latch 2. Here, and preferably, it is provided that the locking engagement between the latch 2 and the primary locking pawl is designed with an opening tendency in the main locking position, so that the primary locking pawl 4 can be lifted by the opening torque of the latch 2 via the locking engagement, specifically at the locking engagement point 12.Specifically, in at least one closed position, here in the main closed position of the latch 2, an opening moment 9 acting on the latch 2, via the locking engagement, generates a lifting moment 10 at the primary locking pawl 4, since the normal N of the locking surface 6 at the locking engagement point 12 between the latch 2 and the primary locking pawl 4 passes along the pivot axis 4a of the primary locking pawl 4, so that the opening moment 9, via the locking engagement, can generate a lifting movement of the primary locking pawl 4. The resulting force Fres acting from the latch 2 on the primary locking pawl 4 at the locking engagement point 12 passes along the pivot axis 4a of the primary locking pawl 4 and exerts a force via the... Fig. 4 The lever arm d shown exerts a lifting moment 10 on the primary locking pawl 4. In contrast to the explanation above regarding the pre-closing position, the static friction force here is designed so that it can be easily overcome by the opening moment 9.

[0037] This is the classic case of a design with an opening tendency, where here, and preferably, a secondary locking pawl 13 pivotable about a pivot axis 13a is provided, which locks the primary locking pawl 4 in at least one closed position, here in the main closed position, of the lock latch 2. The primary locking pawl 4 is therefore unable to perform any lifting movement due to the action of the secondary locking pawl 13.

[0038] It has already been pointed out that the combination of the proposed solution for the preliminary closing position with an opening tendency for the main closing position provides a particularly good compromise between high operational reliability and low operating forces. This applies especially in the case where both the primary locking pawl 4 and the secondary locking pawl 13 are to be lifted by a drive motor 17, as in Fig. 1 As indicated, the drive motor 17 is preferably coupled via a drive cable 18 to a drive lever (not shown), the actuation of which can cause both the primary locking pawl 4 to be released for the pre-locked position and the secondary locking pawl 13 to be released for the main locked position. For optimal design and control of the drive motor 17, the design is such that the drive motor 17 must provide a similar, and in particular identical, drive power and / or a similar, and in particular identical, drive torque or drive force for releasing the primary locking pawl 4 as for releasing the secondary locking pawl 13.

[0039] An interesting aspect of the proposed solution is that it is readily possible to implement both the pre-locking and the main locking positions of the latch 2 with one and the same primary locking pawl 4, which can be brought into direct locking engagement with the latch 2. Here, and preferably, the latch 2 has a disc-shaped body 14, wherein the pre-locking locking surface 5 and the main locking locking surface 6 each form a section of the narrow side 15 of the disc-shaped body of the latch 2. As mentioned above and as in Fig. 1 As shown, the lock latch 2 is provided for with a casing 16 which can form at least the pre-locking locking surface 5. This results in the aforementioned steel / plastic material pairing at the locking engagement point 11.

[0040] It should also be noted that in the above considerations, all effects resulting from elastic or plastic deformations at the locking latch 2, the primary locking pawl 4 and the secondary locking pawl 13 have been neglected for the sake of a simplified presentation.

[0041] In conclusion, the proposed solution reduces the operating force required to open the vehicle lock 1 without compromising operational safety and without requiring complex design measures.

Claims

1. Motor vehicle lock with a pivotable lock latch (2), which, in the mounted state, interacts with a locking part (3), in particular a lock striker, and with a pivotable primary pawl (4), wherein the lock latch (2) can be brought from an open position into a pre-locking position and into a main locking position downstream of the pre-locking position and can be blocked in the respective locking position by the primary pawl (4), wherein the lock latch (2) has a pre-locking blocking surface (5), with which the primary pawl (4) is in blocking engagement when the lock latch (2) is in the pre-locking position, wherein the lock latch (2) has a main locking blocking surface (6), with which the primary pawl (4) is in blocking engagement when the lock latch (2) is in the main locking position, and wherein the primary pawl (4) can be lifted out of engagement with the respective locking blocking surface (5, 6) of the lock latch (2), characterized in that, in at least one locking position, in particular in the pre-locking position, of the lock latch (2), by way of the blocking engagement, an opening moment acting on the lock latch (2), on the one hand, generates a lifting-out moment (10) on the primary pawl (4), since the normal (N) of the locking blocking surface at the blocking engagement point (11) between the lock latch (2) and primary pawl (4) runs past the pivot axis (4a) of the primary pawl (4), and, on the other hand, generates a static friction force (FH) at the blocking engagement point (11) between the lock latch (2) and the primary pawl (4) in such a manner that the lock latch (2) and the primary pawl (4) form, by way of the blocking engagement, a self-locking mechanism for a reliable retaining action.

2. Motor vehicle lock according to Claim 1, characterized in that, in at least one locking position, in particular in the pre-locking position, of the lock latch (2), the angle of inclination (φ) between the normal (N) at the blocking engagement point (11) and the radial line (R), which is related to the pivot axis (4a) of the primary pawl (4) and extends through the blocking engagement point (11), is smaller than the static friction angle (ρ), preferably smaller than 90% of the static friction angle (ρ).

3. Motor vehicle lock according to Claim 1 or 2, characterized in that the angle of inclination (φ) is in a range of between 1° and 4°, preferably is approximately 3°.

4. Motor vehicle lock according to one of the preceding claims, characterized in that, in at least one locking position, in particular in the pre-locking position, of the lock latch (2), a coefficient of static friction (µ) acts at the blocking engagement point (11) and in that the static friction angle (ρ) is defined by the rule ρ=arctan(µ).

5. Motor vehicle lock according to one of the preceding claims, characterized in that, in at least one locking position, in particular in the pre-locking position, of the lock latch (2), the blocking engagement between the lock latch (2) and the primary pawl (4) has, at the blocking engagement point (11), the material pairing of steel / steel with a coefficient of static friction (µ) in a range from 0.45 to 0.8.

6. Motor vehicle lock according to one of the preceding claims, characterized in that, in at least one locking position, in particular in the pre-locking position, of the lock latch (2), the blocking engagement between the lock latch (2) and the primary pawl (4) has, at the blocking engagement point (11), the material pairing of steel / plastic with a coefficient of static friction (µ) in a range from 0.32 to 0.45.

7. Motor vehicle lock according to one of the preceding claims, characterized in that, in at least one locking position, in particular in the pre-locking position, of the lock latch (2), the blocking engagement between the lock latch (2) and the primary pawl (4) has, at the blocking engagement point (11), the material pairing of plastic / plastic.

8. Motor vehicle lock according to one of the preceding claims, characterized in that, in at least one locking position, in particular in the main locking position, of the lock latch (2), by way of the blocking engagement, an opening moment (9) acting on the lock latch (2) generates a lifting-out moment (10) on the primary pawl (4), since the normal (N) of the locking blocking surface (5) at the blocking engagement point (12) between the lock latch (2) and primary pawl (4) runs past the pivot axis (4a) of the primary pawl (4), so that a lifting-out movement of the primary pawl (4) can be generated by the opening moment (9) by way of the blocking engagement.

9. Motor vehicle lock according to Claim 8, characterized in that provision is made for a secondary pawl (13), which, in at least one locking position, in particular in the main locking position, of the lock latch (2), blocks the primary pawl (4).

10. Motor vehicle lock according to one of the preceding claims, characterized in that the lock latch (2) has a disc-like body and in that the pre-locking blocking surface (5) and the main locking blocking surface (6) each form a portion of the narrow side (15) of the disc-like body.