MOTOR-VEHICLE LOCK

Abstract

A method and a device for operating an opening drive for a motor-vehicle lock, in particular motor-vehicle door lock. Also provided is a locking mechanism which consists substantially of a rotary latch and a pawl. Further, a sensor associated with the rotary latch is provided, as well as a drive unit that indirectly or directly acts upon the pawl, the drive unit being controlled according to signals of the sensor. According to the invention, the sensor produces a signal only once the rotary latch can be freely opened.

Claims

1. A method for operating an opening drive for a motor-vehicle lock, wherein the motor vehicle lock comprises a locking mechanism including a rotary latch and a pawl, a sensor associated with the rotary latch, and a drive unit acting indirectly or directly on the pawl, the method comprising controlling the drive unit as a function of a signals from the sensor, wherein the sensor only generates the signal as soon as the rotary latch is in a position to be opened freely.

2. The method according to claim 1, wherein free opening of the rotary latch is accompanied by the sensor reporting the opening of the rotary latch and, at the same time, an electrical power acting on the drive unit falling below a predetermined threshold.

3. The method according to claim 2, wherein the predetermined threshold of the electric power corresponds to a threshold of electric current absorbed by the drive unit as a function of time.

4. The method according to claim 1, wherein free opening of the rotary latch is achieved when the pawl enters an overtravel area.

5. The method according to claim 4, wherein the drive unit loads and/or reverses and/or decelerates the pawl in the overtravel area without load of sufficient amount such that the pawl is lifted from the rotary latch.

6. The method according to claim 4, wherein the entry of the pawl into the overtravel area correlates with a threshold to be undershot of absorbed electric current or electric power.

7. A device for operating an opening drive for a motor-vehicle lock for performing the method according to claim 1, the device comprising: a locking mechanism including a rotary latch and a pawl, a sensor associated with the rotary latch, and a drive unit acting indirectly or directly on the pawl, wherein the drive unit is configured to control the pawl as a function of a signals from the sensor, wherein the sensor only generates the signal as soon as the rotary latch is in a position to be opened freely.

8. The device according to claim 7, further comprising a control unit configured to evaluate the signals of the sensor and to evaluate the electrical power received from the drive unit.

9. The device according to claim 8, wherein the control unit evaluates the electric current picked up by the drive unit in a time-resolved manner.

10. The device according to claim 7, wherein the control unit links the time-resolved electric current to the signal of the sensor.

11. The method according to claim 1, wherein in response to the signal the drive unit is decelerated and/or reversed.

12. The method according to claim 11, further comprising an end stop in the overtravel area, and drive unit is decelerated and/or reversed prior to impacting the end stop.

13. The method according to claim 6, wherein upon undershot the drive unit is decelerated and/or reversed.

Description

[0024] In the following, the invention is explained in more detail with the aid of a drawing showing only an exemplary embodiment; in the figures:

[0025] FIG. 1 shows a device according to the invention for operating an opening drive for a motor-vehicle lock schematically, and

[0026] FIG. 2 shows a time diagram of the actuation of the sensor and the current drawn by the drive unit.

[0027] In the figures, a device for operating an opening drive for a motor-vehicle lock is represented. The motor-vehicle door lock is not restrictively a motor-vehicle door lock. The motor-vehicle lock or motor-vehicle door lock has a locking mechanism 1, 2 consisting substantially of rotary latch 1 and pawl 2. In addition, a drive unit 3, 4, 5, 6 is implemented which acts directly or indirectly on the pawl 2.

[0028] The position of the rotary latch 1 can be sensed using a sensor 7. The sensor 7 is connected to a common control unit 8, as is the drive unit 3, 4, 5, 6 or an electric motor 3 as part of the drive unit 3, 4, 5, 6.

[0029] The drive unit 3, 4, 5, 6 has the electric motor 3 mentioned earlier, which carries a worm 4 on its drive shaft. The worm 4 meshes with outer peripheral teeth of a worm wheel 5. The worm wheel 5 is equipped with a cam 6 which, according to the exemplary embodiment, is layered and configured to directly act on the pawl 2. In addition, an end stop 9 for the drive unit 3, 4, 5, 6 is also implemented, which in principle and according to the invention is also dispensable. The end stop 9 can be equipped with rubber elements or a buffer not expressly shown in order to avoid a hard stop of the worm wheel 5 interacting therewith at the end of the actuating travel of the drive unit 3, 4, 5, 6 and to minimize any acoustic noise associated therewith.

[0030] To open the locking mechanism 1, 2 shown in the closed state in FIG. 1, the electric motor drive unit 3, 4, 5, 6 is actuated with the aid of the control unit 6 in such a manner that the cam 6 carried by the worm wheel 5 performs a clockwise movement about an axis of the worm wheel 5 shown in FIG. 1. Since the cam 6 is designed to be eccentric, the clockwise movement of the worm wheel 5 causes the pawl 2 to increasingly pivot about its axis in a counterclockwise direction, as is also indicated in FIG. 1.

[0031] As a result, the pawl 2 is increasingly lifted from its engagement with the rotary latch 1. Since the rotary latch 1 is acted upon by a spring not shown or any door rubber forces of an associated motor-vehicle door, the lifting of the pawl 2 from its engagement with the rotary latch 1 causes the rotary latch 1 to pivot open about its axis in the clockwise direction also indicated in FIG. 1. This releases a previously captured locking bolt 10 and also allows a corresponding motor-vehicle door to be opened.

[0032] The rotary latch 1 performs a free opening as soon as the pawl 2 can no longer interact with the rotary latch 1. According to the exemplary embodiment, this is the case when a detent 1a, 1b or both detents 1a, 1b of the rotary latch 1 have safely passed a detent tooth 2a of the pawl 2. For this purpose, the pawl 2 is moved by the drive unit 3, 4, 5, 6 into an overtravel area, in which the pawl 2 is loaded almost load-free by the drive unit 3, 4, 5, 6. After completing the overtravel area, the drive unit 3, 4, 5, 6 drives against the end stop 9 or can drive against it, as will be explained in more detail below.

[0033] FIG. 2 now shows the opening process with the aid of diagrams. In the final analysis, two different curves can be seen: on the one hand, a dash-dotted curve for the time-resolved signal of the sensor 7 interrogating the rotary latch 1 and, on the other hand, a solid curve representing the time-resolved signal of the current I picked up by the drive unit 3, 4, 5, 6 or the electric motor 3 there.

[0034] At the start of the opening process (t=t.sub.0) and even before, the sensor 7 outputs the signal 1, which corresponds to the fact that the rotary latch 1 is closed. As soon as, starting from the time t=t.sub.0, the drive unit 3, 4, 5, 6 and in particular the electric motor 3 are energized, the current I drawn through and drawn by the electric motor 3 increases to a value Imax. This can be attributed to the fact that breakaway torques of the drive unit 3, 4, 5, 6 and any static friction must be overcome to start the opening process.

[0035] Subsequently, the electric current I consumed by the electric motor 3 and thus the drive unit 3, 4, 5, 6 drops exponentially for the most part over time t. According to the exemplary embodiment and in accordance with the invention, the design is now such that the sensor 7 performs a signal change from 1 to 0 in the sense of an opening of the rotary latch 1 when the pawl 2 passes into an area t.sub.overtravel indicated in FIG. 2. Reaching this area t.sub.overtravel is accompanied by the fact that the current I drawn by the electric motor 3 falls below a predetermined threshold I.sub.? or falls below this threshold I.sub.?.

[0036] The sensor 7 can be positioned and designed in such a manner that it only signals the opening of the rotary latch 1 when the pawl 2 enters the overtravel area t.sub.overtravel. According to the exemplary embodiment, moreover, the signal of the sensor 7 and also the current I picked up by the electric motor 3 can be linked together in the control unit 8. In any case, the free opening of the rotary latch 1 is achieved when the pawl 2 enters the overtravel area t.sub.overtravel. In this overtravel area, the drive unit 3, 4, 5, 6 can apply almost no load to the pawl 2.

[0037] According to the invention, the entry of the pawl 2 into the overtravel area t.sub.overtravel now correlates with the fact that the threshold I.sub.? of the absorbed electrical power or the absorbed electrical current I on the part of the electric motor 3 is undershot. As a result, when the pawl 2 enters the overtravel area t.sub.overtravel, the drive unit 3, 4, 5, 6 can be reversed and/or decelerated. As a result, according to the invention, there is no renewed current increase as shown in FIG. 2 following the overtravel area t.sub.overtravel, which corresponds to the fact that the drive unit 3, 4, 5, 6 has moved against the end stop 9. This means that, according to the invention, the diagram in FIG. 2 ends practically before the current rises again at the end stop or this current rise can be significantly reduced because the drive unit 3, 4, 5, 6 has been decelerated and/or reversed beforehand, i.e. before reaching the end stop 9.

[0038] As a result, the increase in current I following the overtravel area t.sub.overtravel is alternatively represented as dashed in FIG. 2 and achieved according to the invention. It should be noted that, depending on the design of the control unit 8 and the drive unit 3, 4, 5, 6, the dashed area is not necessarily reached or does not have to be reached, so that the end stop 9as already describedis basically dispensable. Either way, with the aid of the control unit 8 and the special positioning of the sensor 7 or the evaluation of the signal from the sensor 7 in connection with the current I drawn by the drive unit 3, 4, 5, 6, the mechanical loads on the drive unit 3, 4, 5, 6 can be significantly reduced compared with the previous prior art. This also has a positive effect on the noise behavior. These are the main advantages.

TABLE-US-00001 List of reference numbers 1 rotary latch 1a detent 1b detent 2a detent tooth 2 pawl 3 electric motor 4 worm 5 worm wheel 6 cams 3, 4, 5, 6 drive unit 7 sensor 8 control unit 9 end stop t time I current I.sub.? threshold I.sub.max value t.sub.overtravel overtravel area