Abstract:
A door lock ( 10 ) having an opening aid ( 26 ) has a rotatable lock latch ( 12 ), a detent pawl ( 18 ) arresting the latter in the latching position, and a driven driving pin ( 44 ) which opens the detent pawl ( 18 ) and can be blocked against a stop ( 50 ). The previously customary solution of providing the stop ( 50 ) on the detent pawl ( 18 ) restricts the structural design. In order to obtain more scope in the arrangement of the parts, it is proposed to arrange the stop ( 50 ) on a separate blocking lever ( 48 ) which can be carried along into its blocking position by the detent pawl ( 18 ) during the opening.

Description:
FIELD AND BACKGROUND OF THE INVENTION 
     The invention is concerned with a door lock, in particular for doors, tailgates or hoods of motor vehicles, having a lock latch which can be pivoted between a position releasing a locking peg and a position locking the latter, a detent pawl which can be moved between a locking position arresting the lock latch and a position releasing the lock latch, and a motor-driven, circulating driving pin which, when the drive is switched on, carries the detent pawl along in its path into its position releasing the lock latch and then runs against a stop which retains the detent pawl, which is situated in its position releasing the lock latch, in a position which blocks the driving pin. 
     A door lock of this type, as is described, for example; in DE 195 05 779 Al, offers the possibility of switching off the electric driving motor, after the lock latch is released, by monitoring the current consumption of the motor if the driving pin runs against the stop and the current consumption rises as a consequence of the blocked motor. An electronically monitored switching-off means of this type operates more reliably than microswitches which are susceptible to faults. 
     In the case of the door lock described in DE 195 05 779 Al, the stop is provided directly on the detent pawl. Although this solution manages with relatively few parts, there are, limitations in this design, in the spatial arrangement which, under some circumstances, make adaptation to a predetermined constructional space more difficult. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a door lock having an opening aid, said lock permitting a more flexible spatial design. 
     According to the invention, the object is achieved by a door lock of the type described at the beginning, in which the stop is arranged on a blocking lever which is mounted separately from the detent pawl and can be carried along into its blocking position by the detent pawl as it is being shifted into the position releasing the lock latch. 
     The solution according to the invention offers the advantage that a more flexible spatial arrangement of the individual components is possible on account of the separately mounted blocking lever and the simplified detent pawl. As a result, adaptation of the door lock to particular spatial conditions and limitations in constructional space, as can frequently be encountered precisely in the automobile sector, is considerably simplified. In addition, there is the possibility, by varying the center of pressure, of providing a transmission ratio between the detent pawl and the blocking lever which can be used to influence the interaction between the blocking lever, the running-on driving pin and the detent pawl in order to reduce the forces which occur. 
     In a preferred embodiment of the invention, provision is made for the driving motor to drive a driving element which can be rotated counter to the force of a spring in a certain angular range relative to a driving disk which is arranged on the same rotational axis and on which the driving pin is arranged eccentrically. 
     The relative rotatability between the driving element and driving disk counter to the action of the spring avoids under all circumstances, when the electric driving motor has a defect, blocking of the detent pawl which could result in the affected lock no longer being able to open or no longer being able to close. Depending on the position in which the driving pin stops, it is moved by the prestressed spring into a position in which the detent pawl can be moved freely, or in the case of manual emergency opening, for example, the detent pawl can press aside the driving pin, lying in the way, counter to the force of the spring. 
     In a further, preferred refinement, provision is made for a compression spring to be arranged in a spring channel, which is open on one side, on the driving element or the driving disk and to be supported against a stop on the respective other component. Such an arrangement of the compression spring can be fitted easily, particularly low manufacturing costs arising if the driving element and the driving disk are manufactured from plastic and the spring channel and the stop are formed integrally on the respective component. Under some circumstances, the driving pin may also be manufactured from plastic, but at higher loads a driving pin made of metal or a pin which is provided with a metal coating in the region of the contact surface with the detent pawl and the stop is advantageous. Prestressing of the spring may be expedient, also for improving the grip of the spring in the spring channel. 
     Furthermore, a second stop is preferably provided which interacts with the rear wall of the spring channel and limits the relative rotatability between the driving element and the driving disk counter to the prestressing direction of the compression spring. This second stop ensures that undefined relative positions which might be disadvantageous for the functioning are unable to occur between the driving element and the driving disk. 
     It has proven expedient for the spring channel, in a simple design, to extend over an angular range of approximately 90° and to be limited by two lateral, circular-arc-shaped walls. The angular range of 90° of the extent of the spring channel allows prestressing of the compression spring situated in it by approximately 45°, an angular range which has proven particularly expedient in order to avoid malfunctions. 
     In order to improve the functioning capability of the door lock, it is of advantage for the lock latch to be prestressed by a spring in the direction of its open position and/or for the detent pawl to be prestressed by a spring in the direction of its position arresting the lock latch. While the lock latch can be moved during the closing of the tailgate of the vehicle, for example, into its closed position counter to the force of the restoring spring by the locking peg, the detent pawl is moved counter to the force of its restoring spring into its position releasing the lock latch. In the closed position of the lock latch, the latter is supported against a latching means on the detent pawl under the load of its prestressed spring, while when the lock latch is opened, the detent pawl is supported against a correspondingly shaped stop on the lock latch. 
     A particularly simple embodiment makes provision for a single spring between the lock latch and the detent pawl to prestress both elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the following, an exemplary embodiment of the invention is explored in greater detail with reference to the attache the figures of the drawings, in which: 
     FIG. 1 shows a schematic functional diagram of a door lock in the closed inoperative position; 
     FIG. 2 shows the door lock according to FIG. 1 at the beginning of the opening procedure; 
     FIG. 3 shows the door lock according to FIG. 1 with the opening procedure in progress; 
     FIG. 4 shows the door lock shortly after the release of the lock latch; 
     FIG. 5 shows the door lock according to FIG. 1 after the opening procedure is finished and before the drive is switched off;, and 
     FIG. 6 shows the door lock according to FIG. 1 in the open inoperative position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 schematically illustrates a door lock  10  as is used, for example in the motor-vehicle sector, for doors, tailgates or hoods. The door lock  10  has a lock latch  12  which is designed as a rotary latch and arrests a locking peg (not shown), which is arranged on the bodywork, in its closed position. In this arrested position, the lock latch  12  is latched with a latching lug  14  against a catch  16  on a detent pawl  18  which is mounted pivotably about a rotational axis  20 . Provided between the lock latch  12  and the detent pawl  18  is a prestressed tension spring  22  which prestresses the lock latch  12 , in the direction of its open position, against the catch  16  and prestresses the detent pawl  18  against a pressure flank  24  on the lock latch  12  in order to assist the arresting of the lock latch  12 . The detent pawl  18  and the lock latch  12  are illustrated in a simplified manner, by leaving out, for example, a possible prelatching position between the lock latch  12  and the detent pawl  18 , for the purpose of improving clarity. 
     In order to be able to open the lock automatically, the door lock  10  furthermore has an opening aid  26 . This has a driving element  28  which is driven by an electric driving motor ( 101 ) which engages, for example via a worm  100 , in an external toothing  30 , which is formed as a worm wheel, on the driving element  28 . The driving element is mounted rotatably about a rotational axis  32  on which a driving disk  34  is furthermore mounted rotatably. The driving disk  34  can be rotated relative to the driving element  28 , the relative rotation between these two elements taking place counter to the force of a compression spring  36 . 
     The compression spring  36  is arranged in a spring channel  38  which is open on one side and, as regards the viewing direction of FIG. 1, is formed on the lower side of the driving disk  34 . The spring channel  38  extends over an angular range of approximately 90° and is formed by two lateral quarter-circle-shaped walls  40  and a rear wall  42 . 
     Furthermore, a driving pin  44  is provided on the driving disk  34 , said pin transmitting the opening forces to the detent pawl  18 , which will be examined further later on. 
     The driving element  28  acts on the free end of the compression spring  36  via a spring stop  46 , as a result of which the required torques can be transmitted to the driving disk  34 . A second stop  47  on the driving element  28  limits the relative rotatability between the driving element  28  and the driving disk  34  counter to the driving direction so as to avoid undefined relative positions between these two elements. 
     The door lock  10  furthermore has a pivotably mounted blocking lever  48  which has a stop  50  on a first lever arm  52  and a second lever arm  53  which interacts with the detent pawl  18 . 
     As already mentioned, the door lock  10  according to FIG. 1 is in the locked inoperative position, the driving pin  44  lying outside the engagement region of the detent pawl  18  and the blocking lever  48 . The compression spring  36  is relaxed to the maximum, although it may be in a prestressed state. 
     If the electric driving motor is now switched on, the rotating driving element  28  carries along the driving disk  34  via the spring stop  46 . Since said driving disk initially runs without resistance, the compression spring  36  is initially not compressed until the driving pin  44  reaches a lever arm  54  of the detent pawl  18 , in accordance with the illustration according to FIG.  2 . Since the tension spring  22  is under prestressing, the more weakly dimensioned compression spring  36  is initially compressed in the spring channel  38  (see FIG.  3 ), since the driving element  28  is rotated further in spite of the driving disk  34  being blocked by the lever arm  54 . If the spring  36  is prestressed to the maximum, the driving disk  34  is again carried along, in which case the detent pawl  18  moves, under further prestressing of the tension spring  22 , outward into its position releasing the lock latch  12  (see FIG.  4 ). 
     As soon as the catch  16  releases the latching lug  14  of the lock latch  12 , the latter snaps under the action of the tension spring  22  into its open position in which it releases the locking peg. The door, hood or tailgate can be opened. In this case, the detent pawl  18  is supported in the open state against the pressure flank  24  of the lock latch  12 , resulting in a stable opening state in spite of the more powerfully prestressed tension spring  22 . 
     Since the electric driving motor is still activated, the driving pin  44  moves beyond the position shown in FIG. 4, the compression spring  36  being immediately relaxed if the driving pin  44  has passed out of the engagement region of the lever arm  54  (see FIG.  5 ). The lever arm  18  of the opened detent pawl  18  also carries along the second lever arm  53  of the blocking lever  48 , as a result of which the first lever arm  52 , with the stops  50 , is pivoted into the circulating path of the driving pin. With the compression spring  36  initially relaxed (see FIG.  5 ), in spite of the driving pin  44  having already been blocked by the stop  50 , the driving element continues to run, with compression of the compression spring  36  over an angular range of approximately 45° until it is also blocked after exhausting the spring travel. The blocking causes a rise in the current consumption of the electric driving motor, which rise is detected electronically and causes the switching-off of the driving motor. The door lock is now situated in the open inoperative position, shown in FIG. 6, in which the tension spring  22  and the compression spring  36  are prestressed to the maximum. 
     If the corresponding door, hood or tailgate is now closed, the lock latch  12  is moved by the locking peg into the closed position shown in FIG. 1, the latching lug  14  again latching in the catch  16  of the detent pawl  18 . The lever arm  54  thereby releases the locking lever  48  which moves clockwise, in the sense of the illustration, under the action of the compression spring  36  until the driving pin  44  is released. The driving disk  34  now moves counterclockwise, in the sense of the illustration, under the action of the relaxing compression spring  36 , with the result that the door lock  10  again assumes a closed inoperative position. 
     The relative mobility between the driving disk  34  and the driving element  28  ensures that even in the event of the electric driving motor breaking down, the driving pin  44  cannot block the lever arm  54  of the detent pawl  18  or the first lever arm  52  of the blocking lever  48 . In the event of the driving motor failing, the relative rotational range of 45° is sufficient in order to force back the driving pin, with the aid of an emergency opening device (not illustrated), to open the lock in the clockwise direction according to the illustration, if it is situated in the region of the first lever arm  52  of the blocking lever  48 . If the motor breaks down with the pin  44  positioned in the region of the lever arm  54 , the force of the tension spring  22  is sufficient for closing the detent pawl  18  even counter to the force of the compression spring  36 . 
     In addition to the emergency opening device which has already been mentioned and the prelatching position which is generally provided between the lock latch and the detent pawl, the door lock  10  can have further functions, for example an automatic pulling-tight aid for the door, which can be realized in a customary manner. Use of the door lock outside the motor-vehicle sector as well is readily conceivable.