Abstract:
A lock with a rotary latch and with a pawl, wherein the pawl can be moved from a blocking position, in which it holds the rotary latch in a closed position, into a release position, in which it allows the rotary latch to rotate into an open position, by the winding of a traction element onto a winding body. A flexible belt, which is wound in spiral fashion around the winding body, can be used as the traction element.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority of DE 10 2010 017 537.4, filed Jun. 23, 2010, and DE 10 2011 001 391.1, filed Mar. 18, 2011, the priority of these applications is hereby claimed and these applications are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The invention pertains to a lock with a rotary latch and with a pawl, wherein the pawl can be shifted from a blocking position, in which it holds the rotary latch in a closed position, into a release position, in which it allows the rotary latch to rotate into an open position, by the winding of a traction element onto a winding body. 
         [0003]    A lock of this type is previously known from DE 10 2005 052 665 A1. The rotary latch lock described there has a lock base plate, which comprises a catch slot for a locking bar. A rotary latch comprising catch jaws for the locking bar is supported on one side of the catch slot; this latch can be shifted against the restoring force of a rotary latch spring into a closed position, in which the locking bar caught in the rotary latch jaws is held captured. The lock base plate supports a pawl, a latching stage of which, when in a blocking position, lies in front of a latching shoulder of the rotary latch and thus prevents the rotary latch from rotating from its closed position into its open position. A traction cable acts on an actuating arm of the pawl; the cable can be wound up onto a winding body formed by a motor shaft to shift the pawl from its blocking position into its release position, which allows the rotary latch to pivot from its closed position into its open position. 
       SUMMARY OF THE INVENTION 
       [0004]    The invention is based on improving such a lock. 
         [0005]    The goal is accomplished by the invention, wherein it is provided first and essentially that the traction element is a flexible belt. This belt is wound in spiral fashion around the winding body. Individual turns of the belt can thus rest on top of each other, which means that, as the belt is being wound up, the effective diameter of the coil increases. The belt can be formed as a one-piece unit with the winding body. For this purpose, the belt and the winding body can be injection-molded out of a suitable plastic. The winding body can have an eccentric shape. In this case, the winding body preferably has the shape of an eccentric cam, where surface sections on which the belt can rest are different distances away from the rotational axis of the winding body depending on their point on the circumference. The length of the belt is calculated in such a way that, in the actuation phase, during which the greatest forces must be applied to the pawl, the working point of the belt is the minimum distance away from the takeoff shaft, so that the electric motor preferably used to drive the winding body can exert the maximum torque on the belt during this actuation phase. The belt is elastic preferably in the sense that it is able only to bend, so that it can be wound in spiral fashion around the winding body but is stiff in the direction transverse to that. Because the belt is wound in spiral fashion around the winding body, the force which can be transmitted by the belt to the pawl changes over the course of the movement of the pawl from its blocking position to its release position. The opening drive exerts its greatest tractive force during the phase in which the latching stage is disengaged from the latching shoulder. In a preferred variant, the belt acts on a transmission lever, which, like the rotary latch and the pawl, is supported so that it can rotate around an axis fixed to the base plate. The transmission lever can comprise two arms. The free end of the traction belt acts on one of these two arms, namely, the drive arm, the free end of the belt preferably being designed as a coupling pin, which rests in a coupling opening, such as an opening with a claw-like shape, in the drive arm. A takeoff arm, preferably projecting at a right angle to the drive arm, acts on an actuating arm. This actuating arm is supported rotatably around the same axis as that around which the pawl rotates. The pawl can comprise a driver, on which a stop shoulder of the actuating arm acts to carry the pawl along from the blocking position into the release position, preferably after traveling a certain free distance. It has been found to be favorable with respect to the physics of levers for the takeoff arm of the transmission lever to act on the outermost end of the actuating arm, which, in one variant of the invention, can also be rigidly connected to the pawl. To reduce the opening force, the latching stage and the latching shoulder engage with each other at a positive angle. In another variant, the lock has only one latch, such as a latch with a negative angle. To prevent vibrations from causing the pawl, when in the blocking position, from becoming unlatched by itself, the pawl is held in the blocking position by a blocking element. This blocking element is designed as a blocking cam, which, when in a blocking position, lies in front of a blocking shoulder of the pawl. The blocking cam is preferably a component of the transmission lever and, in a first actuation phase, is pivoted out of its blocking position upon rotation of the winding body. Only then does the takeoff arm of the transmission lever engage with the working end of the actuating arm to shift the actuating arm against the restoring force of a spring over a certain free travel distance until its stop shoulder arrives at the driver of the pawl and shifts the pawl into the release position. In a preferred embodiment, a storage hook is formed on the actuating arm; during the movement into the release position, this hook travels over a storage web, which is assigned to the rotary latch and on the outside wall of which the storage hook rests when the rotary latch moves from its closed position to its open position. This prevents the pawl from moving back into the blocking position, after the belt has been turned back, for example, before the rotary latch has opened completely. The main latching stage or a prelatching stage also assigned to the pawl is thus prevented from arriving in a latching position relative to the latching shoulder of the rotary latch during the course of the opening movement of the rotary latch. 
         [0006]    The pawl is supported rotatably around a rotational axis permanently attached to the housing and has a core made of steel, which forms a prelatching stage and a main latching stage. When the rotary latch moves from its open position to its closed position, a rotary latch spring is put under tension. During the course of the rotational movement, a radially projecting section of the latching shoulder of the rotary latch slides along a ramp-like flank of the pawl, which ends in a prelatching stage formed by the pawl. Once past the prelatching stage, the pawl can pivot into the prelatching position under the action of its rotary latch spring, wherein the prelatching stage comes to rest under the latching shoulder, so that the rotary latch cannot be turned back into the open position. The rotary latch, however, can be turned farther away from the prelatching position toward the closed position, wherein, here again, a radially projecting section of the latching shoulder slides along a control flank of the pawl until the main latching stage of the rotary latch passes under the latching shoulder. Whereas the prelatching stage and the other essential surface sections of the pawl are jacketed with plastic, the main latching stage does not have a jacket of plastic. The steel surface of the main latching stage rests on a steel surface of the latching shoulder of the rotary latch, which otherwise can also be jacketed with plastic. A spring web formed by the plastic jacketing of the pawl rests on the radially outermost section of the latching shoulder to prevent rattling. 
         [0007]    The invention also pertains to a winding body. The winding body can be used quite generally in locks and actuating elements and has the previously described property. It is an injection-molded part of plastic with a winding body, the horizontal section of which extends along an eccentric line around an axis. At the axis, an opening can be provided, which comprises a noncircular cross section, and into which a drive shaft of a drive motor can be inserted. The traction element, which is designed as a flat belt, can be wound around the winding body in the form of spiral turns. At its free end, the belt carries coupling pins, which can engage in coupling openings in an actuating element such as a drive arm. The production of the winding body together with the belt is carried out by the injection-molding process, wherein the belt is preformed into a spiral. In the relaxed state, the flexible belt then extends in such a way that the individual turns of the belt are separated from each other by an air gap. As a result, the motion transmission means consisting of the winding body and the belt can be fabricated very easily. 
         [0008]    The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to descriptive matter in which there are described preferred embodiments of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0009]    In the drawing: 
           [0010]      FIG. 1  shows a top view of the lock of an exemplary embodiment of the lock in the closed position; 
           [0011]      FIG. 2  shows a perspective, partially exploded view of the rotary latch  1 , the pawl  2 , the actuating arm  3 , and the opening gear train  4 ,  5 ,  6 ,  18  in the closed position; 
           [0012]      FIG. 3  shows a diagram according to  FIG. 1 , wherein the transmission lever  6  has been shifted by traction of the belt  4  until it has reached an action position on the actuating arm  3  and has pushed the actuating arm  3  until it has arrived in a driving position on the pawl  2 ; 
           [0013]      FIG. 4  shows the functional position according to  FIG. 3  looking in the direction of the arrow IV in  FIG. 3 ; 
           [0014]      FIG. 5  shows a diagram of a state subsequent to that of  FIG. 3 , wherein the actuating arm  3  of the transmission lever  6  has moved the pawl into its release position, wherein a storage hook  16  has passed over a storage web  17  but the rotary latch  1  has still not pivoted into the open position; 
           [0015]      FIG. 6  shows a diagram of a state subsequent to that of  FIG. 5 , wherein the rotary latch has been pivoted into its open position and the pawl is still in its release position; 
           [0016]      FIG. 7  shows the functional position according to  FIG. 6  looking in the direction of the arrow VII of  FIG. 6 ; 
           [0017]      FIG. 8  shows a diagram of a state subsequent to that of  FIG. 6 , wherein the belt  4  has been brought into a releasing position; 
           [0018]      FIG. 9  shows only the rotary latch  1  in its open position and the pawl  2  in the release position; 
           [0019]      FIG. 10  shows a diagram according to  FIG. 8 , after the rotary latch  1  has been pivoted from its open position into a prelatching position, in which a prelatching stage  10  grips the latching stage  8  from underneath; 
           [0020]      FIG. 11  shows only the rotary latch  1  and the pawl  2  in the prelatching position; 
           [0021]      FIG. 12  shows only the rotary latch and the pawl  2  in the main latching position; 
           [0022]      FIG. 13  shows a cross section through the pawl along cross-sectional line XIII-XIII in  FIG. 12 ; and 
           [0023]      FIG. 14  shows a cross section through the pawl along cross-sectional line XIV-XIV in  FIG. 13 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    The lock shown in the drawings can be used in a motor vehicle as a rear hatch lock or as a door lock. It works together with a locking bar (not shown), which, when the lock is being closed with the rotary latch in the opened position ( FIG. 8 ), is caught in a capture slot  27  of the base plate  19  and then enters the open rotary latch jaws  20  of the rotary latch  1 . The locking bar (not shown) then acts on a flank of the rotary latch jaws  20  and pivots the rotary latch  1  against the restoring force of the rotary latch spring  13  past the prelatching position shown in  FIG. 10 , in which a prelatching stage  10  of a pawl  2  lies under a latching shoulder  8  of the rotary latch  1 , until the rotary latch reaches the closed position shown in  FIG. 1 , in which the main latching stage  9  of the pawl  2  lies under the latching shoulder  8 . If the lock is in the door of a motor vehicle, then the opposing part of the lock, which can be the previously mentioned locking bar or a U-bracket, is mounted on the frame of the vehicle body. If the lock is used on a trunk lid or on a hatch cover/side door, then the lock can be on the vehicle body or on the hatch cover/door. It then also acts together with a locking bar or with a U-bracket, which, when the hatch cover/door is being closed, enters the capture slot  27  and then the rotary latch jaws  20 . 
         [0025]    The rotary latch  1  is supported so that it can rotate around a rotary latch axis  1  on the base plate  19 . The rotary latch spring  13  is designed as a torsion spring. A first leg of the spring is supported against the base plate  19 , whereas the second leg is supported against the rotary latch  1 , so that torque can be exerted on the rotary latch  1  in the direction toward the open position shown in  FIG. 6 . 
         [0026]    The pawl  2  is supported on the base plate  19  so that it can pivot around a pawl axis  2 ′; the pawl has a first arm, which forms the main latching stage  9  and the prelatching stage  10 . A second arm of the pawl  2  is actuated by a pawl spring  14 . In the exemplary embodiment, the pawl spring  14  is designed as a torsion spring, which actuates the pawl  2  in the direction toward its blocking position shown in  FIG. 1 . The two arms of the pawl  2  thus consist of a blocking arm, which provides the latching stages  9 ,  10 , and a working arm, more-or-less directly opposite the blocking arm, upon which the pawl spring  14  acts. 
         [0027]    An actuating arm  3 , which is made of plastic, is also supported rotatably around the rotational axis  2 ′ of the pawl. For this purpose, the actuating arm  3  is provided with a bearing eye  3 ″. The radially outermost end of the actuating arm  3  forms a working end  3 ′, on which a takeoff arm  6 ″ of a transmission lever  6  acts. 
         [0028]    The pawl  2  forms a driver  11 , projecting from the pawl&#39;s plane of rotation. This driver  11 , designed as a stud, lies in a niche in the actuating arm  3 , the rear wall of which forms a stop shoulder  12 , which, in the closed position shown in  FIG. 1 , is a certain free travel distance away from the driver  11 . 
         [0029]    In the closed position shown in  FIGS. 1 and 2 , the takeoff arm  6 ″ of the transmission lever  6  is a certain distance away from the working end  3 ″. The transmission lever is supported rotatably on the base plate  19  and forms a drive arm  6 ′, which projects more or less at a right angle to the takeoff arm  6 ″. The end of the drive arm  6 ′ is designed as claw-like coupling openings. The end of the drive arm  6 ′ consists of two arm sections, extending parallel to each other in a fork-like manner. The end of a coupling pin, which is permanently connected to the fixed end  4 ″ of a belt  4 , passes through the two coupling claws formed by each arm section. 
         [0030]    The belt  4  consists of plastic and forms a one-piece molded unit together with the coupling pin and a winding body  5 . The belt  4  is connected tangentially to the winding body  5  at a connecting point  4 ″. 
         [0031]    The winding body  5  preferably has an eccentric shape. It can also be round, however, with a rotational axis in the center. It is seated on a drive axis  7 , which can be turned by an electric motor  18 . The essentially circular circumferential contour of the winding body  5  is eccentric to its rotational axis  7 . 
         [0032]    A torsion spring  15 , which is designed as an actuating leg spring, one leg of which is supported against the base plate  19  while the other is supported against the actuating arm  3 , is wound around the pawl support axis  2 ′ to actuate the actuating arm  3  in the direction toward the blocking position of the pawl  2 . In the closed position shown in  FIGS. 1 and 2 , a storage hook  16  formed on the actuating arm  3  extends over a storage web  17 , which forms an arc centered on the bearing axis  1 ′ of the rotary latch  1 . On the side facing the bearing axis  1 ′, the storage web  17  has a ramp-like bevel, along which the storage hook  16  can slide when the actuating arm  3  is shifted in the direction toward the release position of the pawl  2 . The side of the storage web  17  facing away from the bearing axis  1 ′ is vertical, so that the storage hook  16  can support itself against it, which prevents the actuating arm from moving toward the blocking position. 
         [0033]    The rotary latch  1  and the pawl  2  are plastic-jacketed steel bodies. The pawl  2  has a steel core  24 , which has a stud which forms the driver  11 . It can be seen in  FIG. 14  that the pawl  2 , which is made as a stamped part, forms both a prelatching stage  10  and a main latching stage  9 . Whereas the prelatching stage  10  is covered by the pawl jacketing  25 , the steel core  24  of the pawl  2  is exposed in the area of the main latching stage  9 . Behind the main latching stage  9 , the pawl jacketing  25  forms a spring web  23 , which rests against the free end  8 ′ of the latching shoulder  8  of the rotary latch  1  to avoid rattling. The rotary latch  1  is provided with a plastic jacket except for the latching shoulder  8 . 
         [0034]    Both the rotary latch  1  and the pawl  2  have a base body of steel, which can be a stamped part. Both base bodies are overmolded with plastic jackets  25 . In the case of the pawl  2 , the driver stud  11  is also overmolded with plastic. The pawl  2  and the rotary latch  1  lie in a common plane of rotation. Also located in this plane are the two latching sites  8 ,  9  and  9 ,  10 . 
         [0035]    The lock functions in the following way: 
         [0036]    In the closed position shown in  FIGS. 1 and 2 , the rotary latch  1  is held by the main latching stage  9  of the pawl  2 . This stage lies under the latching shoulder  8  of the rotary latch  1 . The latching shoulder  8  has a positive angle, so that, when torque acts on the rotary latch  1  in the opening direction, a certain torque is exerted on the pawl  2  in the direction toward its release position. To prevent this torque from pivoting the pawl  2  into its release position, the blocking cam  21  of the transmission lever  6  lies in a niche in the pawl  2  in the closed position, this niche forming a blocking shoulder  22 . As a result, the pawl  2  is held positively in its blocking position. 
         [0037]    To open the lock, the electric motor  18  is turned on. The belt  4 , which, in the closed position, forms a relaxed arc, is wound up onto the winding body  5  until it is tensioned. The drive end  4 ′ of the belt  4  now exerts torque on the transmission lever  6 . This lever pivots until the takeoff arm  6 ″, which is a certain distance away from the working end  3  when the closed position is present, contacts the working end  3 ′. As the rotation of the transmission lever continues, the actuating arm  3  is pivoted further by the action of the takeoff arm  6 ″ on the working end  3 ′ until the position shown in  FIG. 3  is reached, wherein the free travel distance between the stop shoulder  12  and the driver  11  is used up. In the position of the lock shown in  FIG. 3 , the winding body  5  has reached the rotational position shown in  FIG. 4 , in which the “arm” of the eccentric winding body  5  acting on the belt  4  is at a minimum, which means that the electric motor is now exerting maximum tractive force on the belt  4 . As a result of this tractive force, the pawl  2  is carried along by the actuating arm  3 , wherein the position of the main latching stage  9  relative to the latching shoulder  8  shifts until the release position shown in  FIG. 5  is reached, in which the rotary latch  1  is free to rotate into its open position under the force of the tensioned rotary latch spring  13 . The length of the belt  4  and the eccentric arrangement of the rotational axis  7  relative to the eccentric circumferential surface of the winding body  5  are selected so that the belt exerts its greatest tractive force at the point when the latching engagement between the latching shoulder  8  and the main latching stage  9  is overcome. 
         [0038]    As a result of the pivoting movement of the actuating arm  3 , the storage hook  16  has slid over the storage web  17 . Now, even if, in the release position of the pawl  2  shown in  FIG. 5 , the electric motor  18  relaxes the belt  4 , the actuating arm  3  and thus also the pawl  2  cannot pivot backward. Proceeding from the position shown in  FIG. 5 , the rotary latch  1  can now pivot into the open position shown in  FIG. 6 .  FIG. 7  shows the rotational position of the winding body  5  in the fully pivoted position of the actuating arm  3  and the pawl  2 . 
         [0039]    Once the open position shown in  FIGS. 6 and 7  is reached, the motor  18  is operated in the opposite direction, so that the belt  4  relaxes. As a result of this belt relaxation, the actuating arm  3  and the pawl  2  pivot backward until the ramp-like flank  28  of the pawl  2  strikes the radially outermost  8 ′ of the latching shoulder  8 . This section forms a slide section  8 ′, which, upon rotation of the rotary latch  1  in the direction toward its closed position, slides along the ramp-like flank  28 . Thus the pawl  2 , proceeding from the open position of the rotary latch  1  shown in  FIG. 9 , pivots slightly in the direction toward its release position, until the slide section  8 ′ has passed beyond the ramp-like flank  28  and occupies the prelatching position shown in  FIGS. 10 and 11 , in which the pawl spring  14  has pushed the pawl  2  back again in the direction of its blocking position, wherein the prelatching stage  10  lies under the latching shoulder  8 . 
         [0040]    When, proceeding from the prelatching position shown in  FIGS. 10 and 11 , the rotary latch moves even farther toward its closed position, the slide section  8 ′ slides along another ramp-like flank  29  of the pawl  2  until the slide section  8 ′ has passed completely beyond this ramp-like flank  29  and the main latching stage  9  swings under the latching shoulder  8 . This closed position, shown in  FIG. 12 , corresponds to the operating position according to  FIG. 1 . 
         [0041]    It can be derived from  FIG. 14  that the ramp-like flank  28 , which contains by way of a rounded corner into the prelatching stage  10 , as well as the prelatching stage  10 , is jacketed with plastic. The ramp-like flank  29 , which also continues by way of a rounded corner into the main latching stage  10 , is not jacketed. It can also be seen in  FIG. 14  that the spring web  23  is fabricated out of the same plastic material as the pawl jacketing  25 . When the pawl  2  is in the blocking position, the spring web  23  acts on the outermost section  8 ′ of the latching shoulder  8 . As a result of the force of the pawl spring  14  acting on the pawl  2 , the spring web  23  lies under slight spring pretension against the rotary latch  1 . 
         [0042]    Both the rotary latch  1  and the pawl  2  are made simply from flat pieces of steel. All of the contours on the wide sides are formed by the associated jacketing of plastic. The only exception to this is the driver  11 , which is formed by a cylindrical steel stud, which is force-fit into an opening in the pawl  2 . The latching shoulder is integral with the material of the core of the rotary latch  1 , and the two latching stages  9 ,  10  are integral with the material of the core of the pawl  2 . 
         [0043]    While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principle.