Abstract:
A closure device, especially for vehicle doors, possesses a rotary latch interacting with a closure pin, a releasable ratchet for arresting the door, and a motor-driven shutting aid, which moves the door into the closed position. A problem from safety aspects is activating the shutting aid if fingers or articles are still located between the door and the bodywork. In order to reduce the risk of injury or damage, when the release mechanism is actuated, the force flow between the drive of the shutting aid and the door to be closed is simultaneously mechanically interrupted. As a result of this measure, the rotary latch is immediately released and the door springs open.

Description:
FIELD AND BACKGROUND OF THE INVENTION 
     The invention relates to a closure device for doors or the like, especially of motor vehicles, having a rotary latch which interacts with a pin for the locking of the door, a ratchet which arrests the rotary latch at least in the closed position of the door and which can be released with the aid of a release mechanism, and a motor-driven shutting aid, whereby the door can be pulled over the last part of its closing travel into the closed position. 
     Such closure devices are known, for example, for the tailgates of vehicles in which the gate only needs to be rested lightly against the bodywork and is then pulled into the closed position by the drive of the shutting aid. Such shutting aids may become problematical if, during the closing of a door or tailgate of a vehicle, activation of the shutting aid takes place although fingers or articles are still trapped between the gate and the frame. As a result there is a considerable risk of injury or risk of damage to the vehicle, the shutting aid and the trapped article, especially since in the case of known devices actuation of the release mechanism is also ineffective while the shutting aid is in operation. Even switching off the drive of the shutting aid fails to result in the desired opening of the door because the drives are usually of self-locking design, the door or gate merely being halted in its instantaneous position. Electronic detection of a trapped finger or article by evaluation of the load current of the drive motor is impossible because the increase in load is only slight. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a closure device for doors, hoods, gates and the like which reduces the risk of injury or risk of damage when the shutting aid engages. 
     The object is achieved, according to the invention, in that, when the release mechanism is actuated, the force flow between the drive of the shutting aid and the door to be closed is simultaneously mechanically interrupted. 
     With the aid of the closure device according to the invention it is possible, for the first time, by simple actuation of the release mechanism, not only to move the ratchet aside, as a result of which the rotary latch is released, but also to achieve an interruption of the force flow to the shutting aid and so to ensure free rotatability of the rotary latch, so that, even in the case of self-locking drives of the shutting aid, the door or gate can be open slightly or springs open automatically under the pressure of the sealing rubber and the restoring force of the preloaded rotary latch. Fingers or articles cannot become jammed between door and frame in the first place, or at least rapid opening of the door is ensured if such a misfortune has arisen. As already indicated, the closure device according to the invention is particularly suitable for doors, gates or hoods of motor vehicles, and a use with other doors, gates or flaps, for example in the field of construction engineering, is conceivable. 
     Preferably, the drive of the shutting aid acts on a first eccentric member which entrains the rotary latch on the last section of its travel into the closed position. Such a drive is of simple construction and permits the gear ratio to be selected within a wide range, this being determined, inter alia, by the lever ratios existing between the first eccentric member and its pivot and between the point of engagement of the eccentric member on the rotary latch and its pivot. 
     In order to permit closing of the rotary latch even when the eccentric member comes to a halt in the region of the shutting position as a result of a defective drive motor, the first eccentric member preferably acts on an intermediate piece which is mounted on the pivot of the rotary latch, entrains this into the closed position and can be twisted in the opposite direction against the load of a preloaded spring relative to the rotary latch. With such an embodiment, any blocked eccentric member merely blocks the intermediate piece, while the movable rotary latch permits an emergency closure of the door or gate. 
     In a particularly preferred embodiment of the closure device according to the invention, the first eccentric member is arranged on a multi-membered toggle lever which is retained in a basic position by a preloaded spring, in which position the necessary shutting forces can be transmitted to the rotary latch, and which can be moved by mechanical engagement into a bent-in position in which the first eccentric member moves out of its entraining position. 
     The interruption of the force flow via the bending-in of a toggle lever offers the advantage that the latter automatically returns to its basic position, as a result of the preloaded spring, after completion of the release action and the system is thus restored to its original state. Breaker couplings in the force flow are also conceivable, but involve the problem that, after release has taken place, there may in some cases no longer be a defined position of the eccentric member or of any other drive member relative to the shutting of the door and to the drive motor. Toggle levers also offer the possibility of influencing the actuating force necessary to bend in the toggle lever easily by varying the lever lengths and position of the joints, and varying the point of contact, the mechanical engagement preferably taking place at a point on the toggle lever at which only a slight force is necessary to bend in the toggle lever and a short displacement travel is sufficient to move the toggle lever beyond a dead-center position. As soon as the dead-center position is passed, the further bending-in of the toggle lever against the pre-stress of the preloaded spring is effected by the drive motor of the shutting aid. The eccentric member, as it moves aside, releases the rotary latch so that a blockage is ruled out. 
     The release mechanism is preferably so designed that is has a manually actuated and/or motor-actuated actuating lever which, in its open position, moves the ratchet out of the engagement with the rotary latch and bends in the toggle lever, in which case it can act directly on the toggle lever. With such a construction, the release mechanism can be kept very simple, it being preferable for the actuating lever to be mounted about a common pivot with the ratchet and the latter to be capable of being twisted relative to the actuating member by the exertion of pressure by the rotary latch against a preloaded spring. This last measure ensures that the toggle lever can be bent in only when the actuating lever is actuated, so that accidental releases are avoided. 
     Preferably, a motor-driven second eccentric member entrains the actuating member for release purposes, provision being made, in a particularly advantageous embodiment of the invention, for the two eccentric members to be driven by a common motor which is movable between two end positions of a gearing, the door closing in the region of one end position of the first eccentric member and the second eccentric member releasing the ratchet via the actuating member in the region of the other end position with a reversed direction of rotation of the motor. In this embodiment it is possible, at low cost and with only one drive motor, also to provide motor-driven release of the closure device, in which case of course a manual intervention, or automatic intervention independent of the joint drive motor, should be provided in order to interrupt the force flow which interrupts the force flow even before the joint drive motor acts on the actuating lever. In addition to eccentrically arranged bolts, cam disks, for example, are also conceivable as eccentric members. The first eccentric member for driving the shutting aid is stepped down because of the greater forces, in other words it rotates more slowly than the second eccentric member which is designed to release the closure device as quickly as possible. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An example of embodiment of the invention is described in detail below with reference to the attached drawings, in which: 
     FIG. 1 shows a view of a closure device for installation in a vehicle door or tailgate; 
     FIG. 2 shows a functional diagram of the closure device according to FIG. 1 at the start of the closure operation; 
     FIG. 3 shows the closure device according to FIG. 2 with the shutting aid activated; 
     FIG. 4 shows the closure device according to FIG. 2 shortly before the closed position is reached; 
     FIG. 5 shows the closure device according to FIG. 2 with the rotary latch locked in the standby position; 
     FIG. 6 shows the closure device according to FIG. 2 in an emergency release position; 
     FIG. 7 shows the closure device according to FIG. 2 in the released position; and 
     FIG. 8 shows the closure device according to FIG. 2 in the open position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows a closure device  10  for a vehicle tailgate. The closure device is mounted at a suitable point on the tailgate (not shown) and interacts with a closure pin  12  (see FIGS. 2 to  8 ), fixedly mounted on the bodywork, when the gate is closed. 
     The closure device  10  essentially comprises a transmission casing  14  on which an electric motor  16  is fixed by a flange, this motor driving, via a transmission arranged in the transmission casing  14 , a shutting aid  18  and a release aid  20 , and a lock, covered in FIG. 2 by a lock casing  22 , which essentially consists of a ratchet  24  and a rotary latch  26  which are pivotably arranged on the transmission casing  14 . The lock casing  22  possesses a guide aperture  28  which, during the closure of the tailgate, ensures exact positioning of the rotary latch  26  relative to the closing pin  12 . 
     The electric motor  16  is reciprocally movable between two end positions which are defined by a toothed wheel segment (not shown) seated on the pivot of the shutting aid  18 , at least one stop arranged on the casing side projecting into the segment section thereof and thus confining the pivoting path of the shutting aid  18  to approximately 90° between the shutting position shown in FIG.  4  and the release position shown in FIG.  7 . 
     The shutting aid  18  essentially consists of a toggle lever  32  which can be driven to rotate about a pivot  30  and has a first eccentric member  34  arranged at the end thereof, further details of the construction of the toggle lever  32  and its function being given in due course. 
     When the shutting aid operates, the eccentric member  34  interacts with an active lever  36  of an intermediate piece  38  which is pivotably mounted together with the rotary latch  26  about a rotary latch pivot  40 . The intermediate piece  38  is prestressed with the aid of a pivot-angle spring  42  against a stop on the rotary latch  26 , so that the rotary latch  26  can be entrained in the closure direction by the intermediate piece  38 . In the direction of opposite relative rotation, the rotary latch  26  can be twisted relative to the intermediate piece  38  to ensure that, if the intermediate piece  38  is blocked, for example as a consequence of a defective shutting aid  18 , closure of the tailgate is nevertheless possible. 
     The ratchet  24 , which is mounted to pivot about a ratchet pivot  44 , possesses a latching nose  46  (see FIGS. 2 to  5 ) which, in the corresponding rotational position of the rotary latch  26 , interacts with a preliminary catch  48  (see FIG. 3) provided on the rotary latch to arrest the tailgate in a preliminary latching position, or with a main catch  50 , likewise arranged on the rotary latch  26 , to retain the tailgate in its closed position (see FIG.  5 ). It is also conceivable for the rotary latch  26  to be designed with only one catch and the ratchet  24  with two catches to bring about the two latching positions. 
     An actuating lever  52 , also mounted to pivot about the pivot  44 , is provided to move the ratchet  24  aside into a position releasing the rotary latch  26  and, via a retaining nose  54  which comes to a stop against the end of a curved longitudinal groove  56  in the ratchet  24 , entrains the ratchet  24  during pivoting. In the unloaded state, the retaining nose  54  likewise rests against the end of the longitudinal groove  56  under the load of a preloaded spring (not shown), so that a relative pivoting of the ratchet  24  relative to the actuating lever  52  is possible (see, for example, FIGS.  3  and  8 ). A second eccentric member  58  is provided to pivot the actuating lever  52  into a position releasing the ratchet  24  (see FIG. 7) and is pivotable against the load of a preloaded spring (not shown) about a pivot  60 . The preloaded spring holds the eccentric member against a stop in a position of rest (see FIGS. 2 to  5 ), which simultaneously defines the end stop of the actuating lever  52  by bearing on the second eccentric member  58 . 
     A hand lever  62 , rigidly connected for rotation to the second eccentric member  58 , is provided, is mechanically connected to the tailgate handle, and permits manual release of the closure apparatus. 
     Also arranged on the pivot  60  is a rotatable entraining member  64  which is likewise coupled via the transmission to the electric motor  16  but possesses an opposite direction of rotation to the shutting aid  18  and, because of a different step-down ratio, possesses a wider range of twisting of almost one complete rotation between the two end positions (see FIGS.  4  and  7 ). The entraining member  64  is so designed that it entrains the eccentric member  58  only in a restricted range of rotation during release of the closure device and, moreover, performs a free rotary movement. This uncoupling also ensures that the hand lever  62  can be actuated independently of the position of the entraining member  64 . 
     As a special feature, the actuating lever  52  possesses an actuating cam  66 , with the aid of which the actuating lever  52  can act on the toggle lever  32  of the shutting aid  18 . 
     The toggle lever  32  consists of a first, L-shaped lever member  68 , on which the first eccentric member  34  is arranged and which is mounted to pivot about a first rigid pivot pin  70  on a retaining plate  72  which is pivotable about the pivot  30  of the shutting aid  18 , a second lever member  74 , which is mounted to pivot about a second rigid pivot pin  76  on the retaining plate  72 , and a middle lever member  78 , which connects the other two lever members  68 ,  74  to one another in an articulated manner. A preloaded spring  80  holds the toggle lever  32  in an extended position, in which the middle lever member  78  rests against a stop  82 . In this position, the toggle lever  32  is able to exert the necessary shutting forces on the active lever  36 , via the first eccentric member  34 , to shut the rotary latch  26 . 
     Also provided on the second lever member  34  is a contact surface  84  which, on actuation of the releasing aid  20 , interacts with the actuating cam  66  arranged on the actuating lever  52  in a corresponding position of the shutting aid  18  (see FIG.  6 ). In this case, the toggle lever  32  is bent in against the force of the preloaded spring  80 , as a result of which the first eccentric cam  34  moves out of the area of engagement with the active lever  36 . The geometry of the toggle lever  32  is so designed here that a short actuating path covered by the actuating cam  86  is sufficient to move the toggle lever  32  beyond a dead-center position, whereupon the first eccentric member  34 , which is under load, effects the further bending-in. As a result of this, even when the toggle lever  32  is under load, only very slight actuating forces are necessary to break the force flow between the first eccentric member  34  and the active lever  36 . The rotary catch  26  is freely movable because of the simultaneously released ratchet  24 , so that the tailgate can be easily opened or springs up automatically. 
     Furthermore, the closure device  10  has a pivotably mounted additional lever  86  which holds the ratchet  26  in an open position after release via a catch  88  until it is moved out of the locking position by the opening rotary latch  26  and the intermediate piece  38  pivoting with it, and releases the ratchet  24 . The additional lever  86  prevents the ratchet  24  from snapping back into the latching position again directly after release, for example if the tailgate is covered in snow and cannot spring open as a result. 
     FIGS. 2 to  8  show various positions of the closure device  10 , FIGS. 2 to  5  showing the closure operation, FIG. 6 the emergency release position and FIGS. 7 and 8 the automatic release operation. In FIG. 8, the open position of the closure device  10  is shown, in which the tailgate of the vehicle is open. The shutting aid  18  is located in a central position between the two end positions of the transmission, this position being reachable with the aid of a microswitch (not shown). The rotary latch  26  is shown in its open position, prestressed by a spring (not shown), and the ratchet  24  likewise rests against the flank of the rotary latch  26  under the load of its preloaded spring. If the tailgate is now rested with slight pressure against the bodywork, the closure pin  12  enters into engagement with the rotary latch  26  via the guide aperture  28  (see FIG. 2) and presses the rotary latch  26  into its preliminary latching position (see FIG.  3 ), in which the latching nose  46  of the ratchet  24  interacts with the preliminary catch  48  on the rotary latch  26 . In this position a microswitch (not shown) is simultaneously actuated and activates the shutting aid  18 . The start of this rotational movement is already apparent in FIG. 3, the first eccentric member having just entered into engagement with the active lever  36 . Via the intermediate piece  38 , the eccentric member  34  now entrains the rotary latch  26  into the closed position shown in FIG. 4, until the latching nose  46  of the ratchet  24  snaps into the main catch  50  and thus locks the rotary latch  26 . During this, the motor runs up against the end stop defined in the transmission by the toothed wheel segment, this situation being recorded electronically and the electric motor  16  being reversed until it has again moved the shutting aid  18  into its central position (see FIG.  5 ). The closed position of rest of the closure device  10  is achieved. 
     Should the user have trapped a finger while pushing the tailgate shut or should an article still be present between the tailgate and the bodywork, the closure device  10  offers the possibility of an emergency release. This emergency release, which is brought about by manual actuation of the hand lever  62 , in other words of the tailgate handle, is shown in FIG.  6 . The second eccentric member  58  now moves the actuating lever  52 , which both releases the ratchet  24  and, via the actuating cam  66 , bends in the toggle lever  32 , so that the first eccentric member  34  is moved out of the pivot path of the active lever  36 . As a result, the rotary latch  26  is completely released and the tailgate springs open under the pressure of the sealing rubber and the preloaded spring of the rotary catch  26 . It is also conceivable, in addition to the purely manual emergency release, also to provide an additional motor-driven adjusting member, whereby the emergency release can be triggered, for example, by actuating a push-button. After an emergency release, the preloaded spring  80  of the toggle lever  32  ensures that the latter returns again into its extended position so that the closure device is immediately ready for a further closure operation. 
     For the motor-driven release of the rotary latch  26  in normal operating states, the electric motor  16  is moved toward its opposite end stop, relative to FIG. 4, as a result of which the entraining lever  64  comes into engagement with the eccentric member  58 , and moves the actuating lever  52 , and thus the ratchet  24 , into its release position (see FIG.  7 ). It is not necessary for the actuating cam  66  to act on the unloaded toggle lever  32 , which merely arises in the example of embodiment shown according to FIG. 7 as a result of the type of geometry selected. 
     The additional lever  86  locks the ratchet  24  in its open position, the additional lever  86  being unlocked when the tailgate springs open by the intermediate piece  38  springing open together with the rotary latch  26 . The closure device  10  thus returns again into its open position shown in FIG. 8, in which it is prepared for a further closing operation.