Abstract:
The invention relates to a shift lever arrangement for a transmission of a motor vehicle having a shift lever for setting a selected shift stage of the transmission, with the shift lever being mounted, by means of a positioning unit, so as to be movable between a non-use position of the shift lever and a use position thereof for setting the shift stages and/or vice versa, wherein an anti-trap unit is assigned to the shift lever, in such a way that, after the activation of the positioning unit for adjusting the shift lever between the non-use position and the use position thereof and/or vice versa, the positioning force generated by the positioning unit and acting on the shift lever can be at least reduced.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
       [0001]    This invention relates to a shift lever arrangement for a transmission of a motor vehicle having a shift lever for setting a selected shift stage of the transmission, with the shift lever being mounted, by way of a positioning unit, so as to be movable between a non-use position of the shift lever and a use position thereof for setting the shift stages and/or vice versa. 
         [0002]    German document DE 197 46 438 A1 discloses a shift lever arrangement for a transmission of a motor vehicle, in which, by means of a positioning unit, a shift lever which serves for setting a selected shift stage of the transmission is mounted so as to be movable between a non-use position of the shift lever and a use position thereof. Safety measures, which protect the user of the motor vehicle from an undesired injury as a result of becoming trapped during a movement of the shift lever, are not provided. 
         [0003]    It is an object of the present invention to further develop a shift lever arrangement for a transmission of a motor vehicle in such a way that the risk of injury to the user during a movement of the shift lever from a non-use position into a use position and vice versa is reduced. 
         [0004]    To achieve this object, the invention has an anti-trap unit assigned to the shift lever in such a way that, after the activation of the positioning unit for adjusting the shift lever between the non-use position and the use position thereof and/or vice versa, the positioning force generated by the positioning unit and acting on the shift lever can be at least reduced. 
         [0005]    The particular advantage of the provision of an anti-trap unit is that the risk of injury to the user can be reduced as far as possible by reducing or deactivating the positioning force which acts on the shift lever and is generated by the positioning unit. The anti-trap unit makes it possible for a further, naturally occurring, movement of the shift lever to be prevented. 
         [0006]    According to one preferred embodiment of the invention, the anti-trap unit has a coupling device which acts on the shift lever in such a way that the movement of the shift lever is stopped as a function of an actuating force acting on the shift lever. The actuating force is the force which the user exerts on the shift lever, or on a base part which carries the shift lever, during the movement of the shift lever. The magnitude of the actuating force which leads to the movement of the shift lever being stopped can be capable of being preset. This magnitude can be relatively low, with it being possible for only a touch of the shift lever or of its base part to lead to the shift lever movement being halted. The magnitude can, however, also be dependent on the level of the degree of coupling predefined by the coupling device, and lie in a range between zero and the level of the positioning force. 
         [0007]    According to one preferred embodiment of the invention, the coupling device has a driving element which is coupled to the positioning unit and provides a positioning torque which is generated by the positioning unit. On the other hand, the coupling device has a driven element which is coupled to the shift lever and which is coupled to the driving element in such a way that the intended positioning force is exerted on the shift lever in the normal case of the shift lever movement. The driving element and the driven element are coupled to one another in such a way that, by actuating a counter-force of predefined magnitude, which acts counter to the movement of the shift lever, the driven element can be brought out of engagement with the driving element. The magnitude of the counter-force is dependent on the degree of coupling between the driving element and the driven element. 
         [0008]    According to one refinement of the invention, the driven element and the driving element are connected to one another in a form-fitting manner in the normal position, with the degree of coupling being determined by the level of the form-fitting action. The out-of-engagement position between the driving element and the driven element is produced by a counter-force which acts on the shift lever and leads to a counter-torque of the driven element, which is greater than a predefined threshold torque whose level is dependent on the degree of form-fitting action between the driving and driven element. 
         [0009]    According to another refinement of the invention, the driving element and the driven element have, on a side which faces toward one another, a corrugated profile, with a degree of elevation that determines the degree of coupling or the degree of form-fitting action. The degree of coupling can advantageously be preset in this way. 
         [0010]    According to another refinement of the invention, the driving element and the driven element are arranged coaxially with respect to one another and in a common plane. The corrugated profile of the driven element and of the driving element extends in the peripheral direction along an outer and inner peripheral edge of the driving element and of the driven element. In this way, the coupling unit can be formed in a space-saving manner in or on a frame of the shift lever. 
         [0011]    According to another refinement of the invention, the driven element has an actuating element which interacts with a switch which is fixedly arranged on a frame, in such a way that the positioning unit is deactivated when an end position of the shift lever is reached. It is advantageously possible in this way for the switch to be activated as a function of the end position of the shift lever. 
         [0012]    According to another refinement of the invention, the switch is embodied as a pressure switch, wherein in connection with a control unit, the activation and deactivation of the positioning unit takes place always after a 180° rotation of the driven element. 
         [0013]    According to yet another refinement of the invention, the driven element has an axial journal which is mounted in a guide slot of a base part of the shift lever. It is advantageously possible in this way for the rotational movement of the driven element to be converted into a linear movement of the shift lever. 
         [0014]    Further advantages of the invention are apparent from the dependent claims. 
         [0015]    An exemplary embodiment of the invention is explained in more detail below with reference to the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a perspective illustration of a shift lever arrangement according to the invention, 
           [0017]      FIG. 2  shows a front view of the shift lever arrangement, 
           [0018]      FIG. 3  shows a vertical section through the shift lever arrangement along a longitudinal central plane of a shift lever handle, 
           [0019]      FIG. 4  shows a vertical section through the shift lever arrangement, transversely with respect to the vertical section of  FIG. 3 , along the shift lever, and 
           [0020]      FIG. 5  shows a view of a driven element of the shift lever arrangement. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    A shift lever arrangement  1  for a transmission of a motor vehicle is composed substantially of a shift lever  2  which is arranged, in a pivotable fashion by means of a joint  3 , in a base part  4  of the shift lever  2 . The base part  4  is guided, by means of a vertical guide  5 , so as to be movable between an upper, use position of the shift lever  2 , which is illustrated in the figures, and a lower, non-use position of the latter, in which an upper side of a handle  6  of the shift lever  2  is arranged flush with an upper side  7  of a frame  8  of the shift lever arrangement  1 . For this purpose, a positioning unit  9  is provided which is preferably embodied as an electric motor and which is operatively connected to the base part  4  of the shift lever  2 . The positioning unit  9  is connected to a control unit  10 , which is preferably embodied as an electronic control unit comprising a microcontroller. The control unit  10  can activate the positioning unit  9  as a function of the actuation of an ignition starter switch, so that when the motor vehicle is started up, the shift lever  2 , or the shift lever  2  together with the base part  4 , can be automatically extended out of the non-use position into the use position. In the use position, the shift lever  2  serves to set shift stages of an automatic transmission. The automatic transmission can, in the conventional way, have a plurality of shift stages, such as for example parking (P), reverse (R), neutral (N) and forward (D). 
         [0022]    In order to avoid a risk of injury to the user of the motor vehicle as a result of an automatic movement of the shift lever  2  from the use position into the non-use position and vice versa, an anti-trap unit  11  is provided which substantially has a coupling unit  12  comprising a driving element  13  and a driven element  14 . The driving element  13  is fixedly connected to a driving shaft  15  of the positioning unit  9 , so that a positioning torque is applied to the driving element  13  in the positioning state of the positioning unit  9 . The driven element  14  is coupled to the base part  4  of the shift lever  2  and, in the positioning state, transmits the positioning torque which is applied to the driving element  13 . 
         [0023]    The driven element  14  has an axial journal  16  which is guided in a guide slot  17  of the base part  4 . The guide slot  17  is preferably embodied as a horizontal longitudinal groove with a length that corresponds to the outer diameter of the driven element  14 , as shown in  FIG. 2 . By rotating the circular-ring-shaped driven element  14  about a horizontal rotational axis  18 , the base part  4  is moved in the vertical direction from the use position illustrated in  FIG. 2  into the non-use position, in which the journal has been rotated 180° downward. 
         [0024]    In the present exemplary embodiment, the base part  4  of the shift lever arrangement  1  is of square design and is arranged in a recess of the frame  8  so as to be movable in the vertical direction. In order to prevent the user of the motor vehicle from becoming trapped during the movement of the shift lever  2  (positioning state), the coupling device  12  is embodied in the manner of a slipping clutch. A plurality of balls  22  are mounted in the peripheral direction between an inner peripheral face  20  of the sleeve-shaped driven element  14  and an outer peripheral face  21  of the circular driving element  13 . The inner peripheral face  20  of the driven element  14  and/or the outer peripheral face  21  of the driving element  13  has a corrugated profile  23  with troughs in which the balls  22  are mounted in each case. The balls  22  are supported, on a radially inwardly and/or radially outwardly aligned side, by springs (spiral springs). By changing the spring force of the spiral springs, it is possible for the degree of coupling between the driven element  14  and the driving element  13  to be influenced. In the positioning state of the shift lever arrangement  1 , the positioning torque is transmitted directly from the driving element  13  to the driven element  14 . The driving element  13  is in engagement with the driven element  14  via the balls  22 . By linking the driven element  14  to the base part  4 , it is possible to exert the positioning force required for moving the shift lever  2  between the non-use position and the use position and vice versa. 
         [0025]    By applying an actuating force (counter-force) which acts counter to the positioning force, the driven element  14  can be brought out of engagement with the driving element  13 , so that a further movement of the shift lever  2  in the preselected direction is prevented. The actuating force can be exerted by the user himself by pressing against the shift lever  2  or the base part  4  in the positioning state as the shift lever  2  is moving out of the recess of the frame  8 , or by pulling on the shift lever  2  as the shift lever  2  is moving into the frame  8 . To stop the movement of the shift lever  2 , the actuating force (counter-force) must be so large that a threshold torque which acts counter to the positioning torque on the driven element  14  is exceeded. The magnitude of the threshold torque is dependent on the degree of coupling between the driving element  13  and the driven element  14 . When the threshold torque is exceeded by the counter-torque, the driven element  14  “slips”, so that although the driving element  13  continues to rotate, the driven element  14  is at a standstill or even moves backward. 
         [0026]    The deeper the troughs of the corrugated profile  23 , or the greater the diameter of the balls  22  or the greater the spring force generated by the springs assigned to the balls  22 , the greater the threshold torque and therefore the counter-force required for blocking the movement of the shift lever  2 . 
         [0027]    As can be seen from the figures, the driving element  13  and the driven element  14  are arranged coaxially with respect to one another and in a common vertical plane. The driving element  13  and the driven element  14  are arranged in a space-saving fashion within the frame  8 . The axial journal  16  is arranged on a side, which faces away from the positioning unit  9 , of the driven element  14 , at which side the base part  4  adjoins the driven element  14  with play. 
         [0028]    In order to detect the upper position (use position) and lower position (non-use position) of the shift lever  2 , a switch  24  is provided which extends in the vertical direction below the driving element  13  and the driven element  14 . The switch  24  is embodied as a pressure switch which has an upward-pointing metallic or non-metallic spring which interacts with an actuating element  25  of the driven element  14 . The actuating element  25  of the driven element  14  is formed by radial elevations  26  of the driven element  14 , which radial elevations  26  are arranged so as to be distributed at an angle of 180° about the rotational axis  18  of the driven element  14  and exert a compressive force or a compression-release force on the spring of the pressure switch  24 . The radius of the driven element  14  is selected such that the driven element  14  performs a rotation of 180° during the movement from the non-use position into the use position and vice versa. A switching change therefore always takes place in the end positions of the shift lever  2 . Only one pressure switch  24  is advantageously required as a result, since the switched signal and the non-switched signal of the switch  24  are used in the control unit  10  to move the shift lever  2  into an upper and lower end position respectively. A sliding face  27  and a recessed face  28  of the driven element  14 , which sliding face  27  and recessed face  28  extend in each case in a circular fashion over 180°, are connected by means of opposing radial elevations  26  and form an outer peripheral face  29  of the driven element  14 . Said sliding face  27  and recessed face  28  each have a constant radius. 
         [0029]    As can be seen from  FIG. 2 , in the upper, use position of the shift lever  2 , the axial journal  16  is arranged at a top dead center of the driven disk  14 , so that a self-locking action is generated. It is therefore advantageously possible to prevent that, when the positioning unit  9  is not acted on, the shift lever  2  is moved out of the use position, or is moved downward into the recess of the frame  8 , as a result of a force being exerted from above. 
         [0030]    As described above, the driven element  14  is connected to the driving element  13  in a form-fitting manner by the balls  22 , which are arranged so as to be distributed in the peripheral direction. According to an alternative embodiment which is not illustrated, the driven element  14  can also be coupled to the driving element  13  by other form-fitting connections such as, for example, by a spur gear transmission and the like. It is possible for the actuating force, which leads to the shift lever movement being stopped, to be so low that only a touch of the shift lever  2  or of the base part  4  stops the movement. For this purpose, a touch sensor is required which detects a touch of the shift lever  2  or of the base part  4  or of the frame  8  and sends a signal to the control unit  10  so that the control unit  10  transmits a stop signal to the positioning unit  9 , by means of which stop signal the positioning unit  9  can be deactivated.