Abstract:
A canceling device ( 10 ) effects automatic cancellation of a switched position of a blinker switch. The canceling device ( 10 ) comprises a trigger finger ( 14 ) which can be rotated about an axis and which can also be displaced. The trigger finger is loaded towards a steering shaft by a spring ( 72 ). To reduce the dimensions of the canceling device ( 10 ), the spring is a leaf spring ( 72 ), one side of which loads the trigger finger ( 14 ) towards the steering shaft and the other side of which is supported on a casing ( 12 ) of the canceling device ( 10 ).

Description:
[0001]    This application claims Paris Convention priority of DE 100 37 585.5 filed Aug. 2, 2000 the complete disclosure of which is hereby incorporated by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    The present invention concerns a canceling device for a blinker switch in motor vehicles which is disposed in the vicinity of a steering shaft and effects automatic canceling of the blinker switch from one of the two switched positions into the neutral central position, comprising a casing and a movable trigger finger which, in the switched positions, projects into the circular path of a cam connected to the steering shaft and is pretensioned towards the steering shaft, and comprising a switching piece which is disposed about an axis substantially parallel to the steering shaft and is provided with catch elements engaging in catch profiles and which cooperates with the trigger finger.  
           [0003]    A canceling device of this type has been commercially available. When the blinker switch is actuated, the switching piece releases the trigger finger which moves radially inward towards the steering shaft and projects into the circular path of the cam connected to the steering shaft. Release of the trigger finger is effected by a helical pressure spring which is supported on one side on the trigger finger and on the other side on the casing of the canceling device.  
           [0004]    The known canceling device functions well, however, there are two main disadvantages. Modern vehicles provide only little space in the region of the steering shaft which makes installation of the relatively large-volume canceling device difficult. Moreover, the known canceling device is relatively complicated to produce so that the associated cost cannot always be justified for modern motor vehicles.  
           [0005]    It is therefore the underlying purpose of the present invention to further develop a canceling device of the above-mentioned type such that it is smaller and less expensive.  
         SUMMARY OF THE INVENTION  
         [0006]    This object is achieved in a canceling device of the above-mentioned type in that it comprises a leaf spring, one side of which loads the trigger finger towards the steering shaft and the other side of which is supported on the casing.  
           [0007]    In accordance with the invention, it has been determined that a reason for the relatively large size of the conventional canceling device is the manner in which the trigger finger is pretensioned. The known canceling device uses a helical pressure spring which requires a rather large guide to prevent bending. An intermediate piece, disposed between the spring and trigger finger, is also required.  
           [0008]    The helical pressure spring, its guide and the intermediate piece require space which is no longer available. These components are no longer required in the inventive canceling device. Leaf springs typically exhibit an intrinsic stiffness such that the guide can be omitted and a leaf spring can load the trigger finger without an intermediate piece. The overall leaf spring provided in accordance with the invention is therefore much smaller than the conventional helical pressure spring. The parts required for guiding the conventional helical pressure spring and for connection to the trigger finger can be omitted in the inventive canceling device to reduce the direct production costs and the costs for assembly of the canceling device.  
           [0009]    Further advantageous developments of the invention are given in the dependent claims.  
           [0010]    In a further development of the invention, the trigger finger comprises a projection which extends substantially parallel to the axis of the steering shaft and on which the leaf spring engages. A projection of this type produces a defined contact surface between the trigger finger and the leaf spring without requiring a separate part or special means on the leaf spring itself. The leaf spring may also abut on a rear side of the trigger finger.  
           [0011]    In a further development of the invention, a projection of this type can simultaneously serve to guide the trigger finger relative to the casing, wherein the casing is provided with a groove which extends perpendicular to the axis of the steering shaft and in which the projection engages.  
           [0012]    The inventive canceling device can also be designed such that the leaf spring is substantially circularly curved in the switched position, with the center of the circle lying approximately at the point of rotation of the switching piece. When the leaf spring is shaped and disposed in this fashion, the amount of deformation of the leaf spring caused by motion of the trigger finger from the released into the locked state, is relatively small and sufficiently uniform that the rotary motion of the trigger finger effected upon actuation thereof is not obstructed by the leaf spring.  
           [0013]    In a further development of the invention, at least one end of the leaf spring is received in a recess in the casing. A curved leaf spring which is tensioned on both sides can be borne by clamping the leaf spring between two recesses in the casing. A leaf spring which is tensioned on one side only can also be easily accommodated in this manner.  
           [0014]    One further development of the inventive canceling device is particularly advantageous with which at least one end of the leaf spring is formed on the casing. It can generally be assumed that the leaf spring is produced from a different material than the casing. This is, however, not a problem since the casing can be produced with two-component techniques. This further development considerably simplifies production of the inventive canceling device, thereby further reducing costs.  
           [0015]    It is often desirable to omit metal components for manufacture of the inventive canceling device. To nevertheless provide an amount of adjustment force which could be required from the leaf spring, a further development of the invention proposes production of the leaf spring from a fiber-reinforced plastic material, wherein it is favorable to dispose the fibers in one, longitudinal direction of the leaf spring.  
           [0016]    Relative motion occurs between the leaf spring and the trigger finger during operation, primarily the rotary motion of the trigger finger when actuated. It can therefore be advisable to reinforce the region of the leaf spring which abuts the trigger finger.  
           [0017]    An embodiment of the invention is described in detail below with reference to the accompanying drawing. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0018]    [0018]FIG. 1 shows a view, partly cut away, of essential components of a canceling device in its neutral, central position;  
         [0019]    [0019]FIG. 2 shows a view of the canceling device of FIG. 1 in one of its switched positions; and  
         [0020]    [0020]FIG. 3 shows a view of the canceling device of FIG. 1 during automatic cancellation. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]    The overall canceling device for a blinker switch in a motor vehicle is designated with the reference numeral  10  in FIG. 1. It comprises a casing  12 , a trigger finger  14  and a switching piece of which only the catch elements  16  and  18 , a triangular locking element  20  and the point of rotation  22  are shown for reasons of clarity. The overall switching piece is designated with reference numeral  24  and is symbolically indicated by dash-dotted lines with which the catch elements  16  and  18 , the triangular locking element  20  and the point of rotation  22  are interconnected. A blinker lever, also indicated only with dash-dotted lines, has been designated with reference numeral  26 .  
         [0022]    The casing  12  consists of a bottom  28  which is entirely flat, from which two triangular stops  30  or  32  extend in a perpendicular direction. The overall casing  12  is symmetrically constructed with respect to a horizontal plane (FIG. 1) having two wall sections  34  and  36  disposed perpendicularly to the bottom  28 . An opening  38  is formed between the two wall sections  34  and  36  (on the left in FIG. 1) through which the blinker lever  26  extends. An opening  40  is provided between the two wall sections  34  and  36  (right side in FIG. 1) through which the trigger finger  14  can extend (further explained below).  
         [0023]    The two wall sections  34  and  36  are designed as catch profiles comprising two catch depressions  42  and  44  or  46  and  48 . A raised locking section  50  is provided between the catch depressions  42  and  44  in the upper wall section  34  and a raised locking section  52  is provided between the two catch depressions  46  and  48  in the lower wall section  36 .  
         [0024]    The catch elements  16  and  18  of the switching piece  24  are guided in a body (not shown in the drawing). They extend, in the neutral central position shown in FIG. 1, perpendicularly from the center downwards into the catch depression  48  or perpendicularly upwards into the catch depression  44 . The radially inner sections of the two catch elements  16  and  18  are hollow and contain a helical pressure spring  54  which loads the two catch elements  16  and  18  against the wall sections  34  or  36 . The ends of the catch elements  16  or  18  facing the wall sections  34  or  36  are rounded. One semicircular cam projection  56  or  58  is formed on the radially inner ends of the two catch elements  16  and  18 , respectively.  
         [0025]    The trigger finger  14  has an overall triangular base section  60  (shown in the top view of FIG. 1) on each of whose (in FIG. 1) upper and lower corner points, one carrier foot  62  and  64  is formed. Each inner wall of the carrier feet  62  and  64  is inclined such that the width of the carrier feet  62  and  64  is smaller at the tip than in the region facing the base section  60 .  
         [0026]    A stepped projection  65  or  67  is formed in the outline of the base section  60  in the region of the upper and lower corner points which cooperate with the stops  30  or  32  in a fashion which will be described below.  
         [0027]    A carrier  66  is formed at the tip of the triangular base section  60  which projects only slightly through the opening  40  in the casing  12  in the central position of the canceling device  10  (FIG. 1). Two pins are formed on the trigger finger  14  which are aligned perpendicularly to the plane of the drawing of FIG. 1. One pin  68  is disposed in the region of the tip of the triangular base section  60  and extends towards the observer, whereas the pin  70  provided in the region of the left edge of the base section  60  extends away from the observer.  
         [0028]    A small recess (without reference numeral) is provided in the regions of the wall sections  34  and  36  extending from the top to the bottom in FIG. 1 into which one end of a leaf spring  72  is inserted which extends in a curved fashion towards the opening  40  in the casing  12  and is supported on the pin  68  in a groove (not shown). Alternatively, the leaf spring can engage at any other point of the trigger finger  14 , e.g. on the carrier feet  62  and  64  (shown in broken lines in FIG. 1). The function of the restoring device  10  is explained with reference to FIGS. 1 through 3.  
         [0029]    As mentioned above, the two ends of the catch elements  16  and  18  lie in the catch depressions  44  and  48  in the wall sections  34  and  36  in the neutral central position shown in FIG. 1 thereby locking the blinker lever  26  in the horizontal position of FIG. 1. The triangular locking element  20 , which is also part of the switching piece  24 , is located in a central position approximately on the vertically central axis of the opening  40 .  
         [0030]    The pin  70  of the trigger finger  14  abuts the tip of the triangular locking element  20 . The trigger finger  14  is loaded by the leaf spring  72  in this position which abuts the pin  68  of the trigger finger  14 . Movement of the trigger finger  14  to the right (FIG. 1), i.e. out of the opening  40  in response to the loading direction by the leaf spring  72  is prevented by the triangular locking element  20 .  
         [0031]    When the user pushes the blinker lever  26  downward, the switching piece  24  also pivots about the point of rotation  22 . The catch element  16  is thereby moved against the rising locking section  50  in opposition to the spring force of the helical pressure spring  54 . When the catch element  16  has overcome the locking section  50 , it is pressed into the catch depression  42  by the force of the helical pressure spring  54 . This position of the switching piece  24  is shown in FIG. 2.  
         [0032]    The rotary motion of the switching piece  24  produces an upward motion of the triangular locking element  20  such that the pin  70  is released from the triangular locking element  20  and the trigger finger  14  moves in the direction of the arrow  74  corresponding to the loading direction of the leaf spring  72  until it abuts with its stepped projections  65  and  67  on the stops  30  and  32 . In this position (shown in FIG. 2), the carrier  66  of the trigger finger  14  clearly projects past the edge of the opening  40 .  
         [0033]    In this position, the leaf spring  70  has a circular shape, i.e. its center coincides with the point of rotation  22 . Rotation of a steering wheel (not shown in the figure) also correspondingly rotates an associated steering shaft (also not shown in the drawing). The axis of the steering shaft is perpendicular to the planes of the drawings of FIGS. 1 through 3. Its position is represented by a dash-dotted cross designated with  76 . A carrier disc  78  is connected to the steering shaft which carries a cam  80  at its radially outer edge.  
         [0034]    Due to the rotary motion, the cam  80  forces the carrier  66  of the trigger finger  14  in the direction of the arrow  82  thereby pivoting the entire trigger finger  14  about an axis which extends parallel to the axis  76  of the steering shaft and passes through the contact point between the stepped projection  67  of the trigger finger  14  and the stop  32  of the casing  12 . Due to this pivoting motion of the trigger finger  14 , the upper carrier foot  62  (FIG. 3) presses against the cam projection  56  of the catch element  16 . This causes retraction of the catch element  16  from the catch depression  42  in the direction of the arrow  84  in opposition to the loading direction of the helical pressure spring  54 .  
         [0035]    Since the other catch element  18  is pressed by the helical pressure spring  54  at an inclined angle against the wall section  36 , the switching piece  24  is pivoted in the direction of the arrow  86  back into its neutral central position (shown in FIG. 1). During this pivoting motion of the switching piece  24 , the pin  70  formed on the trigger finger  14  slides along the triangular locking element  20  thereby pressing the trigger finger  14 , against the loading direction of the leaf spring  72 , back into its initial position shown in FIG. 1 in which the pin  70  abuts the tip of the triangular locking element  20  to lock the trigger finger  14 . In this position, the carrier  66  projects only slightly beyond the edge of the opening  40 .