Abstract:
The invention relates to an adjustment device for producing a rotational movement that comprises an output element ( 3 ) that can be adjusted at an angle by actuating a drive element ( 2 ). The adjustment device further comprises a load moment lock ( 1 ) interposed between the drive and the output element ( 2, 3 ) that frictionally blocks a rotational movement initiated at the output element side and that transmits a rotational movement initiated at the drive element side to the output element ( 3 ). Said load moment lock ( 1 ) further comprises locking elements ( 4, 4 ′) that are disposed in a cylindrical adjustment housing ( 10 ). Upon the effect of a play-compensating device ( 5 ) that is at least partially interposed between opposite adjusting surfaces ( 41, 41 ′) of the locking elements ( 4, 4 ′) and that compensates the rotational angle play between the drive element ( 2 ), the output element ( 3 ) and the load moment lock ( 1 ), the clamping surfaces ( 43, 43′, 43″, 43 ′″) are forced apart with such a force that they rest against the adjustment housing ( 10 ) with a predetermined pre-load. The adjustment device is provided with a play-compensating device ( 5 ) that for both directions of rotation radially.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority of International application number PCT/DE00/03935, filed Nov. 3, 2000, which in turn claims priority of German application number 199 54 232.5, filed Nov. 4, 1999. 
    
    
     BACKGROUND 
     The invention relates to an adjustment device for a clutch with a load moment lock. 
     An adjustment device with a load moment lock is known from DE 41 20 617 C2 through which torque on the drive side is transferred in both directions to an output element whilst torque on the output side is blocked in both directions by the load moment lock and the force is directed into an adjustment housing and is therefore not transferred to the drive element. 
     Torque on the drive side is transferred between the drive element and the load moment lock by means of elements which engage in each other with keyed connection. Since the position of the locking elements of the load moment lock changes through tolerance and wear as a result of high surface pressure, for the functional reliability of the known adjustment device it is necessary to incorporate a large amount of play so that rotational angle play is present between the interengaging elements conditional on the function without which a stepped transfer or change of direction of the torque on the drive side is not possible. A minimum rotational angle play must also therefore be present between the interengaging elements of the drive element and load moment lock in order to prevent any wear and to permit a certain elastic deformation. 
     However too much rotational angle play, particularly with a stepped transfer of the torque on the drive side, becomes unacceptably noticeable since the rotational angle play causes a correspondingly large idling path or idling stroke of the drive element. Moreover when reversing movement too much rotational angle play can lead to troublesome reverse play and to inaccurate handling. 
     The known adjustment device has a relatively larger reverse play in the brake unit conditioned by tolerances in the component parts. In order to restrict this it is necessary to carry out production accurately within a narrow tolerance band. The assembly of the individual component parts which are provided with low tolerances is expensive since the component parts which are to be connected together have to be positioned precisely relative to each other. 
     In order to minimize the rotational angle play between a drive element, an output element and a load moment lock and to ensure a secure force or torque transfer without any additional adjustment of the rotational angle play during assembly or re-adjustment of the rotational angle play after longer use, an adjustment device is proposed in the prior patent application 199 26 994.7 wherein between the drive element and the load moment lock or between the output element and the load moment lock there is a play compensating device which compensates the rotational angle play between the drive element, the output element and the load moment lock and with which the functionally conditioned rotational angle play between the drive element and the load moment lock or the load moment lock and the output element is automatically set and adjusted respectively. 
     To this end the load moment lock has in a cylindrical adjustment housing two locking elements arranged in pairs in two planes one above the other wherein the clamping faces through the action of the play compensating device bear against the adjustment housing with a predetermined pretension in that the play compensating device is arranged at least in part between the opposing expanding faces of the pairs of locking elements and forces the pairs of locking elements apart. The torque introduced on the output side increases the contact pressure of the clamping faces and thus of the pairs of locking elements against the adjustment housing. 
     The play compensating device furthermore serves to ensure the locking elements bear against the adjustment housing with the predetermined pretensioning force and to ensure an automatic re-adjustment which becomes necessary through wear on the component parts. It can consist for example of a wedge mounted between the expanding faces of the pairs of locking elements, whereby the wedge faces lie opposite the expanding faces of the pairs of locking elements and the wedge is guided displaceable with a wedge guide with keyed engagement in a slide guide of the drive element and is pretensioned radially by means of a spring so that the wedge faces rest against the expanding faces free of play. Alternatively the play compensating device can be formed as a cylindrical roller or ball or as an eccentric which is mounted rotatable between the expanding faces of the locking elements and is preferably designed as a stepped bolt. 
     An automatic adjustment of a minimum rotational angle play thereby takes place in both directions of rotation of the adjustment device taking into consideration the tolerances in the component parts and an automatic readjustment takes place to account for any wear on the component parts so that a minimum idling stroke is guaranteed during operation in both directions of rotation and high functional reliability is ensured for the adjustment device taking into account unavoidable wear. The manufacture of the individual component parts is thus considerably more cost-effective, assembling the adjustment device becomes easier and waste is restricted to a minimum. 
     SUMMARY 
     The object of the present invention is to provide an adjustment device with optimum rotational angle play between a drive element, an output element and a load moment lock which during assembly requires no adjustment and even after longer use requires no re-adjustment of the rotational angle play and which can be constructed simply and in space-saving manner. 
     The solution according to the invention provides an adjustment device which ensures optimum rotational angle play between a drive element, an output element and a load moment lock and which requires neither adjustment during assembly nor re-adjustment of the rotational angle play even after longer use. Since the locking elements are only arranged in one plane of the load moment lock the adjustment device can be constructed very easily and in space-saving manner, although there is a change-over play when changing over from one adjustment direction into the other. 
     Preferably the play compensating device has wedge faces which bear against the output element and/or against the locking elements, and at least one spring which pretensions the play compensating device perpendicularly to the axis of the load moment lock in the sense of reducing the distance between the play compensating device, the output element and the locking elements. 
     Through the wedge faces in connection with the pretensioning force of the spring the locking element faces are constantly brought to bear against the cylindrical adjustment housing and thus optimum rotational angle play is guaranteed during setting up and even after longer term use of the adjustment device. 
     In order to avoid any resetting of the locking element surfaces which would break down the contact between the locking element surfaces and the cylindrical adjustment housing after operation of the adjustment device, the wedge faces include such an angle with the axis of symmetry of the load moment lock that the connection is self-locking between the play compensating device on the one hand and the output element and/or the locking elements on the other hand. 
     The wedge faces can be provided selectively between the play compensating device and the output element and/or between the play compensating device and the locking elements. In a first embodiment of the invention the wedge faces of the play compensating device bear against counter wedge faces of the output element and substantially flat faces of the play compensating device bear against the facing expanding faces of the locking elements or parts of the expanding faces. 
     The output element can have protrusions or curvatures formed symmetrical with the axis of symmetry of the load moment lock for spot or linear contact with substantially rectilinear or inclined surfaces of the play compensating device. 
     Correspondingly in a second embodiment of the invention the wedge faces of the play compensating device bear against the protrusions or curvatures of the output element and substantially flat surfaces of the play compensating device bear against the facing expanding faces of the locking elements or parts of the expanding faces. 
     In a third embodiment of the invention the wedge faces of the play compensating device bear against inclined expanding faces of the locking elements and the substantially rectilinear faces of the play compensating device bear against the protrusions or curvatures of the output element. 
     A further development of the solution according to the invention is characterised in that the drive element has claws which in the event of torque on the drive side after removal of the frictional contact between the locking elements and the adjustment housing engage with keyed connection in recesses of the output element and entrain the latter in the drive direction. 
     As an alternative to this the drive element can have recesses which in the event of torque on the drive side after removal of the frictional contact between the locking elements and the adjustment housing bear with keyed engagement against claws of the output element and entrain same in the drive direction. 
     With both variations after the frictional contact between the locking elements and adjustment housing has been lifted through the action of torque on the drive side a positive locking connection is produced between the drive element and the output element and thus a slip-free connection is established between the drive element and output element. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The idea on which the invention is based will now be explained in further detail with reference to the embodiments illustrated in the drawings in which: 
     FIG. 1 shows a cross-sectional view through a load moment lock having a pair of locking elements and a device for compensating the play between the drive element, the output element and the load moment lock with adjoining wedge faces of the play compensating device and output element; 
     FIG. 2 shows a cross-section through a load moment lock as in FIG. 1 with a play compensating device with wedge faces of the play compensating device bearing against protrusions or curvatures of the output element; and 
     FIG. 3 shows a cross-section through a load moment lock as in FIGS. 1 and 2 with a play compensating device with wedge faces of the play compensating device and the locking elements contacting one another. 
    
    
     DETAILED DESCRIPTION 
     The diagrammatic illustrations of the load moment locks in FIGS. 1 to  3  show different embodiments of adjustment devices with a pair of locking elements mounted in a plane of the load moment lock and a device for compensating play between the drive element, the output element and the load moment lock. The reference numerals used coincide in all three figures where they relate to the same component parts or component parts having the same function, and only differ through the addition of a letter (a, b or c) for the different embodiments of the invention. 
     FIG. 1 shows a section through an adjustment device which operates on both sides and has an adjustment housing  10  (shown in shaded lines) in which the functional parts of a load moment lock  1   a  having automatic play compensation are mounted. In the adjustment housing there is a driver wheel  2   a  connected to a drive, for example a drive lever, as a drive element, as well as a claw like output element  3   a  whose claws  31   a,    32   a  engage through window-like recesses  21   a,    21   a ′ in the driver wheel and have a distance s from the edge of the window-like recesses  21   a,    21   a′.    
     Two circular segment like locking elements  4   a,    4   a ′ illustrated by crossed hatching rest with their clamping faces  42   a,    42   a ′,  42   a ″,  42   a ′″ which protrude from the peripheral outer face of the locking elements  4   a,    4   a ′ against the cylindrical inside face of the adjustment housing  10  and each have two semi-circular recesses  43   a ,  43   a ′,  43   a ″,  43   a ′″ in which engage the drive cams  22   a ,  22   a ′,  22   a ″,  22   a ′″ of the driver wheel  2   a  (illustrated by a thicker line) at a distance s from the wall of the semi circular like recesses  43   a,    43   a ′,  43   a ″,  43   a′″.    
     Facing the axis of the load moment lock  1   a,  the locking elements  4   a,    4   a ′ have opposing expanding faces  41   a,    41   a ′ each with protrusions or curvatures  411   a,    411   a ′;  412   a ;  412   a ′ formed symmetrical to the axis of symmetry of the load moment lock. 
     Between the locking elements  4   a,    4   a ′ and the output element  3   a  is a play compensating device  5   a  which lies by means of a spring  7   a  under pretension between the two locking elements  4   a,    4   a ′ and has the effect that the semi circular like recesses  43   a,    43   a,    43   a ″,  43   a ′″ of the locking elements  4   a ,  4   a ′ rest free of play (FIG. 2) against the drive cams  22   a ,  22   a ′,  22   a ″,  22   a ′″ of the driver wheel  2   a . The play compensation between the drive element, the output element and the load moment lock is thus established with only one locking element pair in one plane. To see more clearly the play s which exists without the action of the play compensating device  5   a,  FIG. 1 shows the drive cams  22   a ,  22   a ′,  22   a ″,  22   a ′″ of the driver wheel  2   a  spaced by the play s from the semi circular recesses  43   a,    43   a ′,  43   a ″,  43   a ′″ of the locking elements  4   a,    4   a ′. Through the action of the play compensating device  5   a  this play is eliminated and the drive cams  22   a,    22   a ′,  22   a ″,  22   a ′″ of the driver wheel  2   a  lie as shown in FIG. 2 without play against the semi circular recesses  43   a,    43   a ′,  43   a ″,  43   a ′″ of the locking elements  4   a,    4   a′.    
     For this purpose the play compensating device  5   a  has several wedge faces  51   a,    51   a ′;  52   a,    52   a ′;  53   a,    53   a ′ which rest against the corresponding counter wedge faces  33   a,    33   a ′;  34   a,    34   a ′;  35   a,    35   a ′ of the output element  3   a . On the side facing the locking elements  4   a,    4   a ′ the play compensating device  5   a  consists of flat or straight surfaces  54   a,    54   a ′ which at contact points A, A′, B, B′ contact the protrusions or curvatures  411   a,    411   a ′;  412   a ;  412   a ′ of the expanding surfaces  41   a,    41   a ′ of the locking elements  4   a,    4   a′.    
     The spring  7   a  serving to pretension the play compensating device  5   a  is thereby mounted between the angled ends  55   a ,  55   a ′ of the play compensating device  5   a  and an end face of the output element  3   a  so that the wedge faces  51   a,    51   a ′;  52   a,    52   a ′;  53   a,    53   a ′ are moved parallel outwards i.e. to the locking elements  4   a,    4   a ′ so that the locking elements  4   a ,  4   a ′ are forced parallel outwards through the contact bearing points A, A′, and B, B′. 
     The angle α between the wedge faces  51   a,    51   a ′;  52   a,    52   a ′;  53   a,    53   a ′ of the play compensating device  5   a  and the counter wedge faces  33   a,    33   a ′;  34   a,    34   a ′;  35   a,    35   a ′ of the output element  3   a  is selected so that the play compensating device  5   a  does not yield under stress, i.e. is displaced against the action of the spring  7   a.    
     The wedge faces  51   a,    51   a ′;  52   a,    52   a ′;  53   a,    53   a ′ and counter wedge faces  33   a,    33   a ′;  34   a,    34   a ′;  35   a,    35   a ′ which bear against each other under the action of the play compensating device  5  can be arranged selectively on the play compensating device  5   a,  on the output element  3   a  and/or on the locking elements  4   a,    4   a ′. In all cases the locking elements  4   a,    4   a ′ move parallel outwards during resetting of the play compensating device  5   a  so that the play between the drive element  2   a,  the output element  3   a  and the load moment lock  1   a  is eliminated or an elastic contact bearing of the drive cams  22   a,    22   a ′,  22   a ″,  22   a ′″ against the recesses  43   a,    43   a ′,  43   a ″,  43   a ′″ of the locking elements  4   a,    4   a ′ is generated for transferring a drive moment. 
     The type of play compensation between the drive element  2   a , the output element  3   a  and the load moment lock  1   a  stems from large wedge paths for small paths of the locking elements  4   a,    4   a ′ wherein the wedge angle α is measured so that the play compensating device  5   a  does not yield under stress and can be displaced against the action of the spring  7   a.    
     When the adjustment device is operated, torque introduced on the drive side through the driver wheel  2   a  as a result of the circular directed force engagement which is further away from the rotational center leads to a slight rotation of the locking elements  4   a,    4   a ′ as a result of the torque transfer from the drive cams  22   a,    22   a ′,  22   a ″,  22   a ′″ of the driver wheel  2   a  to the recesses  43   a,    43   a ′,  43   a ″,  43   a ′″ of the locking elements  4   a,    4   a ′ and then after overcoming the distance s between the claws  31   a,    32   a  of the output element  3   a  and the window-like recesses  21   a,    21   a ′ of the driver wheel  2   a  to a positive locking connection between the claws  31   a,    32   a  of the output element  3   a  and the window like recesses  21   a,    21   a ′ of the driver wheel  2   a  and thus to rotation of the output element  3   a . 
     Torque introduced on the output side through the output element  3   a  on the other hand, as a result of the more central and radially directed force engagement of the output element  3   a,  leads to forcing apart the locking elements  4   a ,  4   a ′ as a result of the force engagement of the output element  3   a  through the play compensation device  5   a  and the contact bearing points A, A′ and B, B′ respectively against the protrusions or curvatures  411   a,    411   a ′;  412   a ;  412   a ′ of the expanding faces  41   a,    41   a ′ of the locking elements  4   a ,  4   a ′ which leads to an intensification of the bearing force of the clamping faces  42   a,    42   a ′,  42   a ″,  42   a ′″ of the locking elements  4   a,    4   a ′ against the adjustment housing  10  and thus to a blocking of the torque introduced on the output side. 
     FIG. 2 shows an adjustment device with a load moment lock  1   b  and an adjustment housing  10  in which similar to the embodiment described above there is a driver wheel  2   b  connected to a drive as well as an output element  3   b  whose claws  31   b,    32   b  engage through window like recesses  21   b,    21   b ′ in the driver wheel  2   b . Two circular segment shaped locking elements  4   b,    4   b ′ bear with their clamping faces  42   b,    42   b ′,  42   b ″,  42   b ′″ against the adjustment housing  10 . Drive cams  22   b,    22   b ′,  22   b ″,  22   b ′″ of the driver wheel  2   b  engage through semicircular recesses  43   b,    43   b ′,  43   b ″,  43   b ′″ of the locking elements  4   b,    4   b ′ and rest free of play against the edges of the semicircular recesses. 
     Between the locking elements  4   b,    4   b ′ and the output element  3   b  is a play compensating device  5   b  which is forced by means of a spring  7   b  parallel between the two locking elements  4   b ,  4   b ′ and causes the recesses  43   b,    43   b ′,  43   b ″,  43   b ′″ of the locking elements  4   b,    4   b ′, to bear play free against the drive cams  22   b,    22   b ′,  22   b ″,  22   b ′″ of the driver wheel  2   b . For this purpose the play compensating device  5   b  has two inclined bearing faces or wedge faces  51   b,    51   b ′;  52   b,    52   b ′ with which it rests against cylindrical curvatures  36   b ,  36   b ′;  37   b,    37   b ′ of the output element  3   b.    
     The spring  7   b  is mounted between the angled ends  55   b,    55   b ′ of the play compensating device  5   b  and an output claw  32   b  of the two output claws  31   b,    32   b  of the output element  3   b  and is designed as a compression spring so that the play compensating device  5   b  is forced between the cylindrical curvatures  36   b,    36   b ′;  37   b,    37   b ′ of the output element  3   b  and the expanding faces  41   b,    41   b ′ of the locking elements  4   b ,  4   b ′ and thus an elastic contact bearing of the play compensating device  5   b  is generated against the output element  3   b  on one side and the locking elements  4   b,    4   b ′ on the other. The locking elements  4   b,    4   b ′ are moved parallel outwards by the play compensating device  5   b  so that the clamping faces  42   b,    42   b ′;  42   b ″,  42   b ′″of the locking elements  4   b,    4   b ′ are forced radially against the adjustment housing  10 . 
     The angle between the inclined contact bearing faces or wedge faces  51   b,    51   b ′,  52   b,    52   b ′ of the play compensating device  5   b  is selected relative to the axis of symmetry of the output element  3   b  so that the play compensating device  5   b  does not yield under stress i.e. is displaced against the action of the spring  7   b.    
     The play compensation between the drive element  2   b  formed as the driver wheel, the output element  3   b  and/or the load moment lock  1   b  takes place similar to the embodiment according to FIG. 1 over large paths of the play compensating device  5   b  with small paths of the locking elements  4   b,    4   b′.    
     Similar to the functioning of the adjustment device of FIG. 1 described above torque introduced on the drive side through the driver wheel  2   b  on account of the force engagement further away from the centre point and directed circular leads to a slight rotation of the locking elements  4   b,    4   b ′ owing to the torque transfer from the drive cams  22   b,    22   b ′,  22   b ″,  22   b ′″ of the driver wheel  2   b  to the recesses  43   b,    43   b ′,  43   b ″,  43   b ′″ of the locking elements  4   b,    4   b ′ and then after overcoming the distance between the drive cams  22   b,    22   b ′,  22   b ″,  22   b ′″ and the recesses  43   b ,  43   b ′,  43   b ″,  43   b ′″ to a positive connection between the claws  31   b,    32   b,  of the output element  3   b  and the window like recesses  21   b,    21   b ′ of the driver wheel  2   b  and thus to rotation of the output element  3   b.    
     Torque introduced on the output side through the output element  3   b  leads on the other hand owing to the more central and radially directed force engagement of the output element  3   b  to the locking elements  4   b,    4   b ′ being forced apart owing to the force engagement of the cylindrical curvatures  36   b ,  36   b ′;  37   b,    37   b ′ of the output element  3   b  against the wedge faces  51   b,    51   b ′,  52   b,    52   b ′ of the play compensating device  5   b  and further through the rectilinear faces  54   b,    54   b ′,  54   b ″,  54   b ′″ of the play compensating device  5   b  against the expanding faces  41   b,    41   b ′ of the locking elements  4   b,    4   b ′ which leads to intensification of the contact bearing between the clamping faces  42   b,    42   b ′,  42   b ″,  42   b ′″ of the locking elements  5   b,    5   b ′ and the adjustment housing  10  and thus to blocking of the torque introduced on the output side. 
     The embodiment illustrated in FIG. 3 corresponds to the adjustment device according to FIG. 2 with the measure that the expanding faces  41   c,    41   c ′ of the locking elements  4   c,    4   c ′ have inclined faces  411   c,    411   c ′,  412   c,    412   c ′ against which corresponding wedge faces  51   c,    51   c ′;  52   c,    52   c ′ of the play compensating device  5   c  bear. Rectilinear faces  54   c ,  54   c ′ of the play compensating device  5   c  bear against the cylindrical curvatures  36   c ,  36   c ′,  37   c ,  37   c ′ of the output element  3   c.    
     Also in this embodiment between the one output claw  31   c  of the output element  3   c  and the angled ends  55   c ,  55   c ′ of the play compensating device  5   c  there is a spring  7   c  formed as a compression spring and producing elastic contact between the wedge faces  51   c ,  51   c ′;  52   c ,  52   c ′ of the play compensating device  5   c  and the associated inclined faces  411   c ,  411   c ′,  412   c ,  412   c ′ of the locking elements  4   c ,  4   c′.    
     All the aforesaid adjustment devices have the basic function in common, namely in the event of drive torque acting in the direction of the output moment the lock established by the locking element is lifted but remains latently active so that an immediate locking action occurs when the drive torque is cancelled. If on the other hand the drive torque acts against the output torque then the lock is lifted and the drive torque is introduced into the output. A slight lifting or circular rotation of the locking element thereby takes place and then an immediate renewed contact bearing against the adjustment housing. 
     Through the wedge faces of a play compensating device bearing against the output element and/or against the locking elements in conjunction with the pretensioning force of a spring which pretensions the play compensating device perpendicular to the axis of the load moment lock in the sense of reducing the distance between the play compensating device, the output element and the locking elements, the locking element faces are constantly brought in contact bearing against the cylindrical adjustment housing and thus optimum rotational angle play is guaranteed when setting up and even after long service use of the adjustment device.