Abstract:
A clutch actuator assembly may include a motor provided with a rotatable worm shaft, a screw thread being formed at an exterior circumference of the worm shaft; a worm wheel having a disk shape, and provided with a worm gear engaged to the screw thread and first and second guiding holes; an operation unit mounted in the first and second guiding holes in order to move toward a radial direction of the worm wheel; and an upper body provided with a fork, and engaging or releasing a clutch by upward and downward movements of the fork corresponding to a movement of the operation unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority to Korean Patent Application No. 10-2008-0024428 filed Mar. 17, 2008, the entire contents of which application is incorporated herein for all purposes by this reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a clutch actuator assembly. More particularly, the present invention relates to a clutch actuator assembly that changes operation force applied to a clutch fork in a case in which a worm wheel is rotated by a motor. 
         [0004]    2. Description of Related Art 
         [0005]    Generally, a clutch actuator assembly is operated by hydraulic pressure and controls engaging or releasing of a clutch. 
         [0006]    A conventional clutch actuator assembly includes a clutch disk, a clutch cover, a clutch fork, an operation cylinder, a master cylinder, and a clutch pedal. 
         [0007]    The clutch disk and the clutch cover are engaged by a friction force such that torque applied to the clutch cover is transmitted to the clutch disk. That is, in a case in which the clutch disk and the clutch cover are closely contacted, the torque of the clutch cover is transmitted to the clutch disk by the frictional force. On the contrary, in a case that the clutch disk is separated from the clutch cover, the clutch disk and the clutch cover rotate independently. 
         [0008]    The clutch fork closely contacts the clutch cover to the clutch disk or separates the clutch cover from the clutch disk so as to engage or release the clutch. Such the clutch fork is operated by the operation cylinder. 
         [0009]    The master cylinder generates hydraulic pressure supplied to the operation cylinder and is mounted between the clutch pedal and the operation cylinder. Therefore, when a driver pushes the clutch pedal, the master cylinder generates the hydraulic pressure and supplies the hydraulic pressure to the operation cylinder. 
         [0010]    The conventional clutch actuator assembly is used mainly for a manual transmission. However, use of the manual transmission is decreasing because of control difficulties thereof. On the contrary, use of a double clutch transmission (DCT) or an automated manual transmission (AMT) is increasing. 
         [0011]    According to a double clutch transmission or an automated manual transmission, operation of a clutch is controlled by an electrical signal of a control unit. Therefore, it is difficult to apply the conventional clutch actuator assembly operated by the hydraulic pressure thereto. 
         [0012]    The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    Various aspects of the present invention are directed to provide a clutch actuator assembly having advantages that engaging or releasing of a clutch can be controlled by using a motor with a low capacity. 
         [0014]    One aspect of the present invention is directed to provide a clutch actuator assembly that may include a motor provided with a worm shaft, wherein a screw thread is formed at an exterior circumference thereof, a worm wheel having first and second guiding holes and provided with a worm gear at outer circumference thereof to be engaged to the screw thread of the worm shaft, an operation unit mounted in the first and second guiding holes and moving in a radial direction from or to a rotation center of the worm wheel by operation of the worm wheel, and/or an upper body including a penetration hole, and engaging or releasing a clutch by pivotal movement of an end portion thereof according to a movement of the operation unit. 
         [0015]    A fork may be formed at the end portion of the upper body to operably apply a force to a clutch cover of the clutch. 
         [0016]    A supporter may be provided to rotatably support the worm wheel, wherein the worm wheel is displaced between the upper body and the supporter and the supporter provides a biasing force to a portion of the upper body with the operation unit. 
         [0017]    The operation unit may include a ball hinge mounted in the first guiding hole, and/or an elastic member mounted in the second guiding hole. The ball hinge may further comprise an upper ball and a lower ball, diameter of the upper ball slidably disposed between the upper body and the worm wheel and larger than width of the first guiding hole, and diameter of the lower ball slidably disposed between the worm wheel and the supporter and larger than width of the first guiding hole. 
         [0018]    A cam recess may be formed at the upper body and moves pivotally the upper body upwardly or downwardly when the ball hinge moves in the radial direction in the cam recess and contact the cam recess. An interior surface of the cam recess may be slanted downwards with respect to the rotation center of the worm wheel, and an upper surface of the supporter confronting the cam recess is flat. Longitudinal axes of the penetration hole, and the cam recess may be in parallel each other. 
         [0019]    A cam hole may be formed at a lower surface of the supporter and configured to move pivotally the upper body upwardly or downwardly when the elastic member moves along the radial direction of the worm wheel in the cam hole. The lower surface of the supporter may be slanted downwards with respect to the rotation center of the worm wheel, and a lower surface of the upper body confronting the cam hole is flat. 
         [0020]    Longitudinal axis of the cam hole may be in parallel to longitudinal axis of the penetration hole. 
         [0021]    The elastic member may be mounted at a lower end of a sliding rod, an upper end of the sliding rod penetrates the upper body through the penetration hole and is connected to a head for limiting the upward movement of the upper body, wherein the head is larger than width of the penetration hole. 
         [0022]    Diameter of the elastic member may be larger than width of the penetration hole. 
         [0023]    A sliding ball sliding on the lower surface of the supporter may be mounted at a lower end of the elastic member. 
         [0024]    The first and second guiding holes may be formed obliquely to the radial direction of the worm wheel and are formed in parallel with each other. The first and second guiding holes may be spaced from the rotation center of the worm wheel with the same distance. 
         [0025]    The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description of the Invention, which together serve to explain certain principles of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is an opened-up view of an exemplary clutch actuator assembly according to the present invention. 
           [0027]      FIG. 2  is a perspective view of an exemplary clutch actuator assembly where a worm wheel is removed according to the present invention. 
           [0028]      FIG. 3  is a cross-sectional view of an exemplary clutch actuator assembly where a worm wheel is removed according to the present invention. 
           [0029]      FIG. 4  is a schematic diagram for explaining an operation of an exemplary clutch actuator assembly according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
         [0031]      FIG. 1  is an opened-up view of a clutch actuator assembly according to various embodiments of the present invention,  FIG. 2  is a perspective view of a clutch actuator assembly where a worm wheel is removed according to various embodiments of the present invention, and  FIG. 3  is a cross-sectional view of a clutch actuator assembly where a worm wheel is removed according to various embodiments of the present invention. 
         [0032]    As shown in  FIG. 1  to  FIG. 3 , a clutch actuator assembly according to various embodiments of the present invention includes a motor  10 , a worm wheel  30 , an upper body  40 , a supporter  50 , and an operation unit. 
         [0033]    The motor  10  receives an electric signal from a control unit and rotates a worm shaft  20 . A screw thread is formed at an exterior circumference of the worm shaft  20 . In addition, the control unit generates the electric signal for controlling an operation of a clutch based on a driving condition of a vehicle such as a vehicle speed and an engine speed, and transmits the electric signal to the motor  10  as a control signal of the motor  10 . The motor  10  may be a DC motor or a step motor. 
         [0034]    The worm wheel  30  has a disk shape, and a worm gear is formed at an exterior circumference of the worm wheel  30  and engages with the screw thread of the worm shaft  20 . When the motor  10  rotates, the worm wheel  30  rotates about a shaft that is perpendicular to the worm shaft  20 . In addition, first and second guiding holes  160  and  100  are formed at the worm wheel  30 , and more particularly, are formed obliquely to a radial direction of the worm wheel  30 . 
         [0035]    The upper body  40  is mounted on the worm wheel  30 . A fork  60  coupled with a clutch cover is formed at one side of the upper body  40 . The fork  60  closely contacts the clutch cover to a clutch disk or separates the clutch cover from the clutch disk. 
         [0036]    In addition, a cam recess  90  is formed on a lower surface of the upper body  40  corresponding to the first guiding hole  160 , and a penetration hole  150  is formed at the upper body  40 . The penetration hole  150  corresponds to the second guiding hole  100 . The cam recess  90  and the penetration hole  150  are formed along the radial direction of the worm wheel  30 . In addition, an interior surface of the cam recess  90  is slanted, and the lower surface of the upper body  40  near the penetration hole  150  is flat. 
         [0037]    The supporter  50  is formed under the worm wheel  30  and rotatably supports the worm wheel  30 . A cam hole  120  is formed at a location corresponding to the second guiding hole  100  of the worm wheel  30  in the supporter  50 . A lower surface of the cam hole  120  is slanted downwards, and an upper surface of the supporter  50  corresponding to the cam recess  90  is flat. In addition, the cam hole  120  is formed along the radial direction of the worm wheel  30 . 
         [0038]    The operation unit includes a ball hinge  70  mounted in and guided by the cam recess  90  and the first guiding hole  160 , and an elastic member  130  mounted in and guided by the cam hole  120 , the second guiding hole  100 , and the penetration hole  150 . 
         [0039]    Balls are mounted respectively at upper and lower ends of the ball hinge  70 . The ball hinge  70  is disposed in the first guiding hole  160 . The upper ball  72  attached to an upper end of the ball hinge  70  is inserted in and guided along the cam recess  90  rotated by the worm wheel  30 , and the lower ball  74  slides on the flat surface of the supporter  50  as the worm wheel  30  rotates. 
         [0040]    In other words, a middle portion of the ball hinge  70  connects the upper and lower balls  72  and  74 , and penetrates the first guiding hole  160 . Since the first guiding hole  160  is formed obliquely to the radial direction of the worm wheel  30 , the middle portion of the ball hinge  70  moves along the first guiding hole  160  and a moving direction of the ball hinge  70  is the radial direction of the worm wheel  30  when the worm wheel  30  rotates. For instance, in  FIG. 1 , when the worm wheel  30  rotates counterclockwise, the slanted first guiding hole  160  pushes the ball hinge  70  toward the center of the worm wheel  30  so that the distance between the ball hinge  70  and the center of the worm wheel  30  becomes shorter. In contrast, when the worm wheel  30  rotates clockwise, the slanted first guiding hole  160  pushes the ball hinge  70  outwards from the center of the worm wheel  30  so that the distance between the ball hinge  70  and the center of the worm wheel  30  becomes longer. 
         [0041]    Since the interior surface of the cam recess  90  is slanted downwards, the ball hinge  70  moves upwardly or downwardly as well as to the radial direction of the worm wheel  30 . Therefore, the upper body  40  moves upwardly or downwardly by upward or downward movement of the ball hinge  70  and thus engages or releases a clutch. 
         [0042]    A sliding rod  110  is mounted at an upper end of the elastic member  130 , and a sliding ball  140  is mounted at a lower end of the elastic member  130 . The upper end of the elastic member  130  closely contacts the upper body  40  and applies elastic force thereto. The lower surface of the upper body  40  that closely contacts the elastic member  130  is flat. 
         [0043]    The sliding rod  110  penetrates the penetration hole  150  and is connected to a head  80 . Since width of the head  80  is larger than that of the penetration hole  150 , the head  80  limits the upward movement of the upper body  40 . In addition, a middle portion of the elastic member  130  penetrates the second guiding hole  100  of the worm wheel  30 , and the sliding ball  140  is located on a lower surface of the cam hole  120 . Since the width of the sliding ball  140  is larger than that of the cam hole  120 , the sliding ball  140  slides along the lower surface of the cam hole  120 . 
         [0044]    Since the second guiding hole  100  is formed obliquely to the radial direction of the worm wheel  30 , the elastic member  130  moves along the second guiding hole  100  and a moving direction of the elastic member  130  is the radial direction of the worm wheel  30  when the worm wheel  30  rotates. 
         [0045]    For instance, in  FIG. 1 , when the worm wheel  30  rotates counterclockwise, the slanted second guiding hole  100  pushes the elastic member  130  toward the center of the worm wheel  30  so that the distance between the elastic member  130  and the center of the worm wheel  30  becomes shorter. In contrast, when the worm wheel  30  rotates clockwise, the slanted second guiding hole  100  pushes the elastic member  130  outwards from the center of the worm wheel  30  so that the distance between the elastic member  130  and the center of the worm wheel  30  becomes longer. 
         [0046]    Since the lower surface of the cam hole  120  is slanted downwards, the elastic member  130  moves upwardly or downwardly in the radial direction of the worm wheel  30 . Furthermore since the lower surface of the cam recess  90  is slanted downwards, the ball hinge  70  moves the upper body  40  upwardly or downwardly in the radial direction of the worm wheel  30 . Therefore, the upper body  40  moves upwardly or downwardly by upward or downward movement of the ball hinge  70  and the elastic member  130  and thus engages or releases the clutch. 
         [0047]    According to various embodiments of the present invention, the first and second guiding holes  160  and  100  are formed in parallel with each other, and the cam recess  90  and the cam hole  120  are slanted in opposite directions from each other. However, the spirit of the present invention is not limited to this embodiment. That is, the spirit of the present invention includes any structures in which the ball hinge  70  and the elastic member  130  move in radially opposite directions of the worm wheel  30  when the worm wheel  30  rotates. 
         [0048]    Referring to  FIG. 4 , operation of the clutch actuator assembly according to various embodiments of the present invention will hereinafter be described in detail. 
         [0049]      FIG. 4  is a schematic diagram for explaining an operation of a clutch actuator assembly according to various embodiments of the present invention. 
         [0050]    As shown in  FIG. 4A , assuming that a distance from the ball hinge  70  to the fork  60  is represented as a1, a distance from the ball hinge  70  to the elastic member  130  is represented as b1, and the elastic force of the elastic member  130  is represented as Fs at an initial state, a force Fr applied to the clutch cover by the fork  60  is represented as Equation 1. 
         [0000]        Fr=Fs *( b 1 /a 1)   Equation 1 
         [0051]    In this state, if the motor  10  is operated and the worm wheel  30  is rotated, the ball hinge  70  moves along the first guiding hole  160  and the elastic member  130  moves along the second guiding hole  100 . Therefore, the ball hinge  70  moves to the left and the elastic member  130  moves to the right as shown in  FIG. 4B . 
         [0052]    In addition, since the interior surface of the cam recess  90  guiding the ball hinge  70  is slanted downwardly to the left in the drawing, the ball hinge  70  moves to the left and lifts the upper body  40 . Similarly, since the lower surface of the cam hole  90  guiding the elastic member  130  is slanted downwardly to the right in the drawing, the elastic member  130  moves to the right and pulls the upper body  40  down. In this case, the length of the elastic member  130  increases and the elastic force also increases. However, the elastic force is designed to change within a predetermined range (i.e., a range where a change of the elastic force is small). 
         [0053]    As shown in  FIG.4B , assuming that a distance from the ball hinge  70  to the fork  60  is represented as a2, a distance from the ball hinge  70  to the elastic member  130  is represented as b2, and the elastic force of the elastic member  130  is represented as Fs at an operating state, a force Fr applied to clutch cover by the fork  60  is represented as Equation 2. 
         [0000]        Fr=Fs *( b 2 /a 2)   Equation 2 
         [0054]    Since a2 is smaller than a1 and b2 is larger than b1 when comparing Equation 2 with Equation 1, b2/a2 is larger than b1/a1. Therefore, the force Fr applied to the clutch cover by the fork  60  increases, and accordingly the fork  60  separates the clutch cover from the clutch disk. 
         [0055]    In addition, if the motor  10  rotates in an opposite direction, the force Fr applied to the clutch cover by the fork  60  decreases and the fork  60  closely contacts the clutch cover to the clutch disk. 
         [0056]    Meanwhile, means for supplying elastic force in a direction opposite to the Fr direction may be mounted at the clutch cove. 
         [0057]    As described above, because operation of a clutch is controlled by a motor, a clutch actuator assembly of the present invention can be easily applied to a double clutch transmission or an automated manual transmission. 
         [0058]    In addition, because power of a motor is used in order to only move a ball hinge and an elastic member and a clutch is operated by elastic force of the elastic member, a motor with a low capacity can be used for a clutch actuator assembly of the present invention. 
         [0059]    For convenience in explanation and accurate definition in the appended claims, the terms “upper” or “lower”, and etc. are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
         [0060]    The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.