Abstract:
An actuator apparatus for a clutch that operates the clutch of a transmission according to operation of a motor, may include the motor including a stator and a rotator, wherein the rotator has a drive shaft and a rotator core receiving the drive shaft therein, a lead screw engaged to the drive shaft of the motor and movable in a length direction thereof according to the operation of the drive shaft in the motor, a rod disposed apart from the lead screw, a slider connecting the lead screw with the rod, and a guide rail disposed to contact with the slider and guiding a linear motion of the slider.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to Korean Patent Application No. 10-2011-0132266 filed in the Korean Intellectual Property Office on Dec. 9, 2011, the entire contents of which is incorporated herein for all purposes by this reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an actuator of a clutch, and more particularly to an actuator for operating a clutch in a transmission of an electric vehicle. 
     2. Description of Related Art 
     Generally, an actuator converts electrical energy, hydraulic energy or pneumatic energy to a mechanical energy. The actuator is used to operate a clutch of a transmission. 
     In a case of a manual transmission, a clutch control system of a clutch release cylinder type or concentric sleeve cylinder type is used. 
     In the clutch release cylinder type, if a driver pushes a clutch pedal, hydraulic pressure is generated in a clutch master cylinder and a tappet of a clutch release cylinder is operated by the generated hydraulic pressure. 
     At this time, the tappet pushes a clutch release fork so as to move a clutch release bearing in an axial direction. After that, the clutch release bearing moved in the axial direction operates a clutch diaphragm spring. 
     In a case of an automatic transmission, a clutch actuator is adapted to engage and release the clutch automatically. The clutch actuator of the automatic transmission receives a signal from an electric control unit (ECU) so as to operate the clutch. The clutch actuator has a master cylinder, a device for converting a motion direction and a motor. 
     The master cylinder is connected to a slave cylinder disposed around a release device of the clutch. The device for converting a motion direction includes a rod, a worm wheel and a worm gear. The rod contacts with a piston of the master cylinder. The worm wheel is fixed to an end portion of the rod. The worm gear is coupled to the worm wheel and is fixed to a rotating shaft of a motor. That is, if the motor rotates, the worm wheel is rotated by rotation of the worm gear. Thereby, the rod is moved linearly and the piston of the master cylinder is operated. Therefore, the hydraulic pressure is supplied from the master cylinder to the slave cylinder, and the slave cylinder is adapted to operate the release device so as to engage or release the clutch. 
     However, since the number of the components including conventional clutch actuators is many, a cost may be increased and a spatial utility may be deteriorated. 
     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 
     Various aspects of the present invention are directed to providing an actuator for a clutch having advantages of reducing cost and increasing fuel economy and spatial utility. 
     In an aspect of the present invention, an actuator apparatus for a clutch that operates the clutch of a transmission according to operation of a motor, may include the motor including a stator and a rotator, wherein the rotator may have a drive shaft and a rotator core receiving the drive shaft therein, a lead screw engaged to the drive shaft of the motor and movable in a length direction thereof according to the operation of the drive shaft in the motor, a rod disposed apart from the lead screw, a slider connecting the lead screw with the rod, and a guide rail disposed to contact with the slider and guiding a linear motion of the slider. 
     The drive shaft of the motor is formed with a cylindrical shape having an interior circumference and an exterior circumference. 
     A screw thread is formed at an exterior circumference of the lead screw and a screw thread is formed at a portion of the interior circumference of the drive shaft to be engaged with the lead screw and to move the lead screw linearly in the length direction by rotation of the drive shaft. 
     The lead screw and the rod are coaxially disposed. 
     The actuator apparatus may further may include an elastic member that is disposed inside the drive shaft of the motor and elastically biases the lead screw. 
     The actuator apparatus may further may include a cam that is coupled to the lead screw positioned outside the motor. 
     The guide rail is disposed in the length direction of the lead screw. 
     The slider may include a side surface to which the lead screw is rotatably coupled, the other side surface coupled to the rod, and an upper surface and a lower surface connecting the side surface and the other side surface. 
     The guide rail is disposed to slidably contact with at least one of the upper surface and the lower surface of the slider. 
     The actuator apparatus may further may include a gap forming portion that is connected with the slider and the rod respectively and connects the slider and the rod with a space formed therebetween such that the rod moves upwardly or downwardly. 
     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, which together serve to explain certain principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an actuator for a clutch according to an exemplary embodiment of the present invention. 
         FIG. 2  is a cross-sectional view of a motor according to an exemplary embodiment of the present invention. 
         FIG. 3  is a schematic diagram showing operation of an actuator for a clutch according to an exemplary embodiment of the present invention. 
     
    
    
     It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment. 
     In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. 
     DETAILED DESCRIPTION 
     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 the 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. 
     An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a schematic diagram of an actuator for a clutch according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 1 , an actuator  10  for a clutch includes a motor  20 , a case  60 , a lead screw  30 , a rod  50 , a slider  40  and a guide rail  42 . 
     The motor  20  is adapted to generate power for operating the actuator  10 . That is, the actuator  10  is operated according to operation of the motor  20 . 
     Components such as the lead screw  30 , the slider  40 , the guide rail  42  and so on can be disposed in the case  60 . The case  60  is coupled and fixed to the motor  20 . 
     The lead screw  30  moves linearly in a length direction thereof according to the operation of the motor  20 . In addition, some portion of the lead screw  30  is coupled to the drive shaft of the motor  20 . 
     The rod  50  moves in the length direction together with the lead screw  30 . The rod  50  and the lead screw  30  are disposed on the same axis. Some portion of the rod  50  is disposed in the case  60 , and the other portion of the rod  50  is disposed at an outside of the case  60 . 
     And, a boot  70  is disposed on the rod  50  for protecting the rod  50  disposed at the outside of the case  60 . A first support portion  56  and a second support portion  62  are disposed apart from each other on the rod  50  in the length direction, and support both end portions of the boot  70 . 
     The slider  40  is adapted to guide the lead screw  30  and the rod  50  such that the lead screw  30  and the rod  50  easily move in the length direction. That is, the slider  40  is disposed between the lead screw  30  and the rod  50  and connects the lead screw  30  with the rod  50 . Therefore, the lead screw  30 , the slider  40  and the rod  50  integrally move according to the length direction of the lead screw  30 . 
     The slider  40  has a side surface coupled to the lead screw  30 , the other side surface coupled to the rod  50 , and an upper surface and a lower surface connecting the side surface and the other side surface. 
     The guide rail  42  is adapted to guide the slider  40  such that the slider  40  easily moves. The guide rail  42  can be fixedly provided at the upper surface and/or the lower surface of the slider  40  in the case  60 . That is, the guide rail  42  is adapted to contact with at least one of the upper surface and the lower surface of the slider  40 . The guide rail  42  is disposed in the length direction of the lead screw, and accordingly, the slider  40  moves in a moving direction of the lead screw according to the guide rail  42 . 
     A catching portion  32  is disposed on the lead screw  30  so as to prevent the slider  40  from being separated from the lead screw  30 . The catching portion  32  is coupled to the end portion of the lead screw  30  connected to the slider  40 . 
       FIG. 2  is a cross-sectional view of a motor according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 2 , the motor  20  generates a rotating force by a stator  21  formed with a ring shape and a rotator  25  including a drive shaft  22  disposed in the stator and a rotator core  23  disposed at an exterior circumference of the drive shaft  22 . The drive shaft  22  of the motor  20  is formed with a cylindrical shape having an interior circumference and an exterior circumference. In addition, a lead screw receiving hole  24  is a hole portion of the drive shaft  22  of the motor in which some portion of the lead screw  30  inserted. 
     A screw thread is formed at some portion of an interior circumference of the drive shaft  22 . In addition, a screw thread is formed at an exterior circumference of the lead screw  30 . Therefore, if the motor  20  is driven, the lead screw  30  moves in the length direction along the screw thread of the drive shaft according to the rotation of the drive shaft  22 . In addition, since the drive shaft  22  can rotate in both directions, the lead screw  30  can reciprocate linearly in the length direction. 
     An elastic member  26  is disposed in the lead screw receiving hole  24 . The elastic member  26  is connected to an end portion of the lead screw  30 . Therefore, the elastic member  26  can reduce a driving torque of the motor  20  and efficiently move the lead screw  30  linearly by using elastic force thereof. 
     A cam  34  is disposed at the other portion of the lead screw  30  that is not inserted in the motor  20 . And, since the cam  34  increases rotational inertia of the lead screw, the cam  34  can reduce the drive torque of the motor  20 . 
       FIG. 3  is a schematic diagram showing operation of an actuator for a clutch according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 3 , the rod  50  includes a connecting portion  54  and a gap forming portion  52 . 
     The connecting portion  54  is disposed at an end portion of the rod  50 . That is, the connecting portion  54  is formed at a portion of the rod which is not covered by the boot  70  and is disposed at the outside of the case  60 . And, the connecting portion  54  can contact with a connecting lever  82  coupled to a clutch  80 . That is, if the rod  50  moves linearly, the connecting portion  54  contacts with the connecting lever  82  and then moves the connecting lever. Accordingly, the clutch  80  is operated by the lever motion of the connecting lever  82 . Also, since the rod  50  can reciprocate linearly, the clutch  80  can be engaged or released. 
     The gap forming portion  52  is disposed at a portion where the rod  50  and the slider  40  are connected. 
     The gap forming portion  52  is respectively connected with the slider  40  and the rod  50  and connects the slider  40  and the rod  50  with a space formed therebetween such that the rod  50  moves upwardly or downwardly. The rod  50  pitches in a vertical direction to the length direction because of the lever motion of the connecting lever  82  rotating about a one point. Accordingly, the gap forming portion  52  compensates a pitch of the rod  50 . 
     According to an exemplary embodiment of the present invention, since the number of the components decreases, a cost may be reduced. Also, since the lead screw is used, a spatial utility may be improved. In addition, the clutch  80  needs not an additional energy for coupling. Therefore, fuel economy may be improved. 
     For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “inner”, “outer”, “forwards” and “backwards” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
     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.