Abstract:
The present invention is directed to an actuator assembly ( 10 ) having an actuator device ( 26 ) operably associated with a housing ( 16 ), one or more rotating gear members ( 46, 48, 52 ) operably associated with the actuator device ( 26 ), a bearing member ( 76 ) operably associated with the one or more rotating gear members ( 46, 48, 52 ), and a cam ( 66 ) operably associated with the one or more rotating gear members ( 46, 48, 52 ), for translating rotary motion of the gear members ( 46, 48, 52 ) to axial motion. When the actuator  0  device ( 26 ) is actuated, the one or more rotating gear members ( 46, 48, 52 ) rotate, causing the bearing member ( 76 ) to move on the cam ( 66 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/736,490, filed Nov. 14, 2005. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to an actuator assembly for use in a vehicle. More particularly the present invention relates to an arrangement for converting rotary motion from an actuator to axial motion. 
       BACKGROUND OF THE INVENTION 
       [0003]    Actuators are used to operate a number of devices such as fluid control valves or control mechanisms used on turbochargers. The actuators may have axial motion or they may have rotary motion that is converted to axial motion. Converting rotary-to-axial motion requires an arrangement that efficiently translates the motion. Often times such arrangements require an additional element or component that increases the complexity of the device. It is desirable to develop arrangements that eliminates complex or additional components as well as provide greater packaging advantages. Thus, the overall size, weight and cost of the device is reduced. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention is directed to an actuator assembly having an actuator device operably associated with a housing, one or more rotating gear members operably associated with the actuator device, a bearing member operably associated with the one or more rotating gear members, and a cam operably associated with the one or more rotating gear members, for translating rotary motion of the gear members to axial motion. 
         [0005]    When the actuator device is actuated, the one or more rotating gear members rotate, causing the bearing member to move on the cam. 
         [0006]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0007]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0008]      FIG. 1   a  is a front plan view of an actuator assembly, according to the present invention; 
           [0009]      FIG. 1   b  is a side plan view of an actuator assembly, according to the present invention; 
           [0010]      FIG. 2  is a sectional front plan view of an actuator assembly in a closed position, according to the present invention; 
           [0011]      FIG. 3  is a second sectional front plan view of an actuator in an open position, according to the present invention; 
           [0012]      FIG. 4  is a sectional side plan view of an actuator assembly, according to the present invention; 
           [0013]      FIGS. 5A and 5B  are isometric views of an alternate embodiment of the present invention; and 
           [0014]      FIG. 6  is a front plan view of an actuator assembly with the poppet valve replaced with a pin and the valve housing removed, according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0016]      FIGS. 1   a  and  1   b  show the front and side views of an actuator assembly  10  which includes a valve assembly  12 . Referring to  FIGS. 1-4 , actuator assembly  10  has a valve housing  14  and an actuator housing  16  designed to accept a connector/cover  18  with an integrated position sensor  20 . An elastomer seal  22  is used to seal the connector/cover  18  to the actuator housing  16 . Screws  24  secure the connector/cover  18  to the housing  16 . An actuator device such as a DC motor  26  is secured by a bracket  28 , and screws  30  to the actuator housing  16 . The connector/cover  18  has an integrated leadframe  40  made of multiple electrical conductors  34 . Terminals  32 , of the motor  26 , interconnect with the electrical conductors  34  of the electrical connector/cover  18 . The connector/cover  18  has a connector  36  with terminals  38  that provide an external connection to a suitable electronic control unit (ECU)  42 . The terminals  38  may also be a portion of the leadframe  40 . 
         [0017]    The rotating shaft  44  of the motor  26  is fitted with pinion gear  46  that engages with an intermediate gear  48 . The intermediate gear  48  is located by pin  50  in actuator housing  16 . The intermediate gear  48  engages output gear  52 . The output gear  52  rotates about output gear shaft  54 , which is located in the actuator housing  16 . The shaft  54  is guided by a bearing member  56  and bushing  58  that are also located in actuator housing  16 . The clip  60  secures the shaft  54  to the actuator housing  16 . A cup plug  62  is used to cover the opening  64  in the actuator housing  16 . A cam shown here in the form of a cam slot  66  is formed in output gear  52 . 
         [0018]    A sensor rotor  68  is attached to output gear  52  by a suitable method such as a plastic overmolding. Alternate fastening methods include ultrasonic welding, adhesives, or a “snap fit.” The sensor rotor  68  is positioned relative to the associated position sensor  20  that is part of the sensing circuit  70  attached to the connector/cover  18 . The position sensor  20  can be any type of sensor capable of detecting the position of the sensor rotor  68  and output gear  52 . For example, one type of position sensor  20  is a non-contact position sensor, such as an induction sensor. Such a sensor can have an inductor overmolded onto the output gear  52 . The electrical connections to the sensing circuit  70  are made through the leadframe  40 , conductors  34 , and terminals  38 . The sensor rotor  68  couples a signal from a transmitter to a receiver on the position sensing circuit  70 . The position sensing circuit  70  provides an output signal that is relative to the rotation and position of the output gear  52 . 
         [0019]    A stem member or valve stem  72  is fitted with a valve member or poppet valve  74  at one end and a bearing member or bearing  76  held by a pin  78  at the opposite end. The valve stem  72  is guided by a bushing  80  which is retained in valve housing  14  by suitable manner such as a press fit. Valve housing  14  has an inlet  84  and outlet  86 . Inlet  84  is fitted with a valve seat  88  that will seat poppet valve  74  and block flow between the inlet  84  and outlet  86 . 
         [0020]    The actuator housing  16  and valve housing  14  are shown as a single component. The actuator housing  16  and valve housing  14  can also be separated into two components. For example, the actuator housing  16  and valve housing  14  could be separated at the flange  90  and joined by a suitable means such as threaded fasteners  92  as shown in  FIG. 4 . 
         [0021]    A spring  94  is coaxial with the output gear shaft  54 . The spring  94  has features that engage the output gear  52  and the actuator housing  16 . The spring  94  is designed to cause the output gear  52  to rotate in a counterclockwise direction. The cam slot  66 , located in the output gear  52 , is designed to receive the bearing  76  that is attached to one end of valve stem  72 . The cam slot  66  is shaped to cause the bearing  76 , valve stem  72 , and poppet valve  74  to move in the direction of the valve seat  88  when the spring  94  applies the counterclockwise torque to the output gear  52 . The torque of the spring  94  is sufficient to cause the poppet valve  74  to seat on valve seat  88  and block flow between the valve inlet  84  and outlet  86 . 
         [0022]    The actuator assembly  10  operates through the use of an engine control unit (ECU)  42  that provides a suitable electrical signal by way of terminals  38 , leadframe  40 , conductors  34 , and motor terminals  32 . 
         [0023]    The motor  26  receives a signal from the ECU  42  and develops torque that is relative to the strength of the signal. The torque generated by the motor  26  will be transmitted through the pinion gear  46 , and intermediate gear  48  to output gear  52 . This torque will oppose the resistance of the spring  94 . When the signal and the resulting torque is sufficient, it exceeds the resistance of the spring  94  and causes the output gear  52  to rotate. Progressively increasing the signal provides a higher resultant torque that increases the degree of the output gear  52  rotation. Decreasing the signal reduces the degree of output gear  52  rotation. 
         [0024]    The cam slot  66 , formed in output gear  52 , engages with bearing  76  that is attached to valve stem  72  by pin  78 . The rotation of output gear  52  and cam slot  66 , forces the bearing  76 , pin  78 , valve stem  72 , and poppet valve  74  to move in an axial direction that unseats the poppet valve  74  from valve seat  88  and allow flow between the inlet  84  and the outlet  86 . 
         [0025]    The contour of the cam slot  66  determines the rate of axial movement versus output gear  52  rotation. The contour of the cam slot  66  also, in part, determines the operating force acting on the bearing  76 , valve stem  72 , and poppet valve  74 . The contour is varied through the rotation to provide a variable poppet valve  74  opening/flow rate through the axial stroke of the poppet valve  74  to provide the desired operating characteristics. 
         [0026]    The contour of the cam slot  66  also controls the operating force, at a specific rotation/stroke. In one embodiment, the contour of the cam slot  66  is configured to provide a continuously variable rate through the rotation of the output gear  52 . Controlling the mechanical advantage through rotation provides a method of matching the required force of the valve assembly  12  to the available torque of the motor  26 . For example, in an alternate embodiment a higher force may be provided at a specific point through the rotation of output gear  52 , by adjusting the contour of the cam slot  66 . As the motor  26  rotates the pinion gear  46 , intermediate gear  48 , and output gear  52 , the bearing  76  moves through the cam slot  66  changing the position of the valve stem  72  and poppet valve  74  relative to the output gear  52 , thereby changing the amount of force transferred therebetween. 
         [0027]    Sensing circuit  70  provides an output signal that is relative to the degree of output gear  52  rotation and axial poppet valve  74  movement. This output serves as an indication of relative flow through the poppet valve  74 . 
         [0028]    In another aspect, the electronic sensing circuit  70  may also be programmed to provide a specific signal range for a given valve stem  72  and poppet valve  74  position. For example, the poppet valve  74  in a closed position may be programmed within a specific sensing voltage range. It is believed that this capability improves the accuracy of valve stem  72  and poppet valve  74  position, as well as compensate for component and assembly variation. One way of achieving this is by accessing the sensing circuit  70  using a calibration procedure. 
         [0029]    The position sensor  20  and the output signal of the position sensor  20  are part of a closed loop control system for the poppet valve  74 . The ECU  42  is programmed with a map of engine operating conditions and a desired flow for each condition. The desired flow is translated to the sensing circuit  70  output signal and ECU  42  signal. The ECU  42  provides the signal to the motor  26  and cause the poppet valve  74  to move to a desired position. The ECU  42  adjusts the signal to achieve-or-maintain the desired poppet valve  74  position. 
         [0030]    The use of the cam slot  66 , integrated into the output gear  52 , is an effective means of converting the rotary motion of the motor  26  to axial motion of the valve stem  72 . It is to be appreciated that this concept is also applicable to other devices that require axial movement. For example, the valve housing  14  portion of the actuator assembly  10  could be removed to expose the valve stem  72 . The valve stem  72  can be connected to any device that would require axial operation, such as the control device of a turbocharger as shown in  FIG. 6 . In  FIG. 6 , a portion the valve housing  14  has been removed to expose the valve stem  72 , and the poppet valve  74  has been replaced with a pin  108 . 
         [0031]    The integration of the cam slot  66  is based upon the manufacturing process of the component. For example, in one embodiment, the cam slot  66  is molded by an injection molded process, however, the cam slot may also be cast if a metal casting process is used, or compacted if a powdered metal process is used. In other embodiments, the cam slot  66  is made as a separate part and attached by suitable means such as plastic overmolding, press fit, riveting, welding, brazing, or adhesive. Also, it is not necessary that the cam slot  66  be completely formed through the output gear  52 . In an alternate embodiment, a wall that limits the movement of the bearing  76  and valve stem  72  is utilized to provide the cam guidance. 
         [0032]    Variations of the invention may be used for translating the motion. Referring to  FIGS. 5   a  and  5   b,  the bearing  76  is attached to the output gear  52  and is offset from the center of rotation of the output gear  52 . A guide slot  98  is formed with or attached to the valve stem  72 ; the guide slot  98  is operably configured for receiving the bearing  76 . The valve stem  72  will move in an axial motion as the output gear  52  is rotated in either a clockwise or counterclockwise motion. The rate of travel and the ratio of mechanical advantage are dependent upon the shape of the slot  98 , position of the slot  98 , and the position of the bearing  76 . In this embodiment, the pinion gear  46  is directly in mesh with the output gear  52 . 
         [0033]    In the first position, shown in  FIG. 5   a,  the bearing  76  it located at one end of the guide slot  98 . As the output gear  52  rotates, the bearing  76  moves through the guide slot  98  and moves about the axis of the output gear  52 . As the output gear  52  continues to rotate, the guide slot  98 , valve stem  72  and poppet valve  74  arrive in the position shown in  5   b.  This embodiment is also not limited for use with a poppet valve  74 , it is within the scope of the present invention to use the present invention in other devices that require rotary to axial motion. 
         [0034]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.