Abstract:
A grille shutter for a vehicle includes a frame, an actuator, a grille flap, and a grille shaft. The actuator includes a casing mounted on the frame, an electric motor received in the casing, an output member having a first end, a second end and a stop projection between the first and second ends, and stop members stationary relative to the casing. The stop members cooperate with the stop projection to limit rotation of the output member. The grille shaft is coupled to the output member and rotatably couples the grille flap to the frame.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This non-provisional patent application claims priority under 35 U.S.C. §119(a) from Patent Application No. 1317328.1 filed in The United Kingdom on Oct. 1, 2013, the entire contents of which are hereby incorporated by reference. 
       FIELD OF THE INVENTION 
       [0002]    This invention relates to a grille shutter for a vehicle and in particular, to a grille shutter having a limited range of motion. 
       BACKGROUND OF THE INVENTION 
       [0003]    Grilles are widely used in vehicles to allow air to enter for engine cooling. A vehicle grille is typically located at the front of the engine compartment of the vehicle. Grille shutters are used to control air flow through the grilles. Grille shutters can improve the overall fuel efficiency of a vehicle.  FIGS. 1 and 2  illustrate a traditional vehicle grille shutter  10  that includes a frame  12  and a plurality of grille flaps  14  rotatably supported by the frame  12 . The grille flaps  14  are linked together by a linkage  16  and driven by a input mechanism  18  to rotate between a fully closed position (as shown in  FIG. 1 ) and a fully open position (as shown in  FIG. 2 ). The input mechanism  18  mates with an output of an actuator. When the grille flaps  14  are in partially or fully open position, openings  20  between adjacent flaps  14  allows air to flow there through to cool the radiator and the engine of the vehicle. When the grille flaps  14  are in the fully closed position, the openings  20  are closed and outside air is blocked by the flaps  14  in order to improve fuel efficiency when the vehicle is in motion or at a temperature below a threshold value. 
         [0004]    A pair of stop projections  22  are formed on the frame  12 . When the flaps  14  rotate to the fully closed position, as shown in  FIG. 1 , further rotation of the flaps  14  is stopped by contact between adjacent flaps  14 . When the flaps  14  rotate to the fully open position, as shown in  FIG. 2 , further rotation of the flaps  14  is stopped by contact between the stop projections  22  and at least one of the flaps. 
         [0005]    In such a vehicle grille shutter arrangement, the stopping system is external to the actuator and the actuator torque stresses the mechanical parts of the grille shutter, including the stop projections, the flap and the linkage. The stresses could deform or even break the grille flaps. To avoid this problem, the mechanical parts are required to be made of a strong material. However, this makes the grille shutter heavier and less cost efficient. In addition, the external stopping system brings spatial constraints to the mechanical parts outside the actuator. 
       SUMMARY OF THE INVENTION 
       [0006]    Hence, there is a desire for an improved grille shutter that can overcome the above described shortcomings. Specifically, it is desirable to have a lighter grille shutter. 
         [0007]    Accordingly, in one aspect thereof, the present invention provides a grille shutter, comprising: a frame; an actuator comprising: a casing mounted on the frame; an electric motor disposed in the casing; and an output member driven by the electric motor and having a first end and a second end; a grille flap; and a grille shaft coupled to the output member and rotatably coupling the grille flap to the frame, wherein the actuator has a first member stationary with respect to the casing and the output member has a first projection disposed between the first and second ends and cooperating with the first member to limit rotation of the output member in a first direction. 
         [0008]    Preferably, the actuator further comprises a second member stationary with respect to the casing, the second member cooperating with the first projection to limit rotation of the output member in a second direction. 
         [0009]    Preferably, the first projection of the output member is circumferentially disposed between the first member and the second member and overlaps with the first member and the second member in a radial direction and an axial direction of the output member. 
         [0010]    Alternatively, the output member of the actuator further includes a second projection; and the first member is circumferentially disposed between the first projection and the second projection and overlaps with the first projection and the second projection in a radial direction and an axial direction of the output member. 
         [0011]    Preferably, the actuator further comprises a gear train coupling the electric motor to the output member; and the output member comprises a shaft and a plate fixed to the shaft and having a toothed segment engaged with the gear train and a smooth segment. 
         [0012]    Preferably, a maximum radius of the toothed segment is greater than a maximum radius of the smooth segment. 
         [0013]    Preferably, the first projection extends outwardly from a radially outer surface of the smooth segment. 
         [0014]    Preferably, the casing has a substantially rectangular configuration with two long side walls and two short side walls; and the smooth segment is close to and facing one of the two short side walls. 
         [0015]    Preferably, the first projection is formed on the output member and the first member is formed on the casing. 
         [0016]    According to a second aspect, the present invention provides a vehicle having a grille opening and incorporating a grille shutter as described above, wherein the frame is fixed to the vehicle and the grille shutter is arranged to substantially cover the grille opening. 
         [0017]    In embodiments of the present invention, the motion limitation system is arranged inside the actuator and mechanical parts of the grille shutter outside the actuator are not stressed by the stopping system. Therefore, the grille shutter can be made lighter. Furthermore, mechanical parts outside the actuator are not spatially constrained by the stopping system, which makes the design for these parts simpler. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    Preferred embodiments of the invention will now be described, by way of example only, with reference to figures of the accompanying drawings. In the figures, identical structures, elements or parts that appear in more than one figure are generally labeled with a same reference numeral in all the figures in which they appear. Dimensions of components and features shown in the figures are generally chosen for convenience and clarity of presentation and are not necessarily shown to scale. The figures are listed below. 
           [0019]      FIG. 1  illustrates a prior art grille shutter in the closed condition; 
           [0020]      FIG. 2  illustrates the grille shutter of  FIG. 1  in the open condition; 
           [0021]      FIG. 3  illustrates an assembled actuator in accordance with an embodiment of the present invention; 
           [0022]      FIG. 4  illustrates a grille shutter in the open condition incorporating the actuator of  FIG. 3  with some parts of the actuator removed; 
           [0023]      FIG. 5  illustrates the grille shutter and actuator of  FIG. 4 , in the closed condition; 
           [0024]      FIG. 6  is a partially enlarged view of the part actuator shown in  FIG. 4 ; 
           [0025]      FIG. 7  is a partially exploded view of the part actuator shown in  FIG. 4 ; 
           [0026]      FIG. 8  is a view of an output member being a part of the actuator of  FIG. 4 ; 
           [0027]      FIG. 9  is a plan view of the output member of  FIG. 8 ; 
           [0028]      FIG. 10  is a schematic view of a motion limitation system of a grille shutter in accordance with an embodiment of the present invention; 
           [0029]      FIG. 11  is a schematic view of a motion limitation system of a grille shutter in accordance with another embodiment of the present invention; and 
           [0030]      FIG. 12  is a plan view of the actuator of  FIG. 3  with the cover removed. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0031]      FIG. 3  illustrates an actuator  30  in accordance with a preferred embodiment of the present invention.  FIGS. 4 and 5  illustrate a grille shutter  32  for a vehicle incorporating the actuator  30  with some parts of the actuator being removed for clarity of illustration, such as the cover, motor and gear train.  FIG. 4  shows the grille shutter  32  in the fully open position and  FIG. 5  shows the grille shutter  32  in the fully closed position.  FIG. 6  is a partially enlarged view of a part of the actuator  30 . The grille shutter  32  includes a frame  34  mountable to a body of the vehicle (not shown in the figures), a plurality of grille flaps  36 , and the actuator  30 . Each of the flaps  36  has a shaft  38  rotatably supported by the frame  34 . The flaps  36  are linked together by a linkage  40 . The actuator  30  is coupled to the shaft  38  of one of the flaps  36  so as to bi-directionally rotate the flaps  36  between the fully open position and the fully closed position. 
         [0032]      FIG. 7  is an exploded view of parts of the actuator  30 . The actuator  30  includes a casing  31  (shown in  FIG. 3 ), an electric motor (not shown), an output member  42 , and a gear train (not shown) connecting the motor to the to the output member  42 . The gear train is a gear reduction transmission used to reduce the rotational speed of the motor. The motor and the gear train are received in the casing  31  and may be any type of motor and gear reduction transmission suitable for operation of the grille shutter  32 . The casing  31  comprises a base  44  fixedly mounted to the frame  34  and a cover  46  (shown in  FIG. 3 ) fixed to the base  44 . The casing  31  has a substantially rectangular configuration with two long side walls  47 ,  48  and two short side walls  49 ,  50 . The output member  42  is near one end of the rectangular casing  31  close to the short side wall  49 . Two extending parts  43 ,  45  extend inward from the long side walls  47 ,  48  so that a pair of stop members  51 ,  52  are formed adjacent to the short side wall  49 . Preferably, the stop members  51 ,  52  have two planar walls which form an angle β ( FIG. 6 ) with respect to each other. Angle β is typically between  90  and  120  degrees, depending on the application&#39;s requirement. 
         [0033]    Also referring to  FIGS. 8 and 9 , the output member  42  comprises a shaft  54  rotatably supported by the casing  31  at both ends thereof and a plate  56  attached to the shaft  54 . The shaft  54  and the plate  56  may be integrally formed as one piece or made up of separate pieces assembled together. The plate  56  has a toothed segment  58  with a plurality of teeth  60  formed on the radially outer surface thereof and a smooth segment  62 . In operation, the toothed segment  58  is engaged with a final-stage gear of the gear train. A stop projection  64  extends radially from the smooth segment  62  and the shaft  54  beyond a radially outer surface of the smooth segment  62 . In accordance with a specific embodiment of the present invention, the stop projection  64  is arranged near the circumferential center of the smooth segment  62 . The stop projection  64  is arranged circumferentially between the stop members  51 ,  52  of the casing  31  (shown in  FIG. 6 ) and overlapping with the stop members  51 ,  52  in the radial and axial directions of the shaft  54  so that the range of rotation of the stop projection  64  is confined between the stop members  51 ,  52 . Thus rotation of the output member  42  is limited by the projection  64  contacting member  51  in one direction and member  52  in the other direction. The range of motion of the output member corresponds to the flaps rotating between the open and closed positions. 
         [0034]    In accordance with a preferred embodiment, the maximum radius of the toothed segment  58  is greater than the radius of the smooth segment  62 . The stop projection  64  is adjacent to and faces the short side wall  49  during operation of the actuator  30 . This configuration requires less space for the output member  42  to operate and thereby enabling a compact design for the casing  31 . 
         [0035]    In accordance with a preferred embodiment, two virtual radial lines from the center of the shaft  54  to the two circumferential tips of the toothed segment  58  form an angle a that is greater than angle β. In accordance with a preferred embodiment, angle a is greater than angle β by the angular width of two or more teeth  60 . 
         [0036]    In operation, as the shaft  54  rotates, the output member  42  drives the grille flaps  36  and the stop projection  64  moves between the stop members  51 ,  52 . When the stop projection  64  abuts against the stop member  51 , further movement of the output member  42  and the counter-clockwise rotation of flaps  36  are stopped and the flaps  36  reach the fully open position. Outside air can be drawn into the vehicle via the openings  66  between flaps  36  with minimum obstruction to cool the radiator and the engine of the vehicle. When the stop projection  64  abuts against the stop member  52 , further movement of the output member  42  and the clockwise rotation of the flaps  36  are stopped and the flaps  36  reach a fully closed position so that the openings  66  are closed. Outside air is blocked by the flaps  36 . The output member  42  can also stop at an intermediate position when the stop projection  64  is between the stop members  51 ,  52  so that the flaps  36  are in a partially open position to provide appropriate air flow. 
         [0037]    In accordance with the present invention, the motion limitation system for confining the movement of the grille shutters is inside the actuator  30 . There is no force applied on the shutters  36 , thereby minimizing or substantially eliminating the stress on mechanical parts of the grille shutter  32  outside the actuator  30 . Therefore, the mechanical parts in grille shutter  32  can be made of lighter and/or more cost efficient material. Furthermore, there is no external spatial constraint to the motion of the mechanical parts outside the actuator  30 , which makes the design for these parts simpler. 
         [0038]    In accordance with alternative embodiments of the present invention, the stop projection  64  may alternatively be formed on another suitable rotatable member of the actuator  30  and mechanically coupled to the shaft  54 , as long as the abutment between the stop projection  64  and the stop members  52 ,  52  does not interfere with the operation of the actuator  30 . 
         [0039]    For example, the stop protrusion  64  may extend from only the shaft  54  or from only the smooth segment  62 . 
         [0040]    For example, the stop protrusion  64  may be axially aligned with or higher than the axial end surface of the plate  56  facing the cover  46 . 
         [0041]    For example, in another embodiment as shown in  FIG. 10 , the stop projection  64  is formed on an axial end (top or bottom) surface of the plate  56  and the stop members  51 ,  52  are formed on the surface of the casing  31  facing the top or bottom surface. In this embodiment, the plate  56  may be the same as the above described plate  56  and the stop projection  64  may be formed on the smooth segment  62  as shown in  FIG. 10 . Stop projection  64  may also be formed on the toothed segment  58 . The plate  56  may alternatively be a toothed wheel with teeth arranged on the entire circumference thereof. 
         [0042]    In a third embodiment, as shown in  FIG. 11 , a pair of stop projections  64 ,  65  are formed on the output member  42  and a single stop member  51  is correspondingly formed on the casing  31 . The stop member  51  is arranged circumferentially between the two stopping projections  64 ,  65  and overlapping with the stop projections  64 ,  65  in radial and axial directions. 
         [0043]    In accordance with yet another embodiment, the actuator  30  has a single stop member  51 . When the stop projection  64  abuts against the stop member  51 , further movement of the output member  42  and the counter-clockwise rotation of the flaps  36  are stopped and the flaps  36  reach a fully open position. When the flaps  36  reversely rotate and reach the fully closed position, further rotation of the flaps  36  are stopped by direct contact between adjacent flaps  36 . 
         [0044]    It should be understood that the stop members may be formed by other suitable structures which could stop rotation of the output member  42  by contacting the stop projection. 
         [0045]      FIG. 12  illustrates the actuator  30  of  FIG. 3  with the cover removed to show the motor  70  and the gear train  74  coupling the motor to the output member  42  inside the casing  31 . The motor has a worm  72  fitted to the shaft of the motor which is in mesh with a worm gear being the first gear of the gear train  74 . The final stage gear  76  is in mesh with and drives the tooth segment  56  of the output member  42 . The output member has a shaped through hole  66  for receiving the shaft or input member of the flap. A connector  80  is formed on the casing to provide an electrical connection for the motor. 
         [0046]    In the description and claims of the present application, each of the verbs “comprise”, “include”, “contain” and “have”, and variations thereof, are used in an inclusive sense, to specify the presence of the stated item or feature but do not preclude the presence of additional items or features. 
         [0047]    It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. 
         [0048]    The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined by the appended claims.