Abstract:
A driving force transmitter includes a housing rotating with the driving shaft, a transmitting member rotating with the driving shaft; and a torsion coil spring having a first end engaged with the housing and a second end engaged with the transmitting member. The spring biases the transmitting member in an advance direction or a retard direction relative to the housing. The housing includes an opening confronting the transmitting member. The transmitting member includes a projecting portion rotatably supported by the opening. An intersection point of a rotational center axis of the transmitting member and a line passing through an engaging point of the first end of the biasing member and substantially vertically intersecting the rotational center axis is positioned in a range corresponding to a width in which the projecting portion is supported by the opening.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is based on Japanese Patent Applications No. 2005-121309 filed on Apr. 19, 2005, the disclosure of which is incorporated herein by reference.  
       FIELD OF THE INVENTION  
       [0002]     The present invention relates to a driving force transmitter transmitting a driving force from a driving shaft to a driven shaft, and a valve timing controller for internal combustion engine provided with the driving force transmitter.  
       BACKGROUND OF THE INVENTION  
       [0003]     JP-2004-300930A shows a valve timing controller which is provided in a driving force transmitting system in which a driving force is transmitted from a crankshaft of the internal combustion engine to a camshaft driving an intake valve and/or an exhaust valve. The valve timing controller adjusts the intake valve and/or the exhaust valve timing  
         [0004]     As shown in  FIG. 5 , the valve timing controller includes a housing  300  rotating with the crankshaft, a vane rotor  200  rotating with a camshaft  900  and accommodated in the housing  300 , and a coil spring  600  biasing the vane rotor  200  in an advance direction or a retard direction with respect to the housing  300 . A space is formed between an inner surface of the housing  300  and the vane rotor  200 . The space is divided into a plurality of chambers by the vane rotor  200 . The chambers are filled with oil. A rotational phase between the housing  300  and the vane rotor  200  is adjusted by adjusting pressure in the chambers, whereby opening/closing timing of the intake valve and/or the exhaust valve is adjusted.  
         [0005]     A through hole  330  is provided in the housing  300  to support a projecting portion  700  of the vane rotor  200 . A torsion coil spring  600  is accommodated in the projecting portion  700 . One end of the torsion coil spring  600  is engaged with a pin  800  (point “A”) provided on an outer surface of the housing  300 , and the other end of the torsion coil spring  600  is engaged with a bottom surface of the projecting portion  700 .  
         [0006]     When a biasing force of the torsion coil spring  600  is applied to the housing  300  and the vane rotor  200 , a force shown by an arrow “F 1 ” is applied to the housing  300 , so that a rotational moment “M” is generated in a direction that the housing  300  is tilted with respect to a rotational center axis of the vane rotor  200 .  
         [0007]     The rotational moment “M” tilts the housing  300  around a corner portion (point “B”), so that the inner surface of the housing  300  is press-fitted into an outer surface of the vane rotor  200 . In this situation, when the rotational phase between the housing  300  and the vane rotor  200  is adjusted, it may be possible that a bonding is generated by a friction heat between the housing  300  and the vane rotor  200  at a place where both of them are press-fitted (an area “E” surrounded by a dashed line in  FIG. 5 ). Since the housing  300  and the vane rotor  200  are made of aluminum alloy, the boding between them is easily generated.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention is made in view of the foregoing matter and it is an object of the present invention to provide a driving force transmitter and a valve timing controller using the same, which is capable of restricting the boding therebetween even if a biasing force is applied to a housing and a vane rotor.  
         [0009]     According to a start controller of the present invention, a driving force transmitter includes a housing rotating with the driving shaft, a transmitting member rotating with the driving shaft; and a torsion coil spring having a first end engaged with the housing and a second end engaged with the transmitting member. The spring biases the transmitting member in an advance direction or a retard direction relative to the housing. The housing includes an opening confronting the transmitting member. The transmitting member includes a projecting portion rotatably supported by the opening. An intersection point of a rotational center axis of the transmitting member and a line passing through an engaging point of the first end of the biasing member and substantially vertically intersecting the rotational center axis is positioned in a range corresponding to a width in which the projecting portion is supported by the opening. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings, in which like parts are designated by like reference number and in which:  
         [0011]      FIG. 1  is a longitudinal section view of a valve timing controller for an internal combustion engine;  
         [0012]      FIG. 2  is a transverse cross section view of the valve timing controller;  
         [0013]      FIG. 3  is a front view of the valve timing controller;  
         [0014]      FIG. 4  is a partially cross sectional side view for explaining force generated on the valve timing controller; and  
         [0015]      FIG. 5  is a partially cross sectional side view for explaining force generated on a conventional valve timing controller. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]     Embodiments of the present invention will be described hereinafter with reference to the drawings.  
         [0017]     A valve timing controller  10  includes a shoe housing  1  which is driven by a crankshaft (driving shaft) through a timing belt (not shown), and a vane rotor  2  (transmitting member) which is accommodated in the shoe housing  1  coaxially. The vane rotor  2  is made of aluminum alloy (for example, aluminum alloy including magnesium and silicon), and is driven by the shoe housing  1  to transmit torque to a camshaft  9  (driven shaft). At this moment, the vane rotor  2  rotates relative to the shoe housing  1  to rotate the camshaft  9  in an advance direction or a retard direction.  
         [0018]     The shoe housing  1  includes a housing body  3 , a sprocket wheel  4 , and a plurality of bolts  11  which connect the housing body  3  and the sprocket  4  coaxially. The housing body  3  is made of aluminum alloy and includes an annular front plate  31  and a cylindrical body portion  32 . The front plate  31  is provided with a cylinder portion  34  having a center opening  33 . The cylinder portion  34  is projected from the front plate  31 . The front plate  31  is provide with a pin-engaging hole  35   
         [0019]     The body portion  32  includes four grooves  36  at an outer periphery thereof. The grooves  36  are provided at regular intervals. The body portion  32  includes four convex portions  37  at an inner periphery thereof. The convex portions  37  are respectively formed at positions corresponding to the grooves  36 . The convex portions  37  are integrated with the front plate  31  and are provided with an internal thread hole  38  in an axial direction. As shown in  FIG. 2 , four concave portions  5  are formed between adjacent convex portions  37 . Each convex portion  37  has a circular sliding surface  39  at a center side thereof. Each circular sliding surface  39  is arranged in such a manner as to be positioned in a single circle. A circular sliding surface  51  is respectively formed at the outer periphery of each concave portion  5 . Each circular sliding surface  51  is arranged in such a manner as to be positioned in a single circle.  
         [0020]     The sprocket wheel  4  has sprocket teeth  41  at the outer periphery thereof, and includes a sliding hole  42  on which the camshaft  9  slidably rotates. Through-holes  43  are formed between the sprocket teeth  41  and the sliding hole  42 . A plurality of bolts  11  are engaged with the internal thread holes  38  through the through-holes  43  to fasten the housing body  3  and the sprocket wheel  4  together. The shoe housing  1  rotates in a clockwise direction in  FIG. 2  in synchronization with the crankshaft through a timing chain (not shown) engaged with the sprocket wheel  4 . The clockwise direction is referred to as an advance direction hereinafter.  
         [0021]     The vane rotor  2  is connected with the camshaft  9  by means of a bolt  12 . The vane rotor  2  is provided with four vanes  21  which divide four concave portions  5  into an advance chamber  5   a  and a retard chamber  5   b  respectively. The vane rotor  2  is capable of rotating in a predetermined angle range with respect to the shoe housing  1 . When the advance chamber  5   a  receives operating oil therein, the vane  21  is rotated in the advance direction. When the retard chamber  5   b  receives the operating oil therein, the vane  21  is rotated in the retard direction.  
         [0022]     The front plate  31 , the body portion  32 , the sprocket wheel  4 , and the vane rotor  2  define the advance chamber  5   a  and the retard chamber  5   b  therein. These chambers  5   a,    5   b  are fluidly sealed by means of the sliding surfaces  51 , seal members  22 , the sliding surfaces  39 , and seal members  23 .  
         [0023]     The valve timing controller  10  has a differential pressure generating means (not shown) which supplies working fluid (oil) into the advance chamber  5   a  and the retard chamber  5   b  to generate a differential pressure therebetween. The differential pressure generating means includes an oil pump, a plurality of switching valves switching the oil pump between the advance chamber  5   a  and the retard chamber  5   b,  and an electromagnetic actuator driving the switching valves, and a controller controlling the actuator. The controller controls the differential pressure generating means in such a manner that the differential pressure is generated according to an engine driving condition, such as a crank angle, and engine speed, an accelerator position. This differential pressure makes a relative rotation between the vane rotor  2  and the shoe housing  1 .  
         [0024]     A stopper pin  24  is inserted to one of the vanes  21  in order to fix a preliminary position of the vane rotor  2  for starting the engine. The preliminary position is, for example, the most advance position. The stopper pin  24  is inserted in a through-hole  25  which penetrates the vane  21 , and is biased rearward by means of a compressed coil spring  26 . When the one end of the stopper pin  24  is engaged with a stopper hole  44  provided in the sprocket wheel  4 , the position of the vane rotor  2  is locked with respect to the she housing  1 .  
         [0025]     The stopper pin  24  has a step portion  27  in order to move the stopper pin  24  forward. The step portion  27  communicates with the advance chamber  5   a.  When the oil having a predetermined pressure is supplied to the advance chamber  5   a,  the stopper pin  24  receives the pressure at the step portion  27 , so that the stopper pin  24  moves to be disengaged with the stopper hole  44  against a biasing force of the compressed coil spring  26 . The rear end of the stopper pin  24  communicates with the retard chamber  5   b.  When the oil having a predetermined pressure is supplied to the retard chamber  5   b,  the stopper pin  24  moves to be disengaged with the stopper hole  44  against the biasing force of the compressed coil spring  26 .  
         [0026]     As shown in FIGS.  1  to  3 , a torsion coil spring (assist spring)  6  is provided between the shoe housing  1  and the vane rotor  2  to bias the vane rotor  2  in the advance direction. The assist spring  6  has a first elongated portion  61  and a second elongated portion  62  at both ends thereof respectively. The first elongated portion  61  is engaged with the show housing  1  or a member rotating with the shoe housing  1  together. The second elongated portion  62  is engaged with the vane rotor  2  or a member rotating with the vane rotor  2  together.  
         [0027]     A bushing  7  is provided in a cylindrical concave portion  60  formed in a center portion of the vane rotor  2 . The bushing  7  includes a circular cylinder portion  71  and a boss portion  72 . The bushing  7  prevents the assist spring  6  from interfering with the housing body  3  or the vane rotor  2 . The boss portion  72  has a bolt hole  73  through which the bolt  12  is inserted. The circular cylinder portion  71  substantially accommodates the assist spring  6 . As shown in  FIG. 1 , an axial length of the cylinder portion  34  is the same as the axial length of the circular cylinder portion  71 . The center opening  33  of the cylinder portion  34  supports an outer surface of the circular cylinder portion  71 .  
         [0028]     An engaging pin  8  is press-fitted into the pin-engaging hole  35 . The first elongated portion  61  of the assist spring  6  is engaged with the engaging pin  8 . The first elongated portion  61  passes through a clearance  63  provided in the circular cylinder portion  71 . The circular cylinder portion  71  is provided with a spring-end groove  74  which corresponds to a relative rotational angel (about 90° in this embodiment) between the vane rotor  2  and the shoe housing  1 . The cylinder portion  34  of the shoe housing  1  has a spring-end groove  40  of which shape is substantially the same as the spring-end groove  74 . The second elongated portion  62  of the assist spring  6  is engaged with a radial groove  75  which is formed in the boss portion  72  of the bushing  7 .  
         [0029]     Referring to  FIG. 4 , a generating force on the housing body  3  in a case where the assist spring  6  biases the vane rotor  2  in the advance direction will be described.  FIG. 4  is a partially cross sectional side view viewing  FIG. 1  from above.  
         [0030]     When the assist spring  6  biases the vane rotor  2  in the advance direction, a force “F 1 ” is applied to a point “A” of the engaging pin  8  provided in the front plate  31 . The point “A” corresponds to an engaging point. When the upward force “F 1 ” is applied to the point “A”, an inner surface of the center opening  33  is press-fitted to the outer surface of the bushing  7  between a point “B” and a point “C”.  
         [0031]     The positions of the points “A”, “B”, and “C” have a following relation. Intersecting points between the rotational center axis “D” of the vane rotor  2  and a plane including the points “A”, “B”, and “C” are referred to as points “A 1 ”, “B 1 ”, and “C 1 ”. As shown in  FIG. 4 , the point “A 1 ” is substantially consistent with the point “B 1 ”, so that the rotational moment “M” is not generated or the rotational moment “M” is decreased unlike the conventional apparatus shown in  FIG. 5 . Thereby, the force biasing the inner surface of the front plate  31  into a side surface of the vane rotor  2  is disappeared or diminished to restrict the boding between the housing body  3  and the vane rotor  2  due to the friction heat in the area “E” shown by dashed line.  
         [0032]     In the present embodiment, the point “A 1 ” and the point “B 1 ” are consistent with each other. At least when the point “A 1 ” is positioned between the point “B 1 ” and the point “C 1 ”, the rotational moment “M” on the housing body  3  is not generated or is reduced. Thus, the bonding between the housing body  3  and the vane rotor  2  is restricted.  
         [0033]     Since the first elongated portion  61  is engaged with a engaging pin  8  provided on the outer surface of the front plate  31 , an additional function can be added between the housing body  3  and the vane rotor  2  other than a driving force transmitting function.  
         [0034]     The rotational phase between the shoe housing  1  and the vane rotor  2  can be flexibly adjusted by controlling the hydraulic pressure in the chambers  5   a,    5   b.  The valve timing of the intake valve and/or the exhaust valve can be suitably adjusted.