Patent Publication Number: US-7222598-B2

Title: Valve timing controller

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is based on Japanese Patent Application No. 2004-379125 filed on Dec. 28, 2004, the disclosure of which is incorporated herein by reference. 
   FIELD OF THE INVENTION 
   The present invention relates to a valve timing controller that adjusts valve opening/closing timing of an intake valve and/or an exhaust valve of an internal combustion engine. 
   BACKGROUND OF THE INVENTION 
   JP-8-121122A shows a valve timing controller that is provided with a housing receiving a driving force from an crankshaft of the engine and a vane rotor accommodated in the housing to transfer the driving force to a camshaft. The vane rotor rotates in advance direction and retard direction to adjust an angle phase of the camshaft relative to the crankshaft. A cylindrical member is press-fitted into the vane rotor on one end surface thereof. The housing includes a front end plate that has a boss rotatably supporting the cylindrical member. 
   As shown in  FIG. 5A , when the cylindrical member  210  is press-fitted into the receiving hole  220  of the vane rotor  200 , an inner periphery of the receiving hole  220  is expanded so that the vane rotor  200  is warped in the axial direction as shown by arrows in  FIG. 5B . This may causes a leakage of operating fluid between an advance chamber and a retard chamber. 
   SUMMARY OF THE INVENTION 
   The present invention is made in view of the foregoing matter and it is an object of the present invention to provide a valve timing controller capable of restricting a warping of the vane rotor. 
   According to the valve timing controller of the present invention, a press-fitting member and a bush are press-fitted into the vane rotor in its axial direction from opposite side surfaces respectively. Thus, the warping of the vane rotor due to the press-fitting member is cancelled by press-fitting the bush into the vane rotor. A clearance generated between the both sides of vane rotor and the inner surface of the housing is diminished so that the leakage of the operating fluid is reduced to enhance responsiveness of the valve timing controller. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     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: 
       FIG. 1A  is a longitudinal sectional view of a valve timing controller according to a first embodiment of the present invention; 
       FIG. 1B  is a schematic view showing a sector-form-chamber divided into retard and advance chambers by a vane; 
       FIG. 2  is a front view of the valve timing controller viewed along an arrow II of  FIG. 1 ; 
       FIG. 3  is a cross sectional view showing an assembly comprised of a vane rotor, a bush, and a press-fitting member; 
       FIG. 4A  is a cross sectional view showing a situation before a bush and a press-fitting member are press-fitted into the vane rotor; 
       FIG. 4B  is a cross sectional view showing a situation after the bush and the press-fitting member are press-fitted into the vane rotor; 
       FIG. 5A  is a cross sectional view showing a situation before a bush is press-fitted into the vane rotor; and 
       FIG. 5B  is a cross sectional view showing a situation after the is press-fitted into the vane rotor; 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Embodiments of the present invention will be described hereinafter with reference to the drawings. 
   (First Embodiment) 
     FIG. 1A  is a cross sectional view of a valve timing controller  1 . The valve timing controller  1  is a hydraulic-type controller that utilizes operating oil. 
   A housing is provided with a chain sprocket  11  and a shoe housing  12 . The chain sprocket  11  is made of iron alloy and the shoe housing  12  is made of aluminum alloy. The show housing  12  includes four shows (not shown in  FIG. 1A ), an annular outer wall  13 , and a front plate  14  that are integrally formed into one piece.  FIG. 1B  shows a part of two shoes  12   a  and  12   b . The front plate  14  is arranged opposite to the chain sprocket  11  across the annular outer wall  13 . The front plate  14  corresponds to one sidewall of the housing  10  and the chain sprocket  11  corresponds to the other sidewall of the housing  10 . The chain sprocket  11  and the shoe housing  12  are fastened to each other by a bolt  20  on the same axis. The chain sprocket  11  receives a driving force from a crankshaft (not shown) and rotates in synchronization with the crankshaft. 
   A camshaft (not shown) receives the driving force of the engine through the valve timing controller  1  to open/close the intake vale. The camshaft has a predetermined phase difference relative to the chain sprocket  11 . 
   The vane rotor  16  is made of aluminum alloy. A bush  22  is press-fitted into one end surface  17  of the vane rotor  16 . An annular protrusion  25  of a press-fitting member  24  is press-fitted into the other end surface  18  of the vane rotor  16 . The other end surface  18  of the vane rotor  16  confronts the chain sprocket  11 . A bolt (not shown) fastens the camshaft, the vane rotor  16   m  the bush  22 , and the press-fitting member  24  together. 
   A positioning pin  26  is press-fitted into the vane rotor  16  and the press-fitting member  24  in order to define the relative rotational position between the vane rotor  16  and the press-fitting member  24 . The camshaft, the housing  10 , and the vane rotor  16  rotates clockwise, viewing along an arrow II in  FIG. 1A . This rotating direction is defined as an advance direction of the camshaft relative to the crankshaft hereinafter. 
   The trapezoidal shoes  12   a ,  12   b  extend inwardly from the annular outer wall  13  and are disposed at regular intervals along the annular outer wall  13 . Four sector-form-chambers  50  are defined between four shoes to receive four vanes  16   a  (three of vanes are not shown). 
   The vane rotor  16  comprises a boss portion  16   e  and four vanes  16   a  that are arranged at regular intervals along the outer surface of the boss portion  16   e . The vane rotor  16  is accommodated in the housing  10  in such a manner as to rotate relative to the housing  10 . Each of vanes  16   a  divides the sector-form-chambers  50  into a retard oil chamber  51  and an advance oil chamber  52 . An arrow in  FIG. 1B  indicates a retard direction and an advance direction of the vane rotor  16  relative to the housing  10 . 
   The bush  22  and the press-fitting member  24  are made of iron alloy and are respectively press-fitted into the end surfaces  17 ,  18 . As shown in  FIG. 1A  and  FIG. 2 , the bush  22  is rotatably supported by an inner surface  14   a  of the front plate  14 . The press-fitting member  24  is contact with an end surface of the camshaft. 
   Seal members are provided between the each of the shoes and the boss portion  16   e  and between each of vanes and the inner surface of the annular outer wall  13 . The seal members  28  are biased toward each of shoes and the inner surface of the annular outer wall  13  by a spring to restrict a leakage of the operation oil between the retard oil chamber  51  and the advance oil chamber  52 . 
   A cylindrical guide ring  30  is press-fitted into the vane  16   a . A stopper pin  32  is slidablly inserted into the guide ring  30 . A ring  34  is press-fitted in a concave portion  11   a  formed on the chain sprocket  11 . The stopper pin  32  can be engaged with the ring  34 . The stopper pin  32  and the ring  34  are tapered to be smoothly engaged with each other. A spring  36  biases the stopper pin  32  toward the ring  36 . The stopper pin  32 , the ring  34 , and the spring  36  comprise a mechanism that restricts a relative rotation of the vane rotor  16  relative to the housing  10 . 
   Pressure of oil introduced into an oil pressure chambers  40 ,  42  biases the stopper pin  32  in a direction in which the stopper pin  32  is disengaged from the ring  34 . The oil pressure chamber  40  is communicated with one of the advance oil chamber  52 , and the oil chamber  42  is communicated with one of the retard oil chamber  51 . One end portion of the stopper pin  32  can be engaged with the ring  34  when the vane rotor  16  is positioned at a predetermined position relative to the housing  10 . When the stopper pin  32  is engaged with the ring  34 , the rotational position of the vane rotor  16  relative to the housing  10  is fixed. 
   When the stopper pin  32  is disengaged from the ring  34 , the vane rotor  16  is able to rotate in the retard direction and the advance direction, receiving the operation oil into the retard chamber and the advance chamber. 
   The press-fitted structure of the bush  22  and the press-fitting member  24  to the vane rotor  16  will be described hereinafter. 
   (1) As shown in  FIG. 3 , in the case that the outer diameter of the bush  22  is expressed by “a 1 ” and the outer diameter of the press-fitting member  22  is expressed by “a 2 ”, “a 1 ” is lager than “a 2 ”.
 
a1&gt;a2
 
   (2) In the case that press-fitting depth of the bush  22  is expressed by “b 1 ” and press-fitting depth of the press-fitting member  24  is expressed by “b 2 ”, “b 2 ” is larger than “b 1 ”.
 
b1&lt;b2
 
   (3) As shown in  FIG. 4A , radial press-fitting amount of the vane rotor  16  is expressed by “c 1 ” and the radial press-fitting amount of the press-fitting member  24  is expressed by “c 2 ”, “c 1 ” is larger than “c 2 ”.
 
c1&gt;c2
 
   (4) The bush  22  is made of iron alloy of which hardness is greater than that of the press-fitting member  24 . 
   According to the above four conditions (1)–(4), the warping amount of vane rotor  16  in the case where the bush  22  is press-fitted into the vane rotor  16  is larger than that of vane rotor  16  in the case where the press-fitting member  24  is press-fitted into the vane rotor  16 . Thus, when the bush  22  and the press-fitting member  24  are press-fitted into the vane rotor  16 , the vane rotor  16  warps in a direction that the bush  22  is press-fitted as shown in  FIG. 4B . The end surface  17  of the vane rotor  16  is convex and the other end surface  18  of the vane rotor  16  is concaved. The warping directions of the vane rotor  16  are quite different from each other between when the bush  22  is press-fitted and when the press-fitting member  24  is press-fitted. The warping amount “d” of the vane rotor  16  in its axial direction is reduced rather than the case where only the bush  22  is press-fitted as shown in  FIG. 5B . 
   The sliding clearances between the end surfaces  17 ,  18 , the inner surface of the chain sprocket  11  and the inner surface of the front plate  14  are reduced. Thus, oil leakage between the retard chamber and the advance chamber through the sliding clearances are restricted, so that the responsiveness of the valve timing controller is improved. 
   Since the oil leakage is restricted, total amount of operating oil can be reduced so that the size of the oil pump can be reduced. 
   Since the end surface  17  of the vane rotor  16  is convex relative to the front end plate  14  made of aluminum alloy, a sliding contact area between the end surface  17  and the front plate  14  is decreased so that the end surface  17  of the vane rotor  16  is hardly adhered to the inner surface of the front plate  14 . 
   (Alternative Embodiment) 
   In the first embodiment, four conditions (1)–(4) are established. Alternatively, at least one of four conditions can be established. 
   The shoe housing  12  and the vane rotor  16  can be made of different material respectively. The end surface  18  of the vane rotor  16  can be made convex instead of the end surface  17 . The annular outer wall  13  and the front plate  14  can be made independently. 
   In the first embodiment, driving force of the crankshaft is transmitted to the camshaft through the chain sprocket. Alternatively, a timing pulley or a timing gear can be used. 
   The stopper pin  32  can be structured is such a manner as to radially move to engage the ring  34 . Alternatively, the stopper pin  32 , the ring  34 , and the spring  36  can be omitted.