Abstract:
A valve timing adjusting apparatus comprises: a housing 31 integrally provided to a timing pulley driven by an engine crank shaft, a shoe hosing 33 which is connected to the housing 31 and having a plurality of shoes 33a protruded from the inner surface of housing, and a rotor 34 which is rotatably accommodated in the she housing 33, wherein a plurality of vanes protrudedly provided on the external surface of the rotor divide the space made by the plurality of shoes 33a into an angle-delay hydraulic cabin and an angle-advance hydraulic cabin, and the rotor 34 is coaxially connectable to the camshaft 2. The valve timing adjusting apparatus further comprises: a protruded portion 46 protruding in the axial direction of the housing 31 on either one of the abutting surfaces of the rotor 34 and the housing 31, and a recess 47 to be fitted to the protruded portion 46 is formed in the other of the rotor 34 and the housing 31.

Description:
CROSS-REFERENCE TO THE RELATED APPLICATION  
       [0001]    This Application is a continuation of International Application No. PCT/JP99/05864, whose international filing date is Oct. 22, 1999, the disclosures of which Application are incorporated by reference herein, and which International Application was not published in English. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a valve timing adjusting apparatus, which variably controls the timing for opening and/or closing either an intake valve or an exhaust valve in accordance with the driving state of an internal combustion engine.  
           [0004]    2. Description of the Related Art  
           [0005]    There have been proposed various vane-type valve timing adjusting apparatuses for internal combustion engine so far, a case in point being the one disclosed in Japanese Patent Application Laid-Open No. 9-60507.  
           [0006]    [0006]FIGS. 1 and 2 are illustrations showing a conventional vane-type valve timing adjusting apparatus for internal combustion engine, which is mounted onto a camshaft of an internal combustion engine (hereinafter may be referred to just as an “engine”), wherein FIG. 1 is a longitudinal sectional view of the valve-timing adjusting apparatus, and FIG. 2 is a sectional view observed along the line II-II of FIG. 1. In FIG. 1, reference numeral  1  denotes a chain sprocket, which receives a rotational force transmitted from a crank shaft (not shown) functioning as a drive shaft of the engine by way of a chain (not shown), and rotates in synchronism with the crank shaft. The camshaft  2  functioning as a slave shaft receives the driven force transmitted from the chain sprocket  1 , and opens and/or closes at least one of an intake valve (not shown) and an exhaust valve (not shown). The camshaft  2  is rotatable with respect to the chain sprocket  1  within a predetermined angle.  
           [0007]    As shown in FIG. 1, the chain sprocket  1  and a shoe housing  3  functioning as a housing member, and also a front plate  4  functioning as a covering member are coaxially fixed by a bolt  5 . The inner surface of the boss la of the chain sprocket  1  is engaged with the end portion  2   a  of the camshaft  2  in a relatively rotatable manner. The position of the shoe housing  3  and that of the front plate  4  in the rotational angular direction are predetermined by a knock pin  6 , whereas the position of the chain sprocket  1  and that of the shoe housing  3  in the rotational angular direction are predetermined by another knock pin (not shown).  
           [0008]    As shown in FIGS. 1 and 2, the shoe housing  3  contains trapezoidal shoes  3   a  and  3   b  facing to each other. The opposing faces of these shoes  3   a  and  3   b  are formed respectively in a sectionally circular arc shape, and in two gaps made by these shoes  3   a  and  3   b  in the circumferential direction thereof, there are formed fan shape spaces for respectively accommodating vanes  7   a  and  7   b  (later explained) of a vane rotor  7 . The vane rotor  7  is generally composed of the fan shape vanes  7   a  and  7   b  and also a support member  7   c  for supporting these vanes  7   a  and  7   b , which support member being integrally fixed to the camshaft  2  by a bolt  8 . The vanes  7   a  and  7   b  are rotatably accommodated in the fan shape spaces formed in the circumferential direction of the respective shoes  3   a  and  3   b . The in-low section  7   d  of the vane rotor  7  is coaxially engaged with the end portion  2   a  of the camshaft  2 , and the position of the vane rotor  7  and that of the camshaft  2  in the rotational angular direction thereof are predetermined by a knock pin (not shown). The cylindrical protruded portion  9  integrally fixed to the vane rotor  7  is fitted into the inner peripheral surface of the front plate  4  in a relatively rotatable manner. There are formed small clearances  10  and  11  between the external peripheral surface of the vane rotor  7  and the inner peripheral surface of the show housing  3 , wherein the vane rotor  7  and the shoe housing  3  are formed in a relatively rotatable manner. There are formed a retarding hydraulic chamber  12  between the shoe  3   a  and the vane  7   a , and a retarding hydraulic chamber  13  formed between the shoe  3   b  and the vane rotor  7   b , whereas there are formed an advancing hydraulic chamber  14  between the shoe  3   a  and the vane  7   b , and also an advancing hydraulic chamber  15  between the shoe  3   b  and the vane  7   a . Further, there are formed oil paths at the opposite axial end surfaces of the support member  7   c  of the vane rotor  7 , wherein at its abutting section against the cylindrical protruded portion  9 , an oil path  16  is provided as a groove-shape path is formed, whereas at its abutting portion against the camshaft  2 , an oil path  17  is provided as a groove-like path is formed, both shifted from each other along the respectively circumferential directions in the form of a letter “C”. The oil path  16  is connected to the retarding hydraulic chambers  12  and  13  by way of other oil paths  18  and  19 , and is further connected to an oil chamber (not shown) by way of another oil path  20 . The oil path  17  is connected to the advancing angle hydraulic chambers  14  and  15  by way of other oil paths  22  and  23 . An oil path  24  is connected to an oil path  25  formed within the camshaft  2  at the abutting portion of the support member  7   c  against the camshaft  2  in the axial direction, wherein the oil path  16  is connected to the oil path  24  at the abutting portion of the support member  7   c  against the cylindrical protruded portion  9 . The oil path  17  is connected to an oil path (not shown) formed within the camshaft  2  at the abutting portion of the support member  7   c  against the camshaft  2 .  
           [0009]    By this construction above, the camshaft  2  and the vane rotor  7  are formed such that they are coaxially and relatively rotatable with respect to all the chain sprocket  1 , the shoe housing  3  and also the front plate  4 . Specially, the vane rotor  7  maintains its coaxial position with the shoe housing  3  by suppressing the shoes  3   a  and  3   b  towards the radially external direction of the vane rotor  7  by use of a chip seal  27  attached to the groove portion  7   d  formed in the external peripheral wall of its support portion  7   c.    
           [0010]    It is to be noted that when attaching the valve timing adjusting apparatus as constructed above to the engine main body, after the above-mentioned vane rotor  7  is mounted to the shoe housing  3  and the front plate  4  in a coaxially and relatively rotatable manner, the thus formed component is transported to an engine body assembling factory as an engine component in many cases. At the time of this transport, external forces such as vibration and so on can be exerted to the components such as the above-mentioned vane rotor  7  and so on.  
           [0011]    However, in the case where such an external force as the vibration during the transport is exerted against the urging force of the chip seal  27  toward the radial direction of the above-mentioned vane rotor  7 , the coaxial position of the vane rotor  7  with respect to the shoe housing  3  and so on is erroneously shifted, thereby to cause such a problem that the mountability of the vane rotor  7  onto the camshaft  2  becomes deteriorated.  
           [0012]    The present invention has been proposed to solve the problems aforementioned, and it is an object of the present invention to provide a valve timing adjusting apparatus for internal combustion engine which is provided with a means for regulating the positional relation in the radial direction between the rotor and the housing, and also that between the rotor and the covering member.  
         SUMMARY OF THE INVENTION  
         [0013]    The valve timing adjusting apparatus according to the present invention is constructed in such a manner that it comprises: a housing integrally formed with a rotational member that is driven by a crankshaft at an engine side, a shoe case, which is connected to the housing and having a plurality of shoes protruded from the inner surface of the shoe case, and a rotor which is rotatably accommodated in the shoe case, and is formed with a plurality of vanes protruding from its external peripheral surface, which vanes dividing each of the spaces between the plurality of adjacent shoes into a first hydraulic cabin and a second hydraulic cabin, wherein the rotor is coaxially connectable with a camshaft for driving a valve of an engine system to be opened and/or shut, wherein either one of the abutting surfaces between the rotor and the housing is formed with a protruded portion projecting in the axial direction of the housing, and the other of the abutting surfaces is formed with a recess to be fitted with the protruded portion. Due to this construction, the relative movements of the rotor and the housing in the radial directions can be regulated by the fitting of the protruded portion and the recess, and thus, since the relative movements of the case and the rotor in the radial direction can also be regulated, even if an external force is applied during the transport thereof, the coaxial position of the rotor with the case can be securely maintained, and thus the mountability thereof onto the camshaft of the engine main body can be greatly improved.  
           [0014]    Further, according to the present invention, the protruded portion and the recess can be fitted in a slidable manner in the axial direction of either the rotor or the housing. Due to this construction, the fitting of the protruded portion with the recess can be greatly facilitated.  
           [0015]    Further, according to the present invention, the protruded portion is a first annular projection coaxially formed with the rotor on a first boss section which is provided at either one of the axial opposite end portions of the rotor, and the recess is formed in a covering member covering one end of the axial opposite end portions and slidably fitted with the first annular projection, which recess being a first through hole coaxial with the covering member. Due to this construction, the relative movements of the covering member and the rotor in the radial direction are regulated by the fitting of the first through hole with the first annular protruded portion, and since the positional relation of the casing connected to the covering member and the rotor is regulated in the radial direction, even if an external force is applied thereto during the transport thereof, the coaxial position of the rotor with respect to the casing member can be maintained, and thus the mountability thereof onto the camshaft of the engine main body side can be greatly improved.  
           [0016]    Still further, according to the present invention, the protruded portion further contains a second annular projection coaxially formed with the rotor on a second boss section which is provided at the other end of the axial opposite end portions, and the recess further contains a second through hole coaxially formed in the housing, and silidablly fitted with the second annular projection. Due to this construction, in addition to the regulation of the positional relation between the casing and the rotor, the movement of the rotor and the housing in the radial direction can also be regulated by fitting of the second annular protruded portion and the second through hole, so that even if an external force is applied thereto during the transport thereof, the coaxial position of the rotor with respect to the housing can be securely maintained, and thus the mountability thereof onto the camshaft of the engine main body side can be greatly improved.  
           [0017]    Yet still further, the valve timing adjusting apparatus according to the present invention is constructed in such a manner that it comprises: housing integrally formed with a rotational member that is driven by a crankshaft at an engine side, a shoe case, which is connected to the housing and having a plurality of shoes protruded from the inner surface of the shoe case, and a rotor which is rotatably accommodated in the shoe case, and is formed with a plurality of vanes protruding from its external peripheral surface, which vanes dividing each of the spaces between the plurality of adjacent shoes into a first hydraulic cabin and a second hydraulic cabin, wherein the rotor is coaxially connectable with a camshaft for driving a valve of an engine system to be opened and/or shut, a covering member for covering either one of the opposite axial ends of the rotor, and a bias means, which is disposed at the opposite side of the rotor and the shoe case with respect to the covering member, and urges the rotor against the shoe case either in the advancing direction or the retarding direction, wherein either one of the abutting surfaces between the rotor and the housing is formed with a protruded portion projecting in the axial direction of the housing, and the other of the abutting surfaces is formed with a recess to be fitted with the protruded portion, wherein one part of the protruded portion is a fixed end of the bias means. Due to this construction, the relative movements of the rotor and the housing in the radial directions can be regulated by the fitting of the protruded portion and the recess, whereby even if an external force is applied thereto during the transport thereof, the coaxial position of the rotor with respect to the housing can be securely maintained, and thus the mountability thereof onto the camshaft of the engine main body side can be greatly improved. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 is a longitudinal sectional view showing a conventional vane-type valve timing adjusting apparatus.  
         [0019]    [0019]FIG. 2 is a sectional view observed along the line II-II of FIG. 1.  
         [0020]    [0020]FIG. 3 is a longitudinal sectional view showing an important portion of the valve timing adjusting apparatus according to a first embodiment of the present invention.  
         [0021]    [0021]FIG. 4 is a sectional view observed along the line IV-IV of FIG. 3.  
         [0022]    [0022]FIG. 5 is a partly magnified sectional view showing the portions V 1  and V 2  of FIG. 4.  
         [0023]    [0023]FIG. 6 is a longitudinal sectional view showing an important portion of the valve timing adjusting apparatus according to a second embodiment of the present invention.  
         [0024]    [0024]FIG. 7 is a longitudinal sectional view showing an important portion of the valve timing adjusting apparatus according to a third embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]    Several embodiments for carrying out best the present invention are now explained with reference to attached drawings, in order to explain the present invention to details.  
       First Embodiment  
       [0026]    [0026]FIG. 3 is a longitudinal sectional view showing an important portion of the valve timing adjusting apparatus according to a first embodiment of the present invention. FIG. 4 is a sectional view observed along the line IV-IV of FIG. 3, and FIG. 5 is a partly magnified sectional view showing the portions V 1  and V 2  of FIG. 4. Note that as to the components of a valve timing adjusting apparatus for internal combustion engine according to the first embodiment, the same or similar members as or to those in FIGS. 1 and 2 are put the same reference numerals for omitting a repetition of the same explanation.  
         [0027]    In these figures, reference numeral  30  denotes a timing pulley as a rotating member that is driven in synchronism with the rotation of the engine by way of an endless belt (not shown), and numeral  31  denotes a housing of a substantially disk shape integrally formed with the timing pulley  30 . The center portion of the housing  31  is formed with a through hole  32  so as to be fitted with the camshaft  2  inserted therethrough. There is provided a shoe housing  33  as a casing and the vane rotor  34  accommodated in this shoe housing  33  between the housing  31  and the front plate  4 . The inner peripheral surface of the shoe housing  33  is formed with four shoes  33   a ,  33   b ,  33   c  and  33   d , whereas the external peripheral surface of the vane rotor  34  is formed with four vanes  34   a ,  34   b ,  34   c  and  34   d . In this configuration, the vane  34  is accommodated in the fan shape space between the shoes  33   a  and  33   b , the vane  34   b  is accommodated in the fan shape space between the shoes  33   b  and  33   c , the vane  34   c  is accommodated in the fan shape space between the shoes  33   c  and  33   d , and the vane  34   d  is accommodated in the fan shape space between the shoes  33   d  and  33   a , wherein the respective vanes  34   a ,  34   b ,  34   c  and  34   d  divide each of the fan shape spaces into the retarding hydraulic chamber  35  as a first hydraulic chamber and the advancing hydraulic chamber  36  as a second hydraulic chamber. The mutually adjacent retarding hydraulic chambers  35  and the advancing hydraulic chambers  36  are hampered from being interconnected by the chip seal  37  provided to each of the end portions of the shoes  33   a ,  33   b ,  33   c  and  33   d , and by the chip seal  38  provided to each of the end portions of the vanes  34   a ,  34   b ,  34   c  and  34   d . It is to be noted that reference numeral  39  denotes a back spring that makes each of the chip seals  37  to be brought into contact with the external surface of the vane rotor  34 , and a similar back spring (not shown) is provided also to each of the other chip seals  38 .  
         [0028]    In FIG. 4, numeral  40  denotes a plunger slidably disposed along the axial direction in the through hole  31   a  of the housing  31 , numeral  41  denotes a spring that is disposed in the through hole  31   a  of the housing  31 , urging the plunger  40  into the fitting hole  42  of the vane rotor  34 , and numeral  43  denotes a plunger oil path for feeding oil into the fitting hole  42  of the vane rotor  34  and/or exhausting the used oil from the fitting hole  42 . In the case where oil pressure is not supplied to this plunger oil path  43 , the plunger  40  is fitted into the fitting hole  42  of the vane rotor  34  by the urging force of the spring  41 , whereby the relative rotation of the vane rotor  34  and the housing  31  is suppressed. On the other hand, in the case where oil pressure is supplied to the plunger oil path  43 , the thus supplied oil pressure pushes the plunger  40  rearward against the urging force of the spring  41 , and the plunger  40  is separated from the fitting hole  42  of the vane rotor  34 , whereby the suppression of relative rotation of the vane rotor  34  and the housing  1  is released.  
         [0029]    Note that reference numeral  44  denotes a first oil path provided within the camshaft  2 , and is connected to the retarding hydraulic chamber  35  for shifting the vane rotor  34  in the retarding direction, whereas reference numeral  45  denotes a second oil path provided also within the camshaft  2 , and is connected to the advancing hydraulic chamber  36  for shifting the vane rotor  34  in the advancing direction.  
         [0030]    In FIG. 5, numeral  46  denotes a protruded portion coaxially formed with the vane rotor  34  on the abutting surface at which the vane rotor  34  comes into contact with the housing  31 , and projects along the axial direction of the vane rotor  34 , whereas numeral  47  denotes a recess portion that is formed coaxially with the housing  31  at the abutting side of the through hole  32  of the housing  31  at which the housing  31  comes into contact with the bane rotor  34 , and is fitted with the protruded portion  46 . The inner surface  47   a  of this recess  47  and the external surface  46   a  of the protruded portion  46  are, when the housing  31  and the vane rotor  34  are to be fitted, slidably fitted in the axial direction of the vane rotor  34 , and the vane rotor  34  and the housing  31  are relatively rotatable. Note that the front plate  4 , the shoe housing  33  and the housing  31  are integrally fixed by a bolt  5 .  
         [0031]    Further, the center portion of the protruded portion  46  of the vane rotor  34  is formed with a fixing recess  48  for receiving and fixing the end portion  2   a  of the camshaft  2 , and an opening of this fixing recess  48  is formed with a slant portion  48   a  for guiding the end portion  2   a  of the camshaft  2  when inserting the camshaft  2  thereto.  
         [0032]    Next, the method of mounting the above-explained valve-timing adjusting apparatus to the engine body is explained as below.  
         [0033]    First, the vane rotor  34  is accommodated in the shoe housing  33 , and the front plate  4  is attached to the end portion of these vane rotor  34  and shoe housing  33 . Thereafter, when attaching the vane rotor  34  to the housing  31 , the protruded portion  46  of the vane rotor  34  is fitted into the recess  47  of the housing  31  thereby to compose an engine part, and the thus composed engine part is transported to the assembling factory of the engine body. Note that the protruded portion  46  and the recess  47  are fitted in a slidable manner along the axial direction of the vane rotor  34 , and further the vane rotor  34  and the housing  31  are made relatively rotatable, although the vane rotor  34  is delimited its movement in the radial direction by this fitting operation of the protruded portion  46  and the recess  47 . Thus, even if an eternal force is exerted in the radial direction of the vane rotor  34  against the urging force of the chip seals  37  and  38  during the transport thereof, the displacement of the coaxial point of the vane rotor  34  with respect to the housing  31  can securely be prevented, so that the mountability of the vane rotor  34  onto the camshaft  2  can be greatly improved. Thereafter, at the engine body assembling factory, one end portion  2   a  of the camshaft  2  is inserted into the through hole  32  of the housing  31 . Here, the end portion  2   a  of the camshaft  2  is inserted into the recess  48  of the vane rotor  34  coaxially mounted to the housing  31 , wherein the end portion  2   a  of the camshaft  2  is securely guided into the fixing recess  48  owing to the slant portion  48   a , and is fixed to the vane rotor  34  by a bolt  49  in a coaxial manner.  
         [0034]    Next, the operation of the valve timing adjusting apparatus for internal combustion engine is now explained below.  
         [0035]    First, in the case where the camshaft  2  is to be retarded in terms of timing with respect to the rotation angle of the timing pulley  30 , oil is provided from an oil providing source (not shown) into the retarding hydraulic chambers  35  out of the two types of hydraulic chambers; namely the advancing hydraulic chambers  36  and the retarding hydraulic chambers  35 , which are dividedly formed by the vanes  34   a ,  34   b ,  34   c  and  34   d , and at the same time oil is exhausted from the advancing hydraulic chambers  36 , whereby the camshaft is rotated, taking advantage of the difference of oil pressures at the respective sides of each of the vanes  34   a ,  34   b ,  34   c  and  34   d . On this occasion, when the timing pulley  30  is rotated, the plunger  40  urged toward the camshaft  2  by the spring  41  is inserted into the fitting hole  42  of the vane rotor  34 , and thus the relative rotation between the camshaft  2  which is firmly connected to the vane rotor  34  and the timing pulley  30  is suppressed.  
         [0036]    As explained above, since it is intended according to this first embodiment that the coaxial position of the vane rotor  34  with respect to the housing  31  can be secured by fitting the protruded portion  46  provided to the vane rotor  34  in the axial direction into the recess  47  provided in the housing  31 , the mountability of the vane rotor  34  onto the camshaft  2  can be greatly improved.  
         [0037]    It should be noted that although in this embodiment the recess is formed at the housing  31  side and the protruded portion is provided at the vane rotor  34  side, the protruded portion can be provided at the housing  31  side, and the recess can be formed at the vane rotor  34  side, but on condition that the relative rotations of the housing  31  and the vane rotor  34  are not thereby delimited. Even in this case, the displacement of the coaxial point of the vane rotor  34  with respect to the housing  31  can securely be prevented, so that the mountability of the vane rotor  34  onto the camshaft  2  can be greatly improved.  
       Second Embodiment  
       [0038]    [0038]FIG. 6 is a longitudinal sectional view showing an important portion of the valve timing adjusting apparatus according to a second embodiment of the present invention. Note that the same or similar members as or to those in FIGS.  3 , at and  5  are put the same reference numerals for omitting a repetition of the same explanation.  
         [0039]    The technical feature of this second embodiment resides in that the vane rotor  34  is fitted not only with the housing  31  in the valve-timing adjusting apparatus to be attached to the air intake side of an engine, just as the first embodiment, but also fitted with the front plate at That is, the protruded portion  46  of the vane rotor  34  is largely protruded much more than the case of the first embodiment so as to be a boss section (first boss), and threads through the recess  47  of the housing  31 . The external peripheral surface  46   a  of the vane rotor  34  and the inner peripheral surface  47   a  of the recess  47  are fitted in an axially slidable manner, and the vane rotor  34  and the housing  31  are set in the relatively rotatable manner.  
         [0040]    The center portion of the vane rotor  34  is formed with a cylindrical protruded portion  50  projecting in the axial direction as a boss section (second boss) at the opposite side of the protruded portion  46 , and the center portion of the front plate at is formed with a through hole  51 . The external peripheral surface  50   a  of the protruded portion  50  and the inner peripheral surface  51   a  of the through hole  51  are slidably fitted in the axial direction of the vane rotor  34 , and the vane rotor  34  and the front plate at are formed in the relatively rotatable manner. Note that the front plate at, the shoe housing  33  and the housing  31  are integrally fixed by a bolt  5 .  
         [0041]    Due to the construction as explained above, in this second embodiment, not only the protruded portion  46  of the vane rotor  34  is fitted to the recess  47  of the housing  31 , but the protruded portion  50  of the vane rotor  34  is also fitted into the through hole  51  of the front plate at, whereby the coaxial point of the vane rotor  34  with respect to the housing  31  and the front plate at can securely be maintained.  
       Third Embodiment  
       [0042]    [0042]FIG. 7 is a longitudinal sectional view showing an important portion of the valve timing adjusting apparatus according to a third embodiment of the present invention. Note that the same or similar members as or to those of the valve timing adjusting apparatus according to the first and second embodiments as shown in FIGS.  3  to  6  are put the same reference numerals for omitting a repetition of the same explanation.  
         [0043]    The technical feature of this third embodiment resides in that in the valve-timing adjusting apparatus to be attached to the air exhausting side of an engine, two boss sections of the vane rotor  34  are fitted both with the housing  31  and a later-explained unit cover. That is, the protruded portion  46  provided at one axial end surface of the vane rotor  34  is fitted into the recess  47  of the housing  31 . Further, the other protruded portion  50  of the vane rotor  34  is fitted into the first and a second through holes  52   a  and  53   a , which are formed in the center portion of a first plate  52  attached to both the shoe housing  33  and the other axial end surface of the vane rotor  34 , and in the center portion of the second plate  53  attached to the surface of the first plate  52 , respectively in the coaxial manner. These first and second plates  52  and  53  are fixed to the housing  31  and the vane rotor  34  by a fixing bolt  54 . The outer periphery of the first plate  52  is bent to the direction opposite to the vane rotor  34  to make a bent portion  52   b , and this bent portion  52  holds the second plate  53  and the covering member  55 , sandwiching the second plate  53  between the bent portion  52  and the covering member  55 . The covering member  55  contains a third through hole  55   a  for threading therein a bolt  56  used for coaxially fixing the vane rotor  34  and the camshaft  2 , and also an accommodating section  55   b  that encloses the third through hole  55   a  therein, and also accommodates a spring as a bias means for urging the vanes  34   a ,  34   b ,  34   c  and  34   d  toward the retarding direction or advancing direction with respect to the shoe housing  33 . The spring  57  is wound around the external peripheral portion of the protruded portion  50  of the vane rotor  34  fitted both with the first through hole  52   a  of the first plate  52  and the second through hole  53   a  of the second plate  53 . The fixed end  57   a  of the spring  57  is abutted against the notched portion  50   b  of the protruded portion  50 , whereas the top end portion  50   c  of the protruded portion  50  is abutted against the inner peripheral brim of the third hole  55   a  of the covering member  55 . Note that the first plate  52 , the second plate  53  and the covering member  55  configure together a unit cover  58 . Further, In FIG. 7, reference numeral  59  denotes a holder for positioning the spring  41  that urges the plunger  40  for suppressing the relational movements of the shoe housing  33  and the vane rotor  34 .  
         [0044]    Since in this third embodiment of the present invention the protruded portion  46  of the vane rotor  34  is fitted into the recess of the housing  31 , whereas the other protruded portion  50  of the vane rotor  34  is fitted into the first through hole  52   a  of the first plate  52  and the second through hole  53   a  of the second plate  53 , there is such an effect that the coaxial position of the vane rotor  34  with respect to the housing  31  and to the unit cover  58  can be securely maintained.  
         [0045]    Further, in this third embodiment, since it is arranged such that the fixed end  57   a  of the spring  57  is abutted against the notched portion  50   b  of the protruded portion  50  of the vane rotor  34 , and the urging force of the spring  57  is applied directly to the vane rotor  34 , there is such an effect that the components at the above two fitting portions are prevented from slipping off in the axial direction.  
         [0046]    As explained heretofore, the valve timing adjusting apparatus according to the present invention is capable of maintaining the coaxial position of the rotor with respect to both the casing and the housing by delimiting the positional relation between the rotor and the housing, and that between the rotor and the covering member in the radial direction, whereby the mountability thereof onto the camshaft can be greatly improved.