Patent Publication Number: US-8978608-B2

Title: Valve timing control apparatus for internal combustion engine

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The present invention relates to a valve timing control apparatus for an internal combustion engine which controls valve open-and-closure characteristics of an intake valve(s) or an exhaust valve(s) of the internal combustion engine. 
     (2) Description of Related Art 
     Recently, a valve timing control apparatus has been proposed in which a phase modification mechanism which converts a relative rotational phase of a camshaft with respect to a sprocket to which a rotational force from a crankshaft is transmitted by transmitting a rotational force of an electrically driven motor to a camshaft which provides an output axle via a speed reduction mechanism to control open-and-closure timings of an intake valve(s) and/or an exhaust valve(s). 
     Such a valve timing control apparatus as described above is exemplified by a Japanese Patent Application First Publication No. 2011-256798 published on Dec. 22, 2011 in which a power supply to the electrically driven motor is carried out by means of an electrical contact between a brush mounted on a cover member arranged at a forward side of the phase modification mechanism and a slip ring installed at the phase modification mechanism side. 
     SUMMARY OF THE INVENTION 
     However, in the valve timing control apparatus described in the above-described Japanese Patent Application First Publication, the cover member on which the brush is mounted is fixed on a chain cover and the phase adjustment mechanism on which the slip ring is installed is rotatably supported on a bearing member installed on a cylinder head via the camshaft. 
     Therefore, at a time of an assembly of each component, a relative position of a center of a working hole disposed on the cover member and an axial center of an output axle of the electrically driven motor are matched with each other using a jig or so forth so that no positional deviations between the brush and the slip ring and between a seal member disposed on an inner periphery of the cover member and an outer periphery of the phase modification mechanism occur. Then, upon the end of the above-described matching adjustment of the relative position, it is necessary to fix the cover member to the chain cover. Therefore, a positioning work related thereto becomes complicated. 
     It is, hence, an object of the present invention to provide a valve timing control apparatus for an internal combustion engine which can facilitate the assembly work of each component described above while suppressing the positional deviation between the cover member and the phase modification mechanism. 
     According to one aspect of the present invention, there is provided a valve timing control apparatus for an internal combustion engine, comprising: a driving rotary body to which a rotational force is transmitted from a crankshaft; a driven rotary body fixed to a camshaft; an electrically driven motor fixed to the driving rotary body; a speed reduction mechanism configured to reduce a rotation of the electrically driven motor and to transmit the reduced rotation to the driven rotary body; a phase modification mechanism which is capable of modifying a relative rotational phase of the camshaft with respect to the driving rotary body in accordance with an engine state; a cover member arranged at the tip side of the phase modification mechanism and fixed to a chain cover of the internal combustion engine; a pair of inner and outer periphery slip rings disposed on either one of a tip surface of the phase modification mechanism or another tip surface of the cover member opposed to the tip surface of the phase modification mechanism to supply an electric power to the electrically driven motor; and a pair of brushes disposed on either the other of the tip surface of the phase modification mechanism or the other tip surface of the cover member and constructed to slidably contact on the respective slip rings, wherein a plurality of projection sections projected toward the cover member are integrally mounted on a bearing member configured to rotatably journalize the camshaft and a plurality of positioning pins are extended over the cover member and the respective projection sections. 
     According to another aspect of the present invention, there is provided a valve timing control apparatus for an internal combustion engine, comprising: a driving rotary body to which a rotational force is transmitted from a crankshaft; a driven rotary body fixed to a camshaft; an electrically driven motor fixed to the driving rotary body; a speed reduction mechanism configured to reduce a rotation speed of the electrically driven motor and to transmit the speed reduced rotation to the driven rotary body; a phase modification mechanism which is capable of modifying a relative rotational phase of the camshaft with respect to the driving rotary body in accordance with an engine state; a cover member arranged at a tip side of the phase modification mechanism and fixed to a side surface of the internal combustion engine; a pair of inner and outer periphery slip rings disposed on either one of a tip surface of the phase modification mechanism or another tip surface of the cover member opposed to the tip surface of the phase modification mechanism to supply an electric power to the electrically driven motor; and a pair of brushes disposed on either the other of the tip surface of to the phase modification mechanism or the other tip surface of the cover member and constructed to slidably contact on the respective slip rings, wherein the cover member is fixed to the side surface of the internal combustion engine in a state in which the cover member is positioned from a radial direction of the camshaft with respect to a rotation center of the camshaft by means of a positioning section disposed on a bearing member rotatably journaling the camshaft. 
     According to a still another aspect of the present invention, there is provided a valve timing control apparatus for an internal combustion engine, comprising: a driving rotary body to which a rotational force is transmitted from a crankshaft; a driven rotary body fixed to a camshaft; an electrically driven motor fixed to the driving rotary body; a speed reduction mechanism configured to reduce a rotation of the electrically driven motor and to transmit the reduced rotation to the driven rotary body; a phase modification mechanism which is capable of modifying a relative rotational phase of the camshaft with respect to the driving rotary body in accordance with an engine state; a cover member arranged at a tip side of the phase modification mechanism to cover at least part of the phase modification mechanism and fixed to a chain cover of the internal combustion engine; and a seal member fixed to either one of an inner periphery of the cover member and an outer periphery of the phase modification mechanism to slide on either the other of the inner periphery of the cover member and the outer periphery of the phase modification mechanism, wherein a plurality of projection sections projected toward the cover member are integrally mounted on a bearing member rotatably journaling the camshaft and positioning pins are interposed between the cover member and the respective projection sections. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a longitudinal cross sectional view representing a preferred embodiment of a valve timing control apparatus according to the present invention. 
         FIG. 2  is an exploded perspective view of main components in the preferred embodiment shown in  FIG. 1 . 
         FIG. 3  is a cross sectional view cut away along a line of A to A in  FIG. 1 . 
         FIG. 4  is a cross sectional view cut away along a line of B to B in  FIG. 1 . 
         FIG. 5  is a cross sectional view cut away along a line of C to C in  FIG. 1 . 
         FIG. 6  is an outer side view of a cover member used in the preferred embodiment shown in  FIG. 1 . 
         FIG. 7  is an inner side view of the cover member used in the preferred embodiment shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, a preferred embodiment of a valve timing control apparatus for an internal combustion engine according to the present invention will be described on a basis of the attached drawings. It should be noted that this embodiment is applicable to a variably operated valve system at an intake side of the internal combustion engine. However, the present invention is similarly applicable to the variably operated valve system at an exhaust side of the internal combustion engine. 
     This valve timing control apparatus, as shown in  FIGS. 1 and 2 , includes: a timing sprocket  1  which is a driving rotary body rotatably driven by means of a crankshaft of the internal combustion engine; a camshaft  2  rotatably journalled by means of a bearing member  42  to installed on a cylinder head to rotate a rotational force transmitted from timing sprocket  1 ; a cover member  3  fixed by means of a chain cover  49  disposed on an outside of timing sprocket  1 ; and a phase modification mechanism  4  interposed between timing sprocket  1  and camshaft  2  to is modify a relative rotational phase between timing sprocket  1  and camshaft  2  in accordance with the engine driving state. 
     A whole of timing sprocket  1  is made of an iron series metal and integrally formed in a circular shape. Timing sprocket  1  includes: a sprocket main body  1   a  having an inner peripheral surface of a step difference diameter shape; a gear section  1   b  which receives the rotational force from the crankshaft via a wound timing chain (not shown), gear section  1   b  integrally mounted on the outer periphery of sprocket main body  1   a ; and an inner teeth constituent section  19  which is an inner teeth mesh section integrally mounted on the forward end side of sprocket main body  1   a.    
     In addition, this timing sprocket  1  includes a single large diameter ball bearing  43  which is a bearing and which is intervened between sprocket main body  1   a  and a driven member  9  which is a driven rotary body as will be described later disposed on the forward end side of camshaft  2 . Timing sprocket  1  and camshaft  2  are relatively rotatably supported on this large diameter ball bearing  43 . 
     This large diameter ball bearing  43  includes: an outer wheel  43   a ; an inner wheel  43   b ; and balls  43   c  intervened between the outer and inner wheels  43   a ,  43   b . This large diameter ball bearing  43  has outer wheel  43   a  fixed onto an inner peripheral side of sprocket main body  1   a  while inner wheel  43   b  is fixed onto the outer peripheral side of sprocket main body  1   a.    
     This sprocket main body  1   a  has the inner peripheral side on which an annular shaped outer wheel fixture groove  60  opened to camshaft  2  side. 
     This outer wheel fixture groove  60  is formed in is a step difference diameter shape, has the inner peripheral surface into which outer wheel  43   a  of large diameter ball bearing  43  inserted from the axial direction, and makes a positioning in the one direction side in the axial direction of outer wheel  43   a.    
     Inner teeth constituent section  19  is integrally installed on a forward end outer peripheral side of sprocket main body  1   a  and is formed in a cylindrical shape extended in a direction of electrically driven motor  12  of phase modification mechanism  4 . A plurality of waveform shaped inner teeth  19   a  are formed on an inner periphery of inner teeth constituent section  19 . 
     Respective inner teeth  19   a , as shown in  FIGS. 1 and 3 , are continuously and plurally formed at equal intervals in a circumference direction and are constituted by mountain shaped addendum parts, both teeth surfaces continued from the addendum parts to both sides of respective inner teeth  19   a ; and bottomlands of teeth between both teeth surfaces. 
     In addition, a laser hardness process is carried out on the addendum parts and both teeth surfaces of respective inner teeth  19   a  in inner teeth constituent section  19  in the same way as gear section  1   b , a hardness of these parts being formed to be higher than parts of the respective teeth bottomlands. 
     In addition, an annular female screw forming section  6  integral with a housing  5  of electrically driven motor  12  is opposed against the forward end side of inner teeth constituent section  19 , as will be described later. 
     An annular holding plate  61  is disposed on a rear end section of sprocket  1  opposite to inner teeth constituent section  19  of sprocket main body  1   a . This holding plate  61  is integrally formed by a metallic plate material. As shown in  FIG. 1 , an outer diameter of holding plate  61  is set to be generally the same as the outer diameter of sprocket main body  1   a . In addition, an inner diameter of holding plate  61  is set to be a diameter in the vicinity to a generally center section of a diameter direction of large diameter ball bearing  43 . 
     Hence, an inner peripheral section  61   a  of holding plate  61  is opposed with a constant gap to cover an outer end surface  43   e  in an axial direction of outer wheel  43   a  of large diameter ball bearing  43 . In addition, a stopper convex section  61   b  is integrally disposed on an inner peripheral edge predetermined position of inner peripheral portion  61   a  and projected toward a center axis direction, namely, toward an inner side of the radial direction of outer wheel  43   a.    
     This stopper convex section  61   b  is, as shown in  FIG. 4 , formed in an approximately arc shape. Stopper convex section  61   b  has a tip edge  61   c  formed in an arc shape along an inner peripheral surface in the arc shape of a stopper groove  2   b  as will be described later. Furthermore, six bolt inserting holes  61   d  through which respective bolts  7  are inserted are penetrated through an outer peripheral surface in the arc shape of stopper groove  2   b  as will be described later at equal interval positions in the circumferential direction of holding plate  61 . 
     Furthermore, an annular spacer  62  is interposed between an inner surface of holding plate  61  and outer end surface  43   e  of outer wheel  43   a  of large diameter ball bearing  43  opposed against the inner surface of holding plate  61  is tightened and fixed with this spacer  62  by means of respective bolts  7 . At this time, spacer  62  provides a slight pressing force against an outer end surface  43   e  of outer wheel  43   a . A wall thickness of this spacer  62  is set to a thickness to a degree such that a minute gap is formed within an axial directional movement allowable range in the axial direction of outer wheel  43   a  between outer end surface  43   e  of outer wheel  43   a  and holding plate  61 . 
     Respective outer peripheral sections of sprocket main body  1   a  (inner teeth constituent section  19 ) and holding plate  61  have six bolt inserting holes  1   c ,  61   d  penetrated at substantially equal interval positions in the circumferential directions of sprocket main body  1   a  and holding plate  61 . In addition, female screw forming section  6  is formed with six female screw holes  6   a  at positions corresponding to respective bolt inserting holes  1   c ,  61   d . Six bolts  7  inserted into these holes allow the tightening fixture for timing sprocket  1 , holding plate  61 , and housing  5  from the axial direction of housing  5 . 
     It should be noted that sprocket main body  1   a  and inner teeth constituent section  19  are constituted by a casing of speed reduction mechanism  8  as will be described later. 
     It should be noted that respective outer diameters of sprocket main body  1   a , inner teeth constituent section  19 , holding plate  61 , and female screw forming section  6  are set to be approximately the same. 
     Chain cover  49  is disposed and fixed along a vertical direction of timing sprocket  1  to cover a chain wound on timing sprocket  1  at a forward end side of a cylinder head and a cylinder block (not shown) as shown in  FIG. 1  and an opening section  49   a  is formed on a position corresponding to phase modification mechanism  4 . Inserting holes  49   c ,  49   d  into which a pair of positioning pins  54 ,  55  as will be described later are loosely (movably) inserted are penetrated at both sides of an annular wall  49   b  constituting this opening section  49   a.    
     Cover member  3 , as shown in  FIGS. 1 ,  6 , and  7 , is integrally formed in a cup shape of an aluminum alloy material and is constituted by a swelling cover main body  3   a  and an annular attachment flange  3   b  integrally formed on an outer peripheral edge of an opening side of cover main body  3   a . Cover main body  3   a  is disposed so as to cover the forward end of housing  5  and a cylindrical wall  3   c  is integrally formed at the outer peripheral side of cover main body  3   a  along the axial direction of cover member  3 . This cylindrical wall  3   c  has an inner part on which a holding hole  3   d  is formed and the inner peripheral surface of this holding hole  3   d  constitutes a guide surface of a brush holding body  28  as will be described later. 
     Four boss sections  3   e ,  3   f  are disposed at approximately equal interval positions (about 90° interval positions) in the circumferential direction of cover member  30 . A bolt inserting hole  3   g  through which a bolt is inserted, the bolt screwed into a female screw hole not shown but is fitted into an annular wall  49   b  of chain cover  49 . Thus, cover member  3  is fixed to chain cover  49  by means of respective bolts. 
     Furthermore, in  FIG. 6 , two boss sections  3   f ,  3   f  at both of left and right sides of cover member main body  3   a  are formed to be elongated in the circumferential direction of attaching flange  3   b . In addition to respective bolt inserting holes  3   g  formed at one end section in the circumferential direction of attaching flange  3   b , two positioning pin holes  3   i ,  3   j  through which one end sections  54   a ,  55   a  of the pair of positioning pins  54 ,  55  as will be described later are inserted are formed at forward end attaching surface side of attaching flange  3   b . This one positioning pin hole  3   i  is formed in a circular shape but the other positioning pin hole  3   j  is formed in an elongate hole (eclipse) shape which is long in the diameter direction of attaching flange  3   b.    
     A substantially annular seal holding groove  3   k  is formed along a circumferential direction as shown in  FIG. 7  on an attaching surface  3   h  of attaching flange  3   b . This seal holding groove  3   k  is wholly formed in a uniform width and is formed in a substantially annular shape. However, this seal holding groove  3   k  is formed in a curved shape toward outsides of respective positioning holes  3   i ,  3   j  and a seal ring  56  is fitted and held at an inner part of seal holding groove  3   k.    
     This seal ring  56  is integrally formed of a synthetic resin rubber. This seal ring  56  has a cross section formed in a substantially circular shape. An outer diameter of seal main body  56   a  is formed to be sufficiently smaller than a groove width of seal holding groove  3   k . Six stopper projection sections  56   b ,  56   c  are integrally mounted at approximately equal interval positions in the circumferential direction of seal main body  56   a . These stopper projection sections  56   b ,  56   c  are two stopper projection sections projected toward both sides in the radial direction of seal main body  56   a , namely, projected toward an inner peripheral side and toward an outer peripheral side with seal main body  56   a  as a center. The width in the radial direction of two stopper projection sections  56   b ,  56   c  is formed to be set to be larger than the groove width of seal holding groove  3   k . Two stopper projection sections are elastically contacted on opposing surfaces of seal holding groove  3   k . Utilizing this elastically contacting force, the whole seal ring  56  is held within seal holding groove  3   k.    
     Then, seal ring  56  serves to seal between cover member  3  and chain cover  40  when cover member  3  is made contact on a forward surface of annular wall  49   b  of chain cover  49  and elastically contacted on annular wall  49   b.    
     A large diameter oil seal  50  which is a seal member is interposed between an inner peripheral surface of a step difference section of an outer peripheral side of cover main body  3   a  and an outer peripheral surface of housing  5 , as shown in  FIG. 1 . This large diameter oil seal  50  has a cross section formed in a substantially letter of a left inverted U shape. A cored bar is buried into an inside of a base material of the synthetic rubber. In addition, an annular base section  50   a  at the outer peripheral side is fitted and fixed to a step difference annular section installed on an inner peripheral surface of cover member  3 . 
     Housing  5  includes: a housing main body  5   a  which is a cylindrical section formed of an iron-series metallic material in a bottomed cylindrical shape by means of a press forming; and a sealing plate  11  made of a non-magnetic material of a synthetic resin sealing a forward end opening of housing main body  5   a.    
     A disk shaped bottom section  5   b  is provided at the rear end side of housing main body  5   a  and a large diameter axle section inserting hole  5   c  into which an eccentric axle section  39  is inserted as will be described later is formed at a substantially center of bottom section  5   b . On a hole edge of axle section inserting hole  5   c , a cylindrical extended section  5   d  projected in the axial direction of camshaft  2  is integrally formed. In addition, female screw forming section  6  is integrally formed at an outer peripheral side of a forward end surface of bottom section  5   b.    
     Camshaft  2  is provided with two drive cams per cylinder at the outer periphery of camshaft  2  which actuates intake valve(s) to open not shown. Flange section  2   a  is integrally disposed on the forward end section of camshaft  2 . 
     This flange section  2   a  has an outer diameter to be set to be slightly larger than an outer diameter of a fixture end section  9   a  of driven member  9  as will be described later, as shown in  FIG. 1 . After the assembly of each constituent member (component), the outer peripheral section of forward end surface  2   e  is contacted on the outer end surface in the axial direction of inner wheel  43   b  of large diameter ball bearing  43 . In addition, forward end surface  2   e  is coupled with driven member  9  from the axial direction by means of a cam bolt  10  in a state in which forward end surface  2   e  is axially contacted on driven member  5 . 
     A stopper recess groove  2   b  into which stopper convex section  61   b  of holing plate  61  is engageably inserted is formed along a circumferential direction of flange section  2   a , as shown in  FIG. 4 . This stopper recess groove  2   b  is formed in the arc shape of a predetermined length in the circumferential direction of flange section  2   a . Then, both end edges of stopper convex section  61   b  pivoted in this length range are respectively contacted against opposing edges  2   c ,  2   d  in the circumferential direction of camshaft  2 . Thus, a relative rotational position of camshaft  2  with respect to timing sprocket  1  at a maximum advance angle side or at a maximum retardation angle side is limited. 
     It should be noted that stopper convex section  61   b  is spaced apart toward camshaft side  2  than a position of holding plate  61  opposed and fixed to outer wheel  43   a  of large diameter ball bearing  43  of holding plate from the outside of axial direction of outer wheel  43   a  so as to be in a non-contact state against fixture end section  9   a  of driven member  9 . Hence, an interference between stopper convex section  61   b  and fixture end section  9   a  can sufficiently be suppressed. 
     A stopper mechanism is constituted by stopper convex section  61   b  and stopper recess groove  2   b.    
     As shown in  FIG. 1 , bearing member  42  includes: a bearing main body (not shown) arranged plurally at a substantially equal interval position in the forward-or-rearward direction in a rectangular frame shape integrally formed along an outer periphery of an upper deck of the cylinder head; a bearing section  42   a  having a bearing groove  42   b  of a semi-circular shape at an upper surface of bearing section  42   a  by means of bolts (not shown); and a bearing bracket (not shown) fixed by means of bolts (not shown) on an upper end surface of bearing section  42   a . A semi-circular bearing groove rotatably supporting camshaft  2  in cooperation with bearing groove  42   b  is formed on a lower surface of the bearing bracket. 
     In addition, projection sections  57 ,  58  are integrally installed on bearing member  42  at the forward end side of the engine shown in  FIG. 1  which are a pair of arm shaped positioning sections projected in the radial direction (lateral direction) of camshaft  2  from both sides of bearing section  42   a . These projection sections  57 ,  58  have tip sections  57   a ,  58   a  bent in a substantially letter L is shape projected in the forward direction of cover member  3  side. These tip sections  57   a ,  58   a  are formed in an elongated column shape and a projected length L is extended in a substantial center section in the axial direction of phase modification mechanism  4  from timing sprocket  1  side. 
     Pressing in pin holes  57   b ,  58   b  of projection sections  57 ,  58  into which other end sections  54   b ,  55   b  of respective positioning pins  54 ,  55  are pressed are formed by a predetermined length in the axial direction of projection sections  57 ,  58 . Hence, both of positioning pins  54 ,  55  are disposed at about 180° in the circumferential direction of projection sections  57 ,  58 . 
     An annular washer section  10   c  is arranged on an end surface of a head section  10   a  at an axle section  10   b  side as shown in  FIG. 1  and a male screw section  10   d  screwed to a female screw section formed in an inner axle direction of camshaft  2  from the end section of camshaft  2  is formed on the outer periphery of axle section  10   b.    
     Driven member  9  is integrally formed of the iron-series metal and, as shown in  FIG. 1 , includes: a disk shaped fixture terminal section  9   a  formed at the forward end side; a cylindrical section  9   b  projected in the axial direction from the inner peripheral forward end surface of fixture end section  9   a ; and a cylindrical retainer  41  integrally formed on the outer peripheral section of fixture end section  9   a  to retain a plurality of rollers  48 . 
     Fixture end section  9   a  has a rear end surface contacted and arranged on the forward end surface of flange section  2   a  of camshaft  2  so as to be pressed and contacted from the axial direction by means of an axial force of cam bolt  10 . 
     Cylindrical section  9   b  has a center section, as shown in  FIG. 2 , having an inserting hole  9   d  through which axle section  10   b  of cam bolt  10  is inserted and a needle bearing  38  is disposed on the outer peripheral side of cylindrical section  9   b.    
     Retainer  41  is bent in a substantially letter L shape in cross section from the forward end of the outer periphery of fixture terminal section  9   a , as shown in  FIGS. 1 through 3 , and formed in a bottomed cylindrical shape projected in the same direction as cylindrical section  9   b . A cylindrical tip section  41   a  of this retainer  41  is extended in the direction of bottom section  5   b  of housing  5  via a spatial section  44  which is an annular recess section formed between female screw forming section  6  and extended section  5   d . In addition, a plurality of elongated roller holding holes  41   b  in a substantially elongated shape which are a roller holding section which rollably holds the plurality of rollers  48  at substantially equal interval positions in the circumferential direction of tip end sections  41   a . This roller holding holes  41   b  (roller  48 ) have whole numbers smaller than the whole teeth numbers of inner wheel  19   a  of inner teeth constituent section  19  by one. 
     Then, an inner wheel fixture section  63  which fixes inner wheel  43   b  of large diameter ball bearing  43  is cut out between the outer peripheral section of fixture end section  9   a  and the coupling section at the bottom side of retainer  41 . 
     This inner wheel fixture section  63  is cut out in a step difference shape and is opposed against inner wheel fixture section  63  from a radial direction and includes: an annular outer peripheral surface  63   a  extended in a camshaft axial direction; and a second fixture step difference surface  63   b  integrally formed to be opposite to the opening of outer peripheral surface  63   a  and formed along a radial direction of inner wheel fixture section  63 . 
     Inner wheel  43   b  of large diameter ball bearing  43  is pressed into outer peripheral surface  63   a  from the axial direction of large diameter ball bearing  43  and an inner end surface  43   f  of pressed in inner wheel  43   b  is contacted on second fixture step difference surface  63   b  to make the axial directional positioning. 
     Phase modification mechanism  4  includes: an electrically driven motor  12  arranged on the substantially coaxial forward end side of camshaft  2 ; and a speed reduction mechanism  8  which reduces a rotation speed of electrically driven motor  12  and transmits the reduced revolution speed to camshaft  2 . 
     Electrically driven motor  12  is a DC motor with brush, as shown in  FIGS. 1 and 2 . Electrically driven motor  12  includes: housing  5  which is a yoke integrally rotated with timing sprocket  1 ; a motor output axle  13  rotatably mounted in an inside of housing  5 ; a pair of permanent magnets  14 ,  15  in a semi-arc shape which are stators fixed on the inner peripheral surface fixed on the inner peripheral surface of housing  5 ; and a stator  16  fixed onto sealing plate  11 . 
     Motor output axle  13  functions as an armature formed in the step difference cylindrical shape and is constituted by a large diameter section  13   a  at camshaft  2  side via a step difference section  13   c  formed at the substantial center position of motor output axle  13  in the axial direction of output axle  13  and a small diameter section  13   b  located at a brush holding body  28  side. An iron core rotor  17  is fixed onto the outer periphery of large diameter section  13   a  and an eccentric axle section  39  is pressed into and fixed to an inside of large diameter section  13   a  from the axis direction to make the positioning of eccentric axle section  39  in the axial direction by means of the inner surface of step difference section  13   c . On the other hand, an annular member  20  is pressed into the outer periphery of small diameter section  13   b  and a commutator  21  is pressed into and fixed to the outer peripheral surface of annular member  20  from the axial direction so that the axial positioning is made by means of the outer surface of step difference section  13   c . An outer diameter of annular member  20  is set to approximately the same as the outer diameter of large diameter section  13   a.    
     The axial length of annular member  20  is set to be slightly shorter than small diameter section  13   b.    
     The axial positioning of both of eccentric axle section  39  and commutator  21  by means of inner and outer surfaces of step difference section  13   c  so that an assembly operation becomes facilitated and an accuracy of the positioning can be improved. 
     Iron core rotor  17  is formed by a magnetic material having a plurality of magnetic poles and an outer peripheral surface of iron core rotor  17  is constituted by a bobbin having slots on which coils of an electromagnetic coil  18  are wound. 
     On the other hand, commutator  21  is formed in an annular shape by means of an electrically conductive material and a terminal  18   c  of a coil wire drawn out from electromagnetic coil  18  is electrically connected to each of segments divided in the same number as a pole number of iron core rotor  17 . In other words, a tip of terminal  18   c  of the coil wire is grasped by a folded section formed at the inner peripheral side of commutator  21  to make the electrical connection. 
     Permanent magnets  14 ,  15  are wholly formed in a cylindrical shape and have a plurality of magnetic poles in the circumferential direction thereof. The position in the axial direction of permanent magnets  14 ,  15  is offset toward the further forward direction than the fixture position of iron core rotor  17 . 
     Specifically, the axial centers of permanent magnets  14 ,  15  are, as shown in  FIG. 1 , offset toward the forward direction with respect to the axial center of iron-core rotor  17 , in other words, towards stator  16  side by a predetermined distance. 
     In addition, the offset arrangement of permanent magnets  14 ,  15  causes forward end sections  14   a ,  15   a  of permanent magnets  14 ,  15  to be overlapped with first brushes  25   a ,  25   b  of commutator  21  and stator  16  as will be described later. 
     Stator  16  is, as shown in  FIG. 5 , mainly constituted by: a disc shaped resin plate  22  integrally mounted at the inner peripheral side of sealing plate  11 ; a pair of resin holders  23   a ,  23   b  mounted in the inside of resin plate  22 ; a pair of first brushes  25   a ,  25   b  which are switching brushes (rectifiers) and whose respective tip surfaces are elastically contacted on the outer peripheral surface from the diameter direction by means of a spring force of coil springs  24   a ,  24   b ; inner and outer double annular slip rings  26   a ,  26   b  buried to the forward end surfaces of resin holders  23   a ,  23   b  in a state in which respective end surfaces are exposed; and pigtail harnesses  27   a ,  27   b  which electrically connects respective first brushes  25   a ,  25   b  to respective slip rings  26   a ,  26   b . It should be noted that slip rings  26   a ,  26   b  constitute part of a power supply mechanism and first brushes  25   a ,  25   b , commutator  21 , pigtail harnesses  27   a ,  27   b  constitute power supply switching means. 
     Sealing plate  11  is positioned and fixed to a recess step difference section formed on a forward end section of housing  5 . In addition, an axial inserting hole  11   a  through which one end section of motor output axle  13  is penetrated is formed at the center section of sealing plate  11 . 
     A brush holding body  28  which is a power supply mechanism is fixed to cover main body  3   a  integrally molded by means of a synthetic resin material  28 . 
     This brush holding body  28  is mainly constituted by, as shown in  FIGS. 1 and 2 , a substantially cylindrical brush holding body  28   a  formed in a substantially letter L shape as viewed from a side thereof and inserted into a holding hole  3   d ; a connector section  28   b  formed on an upper end section of brush holding section  28   a ; a pair of brackets  28   c ,  28   c  projected integrally on both sides of brush holding section  28   a ; and a pair of terminal pieces  31 ,  31  a majority of which is buried in an inside of brush holding body  28 . 
     A pair of terminal pieces  31 ,  31  are formed in parallel to each other along a vertical direction and respective terminals  31   a ,  31   a  on one terminal side (lower end side) of pair of terminal pieces  31 ,  31  are exposed to bottom end sides of brush holding section  28   a . Respective terminals  31   b ,  31   b  of the other end side (upper end side) are projected within a female type fitting groove  28   d . In addition, respective other side terminals  31   a ,  31   b  are electrically connected to a battery power supply via a male terminal (not shown). 
     Sleeve shaped slide sections  29   a ,  29   b  are fixed within cylindrical penetrating holes formed on a vertical position of an inside of brush holding section  28   a  which is extended in a substantially horizontal direction (axial direction). Respective tip surfaces of second brushes  30   a ,  30   b  contacted on respective slip rings  26   a ,  26   b  from the axial direction are slidably held in the axial direction. 
     These respective second brushes  30   a ,  30   b  are formed substantially in an elongated body shape. Spring forces of second coil springs  32   a ,  32   b  which are biasing members elastically mounted between one side terminals  31   a ,  31   a  exposed to bottom section sides of respective penetrating holes cause second brushes  30   a ,  30   b  to be biased in respective directions of slip rings  26   a ,  26   b.    
     A pair of pig tail harness having a flexibility are welded and fixed between rear end sections of second brushes  30   a ,  30   b  and one side terminals  31   a ,  31   a  to electrically connect both of second brushes  30   a ,  30   b  and one side terminals  31   a ,  31   b.    
     In addition, an annular seal member  34  is fitted and held within an annular fitting groove formed on an outer periphery at a base section side of brush holding section  28   a  and seal member  34  is elastically contacted on the tip surface of cylindrical wall  3   b  when brush holding section  28   a  is inserted into holding purpose hole  3   d  to seal within brush holding section  28   a.    
     Connector section  28   b  has the upper end section on which other side terminals  31   b ,  31   b  exposed to fitting groove  28   d  into which male terminals (not shown) are inserted electrically connected to a control unit (not shown) via the male type terminals. 
     Bracket sections  28   c ,  28   c  are formed in a substantially triangular shape and on both side sections thereof bolt inserting holes  28   e ,  28   e  are penetrated and formed. Through respective bolt inserting holes  28   e ,  28   e , bolts  59 ,  59  screwed into a pair of female holes (not shown) formed on cover main body  3   a  are fixed to cover main body  3   a  via respective bracket sections  28   c ,  28   c.    
     Motor output axle  13  and eccentric axle section  39  are rotatably supported by means of a small diameter ball bearing  37  disposed on an outer peripheral surface of axle section  10   b  at a head section  10   a  side of cam bolt  10  and a needle bearing  38  disposed on an outer peripheral surface of cylindrical section  9   b  of driven member  9  and arranged at the axial direction side section of small diameter ball bearing  37 . These small diameter ball bearing  37  and needle bearing  38  constitute a bearing mechanism. 
     Needle bearing  38  is constituted by a cylindrical retainer  38   a  pressed in the inner peripheral surface of eccentric axle section  39 ; and a plurality of needle rollers  38   b  which are a plurality of rollable bodies rotatably held on the inner side of retainer  38   a . This needle roller  38   b  rolls on the outer peripheral surface of cylindrical section  9   b  of driven member  9 . 
     Small diameter ball bearing  37  has the inner wheel grasped and fixed between a forward end edge of driven member  9  and a washer  10   c  of cam bolt  10  and has the outer wheel positioned and supported from the axial direction between a step difference section formed on an inner periphery of motor output axle  13  and a snap ring  45  which is a stopper ring. 
     A small diameter oil seal  46  is interposed between the outer peripheral surface of motor output axle  13  (eccentric axle section  39 ) and the inner peripheral surface of extended section  5   d  of housing  5  to block a leakage of lubricant oil from an inside of speed reduction mechanism  8 . This oil seal  46  partitions electrically driven motor  12  and speed reduction mechanism  8 . When the inner peripheral surface of oil seal  46  is elastically contacted on the outer peripheral surface of motor output axle  13 , a frictional resistance is provided for a rotation of output axle  13 . 
     A cap  53  having a cross section in a substantial letter of left inverted U shape is pressed into and fixed to close the spatial section at cam bolt  10  side, as shown in  FIG. 1   
     The above-described control unit detects a present engine driving state on a basis of information signals from various types of sensors such as a crank angle sensor, an airflow meter, a coolant temperature sensor, an accelerator opening angle sensor, and so forth to perform an engine control and supplies electric power to electromagnetic coil  18  to perform a rotational control for motor output axle  13  so as to control a relative rotational phase of camshaft  2  with respect to timing sprocket  1  via a speed reduction mechanism  18  via speed reduction mechanism  8 . 
     As shown in  FIGS. 1 through 3 , speed reduction mechanism  8  is mainly constituted by: eccentric axle section  39  performing an eccentric rotary motion; a middle diameter ball bearing  47  disposed on the outer periphery of eccentric axle section  39 ; roller  48  disposed on the outer periphery of middle diameter ball bearing  47 ; holder  41  allowing the movement of roller  48  in the radial direction while holding roller  48  in a roll direction; and driven member  9  integral with holder  41 . 
     Eccentric axle section  39  is formed cylindrically in a step difference diameter and small diameter section  39   a  at the forward end side of eccentric axle section  39  is pressed into and fixed to the inner peripheral surface of large diameter section  13   a  of motor output axle  13 . An axle center Y of a cam surface formed on the outer peripheral surface of large diameter section  39   b  at the rear end side is slightly eccentric in the diameter direction from axle center X of motor output axle  13 . It should be noted that middle diameter ball bearing  47  and roller  48  constitute a planetary gear section. 
     Middle diameter ball bearing  47  is arranged in a state in which the whole of needle bearing  38  is approximately overlapped in a radial direction position of needle bearing  38  and includes an inner wheel  47   a , an outer wheel  47   b , and a ball  47   c  interposed between inner and outer wheels  47   a ,  47   b . Inner wheel  47   a  is press fitted to the outer peripheral surface of eccentric axle section  39  but outer wheel  47   b  is in a free state without fixture in the axle direction. In other words, this outer wheel  47   b  is in a free state since one end surface of electrically driven motor  12  side does not contact on any position and a minute first gap C′ is formed between the other end surface  47   d  of ball bearing  47  in the axial direction of outer wheel  47   b  and an inner side surface of holder  41  opposing against the other end surface  47   d . An outer peripheral surface of each roller  48  is rollably contacted against an outer peripheral surface of outer wheel  47   b  as shown in  FIG. 2 . An annular second gap C1 is formed on the outer peripheral side of outer wheel  47   b . This second gap C1 causes a whole of middle diameter ball bearing  47  to be movable in the diameter direction involved in an eccentric rotation of eccentric axle section  39 , in other words, eccentrically movable. 
     Each roller  48  is formed of the iron-series metal and fitted into inner teeth  19   a  of inner teeth constituent section  19  while each roller  48  is moved in the radial direction due to the eccentric motion of middle diameter ball bearing  47  and each roller  48  is swingably moved in the radial direction while guided in the peripheral direction of holder  41  by means of both side edges of roller holding hole  41   b  of holder  41 . 
     Lubricating oil is supplied to an inside of speed reduction mechanism  8  by means of lubricating oil supply means. This lubricating oil supply means includes: an oil supply passage formed in the inside of the bearing of the cylinder head and to which the lubricating oil is supplied from a main oil gallery not shown; an oil supply hole  51  formed in a direction of the inner axle of camshaft  2  and communicated with the oil supply passage via a groove; a small diameter oil hole  52  having one end opened to oil supply hole  51  and the other end opened to the vicinity to middle diameter ball bearing  47  and needle bearing  38 ; and large diameter three oil exhaust holes (not shown) penetrated through driven member  9 . 
     Thus, lubricating oil is supplied to the insides of eccentric axle section  39  and motor output axle  13  by above-described lubricating oil supply means and serve to lubricate needle bearing  38  and ball bearing  37  and lubricating oil is also supplied to spatial section  44  and retained therein from which lubricating oil is sufficiently supplied to movable sections of middle diameter ball bearing  47  and each roller  48 . It should be noted that the leakage of lubricating oil retained within spatial section  44  within housing  5  is blocked by means of small diameter oil seal  46 . 
     Hereinafter, an action of the preferred embodiment described above will be explained below. First, when the crankshaft of the engine is rotationally driven, timing sprocket  1  is revolved via the timing chain, its rotational force synchronously revolves electrically driven motor  12 , namely, housing  5  via inner teeth constituent section  19  and female screw forming section  6 . On the other hand, the rotational force of inner teeth constituent section  19  is transmitted from each roller  48  to camshaft  2  via holder  41  and driven member  9 . Thus, the cam of camshaft  2  is operated to open or close the corresponding intake valve. 
     Then, at a time of a predetermined engine driving after the start of engine, the electrical power supply to electromagnetic coil  17  of electrically driven motor  12  is carried out from the control unit via respective terminal pieces  31 ,  31 , respective pigtail harnesses  32   a ,  32   b , second brushes  30   a ,  30   b , respective slip rings  26   a ,  26   b , and so forth. Thus, output axle  13  of motor  12  is rotationally driven and its rotational force is speed reduced via speed reduction mechanism  8  and rotational force speed reduced is transmitted to camshaft. 
     That is to say, when eccentric axle section  39  is eccentrically rotated due to the rotation of output axle  13  of electrically driven motor  12 , each roller  48  rolls and moves riding across one of inner teeth  19   a  and rolls an adjacent another one of teeth  19   a  while each roller  48  is guided in the radial direction through each roller holding hole  41   b  of holder  41  for each rotation of motor output axle  13 . This is sequentially repeated so as to be rollably contacted in the circumferential direction. The rollable contact of each roller  48  reduces the rotation of motor output axle  13  and the rotating force is transmitted to driven member  9 . The speed reduction ratio at this time can arbitrarily be set according to the number of rollers  48 . 
     This causes the relative rotation in the normal or revere direction of camshaft  2  with respect to timing sprocket  1  to convert the relative rotation phase so that the open-or-closure timing of the intake valve(s) is converted and controlled toward the advance angle side or in the retardation angle side. 
     The maximum position limitation (angular position limitation) in the normal and reverse rotation of camshaft  2  with respect to timing sprocket  1  is carried out in such a way that each side surface of stopper convex section  61   b  is contacted on either one of respective opposing surfaces of stopper recess grooves  2   b.    
     Specifically, driven member  9  is revolved in the same direction as the rotation direction of timing sprocket  1  due to (or involved in) the eccentric pivotal movement of eccentric axle section  39  so that one side surface of stopper convex section  61   b  is contacted on opposing surface  1   c  of stopper recess groove  2   b  and the rotation of the same direction is limited. Thus, the relative rotational phase of camshaft  2  to timing sprocket  1  is modified maximally toward the advance angle side. 
     On the other hand, driven member  9  is rotated in the opposite direction to the rotation direction of timing sprocket  1  so that the other side surface of stopper convex section  61   b  is contacted on the opposing surface  2   d  of the other side of stopper recess groove  2   b  for the further rotation in the same direction is limited. Thus, relative rotational phase of camshaft  2  with respect to timing sprocket  1  is maximally modified toward the retardation angle side. 
     Consequently, the valve open-and-closure timings of the intake valves are maximally converted at the advance angle side or the retardation angle side so that the fuel economy of the engine and the improvement in the output can be achieved. 
     In addition, in this embodiment, when the respective components are assembled, in other words, when cover member  3  with respect to phase modification mechanism  4  is assembled, other end sections  54   b ,  55   b  of respective positioning pins  54 ,  55  are previously pressed into and fixed to other end sections  54   b ,  55   b  of press in holes  57   b ,  58   b  of tip sections  57   a ,  58   a  of projection sections  57 ,  58  disposed on bearing member  42  of camshaft  2 . 
     Subsequently, when bearing member  42  is assembled into the cylinder head, one end sections  54   a ,  55   a  of respective positioning pins  54 ,  55  are loosely (movably) inserted into respective inserting holes  49   c ,  49   d  of chain cover  49 . 
     Thereafter, cover member  3  to which large diameter oil seal  50  is prefixed via circular base section  50   a  is tightened to chain cover  49  by means of bolts. However, at this time, each positioning pin hole  3   i ,  3   j  is made coincident with corresponding one end section  54   a ,  55   a  of each of positioning pins  54 ,  55  and the corresponding positioning pin is inserted into corresponding pin hole  3   i ,  3   j . Thus, the radial positioning and circumferential positioning of cover member  3  with respect to chain cover  49  are carried out so that while, in this state, assembling flange  3   b  is contacted on the forward surface of circular wall  49   b  of chain cover  49 , cover member  3  is fixed by means of the bolts. 
     In this way, in this embodiment, while cover member  3  is positioned, cover member  3  is fixed to chain cover  49 , with bearing member  42  of camshaft  2  as a reference utilizing each projection section  57 ,  58 . Hence, while the positional deviation between cover member  3  and phase modification mechanism  4  is suppressed, the assembly work of the respective components can be facilitated. 
     That is to say, camshaft  2  is fixed from the axial direction by means of cam bolt  10  while phase modification mechanism  4  is highly accurately positioned. In addition, cover member  3  is positioned by means of two positioning pins  54 ,  55  fixed to respective projection sections  57 ,  58  integral to bearing member  42  of camshaft  2 . It is possible to make highly accurate positioning of cover member  3  and phase modification mechanism  4  in the radial and circumferential directions. 
     Hence, the radial directional positional accuracy and the circumferential positional accuracy of respective brushes  30   a ,  30   b  disposed on cover member  3  side and respective slip rings  26   a ,  26   b  disposed at phase modification mechanism  4  side are improved and the positional deviation between these members can be suppressed. 
     In addition, the radial directional positioning accuracy of large diameter oil seal  50  with respect to the outer peripheral surface of housing  5  is improved so that a gradient of oil seal  50  and a radial directional positional deviation can be suppressed. 
     Furthermore, while the positioning of cover member  3  is carried out utilizing respective projection sections  57 ,  58 , cover member  3  is fixed to chain cover  49  by means of bolts. Hence, these assembly work can be facilitated. 
     Furthermore, seal ring  56  attached onto cover member  3  has six stopper projection sections  56   b  strongly elastically contacted on the opposing surface of seal holding groove  3   k  of seal ring  56  from the radial direction of seal holding groove  3   k . Hence, the holding force of seal ring  56  to seal holding groove  3   k  is improved. Consequently, an unintentional drop out of seal ring  56  from seal holding groove  3   k  during the assemble work can be eliminated. 
     In addition, since one positional pin hole  3   j  is formed in the elongated hole along the radial direction, a slight positional deviation in the radial direction of cover member  3  with respect to respective positional pins  54 ,  55  can be absorbed. 
     In this embodiment, as described above, one coil winding  18   a  of electromagnetic coil  18  is adjacently disposed at commutator  21  (axial direction) side and other coil winding  18   b  can be housed in recess section  5   e  of housing bottom section  5   b  from the axial direction. Thus, it becomes possible to reduce an axial length of the apparatus as small as possible. Consequently, a mountability of the apparatus on the internal combustion engine can be improved. 
     The present invention is not limited to the structure described in the embodiment but can arbitrarily be modified within a range of a gist of the present invention. 
     In addition, as the eccentric axle section, a wall thickness of inner wheel  47  of middle diameter ball bearing  47  may circumferentially be varied so as to be eccentric to the axial center of ball bearing  47 . In this case, since motor output axle  13  may be extended or may be formed as a co-axial cylindrical section, with abolishment of eccentric axle section  39 . 
     Technical ideas of the invention other than the claims graspable from the embodiment will hereinafter be described below. 
     [Claim a] The valve timing control apparatus for the internal combustion engine as claimed in claim  1 , wherein a seal ring which is constituted by an elastic body arranged along a peripheral direction of the cover member is interposed between the cover member and a fixture surface of the internal combustion engine to which the cover member is fixed and the positioning pins are disposed at an inner peripheral side of the seal ring.
 
[Claim b] The valve timing control apparatus for the internal combustion engine as set forth in claim a, wherein the seal ring is arranged within a seal groove formed on a contact surface provided on an outer peripheral section of the cover member and a stopper section having a larger width than a groove width of the seal groove is partially mounted on the seal ring.
 
[Claim c] The valve timing control apparatus for the internal combustion engine as set forth in claim b, wherein the stopper section is constituted by a pair of projections projected toward the inner peripheral side of the seal ring and toward the outer peripheral side of the seal ring.
 
[Claim d] The valve timing control apparatus for the internal combustion engine as set forth in claim c, wherein the pair of projections are disposed at a plurality of locations of the seal ring in a circumferential direction of the seal ring.
 
[Claim e] The valve timing control apparatus for the internal combustion engine as claimed in claim  1 , wherein the positioning pins are two.
 
[Claim f] The valve timing control apparatus for the internal combustion engine as set forth in claim e, wherein the pair of positioning pins are disposed at opposing positions with an axial center of the camshaft as a center.
 
[Claim g] The valve timing control apparatus for the internal combustion engine as claimed in claim e, wherein each of the positioning pins has one end press fitted into a projection section of the bearing member and one side of the cover member and has the other end inserted into the other side of the cover member.
 
[Claim h] The valve timing control apparatus for the internal combustion engine as set forth in claim  1 , wherein each of the positioning pins has one end press fitted into a pressing in pin hole formed on the projection section and has the other end inserted into an inserting hole formed on the cover member.
 
     This application is based on a prior Japanese Patent Application No. 2012-245000 filed in Japan on Nov. 7, 2012. The entire contents of this Japanese Patent Application No. 2012-245000 are hereby incorporated by reference. Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiment described above. Modifications and variations of the embodiments described above will occur to those skilled in the art in light of the above teachings. The scope of the invention is defined with reference to the following claims.