Patent Publication Number: US-6338322-B1

Title: Valve timing control device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a valve timing control device and, in particular, to the valve timing control device for controlling an angular phase difference between a crankshaft of a combustion engine and a camshaft of the combustion engine. 
     2. Conventional Technology 
     A conventional valve timing control device comprises: a rotary member rotates with a crankshaft of an internal combustion; a rotational transmitting member rotates with a camshaft; a vane provided on the rotary member; and a pressure chamber formed between the rotary member and the rotational transmitting member, and divided into an advancing chamber and a delaying chamber by the vane. The rotational transmitting member has a cylindrical housing member mounted around the peripheral surface of the rotary member, and two circle plate members fixed on ends of the cylindrical housing member and a timing sprocket connected to a crankshaft by a timing chain. Such a conventional variable timing device is disclosed, for example, in Japanese Patent Laid-Open Publication No. H(Heisei) 10-141022. 
     In the conventional valve timing control device, the valve timing is advanced due to relative displacement between the rotary member and the rotational transmitting member the fluid is supplied to the advancing chamber and is discharged from the delaying chamber. On the contrary, the valve timing is delayed due to the counter displacement between the rotary member and the rotational transmitting member when the fluid is discharged from the delaying chamber and is supplied to the delaying chamber. 
     Further, in the conventional valve timing control device disclosed in the publications, there are predetermined gaps between the outside surfaces of the cylindrical housing member and the inside surfaces of each of the plate member. The gaps are filled up with a small amount of the fluid that is leaked from the advancing chamber and/or the delaying chamber so as to make fluid slicks. Therefore, the operation of the conventional valve timing control device quickens. 
     However, even if the rotational phase (the angular phase difference) between the crankshaft and the camshaft is fixed on the internal combustion engine driving, the camshaft receives variational torque so that the rotary member continuously rotates relative to the rotational transmitting member within a small range. At the time, as loads of the gaps to maintain the fluid slicks become large, it is difficult to keep the small amount of the fluid in the gaps. 
     In addition, here exists some risk that the tension of the timing chain, which connects between the crankshaft and the timing sprocket, may make one of the gaps small. As a result, the fluid slick between one of the outside surfaces of the cylindrical housing member and the inside surface of the plate member may disappear such that the internal opposition increases. 
     SUMMARY OF THE INVENTION 
     The invention has been conceived to solve the above-specified problems. According to the invention, there is provided a valve timing control device comprising: a rotary member that rotates with one of a crankshaft of an internal combustion engine or a camshaft thereof; a rotational transmitting member that rotates with the other of the camshaft or the crankshaft, and which has a cylindrical housing portion mounted around the peripheral surface of the rotary member and a circle plate portion fixed on one end of the cylindrical housing portion and slidably contacted with one end of the rotary member; a vane provided on the rotary member; a pressure chamber formed between the rotary member and the rotational transmitting member, and divided into an advancing chamber and a delaying chamber by the vane; and an oil retainer disposed between the circle plate portion of the rotational transmitting member and the rotary member. 
     Other objects and advantages of invention will become apparent during the following discussion of the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and additional features of the present invention will become more apparent from the following detailed description of embodiments thereof when considered with reference to the attached drawings, in which: 
     FIG. 1 is a vertical sectional view of the first embodiment of a valve timing control device in accordance with the present invention; 
     FIG. 2 is a sectional view taken along the line B—B in FIG. 1; 
     FIG. 3 is a sectional view taken along the line C—C in FIG. 1; 
     FIG. 4 is a plan view of a rear plate in FIG. 1; 
     FIG. 5 is a sectional view of the rear plate in FIG. 1; 
     FIG. 6 is a plan view of a rotor of the second embodiment of a valve timing control device in accordance with the present invention; 
     FIG. 7 is a plan view of a rotor of the third embodiment of a valve timing control device in accordance with the present invention; and 
     FIG. 8 is a sectional view taken along the line D—D in FIG.  7 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A valve timing control device in accordance with preferred embodiments of the present invention will be described with reference to the attached drawings. 
     The first embodiment of a valve timing control device according to the present invention, as shown in FIGS. 1 through 5, is constructed so as to comprise a rotary member which includes a rotor  30  that rotates with a camshaft  20 ; a rotational transmitting member mounted around the rotor  30  so as to rotate relative thereto within a predetermined range and including a housing  40 , a front plate  50 , a cap  54 , a rear plate  60  and a timing sprocket  70 ; six vanes  80  assembled with the rotor  30 ; a lock pin (not shown) assembled with the housing  40 . The camshaft  20  is rotatably supported by a cylinder head  10  of an internal combustion engine. The rotor  30  is integrally provided on the leading end portion of the camshaft  20 . The timing sprocket  70  is fixed to the housing  40  by means of three bolts  71 . The timing sprocket  70  is constructed, as is well known in the art, to transmit the rotating power to the clockwise direction of FIG. 2 (the counter-clockwise direction of FIG. 3) from a crankshaft  11  via a timing belt  12 . The timing belt  12  is made of resin or rubber. Here, it is possible to use a timing chain or timing gears instead of the timing belt  12 . 
     The camshaft  20  is equipped with a well-known cam (not shown) for opening and closing an intake valve (not shown) and is provided therein with an advance passage  21  and a delay passage  22 , which are extended in the axial direction of the camshaft  20 . The advance passage  21  is connected to a first connection port  105  of a control valve  100  via a radial passage  25 , an annular passage  13 , a connection passage  14 . On the other hand, the delay passage  22 , which is disposed around a bolt  23 , is connected to a second connection port  106  of the control valve  100  via a radial passage  26 , an annular passage  15  and a connection passage  16 . 
     The control valve  100  includes a solenoid  101 , a spool (not shown) and a spring  107 . In FIG. 1, the solenoid  101  drives the spool leftward against the spring  107  when the solenoid  101  is energized. In the energized state, the control valve  100  connects an inlet port  108  to the first connection port  105  and also connects the second connection port  106  to a drain port  109  (the first position  103 ). On the other hand, in the normal state, the control valve  100  connects the inlet port  108  to the second connection port  106  and also connects the first connection port  105  to the drain port  109  (the second position  102 ), as shown in FIG.  1 . The solenoid  101  of the control valve  100  is energized by an electronic controller (not shown). As a result, an operational fluid (working oil) is supplied to the delay passage  22  when the solenoid  101  is deenergized, and to the advance passage  21  when the same is energized. Because of duty ratio control of the electronic controller, the spool may be linearly controlled so as to be retained at various intermediate position (the third position  104 ). All the ports  105 ,  106 ,  108  and  109  are closed while the spool is retained at the intermediate position. 
     The rotor  30  is integrally fixed in the camshaft  20  by means of the bolt  23  and is provided with six vane grooves  31  for providing the six vanes  80  individually in the radial directions. Both the rotor  30  and the vanes  80  are made of one kind of iron material. Further, the rotor  30  has a fitting hole  32  for fitting the locking pin (not shown) to a predetermined extent in the state shown in FIG. 2, where the camshaft  20 , the rotor  30  and the housing  40  are in synchronized phase (the vanes  80  are in the most delayed position of pressure chambers R). In addition, the rotor  30  has three axial passages  33 , groove passages  35  and radial passages  38 . One end of each of the axial passages  33  is connected to the advancing passage  21  via an annular space  39 , and the other end of the same is connected to the groove passages  35 . The groove passages  35  are for supplying and discharging the operational fluid to and from advancing chambers R 1 , as defined by the individual vanes  80  via the advance passage  21  and the axial passages  33 . The groove passages  38  are for supplying and discharging the operational fluid to and from delaying chambers R 2 , as defined by the individual vanes  80  via the delay passage  22  and an annular space  37 . Further, as shown in FIG. 2, on the outer circumference of the rotor  30 , there is a groove passage  53  which communicates between the fitting hole  32  and one of the delaying chambers R 2   a.  Here, the annular space  37  and the annular space  39  are completely separated by means of a cylindrically portion  30   a  of the rotor  30 . The top of the cylindrically portion  30   a  is fluid tightly fitted to the end portion of the camshaft  20  by the bolt  23 . Each of the vane  80  is urged radially outward by a vane spring  82  disposed between the bottom portion of a vane groove  31  and a groove  81  of the vane  80 . 
     The housing  40  of the rotational transmitting member is so assembled with the outer circumference of the rotor  30  so as to rotate relative thereto within a predetermined range. There is a small gap between the outer circumference of the housing  40  and the inner circumference of the rotor  30  so as to make a fluid slick. To the two sides of the housing  40 , there are joined the front plate  50  and the rear plate  60  with seal members  51  and  61  by means of six bolts  62 . In this structure, the inside surface of the front plate  50  is disposed toward the one end of the vanes  80  and one axial end of the rotor  30  via a small-predetermined gap. On the other hand, the inside surface of the rear plate  60  is disposed toward the other end of the vanes  80  and the other axial end of the rotor  30  via another small-predetermined gap. Thus, the rotational transmitting member can rotate around the rotor  30  via the operational fluid in the small gap and in the small-predetermined gaps. Both of the housing  40  and the rear plate  60  are made of one kind of the iron material, but the front plate  50  is made of one kind of aluminum material. A cap  54  is fluid tightly fixed to the front plate  50  so as to provide a passage  34  which includes the advance passage  21 , the axial passages  33  and groove  35 . Further, six hollow portions  41  and a bore  42  are formed inwardly in the housing  40 , as shown in FIG.  2 . Each of the pressure chambers R are composed of the outer circumference of the rotor  30 , the inside wall of the hollow portions  41  of the housing  40 , the front plate  50  and the rear plate  60 . Each of the pressure chambers R is divided into an advancing chamber R 1  and a delaying chamber R 2  by the vane  80 . The lock pin and a spring (although not shown) for urging the lock pin toward the rotor  30  are contained in the bore  42  that extends in radial direction of the housing  40 . Here, there is an oil seal  17  which is disposed in the cylinder head  10  so as to engage with the outside circumference of a cylinder portion  64  of the rear plate  60 . On the other hand, the inside circumference of the cylinder portion  64  can rotate relative to the outside circumference of the camshaft  20  via an O-ring  65 . In addition, as shown in FIG. 2, the housing  40  has a groove  45  and a hole  46  for draining the operational fluid from the spring portion of the bore  42  into the groove  35  of the passage  34  via a passage  36 . 
     In this embodiment as shown in FIGS. 1, and  3  through  5 , an annular groove  63  is formed on the front surface of the rear plate  60 , where is toward the axial end surface of the rotor  30 . The inward wall of the annular groove  63  is arranged along the inside ends of the vanes  80 . The operational fluid leaks from the chambers R to the annular groove  63  via the small-predetermined gap between the front surface of the rear plate  60  and the axial end surface of the rotor  30 . The operational fluid in the annular groove  63  is maintained so as to keep fluid slick there between. Accordingly, the rotational area between the front surface of the rear plate  60  and the axial end surface of the rotor  30  slides smoothly. 
     In this embodiment, in order to limit the relative rotation between the rotor  30  and the rotational transmitting member (the housing  40 , the front plate  50  and the rear plate  60 ) within a predetermined range, one of the vanes  80  (a vane  80   a  which is described at the lower left in FIG. 2) touches with stoppers  41   a  and  41   b.  As shown in FIGS. 2 and 3, when the vane  80   a  touches with the stopper  41   a,  each of the groove. passage  35  communicates with each of the advancing chamber R 1 , respectively. On the other hand, when the vane  80   a  touches with the stopper  41   b,  each of the radial passage  38  communicates with each of the delaying chamber R 2 , respectively. 
     In the above embodiment, when the internal combustion engine stalls, an oil pump  110  is no longer driven by the internal combustion engine and the solenoid  101  of the control valve  100  is not energized so that the pressure chambers R do not receive the operational fluid anymore. In this condition, neither the pressure in the advancing chamber R 1  nor the pressure in the delaying chambers R 2  is applied to the vanes  80 , but only the rotational counter force is applied to the vanes  80  toward the most delayed position until the crankshaft  11  of the internal combustion engine is completely stopped. Further, the lock pin (not shown) locks between the rotor  30  and the housing  40  at the most delayed portion between the rotor  30  and the housing  40 . 
     Then, when a starter switch turns on for cranking the internal combustion engine, the solenoid  101  of the control valve  100  is not energized so that the operational fluid supplies to the connection passage  16  via the control valve  100 . Then each of the delaying chambers R 2  is supplied the operational fluid. At the same time, the connection passage  14  connects to an oil pan  111  via the control valve  100  so that the operational fluid discharges from the advancing chambers R 1  to the oil pan  111  via the passage  34  and the advancing passage  21 . In addition, it takes a predetermined time to fill the fitting hole  32  with the operational fluid. Since this operation prevents the rotor  30  with vanes  80  from rotating relative to the housing  40 , the vane  80   a  does not contact with either stopper  41   a  or  41   b  thereby preventing noise in the cranking period. 
     After the predetermined time, the fitting hole  32  is filled with the operational fluid so as to slide the lock pin (not shown) toward the bore  42 . As the lock pin releases the connection between the rotor  30  and the housing  40 , the rotor  30  with vanes  80  can rotate relative to the rotational transmitting member (the housing  40  and so on). 
     At this condition, if the duty ratio of current to supply the solenoid  101  of the control valve  100  increases, the operational fluid supplies to the advance passage  21  and discharges from the delay passage  22 . The pressure of the operational fluid in the advancing chambers R 1  increases so as to urge the vanes  80  toward the advanced direction until it reaches the most advanced position, where the vane  80   a  contacts with the stopper  41   b.  After that, if the duty ratio of current to supply the solenoid  101  of the control valve  100  decreases, the operational fluid in the delaying chambers R 2  increases and the operational fluid in the advancing chambers R 1  decreases so as to urge the vanes  80  toward the delayed direction. As a result, the relative rotational phase between the crankshaft  11  and the camshaft  20  is controlled according to the conditions of the internal combustion engine. 
     Further, the duty ratio of the solenoid  101  of the control valve is controlled so as to supply both of the advancing chamber R 1  and the delaying chamber R 2  with the operational fluid. As a result, the rotational phase between the rotor  30  and the rotational transmitting member (the housing  40  and so on) can vary between the most delayed position and the most advanced position. At that time, the rotor  30  receives torque toward the delayed direction, since the camshaft  20  receives variational torque from the cams (not shown). Thus, the operational fluid pressure of the advancing chamber R 1  is greater than that of the delaying chamber R 2  by the duty ratio of the solenoid  101  of the control valve  100 . 
     In the above condition where the rotational phase between the crankshaft  11  and the camshaft  20  is fixed, the variational torque for urging the camshaft  20  makes the rotor  30  rotate relative to the rotational transmitting member within the small range. Accordingly, the axial end surface of the rotor  30  continuously rotates relative to the front surface of the rear plate  60  within the small range. However, in this embodiment, the annular groove  63  of the front surface of the rear plate  60  can keep the operational fluid so as to make the fluid slick between the rotor  30  and the rear plate  60 . 
     FIG. 6 illustrates another modified version of the first embodiment, which specifically is a modified arrangement of a rotor  130 . In this embodiment, the same parts in the first embodiment are used with the same numerals of the first embodiment. In this modified construction, there is an arc groove  130 A of the axial end surface of the rotor  130 , where the axial end surface is toward the front surface of the rear plate  60 . Here, since the groove  145  for draining the operational fluid from the spring portion of the bore  42  is disposed on the axial end surface of the rotor  130 , the arc groove  130 A is not an annular form so as to separate from the groove  145 . In this embodiment, the arc groove  130 A keeps the operational fluid so as to make the fluid slick between the rotor  130  and the rear plate  60 . 
     FIGS. 7 and 8 illustrate another modified version of the first embodiment, which specifically is a modified arrangement of a rotor  230 . In this embodiment, the same parts in the first embodiment are used with the same numerals of the first embodiment. In this modified construction, there are annular grooves  230 A. In this embodiment, each of the annular grooves  230 A maintains the operational fluid so as to make the fluid slick between the rotor  230  and the rear plate  60 . 
     Here, the above grooves  63 ,  130 A and  230 A for keeping the operational oil are also provided on the rotational portion between the other axial end surface of the rotor  30  ( 130 ,  230 ) and the rear surface of the front plate  50 . 
     Further, in the above embodiment, the camshaft  20  drives the air intake valves of the internal combustion engine. However, this invention may adapt to the other camshafts that drive the exhaust valves of an internal combustion engine.