Valve timing control device

Abstract: A valve timing control device includes a rotor (17) fixed on a cam shaft (2), a housing member (19) rotatably mounted on the cam shaft (2) so as to surround the rotor (17), a chamber (20) defined between the housing member (19) and the rotor (17) and having a pair of circumferentially opposed walls (19a1, 19a2), a vane (18) mounted on the rotor (17) and extending outwardly therefrom in the radial direction into the chamber (20) so as to divide the chamber (20) into a first pressure chamber (30) and a second pressure chamber (31), and a fluid supplying device (38) for supplying fluid under pressure selectively to the first pressure chamber (30) or to the second pressure chamber (31) wherein dirt collection grooves (36,37) are formed along the radially outer ends of each of the opposed walls (19a1, 19a2) of the chamber (20). Any dirt in the hydraulic fluid is thrown outwardly to collect in the grooves (36,37) so that the device continues to operate reliably even when there is foreign matter in the hydraulic fluid.

Description: BACKGROUND OF THE INVENTION 1. Field of the invention: The present invention relates to a valve timing control device and is particular to a valve timing control device for controlling an angular phase difference between a crank shaft of a combustion engine and a cam shaft of the combustion engine. 2. Description of the prior art: In general, a valve timing of a combustion engine is determined by valve mechanisms driven by a cam shaft according to a characteristic of the combustion engine or a use of the combustion engine. Since a condition of the combustion is changed in response to the rotational speed of the combustion engine, however, it is difficult to obtain an optimum valve timing through the whole rotational range. Therefore, a valve timing control device which is able to change a valve timing in response to the condition of the combustion engine is proposed as an auxiliary mechanism of the valve mechanism in recent years. A conventional device of this kind is disclosed, for example, in U.S.Patent No. 4,858,572. This device includes a rotor which is fixed on the cam shaft, a drive member which is driven by the rotational torque from a crank shaft and which rotatably mounted on the cam shaft so as to surround the rotor, a plurality of chambers which are defined between the drive member and the rotor and each of which has a pair of circumferentially opposed walls and a plurality of vanes which are mounted to the rotor and which is extended outwardly therefrom in the radial direction into the chambers so as to divide each of the chambers into a first pressure chamber and a second pressure chamber. In this device, a fluid under pressure is supplied to a selected one of the first pressure chamber and the second pressure chamber in response to the running condition of the combustion engine and an angular phase difference between the crank shaft and the cam shaft is controlled so as to advance or retard the valve timing relative to the crank shaft. The valve timing control device is in the position of the maximum advanced condition, when each of the vanes contacts with one of the opposed walls of each of the chambers. On the other hand, the valve timing control device is in the position of the maximum retarded condition, when each of vanes contacts with the other of the opposed walls of each of the chambers. In the above prior device, if the fluid which contains foreign matter is supplied to the chamber and the foreign matter gets in between the vane and the opposed wall in the above mentioned maximum advanced or retarded condition, it is not able to exactly obtain the maximum advanced or retarded condition and therefore it is impossible to exactly control the valve timing. Further, if the foreign matter gets in between the top end portion of the vane and an outer circumferential wall of the chamber, the fluid-tightness between the first pressure chamber and the second pressure chamber deteriorates. This causes the decrease of the response of the valve timing control device. SUMMARY OF INVENTION It is, therefore, an object of the present invention to provide an improved valve timing control device which overcomes the above drawbacks. It is another object of the present invention to provide an improved valve timing control device which can exclude bad effects due to the foreign matter in the fluid. The invention provides a valve timing control device comprising: a rotor adapted to be fixed on a cam shaft of an engine; a housing member adapted to be rotatably mounted on the cam shaft so as to surround the rotor; at least one chamber defined between the housing member and the rotor and having a pair of circumferentially opposed walls; for each chamber, a vane which is mounted on the rotor and extends radially outwardly therefrom into the chamber so as to divide the chamber into a first pressure chamber and a second pressure chamber; and a fluid supply control means for supplying fluid under pressure selectively to the or each first pressure chamber or to the or each second pressure chamber; CHARACTERIZED IN THAT a dirt-collecting groove is formed on the radially outer end of each of the opposed walls of the or each chamber, facing the associated vane. BRIEF DESCRIPTION OF THE DRAWINGS Additional objects and advantages of the present invention will become more apparent from the following detailed description of a preferred embodiment thereof when considered with reference to the attached drawings, in which: Fig. 1 shows a sectional view of a first embodiment of a valve timing control device in accordance with the present invention; Fig. 2 shows a cross-sectional view taken on line II-II of Fig. 1; Fig. 3 shows an expanded sectional view of the essential parts of the present invention; Fig. 4 shows a sectional view of a second embodiment of a valve timing control device in accordance with the present invention; Fig. 5 shows a cross-sectional view taken on line V-V of Fig. 4; Fig. 6 shows a sectional view of a third embodiment of a valve timing control device in accordance with the present invention; and Fig. 7 shows a cross-sectional view taken on line VII-VII of Fig. 6. 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 attached drawings. Fig. 1 and Fig. 2 show a first embodiment of the present invention. In this first embodiment, a valve timing control device according to the present invention is applied to an engine E of DOHC (Double Over Head Cam Shaft) type. Referring to Fig. 1, an exhaust cam shaft 2 (a first cam shaft) and an intake cam shaft 3 (a second cam shaft) are rotatably mounted on a cylinder head 1 of an engine and are connected each other by a rotational torque transmitting means 6. The rotational torque transmitting means 6 is comprised of a gear 4 which is rotatably mounted on the exhaust cam shaft 2 and a gear 5 which is fixedly mounted on the intake cam shaft 3. An end of the exhaust cam shaft 2 is projected out of the cylinder head 1 and a timing pulley 7 is fixed to this projecting end of the exhaust cam shaft 2 by a bolt 8. A stopper pin 9 is fixed to the projecting end of the exhaust cam shaft 2 and is fitted into a notch formed on the timing pulley 7 so that the relative rotation between the timing pulley 7 and the exhaust cam shaft 2 is prevented. Rotational torque is transmitted to the timing pulley 7 via a belt 49 from a crank shaft 48 which is rotated by the engine. An cylindrical portion 10 of the exhaust cam shaft 2 which is extended into the cylinder head 1 is provided with a male screw portion 11 on which a male screw is formed and a passage portion on which two circular grooves 12, 13 are formed in order from a front side (left side in Fig. 1). The circular grooves 12, 13 are formed so as to maintain a predetermined distance between each other. At the adjacent portion of the passage portion (at the right side of the passage portion in Fig. 1), a journal portion 14 having a larger diameter than the that of the passage portion is formed and a plurality of cam portions 15 are continuously formed at the right side of the journal portion 14. On the journal portion 14, the gear 4 having three female screw holes which are penetrated in the axial direction which are separated in the cicumferential direction at regular intervals is rotatably mounted thereon. On the passage portion of the exhaust cam shaft 2, a valve timing control mechanism 16 is mounted thereon. As shown in Fig. 2, the valve timing control mechanism 16 includes a rotor 17, six vanes 18, a housing member 19, a circular front plate 21 and a circular rear plate 22. The rotor 17 has a cylindrical shape and is fixedly mounted on the passage portion of the exhaust cam shaft 2 by a pin 32. The pin 32 is pressed in the passage portion of the exhaust cam shaft 2 in the radial direction and is fitted into a notch portion 33 formed on the inner circumferential portion of the rotor 17 so that the relative rotation between the rotor 17 and the exhaust cam shaft 2 is prevented. The housing member 19 has a cylindrical shape having an inner bore 19b and is rotatably mounted on the outer circumferential surface of the rotor 17 so as to surround the rotor 17. The housing member 19 has the same axial length as the rotor 17 and is provided with six grooves 19a which are outwardly extended from the inner bore 19b in the radial direction and which are separated in the circumferential direction at regular intervals. The housing member 19 is also provided with three holes which are penetrated in the axial direction and which are separated in the circumferential direction at regular intervals. The rear plate 22 is rotatably mounted on the journal portion 14 so as to locate between the gear 4 and one side face of the housing 19 and the rotor 17 and is provided with three holes which are penetrated in the axial direction and which are separated in the circumferential direction at regular intervals. The front plate 21 is located so as to be opposite to the other side face of the housing member 19 and the rotor 17 and is provided with three holes which are penetrated in the axial direction and which are separated in the circumferential direction at regular intervals. Three bolts 23 are fitted into the holes of the front plate 21, the housing member 19 and the rear plate 22 and are screwed into the female screw holes of the gear 4. Seal members 24 are interposed between the front plate 21 and the other side face of the housing 19 and between the rear plate 22 and one side face of the housing 19, respectively. Thereby, the front plate 21 is fluid-tightly pressed to the other side face of the housing 19 and the rear plate 23 is fluid-tightly pressed to one side face of the housing 19. Now, one side face of the rotor 17 is contacted with a stepped portion 14a of the journal portion 14 and under this condition a nut 25 is screwed onto the male screw portion 11 of the exhaust cam shaft 2 so as to press the rotor 17 toward the journal portion 14. Thereby, rotor 17 is rotated with the exhaust cam shaft 2 in a body. Thereby, six chambers 20 which are separated in the cicumferential direction at regular intervals and each of which has a pair of circumferentially opposed walls 19al, 19a2 are defined among the rotor 17, the housing menber 19, the front plate 21 and the rear plate 22. On the outer circumferential portion of the rotor 17, six grooves 17a which are extended inwardly therefrom in the radial direction and which are separated in the cicumferential direction at regular intervals are formed thereon. Six vanes 18 which are extended outwardly in the radial direction into the chambers 20 are mounted in the grooves 17a, respectively. Thereby, each of chambers 20 is divided into a first pressure chamber 30 and a second pressure chamber 31, both of which are fluid-tightly separated from each other. In this embodiment, grooves 36, 37 which are extended in the axial direction are formed on the radially outer end portions of the opposed walls 19a1, 19a2, respectively. These grooves 36, 37 correspond to a concave portion of the present invention, respectively. The rotor 17 is provided with six first passages 28 and six second passages 29. One end of each of the first passages 28 is communicated with the circular groove 13 and the other end of each of the first passages 28 is communicated with each of the first pressure chambers 30. On the other hand, one end of each of the second passages 29 is communicated with the circular groove 12 and the other end of each of the second passages 29 is communicated with each of the second pressure chambers 31. The circular groove 13 is communicated with a passage 27 which is formed in the exhaust cam shaft 2 at its axial center and which is extended in the axial direction via a passage 46. The circular groove 12 is communicated with a pair of passages 26 which are formed in the exhaust cam shaft 2 so as to locate on the coaxial circle about the axial center of the shaft 2 and which are extended in parallel in the axial direction via passages 45. Now, in this embodiment, the passage 27 is formed at the same time the lubrication passage for the journal portions (not shown) which are located at the right side of the exhaust cam shaft 2 in Fig. 1 is formed. The passage 27 is separated from the lubrication passage by a ball 35 which is pressed into the lubrication passage and is separated from outside by a ball 34 which is pressed into the passage 27. On the other hand, the passages 26 are symmetrical about the passage 27 and have the same flow resistance as that of the passage 27. Therefore, the passages 26, 27 which have a predetermined flow resistance can be obtained by the machining without increasing the diameter of the cam shaft 2. A portion which is located between the cylindrical portion 10 and the projecting end portion of the exhaust cam shaft 2 is rotatably supported on the cylinder head 1 and a cover (not shown) and is provided with a circular groove 43. The circular groove 43 is communicated with the passages 26. The supporting surface of the cylinder head 1 and the cover (not shown) for supporting the exhaust cam shaft 2 is provided with a circular groove 44. The circular groove 44 is communicated with the passage 27 via a passage 47. A fluid supplying device 38 is comprised of a changeover valve 39, a fluidpump 40 and a controller 41. In this embodiment, the changeover valve 39 is an electromagnetic valve which is 4 ports - 3 positions type. The fluid pump 40 is driven by the engine and discharges the fluid (=oil) for lubricating the engine. The pump 40 may be a pump for lubricating the engine. The circular groove 44 is communicated to an A port of the changeover valve 39 and the circular groove 43 is communicated to a B port of the changeover valve 39. A P port of the changeover valve 39 is communicated to a discharge portion the fluid pump 40 and a R port of the changeover valve 39 is communicated to a reservoir 42. The position of the changeover valve 39 is controlled by the controller 41 so that a first condition in which the discharged fluid from the pump 40 is supplied to the circular groove 44 and in which the circular groove 43 is communicated to the reservoir 42, a second condition in which the communication between the circular grooves 43, 44 and the pump 40 and the reservoir 42 are interrupted, respectively and in which the discharged fluid from the pump 40 is supplied to the reservoir 42 and a third condition in which the discharged fluid from the pump 40 is supplied to the circular groove 43 and in which the circular groove 44 is communicated to the reservoir 42 are selectively obtained. The controller 41 controls the above conditions of the changeover valve 39 based on parameter signals which are an engine speed, an amount of opening of a throttle valve (not shown) and so on. The operation of the valve timing control device having the above structure will now be described. With the starting of the engine, the exhaust cam shaft 2 is rotated clockwise by the timing pulley 7 in Fig. 2 . Thereby, exhaust valves (not shown) are opened and closed. Simultaneously, the rotor 17 is rotated and then gear 4 is rotated via the vanes 18, the housing member 19 and the bolts 23. The rotation of the gear 4 is transmitted to the gear 5 and then the intake cam shaft 3 is rotated so that intake valves (not shown) are opened and closed. The gear 4 is rotatably mounted on the journal portion 14 of the exhaust cam shaft 2. Therefore, when the pressurized fluid is supplied from the pump 40 to the second pressure chambers 31 by the changeover valve 39 changed to the third condition via the circular groove 43, the passages 26 and 45, the circular groove 12 and the second passages 29, the housing member 19, the front plate 21 and the second plate 22 are rotated clockwise with the gear 4 relative to the exhaust cam shaft 2 in Fig. 2. Thereby, the valve timing control mechanism 16 is in the position of the maximum advanced condition in which the vanes 18 are contacted with the walls 19al of the chambers 20 and in which the angular phase of the intake cam shaft 3 is advanced relative to that of the exhaust cam shaft 2 (= the crank shaft 48) by maximum value  in Fig. 2. From this condition, when the pressurized fluid is supplied from the pump 40 to the first pressure chambers 30 by the changeover valve 39 changed to the first condition via the circular groove 44, the passages 47, 27 and 46, the circular groove 13 and the first passages 28, the housing member 19, the front plate 21 and the second plate 22 are rotated counterclockwise with the gear 4 relative to the exhaust cam shaft 2 in Fig. 2. Thereby, the valve timing control mechanism 16 is in the position of the maximum retarded condition in which the vanes 18 is contacted with the walls 19a2 of the chambers 20 and in which the angular phase of the intake cam shaft 3 is retarded relative to that of the exhaust cam shaft 2 (= the crank shaft 48) by maximum value  from the above mentioned maximum advanced condition. Now, depending on the manner in which the control of the changeover valve 39 is executed, the vanes 18 can be stopped in any position (intermediate advanced position) between the maximum advanced position and the maximum retarded position. This requires that balance be achieved between the fluid pressure of the first pressure chambers 30 and the fluid pressure of the second pressure chambers 31 when the vanes 18 have achieved an arbitrary position. The amount of the advance can therefore be set to any value between a zero level and a maximum level. As mentioned above, the opening and closing timing of the intake valves (not shown) driven by the intake cam shaft 3 is adjusted and the angular phase difference between the crank shaft 48 and the intake cam shaft 3 is adjusted. Further, in this embodiment, since the grooves 36 and 37 which are extended in the axial direction are formed on the radially outer end portions of the opposed walls 19al and 19a2, respectively, even if the fluid which contains foreign matters is supplied to the chambers 20, the foreign matters are moved outwardly in the radial direction by the centrifugal force due to the rotation of the rotor 17 and are collected into the grooves 36 and 37 by the vanes 18. Accordingly, since it is prevented that the foreign matters are located between the vanes 18 and the walls 19a1, 19a2, the amount of the maximum advance or the maximum retard is always maintained at the predetermined amount. Further, if the foreign matters are located between the vanes 18 and the walls 19a1, 19a2 and are collected, the foreign matters reach between the top end portion of the vanes 18 and the outer circumferential walls of the chambers 20 and the fluid-tightness between each of the first pressure chambers 30 and each of the second pressure chambers 31 deteriorates. In this embodiment, however, since the foreign matters are always collected into the grooves 36, 37, it is able to exclude the bad effects due to the foreign matters and therefore it is able to maintain the good response of the valve timing control device. Further, in case of that each of the vanes 18 has a rounded or sharp-pointed edge portion 18a at its top portion as shown in Fig. 3, since the interference between each of the edge portions 18a and each of the radially outer end portions of the opposed walls 19a1 and19a2 are prevented by each of the grooves36, 37, the amount of the maximum advance or the maximum retard is always maintained at the predetermined amount. Now, the volume of each of the grooves 36, 37 is determined larger than the amount of foreign matter which is allowed to be contained in the fluid by a standard of the engine. Fig. 4 and Fig. 5 show a second embodiment of the present invention. In Fig. 4 and Fig. 5, the same parts as compared with Fig. 1 and Fig. 2 are identified by the same reference numerals. Referring to Fig. 4 and Fig. 5, six passages 113 which are extended outwardly from the passage 27 in the radial direction are formed on the exhaust cam shaft 2 so that each of the passages 113 is always communicated with each of the first passages 128. According to this embodiment, since the length of the passage between the passage 27 and each of the first pressure chambers 30 becomes the same, the pressurized fluid is supplied from the pump 40 to each of the first pressure chambers 30 at the same time by the changeover valve 39 changed to the first condition via the circular groove 44, the passages 47, 27 and 113 and the first passages 128. Thereby, the above mentioned relative rotation between the rotor 17 and the housing 19 is rapidly performed and the response of the valve timing control device is improved. Further, since this relative rotation is smoothly performed without being pulsatingly rotated, the adjusting operation is smoothly performed. Now, in this embodiment, the passage 113 are communicated to the first pressure chambers 30 (retard side). However, pressurized fluid is able to communicate between the passages 27 and the second pressure chambers 31 (advance side) via the passages 113. In this case, the first pressure chambers 30 are communicated to the passages 26 via the circular groove and the first passages. Further, pressurized fluid is able to communicate between the first pressure chambers 30 and the passage 27 and between the second pressure chambers 31 and the passages 26 via the radially outwardly extending passages 128 and 129, respectively. In case that the passages 26 and 27 are not overlapped with each other in the axial direction, the pressurized fluid is supplied from the pump to each of the first pressure chambers at the same time and is supplied from the pump to each of the second pressure chambers at the same time. In case that the passages 26 and 27 are overlapped with each other in the axial direction, the passages 26 and 27 are formed so as not to be co-axial with respect to the axial center of the cam shaft and the number of the pressure chambers to which the pressurized fluid is supplied at the same time is limited. According to this embodiment, since the grooves 36 and 37 which are extended in the axial direction are formed on the radially outer end portions of the opposed walls 19a1 and 19a2, respectively, it is able to obtain the same effects as the above first embodiment. Now, in this embodiment, the contacting portions between the front plate 21 and the housing member 19 and between the rear plate 22 and the housing member 19 are sealed by a metal touch, respectively. However, it is able to interpose a seal member which is bent so that the bolts 23 is located outside of the seal portion, respectively as shown in Fig. 2. Fig. 6 and Fig. 7 show a third embodiment of the present invention. In Fig. 6 and Fig. 7, the same parts as compared with Fig. 1 and Fig. 2 are identified by the same reference numerals. Referring to Fig. 6 and Fig. 7, a cam shaft 50 which is provided with a plurality of cam portions 51 driving valves (not shown) is rotatably supported on a cylinder head 54 of an engine at its plural journal portions 52. Now, the cylinder head 54 is provided with a plurality of semicircular supporting portions 54a and a plurality of covers (not shown) each of which has the corresponding semicircular supporting portion opposing to each of the supporting portions 54a are fixed to the cylinder head 54 so that the journal portions 52 are rotatably supported between the supporting portions 54a of the cylinder head 54 and the supporting portions of the cover. An end 53 of the cam shaft 50 is projected out of the cylinder head 54 and a timing gear 55 is rotatably mounted on this projecting end 53 of the cam shaft 50. Rotational torque is transmitted to the timing gear 55 via a chain 57 from a crank shaft 58 which is rotated by the engine. The timing gear 55 is provided with three female screw holes which are penetrated in the axial direction and which are separated in the cicumferential direction at regular intervals. The timing gear 55 is provided with a circular projecting portion 55a projected in the axial direction at its one end surface and a flat surface at its the other end surface. The circular projecting portion 55a can be contacted with a flange portion 53a which is formed on the outer circumferential portion of the projecting end 53 of the cam shaft 50. A cylindrical rotor 56 having a stepped inner bore 56a is fixedly mounted on the projecting end 53 of the cam shaft 50 by a pin (not shown) so that the relative rotation between the rotor 56 and the cam shaft 50 is prevented. The rotor 56 is fitted onto the projecting end 53 of the cam shaft 50 at its large diameter portion of the stepped inner bore 56a and a stepped portion between the large diameter portion and a small diameter portion of the stepped inner bore is contacted with a top surface of the projecting end 53 of the cam shaft 50. One side surface of the rotor 56 is contacted with the flat surface of the timing gear 55. A cylindrical housing member 59 having a inner bore 59a is rotatably mounted on the outer circumferential surface of the rotor 56 so as to surround the rotor 56. The housing member 59 has the same axial length as the rotor 56 and is provided with five grooves 59b which are outwardly extended from the inner bore 59a in the radial direction and which are separated in the circumferential direction. The housing member 59 is further provided with three penetrating holes in the axial direction which are separated from each other at regular intervals. One side surface of the housing 59 is contacted with the flat surface of the timing gear 55. A circular front plate 60 which is provided with three penetrating holes in the axial direction which are separated from each other at regular intervals is disposed adjacent to the other side surfaces of the rotor 56 and the housing member 59. Each of the holes of the front plate 60, each of the holes of the housing member 59 and each of the female screw holes of the timing gear 55 are coaxially arranged each other and a bolt 61 is fitted into each of the coaxially arranged holes. Each of the bolts 61 is screwed into each of the female screw holes of the timing gear 55. Thereby, the rotor 56, the housing member 59, the timing gear 55 and the front plate 60 are united. The flat surface of the timing gear 55 is fluid-tightly pressed onto one side surface of the rotor 56 and the housing member 59 and one side surface of the front plate 60 is fluid-tightly pressed onto the other side surface of the rotor 56 and the housing member 59. A central screw hole 53b which is opened outside and whose diameter is the almost same as that of the front plate 60 are formed at a axial center of the projecting end 53 of the cam shaft 50. A central bolt 62 is screwed into the central screw hole 53b and thereby the rotor 56 is fixed to the projecting end 53 of the cam shaft 50. Thereby, five chambers 63 which are separated in the cicumferential direction and each of which has a pair of circumferentially opposed walls 59b1, 59b2 are defined among the rotor 56, the housing member 59, the front plate 60 and the timing gear 55. On the outer circumferential portion of the rotor 56, five grooves 59c which are extended inwardly therefrom in the radial direction and which are separated in the cicumferential direction are formed thereon. Five vanes 64 which are extended outwardly in the radial direction into the chambers 63 are mounted in the grooves 59c, respectively. Thereby, each of chambers 63 is divided into a first pressure chamber 65 and a second pressure chamber 66, both of which are fluid-tightly separated from each other. In this embodiment, grooves 67, 68 which are extended in the axial direction are formed on the radially outer end portions of the opposed walls 59b1, 59b2, respectively. The rotor 56 is provided with five first passages 69 and five second passages 70. One end of each of the first passages 69 is communicated with a circular groove 72 which is formed on the large diameter portion of the stepped bore 56a of the rotor 56. The other end of each of the first passages 69 is communicated with each of the first pressure chambers 65. On the other hand, one end of each of the second passages 70 is communicated with a circular groove 71 which is formed on the outer circumferential portion of the projecting end 53 of the cam shaft 50. The other end of each of the second passages 70 is communicated with each of the second pressure chambers 66. The circular groove 72 is communicated with a pair of grooves 73 which are symmetrically formed with regard to the axial center of the cam shaft 50 on the top surface of the projecting end 53 of the cam shaft 50. The grooves 73 are communicated with a pair of passages 74 which are formed on a coaxial circle about the axial center of the cam shaft 50 and which are extended in the axial direction. The circular groove 71 is communicated with a pair of passages 75 via a pair of passages 77 which are symmetrically formed with regard to the axial center of the cam shaft 50 in the projecting end 53 and which are extended in the radial direction. The passages 75 are formed on the coaxial circle about the axial center of the cam shaft 50 and are separated from the passages 74 in the circumferential direction at a predetermined angle. The passages 75 are extended in the axial direction and a ball 76 is pressed into one end of each passages 75 which is opened toward the stepped portion of the rotor 56. A pair of circular grooves 78 and 79 are formed on the journal portion 52 of the cam shaft 50. The circular groove 78 is communicated with the passages 74 via a pair of passages 80 which are extended in the radial direction. The circular groove 79 is communicated with the passages 75 via a pair of passages 81 which are extended in the radial direction. A fluid supplying device 90 is comprised of a changeover valve 91, a fluid pump 92 and a controller 93. In this embodiment, the changeover valve 91 is an electromagnetic valve which is 4 ports - 3 positions type. The fluid pump 92 is driven by the engine and discharges the fluid (=oil) for lubricating the engine. The pump 92 may be a pump for lubricating the engine. The circular groove 78 is communicated to an A port of the changeover valve 91 and the circular groove 79 is communicated to a B port of the changeover valve 91. A P port of the changeover valve 91 is communicated to a discharge portion the fluid pump 92 and a R port of the changeover valve 91 is communicated to a reservoir 94. The position of the changeover valve 91 is controlled by the controller 93 so that a first condition in which the discharged fluid from the pump 92 is supplied to the circular groove 78 and in which the circular groove 79 is communicated to the reservoir 94, a second condition in which the communication between the circular grooves 78, 79 and the pump 92 and the reservoir 94 are interrupted, respectively and in which the discharged fluid from the pump 92 is supplied to the reservoir 94 and a third condition in which the discharged fluid from the pump 92 is supplied to the circular groove 79 and in which the circular groove 78 is communicated to the reservoir 94 are selectively obtained. The controller 93 controls the above conditions of the changeover valve 91 based on parameter signals which are an engine speed, an amount of opening of a throttle valve (not shown) and so on. The operation of the valve timing control device having the above structure will now be described. With the starting of the engine, the cam shaft 50 is rotated clockwise by the timing gear in Fig. 7 . Thereby, the housing member 59 is rotated and the rotational torque of the housing member 59 is transmitted to the rotor 56 via the vanes 64. Then, the cam shaft 50 is rotated clockwise in Fig. 7 and the valves (not shown) are opened and closed. The timing gear 55 is rotatably mounted on the projecting end 53 of the cam shaft 50. Therefore, when the pressurized fluid is supplied from the pump 92 to the first pressure chambers 65 by the changeover valve 91 changed to the third condition via the circular groove 79, the passages 81 and 74, the grooves 73, the circular groove 72 and the first passages 29, the vanes 64 and the rotor 56 are rotated clockwise relative to the housing member 59 and the timing gear 55 in Fig. 7 until the vanes 64 are contacted with the walls 59b2. Thereby, the valve timing control device is in the position of the maximum advanced condition in which the angular phase of the cam shaft 50 is advanced relative to that of the crank shaft 58 by a predetermined maximum value. From this condition, when the pressurized fluid is supplied from the pump 92 to the second pressure chambers 66 by the changeover valve 91 changed to the first condition via the circular groove 78, the passages 80, 75 and 77, the circular groove 71 and the second passages 70, the vanes 64 and the rotor 56 are rotated counterclockwise relative to the housing member 59 and the timing gear 55 in Fig 7 until the vanes 64 are contacted with the walls 59b1. Thereby, the valve timing control device is in the position of the maximum retarded condition in which the angular phase of the cam shaft 50 is retarded relative to that of the crank shaft 58 by a predetermined maximum value. Now, depending on the manner in which the control of the changeover valve 91 is executed, the vanes 64 can be stopped in any position (intermediate advanced position) between the maximum advanced position and the maximum retarded position. This requires that balance be achieved between the fluid pressure of the first pressure chambers 65 and the fluid pressure of the second pressure chambers 66 when the vanes 64 have achieved an arbitrary position. The amount of the advance can therefore be set to any value between a zero level and a maximum level. As mentioned above, the opening and closing timing of the valves (not shown) driven by the cam shaft 50 is adjusted and the angular phase difference between the crank shaft 58 and the cam shaft 50 is adjusted. Further, in this embodiment, since the grooves 67 and 68 which are extended in the axial direction are formed on the radially outer end portions of the opposed walls 59b1 and 59b2, respectively, it is able to obtain the same effects as the above first embodiment. Now, in this embodiment, the contacting portions between the front plate 60 and the housing member 59 and between the timing gear 55 and the housing member 59 are sealed by a metal touch, respectively. However, it is able to interpose a seal member which is bent so that the bolts 61 is located outside of the seal portion, respectively as shown in Fig. 2. Now, in this embodiment, the cam shaft 50 may be an exhaust cam shaft or may be an intake cam shaft. As mentioned above, according to the present invention, since the concave portions are formed on the radially outer end portions of the opposed walls of the chambers, respectively, even if the fluid which contains foreign matters is supplied to the chambers, the foreign matters are moved outwardly in the radial direction by the centrifugal force due to the rotation of the rotor and are collected into the concave portions. Accordingly, since it is prevented that the foreign matters are located between the vanes and the walls, the amount of the maximum advance or the maximum retard is always maintained at the predetermined amount. Further, if the foreign matters are located between the vanes and the walls and are collected, the foreign matters reach between the top end portion of the vanes and the outer circumferential walls of the chambers and the fluid-tightness between each of the first pressure chambers and each of the second pressure chambers deteriorates. In the present invention, however, since the foreign matters are always collected into the concave portions, it is able to exclude this bad effects due to the foreign matters and therefore it is able to maintain the good response of the valve timing control device.

Claims: A valve timing control device comprising: a rotor (17) adapted to be fixed on a cam shaft (2) of an engine; a housing member (19) adapted to be rotatably mounted on the cam shaft (2) so as to surround the rotor (17); at least one chamber (20) defined between the housing member (19) and the rotor (17) and having a pair of circumferentially opposed walls (19a1, 19a2); for each chamber (20), a vane (18) which is mounted on the rotor (17) and extends radially outwardly therefrom into the chamber (20) so as to divide the chamber (20) into a first pressure chamber (30) and a second pressure chamber (31); and means (38) for supplying fluid under pressure selectively to the or each first pressure chamber (30) or to the or each second pressure chamber (31); CHARACTERIZED IN THAT a dirt-collecting groove (36,37) is formed on the radially outer end of each of the opposed walls (19a1 or 19a2) of the or each chamber (20), facing the associated vane (18). A valve timing control device according to claim 1, wherein each groove (36,37) comprises a concave portion (36,37) at the radially outer end of each of the opposed walls (19a1, 19a2) of the or each chamber (20) which is extended in the axial direction. A valve timing control device according to claim 1 or claim 2, wherein any foreign matter which is contained in the fluid supplied to the first and second chambers (30,31) is collected into the grooves (36,37) by centrifugal force due to the rotation of the rotor (17). A valve timing control device according to any preceding claim, wherein the cam shaft (2) is one that is directly rotated by rotational torque from a crank shaft (48) of the engine, and the housing member (19) is adapted to be connected to another cam shaft (3) via a rotational torque transmitting means. A valve timing control device according to any preceding claim, further comprising a first passage means (43,26,45,12,29) for establishing fluid communication between the means (38) and the first pressure chamber (30) and a second passage means (44,47,27,46,13,28) for establishing fluid communication between the means (38) and the second pressure chamber (31), wherein at least one of the first and second passage means includes passages (46) which are formed in the cam shaft (2) so as to be extended outwardly from the axial centre of the cam shaft (2) in the radial direction. A valve timing control device according to claim 5, wherein the means (38) includes a fluid pump (40) from which fluid under pressure is supplied, an electromagnetic changeover valve (39) connected to the fluid pump (40) and selectively connectable to the first passage means (43,26,45,12,29) or to the second passage means (44,47,27,46,13,28) and a controller (41) for controlling the control position of the changeover valve (39). A valve timing control device according to any preceding claim, wherein a plurality of chambers (20) are defined between the housing member (19) and the rotor (17) and a plurality of vanes (18) are mounted on the rotor so that each vane (18) divides an associated one of the chambers (20) into a first pressure chamber (30) and a second pressure chamber (31). A valve timing control device according to any preceding claim, wherein the housing member (19) is adapted to be directly rotated by rotational torque from the crank shaft of the engine.

Inventors: AOKI KONGO, FUJIWAKI KENJI, KIRA NAOKI, SATO ATSUSHI, AOKI, KONGO, FUJIWAKI, KENJI, KIRA, NAOKI, SATO, ATSUSHI
Applicants: AISIN SEIKI, AISIN SEIKI KABUSHIKI KAISHA
Application year: 1996
Main classification: F01L1
IPC codes: F01L1