Abstract:
An oil control valve includes a cylindrical valve housing and ports and formed in a periphery of the valve housing so as to face pipes, respectively, that guide hydraulic oil to an actuator. The valve housing is provided with a groove that provides communication between the port and the pipeline and a groove that provides communication between the port and the pipeline.

Description:
CROSS-REFERENCE TO THE RELATED APPLICATION 
     This application is a continuation of International Application No. PCT/JP99/05020, whose international filing date is Sep. 14, 1999, the disclosures of which Application are incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an oil control valve for supplying hydraulic oil to a blade oil hydraulic actuator for controlling an intake valve or exhaust valve to open or close timely depending on the operating condition of an engine so as to control the oil level of the oil hydraulic actuator. 
     2. Description of the Related Art 
     FIG. 1 is a sectional diagram showing a blade oil hydraulic actuator according to the related art. Reference numeral  1  indicates an intake cam shaft (hereinafter, simply referred to as a cam shaft) provided with an intake cam  1   a.  Numeral  2  indicates a timing pulley provided at an end of the cam shaft  1 . Numeral  3  indicates an actuator coupled to the cam shaft  1  so as to control valve opening/closing timing. Hydraulic oil supplied to drive the actuator  3  is lubricating oil for the engine (not shown). The actuator  3  is driven by the hydraulic oil to vary a displacement angle of the cam shaft  1  so that the opening and closing timing of the intake valve (not shown) is continuously controlled. Numeral  4  indicates a bearing of the cam shaft  1 . Numeral  5  indicates a housing of the actuator  3  and is rotatably fitted to the cam shaft  1 . 
     Numeral  6  indicates a case secured to the housing  5 . Numeral  7  indicates a blade rotor connected to the cam shaft  1  by a bolt  8  and housed in the case  6 . The rotor  7  is rotatable with respect to the case  6 . Numeral  9  indicates a tip seal provided between the case  6  and the rotor  7  so as to prevent leakage of oil between oil hydraulic chambers bounded by the case  6  and the rotor  7 . Numeral  10  indicates a back spring formed of a flat spring for forcing the tip seal  9  to be in contact with the rotor  7 . Numeral  11  indicates a cover secured to the case  6 . Numeral  12  indicates a bolt securing the housing  5 , the case  6  and the cover  11  to each other. Numeral  13  indicates an O-ring. Numeral  14  indicates a plate. Numeral  15  indicates a bolt securing the plate  14  to the cover  11 . Numerals  16  and  17  indicate O-rings. Numeral  18  indicates a cylindrical holder provided in the rotor  7 . An engagement hole  18   a , for engaging a plunger described later therewith is provided in the holder  18  to extend in an axial direction. 
     Numeral  19  indicates a plunger slidably provided in the housing  5  and provided with an engagement shaft portion  19   a  fitted within the hole  18   a  of the holder  18 . Numeral  20  indicates a spring for urging the plunger  19  toward the holder  18 . Numeral  21  indicates a plunger oil passage for introducing the hydraulic oil into the engagement hole  18   a  of the holder  18 . The hydraulic oil introduced into the engagement hole  18   a  of the holder  18  via the plunger oil passage  21  displaces the plunger  19  against the urging force of the spring  20  so that the holder  18  is released from the locking action provided by the plunger  19 . Numeral  22  indicates an air vent. Numeral  22  indicates an air vent. Numeral  23  indicates a shaft bolt for securing the rotor  7  to the cam shaft  1 . Numeral  24  indicates an air vent. 
     Numeral  25  indicates a first oil passage provided in the cam shaft  1  and the rotor  7  to communicate with a lag oil hydraulic chamber (not shown) for displacing the rotor  7  in a lagging direction. Numeral  26  indicates a second oil passage provided in the cam shaft  11  and the rotor  7  to communicate with an advance oil hydraulic chamber (not shown) for displacing the rotor  7  in an advancing direction. 
     Numeral  27  indicates a oil control valve (hereinafter, referred to as OCV) for supplying hydraulic oil to the actuator  3  and controlling the quantity of the oil supplied. Numeral  28  indicates a substantially cylindrical valve housing having a port corresponding to an open end of pipelines  32 - 35  described later. Numeral  29  indicates a spool that slides in the valve housing  28  in an axial direction of the valve housing  28 . Numeral  30  indicates a spring that urges the spool in one direction. Numeral  31  indicates a linear solenoid for actuating the spool  29  against the urging force of the spring  30 . Numeral  32  indicates a supply pipeline for guiding the hydraulic oil supplied via an oil pump described later to the valve housing  28 . Numeral  33  indicates a drain pipeline for returning the hydraulic oil inside the valve housing  28  to an oil pan described later. Numeral  34  indicates a first pipeline for guiding the hydraulic oil to the first oil passage  25 . Numeral  35  indicates a second pipeline for guiding the hydraulic oil to the second oil passage  26 . Numeral  36  indicates an oil pan. Numeral  37  indicates an oil pump. Numeral  38  indicates an oil filter for eliminating impurities from the hydraulic oil. The oil pan  36 , the oil pump  37  and the oil filter  38  constitute a lubricating system for lubricating various parts o the engine (not shown). The oil pan  36 , the oil pump  37 , the oil filter  38  and the OCV  27  constitute a system for supplying the hydraulic oil to the actuator  3 . 
     Numeral  39  indicates an engine block provided with a recess for accommodating the valve housing  28 . The interior of the recess of the engine block  39  houses the pipelines  32 - 35  so as to allow open ends of the pipelines  32 - 35  to face respective ports of the valve housing  28 . 
     Numeral  40  indicates an electronic control unit (ECU). The ECU controls fuel injection quantity, ignition timing and valve opening/closing timing by actuating an injector, ignitor and the OCV  27  based on signals from an intake air quantity sensor (not shown), a throttle sensor (not shown), a water temperature sensor (not shown), a crank angle sensor (not shown) and a cam angle sensor (not shown). The ECU also controls the OCV  27  closing timing subsequent to turning off of the ignition switch. 
     A description will now be given of the operation of the actuator  3  and the OCV  27 . 
     When the engine is at a stop, the rotor  7  is at a position with a maximum lagging displacement. That is, the rotor  7  is rotated by a maximum advance angle with respect to the housing  5 . The oil pump  37  is not in operation so that the hydraulic oil is not supplied to the first oil passage  25 , the second oil passage  26  and the plunger oil passage  21 . The pressure of the oil retained inside the actuator  3  is relatively low. Therefore, the plunger  19  is thrust against the holder  18  by the urging force of the spring  20 . The engagement shaft portion  19   a  of the plunger  19  is engaged with the engagement hole  18   a  of the holder  18  so that the housing  5  and the rotor  7  remains locked to each other. 
     When the engine is started in this locked state, the oil pump  37  is put into operation so that the pressure of the hydraulic oil supplied to the OCV  27  is increased. The hydraulic oil is supplied by the OCV  27  to the lag oil hydraulic chamber (not shown) in the actuator  3  via the first pipeline  34  and the first oil passage  25 . Due to the pressure built up in the lag oil hydraulic chamber, a slide plate (not shown) is displaced toward the advance oil hydraulic chamber (not shown) so that the lag oil hydraulic chamber and the plunger oil passage  21  communicate with each other. The hydraulic oil is supplied from the plunger  21  to the engagement hole  18   a  of the holder  18  and the plunger  19  is then thrust against the urging force of the spring  20 . As a result of this, the engagement shaft portion  19   a  of the plunger  19  is pulled out of the engagement hole  18   a  of the holder  18  so that the plunger  19  and the rotor  7  become disengaged. 
     Subsequently, the hydraulic oil is supplied by the OCV  27  to the advance oil hydraulic chamber (not shown) via the second pipeline  35  and the second oil passage  26  so as to advance the rotor  7 . The oil pressure is transmitted to the plunger oil passage  21  SO as to displace the plunger  19  toward the housing  5  against the urging force of the spring  20 , thus disengaging the plunger  19  and the holder  18 . The OCV  27  is operated (opened or closed) in this disengaged state so as to control the quantity of oil supplied to the lag oil hydraulic chamber and the advance oil hydraulic chamber, thus controlling the rotation of the rotor  7  with respect to the housing  5 . The pressure of the oil supplied via the OCV  27  is subject to feedback control and computation by the ECU  40 , in accordance with signals from a position sensor (not shown) for detecting a relative angle of rotation of the rotor  7  with respect to the housing  5  and a crank angle sensor (not shown) for determining the oil pressure applied by the oil pump  37 . 
     In the related-art oil hydraulic actuator described above, when the valve housing  28  of the OCV  27  is introduced into the engine block  39  for installation, the open ends of the pipelines  32 - 35 , provided in the engine block  39  so as to face the respective ports formed in the valve housing  28 , may be displaced with respect to the respective ports, in a circumferential or axial direction of the valve housing  28 . This results in communication between the pipelines  32 - 35  and the respective ports being obstructed so that the quantity of flow of the hydraulic oil is reduced. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide an OCV in which the drawback of the related art is eliminated. 
     Another and more specific object of the invention is to obtain an OCV provided with a valve housing capable of preventing reduction in the quantity of flow of the hydraulic oil even when the ports are displaced in position with respect to the pipelines. 
     The aforementioned objects can be achieved by an oil control valve for controlling supply of hydraulic oil to an oil hydraulic actuator via a plurality of pipelines, comprising: a cylindrical housing; a plurality of ports formed in a periphery of said housing so as to correspond to the plurality of pipelines; and grooves provided in the periphery of said housing so as to provide communication between an associated port and an associated pipeline. With this, even when displacement occurs between the pipeline and the port of the valve housing, the grooves ensure communication between the pipeline and the port. Thereby, reduction in the quantity of hydraulic oil is prevented. 
     The groove may be formed to extend from a bottom of the port to cover an entirety of the periphery of said housing. With this, even when displacement, in a circumferential direction of the valve housing, occurs between the pipeline and the port of the valve housing, the groove ensures communication between the pipeline and the port so that reduction in the quantity of hydraulic oil is prevented. 
     The groove, formed around the entirety of the valve housing, may have a width smaller than that of the port. With this, even when displacement between the pipeline and the port of the valve housing occurs, communication between the pipeline and the port is ensured so that reduction in the quantity of hydraulic oil is prevented. 
     The groove, formed around the entirety of the valve housing, may have a width identical to that of the port. With this, even when displacement, in a circumferential direction of the valve housing, occurs between the pipeline and the port of the valve housing, any portion of the groove, provided around the entirety of the valve housing, is available to replace the port for supply of the hydraulic oil. Accordingly, reduction in the quantity of hydraulic oil is successfully prevented. 
     The groove, formed around the entirety of the valve housing, may have a width larger than that of the port. With this, any portion of the groove, provided around the entirety of the valve housing, is available to replace the port for supply of the hydraulic oil. Accordingly, reduction in the quantity of hydraulic oil is successfully prevented. 
     The groove may extend from an edge of the port in an axial direction of said housing. With this, even when displacement, in an axial direction of the valve housing, occurs between the pipeline and the port of the valve housing, communication between the pipeline and the port is ensured so that reduction in the quantity of the hydraulic oil is prevented. 
     The groove, extending from an edge of the port in an axial direction of said housing, may include a taper inclined from the periphery of said housing toward a surface of the port. With this, even when displacement, in an axial direction of the valve housing, occurs between the pipeline and the port of the valve housing, the taper ensures communication between the pipeline and the port so that reduction in the quantity of the hydraulic oil is prevented. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a sectional view showing an oil control valve in the related-art oil hydraulic actuator; 
     FIG. 2 is a sectional view showing an oil control valve according to a first embodiment of the present invention; 
     FIGS. 3A-3E show a portion of the oil control valve shown in FIG. 2, FIG. 3A being a top view, FIG. 3B being a front view, FIG. 3C being a bottom view, FIG. 3D being a saggital sectional view taken at a line A—A, line C—C or line E—E of FIG. 3B, and FIG. 3E being a saggital sectional view taken at a line B—B or line D—D of FIG. 3B; 
     FIG. 4 is an enlarged front view showing displacement of a port in the oil control valve shown in FIG. 2 with respect to a pipeline of an engine block; 
     FIG. 5 is a sectional view showing the oil control valve according to a second embodiment; 
     FIGS. 6A-6E show a portion of the oil control valve shown in FIG. 5, FIG. 6A being a top view, FIG. 6B being a front view, FIG. 6C being a bottom view, FIG. 6D being a saggital sectional view taken at a line A—A, line C—C or line E—E of FIG. 6B, and FIG. 6E being a saggital sectional view taken at a line B—B or line D—D of FIG. 6B; 
     FIG. 7 is an enlarged front view showing displacement of a port in the oil control valve shown in FIG. 5 with respect to a pipeline of an engine block; 
     FIG. 8 is an enlarged front view showing displacement of a port in the oil control valve according to a variation of the second embodiment with respect to a pipeline of an engine block; 
     FIG. 9 is a sectional view showing the oil control valve according to a third embodiment; 
     FIGS. 10A-10E show a portion of the oil control valve shown in FIG. 9, FIG. 10A being a top view, FIG. 10B being a front view, FIG. 10C being a bottom view, FIG. 10D being a saggital sectional view taken at a line A—A or line E—E of FIG. 10B, and FIG. 10E being a saggital sectional view taken at a line B—B, line C—C or line D—D of FIG. 10B; and 
     FIG. 11 is an enlarged front view showing displacement of a port in the oil control valve shown in FIG. 9 with respect to a pipeline of an engine block. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A detailed description will now be given of the best mode for carrying out the present invention, with reference to the attached drawings. 
     FIRST EMBODIMENT 
     FIG. 2 is a sectional view showing an oil control valve according to a first embodiment of the present invention. FIGS. 3A-3E show a portion of the oil control valve shown in FIG. 2, FIG. 3A being a top view, FIG. 3B being a front view, FIG. 3C being a bottom view, FIG. 3D being a saggital sectional view taken at a line A—A, line C—C or line E—E of FIG. 3B, and FIG. 3E being a saggital sectional view taken at a line B—B or line D—D of FIG.  3 B. FIG. 4 is an enlarged front view showing displacement of a port in the oil control valve shown in FIG. 2 with respect to a pipeline of an engine block. Those elements that constitute the oil control valve according to the first embodiment that are substantially identical to those constituting elements of the oil control valve according to the related art shown in FIG. 1 are designated by the same reference numerals and the description thereof is omitted. 
     Referring to figures, numeral  41  indicates a port formed in the valve housing  28  so as to correspond to the first pipeline  34 ;  42  indicates a port formed in the valve housing  28  so as to correspond to the second pipeline  35 ;  43  indicates a port formed in the valve housing  28  so as to correspond to the supply pipeline  32 ;  44  indicates a port formed in the valve housing  28  so as to correspond to the drain pipeline  33 ;  45  and  46  indicate annular grooves (hereinafter, referred to as peripheral grooves) that communicate with the ports  41  and  42 , respectively, and extending in the periphery of the valve housing  28  in a circumferential direction thereof. The width of the peripheral grooves  45  and  46  is smaller than that of the ports  41  and  42 . That is, the width of the peripheral grooves  45  and  46  is smaller than the length of the ports  41  and  42  in an axial direction of the valve housing  28 . 
     Referring to the figures, numeral  61  indicates a bracket;  62  and  63  indicate sleeves;  64  indicates a rod;  65  indicates a case;  66  indicates a bobbin;  67  indicates a core;  68  indicates a spacer;  69  indicates an O ring;  70  indicates a cover;  71  indicates a terminal;  72  indicates a plunger;  73  indicates a boss; and  74 - 76  indicate O rings. 
     According to the first embodiment, even when an open end F of the first pipeline  34  is displaced as shown in FIG. 4 with respect to the port  41  in a circumferential direction of the valve housing  28 , communication between the open end F and the port  41  is maintained since the open end F communicates with the peripheral groove  45  communicating with the port  41 . Thus, reduction in the quantity of hydraulic oil in the first pipeline  34  and the second pipeline  35  is prevented. 
     In the description of the first embodiment given above, it is assumed that the peripheral grooves  45  and  46  are provided in the ports  41  and  42 , respectively. However, the port  43  may also be provided with a peripheral groove. In this case, reduction in the quantity of hydraulic oil supplied from the oil pump  37  is prevented. 
     SECOND EMBODIMENT 
     FIG. 5 is a sectional view showing the oil control valve according to a second embodiment. FIGS. 6A-6E show a portion of the oil control valve shown in FIG. 5, FIG. 6A being a top view, FIG. 6B being a front view, FIG. 6C being a bottom view, FIG. 6D being a saggital sectional view taken at a line A—A, line C—C or line E—E of FIG. 6B, and FIG. 6E being a saggital sectional view taken at a line B—B or line D—D of FIG.  6 B. FIG. 7 is an enlarged front view showing displacement of a port in the oil control valve shown in FIG. 5 with respect to a pipeline of an engine block. Those elements that constitute the oil control valve according to the second embodiment that are substantially identical to those constituting elements of the oil control valve according to the related art or the first embodiment are designated by the same reference numerals and the description thereof is omitted. 
     The feature of the second embodiment is that the width of the peripheral grooves  45  and  46  is the same as the width of the ports  41  and  42 , respectively. As shown in FIG. 7, as a result of this arrangement, even when the open end F of the first pipeline  34  is displaced with respect to the port  41  in a circumferential direction of the valve housing  28 , communication between the open end F and the port  41  is maintained since the open end F communicates with the peripheral groove  45  communicating with the port  41 . The second embodiment is advantageous in that, in case of displacement, in a circumferential direction of the valve housing  28 , between the first pipeline  34  and the port  41  of the housing  28  or between the second pipeline  35  and the port  42  of the housing  28 , any portion of the groove, provided around the entirety of the valve housing  28 , is available to replace the port  41  or port  42  for supply of the hydraulic oil. Accordingly, reduction in the quantity of hydraulic oil is successfully prevented. 
     In the description of the second embodiment given above, it is assumed that the peripheral grooves  45  and  46  are provided in the ports  41  and  42 , respectively. However, the port  43  may also be provided with a peripheral groove. In this case, reduction in the quantity of hydraulic oil supplied from the oil pump  37  is prevented. 
     Variation 
     FIG. 8 is an enlarged front view showing displacement of a port in the oil control valve according to a variation of the second embodiment with respect to a pipeline of an engine block. 
     The feature of the variation of the second embodiment is that the width of the peripheral grooves  45  and  46  is larger than that of the ports  41  and  42 . As shown in FIG. 8, as a result of this arrangement, even when the open end F of the first pipeline  34  is displaced with respect to the port  41  in a circumferential direction of the valve housing  28 , communication between the open end F and the port  41  is maintained since the open end F communicates with the peripheral groove  45  communicating with the port  41 . This variation is advantageous in that, in case of displacement, in a circumferential direction of the valve housing  28 , between the first pipeline  34  and the port  41  of the housing  28  or between the second pipeline  35  and the port  42  of the housing  28 , any portion of the groove, provided around the entirety of the valve housing  28 , is available to replace the port  41  or port  42  for supply of the hydraulic oil. Accordingly, reduction in the quantity of hydraulic oil is successfully prevented. 
     THIRD EMBODIMENT 
     FIG. 9 is a sectional view showing the oil control valve according to a third embodiment. FIGS. 10A-10E show a portion of the oil control valve shown in FIG. 9, FIG. 10A being a top view, FIG. 10B being a front view, FIG. 10C being a bottom view, FIG. 10D being a saggital sectional view taken at a line A—A or line E—E of FIG. 10B, and FIG. 10E being a saggital sectional view taken at a line B—B, line C—C or line D—D of FIG.  10 B. FIG. 11 is an enlarged front view showing displacement of a port in the oil control valve shown in FIG. 9 with respect to a pipeline of an engine block. Those elements that constitute the oil control valve according to the third embodiment that are substantially identical to those constituting elements of the oil control valve according to the related art or the first embodiment are designated by the same reference numerals and the description thereof is omitted. 
     The feature of the third embodiment is that, instead of providing the peripheral grooves in the valve housing  28  as in the first or second embodiment, tapers  47 ,  48  and  49  are provided adjacent to the ports  41 ,  42  and  43 , respectively, in an axial direction of the valve housing  28 . The tapers  47 ,  48  and  49  function to extend the width of the ports  41 ,  42  and  43 , respectively. Therefore, as shown in FIG. 11, the in case of displacement, in an axial direction of the valve housing  28 , between the port  41  and the open end F of the first pipeline  34 , obstruction of communication between the pipeline and the port is prevented so that reduction in the quantity of the hydraulic oil is prevented. 
     In the foregoing description of the third embodiment, a taper is employed as a groove (hereinafter, referred to as a breadth groove) for extending the width of the port. Alternatively, a groove of any configuration may be employed as long as it extends from an edge of the port in an axial direction of the valve housing  28 . 
     In the foregoing description of the first through third embodiments, the peripheral grooves or the breadth grooves are discussed as means for mediating communication between the port and the pipeline. Alternatively, the peripheral grooves and breadth grooves may be used in combination so as to achieve the effect of further preventing reduction in the quantity of hydraulic oil. 
     The OCV according to any of the first through third embodiments may be built into the actuator  3  of the related art shown in FIG.  1 . In this case, even when displacement occurs between the port of the valve housing  28  and the pipeline of the engine block when building the OCV into the actuator  3 , reduction in the quantity of the hydraulic oil is prevented due to the operation of the OCV according to any of the first through third embodiments. Therefore, normal operation of the oil hydraulic actuator is ensured. 
     The oil control valve according to the present invention is advantageously applied in that, even when displacement occurs between the port of the valve housing and the pipeline in the engine block, grooves ensure communication between the port and the pipeline. Accordingly, reduction in the quantity of hydraulic oil is prevented. The oil control valve of this construction finds a useful application in the oil hydraulic actuator. 
     The present invention is not limited to the above-described embodiments, and variations and modifications may be made without departing from the scope of the present invention.