Abstract:
An engine includes a camshaft carrying a first intake cam, a second intake cam, and an exhaust cam for selectively driving an intake valve driving member and an exhaust valve driving member, which in turn drive an intake valve and an exhaust valve. The intake valve driving member includes first and second driving members, which form push rollers respectively in engagement with the first and second intake cams and a pressing section in engagement with the intake valve. The first and second driving members form bores communicating each other to form a hydraulic cylinder. First and second pistons are movable within the bores to selectively set the first and second driving members in a condition of being allowed to operate independently or in combination with each other.

Description:
TECHNICAL FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to a driving member of valve of engine, and more particularly to a structure of valve driving member of engine that simplifies engineering of variable lift of an engine valve. 
       DESCRIPTION OF THE PRIOR ART 
       [0002]      FIG. 1  of the attached drawings shows a conventional structure of valve variable-lift mechanism for an engine  1 , wherein first and second driving members  21 ,  22  are arranged above an engine valve  2 . The second driving member  22  is a multiple-link assembly. The first and second driving members  21 ,  22  may individually drive the engine valve  2  to realize variation of lift stroke of the engine valve  2 . In other words, when the engine valve  2  is driven by the first driving member  21 , the engine valve  2  is of a small lift opening condition, while when the engine valve  2  is driven by the second driving member  22 , the engine valve  2  is of a large lift opening condition. As such, switching of intake and exhaust valves can be realized for different lifts of engine valve  2  according to rotational speeds of the engine  1 . 
         [0003]    The conventional structure of valve variable-lift mechanism for the engine  1  described above uses the first and second driving members  21 ,  22  arranged above the engine valve  2  to individually drive the engine valve  2 . Although this is effective to realize switching of intake and exhaust valves for different lifts of engine valve  2  according to the rotational speeds of the engine  1 , yet the second driving member  22  is of a multiple-link assembly, which is complicated in structure and requires quite an amount of space for operation. Thus, the cylinder head  1   a  of the engine  1  must be enlarged in order to provide a sufficient amount of space for the operation of the second driving member  22 . Enlarging the cylinder head  1   a  of the engine  1  will certainly increase the cost of the engine  1  and also increase complication of engineering for the engine  1 . For a motorcycle or scooter, the amount of space provided for accommodating an engine  1  is very limited. Thus, it is desired to provide a structure-simplified valve variable-lift mechanism for engines and this is a major challenge of the motorcycle/scooter industry. 
       SUMMARY OF THE INVENTION 
       [0004]    The primary objective of the present invention is to provide a structure of driving member of valve of engine, wherein the engine comprises a crankcase, a cylinder block mounted on the crankcase, and a cylinder head mounted on the cylinder block. The cylinder head comprises an intake port and an intake valve and an exhaust port and an exhaust valve, and an oil control valve. A camshaft seat is arranged between the intake valve and the exhaust valve. The camshaft seat comprises a camshaft that is driven by a timing chain. The camshaft comprises a first intake cam, a second intake cam, and an exhaust cam mounted thereto. Through the first intake cam, the second intake cam, and the exhaust cam, the camshaft, when put in rotation, drives an intake valve driving member or an exhaust valve driving member, and further, through the intake valve driving member or the exhaust valve driving member, the intake valve or the exhaust valve is caused to take a lift for intake or exhaust operation. The intake valve driving member comprises a first driving member and a second driving member. The first driving member forms a positioning hole, a bore, and a push roller and the second driving member forms a positioning hole, a bore, a push roller, and a pressing section. The push roller of the first driving member is in engagement with the first intake cam and the push roller of the second driving member is in engagement with the second intake cam. Further, the pressing section of the second driving member is in engagement with the intake valve. The bore of the first driving member and the bore of the second driving member are in communication with each other to form a hydraulic cylinder. The hydraulic cylinder has two ends respectively closed by closure caps. The hydraulic cylinder receives therein a spring and first and second pistons. As such, the first driving member and the second driving member can be selectively driven to operate independent of each other or in combination with each other to vary the lift of an engine intake valve thereby simplifying the engineering of variable lift for engine intake vale. 
         [0005]    Another objective of the present invention is to provide a structure of driving member of valve of engine, wherein a position-constraining mechanism is arranged above the cylinder head and the position-constraining mechanism comprises a position-constraining rod, a spring, and a pressure relief hole, whereby with the position-constraining mechanism being in pushing engagement with the first driving member and the second driving member the positioning bar, it is ensured that the bores of the first and second driving members can be set at predetermined locations. 
         [0006]    A further objective of the present invention is to provide a structure of driving member of valve of engine, wherein the first driving member and the second driving member comprise positioning bars that are located between the positioning holes and the pressing section and the bores of the first and second driving members are located between the push rollers and the positioning holes and located above a center-connection line connecting between centers of the push rollers and the positioning holes whereby the overall height of the cylinder head is effectively reduced. 
         [0007]    The foregoing objectives and summary provide only a brief introduction to the present invention. To fully appreciate these and other objects of the present invention as well as the invention itself, all of which will become apparent to those skilled in the art, the following detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. Throughout the specification and drawings identical reference numerals refer to identical or similar parts. 
         [0008]    Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is schematic view showing a conventional cylinder head. 
           [0010]      FIG. 2  is a perspective view illustrating an engine cylinder head according to the present invention. 
           [0011]      FIG. 3  is a cross-sectional view of a portion of the cylinder head according to the present invention. 
           [0012]      FIG. 4  is a perspective view illustrating a camshaft according to the present invention. 
           [0013]      FIG. 5  is a top view of the cylinder head according to the present invention. 
           [0014]      FIG. 5A  is an enlarged view of a circled portion of  FIG. 5 . 
           [0015]      FIG. 6  is a perspective view illustrating an exhaust valve driving member according to the present invention. 
           [0016]      FIG. 7  is an exploded view illustrating an intake valve driving member according to the present invention. 
           [0017]      FIG. 7A  is a cross-sectional view of a first piston according to the present invention. 
           [0018]      FIGS. 8 and 9  are schematic views illustrating the operation of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    The following descriptions are exemplary embodiments only, and are not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention as set forth in the appended claims. 
         [0020]    Referring to  FIG. 2 , the present invention provides an engine  3 , which comprises a crankcase  31 , a cylinder block  32  that is mounted on the crankcase  31 , and a cylinder head  33  that is mounted on the cylinder block  32 . 
         [0021]    The crankcase  31  comprises a crankshaft (not shown) arranged therein. The crankcase  31  comprises an oil pump  311  arranged therein. The oil pump  311  pumps oil to a primary oil supply passage  312 . The primary oil supply passage  312  extends from the crankcase  31  through the cylinder block  32  to communicate an oil control valve  4  that is mounted to the cylinder head  33 . 
         [0022]    The cylinder block  32  is mounted on the crankcase  31  and receives a timing chain  5  to extend therethrough. The cylinder block  32  comprises a timing chain tensioner  51  that is arranged at a side corresponding to an intake port  331  of the cylinder head  33 . 
         [0023]    The cylinder head  33  comprises the intake port  331  that is arranged at an intake side and an intake valve  332  and an exhaust port  333  that is arranged at an exhaust side and an exhaust valve  334 . Referring to  FIGS. 2 ,  3 ,  4 ,  5 , and  5 A, the cylinder head  33  comprises a camshaft seat  335  that is integrally formed between the intake valve  332  and the exhaust valve  334 . The camshaft seat  335  comprises a camshaft  336  that is driven by the timing chain  5 . The camshaft  336  comprises a first intake cam (high lift cam)  3361 , a second intake cam (low lift cam)  3362 , and an exhaust cam  3363  mounted thereto. Through the first intake cam  3361 , the second intake cam  3362 , and the exhaust cam  3363 , the camshaft  336 , when in rotation, may drive an intake valve driving member  6  and an exhaust valve driving member  7  of the intake valve  332  and the exhaust valve  334 . Referring to  FIGS. 3 ,  5 ,  5 A, and  6 , the exhaust valve driving member  7  has an end forming a pressing section  71 , which is in engagement with the exhaust valve  334  and has an end forming a gap adjusting member  711 , and an opposite end forming a push roller  72 , which is in engagement with the exhaust cam  3363 . A bearing sleeve  73  extends sideways from a side of the exhaust valve driving member  7  for receiving the extension of a shaft rod  74  therethrough. Through the shaft rod  74 , the exhaust valve driving member  7  is securely positioned on the camshaft seat  335 , whereby the exhaust cam  3363  of the camshaft  336  may drive the push roller  72  to have the pressing section  71  pressing the exhaust valve  334  for opening the exhaust valve to discharge exhaust gas. A gap between the pressing section  71  and the exhaust valve  334  can be adjusted through the gap adjusting member  711  in order to ensure the exhaust valve  334  has a desired lift stroke. Further, referring to  FIGS. 3 ,  5 ,  5 A,  7 , and  7 A, the intake valve driving member  6  comprises a first driving member  61  and a second driving member  62 . The first driving member  61  forms in a front portion thereof a positioning hole  611 , a positioning bar  612  being arranged to project from a front lower side of the positioning hole  611 , and also forms a through bore  613  at a location behind the positioning hole  611 , a push roller  614  being arranged behind the bore  613 . Corresponding to the first driving member  61 , the second driving member  62  forms, in sequence, a positioning hole  621 , a positioning bar  622 , a through bore  623 , and a push roller  624 . Further, the second driving member  62  comprises a pressing section  625  extending from a front side of the positioning hole  621  and the pressing section  625  has a front end forming a gap adjusting member  6251 . The push roller  614  of the first driving member  61  is set in engagement with the first intake cam  3361  of the camshaft  336 , while the push roller  624  of the second driving member  62  is in engagement with the second intake cam  3362  of the camshaft  336 . Further, the pressing section  625  of the second driving member  62  is in engagement with the intake valve  332 . A gap between the pressing section  625  and the intake valve  332  can be adjusted through the gap adjusting member  6251  in order to ensure that the intake valve  332  has a desired lift stroke. Further, with a shaft rod  63  received through the positioning holes  611 ,  621 , the first driving member  61  and the second driving member  62  are securely positioned on the camshaft seat  335 , whereby the first driving member  61  and the second driving member  62  are reciprocally rotatable about a center defined by the shaft rod  63 . Further, as shown in  FIG. 3 , the positioning bars  612 ,  622  of the first driving member  61  and the second driving member  62  are respectively arranged at locations between the positioning holes  611 ,  621  and the pressing section  625 . The bores  613 ,  623  of the first driving member  61  and the second driving member  62  are located between the push rollers  614 ,  624  and the positioning holes  611 ,  621  and are located above a center-connection line A connecting between centers of the push roller  614 ,  624  and the positioning holes  611 ,  621  so as to effectively reduce the overall height of the cylinder head  33 . Referring to  FIGS. 5 ,  5 A,  7 ,  7 A,  8 , and  9 , the bore  613  of the first driving member  61  and the bore  623  of the second driving member  62  are arranged to connect to and communicate each other to collectively form a hydraulic cylinder  64 . The hydraulic cylinder  64  has opposite ends that are respectively closed and sealed by closure caps  641   a ,  641   b . Each of the closure caps  641   a ,  641   b  forms a projecting peg  6411   a ,  6411   b  extending inward of the hydraulic cylinder  64 . The hydraulic cylinder  64  receives therein a spring  642  and a first piston  643  and a second piston  644 , which are hydraulically movable by oil pressure. The hydraulic cylinder  64  is connected through driving oil passages  65 ,  66  to the oil control valve  4  in order to receive hydraulic power therefrom. Further, the first piston  643  has two ends respectively forming a first recess  6431  and a second recess  6432  for the purposes of reducing weight of the first piston  643  and thus enhancing movability of the first piston  643  within the hydraulic cylinder  64 . The first recess  6431  is shaped to receive the projecting peg  6411   a  of the closure cap  641   a  therein and the projecting peg  6411   b  of the closure cap  641   b  is engageable with an end of the second piston  644 , whereby the first piston  643  and the second piston  644  are spaced from the ends of the hydraulic cylinder  64  by distances to allow oil flowing through the driving oil passages  65 ,  66  into the hydraulic cylinder  64  may reliably move the first piston  643  and the second piston  644 . Further, with the projecting pegs  6411   a ,  6411   b  of the closure caps  641   a ,  641   b , the first piston  643  and the second piston  644  are positionable at predetermined locations during their operations so as to ensure the movability of the first piston  643  and the second piston  644  within the hydraulic cylinder  64 . Further, the cylinder head  33  is provided, at a location below the positioning bars  612 ,  622 , with a position-constraining mechanism  337 . The position-constraining mechanism  337  comprises a position-constraining rod  3371 , a spring  3372 , and a pressure relief hole  3373 . The position-constraining mechanism  337  is provided for supporting pushing engagement of the positioning bars  612 ,  622  in order to ensure that the bore  613  of the first driving member  61  and the bore  623  of the second driving member  62  can be set at predetermined locations. Further, when the position-constraining mechanism  337  is acted upon by undue pushing forces applied by the positioning bars  612 ,  622 , the pressure relief hole  3373  is timely opened to release pressure in order to ensure the movability of the first piston  643  and the second piston  644  within the hydraulic cylinder  64 . 
         [0024]    To practice the present invention, as shown in  FIGS. 2 ,  3 ,  8 , and  9 , the oil pump  311  arranged in the crankcase  31  pumps oil to the primary oil supply passage  312 , which extends from the crankcase  31  through the cylinder block  32  to communicate the oil control valve  4  that is mounted to the cylinder head  3 , wherein the oil control valve  4  supplies the oil into the driving oil passages  65 ,  66  of the cylinder head  33  to feed into the hydraulic cylinder  64 . Further, as shown in  FIGS. 8 and 9 , through detection of traveling condition of a vehicle by an ECU (not shown) of the engine  3 , if it is determined that the engine valve requires only low lift opening, the ECU of the engine  3  instructs the oil control valve  4  to feed the oil through the driving oil passage  65  into the hydraulic cylinder  64 , as shown in  FIG. 8 , whereby through the oil pressure and a spring force of the spring  642 , the first piston  643  and the second piston  644  are moved in a direction toward the first driving member  61 . The oil, after flowing through the driving oil passage  65  into the bore  621  of the second driving member  62 , is guided by the projecting peg  6411  of the closure cap  641   a  and the first piston  643  into the recess  6431  of the first piston  643 , and at the same time, the oil contained in the first driving member  61  is forced to discharge through the driving oil passage  66 , whereby the second piston  644  is moved to locate within the first driving member  61  and is positioned at a predetermined location by the projecting peg  6411   b  of the closure cap  6411   b  at the side corresponding to the first driving member  61  and the first piston  643  is located in the second driving member  62 . Under this condition, the first driving member  61  and the second driving member  62  are allowed to rotate independent of each other. Since the pressing section  625  at the front end of the second driving member  62  is in engagement with the intake valve  332  and the push roller  624  at the rear end of the second driving member  62  is in engagement with the second intake cam (low lift cam)  3362  of the camshaft  336 , the intake valve  332  of the engine  3  is set in a low lift opening condition. Further; when the engine  3  is switched, due to change of vehicle traveling condition, to a high lift opening condition for the intake valve, the ECU of the engine  3  instructs the oil control valve  4  to feed oil through the driving oil passage  66  into the hydraulic cylinder  64 , as shown in  FIG. 9 , whereby the oil flows through the driving oil passage  66  into the bore  613  of the first driving member  6  and at the same time, the oil contained in the bore  623  of the second driving member  62  is discharged. Through the oil pressure, the first piston  643  and the second piston  644  are moved in a direction toward the second driving member  62  to have the first piston  643  located in the second driving member  62  and through the constrain imposed by the projecting peg  6411   a  of the closure cap  641   a  of the second driving member  62 , the first piston  643  and the second piston  644  are located at predetermined locations where the second piston  644  is set between the first driving member  61  and the second driving member  62 , whereby the first driving member  61  and the second driving member  62  are coupled to each other. Since the push roller  614  at the rear end of the first driving member  61  is in engagement with the first intake cam (high lift cam)  3361  of the camshaft  336  and the pressing section  625  at the front end of the second driving member  62  is in engagement with the intake valve  332 , the second driving member  62  is moved by the first driving member  61  to set the intake valve  332  to a desired high lift opening condition according to the lift of the first intake cam (high lift cam)  3361 . As such, variable valve lift of the engine  3  can be realized. 
         [0025]    Efficacies of the present invention are that the camshaft  336  is provided with the first intake cam  3361 , the second intake cam  3362 , and the exhaust cam  3363 , and the intake valve driving member  6  comprises the first driving member  61  and the second driving member  62 , and further, the bore  613  of the first driving member  61  and the bore  623  of the second driving member  62  are in communication with each other to form the hydraulic cylinder  64 , with the spring  642  and the first piston  643  and the second piston  644  that are movable hydraulically and by the spring  642  being contained within the hydraulic cylinder  64 , the first driving member  61  and the second driving member  62  are selectively rotatable independent of each other or in combination with each other to vary lift stroke of the intake valve  332  of the engine  3 , and thus simplifying engineering of variable lift for the engine valve  332  of the engine  3 . Further, with the positioning bars  612 ,  622  of the first driving member  61  and the second driving member  62  located between the positioning holes  611 ,  621  and the pressing section  625  and with the bores  613 ,  623  of the first driving member  61  and the second driving member  62  located between the push rollers  613 ,  6232  and the positioning holes  611 ,  621  and located above the center-connection line A connecting between centers of the push rollers  614 ,  624  and the positioning holes  611 ,  621 , the overall height of the cylinder head  33  is effectively reduced. 
         [0026]    It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of methods differing from the type described above. 
         [0027]    While certain novel features of this invention have been shown and described and are pointed out in the annexed claim, it is not intended to be limited to the details above, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the spirit of the present invention.