JP4344716B2 - Valve operating device for internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine in which a base end portion of a rocker arm having a cam abutting portion that comes into contact with a cam provided on a camshaft is rotatably supported by a cylinder head, and a tip end portion of the rocker arm abuts against an engine valve. The present invention relates to a valve gear.

A valve operating device in which a base end portion is rotatably supported by a fixed rocker shaft and a tip end portion of a rocker arm that swings following the cam of a camshaft is brought into contact with an engine valve. It is already known from US Pat.
JP 2003-97227 A

  By the way, the valve clearance between the engine valve and the rocker arm and the lift amount of the engine valve are very small, and if the valve clearance or the lift amount varies, the intake or exhaust amount may vary greatly. Although it is required to deal with precision work, a highly rigid structure and adjustment mechanism, etc., even if there is no variation in valve clearance and lift amount due to such measures, the shape of the piston and cylinder bore, the state of the piston ring, Variations in intake or exhaust amount remain due to variations in intake or exhaust flow resistance.

  Therefore, it is necessary to adjust the valve clearance and lift amount of the engine valve while checking the actual intake or exhaust amount by operating the engine. In that case, the mechanism that makes it possible to adjust the valve clearance and lift amount during engine operation It is required to prevent the weight of the movable part from being increased by providing.

  The present invention has been made in view of such circumstances, and provides a valve operating apparatus for an internal combustion engine in which the valve clearance and lift amount of the engine valve can be adjusted during engine operation with a configuration that does not increase the weight of the movable part. The purpose is to do.

In order to achieve the above object, according to the first aspect of the present invention, a base end portion of a rocker arm having a cam abutting portion that comes into contact with a cam provided on a camshaft is rotatably supported by a cylinder head. a valve operating system for an internal combustion engine the tip is brought into contact with the engine valve, to vary the swing fulcrum of the rocker arm during operation of the engine in response to an external operation of the head cover coupled to said cylinder head can and the support means that, in shall provided in the cylinder head so as to support the base end portion of the rocker arm pivotably, said support means, swingable base end portion of the rocker arm A rocker shaft that supports the rocker shaft, a holder that supports the rocker shaft, and an axis line along one diameter line of the rocker shaft. And an adjusting screw that is screwed into the holder and is supported by the cylinder head such that the tip of the adjusting screw can be rotated around the axis while being prevented from moving in the axial direction. that it shall be the features a.

Further, in the invention according to claim 2 , in addition to the configuration of the invention according to claim 1 , the head cover is provided with an operation hole for performing an operation of changing a swing fulcrum of the support means, The lid is closed so as to be openable and closable by a lid member that is elastically engaged with the head cover.

According to the first aspect of the present invention, the support means for supporting the base end portion of the rocker arm is configured to be able to change the swing fulcrum during engine operation. The valve clearance and lift amount of the engine valve can be adjusted by changing the swing fulcrum , and the support means supports the rocker arm's base end so that it can swing, and is provided on the tip side of the rocker arm. Therefore, it is possible to avoid an increase in the weight on the movable side of the rocker arm and contribute to an increase in the limit rotational speed of the engine.

In particular, the supporting means has a rocker shaft that supports the rocker arm so that the base end portion of the rocker arm can swing, a holder that supports the rocker shaft, and an axis that extends along one diameter line of the rocker shaft and passes through the rocker shaft and the holder. And an adjustment screw screwed to the holder, and the tip of the adjustment screw is supported on the cylinder head so as to be able to rotate around the axis while being prevented from moving in the axial direction. The rocker arm rocking fulcrum can be changed by displacing the rocker arm rocking fulcrum by moving the holder holding the rocker shaft in the axial direction of the adjusting screw with a simple operation of rotating the adjusting screw from be able to.

According to the second aspect of the present invention, the operation hole necessary for operating the support means from the outside of the head cover can be closed with the lid member for easy attachment / detachment operation, and the weight is increased by providing the lid member. Can be avoided.

  Embodiments of the present invention will be described below based on the embodiments of the present invention shown in the accompanying drawings.

  1 to 4 show a first embodiment of the present invention. FIG. 1 is a longitudinal side view of a main part of an internal combustion engine, FIG. 2 is an enlarged view of a portion indicated by an arrow 2 in FIG. 1, and FIG. 3-3 is a sectional view, and FIG. 4 is a vertical perspective view of the support means.

  1, a cylinder head 5 of an internal combustion engine has a pair of intake valve ports 9 facing the ceiling surface of the combustion chamber 8 with the spark plug 7 facing the center portion, and a pair of exhausts facing the combustion chamber 8. An intake port 11 that opens to one side wall of the cylinder head 5 through a common connection to the valve ports 10 and the intake valve ports 9 and an opening to the other side wall of the cylinder head 5 through a common connection to both exhaust valve ports 10. Exhaust ports 12 are provided for each cylinder.

  The cylinder head 5 is provided with guide cylinders 14 for guiding the stems 13a of the intake valves 13 that can open and close the intake valve ports 9 in the opening / closing operation direction. Is driven to open and close.

  The cylinder head 5 is provided with a guide cylinder 16 for guiding the stem 15a of the exhaust valve 15 as an engine valve capable of opening and closing the exhaust valve port 10 in the opening / closing operation direction. A valve spring that urges the exhaust valve 15 in the valve closing direction between a spring receiving member 17 fixed to the upper end portion and a spring receiving member 18 that surrounds the guide cylinder 16 and contacts the upper surface of the cylinder head 5. 19 is contracted.

  The valve operating device that opens and closes the exhaust valves 15 includes a camshaft 22 provided with a cam 21 and a rocker arm 24 having a roller 23 that is a cam contact portion that contacts the cam 21. Is supported by the cylinder head 5 via the support means 25, and the tip of the rocker arm 24 is brought into contact with the upper ends of the stems 15a of the pair of exhaust valves 15.

  2 and 3 together, the rocker arm 24 includes a pair of side walls 24a, 24a parallel to each other along a plane perpendicular to the axis of the camshaft 22, and a pair of side walls on the side of the pair of exhaust valves 15. 24a, 24a, a pair of valve connecting arms 24c, 24c extending from the tip side connecting wall 24b to both sides, and between the side walls 24a on the opposite side of the exhaust valves 15. , And an intermediate connecting wall 24e connecting the lower portions of both side walls 24a at the intermediate portion between the distal end side and the base end side connecting walls 24b, 24d.

  The lower outer surfaces of the side walls 24a are opposed to the regulating walls 26, 26 provided on the cylinder head 5 on both sides of the rocker arm 24, and the valve connecting arms 24c are stems 15a of the pair of exhaust valves 15. It is contact | abutted at the upper end of. The roller 23 is disposed between the distal end side connecting wall 24b and the intermediate connecting wall 24e, and both ends of the roller 23 are rotatably supported by a support shaft 27 supported by the both side walls 24a through a needle bearing 28. .

  Referring also to FIG. 4, the support means 25 makes it possible to change the rocking fulcrum of the rocker arm 24 during engine operation in response to an operation from the outside of the head cover 6 coupled to the cylinder head 5. 5, and has a rocker shaft 29 that supports the rocker arm 24 in a swingable manner, a holder 30 that supports the rocker shaft 29, and an axis line along one diameter line of the rocker shaft 29. The locker shaft 29 and an adjustment screw 31 that passes through the holder 30 and is screwed to the holder 30 are provided.

  The rocker shaft 29 is disposed between the base end side connecting wall 24d and the intermediate connecting wall 24e of the rocker arm 24, and both side walls 24a, 24a of the rocker arm 24 can be rotated at both ends of the rocker shaft 29. Supported. The holder 30 integrally includes a cylindrical holding portion 30a that surrounds and holds the rocker shaft 29, and a cylindrical support portion 30b that is provided at right angles to the holding portion 30a and extends downward. The support portion 30b is slidably fitted into a bottomed support hole 32 provided in the cylinder head 5.

  The support portion 30b includes a first insertion hole 34 having one end opened on the inner surface of the holding portion 30a, a diameter larger than that of the first insertion hole 34, and coaxially connected to the other end of the first insertion hole 34 and the other end. Is formed coaxially with a screw hole 35 opened at the lower end of the support portion 30b, and a second insertion hole 36 having a smaller diameter than the first insertion hole 34 is provided at the upper end of the holding portion 30a. 34 and the same axis.

  The adjustment screw 31 has a first screw shaft portion 31a that is inserted into the second insertion hole 36 so as to be capable of relative movement in the axial direction so that one end protrudes above the upper end of the holder 30, and a first insertion hole 34. The shaft portion 31b is inserted into the first screw shaft portion 31a so as to be axially movable relative to the other end of the first screw shaft portion 31a and is coaxially connected to the other end of the first screw shaft portion 31a. A second screw shaft portion 31c coaxially connected to the other end and a support disk portion 31d coaxially connected to the other end of the second screw shaft portion 31c so as to face the lower end of the support portion 30b of the holder 30 are integrally provided. The support disk portion 31d is formed with a diameter larger than that of the second screw shaft portion 31c while being able to be inserted into the support hole 32, and can be rotated around the axis at the closed end of the support hole 32. As sliding contact, supported That.

  On the other hand, the rocker shaft 29 inserted and held in the holding portion 30a of the holder 30 is formed in a cylindrical shape. The rocker shaft 29 includes a first screw shaft portion 31a and a shaft portion of the adjusting screw 31. A pair of insertion holes 37, 37 arranged on one diameter line so as to allow 31b to pass therethrough are provided.

  That is, the adjusting screw 31 has an axis line along one diameter line of the rocker shaft 29 and penetrates the rocker shaft 29 and the holder 30 and is screwed into the screw hole 35 of the holder 30. The front end portion, that is, the support disk portion 31d is supported by the cylinder head 5 so as to be rotatable around the axis. Moreover, the rocker arm 24 connected to the holder 30 via the rocker shaft 29 is sandwiched from above and below by the exhaust valve 15 and the cam 21 that are urged in the valve closing direction by the valve spring 19. The support disk portion 31d does not move in the axial direction, and the lower outer surface of the side walls 24a of the rocker arm 24 is in close proximity to the restriction wall 26 of the cylinder head 5 so that it rotates about the axis of the adjusting screw 31. There is nothing. Therefore, the holder 30 moves up and down along the axis of the adjusting screw 31 in accordance with the rotation operation of the adjusting screw 31, and the axis of the rocker shaft 29 held by the holder 30, that is, the rocking fulcrum of the rocker arm 24 is adjusted. It will be displaced according to the vertical movement of the holder 30 according to the rotation of the screw 31.

  Incidentally, an engaging groove 38 for engaging a tool (not shown) to rotate the adjusting screw 31 is provided at the upper end of the adjusting screw 31, that is, one end of the first screw shaft portion 31a. A lock nut 39 for maintaining the relative position of the adjusting screw 31 and the holder 30 in the direction along the axis of the adjusting screw 31 is in contact with and engaged with the upper end of the holder 30 at the protruding portion of the one screw shaft portion 31a. In this way, they are screwed together.

  On the other hand, an operation hole 40 for enabling the adjustment screw 31 and the lock nut 39 to be rotated from the outside of the head cover 6 is provided in the head cover 6 above the support means 25. During the operation of the engine, when the tool is inserted into the operation hole 40 and the adjusting screw 31 and the lock nut 39 are rotated, oil splashes scattered in the space between the cylinder head 5 and the head cover 6 are exposed from the head cover 6 to the outside. In order to avoid scattering, it is desirable that a gap be formed as much as possible between the tool and the tool.

  Moreover, the operation hole 40 is closed by a lid member 41 so as to be opened and closed. The lid member 41 has an annular recess 42 on its outer periphery and is engaged by an elastic member. Is elastically engaged with the head cover 6 so as to engage with the peripheral edge of the operation hole 40.

  Next, the operation of the first embodiment will be described. The support means 25 that can change the rocking fulcrum of the rocker arm 24 during engine operation in accordance with the operation from the outside of the head cover 6 is based on the rocker arm 24. Since the end is provided in the cylinder head 5 so as to be swingably supported, the valve clearance of the exhaust valves 15 can be adjusted by changing the swing support point of the rocker arm 24 during engine operation. Thus, generally, the exhaust valve 15 is open even after the top dead center of the piston, and adjusting the valve clearance changes the valve lift and valve closing timing at the time of valve opening, thereby affecting the compression pressure. Therefore, by adjusting the lift amount of the intake valves 13 during engine operation in accordance with the compression pressure and adjusting the valve clearance of the exhaust valves 15, the control for suppressing the variation in the intake amount for each cylinder is made finer. It can be carried out.

  Moreover, the rocker arm 24 is integrally provided with valve connecting portions 24c that abut against the pair of exhaust valves 15, and the adjustment of the pair of exhaust valves 15 can be performed with a single adjustment, so that the number of adjustment steps can be reduced. Can be planned.

  The support means 25 supports the base end of the rocker arm 24 in a swingable manner, and is not provided at the distal end side of the rocker arm 24. Therefore, an increase in the weight on the movable side of the rocker arm 24 is avoided to limit the engine. This can contribute to an increase in rotational speed.

  The support means 25 has a rocker shaft 29 that supports the rocker arm 24 so as to be swingable, a holder 30 that supports the rocker shaft 29, and an axis that extends along one diameter line of the rocker shaft 29. An adjusting screw 31 that passes through the rocker shaft 29 and the holder 30 and is screwed to the holder 30 is provided, and the tip of the adjusting screw 31 is allowed to rotate around the axis while being prevented from moving in the axial direction. Thus, the holder 30 holding the rocker shaft 29 is displaced in the axial direction of the adjusting screw 31 by a simple operation of rotating the adjusting screw 31 from the outside of the head cover 6 to swing the rocker arm 24. The moving fulcrum can be changed, and the rocking fulcrum of the rocker arm 24 can be changed reliably. It is possible.

  Further, the head cover 6 is provided with an operation hole 40 for performing an operation for changing the swing fulcrum of the support means 25, and the operation hole 40 is closed by a lid member 41 that is elastically engaged with the head cover 6. Therefore, the operation hole 40 can be closed with the lid member 41 to facilitate the attachment / detachment operation, and an increase in weight due to the provision of the lid member 41 can be avoided.

  As a second embodiment of the present invention, as shown in FIG. 5, an operation hole 40 ′ provided in the head cover 6 to enable the adjustment screw 31 and the lock nut 39 to be rotated from the outside of the head cover 6. You may make it close so that opening and closing is possible with the cover member 42 screwed together by the head cover 6. FIG.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.

  For example, in the above embodiment, the exhaust valve 15 has been described as an engine valve, but the present invention can also be implemented in connection with an intake valve.

It is a principal part vertical side view of the internal combustion engine of 1st Example. FIG. 2 is an enlarged view of a portion indicated by an arrow 2 in FIG. 1. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. It is a vertical perspective view of a support means. It is a principal part vertical side view of the internal combustion engine of 2nd Example.

5 ... Cylinder head 6 ... Head cover 15 ... Exhaust valve 21 as engine valve ... Cam 22 ... Cam shaft 23 ... Roller 24 as cam contact part ... Rocker arm 25 ..Support means 29 ... Rocker shaft 30 ... Holder 31 ... Adjust screw 40 ... Operation hole 41 ... Lid member

Claims (2)

A base end portion of a rocker arm (24) having a cam contact portion (23) that comes into contact with a cam (21) provided on the camshaft (22) is rotatably supported by the cylinder head (5), and the rocker arm (24 ) a valve operating system for an internal combustion engine the tip is brought into contact with the engine valve (15) of the engine during operation in response to operation from the outside of the head cover (6) coupled to said cylinder head (5) The cylinder head (5) is configured such that the support means (25) that can change the rocking fulcrum of the rocker arm (24) supports the base end of the rocker arm (24) in a rocking manner. in shall provided,
The support means (25) includes a rocker shaft (29) that pivotably supports a base end portion of the rocker arm (24), a holder (30) that supports the rocker shaft (29), and the rocker shaft ( 29) an adjusting screw (31) having an axis along one diameter line and passing through the rocker shaft (29) and the holder (30) and screwed into the holder (30), A valve operating system for an internal combustion engine, characterized in that the tip of the adjusting screw (31) is supported on the cylinder head (5) so as to be able to turn around the axis while being prevented from moving in the axial direction. Place. The head cover (6) is provided with an operation hole (40) for performing an operation for changing the swing fulcrum of the support means (25), and the operation hole (40) is elastically applied to the head cover (6). 2. The valve operating device for an internal combustion engine according to claim 1, wherein the valve operating device is closed so as to be opened and closed by an engaging lid member (41).

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