JP2008255874A - Variable valve gear for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable valve gear equipped with a variable valve characteristic mechanism which enhances the workability of adjustment work of a clearance in a transmission path of valve driving force reaching an engine valve from a valve cam through the variable valve characteristic mechanism and cam follower. <P>SOLUTION: A variable valve characteristic mechanism C of a variable valve gear 20 is equipped with an adjustment mechanism A for preventing or suppressing the occurrence of a clearance in a transmission path of valve driving force of an intake cam 21a reaching an intake valve 7 from a cam 21a through a sub-cam 40 and rocker arm 24. The adjustment mechanism A includes a support shaft 50 which rockably supports the sub-cam 40 and which is provided to the holder 30 so as to be positionally adjustable, and an adjustment bolt 60 and adjustment screw 70 which are provided to the holder 30 and which move a position of a rocking center line Ls of the sub cam 40 in the direction opposite to each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention includes a valve characteristic variable mechanism that includes a holder driven by a control member and a sub cam that is swingably supported by the holder and driven by a valve cam. The present invention relates to a variable valve operating apparatus for an internal combustion engine in which a maximum lift amount of an engine valve is changed by a mechanism.

A variable valve operating device for an internal combustion engine is driven by a valve operating cam that is driven in synchronization with the engine rotational speed, a holder that is driven by a control member, and a swingable support that is supported by the holder. A variable valve characteristic mechanism including a swinging sub cam and a cam follower (for example, a rocker arm) that is driven by the sub cam to open and close the engine valve, and when the holder is driven by the control member, the sub cam and the cam follower It is known that the maximum lift amount of the engine valve is changed by changing the contact position of the engine valve. (For example, see Patent Document 1)
JP 2005-315182 A

In a variable valve operating apparatus having a variable valve characteristic mechanism, a valve operating cam opens and closes an engine valve via a variable valve characteristic mechanism and a cam follower (for example, a rocker arm), so that the valve operating apparatus opens and closes the engine valve only through the cam follower. Compared to a valve operating device that drives (hereinafter referred to as “invariable valve operating device”), many members are present in the transmission path of the valve driving force from the valve operating cam to the engine valve.
For this reason, in order to ensure the control accuracy of the changing maximum lift amount, a clearance (hereinafter referred to as “clearance”) is formed in the transmission path from the valve cam to the engine valve via the valve characteristic variable mechanism and the cam follower. ) Is important.
By the way, when the adjustment mechanism for adjusting the position of the member constituting the transmission path is provided in the rocker arm so that the clearance does not occur in the variable valve operating apparatus, it corresponds to the fact that the rocker arm is arranged in the vicinity of the engine valve. The adjustment mechanism is disposed near the bottom of the valve operating chamber in which the variable valve operating device is accommodated, and the variable valve characteristic mechanism is disposed between the valve operating cam and the rocker arm. However, since the work is performed while avoiding the valve characteristic variable mechanism at the back of the valve operating chamber, the workability is not good. Therefore, if an attempt is made to arrange the adjustment mechanism at a position where adjustment work can be easily performed on the rocker arm, the rocker arm will be enlarged, or the shape and arrangement of components of the variable valve characteristic mechanism will be restricted, and the variable valve characteristic mechanism will be enlarged. There is.
Further, if the adjusting member is provided on a member driven by the valve cam, such as a rocker arm, the valve system equivalent mass driven by the valve cam increases due to the adjusting member. The engine speed at which the engine is generated decreases, the frequency of occurrence of bounce increases, and the frequency of occurrence of noise due to the bounce may increase. In the variable valve operating apparatus, bounce is likely to occur because the valve system equivalent mass is larger than that of the invariable valve operating apparatus by the variable valve characteristic mechanism.

  The present invention has been made in view of such circumstances, and the invention according to claims 1 to 7 is a variable valve operating apparatus including a valve characteristic variable mechanism, wherein the valve characteristic variable mechanism and the cam follower are changed from the valve cam. An object of the present invention is to improve the workability of the clearance adjustment work in the transmission path of the valve driving force through the engine valve. The inventions of claims 2 and 3 further aim to prevent an increase in valve system equivalent mass due to the adjustment mechanism, and to suppress the bounce of the engine valve and the noise caused by the bounce, A further object of the present invention is to reduce the size of the support member that is moved by the adjustment mechanism in the radial direction centered on the oscillation center line.

According to the first aspect of the present invention, the valve drive cam driven in synchronization with the engine rotational speed, the holder driven by the control member, the swingable support supported by the holder and the drive of the valve drive cam. And a cam follower that is driven by the sub cam to open and close the engine valve, and the holder is driven by the control member, whereby the sub cam and the cam follower are provided. In the variable valve operating apparatus of the internal combustion engine in which the relative lift position of the engine valve is changed and the maximum lift amount of the engine valve is changed, the valve characteristic variable mechanism passes through the valve characteristic variable mechanism and the cam follower from the valve operating cam. An adjustment mechanism that prevents or suppresses the generation of clearance in the transmission path of the valve driving force of the valve drive cam leading to the engine valve; A variable valve device for an internal combustion engine having a first adjusting member and the second adjustment member to move the position of the swing center line of the sub cam in opposite directions in the holder.
According to a second aspect of the present invention, in the variable valve operating apparatus for the internal combustion engine according to the first aspect, the adjustment mechanism includes a support member that supports the sub cam in a swingable manner and is provided in the holder so that the position can be adjusted. The first adjustment member and the second adjustment member adjust the position of the support member relative to the holder by applying an adjustment force to the support member.
According to a third aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to the first or second aspect, the first adjustment member and the second adjustment member are provided in the holder.
According to a fourth aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to any one of the first to third aspects, the first adjustment member and the second adjustment member are on straight lines parallel to each other. The first adjustment direction and the second adjustment direction are moved to move the position of the swing center line, and the first adjustment direction and the second adjustment direction are the same direction.
According to a fifth aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to any one of the first to third aspects, the first adjusting member and the second adjusting member are respectively non-parallel straight lines. The first adjustment direction is inclined with respect to the second adjustment direction when viewed from the oscillation center line direction. It is what.
According to a sixth aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to the fifth aspect, the first adjustment direction is a direction approaching the second adjustment direction when viewed from the oscillation center line direction. It is.
According to a seventh aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to the sixth aspect, the first adjustment member is provided with a screw portion that is screwed into the holder and a shaft portion that abuts on the support member. And an adjustment bolt having a head engaged with the outer surface of the holder in the first adjustment direction and engaged with a tool for screwing the shaft portion in the first adjustment direction into the holder.

According to the first aspect of the present invention, the adjusting mechanism prevents or suppresses the generation of clearance in the transmission path of the valve driving force of the valve operating cam from the valve operating cam to the engine valve via the valve characteristic variable mechanism and the cam follower. However, since the position of the swing center line of the sub cam is adjusted, the sub cam driven by the valve cam is compared with the cam follower that is driven by the sub cam and opens and closes the engine valve. Because the sub cam is supported by the holder and the holder arrangement is unlikely to interfere with the adjustment operation of the position of the swing center line, the adjustment work by the adjustment mechanism becomes easy. Workability is improved. In addition, since the first and second adjustment members that move the swing center line in directions opposite to each other are provided, the position can be adjusted with high accuracy with a simple structure, and the control accuracy of the maximum lift amount is improved.
According to the second aspect of the present invention, since the support member constituting the adjustment mechanism supports the sub cam in a swingable manner and is provided on the holder, the valve system equivalent mass may be increased by the support member of the adjustment mechanism. Therefore, the engine rotational speed at which the engine valve bounces can be shifted to a higher speed side, so that the occurrence of bounces and the noise caused by the bounces are suppressed. Further, since the position of the support member that supports the sub cam so as to be swingable may be adjusted by the first and second adjustment members, the adjustment operation of the position of the swing center line is facilitated. Further, since the support member that supports the sub cam constitutes the adjustment mechanism, the number of parts is reduced.
According to the third aspect of the present invention, since the first and second adjustment members constituting the adjustment mechanism are provided in the holder, the valve system equivalent mass is not increased by the first and second adjustment members. Since the engine speed at which the engine valve bounces can be shifted to a higher speed side, the occurrence of bounces and the noise caused by the bounces are suppressed.
According to the fourth aspect, since the adjustment directions of the first and second adjustment members are parallel and in the same direction, the adjustment operation is facilitated.
According to the fifth aspect of the present invention, the degree of freedom of arrangement of the first and second adjustment members is increased, and the position of the oscillation center line is adjusted according to the arrangement of the components of the valve gear. Since the 1st, 2nd adjustment member can be arrange | positioned in the easy position, it contributes to the improvement of workability | operativity of adjustment work.
According to the sixth aspect, even when the first and second adjustment members are arranged close to each other, the tool used when adjusting one of the first and second adjustment members is the first tool. Since the interference with the other of the second adjusting members is prevented, the adjusting operation is facilitated while the first adjusting member and the second adjusting member are arranged in a compact manner.
According to the seventh aspect, since the first adjustment direction is a direction approaching the second adjustment direction, it is screwed in the first adjustment direction as compared with the case where the first and second adjustment directions are parallel to each other. In the adjustment bolt, the contact portion of the shaft portion with the support member can be brought closer to the head with the second adjustment member. As a result, while preventing interference between the tool engaged with the head and the second adjustment member, the portion to which the adjustment force by the adjustment bolt and the second adjustment member is applied can be brought close to the support member. The support member can be reduced in size in the radial direction with the center line as the center.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
1-9 is a figure explaining 1st Embodiment.
Referring to FIG. 1, the variable valve operating apparatus to which the present invention is applied is provided in an overhead camshaft type valve operating apparatus, and the valve operating apparatus is provided in an internal combustion engine E mounted on a vehicle. The multi-cylinder four-stroke internal combustion engine E includes a cylinder block 1 in which a plurality of cylinders 1 a are integrally formed, a cylinder head 2 coupled to the upper end portion of the cylinder block 1, and a head cover 3 coupled to the upper end portion of the cylinder head 2. The engine body is composed of

  In this embodiment, the vertical direction coincides with the direction of the cylinder axis Ly of the cylinder 1a, and the center line direction is a direction parallel to a swing center line Ls of a sub cam 40 described later (that is, a swing center line direction). Alternatively, it means a direction parallel to the rotation center line Lc of the cam 21a, which will be described later, the side view means viewing from the center line direction, and the plan view means viewing from the up and down direction.

A piston 4 connected to the crankshaft via a connecting rod is fitted to each cylinder 1a so as to be able to reciprocate. In the cylinder head 2, for each cylinder 1 a, an intake port 6 and a pair having a combustion chamber 5 facing the piston 4 in the cylinder axial direction (or vertical direction) and a pair of intake ports opening to the combustion chamber 5, respectively. An exhaust port having an exhaust port, an intake valve 7 (see also FIGS. 3 and 4) as a pair of engine valves for opening and closing the intake port, and an exhaust as a pair of engine valves for opening and closing the exhaust port A valve and a spark plug 9 disposed in the housing cylinder 8 and facing the combustion chamber 5 are provided.
The intake valve 7 and the exhaust valve for each combustion chamber 5 are driven to open and close by the valve operating device housed in the valve operating chamber 10 formed by the cylinder head 2 and the head cover 3.

  Then, the intake air passing through the intake passage formed by the intake device (not shown) of the internal combustion engine E is mixed with the fuel supplied from the air-fuel mixture forming device constituted by the fuel injection valve to form an air-fuel mixture. In the intake stroke, the intake valve 7 is sucked into the combustion chamber 5 through the intake port 6 when the valve is opened. The air-fuel mixture is compressed during the compression stroke in which the piston 4 rises, is ignited and burned by the spark plug 9 at the end of the compression stroke, and the piston 4 driven by the pressure of the combustion gas in the expansion stroke in which the piston 4 descends The crankshaft is driven to rotate. The combustion gas is discharged from the combustion chamber 5 as exhaust gas when the exhaust valve is opened in the exhaust stroke in which the piston 4 is lifted, passes through the exhaust port, and then passes through an exhaust passage formed by an exhaust device (not shown). And discharged outside the internal combustion engine E.

The valve operating device provided in the cylinder head 2 includes an intake side valve operating device that includes an intake cam shaft 21 provided with an intake cam 21a as a valve operating cam and opens and closes the intake valve 7, and an exhaust as a valve operating cam. An exhaust side valve device (not shown) that includes an exhaust cam shaft provided with a cam and drives the exhaust valve to open and close is configured. And in this embodiment, the said intake side valve operating apparatus is comprised from the variable valve operating apparatus 20 which can change the valve operating characteristic containing the maximum lift amount of the intake valve 7 according to the engine operating state of the internal combustion engine E. FIG. .
The exhaust side valve operating device is configured by a valve operating device whose valve operating characteristics are constant with respect to the engine operating state, but may be configured by a variable valve operating device having basically the same structure as the variable valve operating device 20. Good.

The intake camshaft 21 and the exhaust camshaft that are disposed across a central plane 11 that includes the cylinder axis Ly and that is parallel to the rotation centerline Lc of the intake camshaft 21 rotate in parallel to the rotation centerline of the crankshaft. Provided integrally with the cylinder head 2 so as to have a center line (respectively the rotation center line of the intake cam 21a and the exhaust cam, and the intake cam 21a is the rotation center line Lc as shown in FIG. 1). The cylinder head 2 is rotatably supported by a cam shaft holder 12 (see FIG. 2).
The intake camshaft 21 and the exhaust camshaft are rotationally driven at a rotational speed 1/2 that of the crankshaft by the power of the crankshaft transmitted through a valve train transmission mechanism having a timing chain.

Hereinafter, the variable valve gear 20 will be mainly described.
Referring to FIGS. 1 to 6, the variable valve gear 20 takes in the valve driving force of the cam 21 a in addition to the cam shaft 21 having the cam 21 a that is driven to rotate in synchronization with the engine rotation speed of the internal combustion engine E. A variable valve characteristic mechanism C that can transmit to the valve 7 and change the maximum lift amount of the intake valve 7; a control member 22 that drives the holder 30 of the variable valve characteristic mechanism C to change the maximum lift amount; A cam follower that opens and closes the intake valve 7 by being driven by a sub-cam 40 of a valve characteristic variable mechanism C and a biasing member 23 for a holder that is provided in the head 2 and generates a biasing force that presses the holder 30 against the control cam 22c of the control member 22. As a rocker arm 24. The control member 22 drives the holder 30 according to the engine operating state of the internal combustion engine E, and the relative position or the contact position between the sub cam 40 and the rocker arm 24 according to the position of the holder 30 that is displaced with respect to the cylinder head 2. Is changed, and the maximum lift amount and the opening / closing timing, which are the valve operating characteristics of the intake valve 7, are changed.

The variable valve characteristic mechanism C is displaceable to the cylinder head 2 around a holder center line Lh parallel to the rotation center line Lc. Here, the valve characteristic variable mechanism C is swingably supported and driven by the control force of the control member 22 to swing. Holder 30, a sub cam 40 that is supported by the holder 30 so as to be swingable about a swing center line Ls, and is driven by the cam 21 a to swing, and the holder 30 is provided to press the sub cam 40 against the cam 21 a. The cam biasing member 48 and the sub cam in the holder 30 for preventing or suppressing the occurrence of clearance in the transmission path of the valve driving force of the cam 21a from the cam 21a through the sub cam 40 and the rocker arm 24 to the intake valve 7 And an adjustment mechanism A for adjusting the position of the 40 swing center lines Ls.
Here, the holder center line Lh and the swing center line Ls are parallel to the rotation center line Lc of the cam 21a.

  The control member 22 is provided on an electric motor 22a as an actuator attached to the cylinder head 2 and a drive shaft 22b that is rotationally driven by the electric motor 22a via a speed reduction mechanism, and has a driving force for swinging or stopping the holder 30. And a control cam 22c as a drive unit that acts on the holder 30. The electric motor 22a is controlled by an electronic control unit to which a detection signal from an operation state detection means for detecting the engine operation state of the internal combustion engine E such as the engine rotation speed and the engine load is input, so that the holder 30 is in the engine operation state. The holder 30 is driven so as to occupy the swing position set according to the above.

  A holder 30 that is swingably supported by a camshaft holder 12 (see FIG. 2) adjacent in the center line direction and arranged for each cylinder 1a is disposed between the cam 21a and the intake valve 7 in the vertical direction, and It arrange | positions under the cam 21a. The holder 30 has a pair of support walls 31 and 32 that are separated in the direction of the center line, and each support wall 31 and 32 in a direction (hereinafter referred to as “orthogonal direction”) orthogonal to the center plane 11 (see FIG. 1). A pair of connecting walls 33, 34 for connecting the both ends of each of them, a pair of columnar holder fulcrum portions 35 provided on the support walls 31, 32 and pivotally supported by the camshaft holder 12, and control It has a roller 36 as an action portion that abuts on the cam 22c and acts on the cam 22c. The pair of support walls 31 and 32 and the pair of connecting walls 33 and 34 form an accommodation space 39 in which the sub cam 40, the rocker arm 24, and the roller 36 are accommodated.

  The sub cam 40 disposed above the rocker arm 24 abuts on the intake cam 21a and a cylindrical fulcrum portion 41 that is swingably supported by the eccentric shaft portion 53 of the support shaft 50 that defines the swing center line Ls. It has a roller 42 as a cam contact portion, a pair of drive cam portions 44 that respectively contact the pair of rocker arms 24, and an action portion 46 on which the urging force of the urging member 23 acts. The roller 42 is rotatably supported by a pair of holding portions 43 projecting radially outward from the fulcrum portion 41. Since the action portion 46 connects the pair of holding portions 43, the rigidity of the pair of holding portions 43 that receive the valve driving force from the cam 21a is increased.

  The urging member 48 held by the connecting wall 33 includes a pressing member 48a that abuts on the acting portion 46 so as to apply an urging force, and a spring 48b disposed between the pressing member 48a and the connecting wall 33. The The pressing member 48a is slidably fitted into a cylindrical guide tube 49 that is press-fitted into the connecting wall 33 and fixed. The guide tube 49 disposed inside the spring 48b functions as a spring guide that prevents the spring 48b from falling down.

  Each drive cam portion 44 disposed inside the pair of support walls 31 and 32 in the center line direction has a cam surface 45 with which the roller 24c of the rocker arm 24 abuts, and the valve of the cam 21a input from the roller 42 The driving force is output to the intake valve 7 via the rocker arm 24. The cam surface 45 swings the rocker arm 24 regardless of the swing of the sub cam 40, and the drive surface 45a that swings the rocker arm 24 when the sub cam 40 swings to open the intake valve 7. And a non-driving surface 45b that keeps the intake valve 7 closed. The non-driving surface 45b is composed of a cylindrical surface centered on the swing center line Ls.

  Each rocker arm 24 includes a fulcrum portion 24a that is pivotably supported by a pivot 25 serving as a swing support portion that also serves as a hydraulic lash adjuster, and a roller as a driven contact portion that contacts the cam surface 45 of the drive cam portion 44. 24c and a valve pressing portion 24b that presses the valve stem of the intake valve 7. The pair of pivots 25 are attached to support portions 37 that are provided in the connecting wall 34 so as to be separated from each other in the center line direction. Therefore, the rocker arm 24 is swingably supported by the holder 30 via the pivot 25.

  The urging member 23 is accommodated in a pressing member 23a that abuts against an action portion 38 provided between the support portions 37 in the connecting wall 34, and in the accommodating portion 14a that is integrally formed with the accommodating cylinder 8, and the accommodating portion 14a. It is comprised by the spring 23b arrange | positioned between the press members 23a and urging | biasing the press member 23a.

  Referring to FIGS. 7 and 8, the adjusting mechanism A provided in the holder 30 supports the sub cam 40 in a swingable manner and supports a support shaft 50 as a support member provided in the holder 30 so that the position can be adjusted, and a support shaft 50. An adjustment bolt 60 as a first adjustment member that adjusts the position of the support shaft 50 and the swing center line Ls with respect to the holder 30 by applying an adjustment force that moves the support shaft 50 by contacting the driven-side contact portion 54 A second adjusting member that adjusts the position of the support shaft 50 and the swing center line Ls with respect to the holder 30 by applying an adjustment force that moves the support shaft 50 by contacting the driven-side contact portion 55 of the support shaft 50. Have. The second adjusting member is operated by an adjusting screw 70 for applying an adjusting force for moving the support shaft 50 by contacting the driven-side contact portion 55, a washer 78 provided on the adjusting screw 70, and an engaging tool. It is comprised by the lock nut 79 as a loosening prevention member rotated. A washer 78 attached to the adjustment screw 70 and a lock nut 79 that is also an operation unit with which the tool engages constitute a fixing member that prevents a change in the position of the adjustment screw 70 due to torque applied to the support shaft 50 by the sub cam 40.

The adjusting bolt 60 and the adjusting screw 70 are attached to the support wall 31 so that the axes Lb and Ln thereof are parallel to each other. Then, the adjustment bolt 60 and the adjustment screw 70 move in the first adjustment direction D1 and the second adjustment direction D2, which are directions on the axis lines Lb and Ln as parallel straight lines, respectively. The position of the swing center line Ls is moved in opposite directions.
Here, the axis lines Lb and Ln and the adjustment directions D1 and D2 are parallel to each other in a side view.

  A support shaft 50 that can be moved relative to the holder 30 and is pivotally supported in this embodiment is inserted into the support holes 31a and 32a provided in the support walls 31 and 32. , 32 slidably and rotatably supported by a pair of columnar supported parts 51, 52 and the supported parts 51, 52, and the sub cam 40 is connected to the supported part 51. , 52 and a cylindrical eccentric shaft portion 53 as an eccentric portion that supports the sub cam 40 so as to be swingable so as to have a swing center line Ls that is parallel to the rotation center line La and decentered by a predetermined eccentricity e. An eccentric shaft integrated so as to rotate integrally.

In this embodiment, the support shaft 50 is divided in which a first member 50a in which the supported portion 51 and the eccentric shaft portion 53 are integrally formed and a second member 50b forming the supported portion 52 are integrated by a screw portion. It is a member having a structure. The support shaft 50 is attached to the holder 30 in a state where movement in the center line direction is restricted by an adjusting screw 70 that also serves as a positioning member for the support shaft 50 in the center line direction.
The supported portions 51 and 52 and the eccentric shaft portion 53 are provided with an oil passage 59c through which oil is guided from the oil passage 59a provided in the camshaft holder 12 through the holder fulcrum portion 35 and the oil passage 59b of the support wall 32. Then, the oil in the oil passage 59c is supplied to the sliding portion between the eccentric shaft portion 53 and the fulcrum portion 41 of the sub cam 40.

  The contact portion 54 contacts the drive side contact portion 64 of the adjustment bolt 60 in the first adjustment direction D1, and the contact portion 55 contacts the drive side contact portion 75 of the adjustment screw 70 in the second adjustment direction D2. Touch. Both contact portions 54 and 55 are flat surfaces including the rotation center line La. In this embodiment, both contact portions 54 and 55 are formed by recesses provided in the supported portion 51. It is comprised by the wall surface of the space 56 and 57 each accommodated. Further, the both abutting portions 64 and 75 are front end surfaces composed of spherical surfaces of the front end portions 61a and 71 of the adjustment bolt 60 and the adjustment screw 70, respectively.

The adjustment bolt 60 and the adjustment screw 70 provided on the support walls 31 and 32 are inserted into insertion holes 31b and 31d provided on the support walls 31 and 32 so as to be movable relative to the holder 30.
The adjustment bolt 60 includes a shaft portion 61 provided with a screw portion 61b that is screwed to the tip portion 61a and the screw portion 31c in the insertion hole 31b, and the adjustment bolt 60 by rotating the adjustment bolt 60 in the adjustment direction D1 and the counter-adjustment direction D3. It has a head 62 as an operation part with which a tool for moving the adjustment bolt 60 is engaged. The adjustment screw 70 includes a distal end portion 71, a screw portion 72 screwed into the screw portion 31e provided on the support wall 31, and the adjustment screw 70 by rotating the adjustment screw 70 in the adjustment direction D2 and the counter adjustment direction D4. And an operation unit 73 with which a tool to be moved is engaged. Therefore, the adjustment bolt 60 and the adjustment screw 70 are screw parts that are screwed into the holder 30 in the adjustment directions D1 and D2, respectively.

And the contact parts 54 and 64 and the contact parts 55 and 75 are arrange | positioned on both sides of rotation centerline La.
Further, the entire space 56, 57, a part of each of the adjustment bolt 60 and the adjustment screw 70, and thus the contact portions 54, 55, 64, 75 are disposed inside the support walls 31, 32.

  Referring to FIG. 1, the supported portion 51, the adjusting bolt 60, the adjusting screw 70, the washer 78, and the lock nut 79 are disposed above the head cover 3 and the mating surface 2a of the cylinder head 2 and swing in the vertical direction. The center line Ls or the support shaft 50 is disposed on the side opposite to the cam surface 45 and the rocker arm 24 of the sub cam 40 and above the swinging center line Ls or the support shaft 50. Therefore, the adjustment bolt 60 and the adjustment screw 70 are disposed above the rocker arm 24, the drive cam portion 44, and the urging member 48 and close to the cam 21a in the vertical direction, and overlap with the roller 42 in a side view. Be placed. Further, the adjusting bolt 60, the adjusting screw 70, their head 62, and the operating portion 73 are arranged on the opposite side of the center plane 11 with respect to the swing center line Ls in the orthogonal direction.

  Therefore, when the adjustment screw is provided in the rocker arm 24 arranged at the bottom of the valve operating chamber 10 near the intake valve 7 and arranged below the sub cam 40 in the accommodation space 39 formed by the holder 30. In comparison, since the adjustment bolt 60 and the adjustment screw 70 are near the uppermost portion of the holder 30, the adjustment operation of the position of the swing center line Ls is facilitated.

  7 and 8, in order to adjust the position of the swing center line Ls, first, the optimum adjustment bolt 60 is selected from a plurality of types of adjustment bolts 60 having different lengths of the shaft portion 61. The head 62 is inserted into the insertion hole 31b until it contacts the outer surface 31s of the support wall 31, and is screwed into the support wall 31 in the adjustment direction D1. At this time, depending on the position of the support shaft 50, the abutment portion 64 abuts on the abutment portion 54, the support shaft 50 rotates in one direction, and the position of the swing center line Ls is the rotation center line La. Is moved on a circle whose radius is the amount of eccentricity e, and moves in one direction.

  Next, the adjusting screw 70 that has been previously inserted into the insertion hole 31d for positioning the support shaft 50 is screwed into the support wall 31 in the adjusting direction D2. At this time, depending on the position of the support shaft 50, the contact portion 75 contacts the contact portion 55, and the support shaft 50 rotates in the other direction opposite to the one direction. The position moves around the rotation center line La on a circle whose radius is the eccentricity e and moves in the other direction. Then, the adjustment by the adjustment screw 70 is completed in a state where the contact portions 54 and 64 and the contact portions 55 and 75 are in contact with each other, and the adjustment screw is adjusted by the lock nut 79 screwed to the washer 78 and the screw portion 72. 70 is fixed, and the position adjustment of the swing center line Ls by the adjustment mechanism A is completed.

  According to this, as compared with the adjustment mechanism having the gear mechanism for rotating the support shaft 50, the fluctuation of the position of the oscillation center line Ls caused by the backlash in the gear mechanism is eliminated. The amount control accuracy is improved. In addition, since the position of the swing center line Ls is defined by the adjustment bolt 60, unlike the adjustment mechanism in which the position of the swing center line Ls is defined by the adjustment screw, a lock nut screwed to the adjustment screw When the screw is screwed into the adjusting screw, the adjusting screw does not rotate and the position of the swing center line Ls is not shifted.

Next, the operation of the variable valve gear 20 will be described.
Referring to FIG. 9, when the internal combustion engine E is operated in a high load region, for example, the holder 30 occupies an upper limit position where the maximum lift amount of the intake valve 7 becomes the maximum value. At this time, the control cam 22c comes into contact with the roller 36 at a position where the height of the cam crest is maximum in the rotation range. The sub cam 40 driven by the cam 21a drives the rocker arm 24 by the drive surface 45a of the drive cam portion 44, and the intake valve 7 opens at the maximum value. FIG. 9 shows the cam 21a, the sub cam 40, the rocker arm 24, and the intake valve 7 at this time by a two-dot chain line, the roller 42 contacts the base circle of the cam 21a, and the roller 24c contacts the non-driving surface 45b. The intake cam 21a, the sub cam 40, and the rocker arm 24 when they are in contact and the intake valve 7 is in a closed state are indicated by solid lines.

  When the internal combustion engine E shifts to a smaller load region, the holder 30 has a roller 36 whose height of the cam crest of the control cam 22c increases as the control cam 22c is driven by the electric motor 22a and rotates counterclockwise. By contacting the lower part, the holder rotates about the holder center line Lh in the clockwise direction. By this rotation of the holder 30, the swing center line Ls moves in the clockwise direction, and the roller 24c comes into contact with the drive cam portion 44 at a position moved from the drive surface 45a side to the non-drive surface 45b side. For this reason, when the rocker arm 24 is driven by the drive surface 45a, the maximum lift amount of the intake valve 7 is continuously reduced.

  As shown in FIG. 5, when the roller 36 comes into contact with the position where the cam crest height of the control cam 22c is minimized, the holder 30 is the lower limit position where the maximum lift amount of the intake valve 7 becomes the minimum value. Occupy. At this time, although the sub cam 40 is driven by the cam 21a and rotates in the clockwise direction, the roller 24c contacts only the non-drive surface 45b of the drive cam portion 44, so that the rocker arm 24 does not swing and the intake valve 7 maintains the valve closed state. In FIG. 5, the intake cam 21a and the sub cam 40 at this time are indicated by a two-dot chain line, and the intake cam 21a when the roller 42 is in contact with the base circle of the intake cam 21a and the intake valve 7 is in the closed state. The sub cam 40 and the rocker arm 24 are indicated by solid lines. When the minimum value is set to zero, for example, the intake valve 7 is in a resting state.

Next, operations and effects of the embodiment configured as described above will be described.
The variable valve characteristic mechanism C of the variable valve device 20 is an adjustment that prevents or suppresses the generation of clearance in the transmission path of the valve driving force of the cam 21a from the cam 21a to the intake valve 7 through the sub cam 40 and the rocker arm 24. Since the mechanism A has the adjusting bolt 60 and the adjusting screw 70 for moving the position of the swing center line Ls of the sub cam 40 in the holder 30 in opposite directions, the position of the swing center line Ls of the sub cam 40 is adjusted. Compared to the case where the adjusting mechanism is provided in the rocker arm 24 that opens and closes the intake valve 7 driven by the sub cam 40, the sub cam 40 driven by the cam 21a is disposed near the cam 21a, and the sub cam 40 is a holder. Since the arrangement of the holder 30 is supported by 30 and does not easily interfere with the adjustment operation of the position of the oscillation center line Ls, the adjustment operation by the adjustment mechanism A is easy. It is, the work is improved. In addition, since the adjusting bolt 60 and the adjusting screw 70 for moving the swing center line Ls in opposite directions are provided, the position can be adjusted with high accuracy with a simple structure, and the control accuracy of the maximum lift amount is improved. .

  The adjustment mechanism A includes a support shaft 50 that supports the sub cam 40 so as to be swingable and is capable of adjusting the position of the holder 30, and an adjustment bolt 60 and an adjustment screw 70 that are provided on the holder 30. The adjustment screw 70 adjusts the position of the support shaft 50 with respect to the holder 30 by applying an adjustment force to the support shaft 50, so that the support shaft 50, the adjustment bolt 60, and the adjustment screw 70 constituting the adjustment mechanism A are attached to the holder 30. Since the adjustment mechanism A does not increase the valve operating system equivalent mass, the engine rotation speed at which the bounce of the intake valve 7 is generated can be shifted to a higher rotation side. Generation of noise due to the bounce is suppressed. Further, since the position of the support shaft 50 that supports the sub cam 40 so as to be swingable may be adjusted by the adjusting bolt 60 and the adjusting screw 70, the adjustment work of the position of the swing center line Ls is facilitated. Furthermore, since the support shaft 50 that supports the sub cam 40 constitutes the adjustment mechanism A, the number of parts is reduced.

  The adjusting bolt 60 and the adjusting screw 70 are moved in the adjusting direction D1 and the adjusting direction D2 on the axes parallel to each other to move the position of the swing center line Ls, and the adjusting direction D1 and the adjusting direction D1 are the same direction. As a result, both adjustment directions D1 and D2 are parallel and in the same direction, so that the adjustment work is facilitated.

  Next, second and third embodiments of the present invention will be described with reference to FIGS. The second and third embodiments are different from the first embodiment in a part of the adjustment mechanism A, and the others basically have the same configuration. Therefore, description of the same part is omitted or simplified, and different points will be mainly described. In addition, about the member same as the member of 1st Embodiment, or the corresponding member, the same code | symbol was used as needed.

First, a second embodiment will be described with reference to FIG.
The adjustment mechanism A includes a support shaft 50, a second adjustment member including an adjustment screw 70, a washer 78, and a lock nut 79, and a first adjustment member. The first adjustment member is rotated by an adjustment screw 80 that applies an adjustment force for moving the support shaft 50 by abutting against the abutment portion 54, a washer 88 provided on the adjustment screw 80, and a tool engaged therewith. And a lock nut 89 as a loosening member to be moved. A washer 88 attached to the adjustment screw 80 and a lock nut 89 that is also an operation portion with which the tool engages constitute a fixing member that prevents a change in the position of the adjustment screw 80 due to torque applied to the support shaft 50 by the sub cam 40.
The adjustment screw 80 includes a distal end portion 81, a screw portion 82 that is screwed into the screw portion 31e in the insertion hole 31d provided in the support wall 31, and a first adjustment direction D1 and counter-adjustment by rotating the adjustment screw 80. And an operating portion 83 engaged with a tool for moving the adjusting screw 80 in the direction D4. Therefore, the adjustment screw 80 is a screw component that is screwed into the holder 30 in the adjustment direction D1.
The drive side abutting portion 84 is constituted by a tip surface formed of a spherical surface of the tip portion 81. Both adjusting screws 80 and 70 are attached to the support wall 31 so that their axis lines Lm and Ln are parallel to each other. Then, they move in the adjustment direction D1 and the second adjustment direction D2, which are directions on the axes Lm and Ln as straight lines parallel to each other, and the positions of the support shaft 50 and hence the oscillation center line Ls are moved in opposite directions. Let

In order to adjust the swing center line Ls, first, the adjustment screw 80 is inserted into the insertion hole and screwed into the support wall 31 in the adjustment direction D1. At this time, depending on the position of the support shaft 50, the contact portion 84 contacts the contact portion 54, the support shaft 50 rotates in one direction, and the position of the swing center line Ls is the rotation center line La. Is moved on a circle whose radius is the amount of eccentricity e, and moves in one direction.
Next, the adjusting screw 70 that has been previously inserted into the insertion hole 31d is screwed into the support wall 31 in the adjusting direction D2. At this time, depending on the position of the support shaft 50, the contact portion 75 contacts the contact portion 55, and the support shaft 50 rotates in the other direction opposite to the one direction. The position moves around the rotation center line La on a circle whose radius is the eccentricity e and moves in the other direction. Then, by adjusting the positions of the adjustment screws 80 and 70 in the adjustment directions D1 and D2, the adjustment screws 80 and 70 are used with the contact portions 54 and 84 and the contact portions 55 and 85 in contact with each other. After the adjustment is completed, the adjustment screws 80 and 70 are fixed by lock nuts 89 and 79 screwed to the washers 88 and 78 and the screw portions 82 and 72, respectively, and the position of the swing center line Ls by the adjustment mechanism A Adjustment is complete.

According to the second embodiment, the same operations and effects as the first embodiment are exhibited, and the following operations and effects are exhibited.
That is, when adjusting the position of the swing center line Ls, the adjusting screws 80 and 70 are attached to the support wall 31 by moving the adjusting screws 80 and 70 in the adjusting directions D1 and D2 and the counter-adjusting directions D3 and D4. In this state, the position of the oscillation center line Ls can be adjusted by continuously moving.

Next, a third embodiment of the present invention will be described with reference to FIG.
The adjustment bolt 60 and the adjustment screw 70 are attached to the support wall 31 so that the axes Lb and Ln thereof are not parallel. Then, the adjustment bolt 60 and the adjustment screw 70 move in the first adjustment direction D1 and the second adjustment direction D2, which are directions on the axis lines Lb and Ln as non-parallel straight lines, respectively, and the positions of the support shafts 50 are respectively detected. Therefore, the position of the swing center line Ls is moved in the opposite directions.

Furthermore, in the side view, the adjustment direction D1 is a direction that approaches the adjustment direction D2, or is inclined so as to approach the adjustment direction D2. Here, “approaching” means a distance (that is, the straight line that intersects one of the adjustment directions D1 and D2 perpendicularly to one (for example, the adjustment direction D1) intersects the other (for example, the adjustment direction D2) (that is, the straight line) This means that the distance between the intersection with the adjustment direction D1 and the intersection between the straight line and the adjustment direction D2) gradually decreases in the adjustment direction D1 or the adjustment direction D2. In addition, when the adjustment direction D1 and the adjustment direction D2 are orthogonal to each other in a side view, the case where the adjustment direction D1 is a direction approaching the adjustment direction D2 and a case where the adjustment direction D1 is inclined are included.
The first outer surface 31s1 of the support wall 31 with which the insertion hole 31b is opened and the head 62 of the adjustment bolt 60 abuts in the adjustment direction D1 and the second outer surface 31s2 with the insertion hole 31d open are 180 in side view. An angle θ of less than 0 ° is formed, and the outer surface 31s1 is inclined with respect to the outer surface 31s2.

Both contact portions 54 and 55 are curved surfaces on a cylindrical surface whose shape in a side view is a circle having a diameter larger than the diameter of the eccentric shaft portion 53. In this embodiment, the contact portions 54 and 55 are provided on the supported portion 51. It is formed by the wall surface of one space 91 that is formed by the formed recess and accommodates both the abutting portions 64 and 75 respectively. As shown in FIG. 11, both contact portions 54 and 55 are located farther from the swing center line Ls than the outer peripheral surface of the eccentric shaft portion 53. Further, both abutting portions 64 and 75 are front end surfaces composed of flat surfaces of the front end portions 61a and 71 of the adjusting bolt 60 and the adjusting screw 70, respectively.
The adjustment of the swing center line Ls is performed in the same manner as in the first embodiment.

According to the third embodiment, the same operations and effects as the first embodiment are exhibited, and the following operations and effects are also achieved.
The adjustment bolt 60 and the adjustment screw 70 move in the adjustment direction D1 and the adjustment direction D2 on the non-parallel straight lines Lb and Ln, respectively, to move the position of the swing center line Ls, and in the side view, the adjustment direction Since D1 is inclined with respect to the adjustment direction D2, the degree of freedom of arrangement of the adjustment bolt 60 and the adjustment screw 70 is increased, and according to the arrangement of the components of the valve gear, the oscillation center line Ls is increased. Since the adjustment bolt 60 and the adjustment screw 70 can be arranged at a position where the position adjustment work is easy to perform, it contributes to improvement in workability of the adjustment work.

  Since the adjustment direction D1 is a direction approaching the adjustment direction D2, it is used to adjust one of the adjustment bolt 60 and the adjustment screw 70 even when the adjustment bolt 60 and the adjustment screw 70 are arranged close to each other. Tool is prevented from interfering with the other of the adjusting bolt 60 and the adjusting screw 70, and further, interference between tools engaging with the head 62 and the lock nut 79 is prevented. Adjustment work is facilitated while the screw 70 is arranged compactly.

  The adjustment bolt 60 is provided with a threaded portion 61b that is screwed into the support wall 31, and a shaft portion 61 that contacts the supported portion 51 at the contact portion 64, and the shaft portion 61 on the support wall 31 in the first adjustment direction D1. A head 62 that engages with the outer surface 31s1 of the support wall 31 in the first adjustment direction D1 is engaged with the screwing tool, and the adjustment screw 70 is a tip that contacts the supported portion 51 at the contact portion 75. The first adjustment direction D1 is a direction approaching the second adjustment direction D2. Further, the first adjustment direction D1 is loosened by a lock nut 79 having a portion 71 and a screw portion 72 screwed to the support wall 31 and operated by a tool. Thereby, compared with the case where 1st, 2nd adjustment direction D1, D2 is mutually parallel, in adjustment bolt 60 screwed in 1st adjustment direction D1, contact part 64 is adjusted to head 62. In the adjustment screw 70 screwed in the first adjustment direction D <b> 2, the contact portion 75 can be brought closer to the lock nut 79 with the adjustment bolt 60. As a result, while preventing interference between the tool engaged with the head 62 and the adjusting screw 70 or the lock nut 79, or while preventing interference between the tool engaged with the lock nut 79 and the head 62, The contact portion 54 is a portion to which adjustment force is applied by the adjustment bolt 60 and the adjustment screw 70 in the supported portion 51 of the support member 50 while preventing interference between the tools engaged with the head 62 and the lock nut 79, respectively. , 55 can be brought close to each other, so that the supported portion 51 can be reduced in size in the radial direction around the oscillation center line Ls.

  Both the contact portions 54 and 55 are located farther from the swing center line Ls than the outer peripheral surface of the eccentric shaft portion 53, so that the adjustment bolt 60 and the adjustment screw 70 by the torque applied to the support shaft 50 by the sub cam 40 are adjusted. Since the fluctuation of the position is prevented or suppressed, the fluctuation of the position of the adjusted swing center line Ls is prevented or suppressed, which contributes to the improvement of the control accuracy of the maximum lift amount.

  Both contact portions 54 and 55 are curved surfaces on a cylindrical surface whose shape in a side view is a circle having a diameter larger than the diameter of the eccentric shaft portion 53, so that both contact portions 54 and 55 are flat. Compared with the case where both contact portions 64 and 75 are curved surfaces, the contact surface pressure at both contact portions 54 and 64 and both contact portions 55 and 75 can be reduced and adjusted. The durability of the mechanism A is improved.

Hereinafter, an embodiment in which a part of the configuration of the above-described embodiment is changed will be described with respect to the changed configuration.
Both axis lines Lb, Ln, both axis lines Lm, Ln, and both adjustment directions D1, D2 are not parallel to each other, but both axis lines Lb, Ln, both axis lines Lm, Ln, and both adjustment directions D1, D2 are respectively The adjustment bolt 60 or the adjustment screw 80 and the adjustment screw 70 may be arranged so as to be parallel to each other.
The first and second adjustment members may be provided so as to be distributed between the pair of support walls 31 and 32.
The internal combustion engine may be a single cylinder internal combustion engine. Although the internal combustion engine is used for a vehicle in the embodiment, it may be used for a ship propulsion device such as an outboard motor having a crankshaft oriented in the vertical direction.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a main part on a plane orthogonal to a rotation center line of a crankshaft of an internal combustion engine including a variable valve apparatus according to a first embodiment of the present invention. It is a figure of the principal part by the 2 arrow view of FIG. It is a perspective view of the variable valve apparatus of FIG. It is a perspective view from the direction different from FIG. 3 of the variable valve apparatus of FIG. It is sectional drawing of the variable valve apparatus of FIG. 1 corresponded to the 5-5 line arrow of FIG. It is sectional drawing of the variable valve apparatus of FIG. 1 corresponded to the 6-6 line arrow of FIG. FIG. 7 is an essential part cross-sectional view taken along line 7-7 in FIG. 1. FIG. 8 is an enlarged cross-sectional view of a main part taken along line 8-8 in FIG. 7. It is a figure corresponding to FIG. 5 when the holder of a variable valve apparatus occupies the position different from FIG. FIG. 9 shows a second embodiment of the present invention and corresponds to FIG. FIG. 9 shows a third embodiment of the present invention and corresponds to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Cylinder head, 7 ... Intake valve, 20 ... Variable valve apparatus, 21a ... Cam, 22 ... Control member, 24 ... Rocker arm, 30 ... Holder, 31, 32 ... Support wall, 33, 34 ... Connection wall, 40 ... Sub cam, 45 ... cam surface, 50 ... support shaft, 51,52 ... supported portion, 53 ... eccentric shaft portion, 54,55 ... contact portion, 60 ... adjustment bolt, 64 ... contact portion, 70, 80 ... adjustment Screw, 75, 85 ... contact part,
E: internal combustion engine, C: variable valve characteristic mechanism, Ls: swing center line, La: rotation center line, A: adjustment mechanism, D1, D2: adjustment direction.

Claims (7)

A valve cam that is driven in synchronism with the engine speed;
A variable valve characteristic mechanism comprising a holder driven by a control member, and a sub cam that is swingably supported by the holder and driven by the valve cam;
A cam follower driven by the sub cam to open and close the engine valve;
In the variable valve operating apparatus for an internal combustion engine in which the relative position between the sub cam and the cam follower is changed by changing the maximum lift amount of the engine valve by driving the holder from the control member.
The valve characteristic variable mechanism is an adjustment that prevents or suppresses generation of a clearance in the transmission path of the valve driving force of the valve cam from the valve cam to the engine valve via the valve characteristic variable mechanism and the cam follower. A variable valve for an internal combustion engine comprising a first adjustment member and a second adjustment member that move a position of a swing center line of the sub cam in the holder in opposite directions to each other. apparatus.   The adjustment mechanism includes a support member that swingably supports the sub cam and is provided on the holder so that the position of the sub cam can be adjusted. The first adjustment member and the second adjustment member apply an adjustment force to the support member. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the position of the support member with respect to the holder is adjusted by adding.   The variable valve operating apparatus for an internal combustion engine according to claim 1 or 2, wherein the first adjusting member and the second adjusting member are provided in the holder.   The first adjustment member and the second adjustment member move in a first adjustment direction and a second adjustment direction on straight lines parallel to each other to move the position of the swing center line, and the first adjustment direction The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the second adjustment direction is the same direction.   The first adjustment member and the second adjustment member are moved in a first adjustment direction and a second adjustment direction on straight lines that are not parallel to each other to move the position of the swing center line, and the swing center line 4. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the first adjustment direction is inclined with respect to the second adjustment direction as viewed from the direction. 5.   6. The variable valve operating apparatus for an internal combustion engine according to claim 5, wherein the first adjustment direction is a direction approaching the second adjustment direction when viewed from the swing center line direction.   The first adjustment member is provided with a screw portion that is screwed into the holder, and a shaft portion that contacts the support member, and a tool for screwing the shaft portion into the holder in the first adjustment direction is engaged with the first adjustment member. The variable valve operating apparatus for an internal combustion engine according to claim 6, further comprising an adjustment bolt having a head abutting on an outer surface of the holder in the first adjustment direction.

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