JPH11247635A - Variable valve system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow the variable operation of a lift amount only on the base circle of a cam by a simple structure. SOLUTION: A variable mechanism varying the rocking fulcrum of a high speed rocker arm 20 comprises a moving strut which is attached on a cylinder head 40 so that the rocking of the high speed rocker arm 20 can be supported and can be moved to the cylinder head 40 by releasing oil applied to one end side of the cylinder head 40, and also is provided with a timing control mechanism which allows the movement of the moving strut only during low and high speed rocker arms 21, 22, 20 are brought into sliding contact with the base circles of the low and high speed cams 12, 13, 14 by synchronizing opening/ closing of control oil passages 16, 17 for releasing oil respectively formed in the camshaft 11 with the rotation of the camshaft 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve apparatus for varying the lift of intake and exhaust valves that are opened and closed in synchronization with a crankshaft of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as this kind of variable valve train,
Japanese Patent Application Laid-Open No. 6-280523 is known. This device includes a cam that is rotated in synchronization with a crankshaft of an internal combustion engine, a rocker arm that is swung by the rotation of the cam to lift a valve, and a variable mechanism that makes a rocking fulcrum of the rocker arm variable. And the lift amount of the valve can be adjusted.

In this conventional device, the variable mechanism defines a virtual swing fulcrum of the rocker arm and is composed of a large number of support links for supporting the rocker arm.
The lift amount of the valve is adjusted by making the rocking fulcrum of the rocker arm variable by the movement of the large number of support links.

[0004]

However, according to the above-mentioned conventional apparatus, a large number of supporting links are required to make the rocking arm of the rocker arm variable, so that the structure is complicated and the number of parts is large. It is disadvantageous in terms of cost and space. In addition, since the rocking fulcrum of the rocker arm is virtually defined by a large number of support links, there is a possibility that the play existing at the connecting portion of each link may move the rocking fulcrum of the rocker arm, and as a result, the valve The lift amount was not stable, and there was a risk of subtle changes.

In order to solve these problems, the applicant of the present invention has made intensive efforts, and in Japanese Patent Application No. 8-295421, a novel variable valve apparatus for changing the rocking fulcrum of the rocker arm with a simpler structure. Suggested. In this variable valve operating device, the variable mechanism is attached to the cylinder head at one end so as to be able to support the rocking of the rocker arm, and one or more of the variable mechanisms are constituted by a plurality of columns that are movable to the cylinder head. I have. The support column cannot move with respect to the cylinder head by holding the hydraulic pressure applied to the other end side, and can support the rocker arm swinging, and can move with respect to the cylinder head by releasing the hydraulic pressure As a result, the rocker arm cannot be swung. Thereby, the rocking fulcrum of the rocker arm can be changed with a simple structure by holding or releasing the hydraulic pressure acting on the other end of each pillar, and appropriately selecting the pillar that supports the rocker arm swing. .

However, in the above-mentioned variable valve operating device, the holding and release of the hydraulic pressure acting on the column of the variable mechanism is performed arbitrarily even during the valve lift. If the valve becomes a rocking fulcrum of the rocker arm and the valve is in a low lift state and lifted, and the other end of another pillar that was movable up to that time is held immobile due to hydraulic pressure, the rocker arm will be moved from that point on. The swing fulcrum is switched to another support, and the valve lift (high lift) is continued. Therefore, not only the lift amount is not stable,
The overall dimensions of the valve train may be inconsistent and the cam may return to the base circle and the valve may be seated and the tapping sound may be generated or damaged. For example, as described in Japanese Patent Application Laid-Open No. 7-49012, one solenoid valve per valve controls the holding and release of the hydraulic pressure acting on the other end of the column, and
It is possible to solve this problem by controlling the solenoid valve not to operate during the lift and prohibiting the variable lift operation. However, this variable valve apparatus is applied to a valve apparatus for a one-cylinder four-valve internal combustion engine. In this case, since one solenoid valve is required for each valve, the number of parts increases, the cost increases, and the control becomes complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a variable valve apparatus in which a variable operation of a lift amount is permitted only on a base circle of a cam with a simple configuration.

[0008]

Means for Solving the Problems The technical means according to the first aspect of the present invention, which has been taken to solve the above problems, is provided rotatably on a cylinder head of an internal combustion engine, and rotates in synchronization with a crankshaft. A rocker arm that is swung by sliding contact with a cam integrally provided on the camshaft according to rotation of the camshaft to lift and open and close an intake / exhaust valve, and the rocker arm A variable mechanism for varying the swing fulcrum of the internal combustion engine, wherein the lift amount or opening / closing timing of the intake / exhaust valve is varied. A plurality of struts which are attached to the cylinder head so as to support the cylinder head, and at least one of which is movable to the cylinder head by releasing a hydraulic pressure applied to one end thereof. And the opening and closing of a control oil passage for releasing the oil pressure formed in the camshaft is synchronized with the rotation of the camshaft, so that the rocker arm moves the support post by the base circle of the cam. And a timing control mechanism that allows only during the sliding contact.

According to the above-mentioned means, the movement of the column of the variable mechanism is permitted only while the rocker arm is in sliding contact with the base circle of the cam by the timing control mechanism. It is prohibited and a stable lift can be obtained.

In order to solve the above-mentioned problems, the technical means of the invention according to claim 2 is provided so as to be rotatable on a cylinder head of an internal combustion engine, to be rotated in synchronization with a crankshaft and to rotate at a low speed. A camshaft having a cam for high speed and a cam for high speed having a nose portion larger than the nose portion of the cam for low speed, and the first swing fulcrum is slid by the low speed cam in accordance with the rotation of the camshaft. A low-speed rocker arm that is swung to lift and open and close the intake / exhaust valve, and is swung about a second swing fulcrum by sliding contact with the high-speed cam in response to the rotation of the camshaft. A high-speed rocker arm that can be opened and closed by lifting an intake / exhaust valve through the use rocker arm, and a variable mechanism that makes a second swing fulcrum of the high-speed rocker arm variable; In a variable valve operating apparatus for an internal combustion engine having a variable lift amount or opening / closing timing, the variable mechanism is attached to the cylinder head so as to support swinging of the high-speed rocker arm, and a hydraulic pressure applied to one end of the cylinder head. Is released from the cylinder head, the opening and closing of the control oil passage for releasing the hydraulic pressure formed in the camshaft is synchronized with the rotation of the camshaft. In addition, a timing control mechanism is provided which permits the movement of the moving column only while the low-speed and high-speed rocker arms are in sliding contact with the base circles of the low-speed and high-speed cams.

[0011] In this means, a pressure chamber formed at one end of the moving support in the hole by slidably fitting the moving support in a sliding hole formed in the cylinder head; A one-way valve that is interposed between the pressure chamber and an oil passage formed in the cylinder head and allows only oil flow from the oil passage to the pressure chamber; and the timing control mechanism includes: A release position attached to the cylinder head and pushing the one-way valve at one end to open the valve, and a return position where one end is separated from the one-way valve to maintain the one-way valve closed. The other end has a plunger movable by supplying and discharging hydraulic pressure through the control oil passage, and the control oil passage has at least the low-speed and high-speed rocker arms at the low-speed and high-speed rocker arms. For each cam It is opened only during the contact circle and sliding is desired.

According to the second aspect of the present invention, when the movable support of the variable mechanism is moved, the low-speed and high-speed rocker arms are in sliding contact with the base circles of the low-speed and high-speed cams by the timing control mechanism. Since only the lift is permitted, the variable lift amount operation during the lift is prohibited, and a stable lift amount can be obtained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a variable valve train for an internal combustion engine according to the present invention is applied to an intake valve 30 will be described below with reference to the drawings.

In FIG. 1 and FIG. 2, the variable valve operating device comprises:
It is rotatably disposed on a cylinder head 40 of the internal combustion engine, is rotated in synchronization with a crankshaft (not shown), and is lower than a pair of low speed cams 12 and 13 and a nose portion of the low speed cams 12 and 13. A camshaft 11 having a high-speed cam 14 having a large nose portion, and a cylinder which is swung about a first swing supporting point A by sliding contact with the low-speed cams 12 and 13 in accordance with the rotation of the camshaft 11. Intake valve 3 for opening and closing intake hole 36a formed in head 2
In response to the rotation of the camshaft 11, the low-speed rocker arms 21, 22 that lift the “0” against the valve spring 34 and the high-speed cam 14 are slid around the second fulcrum B in accordance with the rotation of the camshaft 11. Rocker arm for low speed 21, 2
A high-speed rocker arm 20 that lifts the intake valve 30 through the valve 2 and a variable mechanism that makes the second swing fulcrum B of the high-speed rocker arm 20 variable.

A pair of intake valves 30, which open and close intake holes 36a of an intake passage 36 formed in the cylinder head 40, have their shaft portions 31 slidably supported by the cylinder head 40 via guides 35. The intake hole 36a is always urged to the side that closes the intake hole 36a by a valve spring 34 interposed between a retainer provided in a concave portion formed in 40 and a retainer 32 attached to a tip end of a shaft portion 31 by a cotter 33.

The low-speed rocker arms 21 and 22 are oscillating ends (one end in the longitudinal direction at the left end in FIG. 1) on a pair of intake valves 30 (only one is shown).
Are arranged so as to be located on the shaft portion 31 of the intake valve 30, and a spherical projection 23 a contacting the tip of the shaft portion 32 of the intake valve 3 is provided on one end side of the swing ends 21 b and 22 b. Adjustment screws 23 are provided. Also,
A base end opposite to the end on the side of the intake valve 30 (the other end in the longitudinal direction, which is the right end in FIG. 1) is fixed to be immovably fitted into holes 41 and 42 formed in the cylinder head 40. Hemispherical concave portions 21c, 22c into which the hemispherical convex heads 50a, 51a of the columns 50, 51 are respectively slidably fitted are provided. The recesses 21 c and 22 c are located on the same straight line parallel to the camshaft 11. The swinging ends 21b and 22b of the low-speed rocker arms 21 and 22 are
It is connected in the axial direction of the camshaft 11 and is a bifurcated unitary body. In addition, the rocker arm 21 for low speed,
The cam followers 21a, 22a slidingly contacting the low-speed cams 12, 13 provided on the camshaft 11 so as to be spaced apart in the axial direction between the swinging ends 21b, 22b and the base end of the camshaft 11.
Are provided respectively.

In the high-speed rocker arm 20, the swinging end 20b on the intake valve 30 side is connected to the forked portion of the low-speed rocker arms 21 and 22 by the swinging ends 21b and 22b of the low-speed rocker arms 21 and 22. It is arrange | positioned so that it may contact on a connection part. Further, a hemispherical head 62 on one end side of a moving column 62 described later is provided at a base end opposite to the intake valve 30 side.
A semi-spherical concave portion 20c into which b is slidably fitted is provided. The recess 20c is provided with the recesses 21c and 22c.
At the same time, they are located on the same straight line parallel to the camshaft 11. The rocking end 20 of the high-speed rocker arm 20
Between b and the base end, a cam follower 20a is provided on the camshaft 11 for sliding contact with the high-speed cam 14 provided between the pair of low-speed cams 12, 13.

The variable mechanism is mainly composed of a moving column 62 and a hydraulic lifter 60 that constitute a second swinging fulcrum B.

As shown in FIG. 1, the moving support 62 is
The other end is supported in a hole 43 formed in the cylinder head 40 via a hydraulic lifter 60 so as to be movable in a direction orthogonal to the longitudinal direction of the high-speed rocker arm 20 (vertical direction shown in FIG. 1). The movable support 62 includes fixed supports 50, 5, and 5.
1 are located on the same straight line parallel to the camshaft 11.

As shown in FIG. 2, the hydraulic lifter 60 has a body 61 fitted in the hole 43 and movably supporting the movable support 62 in the inner hole 61a.
The body 61 is axially immovably held by a sleeve 63 screwed into the inner periphery of the opening of the hole 43 in a state where one end thereof is in contact with the bottom of the hole 43. Body 61
Is a pressure chamber 6 between the inner hole 61a and the other end of the moving support 62.
9 is formed, and a reservoir chamber R is formed between an annular groove formed on the outer periphery thereof and the hole 43. A passage 61b for communicating the pressure chamber 69 with the reservoir chamber R is formed in the body 61, and a check ball 67 capable of opening and closing the reservoir chamber R side opening end 61c of the passage 61b is provided in the passage 61b. Have been. In the pressure chamber 69,
It is filled with an amount of pressure oil that fills the pressure chamber 69,
This pressure oil is supplied to the reservoir chamber R and the pressure chamber 6 through the passage 61b.
Navigating between 9 The check ball 67 is opened by a spring 68 having one end locked to a retainer 65 fixed to the body 61.
1c is urged to close by contact with the body 61. Accordingly, the communication between the reservoir chamber R and the pressure chamber 69 is always closed by the check ball 67, and is opened by moving the check ball 67 against the urging force of the spring 68. The pressure oil filled in the pressure chamber 69 moves a pressure against the load applied from the high-speed rocker arm 20 to the moving support 62 in a state where the communication between the pressure chamber 69 and the reservoir chamber R is closed by the check ball 67. Act on the support 62. A spring 6 is provided between one end of the moving support 62 and the body 61.
4 is provided, and the movable support 62 is
By the urging force of No. 4, the head 62b is constantly urged in the direction in which the head 62b is inserted into the recess 20c (upward direction in FIG. 1). FIG.
Reference numeral 66 denotes a discharge hole formed in the cylinder head 40 so as to always communicate with the reservoir chamber R.

A stepped hole 44 is formed in the cylinder head 40 so as to be orthogonal to the hole 43 and open at one end on the small diameter portion 45 side to the reservoir chamber R. In the hole 44, a pin 71 which can move the check ball 67 against the spring 67 through the small diameter portion 45 and the reservoir chamber R at one end thereof and the other end of the pin 71 abut the bottom 74. A hydraulic plunger 70 having a cylindrical piston 72 disposed movably in a liquid-tight manner in the hole 44 is fitted. A plug 76 is press-fitted and fixed to the open end of the hole 44, whereby a hydraulic chamber 77 is formed in the hole 44 between the hydraulic plunger 70 and the plug 76. The hydraulic chamber 77 communicates with an oil pump 80 as a hydraulic pressure source via a passage 48 formed in the cylinder head 40, control oil passages 16 and 17 formed in the camshaft 11, a switching valve 81, and the like. A spring 73 is stretched between the other end of the pin 71 and the step of the hole 44, whereby the hydraulic plunger 70 is constantly biased toward the plug 76. When the hydraulic pressure from the oil pump 80 is not applied to the hydraulic chamber 77, the hydraulic plunger 70 is urged to the right by a spring 73 as shown in FIG.
2 comes into contact with a snap ring 75 fitted on the inner surface of the hole 44, and the tip of the pin 71 is separated from the check ball 67. When the hydraulic pressure from the oil pump 80 is applied to the hydraulic chamber 77, the hydraulic plunger 70 moves leftward in the drawing against the spring 73, and the pin portion 71 moves the check ball 67 against the spring 68. Then, the pressure chamber 69 and the reservoir chamber R communicate with each other.

As shown in FIGS. 2 and 3, the other end of the passage 48 having one end communicating with the hydraulic chamber 77 is connected to the camshaft 11.
The journal portion 15 is rotatably supported by a groove passage 47 formed in a circumferential direction on a bearing surface of a bearing portion 46 of the cylinder head 40. A cover 52 having a bearing surface for rotatably supporting the journal 15 is fixed to the bearing 46 by bolts 53 and 54.

Control oil passage 1 formed in camshaft 11
The axial passage 16 is formed in the axial center of the camshaft 11 in the axial direction, and has one end communicating with the switching valve 81.
The other end of the shaft passage 16 is communicated with an outside opening of the shaft passage 16, and the shaft passage 16 includes a radial passage 17 that can communicate with the groove passage 47 and the axial passage 16. As shown in FIG. 4, the intake valve 30 using the low speed cams 12, 13 or the high speed cam 14 is provided.
From the point at which the camshaft 11 has rotated by a predetermined angle α from the rotation angle (C) at the time of the maximum lift,
3 or a rotation angle (B) point that is a predetermined angle β before the angle at which the intake valve 30 starts to be lifted by the high-speed cam 14 (the base circle portions of the low-speed and high-speed cams 12, 13, and 14 are the cam followers 21a). , 22a and 20a), the radial passage 17 is formed to communicate with the groove passage 47 only in the range (D) + (A). The hydraulic plunger 70, the groove passage 47, the control passages 16, 17 and the like constitute a timing control mechanism of the present invention.

The oil pump 80 is driven by, for example, an internal combustion engine and is constituted by a lubricating oil pump that sucks and discharges oil in an oil pan 82, and a part of the discharged oil is supplied to the axial passage 16 through a switching valve 81. It is being supplied. The switching valve 81 is configured by, for example, an electromagnetic valve having three ports and two positions, and supplies a part of the oil discharged from the oil pump 80 to the axial passage 16 in accordance with the operation state of the internal combustion engine.
The position and the second position where the axial passage 16 communicates with the oil pan 82 are selectively switched and controlled.

The operation of this embodiment having the above configuration will be described below.

Referring to FIGS. 2 and 5, when the internal combustion engine is operated in a high-speed rotation range, the switching valve 81 communicates the axial passage 16 with the oil pan 82. Therefore, the hydraulic plunger 70 is at the position shown in FIG. 2 by the urging force of the spring 73, and the communication between the pressure chamber 69 and the reservoir chamber R is blocked by the check ball 67. Therefore, the movable column 62 is immovably held with respect to the body 61 by the pressure oil in the pressure chamber 69. In this state, when the high-speed cam 14 slides on the cam follower 20a to push down the high-speed rocker arm 20 by the rotation of the camshaft 11, the high-speed rocker arm 20
As shown by the broken line in FIG. 5, the high-speed rocker arm 20 is swung about the insertion portion between the c and the head 62b and the swing fulcrum B. As a result, the low-speed rocker arms 21 and 2
2 swings integrally with the high-speed rocker arm 20 in a state where the swinging end portion 20b of the high-speed rocker arm 20 abuts on the connecting portion of the swinging end portions 21b and 22b, and the intake valve 30 is moved to the position shown in FIG. The intake hole 36a is opened and closed according to the lift curve at the time of the high lift shown. At this time, the fixed supports 50 and 51 are
2 and the camshaft 11 on the same axis, so that the low-speed and high-speed rocker arms 21 and 2
The swing of 2, 20 is not restricted by the fixed columns 50, 51. Further, at the time of the above-described high lift, the radial passage 17 repeatedly communicates with and shuts off from the groove passage 47, but the hydraulic plunger 70 is held at the retracted position shown in FIG.

In the rotation range of FIG. 4E during the above-described high lift, even if the switching valve 81 is switched to supply the discharge oil from the oil pump 80 to the axial passage 16, FIGS. As shown in FIG. 7, the radial passage 17 does not communicate with the groove passage 47 and no hydraulic pressure is supplied to the hydraulic chamber 77, so that the lift amount does not change during the lift. In this state, when the camshaft 11 further rotates to reach the rotation range shown in FIG. 4D, the radial passage 17 and the groove passage 47 communicate with each other as shown in FIG. Is supplied. This causes the hydraulic plunger 70 to move to the left in FIG. 2 against the spring 73, but at this time, the lift has not been completed yet, and the pressure chamber 69 is driven by the high-speed cam 14 applied to the moving support 62. The check ball 67 cannot be released by the pin 71 because the check ball 67 is pressed against the opening end 61 c by the pressure of the pressure chamber 69 in addition to the urging force of the spring 68. . Therefore, the high lift state is maintained during the lift, and the lift amount does not change during the lift. Then, in this state, when the camshaft 11 further rotates to reach the rotation range of FIG. 4A, the base circle of the high-speed cam 14 is again moved to the high-speed rocker arm 20 as shown in FIGS. The sliding contact with the cam follower 20a causes the pressure chamber 69 to be no longer pressurized by the moving column 62, the hydraulic plunger 20 to move leftward in FIG. 2 against the spring 73, and the pin 71 against the check ball 67 against the spring 68. And move.

The rotation range is such that the base circle of the high-speed cam 14 is in sliding contact with the cam follower 20a of the high-speed rocker arm 20 again, and in the rotation range of FIG. Is supplied to the hydraulic chamber 77 via the switching valve 81, the axial passage 16, the radial passage 17, the groove passage 47 and the passage 48, and when the hydraulic plunger 70 moves against the spring 73, the pin 71 The pressure chamber 69 and the reservoir chamber R are communicated with each other through the passage 61b. Thereby, the pressure oil filling the pressure chamber 69 flows into the reservoir chamber R, and the pressure due to the pressure oil acting on the other end of the movable support column 62 disappears. In this state, the rotation of the camshaft 11 causes the high-speed cam 14 to rotate.
Slides on the cam follower 20a to push down the high-speed rocker arm 20.
0 is the rocking end 20b and the rocker arm 2 for low speed.
As shown in FIGS. 7 to 9, the first and second swing ends 21 b and 22 b swing as shown in FIGS.
On the other hand, the low-speed rocker arms 21 and 22 are swung about the swing fulcrum A by the low-speed cams 12 and 13, whereby the intake valve 30 opens and closes the intake hole 36a in the lift curve at the time of low lift shown in FIG. I do. At this time, the moving support 62
Is movable with respect to the body 61 due to the disappearance of the pressure due to the pressure oil, and as shown in FIGS. 7 to 9 against the urging force of the spring 64 in accordance with the swing of the high-speed rocker arm 20. Move to (lost motion). Therefore, the rocking of the low-speed rocker arms 21 and 22 is not restricted. Further, at the time of the above-described low lift, the radial passage 17 repeatedly communicates with and shuts off from the groove passage 47, but the hydraulic plunger 70 is held at the retracted position shown in FIG.

Further, even if the switching valve 81 is switched and the axial passage 16 communicates with the oil pan 82 in the rotation range of FIG.
Also, as shown in FIG. 7, the radial passage 17 does not communicate with the groove passage 47 and the hydraulic pressure is not reduced in the hydraulic chamber 77, so that the hydraulic plunger 70 is held at the forward position. Therefore, the lift amount does not change during the lift. In this state, when the camshaft 11 further rotates to reach the rotation range of FIG. 4D, the radial passage 17 and the groove passage 47 communicate with each other, and the hydraulic chamber 77 communicates with the oil pan 82 as shown in FIG. Is done. As a result, the hydraulic plunger 70 is
3, the pin 71 returns to the retracted position shown in FIG. At this time, the lift has not been finished yet, and the movable support 62 rises by the urging force of the spring 64 as the camshaft 11 rotates. Due to the pressure drop in the pressure chamber 69 caused by the rise of the moving column 62, the check ball 67 moves until the base circle of the high-speed cam 14 slides on the cam follower 20a as shown in FIG. The open state is maintained (until the position of FIG. 5 is reached). Then, when reaching the position shown in FIG. 5, the check ball 67 closes the passage 61b and switches to the high lift state.

As described above, in this embodiment, the hydraulic plunger 70 is synchronized with the rotation of the camshaft 11.
Hydraulic plunger 70 by opening and closing the oil passage to the
Is restricted, the lift amount is variable during the lift. In particular, during the low lift due to the lost motion of the movable support column 62, the lost motion of the movable support column 62 is prevented, and the switching to the high lift is reliably prevented. . As a result, during the lost motion of the movable support column 62 (in a state where the movable support column 62 is sunk with respect to the body 61), switching to the high lift causes the entire valve train system dimensions to be inconsistent.
When the cam returns to the base circle and the valve is seated, it is possible to reliably prevent the tapping sound from being generated or damaged. Moreover, only one switching valve 81 for selectively communicating the hydraulic chamber 77 with the oil pump 80 or the oil pan 82 may be provided, and the switching valve is appropriately switched according to the rotation speed and load of the internal combustion engine regardless of the lift state. Since it is only necessary to control, the increase in cost can be prevented at the same time, and the control can be simplified.

In the above embodiment, the embodiment in which the present invention is applied to the intake valve 30 has been described. However, the present invention can be applied to an exhaust valve.

[0032]

As described above, according to the present invention, by providing the timing control mechanism which allows the support column to move only while the rocker arm is in sliding contact with the base circle of the cam,
It is reliably prevented that the lift amount is changed during the lift, in particular, switching to the high lift during the low lift. Thus, switching to the high lift during the low lift causes the entire valve train system dimensions to be inconsistent, and the occurrence of hitting noise or breakage when the cam returns to the base circle and the valve is seated is reliably prevented, and a simple operation is achieved. With this configuration, the reliability of the variable valve operating device can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a variable valve operating device for an internal combustion engine according to the present invention.

FIG. 2 is a sectional view showing a fixed support, a movable support, a timing control mechanism, and the like in the embodiment shown in FIG.

FIG. 3 is a sectional view of a journal portion of the camshaft in the embodiment shown in FIG.

FIG. 4 is a diagram showing a relationship between a lift state of a valve and a rotation angle of a cam shaft in the embodiment shown in FIG. 1;

FIG. 5 is a cross-sectional view showing a state in which a cam follower slides on a base circle and a radial passage communicates with a groove passage in the embodiment shown in FIG. 1;

FIG. 6 is a cross-sectional view showing a state in which the cam follower is in sliding contact with the base circle and the communication between the radial passage and the groove passage is started in the embodiment shown in FIG. 1;

FIG. 7 is a sectional view showing a state at the time of a maximum lift in the embodiment shown in FIG. 1;

FIG. 8 is a cross-sectional view showing a state in which the radial passage and the groove passage are communicated in the latter half of the lift in the embodiment shown in FIG. 1;

FIG. 9 is a sectional view showing a lift state in the embodiment shown in FIG. 1;

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 camshaft 12, 13 low-speed cam 14 high-speed cam 16 axial passage (control oil passage) 17 radial passage (control oil passage) 20 high-speed rocker arm 21, 22 low-speed rocker arm 30 intake valve (intake / exhaust valve) ) 40 Cylinder head 47 Groove passage (timing control mechanism) 50, 51 Fixed support 60 Hydraulic lifter 62 Moving support 70 Hydraulic plunger (timing control mechanism) 80 Oil pump 81 Switching valve A First swing fulcrum B Second swing fulcrum

Claims (3)

[Claims] 1. A camshaft rotatably disposed on a cylinder head of an internal combustion engine and rotated in synchronization with a crankshaft, and integrally provided on the camshaft according to the rotation of the camshaft. A rocker arm that is swung by sliding contact with a cam to lift and open and close the intake / exhaust valve, and a variable mechanism that makes a swing fulcrum of the rocker arm variable, the lift amount of the intake / exhaust valve or In a variable valve apparatus for an internal combustion engine having a variable opening / closing timing, the variable mechanism is mounted on the cylinder head so as to support the rocker arm swinging, and one or more hydraulic mechanisms are applied to one end of the cylinder head. And a control oil for releasing the hydraulic pressure formed in the camshaft, comprising a plurality of columns which can be moved to the cylinder head by being released. An internal combustion engine provided with a timing control mechanism for synchronizing the opening and closing of the road with the rotation of the camshaft and permitting the movement of the column only while the rocker arm is in sliding contact with the base circle of the cam. Variable valve gear. 2. A high-speed cam rotatably disposed on a cylinder head of an internal combustion engine, rotated in synchronization with a crankshaft, and having a low-speed cam and a nose portion larger than a nose portion of the low-speed cam. A low-speed rocker arm that is swung about a first swing fulcrum by sliding contact with the low-speed cam in response to rotation of the camshaft to lift and open and close the intake / exhaust valve; A high-speed rocker arm that is swung about a second swing fulcrum by sliding contact with the high-speed cam in response to the rotation of the camshaft, and lifts an intake / exhaust valve through the low-speed rocker arm to open and close. And a second high-speed rocker arm.
A variable mechanism for varying the swing fulcrum, wherein the lift amount or opening / closing timing of the intake / exhaust valve is varied. The cylinder head is attached to the cylinder head so as to be able to support the movement, and is constituted by a moving column that can be moved to the cylinder head by releasing the hydraulic pressure applied to one end thereof, and is formed in the camshaft. The opening and closing of the control oil passage for releasing the oil pressure is synchronized with the rotation of the camshaft, and the movement of the moving support is performed by the low-speed and high-speed rocker arms with the base circles of the low-speed and high-speed cams. A variable valve train for an internal combustion engine, comprising a timing control mechanism that permits only during sliding contact. 3. A pressure chamber formed at one end of the moving post in the hole by slidably fitting the moving post into a sliding hole formed in the cylinder head; A one-way valve interposed between a chamber and an oil passage formed in the cylinder head, the one-way valve allowing only oil to flow from the oil passage to the pressure chamber, wherein the timing control mechanism comprises: A release position in which one end pushes the one-way valve to open the valve, and a return position in which one end is separated from the one-way valve to maintain the one-way valve closed, The other end has a plunger movable by supplying and discharging hydraulic pressure via the control oil passage, and the control oil passage has at least the low-speed and high-speed rocker arms with the low-speed and high-speed cams. Is in sliding contact with each base circle 3. The variable valve train for an internal combustion engine according to claim 2, wherein the valve is opened only during the interval.