JPH0613843B2 - Valve drive for internal combustion engine - Google Patents

Description

Detailed Description of the Invention A. OBJECT OF THE INVENTION (1) Industrial field of application The present invention is, among a plurality of rocker arms for operating an engine valve, between two adjacent rocker arms, a state in which both rocker arms are connected and a state in which both rocker arms are disconnected. The present invention relates to a valve operating device for an internal combustion engine, which is provided with a connection switching mechanism capable of switching between and.

(2) Prior art In such a valve operating system for an internal combustion engine, the connection of adjacent rocker arms is released to suspend the operation of a part of the intake valve or the exhaust valve as the engine valve when the engine is operating at a low speed, and the engine is operated at high speed. Japanese Utility Model Laid-Open No. 57-193905 discloses a structure in which both rocker arms are connected during operation to reduce fuel consumption and improve output.

(3) Problems to be Solved by the Invention By the way, in the above-mentioned conventional one, connection and disconnection of a rocker arm that engages with an engine valve and a free rocker arm that is rockably driven by a cam are switched by engagement / disengagement driving of a key. I am trying. The key is fixed to a cylindrical member slidably fitted to the rocker shaft, and both rocker arms are swingably supported by the cylindrical member. Inevitably, the cylindrical member has a larger size than that directly supported by the above, and the cylindrical member has a total length larger than the combined width of both rocker arms for supporting both rocker arms regardless of the switching operation. Therefore, the inertial weight of the valve train becomes large.

Further, the switching operation of the connection switching mechanism needs to be performed when both the rocker arms are in a stationary state with the engine valve closed, and if the switching operation start timing deviates, smooth switching operation is not performed, It may cause abnormal noise or damage.

The present invention has been made in view of such circumstances, and has a relatively small inertial weight and enables switching operation with excellent responsiveness so as to switch the operation mode of the engine valve, and the connection. An object of the present invention is to provide a valve operating device for an internal combustion engine, which can smoothly perform a switching operation of a switching mechanism.

B. Configuration of the Invention (1) Means for Solving the Problems According to the first invention for achieving the above object, the connection switching mechanism is provided in both rocker arms so as to be coaxial when the engine valve is closed. And a switching piston that is slidably fitted in the cylinder hole by making the cylinder hole and a position for connecting both rocker arms movable between a position for releasing the connection and the position for releasing the connection, and driving the switching piston. A hydraulic chamber capable of exerting hydraulic pressure and a spring for urging the switching piston against the hydraulic pressure of the hydraulic chamber are provided, and one of the rocker arms adjacent to each other is provided with a rocking arm depending on the rocking position of both rocker arms. And a movement restricting means for restricting the movement of the switching piston.

Further, according to the second aspect of the invention, the connection switching mechanism has a cylinder resistance which is formed in each rocker arm so as to be coaxial when the engine valve is closed, a position where the rocker arms are connected, and a position where the connection is released. And a hydraulic chamber capable of exerting hydraulic pressure for driving the switching piston, the switching piston being slidably fitted into the cylinder hole so as to be movable between the rocker arms. In order to regulate the movement of the switching piston, a timing piston configured to expand and contract by exerting a spring force in the extension direction and abutting the switching piston is slidably fitted in one of the cylinder holes. At the same time, when the rocker arm swings in the valve opening direction, the engagement state with the timing piston can be released, and the trigger plate is engaged with the timing piston.

(2) Operation According to the configuration of the first aspect of the present invention, the connection switching mechanism is switched by switching the hydraulic pressure in the hydraulic chamber, and connection and disconnection between the free rocker arm and the drive rocker arm is switched. Thus, it is possible to dispose the connection switching mechanism between both rocker arms without increasing the size of the drive rocker arm and the free rocker arm, and the provision of the connection switching mechanism does not increase the weight. The movement regulating means regulates the movement timing of the switching piston, so that a smooth switching operation is realized.

Further, according to the configuration of the second aspect of the invention, the connection switching mechanism is switched by switching the hydraulic pressure in the hydraulic chamber, and connection and disconnection between the free rocker arm and the drive rocker arm is switched. Thus, it is possible to dispose the connection switching mechanism between both rocker arms without increasing the size of the drive rocker arm and the free rocker arm, and the provision of the connection switching mechanism does not increase the weight. By switching between engagement and disengagement of the trigger plate with the timing piston, the movement of the switching piston is restricted according to the rocking position of the rocker arm, and a smooth switching operation is realized.

(3) Examples Hereinafter, examples of the present invention will be described with reference to the drawings.
First, in FIG. 1 and FIG. 2, the internal combustion engine E is
A multi-cylinder, for example a 4-cylinder, torch ignition type internal combustion engine,
The cylinder head 1 of each cylinder has an intake valve 3a and an exhaust valve 3b as engine valves that control intake and exhaust to the main combustion chamber 2.
And a sub-combustion chamber intake valve 3c as an engine valve for controlling intake to the sub-combustion chamber (not shown) are provided so as to be freely opened and closed. Each of the valves 3a, 3b, 3c has a camshaft 4
The valve 3a, 3b, 3c of some cylinders is deactivated during low load operation. For example, if the first to fourth numbers are assigned in order from one of the cylinders to the other, the valves 3a, 3b, 3c of the first and fourth cylinders are forced to correspond individually during high load operation. Valve mechanism 5a,
5b, 5c forcibly actuates it, but during low-load operation, the operation is stopped by the corresponding switching operation of the hydraulic connection switching mechanisms 6a, 6b, 6c. On the other hand, the valves 3a, 3 of the second and third cylinders
b and 3c are always corresponding forced valve operating mechanisms 7a and 7c
b and 7c enable constant operation regardless of the level of the load.

The forced valve operating mechanisms 5a, 5b, 5c and the hydraulic connection switching mechanisms 6a, 6b, 6c individually corresponding to the valves 3a, 3b, 3c of the first and fourth cylinders have the same configuration, respectively. Further, the valves 3a, 3b, 3 of the second and third cylinders
Always-operated valve mechanism 7a, 7b, 7c individually corresponding to c
Also have the same configuration. Therefore, in the following description, the forced valve operating mechanism 5a, the hydraulic connection switching mechanism 6a, the constant forced valve operating mechanism 7a, and their related parts will be described in detail, and the other forced valve operating mechanisms 5b and 5c and hydraulic pressures will be described. Type connection switching mechanism 6b, 6c, constant forced valve mechanism 7b, 7
Detailed description of c and parts related thereto will be omitted.

In the first cylinder, the intake valve 3a is movably inserted into a guide cylinder 8 provided vertically through the cylinder head 1, and a male screw 9 is engraved on the upper end of the intake valve 3a. . A retainer 10 is screwed onto the male screw 9, and the lower lifter 11 is screwed with the downward movement restricted by the retainer 10. Also, at a position spaced upward from the lower lifter 11, the male screw 9 has an upper lifter 12
The upper lifter 12 has a male screw 9
The upward movement is restricted by the rock night 13 screwed to the. The forced valve mechanism 5a is engaged between the lower lifter 11 and the upper lifter 12, and the swing motion of the forced valve mechanism 5a causes the intake valve 3a to move vertically.
That is, the compulsory opening / closing operation is performed.

A coil spring 14 is provided between the upper portion of the cylinder head 1 and the retainer 10 so as to surround the intake valve 3a, and the spring force of the spring 14 urges the intake valve 3a in the closing direction. However, the spring force of the spring 14 is weak enough to maintain the closed state of the intake valve 3a.
Almost does not participate in the opening / closing operation of.

In FIG. 3, the forced valve mechanism 5a is provided on the cam shaft 4 disposed above the central portion of the cylinder head 1 and integrally provided with the valve closing cam 15 and the valve opening cam 16 and the valve closing cam 15. First free rocker arm 17 that swings in contact
And a second free rocker arm 18 that swings in conjunction with the first free rocker arm 17 while contacting the valve opening cam 16.
And the second free rocker arm 18 can be freely connected and disconnected, and the drive rocker arm 1 can be connected to the intake valve 3a.
9 and a rocker shaft 20 arranged in parallel with the camshaft 4 so as to commonly support the rocker arms 17, 18 and 19 in common.

The camshaft 4 is rotatably supported on the upper portion of the cylinder head 1 and is rotationally driven at a rotation ratio of 1/2 in synchronization with the rotation of the engine. The rocker shaft 20 is fixedly supported on the upper portion of the cylinder head 1 obliquely above the cam shaft 4. The first free rocker arm 17 is integrally provided with a cam slipper 21 slidingly contacting the valve closing cam 15, and the second free rocker arm 18 is integrally provided with a cam slipper 22 slidingly contacting the valve opening cam 16. Moreover, both cam slippers 21 and 22 are arranged on both sides of a virtual straight line 23 connecting the centers of the cam shaft 4 and the rocker shaft 20. That is, the cam slipper 21 of the first free rocker arm 17 is connected to the intake valve 3 with respect to the virtual straight line 23.
The side a is in sliding contact with the valve closing cam 15, and the cam slipper 22 of the second free rocker arm 18 is in sliding contact with the valve opening cam 16 on the side opposite to the intake valve 3a with respect to the virtual straight line 23. Further, a contact seat 24 facing upward is provided at an upper part of the first free rocker arm 17 on the intake valve 3a side, and the second free rocker arm 18 has a support portion 2 extending above the contact seat 24.
5 is integrally provided. The abutment seat 2 is attached to the support portion 25.
A tappet screw 26 abutting against the screw 4 is screwed so as to be able to move forward and backward, and a lock nut 27 is screwed on the tappet screw 26 in order to prevent loosening. The tappet screw 26 causes the first and second free rocker arms 17 and 18 to interlock with each other. That is, when the valve closing cam 15 rotates the first free rocker arm 17 in the direction in which the abutment seat 24 pushes the tappet screw 26, the second free rocker arm 18 is rotated in the same direction as the first free rocker arm 17. The direction in which the second free rocker arm 18 pushes the contact seat 24 with its tappet screw 26 by the valve opening cam 16 (clockwise direction in FIG. 1).
When pivoted to, the first free rocker arm 17 is pivoted in the same direction as the second free rocker arm 18.

The drive rocker arm 19 is integrally provided with an engagement arm 28 that extends toward the intake valve 3a and has a bifurcated tip end portion. The tip end of the engagement arm 28 holds the intake valve 3a from both sides. In this way, the lower lifter 11 and the upper lifter 12 are engaged with each other. Therefore, when the second free rocker arm 18 and the drive rocker arm 19 are in the connected state, the rotational movement of the first free rocker arm 17 in the valve closing direction is transmitted to the drive rocker arm 19 via the second free rocker arm 18, and the engagement arm is engaged. The intake valve 3a closes when the upper lifter 12 is lifted upward by rotating 28 upward. The lower lifter 11 is pushed downward by the engaging arm 28 by the pivotal movement of the drive rocker arm 19 that is integral with the pivotal movement of the second free rocker arm 18 in the valve opening direction, and the intake valve 3a is opened. The valve operates.

Second free rocker arm 18 and drive rocker arm 19
A hydraulic connection switching mechanism 6a for connecting and disconnecting the two is provided between the second free rocker arm 18 and the drive rocker arm 19, and when the hydraulic connection switching mechanism 6a operates, the second The connection state between the free rocker arm 18 and the drive rocker arm 19 is released.
When the connection state is released in such a manner, the operation of the first and second free rocker arms 17 and 18 is changed to the drive rocker arm 1
9, the intake valve 3a remains closed by the spring force of the spring 14.

Referring also to FIG. 4, the hydraulic connection switching mechanism 6a is
A cylinder hole 36 formed in the second free rocker arm 18 along an axis parallel to the axis of the rocker shaft 20 and a rocker shaft on the drive rocker arm 19 so as to be coaxial with the cylinder hole 36 when the intake valve 3a is closed. Cylinder hole 33 bored parallel to the axis of 20 and movable between the position connecting second free rocker arm 18 and drive rocker arm 19 and the position releasing the connection, and slidable in cylinder hole 33, 36 , A hydraulic chamber 40 for exerting an oil pressure to move the switching piston 29 to the connection release position side when hydraulic pressure is applied, and a switching piston 29 facing the connection position side. And a spring 31 for urging. Further, the second free rocker arm 18 is provided with movement restricting means R for restricting the movement of the switching piston 29 in accordance with the swing position of the rocker arm 18, and the movement restricting means R mutually extend the spring in the extension direction. A timing piston 30, which is configured to exert a force and expand and contract, and slidably fitted into the cylinder hole 36 while contacting the switching piston 29, and swinging of the second free rocker arm 18 in the valve opening direction. And a trigger plate 32 which is capable of releasing the engagement state with the timing piston 30 and engages with the timing piston. The hydraulic chamber 40 is thus defined between the timing piston 30 and the second free rocker arm 18.

The drive rocker arm 19 includes a second free rocker arm 18
A bottomed cylinder hole 33 that is open toward the side and that is parallel to the axis of the rocker shaft 20 is bored. The end of the cylinder hole 33 on the side opposite to the second free rocker arm 18 is formed on the drive rocker arm 19. Air vent hole 3 drilled
It is communicated to the outside through 4. The switching piston 29 is formed in a hollow bottomed cylindrical shape having a through hole 35 at the bottom, and is slidably fitted into the cylinder hole 33 with its open end facing the air vent hole 34 side. A spring 31 is interposed between the closed end of the cylinder hole 33 and the switching piston 29. Therefore, the switching piston 29 is urged by the spring force of the spring 31 toward the direction protruding from the cylinder hole 33, that is, toward the second free rocker arm 18 side.

On the other hand, the second free rocker arm 18 is provided with a cylinder hole 36 corresponding to the cylinder hole 33 and parallel to the axis of the rocker shaft 20, and the end of the cylinder hole 36 opposite to the drive rocker arm 19 is formed. The part is closed by a plug 37. The cylinder hole 36 has a first piston sliding portion 38 having the same diameter as the cylinder hole 33, a second piston sliding portion 39 having a smaller diameter than the sliding portion 38, and a second piston sliding portion 39 in order from the drive rocker arm 19 side. A hydraulic pressure chamber 40 having a larger diameter than that of the first and second piston sliding portions 38, 39 is formed between the first and second piston sliding portions 38, 39 to form a restriction step portion 41 facing the drive rocker arm 19 side. The switching piston 29 is slidable on the first piston sliding portion 38, and the regulating step portion 41
The second free rocker arm 18 and the drive rocker arm 19 are connected to each other via the switching piston 29 in this state.

The timing piston 30 includes a bottomed cylindrical body 42 and a cylindrical body 43 which are slidably fitted to each other. The bottomed cylindrical body 42 slides on the second piston sliding portion 39 with its open end facing the drive rocker arm 19 side. The cylindrical body 43 is
It has a pressing flange 44 that slides on the second piston sliding portion 39 at one end and slides on the bottomed cylindrical body 42. A spring 45 is interposed between the bottom of the bottomed cylindrical body 42 and one end of the cylindrical body 43, and the cylindrical body 43 is urged toward the drive rocker arm 19 side by the spring force of the spring 45. Moreover, the cylindrical body 4
A through hole 46 is formed at one end of the timing piston 30, and the inside of the timing piston 30 communicates with the outside through the through hole 35 of the switching piston 29 and the air vent hole 34 of the cylinder hole 33. Therefore, the relative movement of the cylindrical body 43 and the bottomed cylindrical body 42 in the axial direction can be freely performed without resistance due to pressurization or depressurization of the air in the timing piston 30.

The lengths of the bottomed cylindrical body 42 and the cylindrical body 43 are such that the bottom of the bottomed cylindrical body 42 abuts on the plug 37 and the pressing piston 4 of the cylindrical body 43 on the switching piston 29 abutting on the regulation step 41.
4 when they abut, the pressing collar 44 and the bottomed cylindrical body 42
A fitting groove 47 into which the trigger plate 32 can be fitted is formed between the ends of the. Further, a fitting groove 48 capable of fitting the trigger plate 32 is also formed on the outer circumference of the bottomed cylindrical body 42, and the position of the fitting groove 48 is a timing piston when hydraulic pressure acts on the hydraulic chamber 40. When the switching piston 29 is pressed by 30 and the connection state of the second free rocker arm 18 and the drive rocker arm 19 is released, the trigger plate 32
Are set to fit.

The second free rocker arm 18 is provided with a groove 49 slidably engaged with the trigger plate 32, and the trigger plate 32 slidably engaged with the groove 49 is moved to a second position by a pin 50 parallel to the axis of the rocker shaft 20. It is pivotally supported by the free rocker arm 18. E-shaped retaining rings 51 and 52 are fitted on both ends of the pin 50, respectively.

In FIG. 5, the trigger plate 32 has a restricting portion 53 extending from the position of the pin 50 to the timing piston 30 side, and an abutting portion 5 extending from the position of the pin 50 to the rocker shaft 20 side.
4 are provided respectively, and the restricting portion 53 can be fitted into the fitting grooves 47, 48 of the timing piston 30. Further, the abutting portion 54 abuts on a cam surface 55 formed by cutting the outer circumference of the rocker shaft 20. Further, basically, the spring 56, which is formed in a substantially U-shape and pivotally supported at both ends of the pin 50, abuts on the upper portion of the restricting portion 53, so that the spring 5
Both ends of 6 are brought into contact with the side surface of the second free rocker arm 18 on the rocker shaft 20 side. Due to the spring force of the spring 56, the restricting portion 53 of the trigger plate 32 causes the timing piston 3 to move.
The direction closer to the 0 side, that is, around the pin 50
It is urged in the direction to rotate clockwise in the figure. On the other hand, the cam surface 55 is pinned by the second free rocker arm 18 in the valve opening direction, that is, as the second free rocker arm 18 and the pin 50 rotate around the rocker shaft 20 in the counterclockwise direction in FIG. The distance L ₁ between the cam surface 55 and the center of the pin 50 on the straight line connecting the centers of the rocker shaft 20 and the rocker shaft 20 is gradually reduced to form a flat surface parallel to one diameter line of the rocker shaft 20. To be done. The shape of the contact portion 54 is the counterclockwise direction of FIG. 5 about the pin 50 triggers plate 32 in response to the distance L ₁ between the centers of the cam surface 55 and pin 50 gradually becomes smaller as described above In order to rotate the pin 50, the distance L ₂ from the outer peripheral surface of the abutting portion 54, which comes into sliding contact with the cam surface 55, to the center of the pin 50 becomes smaller as it goes clockwise around the pin 50 in FIG. It As a result, when the second free rocker arm 18 rotates in the valve opening direction, the trigger plate 32 moves together with the second free rocker arm 18 into the rocker shaft 20.
5, while rotating in the counterclockwise direction in FIG. 5 against the biasing force of the spring 56, in the counterclockwise direction in FIG. It will be separated from the groove 47 or 48.

In such a hydraulic connection switching mechanism 6a, the hydraulic chamber 4
When the hydraulic pressure does not act on 0, the switching piston 29
Is slidably engaged with the first piston sliding portion 38 of the cylinder hole 36 by the spring force of the spring 31 to connect the second free rocker arm 18 and the drive rocker arm 19. Therefore, the drive rocker arm 19 swings integrally with the second free rocker arm 18, and the intake valve 3 a is opened / closed via the engagement arm 28.

On the other hand, when hydraulic pressure acts on the hydraulic chamber 40, the bottomed cylindrical body 42 of the timing piston 30 is pressed toward the drive rocker arm 19 side, but when the intake valve 3a is closed, the restricting portion 53 of the trigger plate 32 is formed. Is fitted in the fitting groove 47, the movement of the bottomed cylindrical body 42 is prevented. Since the restriction portion 53 of the trigger plate 32 is disengaged from the fitting groove 47 while the intake valve 3a is in the valve opening operation, the bottomed cylindrical body 42 is formed.
Is allowed, the bottomed cylindrical body 42 contacts the pressing flange 44 of the cylindrical body 43, and the switching piston 2 is connected via the pressing flange 44.
Press 9. At this time, since the sliding resistance between the switching piston 29 and the first piston sliding portion 38 is relatively large when the second free rocker arm 18 and the drive rocker arm 19 are in operation, the switching piston 29 is moved to the cylinder hole 3
However, when the intake valve 3a is seated, that is, when the second free rocker arm 18 and the drive rocker arm 19 are in a substantially stationary state, the space between the switching piston 29 and the first piston sliding portion 38 is not pushed. Since the sliding resistance is small, the switching piston 29 has the first hole of the cylinder hole 36.
It separates from the piston sliding portion 38 and is pushed into the cylinder hole 33. Therefore, the connection state of the second free rocker arm 18 and the drive rocker arm 19 is released, and the drive rocker arm 19 maintains the posture in which the intake valve 3a is closed regardless of the operation of the second free rocker arm 18.

In FIG. 6, the diameter of the switching piston 29 is such that the timing piston 30 always slides when the second free rocker arm 18 and the drive rocker arm 19 are disconnected from each other, regardless of the swing motion of the second free rocker arm 18. Set to be in contact. That is, when the second free rocker arm 18 oscillates about the rocker shaft 20 within the range of the angle α, the axes of the timing piston 30 and the switching piston 29 coincide with each other as shown by the solid line in FIG. The diameter of the switching piston 29 is set such that the timing piston 30 and the switching piston 29 are in slidable contact with each other in the shaded portion even if the timing piston 30 is angularly displaced from the present state to the position indicated by the chain line. The diameter of the timing piston 30 is set to the second free rocker arm 1
8 may be set large so that the switching piston 29 is always in sliding contact with the drive rocker arm 19 and the drive rocker arm 19 in the disconnected state.

Second free rocker arm 18 and drive rocker arm 19
The hydraulic pressure in the hydraulic chamber 40 is released when the valves are reconnected. As a result, the switching piston 29 is pressed toward the second free rocker arm 18 side by the spring force of the spring 31, but at this time also, when the second free rocker arm 18 is in the valve closing operation, the trigger plate 32 is Since it fits in the fitting groove 48, the operation of the timing piston 30 is restricted, and the movement of the switching piston 29 is blocked. When the second free rocker arm 18 shifts to the valve closing operation, the trigger plate 32
Is removed from the fitting groove 48, the timing piston 3
The bottomed cylindrical body 42 can be moved at 0, and the bottomed cylindrical body 42 is moved backward by the spring force of the spring 45 until it abuts on the plug 37. Second free rocker arm 1
When 8 is in a stationary state and the axes of the cylinder holes 33 and 36 substantially coincide with each other, the switching piston 29 shifts the timing piston 3
The first cylinder sliding portion 38 of the cylinder hole 36 slides while pressing the cylindrical body 43 of 0. As a result, the second free rocker arm 18 and the drive rocker arm 19 are connected again, and the drive rocker arm 19 is connected to the second free rocker arm 1
The intake valve 3a is rocked together with the valve 8, and the intake valve 3a is opened.

When the second free rocker arm 18 and the drive rocker arm 19 are reconnected as described above, even if the axis of the switching piston 29 and the axis of the cylinder hole 36 are slightly deviated from each other, the sliding of the switching piston 29 to the first piston sliding portion 38 is prevented. In order to ensure smooth operation, as shown in FIG. 7, the opening end edge 36a of the cylinder hole 36 and the end peripheral edge 29a of the switching piston 29 are smoothly curved. Ie the second
When the connection between the free rocker arm 18 and the drive rocker arm 19 is released, the drive rocker arm 19 is moved between the upper lifter 12 and the lower lifter 11 at a slight angle such that the tip of the engaging arm 28 moves up and down. The axis of the switching piston 29 and the axis of the timing piston 30 may be slightly deviated when the second free rocker arm 18 and the drive rocker arm 19 are reconnected. Even in such a case, the curved radius of curvature R ₁ of the end peripheral edge 29a of the switching piston 29 and the cylinder hole 36 are adjusted so that the switching piston 29 slides on the first piston sliding portion 38 automatically and smoothly. The curvature radius of curvature R _{2 of the} opening edge 36a is set.

Here, the structure for supplying hydraulic pressure to the hydraulic connection switching mechanism 6a will be described. Referring again to FIG. 3, the hydraulic pressure supply source 57 includes a hydraulic pump 58 and an accumulator 59. The hydraulic pump 58 is configured such that the plunger 61 in the cylinder 60 is reciprocally driven by the drive rod 62 to suck the working oil from the suction valve 63 and discharge the working oil from the discharge valve 64. Is driven by a drive cam 65 integrally provided on the camshaft 4. Further, the plunger 61 is biased by a spring 66 so that it is always in contact with the drive rod 62. An accumulator 59 is connected in the middle of a discharge oil passage 67 leading to the discharge valve 64, and the discharge oil passage 67 is further connected to an electromagnetic switching valve 68.

The electromagnetic switching valve 68 can switch between a first switching mode in which the discharge oil passage 67 is connected to the oil passage 69 and a second switching mode in which the oil passage 69 is connected to the release oil passage 70.
When 1 is excited, it is in the first switching mode, and when solenoid 71 is demagnetized, it is in the second switching mode.

The oil passage 69 is connected to an oil passage 72 formed concentrically in the rocker shaft 20. Moreover, on the rocker shaft 20,
A communication hole 73 is formed in a side wall of the second free rocker arm 18 corresponding to the hydraulic chamber 40, and the communication hole 73 is connected to the hydraulic chamber 40 via an oil passage 74 formed in the second free rocker arm 18. Communicated. Therefore, the solenoid 71
When the electromagnetic switching valve 68 is set to the first switching mode, the hydraulic oil from the hydraulic pump 58 is supplied to the hydraulic chamber 40, the solenoid 71 is demagnetized, and the electromagnetic switching valve 68 is switched to the second switching mode. At this time, the hydraulic pressure in the hydraulic chamber 40 is released.

Next, the constant forced valve mechanism 7a will be described with reference to FIG. 8. The constant forced valve mechanism 7a contacts the valve closing cam 15 and swings the first rocker arm 75 and the valve opening cam 16. A second rocker arm 76 that swings in conjunction with the first rocker arm 75.
Is integrally provided with an engagement arm 78 that engages with the intake valve 3a. That is, in the constant forced valve mechanism 7a, the engaging arm 78 is provided integrally with the second rocker arm 76, so that the engaging arm 28 moves in accordance with the swing of the first and second rocker arms 75 and 76. The intake valve 3a is constantly moved up and down, and the intake valve 3a is always opened and closed during the rotational operation of the camshaft 4, that is, during the operation of the engine, regardless of the load level. In addition, this 8th
In the figure, the same reference numerals are attached to the portions corresponding to the above-mentioned forced valve mechanism 5a.

Next, the operation of this embodiment will be described. The internal combustion engine E
Is operating at a high load, no hydraulic pressure is applied to the hydraulic chambers 40 of the hydraulic connection switching mechanisms 6a to 6c, and therefore the second free rocker arm is not used in the forced valve operating mechanisms 5a to 5c. 18 and the drive rocker arm 19 are connected via a switching piston 29. For this reason,
In the first and fourth cylinders, a first free rocker arm 17 that abuts on the valve closing cam 15 and swings, and a second free rocker arm 17 that abuts on the valve opening cam 16 and swings in synchronization with the first free rocker arm 17. The drive rocker arm 19 swings by the free rocker arm 18, and the valves 3a to 3c are forcibly opened and closed. In the second and third cylinders, the first rocker arm 75 that abuts on the valve closing cam 15 and swings.
And a second rocker arm 76 that abuts the valve opening cam 16 and swings in conjunction with the first rocker arm 75.
a to 3c are forcibly opened and closed. In this way, by forcibly driving the valves 3a to 3c, the cam profiles of the valve closing cams 15 and the valve opening cams 16 can be made into ideal shapes to improve the intake and exhaust efficiencies. Moreover, the spring force of the spring 14 is set to a weak value such that the closed state of each valve 3a to 3c is maintained, and each valve 3a to 3c is set.
It can be largely independent of the operation of 3c. Therefore, the repulsive force of the spring 14 at the time of valve opening operation becomes small, and the valve operating load is reduced, so that it is possible to reduce fuel consumption.

When the internal combustion engine E is operated at a low load, the electromagnetic switching valve 68 is excited to drive the oil passages 69, 72, the communication hole 73, and the oil passage 74 from the hydraulic connection switching mechanisms 6a to 6c for the first and fourth cylinders. A hydraulic pressure is supplied to the hydraulic chamber 40 of 6c. As a result, each timing piston 30 is pressed and driven toward the drive rocker arm 19 side, and each switching piston 29 is pushed back into the cylinder hole 33 against the spring force of the spring 31. At this time, when the second free rocker arm 18 is closed, the movement of the timing piston 30 is restricted because the trigger plate 32 is fitted in the fitting groove 47, and the second free rocker arm 18 is opened. The movement of the timing piston 30 is allowed when the trigger plate 32 is disengaged from the fitting groove 47 during valve operation. This allows the second
In response to the valve closing operation of the free rocker arm 18, the bottomed cylindrical body 42 of the timing piston 30 causes the pressing collar 44 of the cylindrical body 43 to move.
Forward until it contacts the second free rocker arm 18
Since the sliding resistance between the switching piston 29 and the first piston sliding portion 38 is relatively large when both the drive rocker arm 19 and the drive rocker arm 19 are operating,
When the second free rocker arm 18 and the drive rocker arm 19 are in a substantially stationary state and the sliding resistance becomes small, the switching piston 29 does not get caught in the cylinder hole 36 without being disengaged from the piston sliding portion 38. , Is smoothly pushed back into the cylinder hole 33.

When the switching piston 29 is pushed back into the cylinder hole 33, the connection state between the second free rocker arm 18 and the drive rocker arm 19 is released, and the drive rocker arm 1
9 is independent of the movement of the second free rocker arm 18,
The spring 14 maintains the valve closed state.

At this time, since the diameter of the switching piston 29 is set large as described with reference to FIG. 6, the timing piston 3 is irrespective of the swinging motion of the second free rocker arm 18.
0 is always in sliding contact with the switching piston 29, and the switching piston 29 does not project to the second free rocker arm 18 side. Further, the fitting groove 48 of the bottomed cylindrical body 42 of the timing piston 30 is located at a position corresponding to the trigger plate 32, and when the second free rocker arm 18 is closing the valve, the trigger plate 32 is fitted in the fitting groove 48. Mating.

In this way, during low load operation of the internal combustion engine E, the first
The operation of the valves 3a to 3c in the fourth cylinder is stopped, and only the valves 3a to 3c in the second and third cylinders are forcibly operated by the forced valve actuation mechanisms 7a to 7c. Therefore, fuel efficiency during low load operation is significantly reduced.

Next, assume a case where the internal combustion engine E returns from low load operation to high load operation. In this case, the solenoid 71 of the electromagnetic switching valve 68 is demagnetized, and the hydraulic pressure in each hydraulic chamber 40 in the first and fourth cylinders is released. In response to this, in each of the hydraulic connection switching mechanisms 6a to 6c, the switching piston 29 slides on the first piston sliding portion 38 of the cylinder hole 36 while pressing the timing piston 30 by the spring force of the spring 31. However, when the second free rocker arm 18 is closed, the trigger plate 32 is fitted in the fitting groove 48, so that the timing piston 30 and the switching piston 29 are prevented from moving, and the second free rocker arm 18 is blocked. 1
When the valve 8 is opened, the trigger plate 32 is inserted into the fitting groove 48.
By moving away from, the timing piston 30 and the switching piston 29 are allowed to move. Therefore,
Second free rocker arm 18 and drive rocker arm 19
When the second free rocker arm 18 and the drive rocker arm 19 are in a substantially stationary state, the switching piston 29 is smoothly slid on the first piston sliding portion 38 of the cylinder hole 36 as in the case of releasing the connection.

Moreover, the radius of curvature R ₁ of the end peripheral edge 29 a of the switching piston 29 and the radius of curvature R ₁ of the opening end edge 36 a of the cylinder hole 36.
₂ is set so that the switching piston 29 slides on the first piston sliding portion 38 automatically and smoothly, and therefore the axis of the switching piston 29 and the axis of the cylinder hole 36 are slightly deviated from each other. However, the switching piston 29 is smoothly slid on the first piston sliding portion 38 of the cylinder hole 36.

The second free rocker arm 18 and the drive rocker arm 19 are connected again by the sliding engagement of the switching piston 29 with the first piston sliding portion 38, and in the first and fourth cylinders, the forced valve actuation mechanisms 5a to 5c respectively operate the valves 3a to 3c. The opening and closing operation of is restarted. At this time, in the second and third cylinders, the valves 3a to 3c are always operated by the forced valve operating mechanisms 7a to 7c.
Since the opening and closing operations of No. 2 are continued, the valves 3a to 3c of all cylinders are forcibly opened and closed, and the high load operation of the internal combustion engine E is achieved.

By the way, the hydraulic connection switching mechanism 6a is configured by slidably fitting the switching piston 29 and the timing piston 30 into the cylinder holes 33 and 36 provided in the second free rocker arm 18 and the drive rocker arm 19. , The second free rocker arm 18 and the drive rocker arm 1 by disposing the hydraulic connection switching mechanism 6a.
9 does not increase in size, and the second free rocker arm 18 and the drive rocker arm 19 are
Since it is directly supported by No. 0 and there is no need for a component that increases the inertial weight, it is possible to suppress the increase in the inertial weight and to promptly perform the switching operation by the hydraulic pressure switching of the hydraulic chamber 40. Therefore, the responsiveness can be improved. Moreover, in the hydraulic connection switching mechanism 6a, the switching piston 29 and the timing piston 3 are
No. 0 is formed in a hollow shape, whereby the inertial weight can be further reduced.

Further, since the hydraulic connection switching mechanism 6a operates by releasing the hydraulic pressure in the hydraulic chamber 40, even if there is a failure in the hydraulic supply system leading to the hydraulic chamber 40,
It is prevented that the intake valve 3a remains in a rest state.

In the above embodiment, the valve closing cam 15 and the valve opening cam 1
Although a multi-cylinder internal combustion engine has been described in which the valves are forced to open and close by means of first and second free rocker arms 17 and 18 respectively abutting the six, the present invention provides a single cam for each valve. It can also be implemented in connection with a multi-cylinder internal combustion engine in which a rocker arm is swung in accordance with the rotational movement of the cam.

C. EFFECTS OF THE INVENTION As described above, according to the first aspect of the present invention, the connection switching mechanism has a cylinder hole that is formed in each of the rocker arms so as to be coaxial when the engine valve is closed, and a position that connects the rocker arms. A switching piston that is slidably fitted in the cylinder hole so as to be movable between the disconnection position, a hydraulic chamber that can exert hydraulic pressure to drive the switching piston, and a hydraulic chamber of the hydraulic chamber. A spring for urging the switching piston against the hydraulic pressure is provided, and one of the mutually adjacent rocker arms is provided with a movement restricting means for restricting the movement of the switching piston in accordance with the rocking position of both rocker arms. Since the rocker arms are provided, it is possible to avoid an increase in the size of both rocker arms, and it is possible to realize a switching operation with excellent responsiveness by switching the hydraulic pressure. Moreover, a smooth switching operation is realized by regulating the movement start timing of the switching piston by the action of the movement regulating means.

Further, according to the second aspect of the invention, the connection switching mechanism has a cylinder hole formed in each rocker arm so as to be coaxial when the engine valve is closed, a position for connecting the rocker arms, and a position for releasing the connection. And a hydraulic chamber capable of exerting hydraulic pressure for driving the switching piston, the switching piston being slidably fitted into the cylinder hole so as to be movable between the rocker arms. In order to regulate the movement of the switching piston, a timing piston configured to expand and contract by exerting a spring force in the extension direction and abutting the switching piston is slidably fitted in one of the cylinder holes. At the same time, when the rocker arm swings in the valve opening direction, the engagement state with the timing piston can be released and the trigger plate is engaged with the timing piston. The avoiding are possible, it is possible to realize an excellent switching operation of the response due to the hydraulic pressure of the switching. Moreover, by engaging and disengaging the trigger plate with the timing piston in accordance with the rocking position of the rocker arm, the movement start timing of the switching piston is regulated and a smooth switching operation is realized.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a longitudinal sectional view, FIG. 2 is a plan view showing a part of FIG. 1 omitted,
3 is an exploded perspective view showing a forced valve mechanism, a hydraulic connection switching mechanism and a hydraulic pressure supply mechanism, FIG. 4 is a sectional view showing the inside of the hydraulic connection switching mechanism, and FIG. 5 is a rocker shaft of a trigger plate and FIG. 6 is a sectional view showing the corresponding arrangement with the timing piston, FIG. 6 is a simplified diagram showing the relative position of the timing piston and the switching piston, and FIG. 7 is an enlarged sectional view showing the end of the switching piston and the end of the cylinder hole. 8 and 9 are exploded perspective views of the always forced valve mechanism. 3a ... intake valve as engine valve, 3b ... exhaust valve as engine valve, 3c ... intake valve for auxiliary combustion chamber as engine valve,
6a, 6b, 6c ... Connection switching mechanism, 17, 18, 19
...... Rocker arm, 29 ...... Switching piston, 30 ...... Timing piston, 31 ...... Spring, 32 ...... Trigger plate,
33, 36 ... Cylinder hole, 40 ... Hydraulic chamber, R ... Movement restricting means

Claims (2)

[Claims] 1. A coupling switching mechanism is provided between adjacent rocker arms among a plurality of rocker arms for operating an engine valve, which is capable of switching between a state where both rocker arms are coupled and a state where both rocker arms are uncoupled. In the valve operating system for an internal combustion engine, the connection switching mechanism releases cylinders, cylinder holes formed in both rocker arms so as to be coaxial when the engine valve is closed, positions where the rocker arms are connected, and the connection is released. Any one of rocker arms that are adjacent to each other and that includes a switching piston that is slidably fitted in the cylinder hole and is movable between a position and a hydraulic chamber that can exert hydraulic pressure to drive the switching piston. On one side, a movement restricting means for restricting the movement of the switching piston according to the rocking positions of both rocker arms is provided. The valve device. 2. A connection switching mechanism is provided between adjacent rocker arms among a plurality of rocker arms for operating an engine valve, which can switch between a state in which both rocker arms are connected and a state in which both rocker arms are disconnected. In the valve operating system for an internal combustion engine, the connection switching mechanism releases cylinders, cylinder holes formed in both rocker arms so as to be coaxial when the engine valve is closed, positions where the rocker arms are connected, and the connection is released. A switching piston that is slidably fitted in the cylinder hole so as to be movable between a position and a hydraulic chamber capable of exerting hydraulic pressure for driving the switching piston; Accordingly, in order to regulate the movement of the switching piston, a timing piston that is configured to be capable of expanding and contracting by exerting a spring force in the extension direction and contacting the switching piston is provided. Note: The trigger plate is slidably fitted in one of both cylinder holes, and the trigger plate is engaged with the timing piston by enabling the engagement state with the timing piston to be released when the rocker arm swings in the valve opening direction. A valve operating system for an internal combustion engine, comprising: