JPH066884B2 - 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 relates to a state in which a plurality of rocker arms for operating an engine valve are connected between adjacent rocker arms in a state in which both rocker arms are connected in a high speed operation state of the engine and The present invention relates to a valve operating device for an internal combustion engine provided with a connection switching mechanism capable of switching between a state in which both rocker arms are disconnected in a low speed operation state.

(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 at the time of low speed operation of the engine, and the high speed engine 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, in the high-speed operating state of the engine, both adjacent rocker arms are connected by the connection switching mechanism, but if the connection switching mechanism malfunctions for some reason and the two rocker arms remain disconnected, the engine is The operation of the engine valve does not correspond to the high speed operation during the high speed operation, and the operation of the engine becomes defective.

The present invention has been made in view of such circumstances, and has a relatively small inertial weight and enables a switching operation with excellent responsiveness to switch the operating mode of an engine valve. It is an object of the present invention to provide a valve operating device for an internal combustion engine, which can surely bring the engine valve into a high-speed operation mode during high speed operation.

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve this object, according to the present invention, the connection switching mechanism is provided in both rocker arms so as to be coaxial when the engine valve is closed. A cylinder hole, a switching piston that is slidably fitted in the cylinder hole so as to be movable between a position for connecting both rocker arms and a position for releasing the connection, and the switching piston for connecting the both rocker arms. A hydraulic chamber capable of exerting drive oil pressure for driving to the release side, and a spring exerting a spring force for biasing and driving the switching piston toward the connection side of both rocker arms when the drive oil pressure is released.

(2) Operation According to the above configuration, 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 are 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. Even if the hydraulic pressure supply system to the hydraulic chamber fails, adjacent rocker arms can be reliably connected during high-speed operation of the engine.

(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 an auxiliary-combustion-chamber intake valve 3c as an engine valve that controls intake to the auxiliary-combustion chamber (not shown). The valves 3a, 3b, 3c are forcibly opened and closed according to the rotational movement of the camshaft 4, but during low load operation, the valves 3a, 3b, 3c of some cylinders are deactivated. . For example, if the first to fourth numbers are sequentially assigned from one of the cylinders to the other,
The valves 3a, 3b, 3c of the first and fourth cylinders respectively correspond to the forced valve actuation mechanisms 5a, 5 during high load operation.
b, 5c is forcibly operated, but individually corresponds to the hydraulic connection switching mechanism 6 during low load operation.
The operation can be stopped by the switching operation of a, 6b and 6c. On the other hand, the valves 3a, 3b of the second and third cylinders,
3c is an always corresponding forced valve operating mechanism 7a, 7b, 7
By c, it can be constantly operated regardless of the load level.

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 lock nut 13 screwed into 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, and has almost no involvement in the opening / closing operation of the intake valve 3a.

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 support seat 25 has a contact seat 2
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 The switching piston 29 fitted in the cylinder hole 36, the timing piston 30 slidably fitted in the cylinder hole 36, and the switching piston 2 when hydraulic pressure is applied.
A hydraulic chamber 40 defined between the timing piston 30 and the second free rocker arm 18 and a switching piston 29 in order to exert hydraulic pressure for moving 9 to the release position side.
A spring 31 for urging the spring toward the connecting position side,
Trigger plate 32 that regulates the operation of the timing piston 30
With.

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, in order from the drive rocker arm 19 side, a pin sliding portion 38 having the same diameter as the guide hole 33, and a piston sliding portion 39 having a smaller diameter than the sliding portion 38.
And a hydraulic chamber 40 having a diameter larger than that of the piston sliding portion 39. The pin sliding portion 38 and the piston sliding portion 3 are formed.
A restricting step portion 41 facing the drive rocker arm 19 side is formed between the portions 9. The switching piston 29 is slidable on the pin sliding portion 38, abuts against the regulation step portion 41, and its movement toward the second free rocker arm 18 is regulated. In this state, the second free rocker arm 18 and the drive rocker arm 19 are switched. It is connected via a piston 29.

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 piston sliding portion 39 with its open end facing the drive rocker arm 19 side. The cylindrical body 43 has a pressing collar 44 that slides on the piston sliding portion 39 at one end, and is slid 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, a through hole 46 is formed at one end of the cylindrical body 43, and the inside of the timing piston 30 is communicated 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 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. 50. 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. Further, the shape of the contact portion 54 is such that the trigger plate 32 is rotated around the pin 50 in the counterclockwise direction in FIG. 5 as the distance L ₁ between the cam surface 55 and the center of the pin 50 gradually decreases as described above. The distance L ₂ from the outer peripheral surface of the abutting portion 54, which is in sliding contact with the cam surface 55, to the center of the pin 50 is formed so as to become smaller around the pin 50 in the clockwise direction of 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 pin 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 operates toward the drive rocker arm 19 side, but when the intake valve 3a is closed,
Since the restricting portion 53 of the trigger plate 32 is fitted in the fitting groove 47, the operation of the bottomed cylindrical body 42 is prevented. Intake valve 3a
While the valve is being opened, the regulating portion 5 of the trigger plate 32
Since 3 disengages from the fitting groove 47, the operation of the bottomed cylindrical body 42 is allowed, and the bottomed cylindrical body 42 pushes the pressing collar 4 of the cylindrical body 43.
4 and presses the switching piston 29 through the pressing collar 44. At this time, when the opening operation of the intake valve 3a is completed, the sliding resistance between the switching piston 29 and the pin sliding portion 38 decreases, so that the switching piston 29 moves from the pin sliding portion 38 of the cylinder hole 36. Cylinder hole 3
It is pushed into 3. Therefore, the connection state between the second free rocker arm 18 and the drive rocker arm 19 is released, and the drive rocker arm 19 is moved to the second free rocker arm 1
Regardless of the operation of No. 8, the posture of keeping the intake valve 3a in the closed state is maintained.

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 may be set to be large as described above.

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 opening operation, the trigger plate 32
Is removed from the fitting groove 48, the timing piston 3
When the switching piston 29 presses the timing piston 30, the switching piston 29 slides on the cylinder hole 31 and the pin sliding portion 38. As a result, the second free rocker arm 18 and the drive rocker arm 19 are connected again, the drive rocker arm 19 swings together with the second free rocker arm 18, 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 switching piston 29 can smoothly slide on the pin sliding portion 38. In order to be carried out, 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 arranged.
And are smoothly curved. That is, when the connection between the second free rocker arm 18 and the drive rocker arm 19 is released, the drive rocker arm 19 moves between the upper lifter 12 and the lower lifter 11 only slightly as the tip of the engaging arm 28 moves up and down. Since the second free rocker arm 18 and the drive rocker arm 19 can be reconnected, the axis of the switching piston 29 and the axis of the timing piston 30 may be slightly deviated from each other.
Even in such a case, the pin sliding portion 3 of the switching piston 29
The radius of curvature R ₁ of the end peripheral edge 29a of the switching piston 29 and the radius of curvature R ₂ of the opening end edge 36a of the cylinder hole 36 are set so that the sliding movement of the cylinder 8 can be performed automatically and smoothly. .

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 open 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. The connecting 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 78 is moved according to 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 constantly opened and closed during the rotating operation of the camshaft 4, that is, during the operation of the engine, regardless of the level of the load. 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
The disengagement of the switching piston 29 from the pin sliding portion 38 when the free rocker arm 18 and the drive rocker arm 19 are both operating is avoided, and thus the switching piston 2
9 is smoothly pushed back into the cylinder hole 33 without being caught in the cylinder hole 36.

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. Accordingly, in each of the hydraulic connection switching mechanisms 6a to 6c, the switching piston 29 slides on the pin 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. When the trigger plate 32 is disengaged from the fitting groove 48 when the valve 18 is opened, the timing piston 30 and the switching piston 29 are allowed to move. Therefore, when the second free rocker arm 18 and the drive rocker arm 19 are stationary, the switching piston 2 is moved as when the second free rocker arm 18 and the drive rocker arm 19 are disconnected.
9 is smoothly slid on the pin sliding portion 38 of the cylinder hole 36.

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 edge 36 a of the cylinder hole 36.
₂ is set so that the sliding of the switching piston 29 to the pin sliding portion 38 is automatically and smoothly performed.
Even if the axis of the switching piston 29 and the axis of the cylinder hole 36 are slightly deviated from each other, the switching piston 29 is smoothly slid on the pin sliding portion 38 of the cylinder hole 36.

The second free rocker arm 18 and the drive rocker arm 19 are reconnected by the sliding of the switching piston 29 to the pin sliding portion 38, and in the first and fourth cylinders, the valves 3a to 3c are opened and closed by the forced valve operating mechanisms 5a to 5c. The operation is restarted. At this time, in the second and third cylinders, the opening and closing operations of the valves 3a to 3c by the forced valve actuation mechanisms 7a to 7c are always continued, so that the valves 3a to 3c of all the cylinders are eventually ended.
c is forcibly opened and closed, and 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 resting state, and the intake valve 3a is prevented from entering a resting state during high-speed operation of the engine.

Here, the operation sequence of the hydraulic connection switching mechanisms 6a and 6b corresponding to the intake valve 3a and the exhaust valve 3b, that is, the operation suspension sequence of the intake valve 3a and the exhaust valve 3b will be examined. When the intake valve 3a is stopped prior to the intake valve 3a, the phenomenon of blowback to the intake system occurs as shown in FIG. In FIG. 9, (a) shows the intake valve 3
A is a lift, (b) is a lift of the exhaust valve 3b, (c) is a cylinder pressure, reference numeral i is an ignition timing, and P is an atmospheric pressure. As is apparent from FIG. 9, since the intake valve 3a is open when the exhaust valve 3b is in a rest mode, that is, when the exhaust valve 3b is closed, a blowback phenomenon to the intake system occurs in the range shown by the diagonal lines. This is because when the operation of the intake valve 3a and the exhaust valve 3b is stopped and then the operation is restored,
The same is true when the operation is restored before the exhaust valve 3b.

If such a blowback phenomenon to the intake system occurs, clogging of the carburetor, noise, engine stall, etc. occur, which is inconvenient.

On the other hand, when the operation is stopped, the intake valve 3a is stopped before the exhaust valve 3b, and when the operation is restored, the exhaust valve 3a is stopped.
When b is operated prior to or simultaneously with the intake valve 3a, it becomes as shown in FIGS. 10 (a), (b) and (c). That is, when the intake valve 3a is closed as shown in FIG. 10 (a) when the exhaust valve 3b is open as shown in FIG. 10 (b), FIG. 10 (c).
Even if the cylinder pressure is in the pressurized state within the range indicated by the diagonal line
The bubbling phenomenon cannot occur.

Therefore, as described above, when the operation is stopped, the intake valve 3a is stopped first, and when the operation is returned to the intake valve 3a and the exhaust valve 3b.
Next, an embodiment will be described in which the two are simultaneously operated to prevent the occurrence of the blowback phenomenon.

FIG. 11 shows another embodiment of the present invention, in which a hydraulic connection switching mechanism 79a for the intake valve 3a and a hydraulic connection switching mechanism 79b for the exhaust valve 3b include a pair of check valves 80,
It is connected via 81. That is, in the both hydraulic connection switching mechanisms 79a and 79b, the hydraulic chamber 82 is partitioned by the timing piston 85 into a rear chamber 83 and a front chamber 84, and the timing piston 85 is disposed in the rear chamber 8.
3 is actuated by the spring 86 when no hydraulic pressure is applied, and the switching piston 88 against the spring force of the springs 86, 87 when hydraulic pressure is applied to the rear chamber 83.
Is movably provided between an operation rest position for pushing back into the cylinder hole 89. Moreover, the second free rocker arm 18 on the intake valve 3a side communicates with the front chamber 84 when the timing piston 85 is in the operating position and is closed by the timing piston 85 when the timing piston 85 is in the operation rest position. Oil passages 90 and 91, and an oil passage 29 that is closed by the timing piston 85 when the timing piston 85 is in the operating position and communicates with the rear chamber 84 when the timing piston 85 is in the operation rest position.
And an oil passage 93 that is in constant communication with the rear chamber 83. Further, in the second free rocker arm 18 on the exhaust valve 3b side, the oil passage 94 which is always in communication with the rear chamber 83, and the timing piston 85 is in communication with the rear chamber 83 when the timing piston 85 is in the operating position, and the timing piston 85 is in the rest position. And an oil passage 95 that is closed when the vehicle is in position.

The oil passage 93 is connected to an oil passage 96 that supplies hydraulic pressure from the electromagnetic switching valve 68 (see FIG. 3). Further, the oil passage 92 and the oil passage 94 are connected via an oil passage 97, and a check valve 80 forcing only the flow of the pressure oil from the oil passage 92 side to the oil passage 94 side is provided in the middle of the oil passage 97. Intervened. In the oil passage 97, between the check valve 80 and the oil passage 94 on the exhaust valve 3b side, an oil passage 98 branched from the oil passage 97 is connected to the oil passage 90 on the intake valve 3a side. In the middle of 98, a check valve 81 that allows only pressure oil to flow to the oil passage 90 side
Is installed. Further, the oil passage 91 on the intake valve 3a side and the oil passage 95 on the exhaust valve 3b side are opened to an oil pan (not shown).

Next, the operation of this embodiment will be described. The intake valve 3a
When the operation of the exhaust valve 3b is stopped, the hydraulic pressure is supplied from the oil passage 96 to the rear chamber 83 of the hydraulic chamber 82 of the hydraulic connection switching mechanism 79a via the oil passage 93. As a result, the timing piston 85 of the hydraulic connection switching mechanism 79a is
Operates to push the switching piston 88 into the cylinder hole 89, the second free rocker arm 18 and the drive rocker arm 19 are disconnected, and the operation of the intake valve 3a is stopped. By the movement of the timing piston 85 to the operation rest position, the oil passage 92 communicates with the rear chamber 83, and the hydraulic pressure is supplied to the rear chamber 83 of the hydraulic connection switching mechanism 79b via the check valve 80. Therefore, in the hydraulic connection switching mechanism 79b, the timing piston 85 operates to push the switching piston 88 into the cylinder hole 89, and the operation of the exhaust valve 3b is stopped. Thus, when the operation is stopped, the intake valve 3a is stopped first, and then the exhaust valve 3b is stopped.

Next, when the valve operation is restored, the hydraulic pressure is released from the oil passage 96. As a result, the timing piston 85 of the hydraulic connection switching mechanism 79a retracts due to the spring force of the springs 86, 87, and the switching piston 88 causes the second free rocker arm 1 to move.
8 and the drive rocker arm 19 are connected. However, at the same time, since the oil passage 90 communicates with the front chamber 84, the hydraulic pressure in the rear chamber 83 of the hydraulic connection switching mechanism 79b is released via the check valve 81. Therefore, the timing pistons 85 of the hydraulic connection switching mechanisms 79a and 79b are simultaneously retracted to connect the second free rocker arm 18 and the drive rocker arm 19.

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 present invention, the connection switching mechanism includes the cylinder holes formed in both rocker arms so as to be coaxial when the engine valve is closed, the position connecting the rocker arms, and the connection. A switching piston that is slidably fitted in the cylinder hole so as to be movable between a position for releasing and
A hydraulic chamber capable of exerting drive oil pressure for driving the switching piston to the connection release side of both rocker arms, and a spring force for urging and driving the switching piston to the connection side of both rocker arms when the drive oil pressure is released. Since it is equipped with a spring that exerts its effect, it is possible to avoid increasing the size of both rocker arms by arranging the connection switching mechanism between both rocker arms while avoiding an increase in weight, and switching with excellent responsiveness by switching the hydraulic pressure. Operation can be realized. Moreover, even if the hydraulic pressure supply system leading to the hydraulic pressure chamber fails, the two rocker arms are connected by the springs, so that the engine valve can be reliably operated during high speed operation of the engine.

[Brief description of drawings]

1 to 8 show one embodiment of the present invention,
1 is a longitudinal sectional view, FIG. 2 is a plan view showing a part of FIG. 1 omitted, and FIG. 3 is an exploded perspective view showing a forced valve mechanism, a hydraulic connection switching mechanism, and a hydraulic pressure supply mechanism. 4 is a sectional view showing the inside of the hydraulic connection switching mechanism, FIG. 5 is a sectional view showing the corresponding arrangement of the trigger plate with the rocker shaft and the timing piston, and FIG. 6 is a relative position between the timing piston and the switching piston. FIG. 7 is an enlarged sectional view showing the end of the switching piston and the end of the cylinder hole.
The figure is an exploded perspective view of the always forced valve mechanism, FIG. 9 and FIG.
FIG. 0 is a diagram showing changes in the cylinder pressure due to the hydraulic connection switching order of the intake valve and the exhaust valve. (A) shows the intake valve lift, (b) shows the exhaust valve lift, and (c) shows the cylinder pressure. FIG. 11 is a sectional view of another embodiment of the present invention. 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, 79a, 79b ... Connection switching mechanism, 17, 1
8, 19 ... Rocker arm, 29, 88 ... Switching piston,
31, 87 ... Spring, 33, 36, 89 ... Cylinder hole, 4
0, 82 ... Hydraulic chamber

Claims (1)

[Claims] 1. A plurality of rocker arms for operating an engine valve, between adjacent rocker arms, the two rocker arms are disconnected when the engine is operating at a high speed and the rocker arms are disconnected when the engine is operating at a low speed. In the valve operating device of the internal combustion engine, which is provided with a connection switching mechanism capable of switching between the states, the connection switching mechanism is a cylinder hole formed in each of the rocker arms so as to be coaxial when the engine valve is closed, A switching piston that is movable between a position where both rocker arms are connected and a position where the connection is released and is slidably fitted in the cylinder hole; and the switching piston is driven to the connection release side of both rocker arms. A hydraulic chamber that can generate drive oil pressure and a spring force that urges the switching piston to the connecting side of both rocker arms when the drive oil pressure is released. A valve gear of an internal combustion engine, characterized in that it comprises a spring which.