JPS6357805A - Valve mechanism for internal combustion engine - Google Patents

Abstract

PURPOSE:To attain more sophisticated control of a valve mechanism using a simple construction, by providing a plural number of rocker arms for driving intake (exhaust) valves and providing a connection change-over means capable of making change-over of connection/disconnection by means of hydraulic power between every neighboring two of said rocker arms. CONSTITUTION:A cam shaft 2 driven synchronizing with engine revolution is provided with the first and the second low speed cams 3, 4 and a high speed cam 5, so that the rotation of said cam shaft 2 may open or close a pair of intake valves 1a, 1b through the first to the third rocker arms 7-9. In the present case, change-over means 21, 22 are provided, the first one 21 of which can change over from the state where said rocker arms 7, 8 are allowed of relative angular displacement to each other to the state where the both arms and solidly connected to each other, or the reverse, while the second one 22 can do the similar change-over as the above for said rocker arms 7, 9. Each of change-over devices 21, 22 is formed of a piston 23 which is driven by hydraulic oil led via oil passage 34, 42, etc. from hydraulic oil passages 32, 33, the latter passages being formed in a rocker shaft 2 being divided from each other by a partition 31.

Description

Detailed Description of the Invention A0 Object of the Invention (1) Industrial Application Field The present invention is directed to opening and closing intake valves or exhaust valves in response to the rotational movement of a camshaft that is rotationally driven in synchronization with the rotation of an engine. The present invention relates to a valve operating system for an internal combustion engine in which a plurality of rocker arms are pivotally supported on a rocker shaft in order to perform the same operation.

(2) Prior Art In such a valve train, the pulp diameter, pulp timing, and valve lift amount are generally set with emphasis on relatively high-speed rotation in order to obtain high output.

By the way, if the steep air valve is driven with the same pulp timing and the same lift amount from low speed range to high speed range, the amount of intake air per unit time will differ depending on each rotation speed, so the speed of the mixture flow into the combustion chamber will change. different. In other words, at low speeds, the air-fuel mixture flow rate decreases, the charging efficiency decreases, and proper mixing and atomization of the air-fuel mixture within the combustion chamber cannot be achieved, resulting in a slow combustion rate. As a result, stable combustion cannot be obtained, and low-speed operation becomes unstable with rotational fluctuations.
This results in a decrease in the fuel ratio due to a decrease in combustion efficiency, and a decrease in the non-king limit due to a decrease in combustion speed.

Therefore, in order to solve this problem, there is a system in which part of the intake valve or exhaust valve is closed during low-speed operation, and both intake valves or exhaust valves are opened and closed during high-speed operation. It is disclosed in Publication No. 59-226216.

(3) Problems to be Solved by the Invention In the above-mentioned conventional technology, valve train control is performed separately for low speed and high speed. However, if valve train control is performed by dividing the operating range more finely, It will be possible to improve engine output and stable low-speed operation under a wider range of operating conditions, and it will also be possible to improve the fuel ratio.

Therefore, the present applicant installed three cams adjacent to each other on a camshaft, and two of the three rocker arms slidingly contacted with each cam drive the intake valve or exhaust valve to open and close. Between the rocker arms,
A valve train has already been proposed in which connection switching means capable of switching connection and disconnection between both hook arms are provided so as to be able to operate independently of each other in accordance with the action of hydraulic pressure.

According to such a valve train, valve train control can be performed in more segmented speed ranges.

By the way, in the above-mentioned valve train, the oil passage for individually supplying hydraulic pressure to each connection switching means is formed by press-fitting and fixing a steel ball into the rocker shaft and dividing the inside of the rocker shaft into two. Therefore, in such a structure, it is necessary to supply hydraulic pressure from both sides of the rocker shaft in the axial direction. Therefore, in a valve train for a multi-cylinder internal combustion engine, the hydraulic pressure supply circuit becomes complicated.

The present invention has been made in view of the above circumstances, and has the following three points.
It is an object of the present invention to provide a valve train for an internal combustion engine that performs valve train control divided into three or more speed ranges and has a simplified hydraulic pressure supply circuit.

B0 Structure of the Invention fil Means for Solving the Problems According to the present invention, connection switching means capable of switching between connection and disconnection between mutually adjacent rocker arms are provided so that they can be connected and disconnected from each other according to the action of hydraulic pressure. A plurality of hydraulic pressure supply passages individually communicating with each of the connection switching means are provided in the rocker shaft and separated from each other through partition walls extending in the axial direction.

(2) Operation By individually operating each connection switching means according to the operating state of the engine, the rocker arm operation Li can be varied, and more detailed valve train control becomes possible. Moreover, since the plurality of hydraulic pressure supply passages separated within the rocker shaft by partition walls extending in the axial direction individually communicate with each connection switching means, the hydraulic pressure supply circuit is simplified.

(3) Examples Examples of the present invention will be explained below with reference to the drawings.
First, in FIGS. 1 and 2 showing a first embodiment of the present invention, a pair of intake valves 1a and lb are provided in the engine body of an internal combustion engine.
are arranged, and these intake valves 1a, lb are provided with a first low-speed cam 3, a second cam that are integrally provided on a camshaft 2 that is driven at a rotation ratio of 2 in synchronization with the rotation of the engine. A first cam is pivotally supported by a low-speed cam 4, a high-speed cam 5, and a rocker shaft 6 parallel to the camshaft 2. 2nd and 30th
・7 kaarm? , 8.9 are driven to open and close.

The camshaft 2 is rotatably disposed above the engine body, and the high-speed cam 5 is connected to both intake valves 1a.

It is integrally provided on the camshaft 2 at a position corresponding to between lbs. Moreover, the first low-speed cam 3 has a shape suitable for low-speed operation of the engine, and the high portion 3 has a relatively small amount of outward protrusion along the radial direction of the camshaft 2.
It has a. Further, the high-speed cam 5 has a shape suitable for high-speed operation of the engine, and the amount of radially outward protrusion of the camshaft 2 is larger than the high-position portion 3a of the first low-speed cam 3, and the high-speed cam 5 has a shape suitable for high-speed engine operation. It has a high portion 5a that covers a wider center angle range than the portion 3a. Furthermore, the second low speed cam 4
The camshaft 2 also has a shape suitable for low-speed operation of the engine, and has a high portion 4a that protrudes outward in a relatively small amount along the radial direction of the camshaft 2, and this high portion 4a is larger than the high portion 3a. It's also small.

The rocker shaft 6 is fixedly arranged below the camshaft 2. This rocker shaft 6 has a high-speed cam 5.
A 10th claw arm 7 corresponding to the rocker arm 7, a 20th claw arm 8 corresponding to the first low speed cam 3, and a 30th claw arm 9 corresponding to the second low speed cam 4 are pivotally supported. Cam slippers 7a, 8a, 9a are provided on the top of the cams 7a, 8a, 9a for sliding contact with each cam 3, 4.5. Also second.
The 30th arm arms 8 and 9 extend above the intake valves 1a and lb, and have the intake valve 1a at their tips.

A tappet head 12.13 that can come into contact with the upper end of lb is screwed in such a way that it can move forward and backward.

On the other hand, flanges 14, 15 are provided at the top of the intake valves 1a, lb, and valve springs 16, 17 surrounding the intake valves 1a, lb are provided between the flanges 14, 15 and the engine body. is interposed. These valve springs 16,17 cause the intake valve 1a to
, lb are urged upward, that is, in the valve closing direction.

In FIG. 3, on the lower surface of the end of the tenth hook arm 7,
A bottomed cylindrical lid 19 is brought into contact as a pressing means, and this lifter 19 is urged upward by a lifter spring 20 with a relatively weak spring force interposed between the lifter 19 and the engine body.

As a result, the cam slipper 7a of the tenth claw arm 7 comes into resilient sliding contact with the high-speed cam 5.

In FIG. 4, the first and 20th hook arms 7.8 are in sliding contact with each other, and can be switched between a state in which relative angular displacement thereof is possible and a state in which the double-ended hook arms 7.8 are integrally connected. A possible first connection switching means 21 connects the first and second
It is provided between the arms 7 and 8. The first and 30th anchor arms 7.9 are also in sliding contact with each other, and the first and 30th anchor arms 7.9 are switchable between a state in which relative angular displacement thereof is possible and a state in which the double-ended link arms 7.9 are integrally connected. Two connection switching means 22 are provided between the first and thirtieth hook arms 7°9.

The first and second connection switching means 21 and 22 basically have the same configuration, and hereinafter, only the configuration of the first connection and switching means 21 will be described in detail, and the configuration of the second connection and switching means 2 will be described in detail.
A detailed explanation of 2 will be omitted.

The first connection switching means 21 includes a piston 23 that is movable between a position where the first and the 207th arm 7.8 are connected and a position where the connection is released, and a stopper 24 that restricts the movement of the piston 23. , and a spring 25 that biases the stopper 24 to move the piston 23 toward the disconnection position.

The tenth hook arm 7 has a first guide hole 26 that is open toward the twentieth hook arm 8 side and is parallel to the rocker shaft 6, and the closed end side of the first guide hole 26 is bored. A small diameter portion 28 is provided via the stepped portion 27 . A piston 23 is slidably fitted into the first guide hole 26 , and a hydraulic chamber 29 is defined between the piston 23 and the closed end of the first guide hole 26 .

The 20th lever arm 8 has a second guide hole 35 opened toward the 10th anchor arm 7 side corresponding to the first guide hole 26, and a disk plate is inserted into the second guide hole 35. A shaped stopper 24 is slid together. A small diameter portion 37 is provided on the closed end side of the second guide hole 35 via a regulating step portion 36, and an insertion hole 38 coaxial with the small diameter portion 37 is provided at the closed end.
is drilled. Moreover, a guide rod 39 coaxially and integrally provided with the stopper 24 is inserted into the insertion hole 38. Furthermore, a coiled cane spring 25 surrounding the guide rod 39 is interposed between the stopper 24 and the closed end of the second guide hole 35.

The axial length of the piston 23 is such that one end thereof has a stepped portion -27
When the stopper 24 comes into contact with the regulating step 36, the other end is located between the first and twentieth hook arms 7.8, and when the stopper 24 enters the second guide hole 35 until it comes into contact with the regulating step 36. , one end is set to remain within the first guide hole 26.

Inside the rocker shaft 6 is a partition wall 31 extending in the axial direction.
are press-fitted, fixed, or integrally molded, so that two hydraulic supply passages 32 and 33 are provided within the rocker shaft 6, separated by a partition wall 31.

The tenth lever arm 7 is provided with an oil passage 34 that communicates with the hydraulic chamber 29 in the first connection switching means 21. Communication hole 4 that constantly communicates with the supply path 32
0 is punctured. Further, the tenth hook arm 7 is provided with an annular groove 41 surrounding the rocker shaft 6 and an oil passage 42 that communicates the annular groove 41 with the hydraulic chamber 29 in the second connection switching means 22. A communication hole 43 is bored through which the hydraulic pressure supply path 33 communicates with the annular groove 41 . Therefore, the hydraulic chamber 29 of the first connection switching means 21
A hydraulic pressure supply path 32 communicates with the hydraulic pressure chamber 29 of the second connection switching means 22, and a hydraulic pressure supply path 33 communicates with the hydraulic chamber 29 of the second connection switching means 22. Both hydraulic pressure switching means 21 and 22 can be switched independently of each other. can.

Next, the operation of this embodiment will be explained. When the engine is operated at low speed, the first and second connection switching means 21, 22 are operated to the disconnection side, as shown in FIG. That is, when the hydraulic pressure in the hydraulic chamber 29 is released, the stopper 24 is moved toward the tenth lever arm 7 by the spring force of the spring 25.
Piston 23 is retracted until it abuts step 27. In this state, the contact surfaces of the piston 23 and the stopper 24 are at positions corresponding to the sliding surfaces of the first and 20th claw arms 7.8 and the sliding surfaces of the first and 30th claw arms 7.9, and therefore 1st ° 2nd and 30th
The claw arms 7.8.9 are in sliding contact with each other and are capable of relative angular displacement.

In such a disconnected state, the swinging motion of the 10th hook arm 7 does not affect the second and 30th hook arms 8.9 (the 20th hook arm 8 is connected to the first low-speed cam 3). The 30th lug arm 9 swings in response to the sliding contact of the
swings in response to sliding contact with the second low-speed cam 4. Therefore, one intake valve 1a is driven to open and close by the 207th hook arm 8, and the other intake valve 1b is driven to open and close by the 30th hook arm 9. At this time, since the tenth arm 7 is only in sliding contact with the high-speed cam 5 due to the relatively weak spring force of the lifter spring 20, the friction loss in the valve train can be suppressed to a low level.

In this way, when the engine is operating at low speed, one of the intake valves 1
The intake valve a opens and closes with timing and lift amount depending on the shape of the first low-speed cam 3, and the other intake valve 1b opens and closes with timing and lift amount depending on the shape of the second low-speed cam 4. Therefore, a mixture flow velocity suitable for low-speed operation is obtained, and stable combustion is possible, thereby improving the fuel ratio, stable low-speed operation, and preventing non-king. Moreover, since the shapes of the two image velocity cams 3.4 are different, the turbulence of the air-fuel mixture in the combustion chamber is increased, and this also makes it possible to improve the fuel ratio.

When the engine is operating at medium speed, the first connection switching means 21
As shown in FIG. 5, the first and twentieth anchor arms 7.
8 are connected, and the first and 30th hook arms 7.9 remain uncoupled.

That is, by supplying hydraulic pressure from the hydraulic pressure supply path 32 to the hydraulic chamber 29 of the first connection switching means 21, the piston 2
3 fits into the second guide hole 35 while pressing the stopper 24 against the spring force of the spring 25, and the stopper 24 is pressed against the regulating step 36.

In this state, the first and twentieth hook arms 7.8 are prevented from relative rotation and swing integrally.

Therefore, one intake valve 1a opens and closes at a timing and lift amount that corresponds to the shape of the high-speed cam 5, and the other intake valve 1b opens and closes at a timing and lift amount that corresponds to the shape of the second low-speed cam 4. do. As a result, relatively high charging efficiency can be obtained due to the air-fuel mixture flow speed corresponding to medium-speed operation, and the turbulence of the air-fuel mixture in the combustion chamber is increased in the same way as during low-speed operation, thereby improving the fuel ratio. .

When the engine is operated at high speed, the second connection switching means 22 connects the first and 307th column arms 7.9 as shown in FIG. That is, by supplying hydraulic pressure from the hydraulic pressure supply path 33 to the hydraulic chamber 29 of the second connection switching means 22, the first and 30th lever arms 7.9 are connected. At this time, the connected state of the first and twentieth hook arms 7.8 by the first connection switching means 21 is maintained, and therefore all the rocker arms 7 to 9 are swung by the high speed cam 5. As a result, both intake valves 1a and lb open and close with timing and lift amount according to the shape of the high-speed cam 5,
High output and high torque can be obtained by improving filling efficiency.

In this way, the inside of the rocker shaft 6 is partitioned by the partition wall 31 extending in the axial direction to form hydraulic pressure supply passages 32.33, and these hydraulic pressure supply passages 32.33 are connected to the hydraulic chambers 29 of both connection switching means 21.22. By communicating with each of the two, hydraulic pressure can be supplied from one direction in the axial direction of the rocker shaft 6.
The hydraulic pressure supply circuit is also simple in a valve train for a multi-cylinder internal combustion engine.

As a modification of this first embodiment, when the engine is operated at medium speed,
The first and 30th hook arms 7.9 may be connected while the first and 20th hook arms 7.8 are disconnected. In this way, one intake valve 1a is connected to the first low speed The intake valve 1b opens and closes at a timing and lift amount that corresponds to the shape of the high-speed cam 3, and the other intake valve 1b opens and closes at a timing and lift amount that corresponds to the shape of the high-speed cam 5. can be played.

FIG. 7 shows a second embodiment of the present invention, in which a piston 23' is slidably connected to the second and 30th lever arms 8.9, and a stopper 24 is slidably connected to the tenth lever arm 7, respectively. 24 to piston 2
A spring 25 biasing toward the 3' side is provided, respectively. In addition, oil passages 34.42 are provided in the second and 30th hook arms 8.9, which allow the hydraulic chambers 29 of both connection switching means 21', 22' to communicate with the oil pressure supply passages 32, 33.

In this way, by providing the hydraulic chambers 29 in the second and 30th lever arms 8.9, in addition to the effects of the first embodiment, it is possible to have the effect of preventing malfunctions due to hydraulic leakage.

FIG. 8 shows a third embodiment of the present invention, in which a first connection switching means 2 is connected between the first and twentieth gear arms 7 and 8.
1, and a second connection switching means 22' is provided between the first and thirtieth hook arms 7.9.

This third embodiment can also provide the same effects as the second embodiment.

FIG. 9 shows a fourth embodiment of the present invention. In place of the first and second low-speed cams 3 and 4 in the first embodiment, perfectly circular raised portions 65 and 65 are installed on the camshaft 2. is provided integrally with the

By adopting such a configuration for some cylinders of a multi-cylinder internal combustion engine, for example, at low speeds both intake valves la and lb are deactivated and some of the cylinders are deactivated, which greatly improves the fuel ratio, while at medium speeds, one intake valve is deactivated. It is possible to increase output at medium speeds by operating only 1a, and to obtain high output by operating both intake valves 1a and 1b at high speeds.

FIG. 10 shows a fifth embodiment of the present invention, and shows a second embodiment of the present invention.
and the 30th lever arms 8' and 9' are hydraulic tappets) T
1. They respectively abut on the intake valves 1a and lb via T2. In addition, a partition wall 45 extending in the axial direction and having an rYJ-shaped cross section is press-fitted, fixed, or integrally molded into the rocker shaft 6, and this partition wall 45 allows three hydraulic supply paths 46, 47 to be formed in the rocker shaft 6. .48 are spaced apart.

2nd and 30th hook arms 8' 9. ' is an oil passage 49 for supplying hydraulic pressure to each hydraulic tappet TI and T2.
A communication hole 50 is formed in the rocker shaft 6 to allow each oil passage 49 to communicate with the hydraulic pressure supply oil passage 46 . Further, a rocker arm (not shown) between the second and 307th arm 8' and 9' has a rocker shaft 6 at a position corresponding to both connection switching means 21 and 22.
An annular groove 51.52 surrounding the coupling switching means 21.22 is provided, and oil passages 55, 56 are provided which individually communicate the hydraulic chambers of the two coupling switching means 21.22 with these annular grooves 51.52.

Furthermore, a communication hole 53 that communicates the hydraulic pressure supply passage 47 with the annular groove 51 and a communication hole 54 that communicates the hydraulic pressure supply passage 48 with the annular groove 52 are bored in the rocker shaft 6 .

According to this fifth embodiment, each hydraulic tappet TI.

Hydraulic pressure can be individually supplied to T2, the connection switching means 21, and the connection switching means 22, and the hydraulic pressure supply circuit does not become complicated.

Further, FIG. 11 shows a sixth embodiment of the present invention, in which a partition wall 60 extending in the axial direction and having an rXJ-shaped cross section is press-fitted, fixed, or integrally molded into the rocker shaft 6. Four hydraulic supply passages 46.47° and 48.59° are separated within the rocker shaft 60 by the partition wall 60. The hydraulic pressure supply passages 46, 47 and 48 are hydraulic tapos (TI) as in the fifth embodiment.

T2, which leads to the hydraulic chamber of the connection switching means 21,22. Further, the hydraulic pressure supply path 59 is connected to the cam slipper surface oil supply path 58 and the cam journal oil supply path (Fig. (not shown).

According to this sixth embodiment, in addition to the effects of the fifth embodiment,
Each cam3. 4. 5 and the rocker arms 7.8', 9' and the cam journal can be realized with a simple oil passage configuration.

Although the above embodiments have been described in relation to a pair of intake valves 1a and 1b, the present invention can also be implemented in relation to a pair of exhaust valves, and the cylinder body can be It is also possible to switch and control the stop and variable pulp timing in a multi-stage manner without being limited to the control manner and the number of valves.

C0 Effects of the Invention As described above, according to the present invention, connection switching means capable of switching connection and disconnection between mutually adjacent rocker arms operate independently of each other in accordance with the action of hydraulic pressure. Therefore, the engine operating range can be subdivided into three or more to perform valve control, and it is possible to improve the engine output and the fuel ratio.

In addition, a plurality of hydraulic pressure supply passages individually communicating with each of the connection switching means are installed in the rocker shaft and are separated from each other via partition walls extending in the axial direction, so that the hydraulic pressure supply circuit can be simplified even in a multi-cylinder internal combustion engine. can be converted into

[Brief explanation of drawings]

1 to 6 show a first embodiment of the present invention, FIG. 1 is a vertical side view and a sectional view taken along the line 1-1 in FIG. 3 is a sectional view taken along line mm in FIG. 2, FIG. 4 is a sectional view taken along line 1'/-IV in FIG. FIG. 6 is a sectional view corresponding to FIG. 4 when the 20th rocker arm is connected, FIG. 6 is a sectional view corresponding to FIG. 4 when all rocker arms are connected, and FIGS.
FIG. 9 is a plan view of the fourth embodiment of the present invention, and FIG. 10 is a sectional view corresponding to FIG. 4 of the third embodiment.
FIG. 11 is a vertical side view of the sixth embodiment of the present invention. la, lb...Intake valve, 6...Rocker shaft, 7
゜8.8', 9.9'...Rocker arm, 21.
21', 22.22'... connection switching means, 31, 4
5゜60...Partition wall, 32, 33, 46, 47.48.
59... Hydraulic supply path

Claims (1)

[Claims] In a valve train for an internal combustion engine, a plurality of rocker arms are pivotally supported on a rocker shaft to open and close intake valves or exhaust valves in response to the rotational movement of a camshaft that is rotationally driven in synchronization with the rotation of the engine. Between the rocker arms adjacent to each other, connection switching means capable of switching between connection and disconnection are provided, respectively, so as to operate independently of each other according to the action of hydraulic pressure, and within the rocker shaft,
A valve operating system for an internal combustion engine, characterized in that a plurality of hydraulic supply passages individually communicating with each of the connection switching means are separated from each other via a partition wall extending in the axial direction.