JPH0250284B2 - - Google Patents

Description

[Detailed Description of the Invention] A. Purpose of the Invention (1) Industrial Application Field The present invention relates to an intake valve or an exhaust valve disposed for each cylinder on a camshaft that is rotationally driven in synchronization with the rotation of an engine. The present invention relates to a valve operating system for a multi-cylinder internal combustion engine, in which a cam is integrated in accordance with the rotation of the cam, and a rocker arm for opening and closing the intake valve or the exhaust valve is pivotally supported on the rocker shaft.

(2) Prior art In such a valve train, the valve diameter and valve lift amount are set with emphasis on high speed so that when the amount of air-fuel mixture necessary to output maximum horsepower is sucked in, horsepower will not decrease due to inflow resistance. It is common to set the

By the way, if the intake valve is driven with the same valve timing and the same lift amount from low speed range to high speed range, the intake amount will differ depending on each rotation speed, so
The air-fuel mixture inflow speed into the combustion chamber is different. That is, at low speeds, the air-fuel mixture inflow speed decreases, the turbulence of the air-fuel mixture within the combustion chamber becomes small, and the combustion speed also slows down. For this reason, fuel consumption increases due to a decrease in combustion efficiency, and the knocking limit decreases due to a decrease in combustion speed.

Therefore, in order to solve this problem, there is a system developed by Japanese Patent Application Publication No. 2003-110102, in which part of the intake valve or exhaust valve is closed and paused during low-speed operation, and the intake valve or exhaust valve is opened and closed during high-speed operation.
It is disclosed in the 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. It will be possible to improve output and reduce fuel consumption.

The present invention has been made in view of the above circumstances, and provides a valve train for a multi-cylinder internal combustion engine that performs valve train control divided into three speed ranges to improve engine output and reduce fuel consumption. The purpose is to provide

B. Structure of the Invention (1) Means for Solving Problems According to the present invention, the camshaft for a specific cylinder includes a low-speed cam, a high-speed cam, and perfect circles corresponding to the base circles of these cams. The rocker shaft is provided with a first rocker arm that slides on the protrusion and abuts the intake valve or the exhaust valve, a second rocker arm that slides on the low-speed cam, and a second rocker arm that slides on the high-speed cam. The third rocker arm is pivotally supported, and connection switching means capable of switching connection and disconnection between the two adjacent rocker arms are respectively provided so as to be able to operate independently of each other.

(2) Effect When the connection between each rocker arm is released, the first rocker arm that slides in contact with the perfectly circular protrusion does not swing, and the intake valve or exhaust valve remains closed. Furthermore, when the first and second rocker arms are connected with the connection between the first and third rocker arms being released, the first rocker arm swings following the second rocker arm that is in sliding contact with the low-speed cam, and the intake air is The valve or exhaust valve opens and closes at the timing and lift determined by the low-speed cam. Furthermore, when the first and third rocker arms are connected,
The first rocker arm is the third rocker arm that is in sliding contact with the high-speed cam.
It swings following the rocker arm, and the intake valve or exhaust valve opens and closes at the timing and lift amount determined by the high-speed cam.

(3) Embodiments Hereinafter, embodiments of the present invention will be explained with reference to the drawings. First, in FIGS. 1 and 2 showing a first embodiment of the present invention, each cylinder of a multi-cylinder internal combustion engine has a single air intake. The intake valve 1 of a specific cylinder is connected to a camshaft 2 which is driven at a rotation ratio of 1/2 in synchronization with the rotation of the engine.
A raised portion 3, a low-speed cam 4, a high-speed cam 5, and first, second, and third rocker arms 7, 8, and 9 pivotally supported on a rocker shaft 6 parallel to the camshaft 2. It is driven to open and close depending on the action.

Hereinafter, only the configuration of the valve train in a specific cylinder will be described.

The camshaft 2 is rotatably disposed above the engine body, and the raised portion 3 is integrally provided on the camshaft 2 at a position corresponding to the intake valve 1. Further, a low speed cam 4 and a high speed cam 5 are integrally provided on the camshaft 2 on both sides of the raised portion 3. Moreover, the raised portion 3 is formed in a perfect circular shape corresponding to the base circles 4b, 5b of the low-speed cam 4 and the high-speed cam 5. In addition, the low speed cam 4 has a base circle 4b.
It has a high portion 4a that protrudes radially outward from the
The high-speed cam 5 has a high portion 5a which protrudes outward in the radial direction from the base circle 5b to a greater extent than the high portion 4a and spans a wider center angle range than the high portion 4a.

The rocker shaft 6 is fixedly arranged below the camshaft 2. The locking shaft 6 includes a first locking arm 7 corresponding to the raised portion 3;
a second rocker arm 8 corresponding to the low speed cam 4;
A third rocker arm 9 corresponding to the high-speed cam 5 is pivotally supported, and cam slippers 7a, 8a, 9a are provided on the upper part of each rocker arm 7, 8, 9 to make sliding contact with the raised portion 3 and both cams 4, 5. Further, the first rocker arm 7 extends above the intake valve 1, and a tappet screw 12 that can come into contact with the upper end of the intake valve 1 is screwed into the tip of the first rocker arm 7 so as to be able to move forward and backward.

On the other hand, a flange 14 is provided at the top of the intake valve 1, and a valve spring 16 surrounding the intake valve 1 is interposed between the flange 14 and the engine body. This valve spring 16 urges the intake valve 1 upward, that is, in the valve closing direction.

In FIG. 3, a bottomed cylindrical lifter 19 is provided on the lower surface of the end of the second rocker arm 8 as a pressing means.
The lifter 19 is urged upward by a lifter spring 20 interposed between the lifter 19 and the engine main body. As a result, the cam slipper 8a of the second rocker arm 8 comes into resilient sliding contact with the low-speed cam 5. Further, a lifter (not shown) is elastically abutted on the lower surface of the end of the third rocker arm 9.

In FIG. 4, the first and second rocker arms 7, 8 are in sliding contact with each other, allowing relative angular displacement, and both rocker arms 7, 8
A first connection switching means 21 that can switch between a state in which the first and second rocker arms 7 and 8 are integrally connected
provided in between. Further, the first and third rocker arms 7, 9 are also in sliding contact with each other, and both rocker arms 7, 9 are in a state where relative angular displacement thereof is possible.
A second connection switching means 22 that can switch between a state in which the first and third rocker arms 7,
It is located between 9 rooms.

The first and second connection switching means 21 and 22 basically have the same configuration, and will be described below.
Only the configuration of the first connection switching means 21 will be described in detail, and a detailed explanation of the second connection switching means 22 will be omitted.

The first connection switching means 21 includes a piston 23 that is movable between a position where the first and second rocker arms 7 and 8 are connected and a position where the connection is released.
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 first locking arm 7 has a second locking arm 8.
While opening towards the side, the lock shaft 6
A first guide hole 26 parallel to the first guide hole 26 is bored, and a small diameter portion 28 is provided at the closed end side of the first guide hole 26 via a stepped portion 27. First guide hole 26
A piston 23 is slidably engaged with the piston 23 , and a hydraulic chamber 29 is defined between the piston 23 and the closed end of the first guide hole 26 .

An oil passage 30 communicating with the hydraulic chamber 29 is bored in the first rocker arm 7, and an oil passage 31 communicating with a hydraulic pressure supply source (not shown) is bored in the rocker shaft 6. Further, both oil passages 30 and 31 are connected to each other via a communication hole 32 bored in the side wall of the rock shaft 6.
Communication is always maintained regardless of the swinging state of the first rocker arm 7.

The second rocker arm 8 is provided with a second guide hole 35 that is open toward the first rocker arm 7 and corresponds to the first guide hole 26.
A disc-shaped stopper 24 is slid into the hole 35. A small diameter portion 37 is provided at the closed end side of the second guide hole 35 via a regulating step 36, and an insertion hole 38 coaxial with the small diameter portion 37 is bored at the closed end. Moreover, a guide rod 39 coaxially and integrally provided with the stopper 24 is inserted into the insertion hole 38. moreover,
A coiled spring 25 surrounding the guide rod 39 is interposed between the stopper 24 and the closed end of the second guide hole 35 .

The length of the piston 23 in the axial direction is such that when one end comes into contact with the stepped portion 27, the other end is located between the first and second rocker arms 7 and 8, and the stopper 24 is placed against the regulating step 36. The setting is such that one end remains in the first guide hole 26 when the second guide hole 35 is entered until the contact is made.

The oil passages 31 in the first and second connection switching means 21 and 22 are isolated from each other by a steel ball 33 that is press-fitted and fixed into the rocker shaft 6.
1 and 22 can perform switching operations independently of each other.

Next, to explain the operation of this embodiment, when the engine is operating at a very low speed, the first
And the second connection switching means 21, 22 are operated to the connection release side. That is, when the hydraulic pressure in the hydraulic chamber 29 is released, the stopper 24 moves toward the first rocker arm 7 due to the spring force of the spring 25, and the piston 23
is retracted until it abuts against the stepped portion 27. In this state, the contact surfaces of the piston 23 and the stopper 24 are the sliding surfaces of the first and second rocker arms 7, 8, and the first and third rocker arms 7, 9.
Therefore, the first, second, and third rocker arms 7, 8, and 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 second and third rocker arms 8 and 9 does not affect the first rocker arm 7, and the raised portion 3
Since it has a perfect circular shape, the first rocker arm 7 does not swing. At this time, the second and third rocker arms 8, 9 are only in sliding contact with the respective cams 4, 5 due to the relatively weak spring force of the lifter spring 20.
Friction loss in the valve train can be kept low.

In this way, when the engine is operating at extremely low speeds, the intake valve 1 of a specific cylinder remains closed, making it possible to reduce fuel consumption.

When the engine is operating at low speed, the first connection switching means 21
As a result, as shown in FIG. 5, the first and second rocker arms 7, 8 are connected, and the first and third rocker arms 7, 9 remain disconnected.
That is, by supplying hydraulic pressure to the hydraulic chamber 29 of the first connection switching means 21, the piston 23 fits into the second guide hole 35 while pressing the stopper 24 against the spring force of the spring 25, and presses the stopper 24. 24
is pressed against the regulating step portion 36. In this state, the first
The second rocker arms 7 and 8 are prevented from relative rotation and swing together.

Therefore, the intake valve 1 is driven to open and close at a timing and lift amount that corresponds to the shape of the low-speed cam 4, that is, low-speed operation, and the optimum air-fuel mixture inflow speed is obtained, which reduces fuel consumption and prevents knocking. be able to.

When the engine is operated at high speed, the second connection switching means 22 connects the first and third rocker arms 7, 9 as shown in FIG. That is, the second
By supplying hydraulic pressure to the hydraulic chamber 29 of the connection switching means 22, the first and third rocker arms 7, 9
Concatenate. At this time, the first and second rocker arms 7 and 8 may be connected or may be disconnected. In any case, the first rocker arm 7 swings following the third rocker arm 9.

Therefore, the intake valve 1 is driven to open and close at the timing and lift amount specified by the high-speed cam 5,
High output and high torque can be obtained by improving suction efficiency.

FIG. 7 shows a second embodiment of the present invention, in which a pair of intake valves 1a and 1b in a specific cylinder are provided with a first
The rocker arm 7 is brought into contact. This embodiment can also provide the same effects as the above-mentioned embodiments.

FIG. 8 shows a third embodiment of the present invention, in which a protrusion 3 and a high-speed cam 5 are arranged on both sides of a low-speed cam 4, and correspondingly a pair of rocker arms 8 are arranged on both sides of the second rocker arm 8. A first rocker arm 7 and a third rocker arm 9 are in contact with the intake valves 1a and 1b.
and are placed.

FIG. 9 shows a fourth embodiment of the present invention, in which a protrusion 3 and a high-speed cam 5 are arranged on both sides of the low-speed cam 4, and a single rocker arm 8 is correspondingly arranged on both sides of the second rocker arm 8. A first rocker arm 7 that abuts the intake valve 1 and a third rocker arm 9 are arranged.

Although the above embodiments have been described in relation to an intake valve, the present invention can also be implemented in relation to an exhaust valve.

C. Effects of the Invention As described above, according to the present invention, the camshaft for a specific cylinder includes a low speed cam, a high speed cam,
A perfectly circular raised portion corresponding to the base circle of these cams is provided, and the rocker shaft is provided with a first rocker arm that slides on the raised portion and abuts on the intake valve or the exhaust valve, and a first rocker arm that slides on the low speed cam. A second rocker arm in contact with the high-speed cam and a third rocker arm in sliding contact with the high-speed cam are pivotally supported, and between the mutually adjacent rocker arms, connection switching means capable of switching connection and disconnection between the two are provided independently of each other. As the engine is installed at very low speeds, specific cylinders can be deactivated to reduce fuel consumption, and when the engine is operating at very low speeds, the intake valves can be activated at timing and lift amounts that correspond to these conditions. Alternatively, the exhaust valve can be opened and closed.

[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 - in FIG. 2, and FIG. 2 is a plan view of FIG. 1. , 3rd
The figure is a sectional view taken along the line - - of Fig. 2, Fig. 4 is a sectional view taken along the line - Fig. 1 when each rocker arm is disconnected, and Fig. 5 is a 4th view when the first and second rocker arms are connected. 6 is a sectional view corresponding to FIG. 4 when the first and third rocker arms are connected, and FIGS. 7, 8, and 9 are sectional views corresponding to the second and third rocker arms of the present invention. and FIG. 3 is a plan view corresponding to FIG. 2 of the fourth embodiment. 1, 1a, 1b...Intake valve, 2...Camshaft,
3... Protuberance, 4... Low speed cam, 4b, 5b... Base circle, 5... High speed cam, 6... Rock shaft, 7
...First locking arm, 8...Second locking arm, 9
...Third rocker arm, 19...Lifter as pressing means, 21, 22... Connection switching means.

Claims (1)

[Scope of Claims] 1. A cam is integrated into a camshaft that is rotationally driven in synchronization with the rotation of the engine, corresponding to the intake valve or exhaust valve disposed for each cylinder, In a valve operating system for a multi-cylinder internal combustion engine, in which a rocker arm is pivotally supported to open and close the intake valve or exhaust valve according to the rotational operation of The rocker shaft is provided with cams and perfectly circular raised portions corresponding to the base circles of the cams, and the rocker shaft is provided with a first rocker arm that slides on the raised portion and abuts the intake valve or the exhaust valve, and a first rocker arm for low speed operation. A second rocker arm that slides in contact with the cam and a third rocker arm that slides in contact with the high-speed cam are pivotally supported, and between the mutually adjacent rocker arms, a connection switching means that can switch between connection and disconnection between them is installed. 1. A valve train for a multi-cylinder internal combustion engine, characterized in that each valve is provided so as to be able to operate independently. 2. The multi-cylinder internal combustion engine according to claim 1, wherein the second and third rocker arms are each brought into contact with pressing means for resiliently biasing the corresponding cams. valve train. 3. According to claim 1, the intake valves or the exhaust valves are arranged in pairs for each cylinder, and the first rocker arm is brought into contact with the pair of intake valves or exhaust valves in a specific cylinder. valve train for multi-cylinder internal combustion engines.