JPH0318002B2 - - Google Patents

Description

Detailed Description of the Invention A. Object of the Invention (1) Industrial Field of Application The present invention is characterized in that a cam is integrated into a camshaft that is rotationally driven in synchronization with the rotation of an engine, and a valve driving member is connected to the cam. The present invention relates to a valve operating system for an internal combustion engine that opens and closes a pair of intake valves or exhaust valves in conjunction with each other.

(2) Prior art In such a multi-cylinder internal combustion engine, the valve diameter and valve lift amount are set at high speed so that the horsepower does not decrease due to inflow resistance when the amount of air-fuel mixture necessary to output the maximum horsepower is taken in. It is common to set this as a priority.

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 in which part of the intake valve or exhaust valve is closed and paused 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. 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 an internal combustion engine that improves engine output and reduces fuel consumption by performing valve train control in three regions: low speed, medium speed, and high speed. The purpose is to provide a valve train.

B. Structure of the Invention (1) Means for Solving Problems According to the present invention, the camshaft includes a low-speed cam, a high-speed cam, and a perfectly circular raised portion corresponding to the base circle of these cams. a first valve driving member that is in sliding contact with the raised portion and connected to one of the intake valves or the exhaust valve; and a first valve driving member that is in sliding contact with the low-speed cam or the high-speed cam and is connected to the other intake valve or exhaust valve. A second valve drive member that is connected to the high speed cam or a third valve drive member that is in sliding contact with the high speed cam or the low speed cam are arranged adjacent to each other. Connection switching means capable of switching between the two are provided so as to be able to operate independently of each other.

(2) Operation When the connection between each valve drive member is released, one intake valve or exhaust valve is closed and rests, and the other intake valve or exhaust valve is opened and closed by the low-speed cam or the high-speed cam. Furthermore, when one of the connection switching means is connected and operated, both intake valves or exhaust valves are opened and closed by a low-speed cam, or one intake valve or exhaust valve is opened and closed by a low-speed cam, and the other intake valve or exhaust valve is opened and closed by a low-speed cam. The valve can be opened and closed using a high-speed cam. Furthermore, when all valve drive members are connected simultaneously, both intake valves or exhaust valves are opened and closed by high-speed cams. Therefore, depending on the combination of the connection states of the respective valve drive members, valve operation control of both intake valves or exhaust valves is performed according to low speed, medium speed, and high speed operation of the engine.

(3) Embodiment Hereinafter, embodiments of the present invention will be explained with reference to the drawings. First, in FIGS. 1 and 2 showing an embodiment of the present invention, a pair of intake valves 1a and 1b are installed in the engine body of an internal combustion engine. are arranged, and these intake valves 1a and 1b are rotated by 1/2 in synchronization with the rotation of the engine.
A raised part 3, a low-speed cam 4, and a high-speed cam 5 are integrally provided on the camshaft 2, which is driven at a rotation ratio of The first, second, and third rocker arms 7, 8, and 9 act as three-valve drive members to open and close the valve.

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 between the intake valves 1a and 1b. 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. Further, the low speed cam 4 has a high portion 4a projecting radially outward from the base circle 4b.
The high-speed cam 5 has a high-position portion 5a which protrudes outward in the radial direction from the base circle 5b to be larger than the high-position portion 4a and extends over a wider center angle range than the high-position 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. The first rocker arm 7 extends above the intake valve 1b, and a tappet screw 13 that can come into contact with the upper end of the intake valve 1b is screwed into the tip of the first rocker arm 7 so that it can move forward and backward. The second rocker arm 8 extends above the intake valve 1a, and a tappet screw 12 that can come into contact with the upper end of the intake valve 1a is screwed onto its tip.

On the other hand, the upper part of the intake valves 1a and 1b has a flange 14,
15, and valve springs 16, 17 surrounding the intake valves 1a, 1b are interposed between the flanges 14, 15 and the engine body. This valve spring 1
6 and 17, the intake valves 1a and 1b are urged 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 third rocker arm 9 as a pressing means.
The lifter 19 is in contact with a lifter spring 2 with a relatively weak spring force interposed between the lifter 19 and the engine body.
0 biases it upward. As a result, the cam slipper 9a of the third rocker arm 9 comes into resilient sliding contact with the high-speed cam 5.

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. The first and third rocker arms 7 and 9 are also in sliding contact with each other, allowing relative angular displacement between the two rocker arms 7 and 9.
A second connection switching means 22 is provided between the first and third rocker arms 7 and 9, which is capable of switching the state in which the two rocker arms 9 are integrally connected.

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 guide hole 35 . A regulating step 3 is provided on the closed end side of the second guide hole 35.
A small diameter portion 37 is provided through the hole 6, 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. Furthermore, 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, the operation of this embodiment will be explained. When the engine is operated at low speed, the first and second connection switching means 21 and 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 first rocker arm 7 by the spring force of the spring 25, and the piston 23 is retreated until it comes into contact with 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 rocker arms 7, 8, and 9 do not affect each other, and the first rocker arm 7 does not swing because the raised portion 3 is perfectly circular. As a result, the intake valve 1b remains closed and at rest. On the other hand, since the second rocker arm 8 is swung by the low-speed cam 4, the intake valve 1a opens and closes at a timing and lift amount depending on the shape of the low-speed cam 4. At this time, since the third rocker arm 9 is in sliding contact with the high-speed cam 5 by the relatively weak spring force of the lifter spring 20, friction loss in the valve train can be suppressed to a low level.

In this way, when the engine is operating at low speed, the intake valve 1b is stopped and only the intake valve 1a is operated by the low speed cam 4.
It opens and closes by. This makes it possible to relatively increase the turbulence of the air-fuel mixture in the combustion chamber, improve the toughness against a decrease in the air-fuel mixture concentration, and reduce fuel consumption.

When the engine is operating at medium 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, both intake valves 1a and 1b are driven to open and close at a timing and lift amount corresponding to the shape of the low-speed cam 4, and an optimum air-fuel mixture inflow speed can be obtained, thereby reducing fuel consumption.

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, 8 remain connected.

Therefore, both intake valves 1a and 1b are driven to open and close at the timing and lift amount defined by the high-speed cam 5, and high output and high torque can be obtained by improving intake efficiency.

FIG. 7 shows a modified example of the switching mode during medium-speed operation. During medium-speed operation, the second connection switching means 22 switches the first and third rocker arms 7,
9 are connected. In this way, by the swinging of the second rocker arm 8, the intake valve 1a opens and closes with the timing and lift amount according to the low-speed cam 4, whereas the intake valve 1b operates with the timing and lift amount according to the high-speed cam 5. The air-fuel mixture is opened and closed in such a manner that turbulence is likely to occur in the air-fuel mixture within the combustion chamber, thereby reducing fuel consumption.

FIG. 8 shows another 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 one intake air The other intake valve 1b is brought into contact with the second rocker arm 8 which is in sliding contact with the high-speed cam 5, and the third rocker arm 9 is brought into sliding contact with the low-speed cam 4.

Moreover, between the third and first rocker arms 9 and 7,
Furthermore, connection and disconnection between the third and second rocker arms 9 and 8 can be switched independently of each other. That is, the connection switching means (not shown) corresponding to the first connection switching means 21 in the embodiments of FIGS. 1 to 7 are connected to the third and first rocker arms 9,
A connection switching means (not shown) provided between the third and second rocker arms 9 and corresponding to the second connection switching means 22 in the embodiments of FIGS. 1 to 7 is provided between the third and second rocker arms 9,
It is set up between 8 rooms.

In this embodiment, when the engine is operating at low speed, one of the intake valves 1a is stopped by disconnecting the third and first rocker arms 9, 7 and between the third and second rocker arms 9, 8. At the same time, the other intake valve 1b opens and closes at a timing and lift amount depending on the shape of the high-speed cam 5. In addition, during medium-speed operation, by connecting the third and first rocker arms 9, 7 and disconnecting the third and first rocker arms 9, 7, one intake valve 1a is connected to the low-speed cam. 4. The other intake valve 1b opens and closes at a timing and lift amount depending on the shape of the high-speed cam 5. Furthermore, during high-speed operation, by connecting the third and first rocker arms 9 and 7 and the third and second rocker arms 9 and 8, the intake valves 1a and 1b adjust to the shape of the high-speed cam 5. It opens and closes at the correct timing and lift amount.

FIG. 9 shows still another embodiment of the present invention, in which a low-speed cam 4 and a high-speed cam 5 are arranged on both sides of the protrusion 3, and one side is disposed on the first rocker arm 7 that is in sliding contact with the protrusion 3. A second rocker arm 8 is brought into contact with the intake valve 1a and slides on the high-speed cam 5.
The other intake valve 1b is brought into contact with the third rocker arm 9, and the third rocker arm 9 is brought into sliding contact with the low speed cam 4.

Although the above embodiment has been described in relation to the intake valves 1a and 1b, the present invention can also be implemented in relation to a pair of exhaust valves.

C. Effects of the Invention As described above, according to the present invention, the camshaft is provided with a low-speed cam, a high-speed cam, and a perfectly circular raised portion corresponding to the base circle of these cams, and the raised portion a first valve drive member that is in sliding contact with the intake valve or the exhaust valve, and a second valve that is in sliding contact with the low-speed cam or the high-speed cam and connected to the other intake valve or exhaust valve; The driving member and the third valve driving member slidingly in contact with the high-speed cam or the low-speed cam are arranged adjacent to each other, and the connection and disconnection of the mutually adjacent valve driving members can be switched independently, so that the connection state thereof can be changed. By combining these, it is possible to obtain an air-fuel mixture inflow speed suitable for low-speed, medium-speed, and high-speed operation, and it is possible to reduce fuel consumption at low and medium speeds and increase output at high speeds. Moreover, during low-speed operation, the intake valve or exhaust valve connected to the first valve driving member is stopped,
By increasing the turbulence of the air-fuel mixture within the combustion chamber, it is possible to reduce fuel consumption.

[Brief explanation of the drawing]

1 to 7 show one embodiment of the present invention, and FIG. 1 is a longitudinal side view, and I of FIG.
-I sectional view, Fig. 2 is a plan view of Fig. 1, Fig. 3 is a -I sectional view of Fig. 2, and Fig. 4 is a sectional view taken along Fig. 1 - line when each rocker arm is disconnected. , FIG. 5 is a sectional view corresponding to FIG. 4 when the first and second rocker arms are connected, and FIG. 6 is a cross-sectional view of the fourth rocker arm when the first and third rocker arms are connected.
7 is a sectional view corresponding to FIG. 5 showing a modification of the switching mode during medium speed operation, and FIGS. 8 and 9 show other embodiments of the present invention, respectively. FIG. 3 is a plan view corresponding to FIG. 2; 1a, 1b...Intake valve, 2...Camshaft,
3...Protuberance, 4...Low speed cam, 4b, 5b...
... Base circle, 5 ... High-speed cam, 7 ... First rocker arm as a first valve drive member, 8 ... Second rocker arm as a second valve drive member, 9 ... Third rocker arm
Third rocker arm as a valve drive member, 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, and is interlocked with the cam via a valve drive member to open and close a pair of intake valves or exhaust valves. In the valve train for an internal combustion engine, the camshaft is provided with a low-speed cam, a high-speed cam, and a perfectly circular raised portion corresponding to the base circle of these cams, and the raised portion a first valve drive member that slides in contact with the intake valve or the exhaust valve and is connected to one of the intake valves or the exhaust valve; and a second valve drive member that slides in contact with the low-speed cam or the high-speed cam and is connected to the other intake valve or exhaust valve. The member and a third valve drive member that slides into contact with the high speed cam or the low speed cam are arranged adjacent to each other, and a connection switching means is provided between the mutually adjacent valve drive members that can switch between connection and disconnection between the two. , a valve train for an internal combustion engine, characterized in that they are each provided so as to be able to operate independently of each other. 2. The internal combustion engine according to claim 1, wherein the third valve driving member is brought into contact with a pressing means for elastically biasing the high-speed cam or the low-speed cam. valve train.