JPH0312205B2 - - Google Patents

Description

[Detailed Description of the Invention] A. Purpose of the Invention (1) Industrial Field of Application The present invention is directed to integrating a pair of intake valves or exhaust valves provided in the engine body with a camshaft that rotates according to the operating state of the engine. The present invention relates to a valve operating system for an internal combustion engine in which the cam is interlocked with a plurality of valve drive members to open and close the valve.

(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 both intake valves or exhaust valves are 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. However, if the valve train is controlled by dividing the operating range more finely, It will be possible to improve engine output and reduce fuel consumption.

The present invention has been made in view of the above circumstances, and provides an internal combustion engine in which valve train control is performed in three regions: low speed, medium speed, and high speed to improve engine output and reduce fuel consumption. The purpose of this invention 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 slidingly in contact with the high-speed cam; a second valve driving member slidingly contacting the low-speed cam and connected to one of the intake valves or the exhaust valve; A third valve drive member that is in sliding contact and is connected to the other intake valve or exhaust valve is arranged adjacent to the third valve drive member, and a connection switch is provided between the mutually adjacent valve drive members that can switch between connection and disconnection between the two. The means are each provided in such a way that they can each operate independently of each other.

(2) Function When the engine is operating at low speed, the valve drive members are disconnected from each other, one of the intake valves or the exhaust valve is closed and rests, and the other is operated at a timing and lift amount according to the low speed cam. Opens and closes. In addition, when the engine is operating at medium speed, one of the coupling switching means is operated in a coupled manner, so that one of the intake valves or exhaust valves remains closed and the other is switched at a timing and lift amount according to the high-speed cam. It can be opened and closed. Further, when the engine is operating at high speed, all valve drive members are connected, and both the intake valve and the exhaust valve are opened and closed at timing and lift amount according to the high speed cam.

(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 protrusion 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 It is driven to open and close by working with the three rocker arms 7, 8, and 9.

The camshaft 2 is rotatably disposed above the engine body, and the high-speed cam 5 is connected to the intake valves 1a and 1.
It is integrally provided on the camshaft 2 at a position corresponding to the middle of b. Further, the low-speed cam 4 and the raised portion 3 are integrally provided on the camshaft 2 on both sides of the high-speed cam 5. Furthermore, 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. Also, low speed cam 4
has a high portion 4a projecting radially outward from the base circle 4b, and the high speed cam 5 has a high portion 4a protruding radially outward from the base circle 4b.
The amount of radial outward protrusion from the high portion 4a
It has a high part 5a which is larger than the above and covers a wider center angle range than the high part 4a.

The rocker shaft 6 is fixedly arranged below the camshaft 2. This rocker shaft 6 includes a first rocker arm 7 as a first valve driving member corresponding to the high speed cam 5 and a second rocker arm 8 as a second valve driving member corresponding to the low speed cam 4.
and a third rocker arm 9 serving as a third valve driving member corresponding to the protrusion 3 are pivoted adjacent to each other, and the upper part of each rocker arm 7, 8, 9 is provided with both cams 4, 5 and the protrusion 3. Cam slippers 7a, 8a, and 9a that come into sliding contact are provided. Also the second and third
The rocker arms 8 and 9 extend above the intake valves 1a and 1b, and have intake valves 1a and 1b at their tips.
Tappet screws 12 and 13 that can come into contact with the upper end of b are screwed so that they can move forward and backward.

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. These valve springs 16 and 17 bias the intake valves 1a and 1b 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 first rocker arm 7 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 7a of the first rocker arm 7 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 swinging motion of the first rocker arm 7 does not affect the second and third rocker arms 8 and 9, and the second rocker arm 8 is in sliding contact with the low-speed cam 4. The third rocker arm 9 does not swing because the raised portion 3 is perfectly circular. Therefore, one intake valve 1a is driven to open and close by the second rocker arm 8,
The other intake valve 1b remains closed. At this time, since the first rocker 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, 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 intake valve 1a opens and closes at a timing and lift amount depending on the shape of the low-speed cam 4, and the other intake valve 1b closes and rests. Therefore, an air-fuel mixture inflow speed suitable for low-speed operation can be obtained, and it is possible to improve fuel efficiency and prevent knocking. Moreover, since the other intake valve remains closed, the turbulence of the air-fuel mixture within the combustion chamber is increased, and the toughness against a decrease in the air-fuel mixture concentration is improved, thereby also reducing 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
However, the regulating step portion 36 is pressed. In this state, the first
The second rocker arms 7 and 8 are prevented from relative rotation and swing together.

Therefore, one intake valve 1a opens and closes at a timing and lift amount depending on the shape of the high-speed cam 5, and the other intake valve 1b remains closed and at rest. As a result, it is possible to obtain an air-fuel mixture inflow speed suitable for medium-speed operation, and to increase the turbulence of the air-fuel mixture in the combustion chamber as in the case of low-speed operation, thereby reducing fuel consumption.

When the engine is operated at high speed, the first 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 connection of the first and second rocker arms 7, 8 by the first connection switching means 21 is maintained, so that all the rocker arms 7,
8 and 9 are oscillated by the high speed cam 5. As a result, both intake valves 1a and 1b open and close at timing and lift amount depending on the shape of the high-speed cam 5, and high output and high torque can be obtained by improving intake efficiency.

FIG. 7 shows another 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 the second and second cams abut against the intake valves 1a and 1b, respectively. 3 rocker arms 8 and 9 are in sliding contact with the low speed cam 4 and the raised portion 3, respectively,
The first rocker arm 7 is in sliding contact with the high-speed cam 5.

In this embodiment as well, the locker arms 7, 8, and 9 are disconnected during low-speed engine operation, the first and second locker arms 7 and 8 are connected during medium-speed operation, and the second and second locker arms are connected during high-speed operation. 3
By connecting the rocker arms 8 and 9, the same functions and effects as in the above embodiment can be obtained.

Although the above embodiment has 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.

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 protrusion, and the first valve driving member slidingly contacts the high-speed cam; a second valve driving member that is in sliding contact with the low-speed cam and connected to one of the intake valves or the exhaust valve; and a third valve driving member that is in sliding contact with the protrusion and connected to the other intake valve or exhaust valve. are arranged adjacent to each other, and the connection and disconnection of the adjacent valve drive members can be independently switched, so that a mixture inflow speed suitable for low, medium and high speeds can be obtained, and at low and medium speeds. It is possible to reduce fuel consumption and increase output at high speeds. Moreover, at low and medium speeds, the intake valve or exhaust valve corresponding to the third valve drive member is deactivated, thereby increasing the turbulence of the air-fuel mixture in the combustion chamber, thereby contributing to a reduction in fuel consumption.

[Brief explanation of drawings]

1 to 6 show an embodiment of the present invention, in which FIG. 1 is a longitudinal side view and a sectional view taken along the line - in FIG. 2, FIG. 2 is a plan view of FIG. 1, Figure 3 is a cross-sectional view taken along the line - - in Figure 2, Figure 4 is a cross-sectional view taken along the line - Figure 1 when each rocker arm is disconnected, and Figure 5 is a cross-sectional view taken when the first and second rocker arms are connected. 4 is a cross-sectional view corresponding to FIG. 4, FIG. 6 is a cross-sectional view corresponding to FIG. 4 when the first, second, and third rocker arms are connected, and FIG. 7 is a second view of another embodiment of the present invention. FIG. 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 pair of intake valves or exhaust valves provided in the engine body are interlocked with a cam integrated with a camshaft that rotates depending on the operating state of the engine via a plurality of valve drive members. In a valve train for an internal combustion engine that opens and closes a valve, the camshaft is provided with a low-speed cam, a high-speed cam, and a perfectly circular protuberance corresponding to the base circles of these cams. , a first valve driving member in sliding contact with the high-speed cam, a second valve driving member in sliding contact with the low-speed cam and connected to one of the intake valves or the exhaust valve, and a second valve driving member in sliding contact with the protrusion and the other. and a third valve driving member connected to the intake valve or the exhaust valve are arranged adjacent to each other, and between the mutually adjacent valve driving members, a connection switching means capable of switching connection and disconnection between the two is provided. 1. A valve train for an internal combustion engine, characterized in that the valve train is provided so as to be able to operate independently of each other. 2. The valve train for an internal combustion engine according to claim 1, wherein the first valve driving member is brought into contact with a pressing means for elastically biasing the high speed cam.