JPS62121810A - Tappet valve device for internal combustion engine - Google Patents

Abstract

PURPOSE:To perform valve on-off operation control inclusive of valve nonoperation, by installing three pieces of suction-exhaust valve driving cams connectedly on a camshaft, and setting one of them down to a valve nonoperating cam, while controlling the joining of rocker arms conformed to each cam. CONSTITUTION:Two suction valves 1a and 1b are opening or closed by rocker arms 7, 9 and 9 to be operated by three cams 3, 5 and 4 connected onto the camshaft 2 set up in the upper part. The cam 3 should be set down to such a nonoperating cam that has no protuberance. A connecting piston 23 is installed in the central rocker arm 7 and an adjacent part of these rocker arms 8 and 9 at both sides, and when pressure oil is fed to a piston chamber 29, the piston 23is pressed against a spring 25 and both are coupled together, and a valve is driven by a wide zone releasing cam at the center. When the cam 3 operates, the suction-exhaust valve 1b comes to nonoperation and is not opened, so that high-speed suction and exhaust are made performable.

Description

Detailed Description of the Invention A1 Object of the Invention (1) Industrial Application Field The present invention provides a camshaft that is rotatably driven in synchronization with the rotation of an engine, and a cam that corresponds to a pair of intake valves or exhaust valves. The present invention relates to a valve operating system for an internal combustion engine in which a rocker arm for opening and closing the intake valve or the exhaust valve is pivotally supported on the camshaft in response to the rotational movement of the cam.

(2) Conventional technology In such a valve train, the valve diameter and valve lift amount are focused on 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 sucked in. 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 a low speed range to a high speed range, the amount of intake air will differ depending on each rotational speed, so the speed of the air mixture flowing into the combustion chamber will differ. In other words, at low speeds, the air-fuel mixture flow speed decreases, reducing the turbulence of the air-fuel mixture in the combustion chamber.
The combustion rate also slows down. For this reason, fuel consumption increases due to a decrease in combustion efficiency, and the non-king limit is forced to decrease 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 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 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.

B0 Structure of the Invention (1) Means for Solving the Problems According to the present invention, the camshaft includes a low-speed cam, a high-speed cam, and a perfect circular protuberance corresponding to the base circle of these cams. The rocker shaft is provided with a tenth rocker arm that slides on the high-speed cam, a second rocker arm that slides on the low-speed cam and abuts one of the intake valves or the exhaust valve, and a second rocker arm that slides on the protrusion. A third rocker arm that contacts and abuts the other intake valve or exhaust valve is 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. They are respectively provided so that they can be operated.

(2) Effect When the engine is operating at low speed, the rocker arms are disconnected from each other, one of the intake valves or the exhaust valve is closed and rests, and the other opens and closes at the timing and lift ffi according to the low speed cam. Operate. In addition, when the engine is operating at medium speed, one of the connection switching means is activated to connect.
One of a pair of intake valves or exhaust valves can be left closed and at rest, and the other can be opened and closed at a timing and lift amount that corresponds to the high-speed cam. Furthermore, when the engine is operating at high speed, all four arms are connected.
A pair of intake valves or exhaust valves are both opened and closed at timing and lift l corresponding to the high-speed cam.

(3) Examples Examples of the present invention will be explained below with reference to the drawings.
First, in FIGS. 1 and 2 showing one embodiment of the present invention, a pair of intake valves 1a and lb are arranged in the engine body of an internal combustion engine, and these intake valves 1a and lb are arranged in the engine body of an internal combustion engine. The camshaft 2 is driven at a rotation ratio of 〃 in synchronization with the rotation.
a raised portion 3, a low-speed cam 4, a high-speed cam 5, and a first. 2nd and 3rd rocker arms? ,
8.9 and is driven to open and close.

The camshaft 2 is rotatably disposed above the engine body, and the high-speed cam 5 is integrally provided on the camshaft 2 at a position corresponding to the middle of the intake valves 1a and 1b. 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 50. Moreover, the raised portion 3 is the base circle 4b of the low-speed cam 4 and the high-speed cam 5,
It is formed into a perfect circle shape corresponding to 5b. Also, low speed cam 4
is a high portion 4 that protrudes radially outward from the base circle 4b.
The high-speed cam 5 has a high-speed cam 5 that projects outward in the radial direction from the base circle 5b to be larger than the high-position portion 4a, and has a high-position portion 5a that extends over a wider center angle range than the high-position portion 4a. have

The rocker shaft 6 is fixedly arranged below the camshaft 2. This rocker shaft 6 has a high-speed cam 5.
A first rocker arm 7 corresponding to the low-speed cam 4, a second rocker arm 8 corresponding to the low-speed cam 4, and a third rocker arm 9 corresponding to the protrusion 3 are pivotally supported. , 8.9
Cam slippers 7a, 8a, and 9a are provided on the upper part of the cams 4, 5 and the raised portion 3 in sliding contact with each other. Also second. The third rocker arm 8.9 extends above the intake valves 1a, 1b, and a tappet screw 12.13 that can come into contact with the upper end of the intake valves 1a, 1b is screwed into the tip of the third rocker arm 8.9 so as to be able to 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 first rocker arm 7,
A bottomed cylindrical glue lid 19 is brought into contact as a pressing means, and this lick 19 is interposed between the engine body and urged upward by a lid spring 20. 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, and can be switched between a state in which relative angular displacement thereof is possible and a state in which the double-ended rocker arms 7.8 are integrally connected. A possible first connection switching means 21 connects the first and second
It is provided between rocker arms 7 and 8. The first and third rocker arms 7.9 are also in sliding contact with each other, and the first and third rocker arms 7.9 can be switched between a state in which relative angular displacement thereof is possible and a state in which the double-ended rocker arms 7.9 are integrally connected. A two-way switching means 22 is provided between the first and third rocker 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 second rocker arms 7.8 are connected and a position where the connection is released, and a stopper 24 that restricts movement of the piston 23. A spring 2 that biases the stopper 24 to move the piston 23 toward the disconnection position.
5.

The first rocker arm 7 has a first guide hole 26 opened toward the second rocker arm 8 side and parallel to the rocker shaft 6, and the closed end side of the first guide hole 26 has a step. A small diameter portion 28 is provided via the 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 tenth hook arm 7 has an oil passage 3 communicating with the hydraulic chamber 29.
0 is bored in the rocker shaft 6, and an oil passage 31 communicating with a hydraulic pressure supply source (not shown) is bored in the rocker shaft 6. Furthermore, both sleeve passages 30 and 31 are always in communication through a communication hole 32 formed in the side wall of the rocker shaft 6, regardless of the swinging state of the first rocker arm 7.

A second guide hole 35 opened toward the first rocker arm 7 side is bored in the 20V rocker arm 8 in correspondence with the first guide hole 26. The 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;
Further, an insertion hole 38 coaxial with the small diameter portion 37 is bored in 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 axial length of the piston 23 is such that when one end thereof contacts the step 27, the other end is located between the first and second rocker arms 7.8, and the stopper 24 is placed in the restriction 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.

Oil passage 3 in the first and second connection switching means 21.22
1 are separated from each other by a steel ball 33 that is press-fitted and fixed into the rocker shaft 6, so that the first and second connection switching means 21 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 2122 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
The piston 23 is moved toward the first rocker arm 7 by the force of the spring 5, and the piston 23 is retreated until it abuts against the stepped portion 27.

In this state, the contact surfaces of the piston 23 and the stopper 240 are at positions corresponding to the sliding surfaces of the first and second rocker arms 7.8 and the sliding surfaces of the first and third rocker arms 7.9. 1. The second and third rocker 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 first rocker arm 7 does not affect the second and third rocker arms 8.9, and the second rocker arm 8 is in sliding contact with the low-speed cam 4. The 30th hook 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, and 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 lid 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 of the intake valves 1
The intake valve a opens and closes at a timing and lift ffi according to the shape of the low-speed cam 4, and the other intake valve 1b closes and rests. Therefore, it is possible to obtain a mixture flow velocity suitable for low-speed operation, thereby improving fuel efficiency and preventing knocking. Moreover, since the other intake valve remains closed, the turbulence of the air-fuel mixture within the combustion chamber is increased, thereby improving the toughness against a drop in the air-fuel mixture concentration, thereby also reducing fuel consumption.

When the engine is operating at medium speed, the first connection switching means 21
As shown in FIG. 5, first and second rocker arms 7.
8 are coupled, and the first and third rocker arms 7.9 remain uncoupled.

That is, by supplying hydraulic pressure to the hydraulic chamber 29 of the first connection switching means 21, the piston 23 presses the stopper 24 against the spring force of the spring 25 and moves into the second guide hole 3.
5, and the bar 24 is pressed against the regulating stepped portion 36. In this state, the first and second rocker arms 7.8 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. As a result, it is possible to obtain a mixture flow rate suitable for medium-speed operation, and to reduce fuel consumption by increasing the turbulence of the mixture in the combustion chamber as in the case of low-speed operation.

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, by supplying hydraulic pressure to the hydraulic chamber 29 of the second connection switching means 22, the first and third
0 Connect the hook arm 7.9. At this time, the disconnection of the first and 207th rocker arms 7.8 by the first connection switching means 21 is continued, and therefore all the rocker arms 7.
8.9 is oscillated by the high speed cam 5. As a result,
Both intake valves 1a, lb are opened and closed 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 second and second cams abut against the intake valves 1a and lb, respectively. 3
The rocker arm 8.9 is in sliding contact with the low-speed cam 4 and the raised portion 3, respectively, and the first rocker arm 7 is in sliding contact with the high-speed cam 5.

In this embodiment as well, each rocker arm 7, 8, 9 is disconnected when the engine is running at low speed, and the first rocker arm is disconnected when the engine is running at medium speed.
By connecting the second rocker arms 7 and 8, and further connecting the second and third rocker arms 8 and 9 during high-speed operation, the same functions and effects as in the embodiment described above 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.

C0 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 rocker shaft is provided with a first rocker arm that slides into contact with the high-speed cam. , a second rocker arm that abuts one intake valve or exhaust valve and slides on the low-speed cam, and a third rocker arm that abuts the other intake valve or exhaust valve and slides on the protrusion, and are adjacent to each other. Since the connection and disconnection between the rocker arms can be switched independently, a mixture airflow speed suitable for low, medium and high speeds can be obtained, reducing fuel consumption at low and medium speeds and increasing output at high speeds. can be achieved. Moreover, at low and medium speeds, the intake valve or exhaust valve corresponding to the third rocker arm is deactivated, which increases the turbulence of the air-fuel mixture in the combustion chamber, contributing to a reduction in fuel consumption.

[Brief explanation of drawings]

1 to 6 show an embodiment of the present invention,
FIG. 1 is a longitudinal side view, and a sectional view taken along the line I-1 in FIG.
Fig. 2 is a plan view of Fig. 1, Fig. 3 is a sectional view taken along line mm in Fig. 2, Fig. 4 is a sectional view taken along line IV-IV of Fig. 1 when each rocker arm is disconnected, and Fig. Figure 5 shows the 1st and 20th
A cross-sectional view corresponding to FIG. 4 when the seven arms are connected,
FIG. 6 is a sectional view corresponding to FIG. 4 when the first, second, and thirtieth hook arms are connected, and FIG. 7 is a plan view corresponding to FIG. 2 of another embodiment of the present invention. la, Ib...Intake valve, 2...Camshaft, 3...
... Protruding portion, 4... Low speed cam, 4b, 5b... Base circle, 5... High speed cam, 6... Rocker shaft, 7... 107th arm, 8... No. 2 rocker arm, 9... third rocker arm, 19... glue lid as pressing means, 21.22... connection switching means

Claims (2)

[Claims] (1) A cam corresponding to a pair of intake valves or exhaust valves is integrated into a camshaft that is rotationally driven in synchronization with the rotation of the engine, and a rocker shaft is provided with a cam that corresponds to a pair of intake valves or an exhaust valve. In a valve train for an internal combustion engine in which a rocker arm for opening and closing a valve or an exhaust valve is pivotally supported, the camshaft includes a low-speed cam, a high-speed cam, and a straight line corresponding to the base circle of these cams. The rocker shaft is provided with a first rocker arm that slides on the high-speed cam, and a second rocker arm that slides on the low-speed cam and abuts one of the intake valves or the exhaust valve. A third rocker arm that slides on the protuberance and abuts on the other intake valve or the exhaust valve is pivotally supported, and a connection switching means is provided between the mutually adjacent rocker arms 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 operation of an internal combustion engine according to claim (1), characterized in that the first rocker arm is brought into contact with a pressing means for elastically biasing the high-speed cam. Valve device.