JPH0252082B2 - - Google Patents

Description

[Detailed Description of the Invention] A. Purpose of the Invention (1) Industrial Field of Application The present invention is aimed at opening and closing an intake valve or an exhaust valve in response to a camshaft that is rotationally driven in synchronization with the rotation of an engine. A plurality of three or more cam followers are arranged adjacent to each other, and between each adjacent cam follower, there is a connecting member movable between a connecting position and a disconnecting position of each cam follower, and a hydraulic pressure is applied to the connecting member. and a return spring for applying a spring force counteracting the hydraulic pressure to the connecting member, each of which has a hydraulic pressure chamber, and a hydraulic pressure supply path connected to the internal combustion chamber. Concerning engine valve train.

(2) Prior Art Conventionally, in such a valve operating system, the set load of the return spring of each coupling switching means is set to be the same, and hydraulic pressure is individually supplied to the hydraulic chamber of each coupling switching means.

(3) Problems to be solved by the invention However, in the above-mentioned conventional system, it is necessary to provide a hydraulic pressure supply path individually corresponding to the hydraulic chamber of each connection switching means. 61−
179088) (Japanese Unexamined Patent Publication No. 62-121809), for example, a steel ball is press-fitted and fixed into a locking shaft that pivotally supports a locking arm as a cam follower, and the inside of the locking shaft is divided into two on both sides of the steel ball. Therefore, the hydraulic pressure supply circuit becomes complicated.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a valve operating system for an internal combustion engine that can simplify the hydraulic pressure supply circuit.

B. Structure of the Invention (1) Means for Solving Problems According to the present invention, the set loads of the return springs of each connection switching means are set to be different from each other, and the hydraulic pressure supply path is connected to the hydraulic chamber of each connection switching means. communicated in common with
A hydraulic pressure supply means capable of switching and supplying multiple stages of hydraulic pressure is connected to the hydraulic pressure supply path.

(2) Effect By switching and supplying multiple stages of hydraulic pressure from the hydraulic pressure supply means, each connection switching means can be selectively operated, and therefore the hydraulic pressure supply path can be configured to correspond to each connection switching means. No separation is required, simplifying the hydraulic supply circuit.

(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, the engine body of an internal combustion engine has a pair of intake valves 1a, 1b is arranged, and these intake valves 1a, 1b are 1/1 in synchronization with the rotation of the engine.
A first low-speed cam 3, a high-speed cam 5, and a second low-speed cam 3' that are integrally provided on a camshaft 2 driven at a rotation ratio of 2, and a cam follower that is pivotally supported on a rocker shaft 6 that is parallel to the camshaft 2. the first, second and third rocker arms 7,
It is driven to open and close by working with 8 and 9.

The camshaft 2 is rotatably disposed above the engine body, and the high-speed cam 5 is connected to both intake valves 1a,
The first and second low-speed cams 3 and 3' are integrally provided on the camshaft 2 at positions corresponding to the cams 1b and 1b. The first low-speed cam 3 has a shape suitable for low-speed operation of the engine, and has a high portion 3a that protrudes outward in a relatively small amount along the radial direction of the camshaft 2. 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 that of the high-position portion 3a of the first low-speed cam 3. It has a high portion 5a that spans a wider center angle range than 3a. Furthermore, the second low-speed cam 3' also has a shape suitable for low-speed operation of the engine, and has a high-position portion 3' whose outward protrusion amount along the radial direction of the camshaft 2 is smaller than that of the high-position portion 3a.
It has a.

The rocker shaft 6 is fixedly arranged below the camshaft 2. This rocker shaft 6 includes a first rocker arm 7 corresponding to the first low speed cam 3, a second rocker arm 8 corresponding to the high speed cam 5, and a third rocker arm 9 corresponding to the second low speed cam 3'. , are pivotally supported adjacent to each other in the axial direction, and on the upper part of each claw arm 7, 8, 9 is a cam slipper 7 that is in sliding contact with each cam 3, 5, 3', respectively.
a, 8a, and 9a are provided. Further, the first and third rocker arms 7, 9 extend above the intake valves 1a, 1b, and have the intake valves 1a, 1b at their tips.
Tappet screws 12, 13 that can come into contact with the upper end of 1b
are screwed together so that they can move forward and backward.

On the other hand, a retainer 1 is installed above the intake valves 1a and 1b.
4, 15 are provided, and this retainer 14,
Between 15 and the engine body, there is a valve spring 1 that biases the intake valves 1a and 1b upward, that is, in the valve closing direction.
6 and 17 are interposed.

In FIG. 3, a bottomed cylindrical lifter 19 is in contact with the lower surface of the end of the second rocker arm 8, and this lifter 19 is a lifter with a relatively weak spring force interposed between it and the engine body. It is urged upward by a spring 20. As a result, the cam slipper 8a of the second rocker arm 8 is always elastically brought into sliding contact with the high-speed cam 5.

In FIG. 4, there are two states between the first and second rocker arms 7 and 8 that are adjacent to each other: a state in which relative angular displacement of these two rocker arms 7 and 8 is possible, and a state in which both rocker arms 7 and 8 are integrally connected. A first connection switching means 21a is provided which can switch between the mutually adjacent second and third rocker arms 8 and 9. A second connection switching means 21b is provided which can switch between a state in which the two parts 9 are integrally connected.

The first and second connection switching means 21a and 21b basically have the same configuration.Hereinafter, the configuration of the first connection switching unit 21a will be explained in detail with the subscript a, and Switching means 21
b is only shown with the suffix b and its detailed explanation will be omitted.

The first connection switching means 21a includes a piston 23a as a connection member that is movable between a position where the first and second rocker arms 7 and 8 are connected and a position where the connection state is released, and the movement of the piston 23a is restricted. The stopper 24a and the piston 23
Stopper 24a to move a to the uncoupling side.
and a return spring 25a that urges the.

The second locking arm 8 has a first locking arm 7.
A first guide hole 26a with a bottom that opens toward the side and is parallel to the rock shaft 6 is bored, and a small diameter portion 28a is provided at the closed end side of the first guide hole 26a via a stepped portion 27a. It will be done. 1st
A piston 23a is slid into the guide hole 26a, and the piston 23a and the first guide hole 26a
A hydraulic chamber 29a is defined between the two.

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

The axial length of the piston 23a is such that when one end of the piston 23a comes into contact with the stepped portion 27a, the other end of the piston 23a is
It is set so that it is located between the locker arms 7 and 8, and one end remains in the first guide hole 26a when the stopper 24a enters the second guide hole 35a until it comes into contact with the regulating step 36a. There is.

The second rocker arm 8 is provided with an oil passage 34a that communicates with the hydraulic chamber 29a. A communication hole 40a communicating with 32 is bored.

In this first connection switching means 21a, the return spring 2
The first and second rocker arms 7 and 8 are connected by the piston 23a by supplying the hydraulic pressure sufficient to overcome the spring force of the piston 5a and move the piston 23a from the hydraulic pressure supply path 32 to the hydraulic chamber 29a.

In the second connection switching means 21b, the return spring 25b
The hydraulic pressure sufficient to overcome the spring force and move the piston 23b is supplied from the hydraulic pressure supply path 32 to the hydraulic chamber 29.
b, the second and third rocker arms 8, 9 are connected by the piston 23b.

The set loads of the return springs 25a, 25b in the first and second connection switching means 21a, 21b are set to be different from each other. For example, the set load of the return spring 25a is set smaller than the set load of the return spring 25b.

A hydraulic pressure supply means 45 is connected to the hydraulic pressure supply path 32 . This hydraulic pressure supply means 45 is a hydraulic pressure supply source 4
6, regulators 47 and 48 connected in parallel to the hydraulic pressure supply source 46 via a switching valve 52, a mode in which the hydraulic pressure from these regulators 47 and 48 is switched and supplied to the hydraulic pressure supply path 32, and a mode in which the hydraulic pressure is supplied to the hydraulic pressure supply path 32.
A control valve 49 that can switch the manner in which the hydraulic pressure of No. 2 is released.
Equipped with. Furthermore, check valves 50 and 51 are interposed between the regulators 47 and 48 and the control valve 49, respectively.

One regulator 47 controls and outputs the hydraulic pressure from the hydraulic pressure supply source 46 to a relatively low hydraulic pressure P1, and this hydraulic pressure P1 is returned when it is supplied to the hydraulic chamber 29a of the first connection switching means 21a. Although the hydraulic pressure is exerted to overcome the spring force of the spring 25a and move the piston 23a, the return spring 2 is exerted in the hydraulic chamber 29b of the second connection switching means 21b.
The hydraulic pressure is set to be smaller than the spring force of 5b. The other regulator 48 controls and outputs the oil pressure from the oil pressure supply source 46 to a relatively high oil pressure P2, and when this oil pressure P2 is supplied to the oil pressure chambers 29a and 29b, it returns to the spring 2.
The pistons 23a and 23a resist the spring force of 5a and 25b.
It is determined to exert hydraulic pressure to move 23b.

Next, the operation of this embodiment will be explained. When the engine is operated at low speed, the control valve 49 releases the hydraulic pressure in the hydraulic pressure supply path 32, that is, the hydraulic chambers 29a and 29b. Therefore, in the first and second connection switching means 21a, 21b, the pistons 23a, 23b are returned to the hydraulic chambers 29a, 29b by the return springs 25a, 25b.
It is pushed to the side and is in a disconnected state. Therefore, the first, second and third rocker arms 7,
8 and 9 are in a state in which the pistons 23a, 23b and stoppers 24a, 24b are brought into sliding contact with each other so that they can swing relative to each other.

Such first and second connection switching means 21
a, 21b are in the disconnected state, the first rocker arm 7 swings in sliding contact with the first low-speed cam 3 due to the rotational movement of the camshaft 2, and the third rocker arm 9 swings in response to the sliding contact with the first low-speed cam 3. It swings in response to sliding contact with the cam 3'. At this time, the second rocker arm 8 swings in response to sliding contact with the high-speed cam 5, but the swinging action has no effect on the operations of the first and third rocker arms 7, 9.

In this manner, when the engine is operating at low speed, one intake valve 1a opens and closes at a timing and lift amount that corresponds to the shape of the first low-speed cam 3, and the other intake valve 1b operates to open and close the second low-speed cam 3'. It opens and closes with timing and lift amount depending on the shape. Therefore, an air-fuel mixture inflow speed suitable for low-speed operation can be obtained, and stable combustion can be achieved, so that it is possible to improve the fuel ratio, stabilize low-speed operation, and prevent knocking. Moreover, since the shapes of the low-speed cams 3, 3' are different, the turbulence of the air-fuel mixture in the combustion chamber 9 is increased, and this also makes it possible to improve the fuel ratio.

When the engine is operating at medium speed, a relatively low oil pressure P1 is supplied from the oil pressure supply means 45 to the oil pressure chambers 29a, 29b. As a result, the first connection switching means 21a
Then, the piston 23a moves toward the first rocker arm 7 against the spring force of the return spring 25a, and the piston 23a moves the first and second rocker arms 7, 8.
are concatenated. As a result, the first and second rocker arms 7 and 8 are driven to swing by the high-speed cam 5. On the other hand, the second connection switching means 21b
In this case, the movement of the piston 23b is prevented by the return spring 25b, and the connection between the second and third rocker arms 8, 9 remains disconnected.

Therefore, when the engine is operating at medium speed, 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
The opening and closing operations are performed at timing and lift amount depending on the shape of the second low-speed cam 3'.

During high-speed operation of the engine, a relatively high hydraulic pressure P2 is supplied from the hydraulic pressure supply means 45 to both hydraulic chambers 29a, 29b. As a result, the second connection switching means 21
Also at point b, the piston 23b moves toward the third rocker arm 9 against the spring force of the return spring 25b,
The second and third rocker arms 8 and 9 are connected. At this time, the first and second rocker arms 7, 8
Therefore, the first, second, and third rocker arms 7, 8, and 9 are integrally driven to swing by the high-speed cam 5.

Therefore, both intake valves 1a and 1b are opened and closed at timing and lift amount depending on the shape of the high-speed cam 5.

In such a valve train, the hydraulic pressure supply path 32 in the rocker shaft 6 is connected to both connection switching means 21a, 2.
1b, and the hydraulic pressure to be supplied is supplied from one axial direction of the rocker shaft 6, so that the hydraulic pressure supply circuit does not become complicated even in a multi-cylinder internal combustion engine.

FIG. 5 shows a second embodiment of the present invention, and parts corresponding to those of the first embodiment described above are given the same reference numerals.

The pistons 23a, 23b of the first and second connection switching means 60a, 60b are slidably connected to the first and third rocker arms 7, 9, and the stoppers 24a', 24
b' is slidably connected to the second rocker arm 8 and the stoppers 24a', 24.
Return springs 25a and 25b are interposed between b'. Moreover, the second rocker arm 8 includes a stopper 24a',
An air vent hole 53 is provided for smooth movement of 24b'.
a, 53b are drilled. Further, a hydraulic chamber 29a is defined between the first rocker arm 7 and the piston 23a, and a hydraulic chamber 29a is defined between the first rocker arm 7 and the piston 23b.
A hydraulic chamber 29b is defined between them, and a hydraulic pressure supply path 32 is communicated with the hydraulic chambers 29a and 29b.

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

FIG. 6 shows a third embodiment of the present invention, and parts corresponding to each of the above embodiments are given the same reference numerals.

The second rocker arm 8 has a first connection switching means 6.
1a and the second piston 23a are slid together.
The stopper 24b' of the connection switching means 61b is slid together. Further, the stopper 24a' of the first connection switching means 61a is slidably engaged with the first rocker arm 7, and the piston 23b of the second connection switching means 61b is slidably engaged with the third rocker arm 9.

This third embodiment can also provide the same effects as those of the embodiments described above.

FIG. 7 shows a fourth embodiment of the present invention, in which a piston 23a' of a first connection switching means 62a is slid on the first rocker arm 7, and a second connection switching means 62b is fitted on the third rocker arm 9. The piston 23b' is slid together. Further, the second rocker arm 8 is provided with guide holes 64a and 64b, respectively, into which the pistons 23a' and 23b' can slide. 1st
and third rocker arms 7, 9, and each piston 2
Hydraulic chambers 29a and 29b are defined between the hydraulic pressure chambers 3a' and 23b', respectively, and the hydraulic chambers 29a and 29b are commonly communicated with the hydraulic pressure supply path 32. Moreover, each piston 23a', 23b' is integrally connected with a shaft part 63a, 63b which projects outward from the rocker arms 7, 9, and these shaft parts 63a, 6
Return springs 25a, 25b are interposed between the tip of the locker arm 3b and each rocker arm 7, 9.

According to this fourth embodiment, it is possible to achieve the same effects as in each of the above-mentioned embodiments, and also to omit the stopper that was necessary in each of the above-mentioned embodiments.

FIG. 8 shows a fifth embodiment of the present invention, in which a first rocker arm 7 is slidably connected to a medium-speed cam 4, a second rocker arm 8 is slidably connected to a low-speed cam 3, and a third rocker arm 9 is slidably connected to a high-speed cam 4. The single intake valve 1 is interlocked and connected to the second rocker arm 8. Moreover, the first and second rocker arms 7 and 8 and the second and third rocker arms 8 and 9 can be connected and disconnected from each other.

According to this embodiment, during low-speed operation, the connection between each rocker arm 7, 8, and 9 is released and the intake valve 1 is opened and closed by the low-speed cam 3, and during medium-speed operation, the first
The second rocker arms 7 and 8 are connected to open and close the intake valve 1 with the medium-speed cam 4, and during high-speed operation, the rocker arms 7, 8, and 9 are integrally connected to open and close the intake valve 1 with the high-speed cam. It can be opened and closed by pressing 5.

FIG. 9 shows a sixth embodiment of the present invention, in which a first rocker arm 7 is in sliding contact with a low-speed cam 3, and a second rocker arm 8, which is interlocked and connected to a single intake valve 1, is a perfect circle. The third rocker arm 9 is in sliding contact with a raised portion 55 provided on the camshaft 2, and the third rocker arm 9 is in sliding contact with the high-speed cam 5.

This allows the intake valve 1 to be closed and paused when the rocker arms 7, 8, and 9 are disconnected, which is effective when stopping some cylinders of a multi-cylinder internal combustion engine.

In each of the above embodiments, a valve train for driving the intake valves to open and close has been described, but the present invention is also applicable to a valve train for driving the exhaust valves to open and close. Furthermore, it is also possible to provide three coupling switching means between the four cam followers and supplying hydraulic pressure to each coupling switching means in three stages to achieve more precise valve control.

C. Effects of the Invention As described above, according to the present invention, the set loads of the return springs of each connection switching means are set to be different from each other, and the hydraulic pressure supply path is commonly communicated with the hydraulic chamber of each connection switching means. Since a hydraulic pressure supply means that can switch and supply hydraulic pressure in multiple stages is connected to the hydraulic supply path, by switching the hydraulic pressure in multiple stages, each connection switching means can be selectively operated, simplifying the hydraulic supply circuit. can be converted into

[Brief explanation of the drawing]

1 to 4 show a first embodiment of the present invention, and FIG. 1 is a vertical side view, and FIG.
2 is a plan view of FIG. 1, FIG. 3 is a sectional view taken along the - line of FIG. 2, and FIG. 4 is a plan view of FIG.
5, 6 and 7 are sectional views corresponding to FIG. 4 of the second, third and fourth embodiments, and FIGS. 8 and 9 are sectional views corresponding to the fifth and sixth embodiments. FIG. 2 is a plan view corresponding to FIG. 2 of the embodiment. 1, 1a, 1b... Intake valve, 2... Camshaft, 7, 8, 9... Locker arm as cam follower, 21a, 21b, 60a, 60b, 61
a, 61b, 62a, 62b... connection switching means,
23a, 23b, 23a', 23b'...piston as a connecting member, 25a, 25b...return spring,
29a, 29b...hydraulic chamber, 32...hydraulic supply path, 45...hydraulic supply means.

Claims (1)

[Claims] 1 A plurality of cam followers of three or more are arranged adjacent to each other in order to open and close an intake valve or an exhaust valve in response to a camshaft that is rotationally driven in synchronization with the rotation of the engine, and between each adjacent cam follower. includes a connecting member movable between a connecting position and a disconnecting position of each cam follower, a hydraulic chamber for applying hydraulic pressure to the connecting member, and a spring force for applying a spring force to the connecting member in opposition to the hydraulic pressure. In a valve operating system for an internal combustion engine, in which connection switching means each having a return spring are provided, and a hydraulic pressure supply path is connected to each of the hydraulic chambers, the set loads of the return springs of each connection switching means are different from each other. The internal combustion engine is characterized in that the hydraulic pressure supply path is commonly communicated with the hydraulic chambers of the respective connection switching means, and the hydraulic pressure supply path is connected to a hydraulic pressure supply means capable of switching and supplying a plurality of stages of hydraulic pressure. valve train.