JPH10266818A - Variable valve system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide by a simple structure, a variable valve system for an internal combustion engine, by which the lift conditions of an intake valve and an exhaust valve which are driven to be opened and closed in synchronism with a crankshaft, are varied into a low lift condition and a high lift condition. SOLUTION: In this variable valve system for an internal combustion engine, a low lift driving valve mechanism 10a is equipped with a low lift rocker arm 12 which is swung by a low lift cam 11 which is swingably supported by a fixed fulcrum 13a and is driven in synchronism with a crankshaft 21, and a high lift driving valve mechanism 10b is equipped with a high lift rocker arm 15 which is swung by a high lift cam 14 which is swingably supported by a movable fulcrum which can cancels a supporting function and is driven in synchronism with the crankshaft 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve actuation device for an internal combustion engine which can change a lift state of an intake valve, an exhaust valve, etc., which is opened and closed in synchronization with a crankshaft, between a low lift state and a high lift state. About.

[0002]

2. Description of the Related Art As one type of a variable valve operating device for an internal combustion engine, as disclosed in Japanese Patent Application Laid-Open No. 7-286506, a low-lift driving valve mechanism and a high-lift driving valve mechanism are provided, which are synchronized with a crankshaft. 2. Description of the Related Art There is a variable valve actuation device for an internal combustion engine that is capable of changing a lift state of a valve such as an intake valve or an exhaust valve that is driven to open and close between a low lift state and a high lift state.

[0003] The low-lift drive mechanism constituting this variable valve operating device has a drive rocker arm, the high-lift drive mechanism has a free rocker arm, and has a connecting piston slidably fitted in guide holes provided in both rocker arms. Hydraulic means for intermittently connecting the two rocker arms with each other by sliding the connecting piston, and a lost motion mechanism for regulating the movement of the free rocker arm when the free rocker arm is separated from the drive rocker arm. .

In this variable valve operating device, the driving rocker arm is selectively connected to the free rocker arm or released by the sliding operation of the connecting piston, thereby selectively driving the driving rocker arm. In this case, the lift amounts of the intake valve and the exhaust valve are changed to correspond to the operating state of the internal combustion engine.

[0005]

In the above-mentioned conventional variable valve apparatus for an internal combustion engine, a connecting piston for connecting and disconnecting the drive rocker arm and the free rocker arm is indispensable, and the connecting piston is connected to both rocker arms. Are inserted into the guide holes, the mass of the movable portions of both rocker arms increases, which is disadvantageous in operation. In addition, it is necessary to ensure high dimensional accuracy between the guide hole of each rocker arm and the connecting piston, and the assemblability of the variable valve operating device becomes a problem.

[0006] Further, in the variable valve actuating device, a driving means for sliding the connecting piston is required, and a lost means for restricting the movement of the free rocker arm when the free rocker arm is separated from the drive rocker arm. Although it has a motion mechanism, the lost motion mechanism is configured independently and is mounted on the cylinder head, so that the number of parts constituting the variable valve operating device is increased and the cost is increased. Become. Therefore,
An object of the present invention is to address each of the above problems.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a variable valve operating device for an internal combustion engine, and more particularly to a lift state of a valve which is provided with a low lift drive valve mechanism and a high lift drive valve mechanism and is opened and closed in synchronization with a crankshaft. Is applied to a variable valve train of an internal combustion engine of a type that can be changed between a low lift state and a high lift state.

According to the present invention, there is provided a variable valve apparatus for an internal combustion engine of the type described above, wherein the low-lift drive valve mechanism is swingably supported at a fixed fulcrum and driven in synchronization with the crankshaft. A low-lift rocker arm that is swung by a high lift cam that is swingably supported at a movable fulcrum capable of disabling a support function and is driven in synchronization with the crankshaft. A high lift rocker arm.

In the variable valve operating apparatus for an internal combustion engine according to the present invention, the movable fulcrum supporting the high lift rocker arm is constituted by a hydraulic lifter, and the hydraulic lifter is constituted to have a lost motion function. It is preferable that the operation point of the high lift rocker arm is located on the cam side from the contact point of the low lift rocker arm with respect to the valve on the low lift rocker arm.

[0010]

In the variable valve train for an internal combustion engine according to the present invention, the low lift drive valve mechanism and the high lift drive valve mechanism are selectively operated in accordance with the operation state of the internal combustion engine, thereby enabling the internal combustion engine to operate. Change the lift state of the intake valve, exhaust valve and other valves to a low lift state and a high lift state to improve the output of the internal combustion engine, reduce fuel consumption,
The purpose is to improve the idling characteristics.

Thus, in order to operate the low lift drive valve mechanism, the function of supporting the movable fulcrum supporting the high lift rocker arm of the high lift drive valve mechanism is invalidated. Accordingly, the low lift rocker arm of the low lift drive valve mechanism is driven to open and close by the drive of the low lift cam driven in synchronization with the crankshaft, and each valve opens and closes. In this case, the opening / closing operation of the high lift rocker arm with respect to the valve is invalidated.

On the other hand, to switch the driving of the low lift drive valve mechanism to the high lift drive valve mechanism, the function of supporting the movable fulcrum supporting the high lift rocker arm is restored. Thus, the high lift rocker arm is driven by the high lift cam driven in synchronization with the crankshaft.
Open / close operation is performed prior to the low lift rocker arm to open / close each valve.

By the way, in the variable valve operating device,
In order to switch the drive of the low lift drive valve mechanism and the drive of the high lift drive valve mechanism, the function of supporting the movable fulcrum that supports the high lift rocker arm constituting the high lift drive valve mechanism may be invalidated. As the invalidating means, a lost motion function may be provided to a hydraulic lifter provided on a cylinder head of the internal combustion engine and supporting the high lift rocker arm. Therefore, the configuration of the variable valve apparatus can be simplified, the number of parts can be reduced, and the assemblability can be improved, and the cost can be reduced.

Further, in the variable valve operating device, since a large-mass member is never attached to or attached to each rocker arm, the mass of each rocker arm does not increase, and each rocker arm does not increase. Operationally advantageous. Further, in the variable valve operating device, it is necessary to provide driving means for operating other mechanisms, for example, driving means for operating to slide the connecting pins of both rocker arms as in the above-mentioned conventional variable valve operating device. Therefore, it is possible to further reduce the number of parts, improve the assemblability, and reduce the cost.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 shows an example of a variable valve apparatus for an internal combustion engine according to the present invention. The variable valve device is a valve device that opens and closes a pair of intake valves, and includes a low lift drive valve mechanism 10a, a high lift drive valve mechanism 10b, and a hydraulic lifter 1 that constitutes a high lift drive valve mechanism 10b.
0c. In addition, the variable valve apparatus can be applied as a variable valve apparatus that opens and closes an exhaust valve without changing the configuration.

As shown in FIGS. 1 to 5, the low lift drive valve mechanism 10a includes a low lift cam 11 and a low lift rocker arm 12 formed integrally with a cam shaft 21. In the low-lift rocker arm 12, the arm body 12a has a substantially T-shape in plan view, and an arc-shaped recess 12b that opens downward and forms a supported portion is formed at the base end of the arm body 12a. Yes,
A pair of adjustment screws 12c and 12d are screwed to both ends on the swing end side. The low lift rocker arm 12 is supported at the base end of the arm main body 12 a on the top of a fixed support column 13 erected on the cylinder head 22.

The fixed column 13 has a support portion 1 having a hemispherical top.
3a. Low lift rocker arm 12
Is an arc-shaped recess 12b on the base end side of the arm body 12a.
Is supported by being fitted to the support portion 13a of the fixed support column 13, and the lower portion of the low lift cam 11 is moved downward by each intake valve 23a,
23b, each adjusting screw 12c, 1
The lower end of 2d is in contact with the top of each intake valve 23a, 23b. In this state, the low lift cam 11 is in contact with the arm body 12a of the low lift rocker arm 12.

Each of the intake valves 23a and 23b opens and closes an intake hole 22a provided in the cylinder head 22. When the intake valves 23a and 23b are inserted into the mounting holes 22b of the cylinder head 22, they are urged by a valve spring 24, and Adjust screw 12c, 12d of lift rocker arm 12
Resiliently. Low lift drive valve mechanism 10a
In the above, the low lift rocker arm 12 swings up and down with the support portion 13a at the top of the fixed column 13 as a fulcrum by the action of the low lift cam 11 that rotates integrally with the crankshaft 21 to move the intake valves 23a and 23b up and down. To open and close the intake hole 22a.

The high-lift drive valve device 10b includes a high-lift cam 14, a high-lift rocker arm 15, and a hydraulic lifter 10c formed integrally with a cam shaft 21, as shown in FIGS. . In the high lift rocker arm 15, the arm body 15
a has a substantially I-shaped plane, and a base end portion of the arm body 15a is formed with an arc-shaped concave portion 15b which opens downward and forms a supported portion. A projection 15c protruding downward is formed. The high lift rocker arm 15 is supported at the base end of the arm body 15a on the top of the movable support 16 of the hydraulic lifter 10c disposed on the cylinder head 22.

The movable column 16 has a top portion of a column main body 16a formed on a hemispherical support portion 16b. The high lift rocker arm 15 has an arc-shaped recess 15b on the base end side of the arm main body 15a. Of the low lift rocker arm 12 extending between the high lift cam 14 and the low lift rocker arm 12 toward the intake valves 23a and 23b.
In contact with the upper surface of the swing end of the arm body 12a. The contact portions of the protrusions 15c of the high lift rocker arm 14 with the low lift rocker arm 12 are determined by the intake valves 23a, 23b of the low lift rocker arm 12.
Are located on the side of the high lift cam 14 from the contact point.

In the high-lift drive valve mechanism 10b, the high-lift rocker arm 15 swings up and down with the support 16b at the top of the movable support 16 as a fulcrum by the action of the high-lift cam 14 which rotates integrally with the crankshaft 21. By swinging the rocker arm 12, each intake valve 23 a, 2 is connected via the low-lift rocker arm 12.
3b is moved up and down to open and close the intake hole 22a. The top of the cam surface of the high lift cam 14 is formed to be larger in diameter than the top of the cam surface of the low lift cam 11, and the amount of pushing of the high lift rocker arm 15 against the low lift rocker arm 12 is small.
Is set to be larger than the pushing amount with respect to.

As shown in FIGS. 6 and 8, the hydraulic lifter 10c includes a movable column 16, a casing 17 which is press-fitted into a mounting hole 22c of a cylinder head 22, and slidably supports the movable column 16, and a cylinder head 22. Mounting hole 2
2c, the plunger 18 is slidably inserted into a mounting hole 22d provided substantially orthogonal to the mounting hole 2c, a check ball 19a, and a spring 19 for urging the check ball 19a.
b, a spring 19c for urging the movable support 16 and a spring 19d for urging the plunger 18.

In the hydraulic lifter 10c, the movable support 1
6 is urged by a spring 19c to move upward, a pressure chamber R1 is formed between the movable column 16 and the casing 17, and a reservoir chamber R2 is formed on the outer periphery of the casing 17. In the communication passage P between these two chambers R1 and R2,
The check ball 19a is housed therein, and the check ball 19a is resiliently seated on the valve seat 19e by the urging force of the spring 19b to close the communication path P. The oil pressure is supplied into the pressure chamber R1 from a supply hole 22e provided in the cylinder head 22.

In the hydraulic lifter 10c, a mounting hole 22d is formed in the cylinder, and the plunger 18
The rear end of the plunger 18 is formed in the hydraulic oil chamber R3, and the plunger 18 is moved to the hydraulic oil chamber R3 by a spring 19d interposed at the distal end. The plunger 18 is provided with an operating rod 18a at the tip end thereof, penetrates the reservoir chamber R2, and checks the check ball 19 against the spring 19b.
a. The supply and discharge of the hydraulic oil into and from the hydraulic oil chamber R3 is performed by a supply and discharge hole 22f provided in the cylinder head 22.

In the hydraulic lifter 10c, under normal conditions, hydraulic oil is supplied to the hydraulic oil chamber R3, and the plunger 18 is in the forward position as shown in FIG. The pressure chamber R1 and the reservoir chamber R2 communicate with each other by being separated from the sheet 19e.
For this reason, the hydraulic pressure in the pressure chamber R1 can flow into the reservoir chamber R2, and the function of supporting the movable column 16 with respect to the high lift rocker arm 15 is invalidated.

In this state, when the hydraulic oil in the hydraulic oil chamber R3 is discharged, the plunger 18 retreats as shown in FIG. 8 to seat the check ball 19a on the valve seat 19e, and the pressure chamber R1 and the reservoir chamber R2 Cuts off communication with the As a result, the movable column 16 is moved upward by the oil pressure in the pressure chamber R1 and held at the same position, and the function of supporting the high lift rocker arm 15 is restored.

In the variable valve operating device having such a configuration, the low-lift drive valve mechanism 10 is controlled in accordance with the operating state of the internal combustion engine.
a and the high-lift drive valve mechanism 10b are selectively operated to change the lift state of the intake valve and the exhaust valve of the internal combustion engine between a low-lift state and a high-lift state, thereby improving the output of the internal combustion engine, reducing fuel consumption, The idling characteristics can be improved.

However, the above-described variable valve operating device operates the low-lift drive valve mechanism 10 in the early stage of driving the internal combustion engine.
a, and switches to the high-lift drive mechanism 10b to operate the drive mechanism 10b in accordance with an increase in the number of revolutions of the internal combustion engine and an increase in the load. Under normal conditions, the hydraulic oil chamber R3 of the hydraulic lifter 10c has In a state where the hydraulic oil is supplied, the plunger 18 is at the forward position as shown in FIG. 6, the check ball 19a is separated from the valve seat 19e, and connects the pressure chamber R1 and the reservoir chamber R2. Therefore, the pressure oil in the pressure chamber R1 can flow into the reservoir chamber R2, and the function of supporting the movable column 16 with respect to the high lift rocker arm 15 is invalidated.

In the variable valve operating apparatus in such a state, the low lift cam 11 rotating integrally with the crankshaft 21 repeatedly pushes the low lift rocker arm 12 to move the low lift rocker arm 12 as shown in FIG. The support valve 13a is swung about the fulcrum, and the intake valves 23a and 23b are repeatedly opened and closed. In this case, the high-lift cam 14 rotating integrally with the crankshaft 21 repeatedly pushes the high-lift rocker arm 15, but the high-lift rocker arm 15 has its protruding portion 15c as a support point as shown by a broken line in FIG. Performs a swinging motion of pushing down against the spring 19c, and does not participate in the opening / closing operation for each of the intake bubbles 23a and 23b. Therefore, each intake valve 23a, 2
The lift amount 3b is the low lift amount set by the low lift rocker arm 12.

In this state, when the hydraulic oil in the hydraulic oil chamber R3 of the hydraulic lifter 10c is discharged, the plunger 18 retreats as shown in FIG. 8 to seat the check ball 19a on the valve seat 19e, and the pressure chamber R1 And reservoir room R2
Cuts off communication with the Thereby, the movable column 16 is moved upward by the pressure oil in the pressure chamber R1 and held at the same position,
The support function for the high lift rocker arm 15 is restored.

In the variable valve operating apparatus in this state, the low lift cam 1 rotating integrally with the crankshaft 21
1 repeatedly pushes and swings the low lift rocker arm 12, but the high lift cam 12 rotating integrally with the crankshaft 21 repeatedly pushes the high lift rocker arm 15 to support the support 16 b of the movable support 16. As shown in FIG.
As shown in (1), the low-lift rocker arm 12 is pushed to swing, and the intake valves 23a and 23b are repeatedly opened and closed via the low-lift rocker arm 12. Therefore, the lift amount of each of the intake valves 23a and 23b is the high lift amount set by the high lift rocker arm 15.

It should be noted that the variable valve device is naturally applied as a variable valve device for an exhaust valve, and the low-lift drive valve mechanism 10a and the high-lift drive valve mechanism 10b are selected according to the operation state of the internal combustion engine. , The lift state of the intake valve and the exhaust valve of the internal combustion engine is changed between a low lift state and a high lift state, thereby improving the output of the internal combustion engine, reducing fuel consumption, and improving the idling characteristics. .

By the way, in the variable valve operating device,
Low lift drive valve mechanism 10a and high lift drive valve mechanism 1
0b, the high-lift drive valve mechanism 1
0b, the support function of the movable column 16 that supports the high lift rocker arm 15 may be invalidated. As the invalidation means, the hydraulic lifter 10c provided on the cylinder head 22 of the internal combustion engine and supporting the high lift rocker arm 15 may be used. Since the lost motion function only needs to be provided, the configuration of the variable valve apparatus can be simplified, and the number of parts and the assemblability can be reduced, and the cost can be reduced. be able to.

Further, in the variable valve operating device, since a large-mass member is not attached to or mounted on each of the rocker arms 12, 15, the mass of each of the rocker arms 12, 15 may increase. This is advantageous for the operation of each rocker arm 12, 15.

[Brief description of the drawings]

FIG. 1 is a front view showing an example of a variable valve apparatus according to the present invention.

FIG. 2 is a plan view of the variable valve operating device.

FIG. 3 is a partial side view of the variable valve operating device as viewed from the direction of arrow 3 in FIG. 2;

FIG. 4 is a partially broken side view showing a low-lift drive valve mechanism constituting the variable valve apparatus.

FIG. 5 is a partially cutaway side view showing a high-lift drive valve mechanism constituting the variable valve apparatus.

FIG. 6 is a vertical sectional view of an operating state showing a hydraulic lifter constituting the variable valve operating device.

FIG. 7 is a partially broken front view showing an operation state of the low-lift drive valve mechanism.

FIG. 8 is a longitudinal sectional view of a non-operating state showing a hydraulic lifter constituting the variable valve operating device.

FIG. 9 is a partially broken front view showing an operation state of the high lift drive valve mechanism.

[Explanation of symbols]

10a: Low lift drive valve mechanism, 10b: High lift drive valve mechanism, 10c: Hydraulic lifter, 11: Low lift cam, 12: Low lift rocker arm, 13: Fixed support,
14 ... High lift cam, 15 ... High lift rocker arm, 16 ... Movable column, 17 ... Casing, 18 ... Plunger, 21 ... Crank shaft, 22 ... Cylinder head

Claims (3)

[Claims] A variable valve actuation device for an internal combustion engine, comprising a low lift drive valve mechanism and a high lift drive valve mechanism, wherein a lift state of a valve that is opened and closed in synchronization with a crankshaft can be changed between a low lift state and a high lift state. The low-lift drive valve mechanism includes a low-lift rocker arm that is swingably supported at a fixed fulcrum and is swung by a low-lift cam that is driven in synchronization with the crankshaft; and the high-lift drive valve mechanism has a support function. A variable valve train for an internal combustion engine, comprising: a high lift rocker arm that is swingably supported by a movable fulcrum that can be disabled and is swung by a high lift cam that is driven in synchronization with the crankshaft. 2. The variable valve apparatus for an internal combustion engine according to claim 1, wherein the movable fulcrum supporting the high lift rocker arm is constituted by a hydraulic lifter, and the hydraulic lifter has a lost motion function. A variable valve train for an internal combustion engine, comprising: 3. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein an action point of the high lift rocker arm is located on the low lift rocker arm from a contact point of the low lift rocker arm with respect to the valve. A variable valve operating device for an internal combustion engine, wherein the variable valve operating device is located on a side of the engine.