JPH0648083Y2 - 4-cycle engine valve mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a valve operating mechanism of a 4-cycle engine.

[Conventional technology]

A four-cycle engine having a plurality of valves for performing the same action (for example, intake action) in one cylinder has been conventionally put into practical use.

The plurality of valves in this engine are simultaneously driven by the cam of the valve mechanism, and a predetermined angle range (hereinafter referred to as valve working angle) while the camshaft rotates 360 °
Open with.

[Problems to be solved by the device]

The time during which the valve is open becomes shorter as the engine speed increases.

Therefore, in order to secure a sufficient valve opening operation time even at a high engine speed, it is sufficient to set the valve operating angle wide, that is, the profile of the cam is set so as to obtain a wide valve operating angle. It may be designed, but in this case, the valve opening operation time becomes excessive at low engine speed, which causes inconvenience such as deterioration of fuel consumption.

The above-described conventional valve operating mechanism of the engine has a drawback that it is impossible to obtain a valve operating angle suitable for both high engine speed and low engine speed because the valve operating angle is fixed. Hold.

In view of such a situation, an object of the present invention is to provide a valve operating mechanism of a four-cycle engine capable of obtaining both a valve working angle adapted at a low engine speed and a valve working angle adapted at a high engine speed. Especially.

[Means for Solving the Problems]

The present invention is a valve operating mechanism applied to a four-cycle engine having a plurality of valves that perform the same action in one cylinder, and is rotatably fitted to a camshaft, and at least one of the above valves is used. First and second cams respectively actuating one and at least one of the remaining valves;
And a cam rotation means for rotating the first and second cams from the reference position in different directions by a predetermined angle in cooperation with the operation of the actuator. .

[Action]

According to this valve mechanism, the first and second cams are rotated in different directions, which changes the valve working angle.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a valve operating mechanism according to the present invention applied to drive intake valves 1 and 2 in a 4-valve engine. The figure is a sectional view taken along the line AA of FIG.

In this valve mechanism, cams 4 and 5 are rotatably fitted to the cam shaft 3. These cams 4 and 5 are provided at the portions corresponding to the positions of the valves 1 and 2, respectively, and the inner peripheral surfaces thereof are provided with concave grooves 4a and 5a along the axis of the camshaft 3. ing.

The cams 4, 5 are restricted from moving in the left-right direction by the washer 6 and the C-ring 7.

The camshaft 3 has a sliding hole with its axis as the central axis.
3a is formed in the inside thereof, and the sliders 8 and 9 and the piston 10 as a cam rotation actuator are slidably fitted into the sliding hole 3a.

Further, elongated hole-shaped guide holes 3b and 3c penetrating the peripheral wall of the cam shaft 3 are formed at the positions where the cams 4 and 5 are arranged. The guide holes have the same length.

As shown in FIG. 2, the guide holes 3b and 3c are provided so as to be inclined with respect to the axis of the camshaft 3. That is, the guide hole 3b is formed in a lower right direction and the guide hole 3c is formed in a lower left direction when viewed from the direction of the figure. The right ends of the guide holes 3b and 3c are located on the same plane including the axis of the camshaft 3.

In addition, as shown in FIG. 4 (a) and FIG. 5 (b), which are sectional views of FIG. 1 taken along line BB and CC, as shown in FIG.
3b and 3c are also provided at symmetrical positions about the axis of the camshaft.

Pins 11 and 12 are press-fitted and fixed to the sliders 8 and 9 in a mode orthogonal to the axis of the camshaft 3.

As shown in FIG. 4 (a), one end of the pin 11 is fitted into the groove 4a of the cam 4 through one guide hole 3b, and the other end is fitted into the other guide hole 3b. ing.

Further, as shown in FIG. 5, one end of the pin 12 is fitted into the concave groove 5a of the cam 5 through one guide hole 3c, and the other end thereof is fitted into the other guide hole 3c. There is.

The left end surface of the slider 8 is biased to the right by a spring 13. Therefore, the slider 8 is always the first
The position shown in the figure, that is, the pin 11 is placed at the position where it abuts against the right end of the guide hole 3b.

On the other hand, the urging force of the spring 13 acts on the slider 9 via the slider 8 and the steel ball 14. Therefore, the slider 9 is always placed at the position where the pin 12 abuts the right end of the guide hole 3c.

The tip of the piston 10 is slidable by the leftward urging force of a spring 15 having a smaller spring constant than the spring 13.
It is lightly abutted on the right end surface of.

The operation of the valve mechanism according to this embodiment will be described below.

When the rotational power from the crankshaft (not shown) is transmitted to the camshaft 3, the cams 4 and 5 are transmitted via the pins 11 and 12.
Is rotated integrally with the camshaft 3, and accordingly, the intake valves 1 and 2 are connected to the intake valve ports 16 and 16 shown in FIG.
Open and close 17 respectively.

FIG. 6 (a) shows that when the cams 4 and 5 are in the reference position, that is, as shown in FIGS. 4 (a) and 5 (a), the top ends of the cams 4 and 5 are respectively the cam shaft 3 Lift characteristics a of valves 1 and 2 when they are located on the reference position R of
Is illustrated. The horizontal axis of the graph shown in FIG. 6A is the rotation angle of the camshaft 3.

When hydraulic pressure is applied to the right end surface of the piston 10 shown in FIG. 1, the sliders 8 and 9 are moved leftward by the leftward biasing force of the piston 10, and the pins 11 and 12 are moved accordingly. It is moved along the guide holes 3b and 3c. Then, as shown in FIG. 3, the left rows of the sliders 8 and 9 are stopped at the positions where the pins 11 and 12 contact the left ends of the guide holes 3b and 3c, respectively.

With the movement of the pin 11 along the guide hole 3b, the cam 4
2 is pushed upward by the pin 11 in FIG. 2, and as a result, the cam 4 is rotated with respect to the cam shaft 3 in the arrow direction shown in FIG.

On the other hand, the movement of the pin 12 along the guide hole 3c causes the concave groove 5a of the cam 5 to be pushed downward by the pin 12 in FIG. It is rotated in the direction of the arrow shown in FIG.

4 (b) shows the angle change direction and the amount of angle change Δθ ₁ of the cam 4 when the pin 11 moves from the start end to the end of the guide hole 3b, and FIG. Hole 3
The angle change direction and the angle change amount Δθ ₂ of the cam 5 when moving from the start end to the end of c are shown. As shown in the figure, the cams 4 and 5 are arranged in different directions by a predetermined angle Δ.
It is rotated by θ ₁ and Δθ _2, respectively.

In this embodiment, the inclination of the guide holes 3b and 3c is set so that Δθ ₁ = Δθ ₂ .

FIG. 6B shows the lift characteristics b and c of the valves 1 and 2 when the cams 4 and 5 rotate with respect to the camshaft 3 by the angles Δθ ₁ and Δθ ₂ , respectively.

As shown in the figure, the lift characteristic b has a phase advanced by an angle Δθ ₁ with respect to the lift characteristic a when the cam 4 is at the reference position, and the lift characteristic c has a phase delayed by an angle Δθ ₂ with respect to the lift characteristic a. ing.

Now, when the rotation angle range of the camshaft 3 from the start to the end of intake is called the valve working angle, it is compared with the valve working angle in FIG. 6 (a) under the same engine rotation speed. That in b) increases by the angle Δθ ₁ + Δθ ₂ , which means that the intake time becomes longer.

Since this embodiment operates as described above, by applying hydraulic pressure to the piston 10 in the high engine speed range where the intake time becomes short, the intake characteristic in this high engine speed range is improved. be able to.

Next, when the hydraulic pressure acting on the piston 10 is lowered, the repulsive force of the spring 13 causes the sliders 8 and 9 and the piston 10 to return to the positions shown in FIG. The size of the corner is suitable for the low engine speed range.

The hydraulic pressure applied to the piston 10 is controlled by the control system illustrated in FIG.

The engine rotation speed sensor 20 shown in the figure outputs a signal indicating the rotation speed of the engine, and this signal is a controller 21 including a microprocessor, a valve drive circuit, and the like.
Entered in.

Based on the output signal of the sensor 20, the controller 21 determines whether the engine is operating in the high rotation speed range or the low rotation speed range. When the controller 21 determines that the engine is operating in the high rotation speed range, the controller 21 outputs an electromagnetic valve drive signal, which causes the electromagnetic valve 22 to be switched.

With the operation of the electromagnetic valve 22, the sliding hole 3a located on the right side of the piston 10 shown in FIG. 1 and the hydraulic pump 23 are directly connected. As a result, the piston 10 is moved leftward, and the valve working angle shown in FIG. 6 (b), which is adapted to the high engine speed range, is set. The pump 23 is driven by the engine.

On the other hand, when the engine speed decreases to the low engine speed range, the controller 21
22 is deactivated. Therefore, the piston 10 is moved to the right,
The valve working angle shown in FIG. 6 (a) adapted to the low engine speed range is set.

Note that, instead of the speed sensor 20, it is also possible to use a sensor that detects the throttle opening, based on the actual engine speed when the former is used, and the target engine speed when the latter is used. Based on the above, the opening / closing control of the electromagnetic valve 22 is performed.

Further, although the electromagnetic valve 22 is on / off controlled in the above control system, the valve may be analog-controlled to continuously obtain a valve working angle according to a change in engine rotation speed. .

In the above embodiment, the guide hole formed on the camshaft 3 side
Although 3b and 3c are inclined and the concave grooves 4a and 5a provided in the cams 4 and 5 are along the axis of the camshaft 3, the same operation as above can be obtained even if the configuration is reversed. In this case, the sliders 8 and 9 may be integrally connected. Of course guide holes 3b, 3c
It is also possible to incline both the concave grooves 4a and 5a with respect to the axis of the camshaft 3.

Further, in the above embodiment, the pins 11 and 12 are attached to the sliders 8 and 9 and the concave grooves 4a and 5a are provided on the inner peripheral surfaces of the cams 4 and 5, but the configuration may be reversed. Good. However, in this case, it is necessary to provide means for restricting the rotation of the sliders 8, 9 with respect to the camshaft 3.

Furthermore, in the above embodiment, the sliders 8 and 9 are displaced by hydraulic pressure, but it is also possible to displace these sliders 8 and 9 using a power source such as an electromagnetic solenoid or an electric motor.

Further, although FIG. 1 shows the valve operating mechanism applied only to the intake valves 1 and 2, the valve operating mechanism of the present invention can be naturally applied to the valve operating mechanism of the exhaust valve. The valve operating mechanism of the present invention is not limited to a four-valve engine, but is applicable to any engine provided with a plurality of valves that perform the same action in one cylinder, regardless of the number of valves. be able to. Further, the present invention can be applied to an engine using a rocker arm.

[Effect of device]

According to the valve mechanism of the present invention, the angle range in which the valve is open (valve operating angle) can be changed, so that the valve operating angle adapted to the rotational speed of the engine can be obtained.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a valve mechanism according to the present invention, and FIGS. 2 and 3 show the positional relationship of pins at low engine speed and high engine speed, respectively. FIGS. 4 and 5 are cross-sectional views showing a mode of cam position change, FIG. 6 is a graph illustrating valve lift characteristics, and FIG. 7 is an example of a hydraulic control system. It is a block diagram. 1,2 ... Intake valve, 3 ... Cam shaft, 3a ... Sliding hole, 3b, 3c ... Guide hole, 4a, 5a ... Concave groove, 4,5 ... Cam, 8,9 ... Sliding Pendulum, 10 ... Piston, 11,12 ... Pin.

Claims (1)

[Scope of utility model registration request] 1. A valve mechanism, which is applied to a four-cycle engine having a plurality of valves that perform the same action in one cylinder, wherein the valve mechanism is rotatably fitted to a camshaft. And a second cam for activating at least one of the remaining valves and a remaining cam, respectively, and a cam rotation actuator, and the first and second cams are linked to the operation of the actuator. And a cam rotation means for rotating the reference position from the reference position in directions different from each other by a predetermined angle.