JPH065002B2 - Engine valve gear - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a valve operating system for an engine, and more specifically, a low speed cam and a high speed cam having different valve timings are provided in parallel, and the low speed cam is provided. The first to open and close by interlocking the valve to
The present invention relates to a valve operating device for an engine provided with a valve opening / closing mechanism capable of switching between a state and a second state in which a valve is interlocked with the high speed cam to open and close.

(Prior Art) In such a valve operating system of an engine, for example, when applied to an intake system, by opening and closing the intake valve with a low speed cam at low speed and opening and closing the intake valve with a high speed cam at high speed. At low speeds, the intake valve closing timing is accelerated to prevent the intake air from blowing back, and at high speeds, the intake valve closing timing is delayed to lengthen the intake time. Compared to the case where the intake valve is opened and closed at the same timing over the entire range, the intake charging efficiency can be increased and the output can be improved in both the low speed range and the high speed range. Moreover, since the valve timing is not continuous but is changed stepwise by switching the cam to be used, for example, the configuration for changing the valve timing is simplified compared to the case where the valve timing is continuously changed. Therefore, it is easy to improve the reliability and reduce the cost.

And in the conventional valve operating system for such an engine,
The high speed cam and the low speed cam are configured such that the profile of the high speed cam includes the profile of the low speed cam, and a rocker arm that is driven by the low speed cam to open and close the valve is provided. , An interlocking device that is fixed in a state of sliding contact with a high-speed cam and can switch between a state in which the rocker arm is interlocked with the high-speed cam so that the rocker arm is driven by the high-speed cam, and a state in which the interlocking is released, and The valve opening / closing mechanism was configured by attaching a fixing mechanism for fixing and releasing the interlocking device (for example, Japanese Utility Model Laid-Open No. 57-182205).

However, when the conventional valve operating device is used, since the coupler and the fixing mechanism are attached to the rocker arm, the rocker arm becomes heavy, and the followability of the rocker arm to the cam at high speed is poor, and the rotation limit is limited. It was low.

(Problems to be Solved by the Invention) The present invention has been conceived in consideration of such a point, and an object thereof is to improve a rotation limit.

(Means for Solving the Problems) The characteristic structure of the valve operating system for an engine according to the present invention, which has been devised to achieve the above object, is characterized in that the low speed cam profile includes the high speed cam profile. On the other hand, a high-speed rocker arm that is driven by the high-speed cam to open and close the valve and a low-speed rocker arm that is driven by the low-speed cam are provided, and the high-speed rocker arm follows the low-speed rocker arm. Can be switched between an interlocking state in which the high-speed rocker arm is interlocked with the low-speed rocker arm so that it rocks, and an interlocking release state in which the interlocking is released so that the high-speed rocker arm swings in response to the high-speed cam. It is the point that the valve opening / closing mechanism is configured by providing various interlocking devices.
The effects are as follows.

(Operation) Basically, the high-speed rocker arm is used to open and close the valve, and at low speed, the low-speed rocker arm driven by the low-speed cam is connected to the high-speed rocker arm so that the high-speed rocker arm is operated for low speed. Since it is driven by a cam and the valve is opened and closed by a low speed cam, the movable member for opening and closing by interlocking the valve with the high speed cam at high speed is one of the high speed rocker arms and has a small inertial mass. It is possible to improve the followability of the valve to the high speed cam.

(Effect of the Invention) Therefore, according to the present invention, there is provided an engine valve operating device capable of improving the output by switching the valve timing by selecting the use of the low speed cam and the high speed cam and improving the rotation limit. I was able to do it.

(Example) Hereinafter, the Example of this invention is described based on drawing.

As shown in FIGS. 1 and 2, the engine has two intake ports (1) and one exhaust port (2) per cylinder, that is, two intake valves (3) and one exhaust valve ( 4) is equipped.

As shown in FIGS. 3 to 5, the valve operating device for opening and closing the valves (3) and (4) for both kinds is a spring for moving and urging the valves (3) and (4) in the closing direction. In addition to providing (7) and (8), one camshaft (10) driven synchronously by a crankshaft (not shown) is provided at the center of the cylinder head (9) in the width direction. A valve opening / closing mechanism (11) that opens and closes each valve (3), (4) with the rotation of (10),
(12) is provided and configured.

The camshaft (10) has a low speed cam (13A) and a high speed cam (13A) at different timings for closing the intake valve (3).
B) and exhaust cam for opening and closing the exhaust valve (4)
(14) and are installed side by side. The low speed cam (13A) is formed on both sides of the high speed cam (13B), and both cams (13A) and (13B) have the base circle diameter of the low speed cam (13A) equal to the high speed cam. The profile of the low speed cam (13A) is made larger than the base circle diameter of (13B) so as to include the profile of the high speed cam (13B).

The valve opening / closing mechanism (11) for the intake valve (3) has a first state in which the intake valve (3) is opened / closed by interlocking the low speed cam (13A) and the intake valve (3) for the high speed cam (13B). It can be switched to a second state of opening and closing in conjunction with each other, and is specifically configured as follows.

In other words, the high speed cam (13B) swings with the rotation of the high speed cam (13B) to open and close the intake valve (3) at one end.
(B) and a high speed rocker arm (15B) that is in sliding contact with the intake valve (3) at the other end and a low speed cam (15B) at one end so as to swing with the rotation of the low speed cam (13A). 1
3A) and a low-speed rocker arm (15A) slidably supported on rocker shafts (16) respectively, and the high-speed rocker arm (15B) follows the low-speed rocker arm (15A). The rocker arm for high speed (15B) interlocks with the rocker arm for low speed (15A) so that the rocker arm (15B) for high speed rocks in response to the cam (13B) for high speed. By providing a selector mechanism that can be switched to the interlock release state that releases the interlock,
It is configured. In summary, by switching the selector mechanism to the interlock release state, high-speed rocker arm (15
B) High speed cam independent of low speed rocker arm (15A)
(13B) swings to open and close the intake valve (3) at the high speed valve timing, and by switching the selector mechanism to the interlocking state, the high speed rocker arm (15B) is connected via the low speed rocker arm (15A). ) Is swung by the low speed cam (13A) to open and close the intake valve (3) at the low speed valve timing.

The selector mechanism is slidable in the swinging direction with respect to the low speed rocker arm (15A) and
By being fixed to an operating position where it projects toward the (15B) side and abuts against the high-speed rocker arm (15B), the high-speed rocker arm (15A) swings in the valve opening direction along with the high-speed rocker arm (15A). 15B) to push the high-speed rocker arm (15B) into the low-speed rocker arm (15B).
Interlocking pin (17) that follows and oscillates, and this interlocking pin (17)
The spring (18) for urging the lever to move toward the protruding side and the interlocking pin (17) are slidable along the axis of the rocker shaft (16) only when the interlocking pin (17) is in the sliding position. Due to, the peripheral groove (17a) formed on the interlocking pin (17)
To the lock position to lock the interlocking pin (17) to the working position by engaging with the interlocking pin (17) by releasing the engagement with the circumferential groove (17a).
A lock plate (19) for changing the position to a release position that allows the slide of is attached to the low speed rocker arm (15A), and a spring (20) for urging the lock plate (19) to the release position, A hydraulic cylinder (2) that slides the lock repute (19) to the locked position against the biasing force.
1) and are provided and configured. The hydraulic cylinder (21)
Is an annular one that is fitted onto the rocker shaft (16) and is controlled by a microcomputer based on the engine speed. (25) is an adjusting screw for valve clearance adjustment, (26)
Forms a pin contact surface on the high-speed rocker arm (15B) side, and both rocker arms (15A) and (15B) are connected to the cam (13A),
(13B) is an adjusting screw that adjusts the pin contact surface so that the interlocking pin (17) that slides to the operating position in the state of sliding contact with the base circle surface of (13B) accurately contacts, and (27) is the hydraulic cylinder Is the oilway to (21),
(28) is a spring for urging the high speed rocker arm (15B) in the valve closing direction.

A valve opening / closing mechanism (12) for the exhaust valve (4) slides on the exhaust cam (14) at one end so as to swing with the rotation of the exhaust cam (14) to open and close the exhaust valve (4). contact,
Further, a rocker arm (30), which is in contact with the exhaust valve (4) at the other end via a valve clearance adjusting screw (29), is supported by a rocker shaft (31).

(32) is a fuel injection valve, and (33) is a head cover.

According to the above configuration, at the time of high speed, the intake valve is attached to the high speed cam.
The movable member for interlocking and opening (3) is one of the high-speed rocker arms (15B), which has a small inertial mass and excels in the followability of the intake valve (3) to the high-speed cam at high speed.

It should be noted that the present invention is the high-speed cam (13B) as in the above embodiment.
Rather than forming the low speed cams (13A) on both sides of each, the high speed cams (13B) are formed on both sides of the low speed cam (13A) as shown in FIG. Is also good. In this case, the sliding contact portion of the high speed rocker arm (15B) with the high speed cam (13B) naturally has a bifurcated shape.

Further, although the above embodiment is applied to the intake system, it is needless to say that the present invention can be applied to the exhaust system.

[Brief description of drawings]

1 to 5 show an embodiment of the present invention, FIG. 1 is a vertical sectional front view of an essential portion, FIG. 2 is a cross-sectional plan view of the essential portion, FIG. 3 is a vertical sectional side view of the essential portion, FIG. 4 is a vertical sectional front view of a main portion showing an intake valve open state at a low speed valve timing, and FIG. 5 is a vertical sectional front view of a main portion showing an intake valve open state at a high speed valve timing. FIG. 6 is a schematic plan view of a main part showing another embodiment. (3) …… Valve, (13A) …… Low speed cam, (13B) …… High speed cam, (11) …… Valve opening / closing mechanism, (15B)
...... High-speed rocker arm, (15A) …… Low-speed rocker arm, (17) …… Interlocking tool.

Claims (1)

[Claims] 1. A first state in which a low-speed cam and a high-speed cam having different valve timings are arranged in parallel, and the valve is linked to the low-speed cam to open and close, and the valve is linked to the high-speed cam to open and close. In a valve operating system of an engine provided with a valve opening / closing mechanism that can be switched to a second state, the cams for low speed include both cams so that the profile of the cam for high speed includes the profile of the cam for high speed. A high-speed rocker arm that is driven by a cam to open and close the valve, and a low-speed rocker arm that is driven by a low-speed cam are provided, and the high-speed rocker arm follows the low-speed rocker arm and swings at a high speed. The rocker arm for high speed is interlocked with the rocker arm for low speed and the high speed rocker arm is interlocked so that it rocks in response to the high speed cam. Valve operating device provided with a disengagement state and the switchable interlocking device engine have configured the valve opening and closing mechanism.