JPH0610633A - Valve system for engine - Google Patents

Abstract

PURPOSE:To control lift amount and phase continuously by forming the valve of a poppet valve type valve system in an engine installed on an automobile, a motorcycle or the like so as to achieve good durability and little friction loss. CONSTITUTION:This valve system is provided with a cam 2 and a rocker arm 3 disposed at the valve 4 of an engine to open and close the valve 4. A lengthwise sub rocker arm 11 is fitted between the cam 2 and the rocker arm 3, and the end of the sub rocker arm 11 is rotatingly-formed at the eccentric position of the surface of a displacement adjustment gear 6 which drives its rotation through a pin 10. Since the sub rocker arm 11 is used in a movable part, it is possible to achieve heavy load and high durability. Moreover, since a contact position of the sub rocker arm 11 with the cam 2 and the rocker arm 3 is moved continuously by rotating the displacement adjustment gear 6, it is possible to change valve operating phase and lift amount continuously and cope with low and high speed rotation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine mounted on an automobile, a motorcycle, etc.
The present invention relates to an engine valve operating device that controls a poppet valve type valve operating system in response to high speed rotation.

[0002]

2. Description of the Related Art Generally, an engine valve device is a DOH.
Taking a C-type engine as an example, as shown in FIG. 6, a cam 2 fixed to a pair of cam shafts 1 and a rocker arm 3 interlocking with the cams 2 are arranged, and are pressed by the rocker arm 3 to axially move. A sliding valve 4 is provided. An adjuster 5 is attached to the fulcrum of the rocker arm 3 to adjust the clearance. The rocker arm 3 is rotated by the cam 2 at a predetermined timing, and the lift amount of the valve 4 is set by the distance from the fulcrum of the rocker arm 3 to the contact point of the cam 2 and the pressing point of the valve 4.

When the valve (intake valve) 4 is driven from the low speed region to the high speed region with the same phase and the same lift amount, the intake air amount differs depending on each rotation speed, and accordingly, the air-fuel mixture inflow velocity into the combustion chamber also changes. . In the case where the high speed range is emphasized, the valve operating device is set so as to prevent the output from decreasing due to the inflow resistance when the amount of air-fuel mixture required to obtain the maximum output is inhaled. In the valve operating device, at a low speed, the air-fuel mixture inflow speed decreases, the turbulence of the air-fuel mixture in the combustion chamber decreases, and the combustion speed also decreases.

Therefore, a valve operating device which is efficient even at low speed has been proposed, and Japanese Utility Model Laid-Open No. 61-25514 discloses a structure for changing the fulcrum position of the rocker arm. It is designed to change the lift. That is, as shown in FIG. 7, the characteristic of the intake valve (In) can be controlled so as to change from a solid line curve to a dotted line curve. Further, in the valve operating device disclosed in Japanese Patent Laid-Open No. 62-121810, a plurality of rocker arms (three) are provided to change the timing stepwise so that the low speed region and the high speed region are exclusively operated. (See Figure 8).

[0005]

However, in the former valve operating system, the moving part and the sliding part are increased to change the fulcrum of the rocker arm, and the friction loss is increased. Further, since the gear is arranged at the fulcrum position, there is a problem that durability is deteriorated. Also, since the phases are the same, it is not possible to obtain optimum combustion conditions.

In the latter valve operating device, a sliding part for operating connection and disconnection of the three rocker arms is provided in order to obtain an operating state in a low speed region and a high speed region by combining a pair of intake valves and three rocker arms. Since the friction loss is increased, the weight is increased and the load applied to the camshaft and the like is increased, which makes high-speed operation difficult. Further, since the operating state is obtained only by the above combination, the valve characteristic becomes discontinuous even when the lift amount is changed, and the suitable combustion condition with respect to the engine rotation speed can only be obtained discontinuously.

According to the present invention, the valve lift of the engine is continuously adjusted and the phases thereof are continuously shifted so as to meet the operating conditions, and the durability is improved and the friction loss is small. The purpose is to provide a device.

[0008]

In order to achieve the above object, the present invention provides a valve operating system in which an engine valve is opened and closed via a cam and a rocker arm, and a long sub-rocker arm is provided with the cam and the rocker arm. The sub-rocker arm is mounted between the rocker arm and the end portion of the sub-rocker arm, and the end portion of the sub-rocker arm is rotatably provided via a pin at an eccentric position on the surface of a displacement adjusting gear that is rotationally driven.

[0009]

Since the present invention is configured as described above, when the displacement adjusting gear is rotated in one direction by a predetermined angle, the end portion of the sub-rocker arm, that is, the fulcrum moves. Further, the pressing point when the cam presses the rocker arm via the sub rocker arm moves. As a result, the phase pressed by the cam changes and the rocker arm ratio changes, so that the phase of valve operation and the lift change continuously.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, a displacement adjusting gear 6 is arranged between a pair of cam shafts 1 arranged in parallel on the cylinder upper part of the engine, and is connected to a driving device 8 such as a motor via a driving gear 7. ing. A pin pedestal 9 is fixed to the surface of the displacement adjusting gear 6, and a long sub-rocker arm 11 is rotatably attached via two pins 10 respectively.

The sub-rocker arm 11 is inserted between the cam 2 and the rocker arm 3, a buffer plate 12 is attached to the portion contacting the cam 2, and a spherical projection 11a is formed on the portion contacting the rocker arm 3. ing. A buffer plate 13 is attached to the rocker arm 3 at a position where the spherical projection 11a comes into contact with the rocker arm 3. The buffer plate 13 is rotatably provided with the adjuster 5 as a fulcrum to press the end of the valve 4. The valve 4 is opened and closed by being pressed by the rocker arm 3 and moving in the axial direction.

Next, the operation of the embodiment will be described. When the drive device 8 is actuated to rotate the displacement adjusting gear 6, the sub-rocker arm 11 moves the position (fulcrum) of the pin 10 to move the cam 2
The distance to the contact point of and the distance to the contact point of the protrusion 11a change. The driving device 8 is operated so that the positions of the two sub-rocker arms 11 are aligned, and the displacement adjusting gear 6 is moved.
Is rotated and stopped at a predetermined position. That is,
2 (a), the intake valve (In)
The characteristics of the exhaust valve (Ex) and the lift amount curve shown by the solid lines in FIGS. In this state, the maximum lift is set at the maximum engine torque.

When the lift amount and phase are changed depending on the engine speed, the drive device 8 is operated to change the posture of the sub-rocker arm 11, but at this time, the clearance at each connecting portion is changed. This change is absorbed by the adjuster 5, and the valve train is always in contact. When the posture of the sub rocker arm 11 changes from (b) to (e) shown in FIG.
It corresponds to the curves a, b, c, d and e showing the lift and phase of the valve 4 shown in FIGS. 3 and 4, respectively.

In FIG. 2A, the rocker arm ratio is maximized, and the phase change Δθ at this time is zero. In FIG. 2B, the rocker arm ratio becomes smaller,
Since the phase change Δθ goes to the plus side, the phase advances and the valve characteristic becomes the curve b shown in FIG. In FIG. 2C, the rocker arm ratio becomes the minimum. Further, the phase change Δθ becomes maximum and the valve characteristic becomes the curve c shown in FIG. In this way, the rocker arm ratio can be continuously reduced to reduce the wrist height and the phase can be continuously changed.

When the displacement adjusting gear 6 is rotated in the opposite direction, the posture of the sub-rocker arm 11 changes in the order of (d) and (e) of FIG. At this time, the valve characteristic is as shown in FIG.
The curves d and e shown in (1) change in this order, the phase lags behind the curve a, and the rocker arm ratio also changes at the same time, so the wrist height becomes low.

Further, as shown in FIG. 1, since the sub-rocker arm 11 can be extended to the intake valve (In) and the exhaust valve (Ex), the lift amount and phase of the intake valve and the exhaust valve are set to one in the DOHC engine. It can be changed by control. And
When the engine is operated at a low speed, the displacement adjusting gear 6 is rotated so as to lower the lift to adjust the posture of the sub-rocker arm 11 in order to reduce the friction of the valve train.

Further, by controlling the attitude of the sub-rocker arm 11, the following can be achieved. That is,
When the load is small, the lift can be delayed to reduce the compression pump loss, and when the load is low, the intake close can be accelerated to increase the torque. Further, when the intake close timing is considered to be more important than the lift amount at high rotation full load, the lift phase can be delayed a little at the output peak. Such a valve characteristic is as shown in the graph of FIG. 8, but can be changed according to the setting target. In addition, the slight adjustment of the characteristics is performed by the buffer plates 12, 13
It can also be done by changing the shape of.

[0018]

Since the present invention is configured as described above, since a long sub-rocker arm is used for the movable portion, it is strong against load and has high rigidity, and it is lightweight and follows high rotational motion. The durability can be improved. Also, since the contact point of the sub rocker arm with the cam and rocker arm can be moved continuously, the valve shaft height and phase can be continuously changed by the rotation of the cam shaft, and high torque and low torque can be maintained without impairing the maximum output. Fuel economy and low friction can be realized.

[Brief description of drawings]

FIG. 1 is a side view of a valve operating system for an engine according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing (a) to (e) the set positions of the sub-rocker arm of the valve operating system shown in FIG. 1 depending on the engine speed.

FIG. 3 is a graph illustrating an open / close state of intake / exhaust valves according to an embodiment.

FIG. 4 is a graph for explaining an open / close state of intake / exhaust valves according to an embodiment.

FIG. 5 is a graph showing the relationship between the rotation angle of the displacement adjustment gear and the engine speed of the embodiment.

FIG. 6 is a side view of a conventional engine intake / exhaust valve.

FIG. 7 is a graph showing the characteristics of a conventional variable intake valve lift for an engine.

FIG. 8 is a graph showing the characteristics of a device capable of varying the intake valve timing of a conventional engine.

[Explanation of symbols]

 2 Cam 3 Rocker arm 4 Valve 6 Displacement adjusting gear 10 Pin 11 Sub rocker arm

Claims (1)

[Claims] 1. A valve operating system in which a valve of an engine is opened and closed via a cam and a rocker arm, wherein a long sub-rocker arm is mounted between the cam and the rocker arm, and an end portion of the sub-rocker arm is attached. A valve operating device for an engine, which is rotatably provided via a pin at an eccentric position on a surface of a displacement adjusting gear that is rotationally driven.