WO1996011325A1

WO1996011325A1 - Suction-exhaust valve control device for a four cycle engine

Info

Publication number: WO1996011325A1
Application number: PCT/JP1995/002063
Authority: WO
Inventors: Hiroomi Ogasawara
Original assignee: Ogasawara Precision Engineering Ltd.
Priority date: 1994-10-11
Filing date: 1995-10-09
Publication date: 1996-04-18
Also published as: JPH08109812A; DE19581378T1

Abstract

Industrial field of utilization: the present invention relates to a device for changing the operation timing of suction and exhaust valves of a four cycle engine, and more particularly to a device for changing a timing at which the operation of a cam is transmitted to a valve and a valve lift. Problem: an object of the present invention is to provide a variable suction-exhaust device simple in construction and capable of effecting suction and exhaust in accordance with an engine speed. Means for solving the problem: a suction and exhaust valve control device for a four cycle engine comprising a cam (1) for determining the operation timing of at least one of suction and exhaust valves and a valve disc (8, 14) adapted to be operated by being pressed down in accordance with the rotation of the cam to thereby press down at least one of the valve discs of the suction and exhaust valves, wherein a cam follower (2) or the cam follower and a rocker arm (5, 15) are inserted between the cam and the valve disc, the cam follower being adapted not only to transmit the cam operation of the cam to the valve disc but also to be able to change its attitude in accordance with an external force so as to change the contact position relative to the cam to thereby change a timing at which the cam operation of the cam is transmitted to the valve disc and a valve lift.

Description

Harm

Supply / exhaust valve control system for 4-cycle engine

The present invention relates to a device for changing the operation timing of a supply / exhaust valve of a four-cycle engine, and more particularly to a device for changing the timing of transmitting the operation of a cam to a valve and the valve lift.

Background art

The supply and exhaust of the engine is performed by operating at least one of the intake and exhaust valves according to the rotation of the cam. In addition, the charging efficiency and the combustion efficiency are not the best if the timing of the supply and exhaust of the engine is not changed between the low and high engine speeds. In other words, the higher the engine speed, the faster the supply and exhaust timing needs to be. For this reason, conventionally, there has been provided a technology that uses two types of cams, such as VTEC and MIVEC, to adjust the timing of air supply to the engine combustion chamber and further the timing of exhaust air according to the engine speed.

A helical gear called VANOS is used to change the force acting on at least one of the cam-operated intake and exhaust valves, and the helicopter gear rotates according to the separately detected engine speed. In some cases, the degree of action fe¾ is changed.

Since these devices use two types of cams or helical gears, the cam advance and the valve lift cannot be controlled simultaneously and continuously, and the charging efficiency and combustion efficiency are always optimized. Not only cannot it be maintained, but the overall mechanism has a complicated configuration. The present invention has been made in consideration of the above points, and has as its object to provide a four-stroke engine integrated exhaust valve control device that can perform variable supply and exhaust according to the engine speed in a simple manner.

Disclosure of the invention

In order to achieve the above object, in the present invention,

A cam that determines the timing of at least one of an air supply valve and an exhaust valve of the engine, and a valve body that is pressed in accordance with the rotation of the cam and pushes down at least one of the air supply valve and the exhaust valve. In the lined exhaust valve control device of a 4-cycle engine, the cam operation of the cam is applied to the valve body between the cam and the valve body, and ^ is changed according to an external force. A four-cycle engine, wherein a cam follower that changes the timing and the valve lift amount of the cam that moves the cam to the valve body by changing the contact position with respect to the cam, or a rocker arm is further inserted. Lined exhaust valve control device,

Is provided.

The following effects can be obtained by the above steps.

The operating timing of at least one of the exhaust and exhaust valves of the engine determined by the cam is transmitted to the valve via the cam follower. The cam follower can change its length when an external force is applied, and by changing the posture, the phase angle position that contacts the cam changes, so the timing of receiving the operation from the cam changes. As a result, the timing of the valve element changes to change the timing relationship between the cam operation and the operation of the valve element, so that the engine charging efficiency and combustion efficiency corresponding to the engine speed can be optimized. In addition, changing the posture of the cam follower changes the contact position force with the valve body, so the valve lift also changes. The movement of the cam follower may be further transmitted to the valve via a rocker arm. Brief description of EI®

FIG. 1 (a) is a vertical cross-sectional view of the supply and discharge periphery of a four-stroke engine to which the present invention is applied, and FIG. 1 (b) is a partial detailed view of FIG. 1 (a).

FIG. 2 is a diagram for explaining the operation of the supply / exhaust timing according to the present invention. FIG. 2 (a) shows the case of normal timing, and FIG. 2 (b) shows the case of early timing. FIG.

FIG. 3 is a view showing a rotary member 3 in the example of FIG.

FIG. 4 is a schematic diagram illustrating the operation of the cam follower in the example of FIG. 1.

FIG. 5 is a simplified diagram of FIG. 4 illustrating the operation of the cam follower in the example of FIG. 1; FIG.

FIG. 6 is a characteristic diagram showing the relationship between the inclination angle of the cam follower and the rate of change of the valve lift in the example of FIG.

FIG. 7 is a diagram showing the relationship between the inclination angle of the cam follower and the change Ut in the clearance of ^ which comes into contact with the cam follower in the example of FIG.

FIG. 8 is a view showing another example of the angle H of the present invention. FIG. 8 (a) shows a state viewed from the same angle as FIG. 1, and FIG. 8 (b) shows an X-X of FIG. It shows the condition viewed along the direction.

FIG. 9 is a longitudinal sectional view showing the supply and discharge of another HJI example of the present invention, and FIG.

9 (a) is a partial detailed view.

FIG. 10 is a diagram for explaining the change <b operation of the supply / exhaust timing according to the present invention.

10 (a) shows the case of normal timing, and FIG. 10 (b) shows the case of early timing.

FIG. 11 is a view showing another embodiment of the present invention. FIG. 11 (a) shows a state viewed from the same angle as FIG. 9, and FIG. 11 (b) shows a state of FIG. 11 (a). X—shows the state viewed along the X direction. DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIGS. 1 (a) and 1 (b) show, as an Hlfe form of the present invention, a vertical cross section around a supply / exhaust valve of a four-stroke engine. As shown, the engine or air-fuel mixture is introduced into the cylinder through an air supply port 10 and is discharged from an exhaust port 20 after compression and combustion.

FIG. 1 shows only the details of pfling the air supply valve provided in the air supply hole 10 and omits the other components.The same configuration is applied to the exhaust valve provided in the exhaust hole 20. Or ^!

The fl of the air supply valve is controlled by the operation of the cam 1. The cam 1 rotates clockwise in the figure synchronously with the rotation of the engine, pushes down the valve body via another member at a predetermined rotation position against the extension of the spring incorporated in the air supply valve, and forms a line. Air is supplied to the cylinder from the pore 10.

There is a cam follower 2 as a main element for transmitting the cam operation of the cam 1 to the air valve at this time. The cam follower 2 is formed in a columnar shape as shown in FIG. 1 (a), and is accommodated in a through-hole provided in a cylindrical rotating body 3 so as to be movable in the axial direction or "5J-capable." As shown in Fig. 1 (b), the cam follower 2 may have a large diameter at the contact portion with the cam and a thinner guide portion, that is, may have a so-called mushroom-like shape. The pressing force of the body is fitted to the valve body 8 via the hemispherical body 4. The hemispherical body 4 is in sliding contact with the upper surface of the valve body 8 in the figure, and the pressing force from the cam follower 2 is applied to the valve. A downward force in the figure is given to the body 8. Therefore, a force for pushing down the valve body 8 against the extension force of the spring 7 is given to the upper end face in the drawing of # ί * 8.

When the valve element 8 is pushed down, the end of the air supply hole closed by the valve element 8 is opened, and the air is communicated with the air supply hole 10 and the cylinder, and a solid air is performed.

Although not shown or described in detail, a similar valve is provided between the exhaust port 20 and the cylinder. An operation for exhausting by the operation is performed.

2A and 2B are diagrams for explaining the operation of changing the supply / exhaust timing according to the present invention. FIG. 2A shows the case of normal timing, and FIG. 2B shows the case of early timing.

First, in FIG. 2A, the cam 1 rotates clockwise in the figure and comes into contact with the upper surface of the cam follower 2 in the figure. As a result, the cam follower 2 is pushed down in the axial direction along the through hole of the rotating body 3 and pushes down the hemispherical body 4.

Next, in the same figure (b), the rotating body 3 is rotated counterclockwise by an angle 0 as compared with the state of the same figure (a), and the cam follower 2 is in an inclined state with respect to the cam 1. . For this reason, the cam follower 2 first comes into contact with the cam 1 at the right end of the upper surface in the figure. The upper surface of the cam follower 2 is shifted rightward in the drawing when viewed from the center axis of the cam follower 2, and thus is the portion of the upper surface of the cam follower 2 that comes into contact with the cam 1 first. Therefore, in the case of FIG. 7 (a), the cam follower 2 responds to 3 カム of the cam 1 earlier than in FIG. 7 (a). If the inclination angle of the cam follower 2 is reversed in the clockwise direction, the cam follower 2 responds to the movement of the cam 1 with a delay.

Therefore, if the rotation angle of the rotating body 3 is changed in accordance with the engine ¾g, the cam follower 2 changes the force with respect to the cam 1 in accordance with the engine speed. If the cam follower 2 contacts the cam 1 at ^ shown in the same figure (a) when the engine speed is high, the cam follower 2 contacts the cam 1 at ^ shown in the same figure (b) at high speed. For example, by rotating the rotating body 3 through a control mechanism (not shown) or a link mechanism operated by an actuator such as a hydraulic pressure, supply and exhaust at high speed is performed earlier than engine rotation. .

Therefore, air supply and exhaust are performed according to the engine speed.

FIG. 3 shows the shape of the rotating body 3. The rotating body 3 is The rotating body 3 has two through holes 3 a, 3 a which are substantially cylindrical in shape, are arranged side by side along the longitudinal direction thereof, and extend from one of the peripheral surfaces of the rotating body 3 to the other. The cam follower 2 is accommodated in the through hole 3a so as to be movable in the axial direction in the through holes 3a and 3b. In this case, a longer rotating body 3 common to a plurality of cylinders and having only two valves in the DOHC engine may be formed. As a result, it is possible to change the value of the force follower 2 of a plurality of cylinders in a single control mode or in a hydraulic operation.

At least one end surface of the rotating body 3 is provided with a connecting portion 3b, and the connecting portion 3b is subjected to IE® connection with a control mechanism or a hydraulic device provided by a link mechanism (not shown). By changing the rotation angle of the rotating body 3, the posture of the cam follower 2 is changed.

4 and 5 show how the rate of change of the valve lift changes due to the rotation of the cam follower 2 in the example H of FIG. 1 due to the rotation of the rotating body 3, and the upper limit position of the cam follower 2. That is, FIGS. 6 and 7 are schematic diagrams for explaining how the clearance between the cam follower pushed up by the valve spring and the rotation limit position for taking two forces changes. The cam follower 2 has a total length St of 5 O mm, and pivots to a position at an angle 0 with a point at a distance S from the contact surface with the cam 1 as a fulcrum. The lower end of the cam follower 2 is in contact with the valve body 8 via the hemispherical body 4.

This schematic diagram shows a state in which the cam follower 2 abutting on the cam 1 is in an upright state, which is a reference state, and a state in which the cam follower 2 rotates about the rotation center C f and rotates to a position of an angle 0 indicated by the idea. .

In particular, in Figure 5, the function of the cam follower drawn in rectangle in Figure 4 is shown in a T-shape for easy understanding.

FIG. 6 is a characteristic diagram obtained by performing a simulation under the conditions of FIG. The horizontal axis indicates the tilt angle 0 of the cam follower 2, and the vertical axis indicates the lift of a valve (not shown). In this case, the fulcrum position of the cam follower 2 is seven steps in increments of 5 mm, with the distance S from the upper end of the cam follower 2 in the range of S = 10 mm to 4 Omm. As a result, the valve lift is +8 when the tilt angle is 0. At 130 to 148% at 80 ° to 80% to 75% at 18 °, and by changing the tilt angle from + 8 ° to 18 ° arbitrarily, the valve lift within the above range Rate is obtained. The change of the valve lift can be estimated by the following formula (1).

L '= {A / (A-X)} XL> L (1) Thus, it can be seen that the valve lift can be significantly changed by selecting the 2 position of the cam follower 2.

FIG. 7 is a characteristic diagram obtained by performing a simulation under the conditions of FIG. 4 in the same manner as in FIG. 6, in which the inclination angle 0 of the cam follower 2 is plotted on the horizontal axis, and the change in the clearance of the cam follower 2 (ΛΔ1 is plotted on the vertical axis). The clearance between the cam and the cam follower must be within a range that can absorb this change, and the clearance change amount 1 can be obtained by the following equation (2).

1 = (Γ + l) — {(r + 1) cos 0 + (r + S) s i n2 Θ)

(2)

When the position of S is the distance S from the upper end of the cam follower 2, the clearance change ίί ^ Δ1 when the inclination angle 0 is 8 ° in the range of S = l 8.7mm to 19.1mm is less than 4 m It varies in the range of +3 m. If the clearance changes in such a range, there is no practical problem. Since the clearance change 1 requires the precision of the valve lift explained in Fig. 6, it is necessary to consider the clearance change bfi when selecting the fulcrum position of the cam follower 2. If the fulcrum position is selected as S = l 8.8 mm, the change in clearance b * can be reduced to almost zero until the inclination angle S is 5 °, and if the ^ position is selected as S = 18.9 mm, Tilt angle The change in clearance bS can be kept within 1 to around 8 °. Also, the valve opening angle can be reduced by arranging the clearance in a direction to increase the clearance.

FIGS. 8A and 8B show another example of the present invention, in which the cam follower 12 is formed in an umbrella shape and supported by a ring 13. The ring 13 is supported by the cylinder head by a force (not shown) << a well-known structure. The ring 13 may be not cylindrical but notched as long as it can support the cam follower 12. In this case, the upper surface in the figure of ##: 14 is an arc surface with a radius R centered on the cam shaft.

FIG. 9 shows a state similar to that of FIG. 1 according to still another embodiment of the present invention. C FIG. 9 also shows only the opening of the air valve provided in the air supply hole 10 in detail. The other components are omitted. The same configuration can be applied to the exhaust provided in the exhaust hole 20.

The p¾l of the air supply valve is controlled by the operation of the cam 1. The cam 1 rotates clockwise in the figure synchronously with the rotation of the engine, stakes at a predetermined rotation position under the tension of the spring incorporated in the lined air valve, pushes down the valve body via another member, and supplies the power. Vent from cylinder 10 to cylinder.

The main elements for transmitting the cam operation of the cam 1 to the air valve at this time are the cam follower 2 and the rocker arm 5 as a valve F 弁 member. The cam follower 2 is formed in a columnar shape, and is accommodated in a through hole provided in the cylindrical rotating body 3 so as to have an axial moving force. Further, as shown in FIG. 9 (b), the cam follower 2 may have a so-called mushroom-like shape in which the diameter of the contact portion with the force is large and the guide portion is thinner than that.

The pushing force of the valve body by the cam follower 2 is transmitted to the rocker arm 5 through the hemispherical body 4. The hemisphere 4 slides on the upper surface of the rocker arm 5 in the figure. The cam follower 2 is being touched, and the pressing force from the cam follower 2 is applied to the mouth kicker arm 5 downward in the figure. For this reason, the rocker arm 5 rotates counterclockwise in the figure, and applies a force to push down the valve body 8 against the extension force of the spring 7 to the illustrated upper end of the valve body 8 via the spherical body 6.

The rocker arm 5 receives a clockwise acting force due to the extension force of the spring 7, and rotates to a preset operation position around a rotation center near the right end in the figure. Then, it receives an acting force from the cam follower 2 and gives an acting force to # <* 8.

Among the elements provided on the path of this acting force, the rocker arm 5 is a member for applying the acting force received from the force follower 2 to the valve element 8. If the point where the acting force is received from the force follower 2 and the point applied to the valve element 8 are only slightly small in position and are not separated from each other, the strength of the rocker arm 5 does not need to be increased so much.

When the valve element 8 is pushed down, the end of the air supply hole closed by the valve element 8 opens, and the air hole 10 and the cylinder are connected to supply air.

Although not shown or described in detail, the same operation for exhaust is performed between the exhaust hole 20 and the cylinder by the same valve operation.

FIG. 10 is a diagram for explaining the operation of changing the supply / exhaust timing in the embodiment of FIG. 9. FIG. 10 (a) shows the case of normal timing, and FIG. 10 (b) shows the case of early timing. Each is shown.

First, in FIG. 2A, the cam 1 rotates clockwise in the figure and comes into contact with the upper surface of the cam follower 2 in the figure. As a result, the cam follower 2 is pushed down in the axial direction along the through hole of the rotating body 3, and pushes down the hemispherical body 4 to apply a force to the cam follower 5.

Next, in the same figure (b), the rotating body 3 is turned counterclockwise by an angle 0 compared to the state of the same figure (a). The cam follower 2 is rotating with respect to the cam 1. For this reason, the right end of the upper surface of the cam follower 2 in the figure comes into contact with the cam 1 first.c And the right end of the upper surface of the cam follower 2 is shifted to the right side of the drawing when viewed from the center axis of the cam follower 2. This is the portion of the upper surface of the cam follower 2 that comes into contact with the cam 1 first. In the case of FIG. 7 (a), the force of the cam 1 responds to the movement of the cam 1 two times earlier than the force of FIG. 7 (a). If the inclination angle of the cam follower 2 is reversed in the clockwise direction, the cam follower 2 responds to the movement of the cam 1 with a delay.

Therefore, if the rotation angle of the rotating body 3 is changed in accordance with the engine speed, the cam follower 2 changes ^ with respect to the cam 1 in accordance with the engine speed. If the cam follower 2 contacts the cam 1 at ^ shown in the same figure (a) when the engine speed is low, the cam follower 2 contacts the cam 1 at ^ shown in the same figure (b) at high speed. For example, by rotating the rotating body 3 through a link (not shown) that is controlled by a control motor or an actuator such as a hydraulic pressure, air supply and exhaust at a high speed are performed earlier than the engine rotation. .

Therefore, air supply and exhaust are performed according to the engine speed.

FIGS. 11A and 11B show another example of the present invention, in which a cam follower 12 is formed in an umbrella shape and supported by a ring 13. The ring 13 is supported by a cylinder head by a well-known configuration (not shown). The ring 13 may be not cylindrical but notched as long as it can support the cam follower 12.

Then, the stroke motion of the cam follower 12 reaches the valve body via the rocker arm 15.

As a modification to the above example, the position of the cam follower 2 may be offset in the advance direction, that is, in the direction shown in the figure with respect to the center position of the cam 1. O

By adding such ^, it is possible to select various timings at which the operation of the cam 1 is fed to the cam follower. In addition, EJt can be determined for the cam follower 2 to determine.

Available for H ±

According to the present invention, since the operation of the cam is transmitted to the valve body via a force follower that changes the contact position with respect to the cam when the external force is applied and the force changes, the cam follower can be changed according to the engine speed. The operation to the valve body can be performed at timing that changes according to the speed. As a result, the operation of at least one of the supply valve and the exhaust valve can be changed according to the engine ¾S. Also, by changing the contact position between the cam follower and the valve body, the force to change the valve lift can be achieved. In addition, since the present invention has the structure of the upper part of the cylinder head of the engine, the present invention can be similarly applied to a case where the present invention is applied to an existing engine.

Claims

The scope of the claims

1. At least one of the engine's air supply valve and exhaust valve is determined by the cam and the cam is pressed in accordance with the rotation of the cam, and at least one of the exhaust valve and the exhaust valve is turned off. In a 4-cycle engine supply / exhaust valve control device with a valve body to push down,

Between the cam and the valve element, the cam operation of the cam is applied to the valve element, and the attitude of the cam is changed according to an external force to change the contact phase angle with respect to the cam. A feed / discharge control device for a four-stroke engine, wherein a cam follower for changing the timing of the operation of the valve body and the valve lift is inserted.

2. Claim 1 § In the device on my own,

Between the force and the valve operating member, the force operation of the cam is controlled by the valve F¾ member, and the contact phase angle with respect to the cam is changed by changing the force according to an external force. A supply / exhaust valve control device for a four-cycle engine, wherein a cam follower and a rocker arm for changing a timing for transmitting an operation to the valve member and a valve lift amount are inserted.

3. The apparatus according to claim 1,

A rotating body having a cylindrical hole connecting the cam and the valve body and rotating about a rotation center line parallel to a rotation axis of the cam;

A supply / exhaust valve control device for a four-cycle engine, which is supported in the hole of the rotating body so as to be movable in the axial direction of the cam faw port.

4. The apparatus according to claim 1,

Said engine has one or more cylinders,

The rotating body is provided in common for each cylinder. Control device.

5. The apparatus according to claim 1,

The cam follower is a four-cycle engine supply / exhaust valve control device which is offset from the rotation center of the cam in the advance direction.