JPH07116923B2 - 4-cycle engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-cycle engine in which three intake valves are provided on one side of a combustion chamber and a plurality of exhaust valves are provided on the other side, and these valves are driven by cam shafts. is there.

[0002]

2. Description of the Related Art Conventionally, in a four-cycle engine, in order to improve the output performance in a high-speed operation range, the number of intake valves and exhaust valves per cylinder has been increased. That is, by increasing the number of intake valves and exhaust valves, the total area occupied by the valves in the combustion chamber, that is, the valve area is increased and the intake and exhaust efficiency is improved. This is because the followability of the valve during high speed operation is improved. However, the area of the combustion chamber that each valve faces is limited, and there is a restriction that a plurality of valves must be provided within the area without interfering with each other.

Therefore, as shown in British Patent No. 687528, three intake valves are provided, and the intermediate valve is displaced to the outside of the cylinder from the valves on both sides in a side view so that the three intake valves are inside the combustion chamber. Some are provided without interfering with each other.

[0004]

By the way, in the case of the above-mentioned conventional example, since the distance between the upper end of each valve and the cam shaft is different, the valve having the intermediate rocker ratio of each rocker arm is used. And the valves on both sides are different. If the rocker ratio is to be made uniform among the valves to avoid this problem, the shape of the rocker arm must be changed for each valve, and the shape of the cam on the cam shaft must be largely different. However, there is a problem that the structure of the valve drive system becomes complicated.

The present invention has been made in view of the above problems, and an object thereof is to determine the rocker ratio of each valve when three intake valves are arranged so as to be offset from each other. , A rocker arm and a cam have substantially the same shape, and have a simple structure to provide a substantially identical four-cycle engine.

[0006]

In order to achieve the above object, a four-cycle engine according to the present invention has three intake valves on one side of a combustion chamber and a plurality of exhaust valves on the other side. Drive valves by camshafts 4
In a cycle engine, an intermediate valve among the intake valves is arranged to be offset to the outside of the cylinder from the others in a side view, and the upper ends of the offset valves are respectively inclined toward the outside of the cylinder. And make the upper ends of these intake valves close to each other in a side view,
One end of the rocker arm is brought into contact with the upper end of each intake valve, and the other end of the rocker arm extending toward the outside of the cylinder is coaxially supported, with a fixed distance from the supporting portion. The cam shaft is engaged with the rocker arm.

[0007]

According to the above construction, three intake valves are provided on one side of the combustion chamber and a plurality of exhaust valves are provided on the other side, and an intermediate valve among the intake valves is seen from the other side in a side view. Also, by arranging it so that it is offset to the outside of the cylinder,
Three intake valves are provided in the combustion chamber without interfering with each other to secure a large valve area in the combustion chamber.

Further, the upper ends of the above-mentioned mutually offset intake valves are inclined toward the outside of the cylinder,
The upper ends of these intake valves are brought close to each other in a side view, one end of each rocker arm is brought into contact with the upper end of each intake valve, and the other end of the rocker arm extending toward the outside of the cylinder is coaxial. Of the intake valves, the armor lengths of the rocker arms of the intake valves are substantially the same, and in addition to this, a certain distance from the support part is maintained with respect to the rocker arm. Since the camshafts are engaged with each other, even if a plurality of intake valves are arranged so as to be offset from each other in order to secure a large valve area, the cam engagement from the arm length of each valve and the support part By aligning the length to the joint, the rocker ratio of each valve is made almost the same,
Each valve can be synchronized and driven. When tuning each valve, it is possible to align the arm length of the rocker arm of each valve and the length from the support part to the cam engagement part, so the shape of the rocker arm and cam Does not have to be changed greatly for each valve.

Further, when the upper ends of the intake valves are brought closer to each other in a side view, the upper ends of the intake valves which are offset as described above are respectively inclined toward the outside of the cylinder, so that the umbrella portion of the intake valve facing the combustion chamber. The same direction, the surface area of the combustion chamber becomes smaller and the output of the engine can be increased, and the upper ends of the intake valves that are offset from each other are inclined toward the outside of the cylinder and the rocker arm Since the other end extending toward the outside of the cylinder is supported, the rocker arm support portion can be brought closer to the cylinder side.

[0010]

Embodiments of the present invention will be described with reference to the accompanying drawings. In the figure, a is a cylinder, b is a cylinder head, 1 is an intake passage, and 2 is an exhaust passage. Reference numeral 3 is a combustion chamber formed on the lower surface of the cylinder head b, and the intake passage 1 and the exhaust passage 2 are open. Reference numeral 4 denotes a screw hole for attaching a spark plug, which opens at the center of the upper surface of the combustion chamber 3. 5 is an intake valve for opening and closing the intake passage 1, 6
Is an exhaust valve that opens and closes the exhaust passage 2.

Lower ends of the intake valve 5 and the exhaust valve 6 respectively face the combustion chamber 3 and correspond to open ends of the intake passage 1 and the exhaust passage 2, and an intermediate portion of the cylinder head b through the guides 5a and 6a. It is slidably supported on the wall.

Reference numerals 7 and 8 are springs for urging the intake valve 5 and the exhaust valve 6 in the valve closing direction. Reference numerals 9 and 10 denote cam shafts that drive the intake valve 5 and the exhaust valve 6, and are rotatably held between the upper end of the cylinder head b and the cam caps 11 and 12, respectively. 13 is the cam shaft 9,
It is a cover that covers 10 and the cam caps 11 and 12,
It is connected to the upper end of the cylinder head b.

However, in order to improve the output performance of the four-cycle engine, the intake valve 5 per cylinder is
3 and two exhaust valves 6 are provided. And
Arrangement of the three intake valves 5 described above is provided with by offset in the cylinder outside in a side view than those of the intermediate of both sides, than the slope with respect to the axis 1 ₁ a cylinder a those center on both sides It faces the combustion chamber 3 so as to become smaller. That is, if the inclination angle of the intermediate intake valve 5 is α ₁ and the inclination angle of the intake valves 5 on both sides is α ₂ , then α ₁ <α ₂ .

[0014] Then, the three intake valves 5, as each upper end thereof close to each other in side view, and more particularly, substantially collinear parallel to the axis 1 ₂ camshaft 9
It is arranged so as to be located on the 1 _3. Therefore, the intake valve 5 is of a middle is displaced outward than both sides in the combustion chamber 3 in a plan view as shown in FIG. 2 with respect to the center line 1 ₄ to divide the its intake side and an exhaust side located Next to
The valves 5 do not interfere with each other.

Further, the intake valves 5 are respectively provided with the cam shaft 9
The rocker arm 14 is used as the connecting means. This rocker arm 14 is for each intake valve 5
Has three arms 14a which engages the upper end of each intake valve 5 the tip of its three arms 14a are located on the straight line 1 ₃
Of the cam 9a, which is in contact with the upper end of the cylinder head, is pivotally supported on the wall surface of the cylinder head b by a single support shaft 18 so as to be vertically swingable, and the upper surface of the intermediate portion is provided on the cam shaft 9. Is engaged with.

Therefore, the arm lengths of the rocker arms of each intake valve 5 are the same, that is, the length from the support shaft 18 to the upper end of each intake valve, and the length from the support shaft 18 to the engagement position of the cam 9a. , And the ratio of both (rocker ratio) is substantially the same in each intake valve 5. Thus, if the structure is such that the three intake valves 5 are driven by the rocker arm 14 that integrates the latter half of each arm 14a that abuts on the upper end of each intake valve 5 as described above, the camshaft 9 can be driven. Only one cam 9a needs to be provided, and moreover, the rocker ratios of the respective intake valves 5 can be made to coincide with each other to reliably synchronize the valve operation.

As a means for connecting the intake valve 5 to the cam shaft 9, an independent rocker arm 15 may be used for each valve 5 as shown in FIGS. 5 and 6. In this case, the rocker arm 15 is collinear 1 ₃ the tip
While abutting on the upper end of each intake valve 5 located above,
It is allowed supported by a bearing 18 'which extend the arms proximal generally axially 1 ₁ direction of the cylinder a. In this case, the rocker arms 15 can be of the same shape because the distance from the cam shaft 9 to the upper end of each intake valve 5 is substantially constant.
The cam 9a of the cam shaft 9 that engages with can also have the same shape.

Meanwhile, the intake valve 5 is due to that is the above such arrangement, the intake passage 1 is also the combustion chamber 3 and by reducing the inclination ones intermediate relative to the axis 1 ₁ of the cylinder a than that of both sides It faces the inside of the cylinder a. With such a structure, however, as in the conventional case where there are two intake passages and the inclinations of the cylinders with respect to the axis are the same, the intake airflows flowing in opposite directions from both intake passages on the way. It is possible to solve the problem of collision and stagnation, which makes it impossible to maintain a smooth intake flow.

That is, as shown in FIG. 7, in the cylinder a, the intake flow S ₃ from the intermediate intake passage 1 is aimed at the point where the intake flows S ₁ and S ₂ from the intake passages 1 on both sides collide.
Flows in, and the former intake air flows S ₁ and S ₂ are pushed down to collide with the piston c, and thereafter the cylinder a
Keep the flow within. As described above, the intake flow
S ₁ , S ₂ , S ₃ do not stagnant midway, and the intake flow S ₁ ,
The flow of S ₂ and S ₃ can be maintained smoothly.

Meanwhile, the exhaust valve 6 is provided two, it is disposed on the center line 1 ₄ parallel to the straight line 1 ₅ in the combustion chamber 3. Further, the exhaust valve 6 is set equal inclination angle alpha ₃ relative to the axis 1 ₁ of the cylinder a, are interlocking with the cam shaft 10 the upper end via a respective rocker arm 16. Since the exhaust valves 6 are two in number, they do not interfere even if they are arranged in series in the combustion chamber 3. However, according to the gist of the present invention, when viewed from the side, one of the two valves is outside the cylinder with respect to the other,
Alternatively, it may be arranged so as to be deviated to the cylinder center side.

[0021]

As described above, according to the present invention, it is possible to arrange the three parts on one side of the combustion chamber.
One intake valve, multiple exhaust valves on the other side,
Since the intermediate valve of the intake valves is arranged so as to be offset to the cylinder outer side than the others in a side view,
By providing the three intake valves in the combustion chamber without interfering with each other, it is possible to secure a large valve area in the combustion chamber.

Further, the upper ends of the above-mentioned offset valves are respectively inclined toward the outside of the cylinder, the upper ends of the intake valves are brought close to each other in a side view, and a rocker arm is attached to the upper ends of the intake valves. Since one end of each rocker arm is abutted and the other end of the rocker arm extending toward the outside of the cylinder is coaxially supported, the arm lengths of the rocker arms of each intake valve are substantially the same. Moreover, in addition to this, the camshaft is engaged with the rocker arm at a certain distance from the support portion, so that a plurality of intake valves are provided to secure a wide valve area. Even if they are arranged so that they are offset from each other,
The rocker ratio of each valve can be made substantially the same by arranging the frame length and the length from the supporting portion to the cam engaging portion, and the valves can be synchronized and driven. When tuning each valve, it is possible to align the arm length of the rocker arm of each valve and the length from the support part to the cam engagement part, so the shape of the rocker arm and cam Does not have to be changed largely for each valve, and its structure can be simplified.

Moreover, when the upper ends of the intake valves are brought closer to each other in a side view, the above-mentioned offset upper ends of the intake valves are respectively inclined toward the outside of the cylinder. The same direction, the surface area of the combustion chamber becomes smaller and the output of the engine can be increased, and the upper ends of the intake valves that are offset from each other are inclined toward the outside of the cylinder and the rocker arm Since the other end extending toward the outside of the cylinder is supported, the rocker arm support can be brought closer to the cylinder side, and the overall height of the engine can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a four-cycle engine according to the present invention.

FIG. 2 is a sectional view taken along the line EE of FIG.

FIG. 3 is a cross-sectional view taken along the line of FIG.

FIG. 4 is a sectional view taken along the line of FIG.

FIG. 5 is a vertical sectional view showing a modified example of the rocker arm according to the present invention.

FIG. 6 is a sectional view taken along the line Ni of FIG.

FIG. 7 is a schematic diagram showing a flow of an intake air flow in a cylinder according to the present invention.

[Explanation of symbols]

 a Cylinder 3 Combustion chamber 5 Intake valve 6 Exhaust valve 9,10 Cam shaft 9a, 10a Cam 14,15 Rocker arm 18 Spindle

Claims (1)

[Claims] 1. A four-cycle engine in which three intake valves are provided on one side of a combustion chamber and a plurality of exhaust valves are provided on the other side, and these valves are driven by cam shafts, respectively. Of the intake valves are arranged so as to be offset to the outside of the cylinder from the others in a side view, the upper ends of the mutually offset valves are inclined toward the outside of the cylinder, and the upper ends of the intake valves are viewed from the side. At the end of each intake valve, one end of the rocker arm is brought into contact with the upper end of each intake valve, and the rocker arm
The other end of the cam, which extends toward the outside of the cylinder, is coaxially supported, and the camshaft is engaged with the rocker arm at a certain distance from the supporting portion.