JPH01253508A - Four-cycle engine - Google Patents

Abstract

PURPOSE:To improve compression ratio and heat efficiency by arranging the vertical line of shaft center of an intake camshaft on a plane which passes an axis of an intermediate intake valve of the three and crossing perpendicularly the intake camshaft and thereby reducing volume and area of a combustion chamber. CONSTITUTION:A four-cycle engine has, per cylinder, three intake valves 5 and a plurality of discharge valves 6 which are driven by a camshaft 9. The intermediate intake valve 5 faces a combustion chamber 3 with its inclination to an axis l1 of a cylinder (a) being smaller than those of both side intake valves 5. A vertical line l6 of a shaft center O1 of the intake camshaft 9 on a surface perpendicularly crossing the intake camshaft 9 passing an axis l2 of the intermediate intake valve 5 is arranged on a space A between an intersection 5b of the axis l2 of the intermediate intake valve 5 and the valve lower end face, and an intake side wall of the cylinder (a).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a four-stroke engine having three intake valves and a plurality of exhaust valves per cylinder.

[Prior Art] Each cylinder has three intake valves and three exhaust valves, each of which is driven by a camshaft above the intake valve, and the middle intake valve among the intake valves is driven by the intake valves on both sides. For example, British Patent No. 296125 describes an engine in which the inclination of the cylinder with respect to the axis is reduced so that it faces the combustion chamber. It is known as shown in I@.

Further, each cylinder has two intake valves and one exhaust valve, each of which is driven by a camshaft above the two, and the two intake valves face the combustion chamber with opposite inclinations. Such engines are also known, for example as shown in US Pat. No. 3,211,137.

[Problem to be Solved by the Invention] Incidentally, in the above-mentioned known engine, three intake valves per cylinder are arranged using approximately 1/2 of the cylinder. The vertical line of the axis of the intake camshaft in a plane that passes through the axis of The problem is that the angle between the cylinder axis and the axis of the intake valves on both sides of the valve becomes large, and as a result, the volume of the combustion chamber has to be increased, making it impossible to increase the compression ratio. Was.

Furthermore, in the latter case, since the directions of the intake valves facing the combustion chamber are reversed, the area of the combustion chamber becomes large and the thermal efficiency becomes low.

The present invention was made in view of the above-mentioned problems of the prior art, and its purpose is to improve the combustion chamber volume and combustion by optimizing the inclination of the intake valve and the position of the camshaft. The present invention aims to provide a high-output engine that can reduce the chamber area and increase the compression ratio and thermal efficiency.

[Means for Solving the Problems] In order to achieve the above object, the four-stroke engine of the present invention has the following features: is located between the intersection of the axis of the intermediate intake valve and the lower end surface of the valve and the intake side cylinder wall.

[Function] Because the vertical line of the axis of the intake camshaft is closer to the cylinder center than the intake side cylinder wall, the intake valve in the middle is of course
In particular, the angle between the axes of the intake valves on both sides and the cylinder axis can be kept small, and the vertical line of the axis of the intake camshaft is positioned closer to the center of the cylinder than the intersection of the axis of the middle intake valve and the lower end of the valve. On the other hand, since it is located on the outside, the intermediate intake valve and the intake valves on both sides are oriented in substantially the same direction with respect to the intake camshaft, thereby making it possible to reduce the area of the combustion chamber.

[Example] Embodiments of the invention will be described below with reference to the drawings.

The drawing shows an L cylinder of a 4-cycle engine, where a is the cylinder, b is the cylinder head, 1 is the intake passage, and 2 is the cylinder head.
is the exhaust passage.

A combustion chamber 3 is formed on the lower surface of the cylinder head b, and an intake passage 1 and an exhaust passage 2 are open therein.

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 that opens and closes the intake passage 1, and 6 is an exhaust valve that opens and closes the exhaust passage 2.

These intake valves 5 and exhaust valves 6 have umbrella portions at their lower ends facing the combustion chamber 3 and corresponding to the openings of the intake passage 1 and the exhaust passage 20, respectively, and their middle portions are connected to the cylinder head b via kites 5a and 6a. It is slidably supported on the wall.

7.8 is connected to the upper end of the valves 5 and 6 or is attached to the lid.
”C is available, both valves 5 and 6 are connected via this lifter 7.8.
is the corresponding camshaft 9 directly above it. 10, and is adapted to be moved WJl by the shafts 9 and 10.

11 and 12 are springs that bias the intake valve 5 and the exhaust valve 6 in the valve-closing direction.

On the other hand, the cam shaft 9.10 is connected to the cam carrier 13 and the cam cap 14.1 above the cylinder spatula F'b.
5, it is rotatably held.

16 is the camshaft 9.10 and the cam cap 14.15
This is a cover that covers the cam carrier 13 and is connected to the upper end of the cam carrier 13.

This four-stroke engine is provided with three intake valves 5 and two electric pulps 6 per cylinder in order to improve its output performance.

Further, the arrangement structure of the intake valves 5 is such that the middle intake valve faces the combustion chamber 3 with a smaller inclination with respect to the axis 1+ of the cylinder a than the intake valves on both sides.

That is, if the inclination angle of the middle intake valve 5 is α1, and the inclination angle of the intake valves 5 on both sides is α2, then α1<α2.

Furthermore, the intake valves 5 each have their own axis 12 or camshaft 9.
It passes through the axis 01 of.

As shown in FIG. 4, in the intermediate intake valve 5, the vertical line 16 of the axis of the intake camshaft in a plane passing through the axis of the intermediate intake valve 5 and perpendicular to the intake camshaft 1) It is arranged at a point A between the intersection point 51) of the valve axis and the lower end surface of the valve and the intake side cylinder wall a.

In this way, since the vertical line 16 of the axis of the intake camshaft is closer to the cylinder center than the intake side cylinder a wall, the angle α1. α2 can be kept small, and as a result, the volume of the combustion chamber can be reduced and the compression ratio can be increased. In addition, since the vertical line 16 of the axis of the intake camshaft is located at the center of the cylinder and on the outside of the intersection 5b of the axis of the middle intake valve and the lower end surface of the valve, the intake cams of the middle intake valve and the intake valves on both sides The directions with respect to the axis are substantially the same, thereby making it possible to reduce the area of the combustion chamber and increase thermal efficiency.

Further, as shown in FIG. 4, a horizontal wall 17 facing the cylinder is provided on the lower surface of the cylinder head on the outside of the intermediate intake valve.
If this occurs, a strong squish will occur around the intermediate intake valve, greatly promoting combustion in the combustion chamber. Also, 1st. /1 As shown in Figure 1, the middle intake valve faces the combustion chamber 3 with a smaller inclination with respect to the axis 1+ of cylinder a than the intake valves on both sides, and the upper end 5c of each intake valve 5 is connected to the cylinder bore. Since the piston is located inward from the extension line of the piston, the intermediate intake valve becomes close to vertical, and the distance between the top surface of the piston and the bottom surface of the intake valve becomes narrower, which also promotes the occurrence of squish. In addition, since the intake valves on both sides have a larger inclination with respect to the axis 11 of the cylinder than the intake valve in the middle, the area of the intake valve can be increased, and intake efficiency is improved.

On the other hand, two exhaust valves 6 are provided, and are arranged in the combustion chamber 3 on a line 14 that is parallel to a center line 13 that passes through the center of the combustion chamber 3 and is parallel to the camshaft.

Further, the axes 15 of the exhaust valves 6 each pass through the axis 02 of the camshaft 10, and the inclination angle α3 of the cylinder a with respect to the axis 11 is set to be equal.

Since there are two exhaust valves 6, they will not interfere with each other even if they are arranged in series in the combustion chamber 3, and as a means to connect them to the camshaft 1O, a new device other than the lifter 8 is used. do not need.

In the above embodiment, two exhaust valves 6 are provided, but the exhaust valve 6 also has the intake valve 5.
It is also possible to provide three if the same arrangement structure is used.

In addition, since the diameter d of the intake valve 5 is smaller than the diameter d of the exhaust valve 6, and the intake valves 5 on both sides are arranged so as to intersect with the center line I3, they interfere with the spark plug. The intake valve 5 can be moved closer to the center of the combustion chamber 3 without causing any damage, and it is advantageous to provide the vertical line 16 of the axis 01 of the intake camshaft closer to the center of the cylinder a than the wall of the cylinder a on the intake side.

[Effects of the Invention] In this invention, each cylinder has three intake valves and a plurality of exhaust valves, each of which is driven by a camshaft above the intake valve, and the middle intake valve among the intake valves is driven by a camshaft on both sides. Since this is an engine that faces the combustion chamber with a smaller inclination to the cylinder axis than the intake valves of the previous model, it is possible to arrange the three intake valves without interfering with each other, and it is also possible to arrange the three intake valves without interfering with each other. Since the vertical line of the shaft center is closer to the center of the cylinder than the intake side cylinder wall, the angle between the cylinder axis and the intake valves on both sides, as well as the intermediate intake valve, can be kept small, resulting in a reduction in combustion chamber volume. can be made smaller to increase the compression ratio.

Also, since the vertical line of the axis of the intake camshaft is located on the outside of the center of the cylinder from the intersection of the axis of the intermediate intake valve and the lower end surface of the valve, the orientation of the intermediate intake valve and the intake valves on both sides with respect to the intake camshaft is are in substantially the same direction, thereby making it possible to reduce the area of the combustion chamber and, as a result, increase thermal efficiency.

Therefore, according to the present invention, a high output engine can be obtained.

[Brief explanation of the drawing]

1 is a longitudinal sectional view of an embodiment of an engine according to the present invention, FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1, and FIG. 3 is a sectional view taken along the line m-III in FIG. FIG. 4 shows a sectional view taken along the line rV-IV in FIG. 2. a...Cylinder, b...Cylinder head, 1...
Intake passage, 2... Exhaust passage, 3... Combustion chamber, 5...
・Intake valve, 6... IJF air valve, 5b... Intersection of the axis of the intake valve and the lower end surface of the valve, 9, lO... Camshaft, 1B... Axis of the cylinder, 1... Intake valve axis,
16...Plumb line of the axis of the intake camshaft, 0...Axis of the intake camshaft, αB...# inclination angle of the middle intake valve, α2...Inclination angle of the intake valves on both sides . Patent applicant: Yamaha Motor 81 Co., Ltd. Agent: Patent attorney Art supplies: Masao Figure 1 Figure 2

Claims (1)

[Claims] Each cylinder has three intake valves and a plurality of exhaust valves, each of which is driven by a camshaft above the intake valve, and the middle intake valve among the intake valves is positioned relative to the axis of the cylinder relative to the intake valves on both sides. In a four-stroke engine that faces the combustion chamber with a small inclination, the vertical line of the axis of the intake camshaft in a plane passing through the axis of the intermediate intake valve and orthogonal to the intake camshaft is the axis of the intermediate intake valve. A 4-cycle engine characterized by being located between the intersection of the valve axis and the lower end surface of the valve and the intake side cylinder wall.