JPH01257707A - Four-cycle engine - Google Patents

Abstract

PURPOSE:To aim at improvement of a compression ratio by arranging the springs of intake valves on both sides of an ignition plug in the intake valves to overlap a plug hole. CONSTITUTION:The diameter of the shades of intake valves 5 at both sides of an ignition plug in three intake valves is formed smaller than that of the shade of an exhaust valve 6. The springs 11' of both sides intake valves 5 are arranged to overlap a plug bole 17 viewing from the direction of a cam shaft 9. Accordingly, an angle between the axial line of an intake valve and that of a cylinder can be restrained in small, the volume of a combustion chamber can be heed small so that compression ratio can be increased.

Description

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

[Prior Art] One cylinder has three intake valves and three exhaust valves, and a spark plug is provided in the center of the cylinder, and the middle intake valve is located closer to the axis of the cylinder than the intake valves on both sides. For example, an engine that faces the combustion chamber by reducing the inclination to the combustion chamber is disclosed in British Patent No. 296
It is known as shown in the specification of No. 125.

Engines with three intake valves and two exhaust valves per cylinder are also known, as shown in British Patent No. 687,528.

[Problems to be Solved by the Invention] Incidentally, in the former known engine, three intake valves per cylinder are arranged using approximately 1/2 of the cylinder. The intake valve part and exhaust valve part are widely opened in a V-shape and are arranged independently, with the spark plug in the center as the center.
As the angle between the axes of the three intake valves and the cylinder axis increases, the combustion chamber volume cannot be increased, and the compression ratio cannot be increased. In addition, in the latter engine, the diameter of the intake valve and the diameter of the exhaust valve are the same, so the spark plaque and the intake valves on both sides are close to each other, so the intake valves on both sides are biased in the closing direction. If the splinter is arranged so that it overlaps with the plaque ball when viewed in the direction of the camshaft, the spark plaque will inevitably become smaller, which makes it unsuitable for obtaining a high-output engine. had.

This invention has been made in view of the problems of the prior art, and its purpose is to improve the inclination, umbrella diameter, and camshaft of the intake valve.

The present invention aims to provide a high-output engine that can reduce the volume of the combustion chamber and increase the compression ratio by optimizing the position of the splinter and the like.

[Means for Solving the Problems] In order to achieve the second object, the four-stroke engine of the present invention has the following features: The diameter of the intake valves on both sides is made smaller than the diameter of the exhaust valve. The splinter, which is biased in the closing direction, is arranged so as to overlap the plaque ball when viewed in the direction of the camshaft.

[Function] Since the diameters of the intake valves on both sides are smaller than the diameters of the exhaust valves, the intake valves on both sides can be placed away from the plaque ball in the direction of the camshaft. Since the printer is placed so that it overlaps with the plaque hole when viewed in the direction of the camshaft, the angle between the three intake valve axes and the cylinder axis can be kept small, making it possible to make the combustion chamber more compact.
A relatively large-capacity spark plaque can be placed to obtain a high-power engine.

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

-:3- The drawing shows one 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 plaque, 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 exhaust passage 2, respectively, and their middle portions are connected to the cylinder head 1) through guides 5a and 6a. It is slidably supported on the wall.

Reference numeral 7.8 denotes a lid connected to the upper ends of the valves 5, 6, and via this lifter 7.8, both valves 5.6 are connected to the corresponding camshafts 9, 10 directly above the lifters 7.8. 9,10
It is designed to be driven by

11, 11' and 12 are splinters that urge the intake valve 5 and the exhaust parflo in the valve closing direction.

On the other hand, the cam shafts 9 and 10 are connected to a cam carrier 13 and a cam cap 14, 15 above the cylinder head 1].
It is rotatably held through the

16 is the cam shaft 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.

In order to improve its output performance, this four-stroke engine is provided with three intake valves 5 and two exhaust valves per cylinder.

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 11 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, each of the intake valves 5 has its axis 12 aligned with the camshaft 9.
It passes through the axis 0+ of .

As shown in FIGS. 1 and 4, each lifter 7 of the intake valve 5 is located on the outer surface of a plaque hole 17 on the side of the intake camshaft 9, which is provided with a screw hole 4 for attaching a spark plaque. It is slidably kited by a kite portion 18 that is integrally formed with the cam carrier 13 that constitutes a part of the plaque hole 17. Moreover, the springs 11' that bias the intake valves 5 on both sides in the closing direction are the first springs 11'.
As shown in the figure, it is arranged so as to overlap with the plug hole 17 when viewed in the direction of the camshaft 9.

In this way, each lifter 7 of the intake valve 5 is accurately kited by the kite portion 18 formed integrally with the cam carrier 13, so that its operation is reliable, and the lifter 7 of the intermediate intake valve 5 is fitted into the plug hole. 17, and the springs 11 of the intake valves 5 on both sides
Since it is arranged so that it overlaps with the plug hole 17 when viewed in the camshaft direction, the angle between the axes of the three intake valves 5 and the cylinder axis 11 can be kept small. The combustion chamber can be installed closer to the center, making the combustion chamber more compact.

Furthermore, as shown in FIG. 2, since the diameter d of the intake valves 5 on both sides is made smaller than the diameter d of the exhaust valve 6, the intake valves 5 on both sides are placed away from the plug hole 17 in the direction of the camshaft 9. This makes it possible to use a large-capacity spark plug while increasing the overlap between the spring 11' and the plug hole 17.

In addition, as shown in FIGS. 1 and 4, the cam carrier 13, in which the guide portion 18 for guiding each lifter 7 of the intake valve 5 is integrally formed, is configured separately from the cylinder head b. 5 to the cylinder J\tb, the work of compressing the spring 11.11' can be done by removing the cam carrier 13. Since there are three intake valves 5, the diameter can be reduced, and the lid 7 can be compressed.
Since the guide portion 18 can be removed for work, the work efficiency is improved. Moreover, since the guide portion 18 of the lifter 7 of the full intake valve 5 is integrally provided on the cam carrier 13, when the cam carrier 13 is removed, the upper part of the valve spring 11, 11' is largely opened, which further improves the workability. improves.

On the other hand, two exhaust valves 6 are provided, and are arranged on a line 14 parallel to the center line 13 within the combustion chamber 3.

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 for connecting them to the camshaft 10, a new device other than the lifter 8 is used. do not need.

In this embodiment, the cam noses 19 of the cams that open and close the intake valves 5 on both sides are aligned with the axis 01 of the intake cam 9 with respect to the cam nose 20 of the cam that opens and closes the intermediate intake valve 5.
The opening and closing timings of the three intake valves 5 can be synchronized by arranging them at a position slightly rotated in one direction (clockwise in FIG. 1.4) about the center.

[Effects of the Invention] In the present invention, each cylinder has three intake valves and two exhaust valves, and includes a spark plug arranged in the center of the cylinder and surrounded by a plug hole, Since this engine has a valve facing the combustion chamber with a smaller inclination to the cylinder axis than the intake valves on either side, it goes without saying that the three intake valves can be arranged without interfering with each other. In such an engine, the springs that bias the intake valves on both sides in the closing direction are arranged so that they overlap with the plug holes when viewed in the direction of the camshaft, so the angle between the axes of the three intake valves and the cylinder axis is reduced. As a result, the combustion chamber can be made compact and the compression ratio can be increased, resulting in an engine with overall high output. Moreover, in this case, the diameter of the intake valves on both sides was made smaller than the diameter of the exhaust valve, so the intake valves on both sides could be placed away from the plug hole in the camshaft direction, reducing the overlap between the spring and the plug hole. It is possible to install a large-capacity ignition plaque suitable for high-output engines while increasing the size of the engine.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of an engine according to the present invention;
Figure 2 is a sectional view taken along the line ■-■ in Figure 1, and Figure 3 is a cross-sectional view taken along the line ■ in Figure 1.
4 shows a sectional view taken along the line IV--IV in FIG. 2. a... Cylinder, b... Cylinder head, d... Cap diameter of both intake valves, D... Cap diameter of exhaust valve, 1... Intake passage, 2... Exhaust passage, 3 ... Combustion chamber, 4... Screw hole for installing spark plug, 5... Intake valve, 6... Exhaust valve, 9.10... Camshaft, 11.11'... Spring, 17...Plug hole, 11...Axis of cylinder, 12...Axis of intake valve, αbi...Inclination angle of middle intake valve, α2...Inclination angle of intake valves on both sides. Patent applicant Yamaha Motor Co., Ltd. agent Patent attorney Art supplies Mikio r->

Claims (1)

[Claims] Each cylinder has three intake valves and two exhaust valves, and includes a spark plug arranged in the center of the cylinder and surrounded by a plug hole, with the middle intake valve of the intake valves being lower than the intake valves on both sides. In a four-stroke engine in which the inclination of the cylinder with respect to the axis is reduced so that it faces the combustion chamber, the umbrella diameter of the intake valves on both sides is made smaller than the umbrella diameter of the exhaust valve, and the intake valves on both sides are moved in the closing direction. A four-stroke engine characterized by a biasing spring arranged so as to overlap the plug hole when viewed in the direction of the camshaft.