JP3225299B2 - Multi-valve 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 multi-valve engine having an intake valve and an exhaust valve for opening and closing respective openings of a plurality of intake passages and exhaust passages.

[0002]

2. Description of the Related Art For example, in a multi-valve engine mounted on a motorcycle, a combustion chamber is formed at the head of a piston provided in a cylinder, and an ignition plug is arranged so as to face the center of the combustion chamber. A plurality of intake passages and an exhaust passage formed in communication with the combustion chamber; and an intake valve and an exhaust valve for opening and closing respective openings of the plurality of intake passages and the exhaust passage. At least one of the three valves of the same type is arranged in a semicircle around the spark plug with three valves being arranged at the center, and the axis of the valve located at the center and the axis of the valve located on both sides thereof are positioned with respect to the center of the bore of the cylinder. Some are set at different angles.

[0003]

In such a multi-valve engine, when the head of the piston is raised, the volume of the combustion chamber is reduced, and the air-fuel mixture is highly compressed, so that a high output can be obtained. Raise the piston head like
It is necessary to form a recess on the surface of the piston facing the valve in order to avoid interference with the valve.

[0004] In particular, at least one of the intake valve and the exhaust valve of the same type is disclosed in Japanese Patent Laid-Open No. 1-18 / 1989.
As disclosed in Japanese Patent Publication No. 2524, a valve located at the center by forming a recess in the head of the piston so that the three valves do not interfere with the valve arranged in a semicircle around the spark plug. Since the convex portion is left between the concave portion for the valve and the concave portion for the valve located on both sides of the concave portion, the flame may not be smoothly transmitted in the combustion chamber, and the combustion efficiency may be reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a multi-valve engine in which a combustion chamber is made smaller to increase a compression ratio, and flame propagation in the combustion chamber is made smooth to improve combustion efficiency. The purpose is.

[0006]

According to the present invention, a combustion chamber is formed at the head of a piston provided in a cylinder, and an ignition plug is provided so as to face the center of the combustion chamber. A plurality of intake passages and exhaust passages are formed in communication with the combustion chamber and are provided with an intake valve and an exhaust valve for opening and closing respective openings of the plurality of intake passages and the exhaust passage. Alternatively, at least one of the exhaust valves of the same type is disposed in a semicircular position around the ignition plug with three valves of the same type, and the center of the valve and the axes of the valves located on both sides thereof are the cylinder. In a multi-valve engine set at different angles with respect to the bore center of the piston, the head of the piston is formed such that the central apex of the head is higher than the peripheral edge of the head, and A portion facing the three valves,
A surface corresponding to the central valve and a surface corresponding to the two-sided valve are formed by two surfaces, and a portion between the surface corresponding to the central valve and the surface corresponding to the two-sided valve is a surface corresponding to the central valve. It is characterized by being formed by extending, and the switching portion between the two surfaces is located near the outer periphery of the surface corresponding to the double-sided valve.

[0007]

According to the present invention, the central apex of the head of the piston is formed higher than the peripheral edge of the head to reduce the size of the combustion chamber, thereby increasing the compression ratio and obtaining high output.

Further, a portion of the head portion facing the three valves of the same kind is formed of two surfaces, a surface corresponding to the central valve and a surface corresponding to both side valves, and corresponds to the central valve located at the center. There is no projection between the surface that faces the corresponding valve and the surfaces corresponding to the valves on both sides, and the head of the piston is flat, so that flame propagation in the combustion chamber is performed smoothly and combustion efficiency is improved. improves.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. 1 is a cross-sectional view of a multi-valve engine, FIG. 2 is a side view of a piston, FIG. 3 is a plan view of the piston, FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 3, and FIG. It is a side view.

The multi-valve engine is mounted on, for example, a motorcycle. A cylinder head 2 is mounted on a cylinder block 1 of the multi-valve engine. A valve case 200 is fixed to the cylinder head 2 with bolts 22.
Further, the head cover 3 is attached to the valve case 200, and the cylinder 4 is formed by these.

A piston 5 is fitted to the cylinder block 1 so as to be able to reciprocate.
The connecting rod 6 is connected to the crankshaft (not shown) via a pin 00, and a combustion chamber 7 is formed between the head 5 a of the piston 5 and the cylinder head 2. A spark plug 8 is attached to the cylinder head 2 so as to face the center of the combustion chamber 7.
Are formed, three intake passages 9 and two exhaust passages 10 are formed.

Further, one intake pipe 11 is connected to the cylinder head 2, and three intake passages 9 are connected to the intake pipe 11.
Are connected to each other, and two exhaust pipes 12 are connected to the opposite side of the cylinder head 2. Two exhaust passages 10 are independently connected to the respective exhaust pipes 12.

Each of the intake passage 9 and the exhaust passage 10 is open to the combustion chamber 7, and the opening 9a, 10a has an intake valve 13 and an exhaust valve for opening and closing the intake passage 9 and the exhaust passage 10, respectively. 14 are provided. The three intake valves 13 are arranged at semicircular positions around the ignition plug 8, and the axes of the centrally located valve and the valves located on both sides thereof are different from the bore center of the cylinder 4. The angle is set. Further, the two exhaust valves 14 are arranged symmetrically with respect to the ignition plug 8.

The valve stems 15 and 16 of the intake valve 13 and the exhaust valve 14 thus arranged are slidably supported by the cylinder head 2, and the valve stems 15 and 16 are suctioned by valve springs 17 and 18. It is urged in a direction to close the passage 9 and the exhaust passage 10. Valve lifters 19 and 20 are provided at the distal ends of the valve stems 15 and 16, and the valve lifters 19 and 20 are slidably supported by a valve bearing 21 of a valve case 200.

The valve bearing 21 has a pair of camshafts 2.
3 and 24 are arranged in the crankshaft direction, and the cam cap 2
5, 26 are rotatably supported. The valve lifter 19 of the intake valve 13 is pushed by the cam portion 23a of the camshaft 23 on the intake side, and the camshaft 24 on the exhaust side
The valve lifter 20 of the exhaust valve 14 is pushed by the cam portion 24a.

The piston 5 provided in the cylinder 4 has a central apex 5a1 of the head 5a formed higher than a peripheral edge 5a2. And the head 5a of the piston 5
The intake side portion facing the three intake valves 13 is formed of two surfaces, a surface 5a3 corresponding to the central valve and a surface 5a4 corresponding to both side valves, and these two surfaces are outward at a predetermined angle. It has a continuous flat surface that slopes toward it.

The portion 5a6 between the surface 5a3 corresponding to the central valve and the surface 5a4 corresponding to the two-sided valve is formed by extending the surface 5a3 corresponding to the central valve, and the surface 5a3 corresponding to the central valve and A switching portion 5a7 of the two surfaces 5a4 corresponding to the two-sided valve is formed in a step, and the switching portion 5a7 is located near the outer periphery of the surface 5a4 corresponding to the two-sided valve.

The exhaust-side portion of the head 5a of the piston 5 opposed to the two exhaust valves 14 is formed of a continuous surface 5a5 corresponding to each valve.
5 also has a continuous flat surface inclined outward at a predetermined angle.

A ridge 5a at the top of the head 5a of the piston 5 on the intake side facing the three intake valves 13 and the exhaust side facing the two exhaust valves 14.
Reference numeral 8 extends in the diameter direction of the head 5a.

Further, the peripheral portion 5 of the head 5a of the piston 5
A squish area 27 is formed between a 2 and the cylinder block 2. The squish area 27 acts to concentrate the air-fuel mixture in the direction of the spark plug 8.

A piston pin insertion hole 28 for inserting the piston pin 100 is formed at a position between the intake side and the exhaust side of the head 5 a of the piston 5, and is formed on the upper outer periphery of the piston 5. A piston ring 30 is provided in the ring groove 29.

As described above, the central apex portion 5a1 of the head 5a of the piston 5 is formed higher than the peripheral edge portion 5a2, so that the combustion chamber 7 becomes smaller, thereby increasing the compression ratio and obtaining high output. it can. Further, a portion facing three intake valves 13 of the same type is formed of two surfaces, a surface 5a3 corresponding to the central valve and a surface 5a4 corresponding to both side valves, and these are continuous flat surfaces. Therefore, the flame propagation in the combustion chamber 7 is performed smoothly, and the combustion efficiency is improved.

Although this embodiment is applied to a multi-valve engine having three intake valves, a multi-valve engine having three exhaust valves also faces the exhaust valve of the piston. The part can be formed and applied with two surfaces, a surface corresponding to the central valve and a surface corresponding to the double-sided valves.

[0024]

As described above, according to the present invention, the central apex of the head of the piston is formed higher than the peripheral edge of the head to reduce the size of the combustion chamber, thereby increasing the compression ratio. You can get the output.

Further, a portion of the head portion facing the three valves of the same type is formed of two surfaces, a surface corresponding to the central valve and a surface corresponding to both side valves, and corresponds to the central valve located at the center. There is no projection between the surface that faces the corresponding valve and the surfaces corresponding to the valves on both sides, and the head of the piston is flat, so that flame propagation in the combustion chamber is performed smoothly and combustion efficiency is improved. improves.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a multi-valve engine.

FIG. 2 is a side view of a piston.

FIG. 3 is a plan view of a piston.

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3;

FIG. 5 is a side view in which a part of a piston is broken.

[Explanation of symbols]

4 Cylinder 5 Piston 5a Head 5a1 Central apex 5a2 Peripheral edge 5a3 Surface corresponding to central valve 5a4 Surface corresponding to both side valves 5a6 Part between surface 5a3 corresponding to central valve and surface 5a4 corresponding to both side valves 5a7 Switching section 5a8 Top ridge 7 Combustion chamber 8 Spark plug 9 Intake passage 10 Exhaust passage 13 Intake valve 14 Exhaust valve

Claims (1)

(57) [Claims] A combustion chamber is formed at the head of a piston provided in a cylinder, an ignition plug is disposed so as to face a center portion of the combustion chamber, and a plurality of intake passages and a plurality of intake passages communicate with the combustion chamber. An exhaust passage is formed, and has an intake valve and an exhaust valve that open and close respective openings of the plurality of intake passages and the exhaust passage. At least one of the intake valve and the exhaust valve has three valves of the same type. A multi-valve engine which is arranged at a semicircular position with the spark plug as a center, and the center of the valve and the axes of the valves located on both sides thereof are set at different angles with respect to the bore center of the cylinder. In the head of the piston, a central vertex of the head is formed higher than a peripheral edge of the head, and a portion of the head opposed to the three valves has a surface corresponding to the central valve. And a surface corresponding to the central valve, and a portion between the surface corresponding to the central valve and the surface corresponding to the central valve is formed by extending the surface corresponding to the central valve. A multi-valve engine, characterized in that the switching portion between the two surfaces is located near the outer periphery of the surface corresponding to the double-sided valve.