JP2603801Y2 - 4-cycle engine for vehicles - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder head structure for a four-cycle engine for a vehicle, and more particularly to a cooling air guide structure for a cylinder head of an air-cooled four-cycle engine such as a motorcycle or a four-wheeled vehicle.

[0002]

2. Description of the Related Art In recent years, for a four-cycle engine for a vehicle,
To take advantage of the low flow resistance of intake and exhaust,
A multi-valve engine (e.g., 4) in which a plurality of exhaust valves and intake valves (e.g., two) are provided for each cylinder.
Valve engine). In an air-cooled four-stroke engine for a vehicle, a spark plug, which tends to be high in temperature, and a spark plug located in the center of the cylinder head from the front in the vehicle traveling direction are provided on the cylinder head in order to prevent a temperature rise near the exhaust valve and the exhaust port. It has been proposed to provide ventilation holes leading to the vicinity. A document disclosing such a conventional technique is, for example, Japanese Patent Publication No. 4-33980.

[0003]

By the way, a plurality of exhaust valves and a plurality of intake valves are arranged side by side with respect to the traveling direction of the vehicle and one cylinder, and each of the plurality of exhaust ports and the plurality of intake ports is connected to one port. In the case of an air-cooled four-stroke engine configured to be integrated into a cylinder, the concept of providing ventilation holes between cylinders existed in the past, because the inside of the cylinder head had an intensive and dense structure. It is difficult to direct the cooling air to the central spark plug. Further, even when a ventilation hole is formed between the valves, the camshaft disposed immediately above the combustion chamber interferes (obstructs), so that a uniform cross-section having a sufficient flow path cross-sectional area is provided. Can not form a ventilation hole,
Therefore, there is a technical problem that stagnation is easily generated in the cooling air, and sufficient cooling efficiency cannot be obtained.

The present invention has been made in view of such prior art, and an object of the present invention is to pass through between exhaust valves, near a spark plug at a central portion of a cylinder, and between intake valves, and in the rearward direction of the vehicle. In forming the ventilation hole communicating with the side, the cross-sectional shape and the cross-sectional area of the ventilation hole can be made substantially constant from the inlet to the outlet and relatively large. An object of the present invention is to provide an air-cooled multi-valve engine for a vehicle that can improve the cooling efficiency of a vehicle.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a plurality of exhaust valves arranged laterally in front of a cylinder and a plurality of intake valves arranged rearward of a cylinder. A four-stroke engine for a vehicle having a valve and
An exhaust-side camshaft arranged on the front side of the plurality of exhaust valves and on one side of the cylinder, and an intake-side camshaft arranged on the rear side of the plurality of intake valves and on one side of the cylinder. A plurality of exhaust ports and a plurality of intake ports formed for each cylinder are combined into one port, and a cylinder head is provided. A ventilation hole is formed which is formed between the exhaust valves from the front side in the vehicle traveling direction, the vicinity of the ignition plug at the center of the cylinder, and the space between the intake valves to the rear side in the vehicle traveling direction.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. Note that the same reference numerals denote the same or corresponding parts throughout the drawings. FIG. 1 is a plan view of a cylinder head of a four-cycle engine (air-cooled multi-valve engine) suitable for a vehicle to which the present invention is applied.
FIG. 2 is a longitudinal sectional view taken along line 2-2 in FIG. 1 and 2 show a two-cylinder four-valve engine in which two intake valves and two exhaust valves are provided for each cylinder.

1 and 2, two cylinders 1,
1, a cylinder head 2 having an intake passage 3 for each cylinder;
3 and exhaust passages 4 and 4, two intake valves 5, 5 and 2 are provided in the cylinder head 2 for each cylinder.
A plurality of exhaust valves 6, 6 are provided. Each intake valve 5 and each exhaust valve 6 are urged in a valve closing direction by a valve spring 7 (FIG. 2). Since each cylinder has substantially the same configuration, one cylinder will be described in the following description unless otherwise specified.

In FIG. 2, reference numeral 21 denotes a cylinder;
2 denotes a piston fitted to the cylinder 21, and 23 denotes a head cover for sealing the cylinder head 2. 24 (FIG. 1) indicates a spark plug, and 25 (FIG. 2) indicates a combustion chamber. 1 and 2, rocker arm shafts 8, 8 are attached to the intake side and the exhaust side of the cylinder head 2 in parallel with each other, and a rocker arm 9 is rotatably fitted to each rocker arm shaft 8. I have.

Each rocker arm 9 has a valve drive arm 1
0 and the cam follower arm 11 are integrally formed.
In the illustrated example, two of the valve drive arms 10 are formed on each rocker arm 9 corresponding to the two intake valves 5 and 5 and the two exhaust valves 6 and 6. A roller 12 serving as a cam follower is rotatably supported at the tip of the cam follower arm 11. The valve mechanism such as the rocker arm 9 and a cam shaft 13 described later is disposed in a rocker arm chamber 19 formed by the upper side of the cylinder head 2 and the head cover 23.

The camshaft 1 is located below the rocker arm shafts 8, 8 of the cylinder head 2 (on the side of the combustion chamber 25).
3, 13 are pivotally supported. At the center of the cylinder head 2 (between the cylinders 1 and 1), two side walls 14 and 14 are formed at a predetermined interval, and are located on the intake side (left side in FIG.
(Right side) and the exhaust-side camshafts 13, 13 are rotatably supported through both side wall portions 14, 14. A transmission member (driven sprocket in the illustrated example) 15 for driving the camshaft is provided at an intermediate portion of each camshaft 13.
Are fixed integrally.

A transmission mechanism (in this embodiment, a chain transmission mechanism) for driving each camshaft 13 includes a driving sprocket (not shown) fixed to a crankshaft (not shown), the driven sprocket 15, It consists of a chain 27 stretched between sprockets. The transmission mechanism for driving the camshaft includes the side wall portions 14, 14.
It is arranged in a cavity (a chain tunnel when a chain is used) 28 formed therebetween.

Each camshaft 13 has a cam portion 1 which comes into contact with a cam follower (roller) 12 of a corresponding rocker arm 9.
6 are formed. That is, each cam shaft 13 is rotatably supported by two side wall portions 14 formed at a predetermined interval and is rotatably supported.
Each cam portion 16 for each cylinder 1, 1 is provided at both end portions extending from
16 are formed. As shown in the figure, each cam portion 16 is provided near a side wall portion 14 avoiding the intake passage 3 and the exhaust passage 4 of the cylinder head 2, that is, as shown in FIG. It is provided at a position adjacent to the transmission member 15. In the illustrated example, the rocker arm 9 is positioned in the thrust direction by the elastic force of a spring 18 mounted on the rocker arm shaft 8.

In the four-cycle engine for a vehicle having the above-described structure, the exhaust side having a larger heat load has a higher temperature than the intake side (the left side in FIG. 1 and the right side in FIG. 2). It is mounted with the exhaust side facing forward in the vehicle traveling direction so as to blow cooling air (running air). Therefore, an arrow F in FIGS. 1 and 2 indicates a flow direction of a traveling wind (cooling wind) when the illustrated engine is mounted on a vehicle.

FIG. 3 is a plan view of a cylinder head of a first embodiment of a four-cycle engine (air-cooled multi-valve engine) for a vehicle to which the present invention is applied, and FIG. 4 is taken along line 4-4 in FIG. FIG. 5 is a vertical sectional view taken along the line 5--5 in FIG.
FIG. 5 is a longitudinal sectional view along 5. In each of the embodiments described below, the present invention is applied to the engine described with reference to FIGS. 1 and 2. In each of the embodiments, components other than those described below have the same configurations and configurations as those in FIGS. The arrangement is made.

In FIG. 3 to FIG. 5, the intake passage 3 of each cylinder 1 of the cylinder head 2 is controlled to open and close at its combustion chamber side by two intake valves 5, 5 arranged side by side. And a single intake port 32 at the surface side portion of the cylinder head 2.
It is formed with. That is, the plurality of intake ports 31 corresponding to the plurality of intake valves 5 formed per cylinder are:
The ports are combined into one port 32 in the cylinder head 2.

Similarly, one exhaust passage 4 of each cylinder of the cylinder head 2 is also opened and closed at its combustion chamber side by two exhaust valves 5, 5 arranged side by side. It is formed by exhaust ports 33, 33, and is formed by one exhaust port 34 on the surface side portion of the cylinder head 2. That is, also in the exhaust passage 4, the plurality of exhaust ports 33 corresponding to the plurality of exhaust valves 5 formed per cylinder are combined into one port 34 in the cylinder head 2. Arrows F in FIGS. 3 to 5 indicate the flow direction of the traveling wind (cooling wind) of the vehicle equipped with the engine, as in FIGS. 1 and 2.

In FIGS. 3 and 4, the portion of each cylinder 1 of the cylinder head 2 extends from the front side in the vehicle traveling direction to the spark plug 24 (or its vicinity) at the center of the cylinder through the space between the exhaust valves 6 and 6. A ventilation hole (first half) 35 is formed. Further, on an extension of the ventilation hole 35, a ventilation hole (second half) 36 that passes through the space between the intake valves 5 and 5 and passes rearward in the vehicle traveling direction of the cylinder head 2. Are formed.

These ventilation holes 35 and 36 are formed between the exhaust passage 4 and the intake passage 3 and the rocker arm chamber 19 as shown in FIG. As shown in FIG. 3, the passage cross section of each of the ventilation holes 35 and 36 is enlarged in a smoothly curved state at the front end opening and the rear end opening of the cylinder head 2, and between the exhaust valves 6, 6 and The portion passing between the intake valves 5 has a relatively narrow shape.

With the configuration shown in FIGS. 3 to 5, a plurality (two) of exhaust valves 6, 6 and a plurality (two) of intake valves 5, 5 are arranged laterally in the vehicle traveling direction and per cylinder. A four-stroke engine for a vehicle, in which a plurality of (two) exhaust ports 33, 33 and a plurality of (two) intake ports 31, 31 formed per cylinder are connected to one port 34, 32, respectively. A ventilation hole 35 is formed through the cylinder head 2 from the front side in the vehicle traveling direction to the rear side in the vehicle traveling direction through between the exhaust valves 6 and 6, near the ignition plug 24 in the center of the cylinder, and between the intake valves 5 and 5. In forming 36, the exhaust-side camshaft 13 arranged in front of the plurality of exhaust valves 6, 6 and side by side on one side of the cylinder and side by side on the rear side of the plurality of intake valves 5, 5 and on one side of the cylinder. Camshaft 13 on the intake side Vehicle 4, characterized in that provided
A cycle engine is provided.

With such a configuration, ventilation holes 35, 36 communicating between the exhaust valves 6, 6, near the spark plug 24 in the center of the cylinder, and between the intake valves 5, 5, and passing rearward in the vehicle traveling direction. When providing the ventilation holes, the cross-sectional shape and the cross-sectional area of the ventilation holes can be made substantially large from the inlet to the outlet, and the flow of the cooling air in the ventilation holes 35 and 36 can be made smooth to improve the cooling efficiency of the engine. , An air-cooled four-stroke engine for a vehicle can be obtained.

In the above embodiment, the case of a two-cylinder engine is exemplified. However, the present invention can be similarly applied to a single-cylinder engine and a multi-cylinder engine having three or more cylinders, and the same operation and effect can be obtained. It is. Further, in the above embodiment, the case where two intake valves and two exhaust valves are provided per cylinder is exemplified. However, the present invention provides an engine provided with three or more intake valves and three or more exhaust valves per cylinder. And the same effect can be obtained.

Further, in the above embodiment, the case where the chain transmission mechanism is used for driving the camshaft is illustrated, but the present invention uses another transmission type transmission mechanism such as a gear transmission mechanism or a belt transmission mechanism. In this case, the same effect can be obtained.

[0023]

As is apparent from the above description, according to the present invention, a plurality of exhaust valves are disposed laterally to the vehicle traveling direction and in front of the cylinder and a plurality of intake valves disposed in the rear of the cylinder. A four-stroke engine for a vehicle having a valve and an exhaust-side camshaft arranged in front of the plurality of exhaust valves and side by side on one side of the cylinder; and on a rear side of the plurality of intake valves and on one side of the cylinder. A plurality of exhaust ports and a plurality of intake ports formed per cylinder, each including a camshaft on the intake side arranged side by side, and a spark plug arranged so that an electrode faces substantially in the center of the combustion chamber. Are combined into one port, and a ventilation hole is formed in the cylinder head between the exhaust valve from the front side in the vehicle traveling direction, near the ignition plug in the center of the cylinder, and between the intake valves, and communicates to the rear side in the vehicle traveling direction. Configuration In forming the ventilation holes communicating between the exhaust valves, near the ignition plug in the center of the cylinder, and between the intake valves, and leading to the rear side in the vehicle traveling direction, the cross-sectional shape and cross-sectional area of the ventilation holes are changed from the inlet to the outlet. Provided is a four-stroke engine for a vehicle, which can be made substantially constant and relatively large, and can smoothen the flow of cooling air in a ventilation hole and improve the cooling efficiency of the engine.

[Brief description of the drawings]

FIG. 1 is a plan view from above a cylinder head of a four-cycle engine for a vehicle suitable for applying the present invention.

FIG. 2 is a longitudinal sectional view taken along line 2-2 in FIG.

FIG. 3 is a plan view of one embodiment of a four-cycle engine for a vehicle to which the present invention is applied, as viewed from above a cylinder head.

FIG. 4 is a longitudinal sectional view taken along line 4-4 in FIG.

FIG. 5 is a longitudinal sectional view taken along line 5-5 in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder 2 Cylinder head 3 Intake passage 4 Exhaust passage 5 Intake valve 6 Exhaust valve 7 Valve spring 8 Rocker arm shaft 9 Rocker arm 13 Camshaft 15 Transmission member (sprocket) 16 Cam part 19 Rocker arm chamber 21 Cylinder 22 Piston 23 Head cover 24 Spark plug 25 Combustion chamber 31 Intake port 32 Intake port 33 Exhaust port 34 Exhaust port 35 Ventilation hole 36 Ventilation hole F Flow direction of running wind (cooling wind)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02F 1/32 F01P 1/02 F01P 1/08 F01P 1/10

Claims (1)

(57) [Scope of request for utility model registration] 1. A four-cycle engine for a vehicle, comprising: a plurality of exhaust valves disposed laterally to a vehicle traveling direction and in front of a cylinder; and a plurality of intake valves disposed in a rear side of a cylinder. An exhaust-side camshaft arranged in front of the exhaust valve and side-by-side on one side of the cylinder; an intake-side camshaft arranged behind the plurality of intake valves and side-by-side on one side of the cylinder; and a combustion chamber. A spark plug disposed so that the electrode faces substantially at the center of the vehicle. A plurality of exhaust ports and a plurality of intake ports formed per cylinder are combined into one port, and the vehicle travels to the cylinder head. A four-stroke engine for a vehicle, wherein a ventilation hole is formed from the front side to the rear side in the vehicle traveling direction between the exhaust valves, near the ignition plug in the center of the cylinder, and between the intake valves.