JPH0121161Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is a water-cooled engine mainly used for motorcycles, in which each cylinder is arranged in the front and rear, and an integral cylinder head for both cylinders is provided. Regarding the two-cylinder engine.

(Prior Art and Problems) A cooling water outlet is formed on the upper surface of the cylinder head, and is connected to a radiator in front via a cooling water pipe or the like. This makes it difficult to arrange an air cleaner or the like above the cylinder head. In addition, the cylinder head tightening bolts must be placed away from the cooling water outlet, which results in irregular spacing between each head tightening bolt, making the cylinder head tightening strength unstable.
This may cause pressure leaks.

(Purpose of the invention) (1) To enable easy placement of air cleaners, etc. above the cylinder head.

(2) Enable cylinder head tightening bolts to be arranged regularly.

(3) Ensure that the temperature of the cooling water in both cylinders is maintained evenly.

(Structure of the invention) In a water-cooled two-cylinder engine in which each cylinder is arranged in parallel in the front and rear and is equipped with an integrated cylinder head for both cylinders, the engine is located between the two cylinders in the longitudinal direction, and is located on either the left or right side of the cylinder head. A cooling water outlet common to both cylinders is formed integrally with the cylinder head on that side, and the cooling water outlet is made to protrude in a substantially horizontal lateral direction, and the cooling water thermostat is oriented laterally and between both cylinders. It is arranged at a position shifted toward the cooling water outlet side and connected to the cooling water outlet section.

(Embodiment) Fig. 1 is a left side partial view of a two-wheeled motor vehicle equipped with a two-cylinder engine according to the present invention. A water-cooled two-cylinder engine 4 is mounted above the down tube 3. Both cylinders 5 and 6 of the engine 4 are arranged in front and behind each other, and are tilted so that their upper ends are located upwardly in the front. An integral cylinder head 8 for both cylinders 5 and 6 is fixed to the upper ends of the cylinders 5 and 6, and an air cleaner 10 is disposed above the cylinder head 8 (on the upper front side).

A radiator 11 is disposed in front of the engine 4, and its lower end supply portion 11a is connected to a cooling water pump 13 via a cooling water supply pipe 12. The cooling water pump 13 is fixed to the side surface of the crankcase 15, and the outlet portion of the pump 13 communicates with the cooling water passage of each cylinder 5, 6 via each cooling water pipe 16, 17. The upper end return portion 11b of the radiator 11 is a cooling water return pipe 18.
It is connected to the cooling water outlet section 19 of the cylinder head 8 via a. The pipe 18 extends rearward on the left side of the tube 3.

FIG. 2 shows an enlarged view of the cylinder head 8 in the direction of the arrows in FIG. 1, and in this FIG. It is formed almost horizontally. Inside the outlet section 19, a thermostat 20 is arranged horizontally as is clear from the figure.
The thermostat 20 has its flange portion 20a clamped between the mounting seat 21 of the outlet portion 19 and the cap 22. That is, the thermostat 20 is located between the two cylinders and shifted toward the cooling water outlet side. The cap 22 is fixed to the left end surface of the outlet portion 19 by a plurality of bolts 23 and extends forward, with a front end connected to the cooling water return pipe 18. Reference numeral 26 denotes stud holes for the front cylinders 5, and five stud holes are formed at equal intervals in the circumferential direction. 27 is a stud hole for rear cylinder 6,
Five pieces are formed at equal intervals in the circumferential direction.
A head tightening bolt is inserted into each stud hole 26, 27 from the cylinder 5, 6 side, and the cylinder head 8 is tightened to the cylinder 5, 6 by a nut. Reference numeral 29 denotes an air vent hole, which communicates with the cooling water jacket 32 shown in FIG.

In FIG. 3, which shows the - cross section of FIG.
The cooling water jacket 31 in the front part and the cooling water jacket 32 in the rear part are connected through the cooling water jacket 31 and the cooling water jacket 32 in the rear part. Each cooling water jacket 31, 32 communicates with the cooling water passage of each cylinder 5, 6, respectively.

(Cooling water circulation route) Cooling water flows from radiator 11 to pipe 1 in Figure 1.
2 into the pump 13, and the pump 13
The cooling water is supplied from the cooling water through pipes 16 and 17 to the cooling water passages in the cylinders 5 and 6, respectively. Each cylinder 5,
6 to the respective jackets 31, 32 in the cylinder head 8 of FIG. The outlet 19 leads to the radiator 11 in FIG. 1 via the thermostat 20 in FIG. 2, the cap 22 and the pipe 18.

(Another embodiment) A cooling water outlet is formed on the right side of the cylinder head.

(Effects of the invention) (1) Since the cooling water outlet is formed on the side of the cylinder head between both cylinders, a large space above the cylinder head can be taken up, and an air cleaner etc. can be installed above the head. They can be easily placed in close proximity.

To explain in detail, a cooling water outlet common to both cylinders is formed integrally with the cylinder head on either the left or right side of the cylinder head, which is an intermediate portion between the two cylinders in the longitudinal direction. It protrudes horizontally and the cooling water thermostat is placed horizontally and in a position shifted toward the cooling water outlet between both cylinders, so the cooling water return piping and thermostat are located above the cylinder head. There are no studs, etc., and a large space for arranging the air cleaner can be secured above the cylinder head.

(2) When installing a thermostat at the outlet, it can be easily installed from the side of the engine, and inspection and repair of the thermostat can also be easily performed from the side of the engine. This has particularly high practical value in motorcycles.

(3) Since the cooling water outlet is formed on the side surface of the cylinder head between both cylinders, the temperature of the cooling water in both cylinders can be maintained equally, resulting in stable cooling performance.

To explain in detail, a cooling water outlet common to both cylinders is formed on the side of the cylinder head at the middle part in the longitudinal direction between both cylinders, and a cooling water thermostat is placed at the middle position of both cylinders and connected to the cooling water outlet. This makes it possible to equalize the cooling water temperature in both cylinders, improving cooling performance.

(4) The cooling water outlet does not interfere with the regular arrangement of cylinder head tightening bolts. That is, since the head tightening bolts can be arranged in the most appropriate regular arrangement, the cylinder head can be securely tightened and there is no risk of pressure leakage.

(5) Since the cooling water outlet common to both cylinders is formed in the middle of both cylinders and is integrated with the cylinder head, compared to a structure in which a cooling water outlet is formed for each cylinder, the flow from the cooling water outlet to the radiator is shorter. Piping becomes easier.

[Brief explanation of drawings]

Fig. 1 is a partial left side view of a motorcycle equipped with a water-cooled two-cylinder engine according to the present invention, Fig. 2 is an enlarged view of the cylinder head in the direction of the arrow in Fig.
FIG. 5, 6... cylinder, 8...
...Integrated cylinder head, 19...Cooling water outlet section.

Claims (1)

[Scope of utility model registration request] In a water-cooled two-cylinder engine in which the cylinders are arranged in parallel in the front and rear and are equipped with an integrated cylinder head for both cylinders, there is a cylinder located between the two cylinders in the longitudinal direction, on either the left or right side of the cylinder head. A cooling water outlet common to both cylinders is formed integrally with the cylinder head, the cooling water outlet is made to protrude in a substantially horizontal lateral direction, and the cooling water thermostat is oriented horizontally and located between both cylinders on the cooling water outlet side. Cylinder head structure of a water-cooled two-cylinder engine in which the cylinder head is placed in a staggered position and connected to the cooling water outlet.