JPS6339766B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a four-stroke multi-valve internal combustion engine suitable for use in a motorcycle, and particularly aims to effectively cool a cylinder head.

Multi-valve internal combustion engines are used for high-output engines because intake and exhaust are easy. However, the structure of the cylinder head is complicated, and even if an attempt is made to cool it with air, a sufficient amount of heat dissipation surface cannot be obtained, and the area around the exhaust valve tends to overheat.

Therefore, it is conceivable to liquid-cool the cylinder head, but a structure in which refrigerant simply flows through the cylinder head may not necessarily be able to effectively cool the vicinity of the exhaust valve.

This invention provides liquid cooling by providing a jacket near the combustion chamber of the cylinder head, communicates the jacket with a refrigerant passage through an inflow passage on the exhaust valve side of the cylinder head, and an outflow passage on the intake valve side, and also supplies refrigerant thereto. A supply pump and a refrigerant tank are provided in the cylinder head, and the pump is driven using a valve drive cam mechanism, thereby minimizing the increase in the external size of the engine.

The present invention will be explained below with reference to illustrated embodiments. 1 in the figure indicates the main body of the engine. The main body 1 consists of a crank chamber 2, a cylinder 3 and a cylinder head 4. 5 is an intake pipe connected to the cylinder head 4, and 6 is an exhaust pipe. A refrigerant tank 7 is disposed on the exhaust valve side of one side of the cylinder head 4, and a trochoid-type pump 8 is disposed on the intake valve side. A refrigerant passage 11a,
11b. 8a is a suction passage of the pump 8, and 8b is a discharge passage. In addition,
In this embodiment, the same type of oil as the lubricating oil of the engine is used as the refrigerant.

As shown in FIG. 3, the cylinder head 4 has a combustion chamber 12 formed on its lower surface by a wall member 14. Reference numerals 15 and 16 denote an intake passage and an exhaust passage, respectively, which communicate with the combustion chamber 12, and are opened and closed by an intake valve 17 and an exhaust valve 18. The intake valve 17 and the exhaust valve 18 are two valves that operate simultaneously as shown in FIGS. 4 and 5, and are opened and closed by an intake camshaft 21 and an exhaust camshaft 22 via a tappet 19. 13 is a valve spring. Cam gears 23 having the same number of teeth are fixed to each of the intake camshaft 21 and the exhaust camshaft 22, and are connected to each other via an intermediate gear 24. In this embodiment, a sprocket 25 is integrally provided with the intermediate gear 24 and is driven by a crankshaft via a timing chain 26. The main shaft 8c of the pump 8 is engaged with the shaft end of the exhaust camshaft 22, and rotates integrally with the main shaft 8c of the pump 8. 27
is a pivot shaft that rotatably supports the intermediate gear 24.

A jacket 31 is formed on the upper surface of the wall member 14 by a partition wall 28 and a peripheral wall 29. As shown in FIG. 6, the jacket 31 has a guide wall 34 between the inlet on the exhaust valve side and the outlet on the intake valve side, so that the flow path of the refrigerant from the vicinity of the exhaust valve to the vicinity of the intake valve is established. It is designed to ensure that the wall member is cooled uniformly. 35 is a cylindrical wall surrounding the outer periphery of the spark plug 36. The inlet of the jacket 31 is connected to the vertical hole 3 as shown in FIGS. 3 and 7.
7 to the lower side of the exhaust passage 16, and the inflow passage 3
8 opens to the side of the exhaust passage 16.
The outlet of the jacket 31 likewise extends downwardly by a vertical hole 39 and communicates with the refrigerant tank 7 through an outlet passage 40 . The outer surface of the refrigerant tank 7 is formed by a cover 41 provided on the side of the cylinder head 4, and within the cover 41, the upper part extends to the upper surface of the partition wall 28 in the cylinder head 4. It is formed. 43
4 is a refrigerant inlet formed in the head cover 42;
4 is its screw cap.

The cooling device configured as described above operates as follows when the engine is operated. Exhaust camshaft 22
When the pump 8 is driven to operate, the pump 8 sucks refrigerant from the refrigerant tank 7 through the suction passage 8a, and supplies it to the radiator 9 through the refrigerant passage 11a from the discharge passage 8b. When the vehicle is running, the running wind acts on the radiator 9 and cools the refrigerant. The cooled refrigerant flows into the lower surface of the exhaust passage 16 from the inlet passage 38 through the passage 11b, and cools it while passing through the vertical hole 37.
rises, passes under the tappet 19 and flows into the jacket 31. As shown in FIG. 6, the refrigerant passes through the exhaust valve 18 and the guide wall 3 when the temperature is low
4 and flows upward in the figure while cooling the vicinity of the exhaust valve 18 and the ignition plug 36, where it turns and flows between the intake valve 17 and the guide wall 34.
It flows downward while cooling the vicinity of 7 and reaches the vertical hole 39. During this time, the wall member 14 is evenly and uniformly cooled. The refrigerant heated by cooling the wall member 14 descends in the vertical hole 39 and flows from the outlet passage 40 to the refrigerant tank 7.
Reflux into the inside. Note that if the heat dissipation fins 45 are formed on the outer surface of the peripheral wall 29 forming the jacket 31,
The refrigerant is not only cooled in the radiator 9 but also directly cooled by the traveling wind acting on the heat radiation fins 45 .

As described above, the present invention provides a cylinder head with a pump linked to a valve operating camshaft, and circulates a refrigerant for cooling the cylinder head between the jacket and the radiator. Since the engine liquid-cools only the cylinder head, the radiator is small and easy to install. In addition, a pump is provided on the exhaust valve side of one side of the cylinder head, and a refrigerant tank is provided on the intake valve side, and the jacket and radiator are connected via an inflow path on the exhaust valve side and an outflow path on the intake valve side. Since they are communicated through the refrigerant passage, not only can the cylinder head, pump, and refrigerant tank be brought close to each other, but also the refrigerant can flow from the exhaust valve side to the intake valve side. Therefore, the refrigerant passage can be shortened as much as possible, and the wall member at the top of the combustion chamber, which is the most difficult to cool in a multi-valve internal combustion engine, can be cooled, and in particular, the area around the exhaust valve, which is easily heated, can be effectively cooled. can do.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is an overall view schematically showing the cooling device, Fig. 2 is an enlarged side view of the main parts, Fig. 3 is a cross-sectional view, and Fig. 5 is a sectional view, FIG. 6 is a sectional view, and FIG. 7 is a sectional view. 7... Refrigerant tank, 8... Pump, 9... Radiator, 14... Wall member, 17... Intake valve, 18
...exhaust valve, 21...intake camshaft, 22...exhaust camshaft, 31...jacket.

Claims (1)

[Claims] 1 At least an intake valve 5 and an exhaust valve 6 in one cylinder
In a multi-valve internal combustion engine, the cylinder head 4 is provided with an intake camshaft 21 and an exhaust camshaft 22 for driving the respective valves, and the exhaust camshaft is provided on the exhaust valve side of one side of the cylinder head. 22
A pump 8 linked to the combustion chamber 12 is disposed, and a refrigerant tank 7 is disposed on the intake valve side.A jacket 31 is formed on the outer periphery of the wall member 14 forming the combustion chamber 12, and the jacket 31 and the radiator 9 are connected to the cylinder. A cooling system for a multi-valve internal combustion engine in which the pump 8 and the refrigerant tank 7 are interposed in a refrigerant passage that communicates with the head 4 through an inlet passage 38 provided on the exhaust valve side and an outlet passage 40 provided on the intake valve side. .