JPH0451652B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cooling system for a water-cooled internal combustion engine.

[Conventional technology]

FIG. 3 shows an example of a conventional cooling system for a water-cooled internal combustion engine. In the figure, a crankcase 11 supports a cylinder liner 12, and a cylinder head 13 is mounted on the upper part of the cylinder liner 12.
A piston 14 is provided on the inner surface of the cylinder liner 12.
is sliding. A combustion chamber 15 is formed by the cylinder head 13, cylinder liner 12, and piston 14. The cooling water discharged from the cooling water pump 21 driven by the crankshaft 35 enters the lower part of the cooling water jacket 22 composed of the crankcase 11 and the cylinder liner 12, cools the outer surface of the cylinder liner 12, and flows to the upper part. A communication hole 23
The cooling water flows into the cooling water reservoir 24 of the cylinder head 13 from there. On the other hand, air is supplied to the combustion chamber 15 from an air supply pipe 32 through an air supply passage 33 in the cylinder head 13. Further, exhaust gas from the combustion chamber 15 is discharged from an exhaust passage in the cylinder head 13 (not shown) via an exhaust pipe 34.

Here, the cooling water in the cooling water reservoir 24 of the cylinder head 13 flows around the air supply passage 33 as shown, and then reaches the thermostat 27 through the cooling water outlet pipe 25. Most of the cooling water from the thermostat 27 passes through the space 28 and the pipe 29, and some of it passes through the bypass pipe 31 to the cooling water pump 21.
leading to the suction port.

Next, the operation of the conventional example will be explained.

The cooling water discharged from the cooling water pump 21 first cools the cylinder liner 12 in the cooling water jacket 22, its temperature rises, and then flows into the cooling water reservoir 24 of the cylinder head 13. Here, the water temperature is normally set at about 80°C in the thermostat 27, and the temperature of the cooling water from the cooling water outlet pipe 25 is maintained at approximately 80°C. Therefore, the air supply passage 33 in the cooling water reservoir 24 is surrounded by cooling water at approximately 80°C. However, the supply air flowing into the air supply passage 33 from the air supply pipe 32 is normally at atmospheric temperature, which is about 20°C. Therefore, the supply air flowing through the air supply passage 33 is heated by the cooling water in the cooling water reservoir 24, and its temperature increases. Therefore, the air supply supplied to the combustion chamber 15 is heated in the air supply passage 33, and its temperature increases.

This has the same effect as increasing atmospheric temperature, resulting in a decrease in output and worsening of fuel efficiency.

Incidentally, according to the output modification formula of JIS D1005-1976, the output modification coefficient is expressed by the following formula.

P _a : Measured atmospheric pressure mmHg P _w : Partial pressure of water vapor in the atmosphere mmHg θ : Intake atmospheric temperature °C Here, the supply air at the standard suction state of 20°C rises in temperature by about 20°C in the ventilation passage 33 to 40°C, 3.3 % reduction in output and deterioration of fuel efficiency, which has a large impact on engine performance.

[Problem to be solved by the invention]

As mentioned above, in conventional cooling systems, the cooling water that flows into the cylinder head has cooled the cylinder liner, and the temperature has increased, so the supply air is heated by this, which reduces the suction efficiency. At the same time, the cylinder liner was cooled more than necessary, resulting in a decrease in output and poor fuel efficiency.

An object of the present invention is to provide a cooling system for an internal combustion engine that eliminates the drawbacks of the conventional devices, improves intake efficiency, prevents overcooling of the cylinder liner, and improves output and reduces fuel consumption. It is in.

[Means to solve the problem]

The cooling system for an internal combustion engine according to the present invention aims to lower the temperature of the inflow into the cylinder head by first letting the entire amount of cooling water flow into the cylinder head, and also directs the entire amount of cooling water flowing out from the cylinder head to the exhaust gas, oil, etc. After being heated by a heating means such as a cooler, the cylinder liner is made to flow into the lower part of the cooling water jacket on the outer periphery of the cylinder liner to cool the cylinder liner, and is configured to flow out from the upper part of the cooling water jacket and lead to the thermostat, thereby achieving the above object. It is characterized by the following.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 shows a first embodiment of the invention. The entire amount of cooling water discharged from the cooling water pump 21 is transferred to the pipe 51.
first through the cooling water reservoir 24 of the cylinder head 13.
to flow into. Further, a cooling water passage 43 is provided around the exhaust pipe 42 to exchange heat between the cooling water and the exhaust gas.
Here, the entire amount of cooling water that has flowed out of the cylinder head 13 and passed through the cooling water outlet pipe 41 flows into the cooling water passage 43 of the exhaust pipe 42 to exchange heat with the exhaust gas, and then is passed through the piping 44 to the crankcase 11 and the cylinder. The cooling water is introduced into the lower part of the cooling water jacket 22 formed by the outer peripheral surface of the liner 12. Thereafter, the cooling water flows out from the upper part of the cooling water jacket 22 and reaches the thermostat 27 through the pipe 45.

The thermostat 27, like the conventional one, has a
High-temperature cooling water of 80°C or higher is cooled by flowing into the radiator 28, and low-temperature cooling water below that is passed through the bypass pipe 3.
1 to the inlet and outlet of the cooling water pump 21.

The piping 51, the piping 41, and the piping 44 constitute an inlet side cooling channel 60, and the piping 45 constitutes an outlet side cooling channel 70.

Next, the operation of the above embodiment will be explained. The thermostat 27 is set at about 80°C like the conventional one, but the cooling water discharged from the cooling water pump 21 is directly sent to the cooling water reservoir 24 of the cylinder head 13.
Therefore, the inflow temperature of the cooling water is lower than in the conventional case, and the degree to which the supply air is heated is reduced by that amount, and the efficiency of intake air into the combustion chamber 15 is increased.

Next, the relatively high-temperature cooling water that cools the cylinder head 13 and flows out from the cooling water reservoir 24 is further heated by exhaust gas in the cooling water passage 43 of the exhaust pipe 42, and then flows into the cooling water jacket 22 of the crankcase 11. Flows into the bottom. After cooling the cylinder liner 12, the cooling water flows out from the upper part of the cooling water jacket 22 and is guided to the thermostat 27 through the pipe 45.

As a result, the temperature of the cooling water flowing through the cooling water jacket 22 on the outer periphery of the cylinder liner becomes higher than that of the conventional cooling water jacket, thereby preventing overcooling of the cylinder and improving fuel efficiency.

FIG. 2 shows a second embodiment of the present invention, in which the cooling water flowing out from the cooling water reservoir 24 of the cylinder head 13 flows into the oil cooler 51 to cool the oil and heat itself. The cooling water flows into the lower part of the cooling water jacket 22. Therefore, the first
In the embodiment, the cooling water flows through the cooling passage 4 of the exhaust pipe 42.
3, the same effect as heating by exhaust gas can be obtained.

〔Effect of the invention〕

As described above, the cooling system for an internal combustion engine according to the present invention reduces the temperature of the water flowing into the cylinder head by first allowing the entire amount of cooling water cooled by the cooler from the water pump to flow into the cylinder head. Therefore, it is possible to prevent deterioration of intake efficiency due to a rise in intake air temperature and increase output. In addition, the cooling water flowing out from the cylinder head is heated by the exhaust gas or oil cooler and then flows into the water jacket of the cylinder block, which prevents a decrease in mechanical efficiency due to overcooling of the cylinder and improves fuel efficiency and engine performance. In addition to being able to measure the temperature, it is also possible to prevent sulfuric acid corrosion from occurring.

Furthermore, since a means for heating the cooling water is provided at the cylinder head outlet, the temperature of the cooling water entering the cooling water jacket can be maintained at a high temperature, and the cooling water temperature can be maintained at a high temperature, especially when the engine is operating in a cold region and the load on the engine is low. This makes it possible to quickly raise the fuel consumption rate, and from this aspect as well, it is possible to reduce the fuel consumption of the engine and prevent sulfuric acid corrosion of the cylinder liner.

[Brief explanation of the drawing]

1 and 2 are system diagrams showing a cooling system for an internal combustion engine according to the present invention. FIG. 1 is a diagram of a first embodiment, and FIG. 2 is a diagram of a second embodiment. FIG. 3 is a diagram of a conventional cooling system. 11...Crank case, 12...Cylinder liner, 13...Cylinder head, 21...Cooling water pump, 22...Crankcase cooling water jacket, 24...Cooling water reservoir, 27...Thermostat, 28... Radiator, 42...Exhaust pipe, 43
...Cooling water passage, 51...Oil cooler, 60...
...Inlet side cooling waterway, 70...Outlet side cooling waterway.

Claims (1)

[Claims] 1. In a water-cooled internal combustion engine that is equipped with a thermostat that diverts the cooling water at the engine outlet to a radiator or bus pass pipe depending on its temperature and cools the cylinder head and cylinder liner with water, the cooling water discharged from the cooling water pump An inlet cooling water channel is provided which is configured to allow the entire amount of cooling water to first flow into the cylinder head, and to cause the entire amount of cooling water from the cylinder head outlet to flow into the lower part of the cooling water jacket of the crankcase. A heating means for heating cooling water is provided between the cylinder head outlet and the cooling water jacket inlet of the crankcase, and an outlet configured to guide the cooling water flowing out from the upper part of the cooling water jacket to the thermostat. A cooling system for an internal combustion engine characterized by having a side cooling channel.