JPH0236899Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a device for preventing cavitation erosion occurring around the cylinder of a water-cooled engine.

Engines with wet liner type cylinders tend to cause cavitation in the cooling water surrounding the cylinders due to vibrations of the cylinder liner and cylinder block during operation.

This cavitation is water vapor bubbles generated in the cooling water that comes into contact with the outer periphery of the cylinder liner, and is caused by a drop in water pressure due to engine vibration. These bubbles are generated in the low-pressure area using minute depressions on the liner surface as nuclei, and instantly collapse when the next high pressure is reached. At this time, high-frequency water pressure fluctuations are generated inside the cooling channel, causing the liner surface to rise. Cavitation erosion occurs in the recess.

Figure 1 shows a conventional engine cooling system. When the cooling water temperature is low, such as during startup, the thermostat 5 closes and the cooling water is routed through the bypass cooling water passage instead of being routed from the engine body 3 to the radiator 4. The water is again supplied from the water pump 2 to the area around the cylinder liner of the engine body 3 via the water pump 6 to promote warm-up.

On the other hand, after warm-up, the cooling water temperature becomes high and the thermostat 5 opens, so the warm cooling water from the engine body 3 is once cooled by the radiator 4 and then circulates through the engine body 3 again. During engine operation, cooling water constantly flows from the thermostat 5 and the radiator 4 through the air pipes 9 and 11 into the water tank 1 to separate air and water.

However, as mentioned above, when the engine vibration is significant, the pressure of the cooling water that comes into contact with the cylinder liner surface fluctuates, causing cavitation formed by saturated steam to repeatedly form and collapse, thereby causing cylinder liner erosion. This eventually led to the problem of reduced durability of the engine itself.

This invention was developed with a focus on these problems, and aims to solve the above problems by mixing the air in the air chamber of the water tank as bubbles into the cooling water circulating in the cooling system. shall be.

To this end, in the present invention, in a water-cooled engine equipped with a wet cylinder liner, a cooling water passage from the engine body to the suction side of the water pump via the radiator, a bypass cooling water passage that bypasses the radiator, A thermostat that opens the bypass cooling water passage when the cooling water temperature is below a predetermined value, and a water tank storing a predetermined amount of cooling water to be supplied to the cooling water passage, and an air chamber of the water tank and a bypass cooling An air passage is provided that communicates with the water passage, and this allows air to flow into the cooling water in the bypass cooling water passage based on the differential pressure between the suction side pressure of the water pump and the air chamber only when the cooling water temperature is below a predetermined value. Air from the chamber was introduced to mix air bubbles into the cooling water.

Embodiments of the present invention will be described below based on the drawings, in which the same components as in FIG. 1 are given the same reference numerals.

In Figures 2 and 3, 1 is a water tank, 2 is a water pump, 3 is an engine body, and 4 is a water tank.
is a radiator and has the same configuration as a conventional cooling system.

That is, the coolant heated by the engine body 3 is supplied to the thermostat 5, and when the coolant temperature is below a predetermined value, it is directly supplied from the thermostat 5 to the water pump 2 via the coolant passage 6, and then It is then pressure-fed to the engine body 3 and circulated through these cooling systems.

On the other hand, when the cooling water temperature exceeds a predetermined value, the thermostat 5 opens and the cooling water is sufficiently cooled by the radiator 4, and then a portion of the cooling water is sent directly to the water pump 2, and the remaining portion is temporarily returned to the water tank 1. The water is supplied to the water pump 2. In this way, the cooling water is kept cool and circulated through the cooling system so that the temperature of the cooling water does not exceed a certain value in the radiator 4.

In this embodiment, a bypass cooling water passage 6 is connected to the air chamber 1A of the water tank 1 and the thermostat 5 to the suction side of the water pump 2.
An air passage 7 is formed which communicates with the air passage 7
The connecting portion 7A with the cooling water passage 6 is configured such that air is mixed into the cooling water of the cooling water passage 6 as bubbles.
It is formed in a nozzle shape, and air is supplied into the cooling water by the pressure difference between the pressure in the air chamber 1A of the water tank 1 and the upstream suction pressure of the water pump 2.

The air bubbles are pumped together with cooling water to the engine body 3 by the water pump 2, and are directed to the thermostat 5 after passing through a cooling water passage around a cylinder liner (not shown).

And the cooling water channel 8 just before the thermostat 5
The cooling water and air are then branched from the cooling water channel 8 and flow through an air pipe 9 communicating with the air chamber 1A of the water tank 1. An air pipe 11 is also connected from the radiator 4 to the water tank 1 to perform steam and water decomposition. Thereafter, the air is mixed into the cooling water from the air passage 7 again and circulated around the cylinder liner of the engine body 3.

In this embodiment, the total amount of water and air in the cooling system is constant, and air is released from the pressure valve 10 only when the air pressure in the cooling system becomes abnormally high.

When the engine is at a low temperature, the thermostat 5 closes to cool the engine body 3, and the cooling water flows into the suction side of the water pump 2 from the bypass cooling water passage 6, but does not flow into the radiator 4.

When the engine is running, vibrations of the cylinder liner and cylinder block cause water pressure fluctuations in the cooling water passage around the cylinder liner, and cavitation becomes more severe at low temperatures.

However, as mentioned above, air is mixed in from the air passage 7 in the middle of the bypass cooling water passage 6, and the circulating cooling water contains air bubbles. changes elastically.

Therefore, pressure fluctuations within the cooling water passage can be reduced, and cavitation, which tends to occur when pressure fluctuations occur, can be effectively suppressed.

On the other hand, at high temperatures when cavitation is less likely to occur, the cooling water is circulated through the engine body 3 via the radiator 4 according to the control of the thermostat 5.
It does not flow through the bypass cooling water passage 6.

Therefore, in this case, the air from the air passage 7 is not mixed into the cooling water, and the cooling system only enhances the cooling function of the engine body 3 through its high cooling action, thereby improving engine cooling efficiency. .

As explained above, according to the present invention, in the cooling system of an engine having a wet type cylinder liner,
By mixing the air in the air chamber of the water tank, cavitation that tends to occur in the cooling water passage around the cylinder liner due to engine vibration is prevented, and as a result, cylinder liner erosion is suppressed and engine durability is increased. It has the effect of being able to

In addition, in this invention, air is supplied to the bypass cooling water passage via the thermostat.
Since air bubbles are mixed into the cooling water only when the cooling water temperature is below a predetermined value, there is no risk of a drop in cooling efficiency due to the mixing of air or overheating caused by this at high temperatures. In addition, since air bubbles are mixed into the cooling water using the differential pressure between the suction side pressure of the water pump and the air chamber, there is no need to install a new pressurizing compressor or the like to mix air. It also has the advantage of being simple and low-cost.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing a conventional example, FIG. 2 is a schematic block diagram showing an embodiment of the present invention, and FIG. 3 is a detailed explanatory diagram showing the main parts of the embodiment of the present invention. 1...Water tank, 1A...Air chamber, 2...
...Water pump, 3...Engine body, 4...
Radiator, 5... thermostat, 6... cooling water passage, 7... air passage.

Claims (1)

[Scope of utility model registration request] In a water-cooled engine equipped with a wet type cylinder liner, there is a cooling water passage from the engine body to the suction side of the water pump via the radiator, a bypass cooling water passage that bypasses the radiator, and a cooling water passage whose cooling water temperature is below a predetermined value. A thermostat that sometimes opens the bypass cooling water passage, and a water tank storing a predetermined amount of cooling water to be supplied to the cooling water passage, and an air chamber that communicates the air chamber of the water tank with the bypass cooling water passage. A passage is provided, and when the cooling water temperature is below a specified value,
Cavitation yellow is characterized by introducing air from the air chamber into the cooling water in the bypass cooling water passage to mix air bubbles into the cooling water based on the differential pressure between the suction side pressure of the water pump and the air chamber. Anti-jeong device.