JP3747902B2 - Internal combustion engine cooling system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cooling system for an internal combustion engine that cools an internal combustion engine such as an engine mounted on a vehicle with a coolant.
[0002]
[Prior art]
Generally, in a cab-over type vehicle, an engine is mounted under the cab floor at the front of the vehicle body. Conventionally, as a cooling system that cools the engine with a coolant, a reserve tank system is often adopted with an emphasis on component cost, rear body mountability with respect to the vehicle, and the like.
In the reserve tank system, there is no particular restriction on the level position where the reserve tank is arranged, and therefore the reserve tank can be freely installed on the front panel side of the cab, for example, in consideration of the rear body mountability. .
[0003]
However, in this reserve tank system, it takes time to separate the gas (vapor) from the coolant during engine operation, and the pressure at the pump inlet when the water pump that circulates the coolant is high. The decrease in flow rate due to the decrease and the occurrence of cavitation is likely to occur, and for this reason, the surge tank method has been increasingly adopted recently.
[0004]
In the case of this surge tank system, the surge tank needs to be arranged at a level position above the uppermost part of the engine (water jacket). Therefore, if the surge tank is installed inside the front panel of the vehicle in consideration of the mounting characteristics of the rear body, the air vent pipe connecting the upper part of the engine and the surge tank protrudes downward due to the floor shape of the cab floor. It is necessary to bend into a substantially U shape.
[0005]
That is, the front side of the cab floor is a stepping portion that falls in a stepped manner below the space between the engine and the surge tank and is positioned below the upper portion of the engine. In order to avoid mechanical interference with the part, it must be bent into a substantially U-shape that passes under the stepping part.
[0006]
[Problems to be solved by the invention]
When changing the coolant, first the drain cock of the radiator is opened and the coolant is drained out of the engine (water jacket) and radiator, but at this time, the air vent pipe is bent in a U-shape. If it does, a coolant will remain and remain in the U-shaped trough.
[0007]
After draining the coolant, the drain cock is closed and coolant is injected from the surge tank inlet through the makeup line into the engine and radiator. At this time, the coolant is replenished so as to rise from the lower part of the engine to the upper part, and in accordance with this, the air in the engine is discharged to the outside through the air vent pipe. If the coolant remains in the U-shaped valley of the piping, it will be difficult to remove the air from the engine, and it will not be possible to fill the engine with the coolant, resulting in a significant reduction in cooling efficiency. Will be invited.
[0008]
The present invention has been made paying attention to such points, and the object of the present invention is to provide cooling even when the air vent pipe is bent in a substantially U shape due to the floor shape of the cab floor. An internal combustion system that reliably prevents coolant from remaining in the air vent piping when the fluid is withdrawn, and allows the coolant to be filled without leaving air throughout the coolant circulation path when the coolant is injected. It is to provide an engine cooling system.
[0009]
[Means for Solving the Problems]
In the cooling system according to the first aspect of the present invention, the coolant circulates in the circulation path between the internal combustion engine and the radiator. A surge tank is provided at a level above the uppermost part of the circulation path, and the surge tank and the upper part of the circulation path communicate with each other via an air vent pipe. Is located at a level below the top of the circuit . A branch pipe that extends downward and communicates with the drain pipe of the radiator is provided at the lowermost part of the air vent pipe, and the liquid level when the coolant is injected into the circulation path in the middle of the branch pipe. And a valve mechanism that is opened when the coolant in the circulation path is discharged to the outside through the drain pipe.
[0010]
When the coolant is extracted from the circulation path, the valve mechanism is opened, and therefore the coolant in the air vent pipe is discharged to the outside through the valve mechanism. When the cooling liquid is injected, the valve mechanism is closed in accordance with the rising of the cooling liquid, thereby preventing the cooling liquid from flowing into the air vent pipe. As the cooling liquid rises, the air in the circulation path is discharged to the outside through the air vent pipe, so that the entire area in the circulation path is filled with the cooling liquid.
[0011]
In the invention of claim 2, the surge tank of the cooling system of claim 1 is provided with an overflow pipe leading out from the upper part, and a pressure valve that opens and closes according to the pressure in the surge tank is provided in the overflow pipe. Yes.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows the structure of the cooling system 1 mounted on the chassis frame A of the cab-over type vehicle, and FIG. 2 shows the configuration of the coolant circuit of the cooling system 1.
[0013]
A cab B is provided on the chassis frame A so as to cover the cooling system 1, and the cab B can be turned upside down by pushing up the rear part thereof. Is released.
The cooling system 1 includes an engine 3 as an internal combustion engine and a radiator 4 for cooling the engine 3. The engine 3 and the radiator 4 are connected by an outflow pipe 5 and an inflow pipe 6 to form a coolant circulation path 9. .
A cooling fan (not shown) covered with a fan shroud 7 is provided between the engine 3 and the radiator 4. The cooling fan is driven and rotated by the engine 3, and the cooling air is directed toward the radiator 4. It is designed to blow air.
[0014]
A water pump 8 shown in FIG. 2 that rotates in conjunction with the cooling fan is provided in the engine 3, and the coolant is circulated in the circulation path 9 by the rotation of the water pump 8. That is, the coolant in the engine 3 flows into the radiator 4 through the outflow pipe 5 by the rotation of the water pump 8, and the coolant in the radiator 4 sequentially circulates in the engine 3 through the inflow pipe 6. To do.
[0015]
The outflow pipe 5 is provided so as to connect the upper part of the engine 3 and the upper part of the radiator 4, and the inflow pipe 6 is provided so as to connect the lower part of the engine 3 and the lower part of the radiator 4. A drain pipe 10 is connected to the lower end of the radiator 4, and a drain cock 11 for opening and closing the drain pipe 10 is provided on the drain pipe 10.
[0016]
A surge tank 15 is provided on the upper front side of the radiator 4. The surge tank 15 is provided at a level above the upper part of the engine 3 that is the uppermost part of the circulation path 9 and at a position adjacent to the inside of the front panel B1 of the cab B.
[0017]
A make-up pipe 16 is led out from the lower end of the surge tank 15, and the lead-out side end of the make-up pipe 16 is connected in the middle of the inflow pipe 6 so as to communicate with the engine 3 and the radiator 4.
[0018]
An air vent pipe 19 is led out from the upper part of the engine 3, which is the uppermost part of the circulation path 9, and an outlet side end portion of the air vent pipe 19 is connected to the upper part of the side surface of the surge tank 15.
The cab floor B2 in the cab B is formed in a space between the engine 3 and the surge tank 15 by extending from the seat installation part B2a on the engine 3 to the front side of the seat installation part B2a. It consists of foot part B2b arrange | positioned so that it may fall.
[0019]
The air vent pipe 19 is bent in a substantially U shape that protrudes downward along the lower side of the step B2b in order to avoid mechanical interference with the step B2b in the cab floor B2. .
[0020]
A branch pipe 20 is led out from the lowermost part of the air vent pipe 19, and a lead-out side end of the branch pipe 20 extends to the lower side of the air vent pipe 19 and is connected to the drain pipe 10.
[0021]
In the middle of the branch pipe 20, a valve mechanism 21 is provided near the air vent pipe 19. As shown in FIG. 3, the valve mechanism 21 includes a valve seat 22 provided in a cross section of the branch pipe 20, and a ball-like shape provided freely in the branch pipe 20 below the valve seat 22. The valve body 23 is provided with a central portion of the valve seat 22 serving as a flow hole 22a. The valve body 23 contacts and separates from the opening surface of the flow hole 22a, thereby opening and closing the passage in the branch pipe 20. It is like that. The valve body 23 is made of a material having a specific gravity smaller than that of the coolant, for example, a resin material. A pin 24 that restricts the movement range of the valve body 23 is provided below the valve seat 22.
[0022]
An inlet 28 is formed on the upper side of the surge tank 15 on the side facing the front panel B1 of the cab B, and a cap 29 is detachably fitted into the inlet 28. It is sealed.
[0023]
An overflow pipe 30 is led out from the upper part of the surge tank 15, and the overflow pipe 30 extends downward from the upper part of the surge tank 15. A pressure valve 31 is attached in the middle of the overflow pipe 30. The pressure valve 31 includes a pressurization valve and a negative pressure valve. When the pressure in the surge tank 15 is the same as the set pressure of the pressure valve 31, both the pressurization valve and the negative pressure valve are closed, and the pressure in the surge tank 15 is higher than the set pressure. When the pressure becomes, the pressurization valve opens, and when the pressure becomes lower than atmospheric pressure (negative pressure), the negative pressure valve opens.
[0024]
The cooling system 1 is filled with cooling liquid so that the liquid level in the surge tank 15 is maintained at a level F higher than that of the upper part of the engine 3.
[0025]
When the engine 3 is started in this state, the water pump 8 is rotated, and the coolant is circulated between the engine 3 and the radiator 4 by the rotation of the water pump 8, and the engine 3 is cooled by the coolant.
[0026]
The heat of the coolant that has become high due to heat exchange with the engine 3 is dissipated while the coolant flows through the radiator 4, and this heat dissipation suppresses the temperature rise of the coolant above a predetermined level. The thermal expansion of the coolant flows into the surge tank 15 from the engine 3 through the air vent pipe 19. The remaining air in the cooling system 1 mixed in the coolant is separated from the coolant and collected in the surge tank 15 when the coolant flows into the surge tank 15.
[0027]
When the inside of the surge tank 15 rises above the set pressure of the pressure valve 31 due to the expansion of the cooling liquid or gas-liquid separated gas, the pressure valve 31 opens at that pressure, and the gas or cooling liquid in the surge tank 15 opens. The expanded portion is discharged to the outside through the overflow pipe 30.
[0028]
When the coolant in the surge tank 15 flows out through the make-up pipe 16, the liquid level of the coolant in the surge tank 15 decreases. When the pressure in the surge tank 15 becomes negative due to the decrease in the liquid level, the negative pressure is reduced. The negative pressure valve of the pressure valve 31 is opened by the pressure, and air in the atmosphere flows into the surge tank 15 through the overflow pipe 30, whereby the surge tank 15 is maintained at the same pressure as the atmospheric pressure.
[0029]
On the other hand, when the coolant in the cooling system 1 is replaced, first, the cap 29 is removed from the inlet 28 of the surge tank 15 to open the inlet 28, and the drain cock 11 is operated to open the drain pipe 10. To do.
[0030]
When the drain pipe 10 is opened, the coolant in the radiator 4 is discharged to the outside through the drain pipe 10, and the coolant in the engine 3 is discharged to the outside through the inflow pipe 6, the radiator 4 and the drain pipe 10, The coolant in the surge tank 15 is discharged to the outside through the makeup pipe 16, the inflow pipe 6, the radiator 4, and the drain pipe 10.
Further, the coolant in the branch pipe 20 is discharged to the outside through the drain pipe 10. At the time of this discharge, the liquid level of the cooling liquid in the branch pipe 20 is lowered, and the valve body 23 of the valve mechanism 21 is lowered as shown in FIG. The flow hole 22a is opened.
[0031]
The coolant in the air vent pipe 19 flows into the branch pipe 20 through the flow hole 22a when the flow hole 22a is opened, and is discharged to the outside through the drain pipe 10 from the branch pipe 20.
[0032]
In this way, all the coolant in the cooling system 1 is discharged to the outside. In other words, the air vent pipe 19 is bent in a substantially U shape due to the arrangement of the stepping portion B2b of the cab floor B2, but the internal coolant is opened by opening the valve mechanism 21 regardless of the shape of the branch pipe 20. It can be discharged to the outside accurately through.
[0033]
After all the cooling liquid in the cooling system 1 is discharged to the outside, the drain pipe 10 is closed and new cooling liquid is sequentially injected from the inlet 28 of the surge tank 15. The coolant injected into the surge tank 15 flows into the radiator 4 through the make-up pipe 16, and the liquid level rises. At the same time, the coolant flows into the engine 3 through the inflow pipe 6, and the liquid level is increased. Further, the coolant flows into the branch pipe 20 and the liquid level rises.
[0034]
When the liquid level in the branch pipe 20 rises, the valve body 23 moves upward together with the liquid level. During the upward movement, the valve body 23 contacts the valve seat 22 and the flow hole 22a is closed. Is retained. Therefore, the inflow of the coolant from the branch pipe 20 to the air vent pipe 19 is prevented.
[0035]
When the liquid level in the engine 3 and the radiator 4 rises, the air in the engine 3 and the radiator 4 is sequentially discharged into the surge tank 15 through the air vent pipe 19 and further discharged from the surge tank 15 through the inlet 28 to the outside. The Finally, the coolant flows into the air vent pipe 19 from the upper part of the engine 3, and the air is not left in the engine 3 and the radiator 4, and the cooling system 1 is cooled while maintaining a higher level F than the upper part of the engine 3. The liquid is filled.
[0036]
After the injection of the coolant is completed, the surge tank 15 is sealed by fitting the cap 29 into the injection port 28. This completes the coolant replacement operation.
[0037]
Thus, in the cooling system 1 according to this embodiment, the surge tank 15 is disposed on the front side of the engine 3, and the air vent pipe 19 that connects the engine 3 and the surge tank 15 is connected to the stepping portion B2b of the cab floor B2. Although it is in a state of being bent in a substantially U shape so as not to interfere, when the cooling liquid is extracted from the cooling system 1 during the replacement of the cooling liquid, the cooling in the air vent pipe 19 having a substantially U shape is performed. The liquid can also be reliably discharged outside.
[0038]
Therefore, at the time of injecting the coolant, the air in the engine 3 and the radiator 4 can be reliably discharged to the outside through the air vent pipe 19, thereby leaving the air in the circulation path 9 without leaving the air in the engine 3 and the radiator 4. It is possible to reliably fill the coolant and prevent a decrease in cooling efficiency.
[0039]
Thus, the surge tank 15 can be provided on the front side of the engine 3, that is, adjacent to the inside of the front panel B1 of the cab B, thereby improving the mountability of the rear body.
[0040]
In addition, since the cooling system 1 has a surge tank type configuration that is superior in the gas-liquid separation of the cooling liquid as compared with the reserve tank type, good cooling performance can be obtained. By the way, in the conventional general surge tank, a cap having a pressure valve is provided at the inlet, so that the cap is thick and large, so the surge tank is adjacent to the inside of the front panel of the cab. In order to avoid mechanical interference between the cap and the front panel, the surge tank must be made smaller in size, resulting in a shortage of capacity.
[0041]
However, in this embodiment, the surge tank 15 is provided with the overflow pipe 30 and the overflow pipe 30 is provided with the pressure valve 31. Therefore, the injection port 28 is simply provided with a thin and small simple cap 29. As a result, the surge tank 15 can be disposed adjacent to the inner side of the front panel B1 without being particularly small, and therefore the capacity can be sufficiently secured.
[0042]
FIG. 4 shows a modification of the valve mechanism 21 provided in the branch pipe 20. In this valve mechanism 21, a valve seat 35 is formed by denting a peripheral wall in the middle of the branch pipe 20 in a C-shaped cross section inside. A ball-shaped valve body 36 is formed below the valve seat 35.
[0043]
In the case of this valve mechanism 21, the valve body 36 comes into contact with the valve seat 35 as the coolant in the branch pipe 20 rises, whereby the flow hole 35 a inside the valve seat 35 is closed, and the branch pipe 20. The valve body 36 is separated from the valve seat 35 in accordance with the lowering of the coolant inside, and the flow hole 35a is opened.
[0044]
FIG. 5 shows still another modification of the valve mechanism 21. In this modification, the branch pipe 20 is inserted in a liquid-tight manner into the first pipe body 20a and the first pipe body 20a. And a valve seat 38 is formed by tapering the end of the second tube 20b into a tapered shape. A ball-shaped valve is formed below the valve seat 38. A body 39 is provided.
[0045]
In the case of this valve mechanism 21, the valve body 39 comes into contact with the valve seat 38 as the coolant in the branch pipe 20 rises, the flow hole 38 a inside the valve seat 38 is closed, and the branch pipe 20. The valve body 39 is separated from the valve seat 38 in accordance with the lowering of the coolant inside, and the flow hole 38a is opened.
[0046]
In the above-described embodiment, the branch pipe 20 is directly connected to the drain pipe 10 of the radiator 4. However, the branch pipe 20 is not necessarily connected to the drain pipe 10. For example, the lower part of the radiator 4 or the lower part of the inflow pipe 6 is used. In short, the branch pipe 20 may be provided so as to extend downward from the lowermost part of the air vent pipe 19 and communicate with the drain pipe 10 of the radiator 4.
[0047]
【The invention's effect】
As described above, according to the first aspect of the present invention, even when the air vent pipe is bent in a substantially U shape, the remaining of the coolant in the air vent pipe is surely prevented when the coolant is withdrawn. Thus, the cooling liquid can be accurately filled without leaving air over the entire area of the cooling liquid circulation path when the cooling liquid is injected.
[0048]
In addition to this, according to the invention of claim 2, the surge tank can be arranged, for example, adjacent to the inside of the front panel of the cab without having a small size, and sufficient capacity can be secured. it can.
[Brief description of the drawings]
FIG. 1 is a side view showing a structure of a cooling system according to an embodiment of the present invention.
FIG. 2 is a configuration diagram schematically showing a coolant circuit of the cooling system.
3A and 3B show a valve mechanism used in the cooling system, wherein FIG. 3A is a longitudinal sectional view when the valve is closed, FIG. 3B is a sectional view when the valve is opened, and FIG. Sectional drawing which follows a C line.
FIG. 4 is a cross-sectional view showing a modification of the valve mechanism.
FIG. 5 is a cross-sectional view showing still another modified example of the valve mechanism.
[Explanation of symbols]
A ... Chassis frame B ... Cab B1 ... Front panel B2 ... Cab floor B2b ... Foot part 3 ... Engine 4 ... Radiator 5 ... Inlet pipe 6 ... Outlet pipe 10 ... Drain pipe 15 ... Surge tank 16 ... Makeup pipe 19 ... Air vent Pipe 20 ... Branch pipe 21 ... Valve mechanism 28 ... Inlet 29 ... Cap 30 ... Overflow pipe 31 ... Pressure valve

Claims (2)

Coolant circulates in the circulation path between the internal combustion engine and the radiator, and the space between the uppermost part of the circulation path and a surge tank provided at a level higher than the uppermost part is provided through an air vent pipe. In the internal combustion engine cooling system, which is in communication with each other, and the middle part of the air vent pipe is arranged at a level below the uppermost part of the circulation path ,
A branch pipe extending downward from the lowermost part of the air vent pipe and leading to the drain pipe of the radiator is provided, and the liquid level rises when coolant is injected into the circulation path in the middle of the branch pipe The internal combustion engine cooling system is provided with a valve mechanism that is closed when the coolant in the circulation path is discharged to the outside through the drain pipe. 2. The internal combustion engine according to claim 1, wherein the surge tank includes an overflow pipe that is led out from an upper portion thereof, and a pressure valve that opens and closes according to a pressure in the surge tank is provided in the overflow pipe. Cooling system.

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