JPH07101006B2 - Water-cooled engine cooling system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a cooling device for a water-cooled engine.

(Prior Art) Knocking due to spontaneous combustion of end gas in a combustion chamber of an engine is likely to occur particularly in a low speed / high load region of the entire operating range of the engine, and in order to suppress this knocking, a cylinder head can be efficiently used. It is known that it is effective to cool to increase the mechanical octane number of the engine (that is, the octane number evaluated from the mechanical aspect).

However, in the conventional general water-cooled engine, since the cylinder head and the cylinder block are cooled by a single cooling system, for example, the operating state of the engine has the highest heat load, and therefore the engine side to the cooling water side. When moving from the high-speed / high-load range, which has the largest amount of heat radiation to the low-speed / high-load range, where knocking occurs most easily,
Since the cooling water has already reached a very high temperature due to operation in the high load range, no matter how much heat is dissipated in the radiator, the cooling water temperature will not immediately drop, so that the low speed / high load range However, there is a problem in that the cooling capacity for the cylinder head becomes low, and as a result, the occurrence of knocking cannot be sufficiently suppressed.

From such a background, the engine cooling system is configured with two mutually independent systems, a head side cooling system for intensively cooling the cylinder head and a block side cooling system for intensively cooling the cylinder block. As a technique for effectively cooling the head to increase the mechanical octane number of the engine, for example, a technique disclosed in Japanese Patent Application Laid-Open No. 57-146010 (hereinafter, referred to as a first known example for convenience) is disclosed. The one disclosed in JP-A-59-224414 (hereinafter referred to as the second known example) has been proposed.

However, in the first known example, since one radiator is shared by the block side cooling system and the head side cooling system, the cooling water that has been heated to a high temperature by the operation in the high speed / high load region can be operated at a low speed.・ In order to quickly reduce the water temperature during operation in the high load range, it is necessary to further increase the radiator capacity designed based on the heat radiation amount in the high speed / high load range where the heat load is usually the highest. It is difficult to apply to an automobile engine whose storage space is limited.

In the second known example, the head side cooling system and the block side cooling system are respectively provided with dedicated radiators. Therefore, the cylinder head side is not affected by the heat load on the cylinder block side. Although there is an advantage of being able to cool effectively, the structure of the cooling system is the same as that of the conventional general cooling device (described above) in which the cooling system of the engine is composed of a single system, considering only the cylinder head. There is a limit to the improvement of the mechanical octane number of the engine by improving the cooling performance for the cylinder head in the low speed / high load region in relation to the heat radiation capacity (size) of the radiator.

On the other hand, considering the cylinder block side, in the low speed / high load range, the heat load is not as high as in the high speed / high load range, so that the cooling capacity is not required as in the high speed / high load range, but this second known example In this case, since the block side cooling system uniformly cools the cylinder block throughout the entire operating range of the engine, in the low speed / high load range, the cylinder block is conversely overcooled and the lubricating oil A decrease in oil temperature may increase the viscosity of the oil, resulting in an increase in sliding resistance of a sliding portion such as a piston.

(Object of the Invention) The present invention is intended to solve the problems pointed out in the above-mentioned prior art, in a water-cooled engine, to improve the mechanical octane number in an operating region where knocking is likely to occur, and to improve the cylinder head. The purpose of the invention is to suppress the increase of the sliding resistance of the engine due to the supercooling and to improve the fuel efficiency and the output performance of the engine.

(Means for Achieving the Purpose) As a means for achieving the above object, the present invention is a water-cooled type including a head side cooling system for cooling a cylinder head of an engine and a block side cooling system for cooling a cylinder block. In the engine, a first radiator and a second radiator are provided, and only the first radiator is provided in a high speed / high load region of the engine, and the first radiator and the second radiator are provided in a low speed / high load region of the engine. Is connected in series, and the cooling water after passing through both the first radiator and the second radiator is made to flow sequentially from the cylinder head side cooling system to the block side cooling system. It was done.

(Operation) According to the present invention, by the above means, (1) two radiators are connected in series in a low speed / high load region where knocking is most likely to occur, and cooling is performed by radiative cooling in two stages by these two radiators. Since water is first supplied to the head side cooling system, the cooling performance for the cylinder head is improved compared to the case where the cooling water is radiated from only one radiator and this is supplied to the head side cooling system. The mechanical octane number is increased and knocking is effectively prevented. (2) In the low speed / high load range, the cooling water with a relatively high water temperature after cooling the cylinder block in the head side cooling system is the block side. The cylinder block is supplied to the cooling system, which cools the cylinder block, thereby effectively preventing overcooling of the cylinder block. , So that the increase in the sliding resistance at the sliding portion of the engine attributable to subcooling of the cylinder block is effectively suppressed, effects etc. are obtained.

(Embodiment) A preferred embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

(First Embodiment) FIG. 1 shows a cooling system for an automobile engine according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 is an engine including a cylinder head 2 and a cylinder block 3. Is.

A water pump 6 is provided at the cooling water inlet 15 of the cylinder head 2.
Is installed. The suction port of the water pump 6 has a first cooling water supply passage 21 communicating with the outflow side of the first radiator 4 and a first cooling water supply passage 21 which is branched from the middle of the first cooling water supply passage 21 to an intermediate portion thereof. The downstream ends of the second cooling water supply passages 22 each including the second radiator 5 are connected to each other. A first valve 9 is attached to a branch portion between the first cooling water supply passage 21 and the second cooling water supply passage 22. The first valve 9 is a solenoid valve switching valve that is controlled to open and close by a control circuit 14 based on the engine load detected from the boost pressure of the engine or the intake air amount and the engine speed detected by a speed sensor or the like. Specifically, in the low speed / high load region of the engine shown by the region a in FIG. 3, specifically, the first radiator 4 and the second radiator 4 are provided.
Of the first radiator 4 by cutting off the connection with the radiator 5 of
Only the first radiator 4 and the second radiator 5 are connected in series in the region c so that only the first radiator 4 and the second radiator 5 are connected to the water pump 6 side (first operating position). Are communicated with the water pump 6 side via the second cooling water supply passages 22 (second operating position). In the region b, the second position is set only when the engine load and the engine speed are constant. That is, when it is assumed that the operating state of the engine will soon shift from the region c to the region a, specifically, in this embodiment, the rate of change in the engine load decreasing direction is equal to or higher than a predetermined level, and It is set to the second operating position when the rate of change in the decreasing direction of the rotational speed is equal to or higher than a predetermined level (when the cooling system control condition is satisfied), and at other times (when the cooling system control condition is not satisfied). It is adapted to be set to the first operating position (that is, the first valve 9 in this region b).
That is, predictive control will be performed).

On the other hand, the cooling water outlet 16 of the cylinder head 2 is connected to the suction side of the first radiator 4 via the first cooling water return passage 23. Further, a thermostat 13 is provided in the first cooling water return path 23. This thermostat
When the temperature of the cooling water is 60 ° C. or lower, the cooling water from the cylinder head 2 side is returned to the first radiator 4 side via the first cooling water return path 23 when the cooling water temperature is 60 ° C. or higher. This acts so as to circulate it to the water pump 6 side via the bypass passage 24. In addition, the first cooling water return path 23 is located at a position downstream of the thermostat 13 in the first cooling water return path 23.
Is connected to the cooling water inlet 17 of the cylinder block 3 via a branch passage 25 branching from the cooling water return passage 23 of the first cooling water return passage 23. Two valves 10 are installed. The second valve 10 is
It is composed of an electromagnetic switching valve that opens and closes in response to a signal from a water temperature sensor 19 provided on the cylinder block 3 side. In this embodiment, the cooling water temperature on the cylinder block 3 side is 80%.
When the temperature is below ℃, the branch passage 25 is closed and the cooling water outlet 16 of the cylinder head 2 is directly communicated with the first radiator 4 side through the first cooling water return passage 23 (hereinafter referred to as the first operating position). When the temperature is 80 ° C. or higher, the branch passage 25 is opened so that the cooling water outlet 16 of the cylinder head 2 communicates with the cooling water inlet 17 of the cylinder block 3 via the branch passage 25 (second operating position). To work. Further, the cooling water outlet 18 of the cylinder block 3 is connected to the first cooling water return passage 23 via the second cooling water return passage 26 and at a position downstream of the mounting position of the second valve 10. .

The cooling device of this embodiment configured as described above operates as follows.

When the operating condition of the engine is in area c or area b
In addition, when the cooling system control condition is not satisfied, that is, knocking is relatively unlikely to occur, so that the cylinder head 2
The first valve 9 is set to the first operating position when less intensive cooling is required. Therefore, the second
The cooling water does not circulate to the radiator 5 and the second radiator 5 is deactivated. In this state,
As shown by the solid line arrow in the figure, the cooling water flowing out from the first radiator 4 is directly supplied to the water pump 6 through the first cooling water supply passage 21, and the walk pump 6 moves to the cylinder head 2. Introduced in the water jacket. The cooling water flowing in the water jacket of the cylinder head 2 exchanges heat with the cylinder head 2, and then flows out from the cooling water outlet 16 to the thermostat 13 side. At this time, if the temperature of the cooling water is 60 ° C. or less, the thermostat 13 opens the bypass passage 24, and the cooling water bypasses the first radiator 4 and flows back to the water pump 6 side as it is, as shown by the solid arrow. And acts to accelerate the warm-up of the engine.

On the other hand, when the water temperature is 60 ° C. or higher, the thermostat 13 closes the bypass passage 24 and the cooling water 62 flows to the first cooling water return passage 23 side. At this time, when the temperature of the cooling water in the water jacket of the cylinder block 3 is 80 ° C or lower, the second valve 10 is set to the first operating position, and the entire amount of the cooling water is the water of the cylinder block 3. The cylinder block 3 is not cooled but flows back to the first radiator 4 side as it is, without flowing into the jacket, as shown by the solid line arrow. Therefore, in this case, the increase in oil viscosity due to the supercooling of the cylinder block 3 and the accompanying increase in the sliding resistance in the sliding portion such as the piston are suppressed.

On the other hand, when the water temperature on the cylinder block 3 side is 80 ° C. or higher, the branch passage 25 is opened by the second valve 10, and the cooling water after passing through the cylinder head 2 is branched as indicated by the broken line arrow.
It is introduced from 25 into the water jacket of the cylinder block 3. Therefore, at the same time as cooling the cylinder head 2,
The cylinder block 3 is also cooled, but in this case as well, since the cooling water flows to the cylinder block 3 side after passing through the cylinder head 2, the cylinder head 2 is cooled more effectively than the cylinder block 3. To be done.

(Area a) When the cooling system control condition is satisfied in the area a or the area b, that is, when the knocking is likely to occur and the cylinder head 2 needs to be cooled more intensively. Causes the first valve 9 to be set in the second actuated position. Therefore, the first radiator 4 and the second radiator 5 are connected in series, and the cooling water passes through the first radiator 4 and then reaches the second radiator 5 as shown by the one-dot chain line arrow. The two radiators, the first radiator 4 and the second radiator 5, dissipate heat in two stages to sufficiently cool them, and then introduce them into the water jacket of the cylinder head 2 via the water pump 6. Therefore, the temperature of the cooling water introduced to the cylinder head 2 side is lower than that in the case of the region c in which only the heat radiation effect of the first radiator 4 can be used.
The cylinder head 2 is cooled more effectively, the mechanical octane number of the engine is improved, and knocking is prevented as much as possible. Further, also in this case, when the temperature of the cooling water on the cylinder block 3 side is 80 ° C. or lower, the cooling water is not introduced to the cylinder block 3 side,
Only when the temperature is 80 ° C. or higher, the cylinder block 3 is cooled by the cooling water, and the increase of the sliding resistance of the engine due to the supercooling of the cylinder block 3 is suppressed.

Incidentally, in this first embodiment, the first radiator 4
Only or first radiator 4 and second radiator 5
From the head side cooling system X to the cylinder head 2 and the water jacket through the water pump 6 and then to the first radiator 4 through the first cooling water return path 23. Only the radiator 4 or the first radiator 4 and the second radiator 5 through the water pump 6 to the water jacket of the cylinder head 2 and further the branch passage 25 through the water jacket of the cylinder block 3 to the second cooling water return passage 26. The block side cooling system Y is constituted by a series of cooling water circulation systems from the first cooling water return path 23 to the first radiator 4.

(Second Embodiment) FIG. 2 shows a cooling system for an automobile engine according to a second embodiment of the present invention. In the cooling device of the first embodiment, two radiators 4 and 5 and one water pump 6 constitute the head side cooling system X and the block side cooling system Y, whereas the cooling system of the first embodiment is 2 Radiators 4,5
A head side cooling system X and a block side cooling system Y are constituted by the two water pumps 7 and 8 respectively corresponding thereto. Specifically, the first radiator 4 and the first water pump 7 provided on the cooling water inlet 15 side of the cylinder head 2.
A first valve 9 in a first cooling water supply passage 21 communicating with
The first cooling water return connecting the cooling water outlet 16 of the cylinder head 2 and the inflow side of the first radiator 4 with the provision of (the same construction and the same function as those of the first embodiment). Thermostat 13 and second valve 10 on line 23
(The same structure and function as those in the first embodiment are provided), and the second valve 10 and the first cooling water inlet 17A of the cylinder block 3 are connected to each other through the branch passage 25 and the cylinder block 3 as well. The first cooling water outlet 18A and the first cooling water return passage 23 are connected by the second cooling water return passage 26, respectively.

Therefore, when the first valve 9 is in the first operating position,
That is, when the operating state of the engine is in the region c or the region b and the cooling system control condition is not satisfied, the first water pump 7
When the temperature of the cooling water on the cylinder block 3 side is 80 ° C. or less, the cooling water discharged from the cooling water flows through the water jacket of the cylinder head 2 to cool it, and then on the cylinder block 3 side. Is directly returned to the first radiator 4 via the first cooling water return passage 23 without being cooled. On the other hand, when the temperature of the cooling water on the cylinder block 3 side is 80 ° C. or higher, the cooling water flows through the water jacket of the cylinder head 2 and then passes through the branch passage 25 and then the water jacket of the cylinder block 3 as shown by the broken line arrow. After flowing into the inside and cooling the cylinder block 3, the second
It is recirculated to the first radiator 4 side via the cooling water return passage 26 and the first cooling water return passage 23.

Further, a radiator connection path 31 for connecting the first radiator 4 and the second radiator 5 via the first valve 9 described above.
Is connected to the second cooling water outlet 18B of the cylinder block 3 via a third cooling water return passage 32 branched from the middle thereof. This third cooling water return path 32 has a third valve
11 are provided. This third valve 11 is the same as the first valve described above.
Like the valve 9 of FIG. 1, its operation is controlled by the engine load and the engine speed, and when the cooling system control condition is not satisfied (that is, the first valve 9 is set to the first operating position and the first valve 9 is set to the first operating position). When the radiator 4 is in direct communication with the first water pump 7), the valve is opened to open the third cooling water return passage 32 (first operating position), and when the cooling system control condition is satisfied. (That is, when the first valve 9 is set to the second operating position and the first radiator 4 and the second radiator 5 are connected in series), the valve is closed and the third cooling water return passage 32 is provided. The operating mode is set so as to close the.

In addition, the second radiator 5 and the first water pump 7
The second cooling water supply passage 22 that connects to and is connected to the second cooling water inlet 17B of the cylinder block 3 via the third cooling water supply passage 33 that branches from the middle thereof. This third
A second water pump 8 is provided in the cooling water supply passage 33, and a fourth valve 12 is provided downstream of the second water pump 8. The fourth valve 12 is also controlled according to the engine load and the engine speed similarly to the first valve 9 and the third valve 11, and the third cooling water is used when the cooling system control condition is not satisfied. Supply path 33
Is opened (first operating position), and when the cooling system control condition is satisfied, the third cooling water supply passage 33 is closed (second operating position) to allow the cooling water discharged from the second water pump 8 to flow back. 35
It acts so as to recirculate back to the second water pump 8 side via.

Therefore, when the operating state of the engine is in the region c or the region b and the cooling system control condition is not satisfied, the cooling water discharged from the second water pump 8 is the third cooling water supply passage 33 as indicated by the one-dot chain line arrow. From the inside into the water jacket of the cylinder block to cool the cylinder block 3 and then through the third cooling water return passage 32 to the second radiator 5
Is returned to the side.

On the other hand, when the operating condition of the engine is cooling a or region b and the cooling system control condition is satisfied, that is, when the cylinder head 2 needs to be cooled intensively, the radiator connection path is provided.
31 is opened, the second cooling water return passage 32 is closed, and the third cooling water supply passage 33 is provided by the fourth valve 12.
Is closed, the cooling water discharged from the second water pump 8 is circulated in the recirculation path 35 as shown by the two-dot chain line arrow, and is not discharged to the cylinder block 3 side. This is because the second water pump 8 is usually a mechanical pump and is rotating regardless of whether it is necessary to operate the engine while the engine is operating, so that the operation is disabled and the first radiator 4 and the first radiator 4 and It is provided in order to prevent the cooled cooling water after passing through the second radiator 5 from flowing into the third cooling water supply passage 33 side.
When the water pump 8 is constituted by an electrically controlled pump, the fourth valve 12 and the return passage 35 are unnecessary.

On the other hand, the cooling water discharged from the first water pump 7 is introduced into the first water pump 7 through the second radiator 5 as shown by the broken line arrow, and the cooling water is discharged from the first water pump 7 to the cylinder head. 2 flows into the water jacket side to cool it, and when the water temperature on the cylinder block 3 side is 80 ° C or lower, it does not flow to the cylinder block 3 side and directly to the first cooling water return path 23 side. , Again 80 ℃
In the above case, the water jacket of the cylinder block 3 is circulated to cool the water jacket, and then the second cooling water return path is provided.
After passing through the first cooling water return path 23 side through 26, passing through the first radiator 4 and the second radiator 5 in sequence, each of them performs heat radiation, and then again the second cooling water supply path. It is sucked from 22 to the first water pump 7 side. That is, in this case, since the cooling water radiated in two stages in the first radiator 4 and the second radiator 5 is introduced into the water jacket of the cylinder head 2, it is different from the case of the first embodiment. In the same manner, a high level of cylinder head cooling efficiency is realized, which improves the mechanical octane number of the engine and prevents knocking as much as possible.

The first water pump 7 and the second water pump 8
During this period, the discharge amount of the first water pump 7 is set to be larger than that of the second water pump 8.

In this embodiment, only the first radiator 4 or the first radiator 4 and the second radiator 5 reach the water jacket of the cylinder head 2 and the first cooling water return path 23 to the first radiator 4. The head side cooling system X is composed of a series of cooling water circulation systems that flow back to the 4 side, and from the first radiator 4 and the second radiator 5 to the water jacket of the cylinder block 3 via the water jacket of the cylinder head 2. Further, the cooling water circulation system reaching the first radiator 4 via the second cooling water return path 26 and the first cooling water return path 23 and the second radiator 5
From the second water pump 8 to the cylinder block 3
Third water cooling return path to the water jacket
A block side cooling system Y is constituted by two cooling water circulation systems of a cooling water circulation system which is refluxed from 32 to the second radiator 5.

(Effects of the Invention) A cooling device for a water-cooled engine according to the present invention is a water-cooled engine including a head side cooling system for cooling a cylinder head of an engine and a block side cooling system for cooling a cylinder block. And a second radiator are provided, and only the first radiator is connected in series in the high speed / high load range of the engine, and the first radiator and the second radiator are connected in series in the low speed / high load range of the engine. The cooling water, which has passed through both the first radiator and the second radiator, is sequentially circulated from the cylinder head side cooling system toward the block side cooling system. Is.

Therefore, according to the cooling system for a water-cooled engine of the present invention, (1) two radiators are connected in series in a low speed / high load region where knocking is most likely to occur, and these two radiators perform heat radiation cooling in two stages. Since the cooled water is first supplied to the head side cooling system, the cooling performance for the cylinder head is improved as compared with the case where the cooling water is radiated by only one radiator and is supplied to the head side cooling system. As a result, the mechanical octane number of the engine is increased and knocking is effectively prevented. (2) Cooling water with a relatively high water temperature after cooling the cylinder block in the head side cooling system in the low speed and high load range. Is supplied to the block side cooling system to cool the cylinder block, so that the cylinder block is not overcooled. It can be effectively prevented, and the increase of sliding resistance in the sliding part of the engine due to overcooling of the cylinder block can be effectively suppressed. Therefore, the fuel efficiency and output performance of the engine can be improved. The effect can be obtained.

[Brief description of drawings]

FIG. 1 is a cooling system system diagram of a cooling device for a water-cooled engine according to a first embodiment of the present invention, and FIG. 2 is a cooling system system of a cooling device for a water-cooled engine according to a second embodiment of the present invention. 3 and 4 are control area diagrams of the cooling device. 1 …… Engine 2 …… Cylinder Head 3 …… Cylinder Block 4 …… First Radiator 5 …… Second Radiator 6,7,8 …… Water Pump 9,10,11,12 …… Valve 13 …… Thermostat 15 …… Cooling water inlet 16 …… Cooling water outlet 17A, 17B …… Cooling water inlet 18A, 18B …… Cooling water outlet 19 …… Water temperature sensor

Front Page Continuation (72) Inventor Takaji Soto 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) References: 62-160735 (JP, U) 52-5144 (JP) , U) Actually open Sho 56-31623 (JP, U) Actually open Sho 63-156414 (JP, U)

Claims (1)

[Claims] 1. A water-cooled engine having a head side cooling system for cooling a cylinder head of an engine and a block side cooling system for cooling a cylinder block, wherein a first radiator and a second radiator are provided, and the engine is provided. In the high speed / high load region of the engine, only the first radiator is connected, and in the low speed / high load region of the engine, the first radiator and the second radiator are connected in series and the first radiator and the second radiator are connected in series. The cooling device for a water-cooled engine is configured so that the cooling water after passing through both the radiators is sequentially circulated from the cylinder head side cooling system to the block side cooling system.