JPH01106919A - Cooling device of engine - Google Patents

Abstract

PURPOSE:To reduce any cooling loss and improve fuel consumption by connecting a branch conduit having a thermostat valve for setting high temperature in parallel to a branch conduit having a thermostat valve for setting low temperature and a switching valve for releasing itself under high loads. CONSTITUTION:A cooling water conduit 3x between the exit side of an engine 1 and a radiator 2 is divided on its way into the first branch conduit 3a and the second branch conduit 3b. A bypass conduit 7 is communicated to the first branch conduit 3a on the direct upstream side of a thermostat valve 5 for setting thigh temperature (about 100 deg.C). A thermostat valve 6 for setting low temperature (about 82 deg.C) is provided in the second branch conduit 3b and a switching valve 9 is arranged in series on the downstream side thereof. The switching valve 9 is controlled by means of ECU 16 provided with a load sensor 17 connected thereto and vacuum is introduced during high load operation via a three way solenoid valve 14 in order that the second branch conduit 2b is released.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an improvement in an engine cooling system equipped with a thermostatic valve in a cooling water passage between an engine and a radiator. Concerning stabilization measures.

(Prior art) Generally, in this type of engine cooling system, when the opening temperature of the thermostat valve is set high, relatively high temperature cooling water bypasses the radiator and circulates to the engine, so cooling This has the advantage of reducing losses and improving fuel efficiency.

On the other hand, when the opening temperature of the thermostat valve is set high as described above, when the engine is temporarily operated at a high load, the thermostat valve maintains its closed state due to its responsiveness, so the wall temperature of the cylinder block increases. This may lead to a sudden increase in the amount of water, raising concerns about decreased durability.

Therefore, in order to improve fuel efficiency while ensuring good engine cooling performance, for example, a thermostatic valve with a high opening temperature is provided in the cooling water passage, and a bypass passage is provided to bypass the thermostat valve. By providing an on-off valve in the bypass passage that opens when the engine is under high load, the bypass passage is closed when the engine is under low load, and the cooling water temperature is maintained relatively high based on the opening and closing operation of the thermostat valve, improving fuel efficiency. Along with planning,
When the engine is under high load, the opening operation of the on-off valve allows cooling water to flow through the bypass passage to the radiator even when the thermostat valve is closed, suppressing a sudden rise in cylinder block wall temperature and ensuring good engine durability. It is possible that

However, when simply providing an on-off valve as described above, this on-off valve is usually composed of a butterfly valve or a reciprocating on-off valve, and when the former is used, the inner wall of the bypass passage and the outer circumference of the valve are Cooling water leaks from the gap between the parts. Furthermore, in the case of the latter configuration, although no gap is created, the valve may open temporarily due to pressure fluctuations or vibrations of the cooling water, and the cooling water similarly leaks. Therefore, due to the leakage of cooling water, the warm-up performance of the engine deteriorates, especially when the engine is being warmed up.

Therefore, in addition to the above-mentioned on-off valve, a thermostatic valve separate from the above-mentioned thermostatic valve with a high opening temperature is provided.
The opening temperature of the thermostatic valve is set to a temperature lower than the opening temperature of the thermostatic valve, and the good sealing properties of the thermostatic valve prevent leakage of cooling water from the opening/closing valve, while at the time of low engine load, When the on-off valve closes, the thermostatic valve on the high-temperature setting side starts circulating cooling water to the radiator, improving fuel efficiency. On the other hand, when the engine is under high load, the thermostatic valve on the low-temperature setting side starts circulating cooling water to the radiator based on the open state of the on-off valve. It is conceivable to start the circulation of cooling water to suppress the sudden rise in the wall temperature of the cylinder block.

Therefore, based on the above idea, conventionally, for example,
4-9665, a thermostat valve on the high-temperature setting side and a thermostat valve on the low-temperature setting side are provided in series in a cooling water passage, and a bypass passage is provided to bypass the thermostat valve on the high-temperature setting side. By interposing an on-off valve that opens when the engine is under high load in the bypass passage, the sealing performance of the on-off valve is compensated by a thermostatic valve on the low-temperature setting side, and a sudden rise in the wall temperature of the cylinder block is prevented when the engine is under high load. While effectively suppressing the opening operation of the on-off valve to ensure good engine cooling performance, the cooling water temperature is maintained at a relatively high temperature to improve fuel efficiency.

(Problems to be Solved by the Invention) However, in the above conventional system, when the engine is under low load and the cooling water temperature is high, for example, when transitioning from high speed and high load conditions to low speed operation or stopping, the running wind Although it is difficult to enter the radiator, the amount of heat dissipated from the radiator decreases, and the temperature of the cooling water rises rapidly.However, at this time, the on-off valve is in the closed state, so the bypass passage is closed, and the cooling water is
It circulates between the radiator and the engine via several thermostatic valves. As a result, these two thermostat valves act as resistance to the flow of cooling water, reducing the amount of circulating water and resulting in insufficient engine cooling performance.

The present invention has been made in view of these points, and its purpose is to provide a separate thermostat valve for low temperature setting in addition to the thermostat valve and on-off valve for high temperature setting as described above. By arranging the thermostatic valves in parallel in the cooling water passage instead of in series, when the engine load is low and the cooling water temperature is high, the cooling water can flow to the radiator through only one thermostatic valve. This reduces the flow resistance of the coolant and increases the amount of coolant circulated accordingly, ensuring good engine cooling at all times.The thermostat valve on the low temperature setting side compensates for the sealing of the opening/closing valve. At the same time, the objective is to maintain the cooling water temperature at a relatively high temperature to improve fuel efficiency.

-6= (Means for solving the problem) In order to achieve the above object, the solution of the present invention provides a plurality of thermostatic valves with different opening temperatures in the cooling water passage between the engine and the radiator. At the same time, with a control valve such as an on-off valve, when the engine is under low load, the thermostatic valve on the high temperature setting side where the valve opening temperature is high starts the circulation of cooling water to the radiator, while when the engine is under high load, the cooling water circulation is started on the low temperature setting side where the valve opening temperature is low. The subject matter is an engine cooling system in which a thermostatic valve starts circulating cooling water to a radiator. In the middle of the cooling water passage, the same number of branch cooling water passages as the thermostat valves are provided in parallel, each branch cooling water passage is provided with the plurality of thermostat valves, and the thermostat valve on the low temperature setting side is provided. The above-mentioned control valve is provided in the provided branch cooling water passage.

(Function) With the above configuration, in the present invention, when the engine load is low, the cooling water does not flow to the branch cooling water passage provided with the thermostatic valve on the low temperature setting side by closing the control valve such as the on-off valve. Cooling water circulation to the radiator was provided in another branch cooling water passage. Since the operation is started by the thermostat valve on the high-temperature setting side with a high valve opening temperature, the cooling water temperature can be maintained high to the high-temperature side valve opening temperature, reducing cooling loss and improving fuel efficiency.

On the other hand, when the engine is under high load, the opening operation of the control valves such as the above-mentioned on-off valves allows the cooling water to flow through the branched cooling water passage provided with the thermostatic valve on the low-temperature setting side, and the cooling water circulation to the radiator is interrupted by this opening. Since it is started by the thermostatic valve on the low temperature setting side where the valve temperature is low, a sudden increase in the wall temperature of the cylinder block of the engine is suppressed as much as possible, and good durability of the engine is ensured.

In addition, in each branch cooling water passage, cooling water leakage is reliably prevented due to the good sealing properties of the plurality of thermostat valves installed in each cooling water passage, so especially when the engine is warmed up, Warm-up performance is improved.

Furthermore, since the plurality of thermostat valves are each arranged in parallel branch cooling water passages, when the engine load is low, when the control valves such as the on-off valves are closed, the low-temperature setting side When the cooling water is at high temperature, it flows to the radiator only through the branch cooling water passage equipped with the thermostat valve on the high temperature setting side, so the thermostatic valve on the low temperature setting side is Because of this, the flow resistance of the coolant is reduced, the amount of coolant circulated is increased, and engine cooling performance can be improved.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an overall schematic configuration of an engine cooling device according to an embodiment of the present invention. In the figure, 1 is an engine, 2 is a radiator provided in front of the engine 1, 3 is a cooling water passage that communicates and connects the engine 1 and the radiator 2, and a water pump is installed in the middle of the cooling water passage 3. 4 is interposed, and after the water pump 4 circulates low-temperature cooling water to the engine 1 as shown by the arrow in the figure, it passes through the cooling water passage 3x on the outlet side (upper side in the figure) to the radiator 2.
The cooling water is cooled by flowing through the cooling water passageway 3Y on the engine inflow side, and then passed through the engine 1 again through the cooling water passage 3Y on the engine inflow side.

Thus, the cooling water passage 3x between the engine 1 outlet side and the radiator 2 is connected to the first branch cooling water passage 3 midway therebetween.
a and a second branch cooling water passage 3b, each branch cooling water passage 3a, 3b is provided with a thermostat valve 5, 6, respectively. A bypass passage 7 that communicates with the cooling water passage 3Y upstream of the water pump 4 is connected to the cooling water passage 3a immediately upstream of the thermostat valve 5.

The thermostatic valve 5 of the first branch cooling water passage 3a is
As shown in detail in FIG. 2, there is a temperature sensing part 5a made of wax that expands and contracts by sensing the temperature of the cooling water;
A valve body 5c whose one end is inserted into the upper part and opens and closes the valve seat 5b, and a spring 5d which biases the valve body 5C in the valve closing direction.
It has a rod 5e connected to the temperature sensing section 5a and protruding downward as the wax expands, and a valve body 5f provided at the lower end of the rod 5e to open and close the bypass passage 7. The opening temperature of the thermostatic valve 5 is set to a relatively high set temperature T+-+ (for example, 100° C.). Therefore, when the temperature of the cooling water flowing through the first branch cooling water passage 3a is lower than the set temperature TH (100°C), the valve body 5c is moved upward by the contraction operation of the temperature sensing portion 5a, and the valve body 5c is closed. It is seated on the seat 5b to close the first branch cooling water passage 3a, to prevent the cooling water from the engine 1 from flowing to the radiator 2 through the first branch cooling water passage 3a, and to prevent the cooling water from flowing over the valve body 5C. As the lower valve body 5r moves
moves upward to open the bypass passage 7 and circulate the cooling water from the engine 1 through the bypass passage 7 to the engine 1. On the other hand, if the temperature of the cooling water flowing through the first branch cooling water passage 3a exceeds the set temperature TH (100°C),
As the temperature sensing part 5a expands, the valve body 5C is moved by the spring 5.
It moves downward against the biasing force of d, moves away from the valve seat 5b, and operates to open, increasing the passage area of the first branched cooling water passage 3a and allowing the cooling water to flow into the radiator 2. At the same time, the lower valve body 5f is configured to move downward as the temperature sensing portion 5a expands, thereby reducing the passage area at the end of the bypass passage 7 and reducing the flow rate to the bypass passage 7. There is.

On the other hand, the thermostatic valve 6 of the second branch cooling water passage 3b, like the thermostatic valve 5 described above, includes a temperature sensing part 6a that responds to the temperature of the cooling water, and a valve seat 6 attached to the temperature sensing part 6a.
It has a valve body 6C that opens and closes the valve body 6C, and a spring 6d that biases the valve body 6c in the valve closing direction. The opening temperature of the thermostatic valve 6 is determined by the first branch cooling water passage 3.
Opening temperature TH of thermostatic valve 5 of a (100°C)
The set temperature TL (for example, 82° C.) is set on the lower temperature side and is approximately the same value as the conventional one. Therefore, the temperature of the cooling water flowing through the second branch cooling water passage 3b is the set temperature TL.
(82° C.) or lower, the valve body 6C is seated on the valve seat 6b to close the second branch cooling water passage 3a and prevent the cooling water from flowing into the radiator 2. When the temperature of the cooling water flowing through the cooling water passage 3b exceeds the set temperature TL (82° C.), the valve body 6c separates from the valve seat 6b due to the expansion of the temperature sensing portion 6a and operates to open the second valve. The passage area of the branched cooling water passage 3b is increased to allow cooling water to flow into the radiator 2.

Further, in the second branch cooling water passage 3b, the second branch cooling water passage 3b is provided downstream of the thermostat valve 6 on the low temperature setting side that opens at the set temperature TL (82°C) as described above. A reciprocating on-off valve 9 is provided as a control valve that opens and closes the branch cooling water passage 3b. The on-off valve 9 is
It has a valve body 9a that collects dust on a valve seat 3K provided in the second branch cooling water passage 3b, and is connected to the diaphragm device 10 via a rod 9b. The diaphragm device 10 is partitioned into two pressure chambers 12a and 12b by a diaphragm 11 to which the rod 9b is connected, and a spring 12c is compressed in the lower pressure chamber 12b, and the lower pressure chamber 12b is compressed. The chamber 12b communicates with an intake passage (not shown) downstream of the throttle valve of the engine 1 via a negative pressure passage 13. Furthermore, as shown in FIG. 1, a three-way solenoid valve 14 and a one-way valve 15 are interposed in the middle of the negative pressure passage 13 on the intake passage side. The operation of the three-way solenoid valve 14 is controlled by an ECU 16, and an engine load signal from a load sensor 17 that detects the load state of the engine 1 is input to the ECU 16. Then, the ECU 1B, when the engine is under low load,
It has a function of controlling the operation of the three-way solenoid valve 14 so that the intake negative pressure downstream of the throttle valve is introduced into the pressure chamber 12b, and when the engine is under high load, atmospheric pressure is introduced into the pressure chamber 12b.

With the above configuration, when the engine load is low, the diaphragm 11 is biased downward against the spring 12c by introducing negative pressure into the pressure chamber 12b of the diaphragm device 10, and accordingly, the valve body 9a of the on-off valve 9 is biased downward. Move the valve seat 3K
and close the second branch cooling water passage 3b. on the other hand,
When the engine is under high load, atmospheric pressure is introduced into the pressure chamber 12b, and the diaphragm 11 is biased upward by the biasing force of the spring 12c, causing the valve body 9a of the on-off valve 9 to separate from the valve seat 3K. It is configured to open a two-branch cooling water passage 3b.

Further, 18 is a water temperature sensor that detects the temperature of the cooling water in the cooling water passage 3x on the engine outlet side, and the water temperature signal is inputted to the ECU 1B.

Based on the output signal of the water temperature sensor 18, the ECU 16 determines whether the cooling water temperature on the engine outlet side is equal to or less than the first temperature.
Opening temperature T of thermostatic valve 5 of branch cooling water passage 3a
When the temperature reaches 106°C or higher, which is higher than H (100°C) by a predetermined value (for example, 6°C), the pressure chamber 12b of the diaphragm device 10 is closed regardless of the load condition of the engine 1.
Three-way solenoid valve 14 to forcefully introduce atmospheric pressure into the
When the cooling water temperature reaches a high temperature (106°C) or higher, the on-off valve 9 is forcibly opened and the radiator 2 is also supplied from the second branch cooling water passage 3b. A control means 19 is configured to allow cooling water to flow through the engine, increase the flow rate of the cooling water accordingly, and improve engine cooling performance.

In addition, in the first branch cooling water passage 3a and the second branch cooling water passage 3b, the length dl of the constricted portion of the former,
The length dl of the latter aperture portion is d as shown in FIG.
, <d2, and when the engine load is low with the on-off valve 9 closed, even if the cooling water temperature exceeds the valve opening temperature TH (100°C) of the thermostatic valve 5 on the high temperature setting side. , the forcible opening operation temperature of the on-off valve 9 (
106°C), as the on-off valve 9 closes,
With the first branch cooling water passage 3a having a narrow passage area,
The flow rate of cooling water to the radiator 2 is limited to a small amount to maintain the temperature of the cooling water as high as possible, thereby improving the effect of reducing fuel consumption.

Further, in FIG. 1, reference numeral 20 denotes a heater passage that returns part of the cooling water in the engine 1 to the upstream side of the water pump 4. In the middle of the heater passage 20, there is a heater 21 that heats and air-conditions the interior of the vehicle. , the heater passage 2 on the downstream side of the heater 21
Two on-off valves 22 and 23 are interposed to control the opening and closing of 0. The one on-off valve 22 is ON-OF of the heater 21.
The other on-off valve 23 is used for F control, and is closed when the on-off valve 9 is opened to circulate the entire amount of cooling water to the radiator 2, thereby improving engine cooling performance.

Therefore, in the above embodiment, when the engine 1 is under low load, the temperature of the cooling water is the set temperature T+(
100°C) or lower, the thermostat valve 6 on the low temperature setting side is in the open state when the cooling water temperature exceeds the valve opening temperature TL (82°C), but the on-off valve 9 is closed. The second branch cooling water passage 3b is closed. Further, the thermostat valve 5 on the high temperature setting side is in a closed state, thereby closing the cooling water passage 3x on the engine outlet side and opening the bypass passage 7. As a result, all the cooling water from the engine 1 flows through this bypass passage 7 and returns to the engine 1, and as a result, the temperature of the cooling water rises to the set temperature TH (100°C) on the high temperature side. As a result, cooling loss is reduced and fuel efficiency is improved.

On the other hand, when the engine 1 is under high load, the on-off valve 9 becomes = 17.
− Operates to open. As a result, the flow of cooling water between the engine 1 and the radiator 2 is started at the thermostatic valve 6 on the low temperature setting side. In this case, the set temperature TL (
When the temperature is lower than 82°C, the thermostat valve 6 on the low temperature setting side is in the closed state;
2° C.) is the same value as in the past, there is little risk of a sudden rise in the wall temperature of the cylinder head. Furthermore, when the cooling water temperature exceeds the set temperature TL (82°C) on the low-temperature side, there is a strong concern that the wall temperature of the cylinder head will rise rapidly even when the set temperature T)-1 (100°C) on the high-temperature side is below. However, at this time, the thermostat valve 6 on the low temperature setting side is opened, and the cooling water flows through the second branch cooling water passage 3b to the radiator 2 and is properly cooled, so that the wall temperature of the cylinder head decreases. Rapid rise is effectively prevented, and the durability of the engine 1 is ensured well.

Furthermore, when the engine 1 is under low load, the on-off valve 9 is in a closed state, but since its structure is of a reciprocating type, it may open temporarily due to fluctuations in the pressure of the cooling water. , the second branch cooling water passage 3b on the upstream side thereof
Since the thermostat valve 6 on the low-temperature setting side is arranged in The good sealing performance of the thermostatic valve 6 compensates for the sealing performance of the above-mentioned on-off valve 9.

In addition, the thermostat valve 5 on the high temperature setting side is provided in the first branch cooling water passage 3a, and the thermostat valve 6 on the low temperature setting side is provided in the second branch cooling water passage 3a, which is in parallel relationship with the opening/closing valve 9. Since it is provided in the branch cooling water passage 3b, when the engine load is low, the on-off valve 9 is closed.
The temperature of the cooling water is set at the high temperature side TH (100℃
), the first branch cooling water passage 3 passes through only the thermostat valve 5 on the high temperature setting side which is in the open state.
The amount that flows from a to the radiator 2 without passing through the thermostatic valve 6 on the low temperature setting side,
The flow resistance of cooling water can be reduced, and engine cooling performance can be improved.

Moreover, the cooling water temperature is the set temperature TH (100℃) on the high temperature side.
), if the temperature reaches 106°C or higher,
Regardless of the load condition of the engine 1, the on-off valve 9 is controlled by the control means 1.
9 forcibly opens the first branch cooling water passage 3.
Since the second branch cooling water passage 3b is opened together with the second branch cooling water passage 3b, the flow rate of cooling water to the radiator 2 is increased, and the engine cooling performance is further improved.

In the above embodiment, the actuator of the on-off valve 9 is constituted by a diaphragm device 10 and is operated mechanically to open and close, but it is of course possible to open and close electrically.

(Effects of the Invention) As explained above, according to the engine cooling system of the present invention, one of the branch cooling water passages arranged in parallel is provided with a thermostatic valve on the high temperature setting side with a high valve opening temperature. At the same time, we installed a control valve that opens when the engine is under high load, and a low-temperature setting thermostat valve that opens at a lower opening temperature than the above-mentioned thermostat valve, in the other branch cooling water passages, so that it can be opened during high-load engine operation. A sudden rise in the wall temperature of the cylinder block is effectively prevented by the flow of cooling water to the radiator based on the opening operation of the control valve, ensuring good engine durability while maintaining the sealing performance of the control valve on the low-temperature setting side. While compensating with the thermostat valve, the temperature of the engine cooling water can be maintained as high as possible by the thermostat valve on the high temperature setting side, thereby reducing cooling loss and improving fuel efficiency. Moreover, when the engine is under low load and the cooling water temperature exceeds the set temperature on the high temperature side, the engine cooling water is passed through the radiator only through the thermostat valve on the high temperature side, and does not flow through the thermostat valve on the low temperature side. , the flow resistance of cooling water can be reduced, and engine cooling performance can be improved.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, with FIG. 1 being a general schematic diagram, and FIG. 2 being a specific diagram showing the main parts of FIG. 1. 1... Engine, 2... Radiator, 3... Cooling water passage, 3a... First branch cooling water passage, 3b... Second branch cooling water passage, 5... High temperature setting side Thermostat valve, 6... Thermostat valve on high temperature setting side, 9...
- Opening/closing valve, 10...Diaphragm device, 14...Three-way solenoid valve, 16...ECU, 19...Control means.

Claims (2)

[Claims] (1) Cooling water is circulated to the radiator by multiple thermostatic valves with different opening temperatures installed in the cooling water passage between the engine and the radiator, and when the engine is under low load, the thermostatic valve on the high-temperature setting side has a higher opening temperature. The engine cooling device is equipped with a control valve that starts cooling water circulation to the radiator by a thermostat valve on the low-temperature setting side with a low valve opening temperature when the engine is under high load, and a control valve that starts cooling water circulation to the radiator. is a branch cooling system in which the same number of branch cooling water passages as the thermostat valves are provided in parallel, each of the branch cooling water passages is provided with the plurality of thermostat valves, and the thermostat valve on the low temperature setting side is provided. An engine cooling device characterized in that a water passage is provided with the above control valve. (2) The control valve is an engine equipped with a control means that forcibly opens the control valve when the cooling water temperature reaches a predetermined value higher than the opening temperature of the thermostat valve on the high temperature setting side. cooling system.