JP3240791B2 - Internal combustion engine cooling system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling system for a water-cooled internal combustion engine, and more particularly to control of a cooling water temperature.

[0002]

2. Description of the Related Art Water temperature control of a conventional water-cooled internal combustion engine is automatically performed by a thermostat and is set substantially constant regardless of operating conditions.

[0003]

However, when the load is low, it is necessary to improve the fuel efficiency by setting the cooling water temperature to a higher temperature. The reason for this is that the oil temperature in the internal combustion engine rises with the cooling water temperature, so the higher the cooling water temperature, the higher the oil temperature, and accordingly, the friction (friction)
And the increase in temperature causes an increase in fuel atomization and a decrease in the quench area due to an increase in the bore wall temperature, thereby improving combustion efficiency.

On the other hand, when the load is high, if the temperature is set lower than the cooling water temperature, knocking can be suppressed and the output can be improved by improving the charging efficiency. By the way, Japanese Patent Laid-Open No.
As shown in Japanese Patent Publication No. 13, part of the cooling water entering the engine is sucked out by an external pump and sent to the radiator. The cooling water is not heated by not entering the engine, and is returned to the radiator again. There is something. Since the cooling water is returned to the radiator without passing through the engine, according to this structure, the temperature of the water at the outlet of the radiator surely falls.

[0005] However, since the temperature of the water is controlled to be substantially constant by the thermostat, the temperature of the water entering the engine does not change. In addition, since the amount of cooling water passing through the inside of the engine decreases steadily, the difference in water temperature between the inlet and outlet of the engine increases, which contributes to an imbalance in the wall temperature distribution of the engine, which not only reduces the output but also reduces And may degrade reliability.

Accordingly, the present invention provides a cooling device for an internal combustion engine which can raise the cooling water temperature at a low load and lower the cooling water temperature at a high load without changing the amount of water passing through the inside of the internal combustion engine. The purpose is to:

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a heat exchanger for cooling cooling water of an internal combustion engine and a cooling water flowing out of the internal combustion engine to the heat exchanger. A cooling water passage for introducing cooling water cooled by the heat exchanger into the internal combustion engine, and cooling water flowing out of the internal combustion engine, which is disposed in parallel with the cooling water passage and flows around the heat exchanger. Then, a first bypass flow path that flows out to the cooling water passage downstream of the heat exchanger, and the first bypass flow passage is connected to the cooling water passage downstream of the heat exchanger. A flow control valve disposed at a position, detecting a cooling water temperature, adjusting a ratio of a flow rate flowing through each of the cooling water passage and the bypass flow passage according to the cooling water temperature, and provided in the middle of the cooling water passage. A pump for cooling water circulation, and a load state of the internal combustion engine. And a second bypass flow passage through which cooling water flows in the middle of the first bypass flow passage and flows out to the cooling water passage between the flow control valve and the internal combustion engine. And a state in which the state of the internal combustion engine detected by the load state detecting means is lower than a predetermined load in a position in the middle of the first bypass path where the second bypass path is connected. When in a low load state, more cooling water flows into the second bypass flow path than the first bypass flow path, and the state of the internal combustion engine detected by the load state detection means is equal to or more than a predetermined load. When the engine is in a high load state, a cooling device for an internal combustion engine including a flow control valve that allows more cooling water to flow into the first bypass flow path than the second bypass flow path is employed.

According to the second aspect of the present invention, the load state detecting means detects a negative pressure in an intake pipe for supplying an air-fuel mixture to the internal combustion engine, and the flow control valve detects the negative pressure. The cooling device for an internal combustion engine according to claim 1, wherein the distribution of the flow rate is adjusted according to the following. Further, according to the present invention, the internal combustion engine is a water-cooled internal combustion engine having an intake-side pre-cooling passage, wherein the internal combustion engine has a cooling water discharge side and an intake-side pre-cooling passage. 3. The internal combustion engine according to claim 1, further comprising a third bypass passage connecting the downstream side to the downstream side, wherein the cooling water flows into the bypass passage when the cooling water is warmed up to a predetermined temperature or lower. Is adopted.

Further, according to the present invention, there is provided a water temperature detecting means for detecting a temperature of the cooling water, and when the temperature detected by the water temperature detecting means is equal to or higher than a predetermined temperature, the flow rate of the cooling water is reduced. 2. The control valve allows more cooling water to flow into the first bypass flow path than the second bypass flow path. 3.
According to a third aspect of the present invention, there is provided a cooling device for an internal combustion engine.

Further, according to the present invention as set forth in claim 5,
2. The cooling device for an internal combustion engine according to claim 1, wherein the second bypass flow path passes through intake air heating means provided in an intake pipe of the internal combustion engine.

[0011]

According to the cooling device for an internal combustion engine of the present invention having the above structure, the load state of the internal combustion engine is detected by the load state detecting means. When the load state is a low load state, the flow control valve is set to the first state. The cooling water flowing into the second bypass flow path is made larger than the cooling water flowing into the second bypass flow path.
Then, much of the cooling water flows into the internal combustion engine by bypassing the flow control valve disposed at the position where the first bypass flow passage and the cooling water passage are connected. At this time, the cooling water heated by the internal combustion engine flows only a little to the temperature sensing part of the flow control valve, the temperature of the cooling water near the temperature sensing part of the flow control valve becomes low, and the flow control valve Stable on valve closing side. Therefore, the flow rate of the cooling water flowing while bypassing the heat exchanger for cooling the cooling water heated by the internal combustion engine is large, and the flow rate cooled by the heat exchanger is reduced, resulting in a high water temperature.

On the other hand, when the load state of the internal combustion engine detected by the load state detecting means is a high load state, the flow regulating valve removes most of the cooling water flowing into the first bypass flow passage as it is to the first bypass passage. To the bypass flow path. Therefore, the temperature sensing part of the flow control valve can directly receive the temperature of the cooling water heated by the internal combustion engine. Therefore, the temperature of the cooling water near the temperature sensing part of the flow control valve becomes high, and the flow control valve is stabilized on the valve opening side. Therefore, the flow rate of the cooling water flowing in the cooling water passage increases, and the flow rate cooled by the heat exchanger increases. At this time, since the flow rate of the cooling water flowing while bypassing the heat exchanger is reduced, the water temperature becomes low.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a cooling device for an internal combustion engine according to the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram of the first embodiment. As shown in FIG. 1, a cooling device 10 for an internal combustion engine according to the present invention includes an engine 11 as an internal combustion engine, and a radiator 15 as a heat exchanger for heat radiation with the engine 11.
And a bypass flow path 13 arranged in parallel with the cooling water path 12 and bypassing the radiator 15.
And a thermostat 14 as a flow control valve disposed in the middle of the cooling water passage 12 to control the flow distribution according to the temperature.
, A pump 16 for circulating cooling water, and a bypass passage 1
The flow control valve 19 switches the cooling water from 3 to a first water conduit 17 which is a part of the bypass flow channel 13 and a second water conduit 18 corresponding to the second bypass flow channel.

The flow regulating valve 19 is disposed at the downstream end 131 of the bypass passage 13. This flow regulating valve 19
Forms a diaphragm chamber 197 between the casing 196 and the diaphragm 191, and a spring 19
2 is provided. In the lower part of the diaphragm 191, a cylindrical driving force transmitting portion 193 is provided at an end of the driving force transmitting portion 193, and a communication hole 171 or the bypass flow passage 13 between the bypass flow passage 13 and the first water conduit 17 is provided. And the second headrace 1
And a valve body 194 capable of opening and closing a communication hole 181 with the valve 8. The diaphragm chamber 197 is communicated with an intake pipe (not shown, hereinafter referred to as an intake manifold), and the valve body 194 moves up and down by the negative pressure of the intake manifold.

The first water conduit 17 is disposed between the switching valve 19 and the thermostat 14, and the cooling water flowing into the first water conduit 17 from the bypass passage 13 hits the temperature sensing part of the thermostat 14. Spilled to. On the other hand, the second water conduit 18 is disposed between the flow control valve 19 and the cooling water channel 12 between the thermostat 14 and the pump 16, and the cooling water flowing into the second water conduit 18 from the bypass flow passage 13. The water flows into the pump 16 by bypassing so as not to hit the temperature sensing part of the thermostat 14.

Next, the operation of this embodiment will be described.
When the engine 11 is operated at a low load, a large negative pressure acts in the diaphragm chamber 197 of the flow control valve 19 because the negative pressure of the intake manifold is large, and a pressure higher than a predetermined pressure is applied to the diaphragm chamber 197. Then, the valve body 194 is pulled up overcoming the spring 192.

As a result, most of the cooling water passing through the bypass passage 13 is sucked by the pump 16 through the second water conduit 18 and returned to the engine 11. Second headrace 1
The cooling water that has passed through 8 does not hit the temperature sensing part of the thermostat 14, so that the thermostat 14 is stable on the valve closing side,
As a result, the cooling water temperature is maintained at a high temperature. On the other hand, when the engine 11 is operated in a state of a high load instead of a low load, the negative pressure of the intake manifold is reduced to a pressure lower than a predetermined pressure because the negative pressure of the intake manifold is reduced.
Descends, most of the cooling water passing through the bypass passage 13 passes through the first water conduit 17, hits the temperature sensing part of the thermostat 14, and is sucked by the pump 16.

As a result, the high-temperature cooling water in the bypass passage 13 hits the temperature sensing portion of the thermostat 14, so that the thermostat 14 is stabilized on the valve opening side, and the temperature of the cooling water is maintained at a low temperature. In addition, since the flow control valve 19 can continuously change the distribution of the amount of cooling water passing through each of the first water passage 17 and the second water passage 18 according to the negative pressure of the intake manifold,
When changing from low load to high load, or from high load to low load, set water temperature from high water temperature to low water temperature,
Alternatively, the temperature can be smoothly changed from the low water temperature to the high water temperature, and the drivability does not deteriorate.

Next, a second embodiment of the present invention will be described. FIG. 2 shows a configuration diagram of the present embodiment. In the first embodiment, a VSV (vacuum switching valve) 9 is installed in the middle of a pipe connecting the inside of the diaphragm chamber 197 of the flow rate control valve 19 and the intake manifold, and is controlled by a CPU 21 which is an arithmetic processing unit. Drive. The output of the water temperature sensor 22 for detecting the temperature of the cooling water discharged from the engine 11 is input to the CPU 21, and further, the throttle opening and the engine speed are input.

The control method of the CPU 21 will be described with reference to the flowchart shown in FIG. When the ignition for starting the engine 11 is turned on, the CPU 21 starts the control in step 100 as shown in FIG. Next, at step 110, the throttle opening θ and the engine speed Ne are read. In step 120, step 100
Setting a target temperature T ₀ of the coolant on the basis of the throttle opening θ and the engine speed Ne read in. The setting of the target water temperature T ₀ may be calculated by a function f of θ and Ne, or a map of T ₀ (θ, Ne) may be prepared, and the target water temperature T ₀ may be calculated from this map by proportional calculation or the like.

In the next step 130, a duty ratio D which is an opening of the VSV 20 arranged between the intake manifold and the diaphragm chamber 197 is calculated. Calculating the duty ratio D may be calculated by the function g of the target temperature T _0, it is prepared a map in accordance with the target temperature T ₀ D (T _0),
The map D (T ₀ ) may be obtained by a proportional calculation or the like.

As the duty ratio D increases, the negative pressure of the intake manifold is directly transmitted to the diaphragm chamber 197, so that the negative pressure of the diaphragm chamber 197 increases. If the negative pressure in the diaphragm chamber 197 increases, the valve body 194 can be pulled up, so that the cooling water is guided to the second water conduit 18 and the water temperature rises. In step 140, the duty ratio D calculated in step 130 is output to the VSV 20, and the opening of the VSV 20 is controlled.

In the next step 150, the water temperature sensor 22
To detect the cooling water temperature T. In step 160,
The cooling water temperature T detected in step 150 and the target water temperature T ₀
At a predetermined temperature ΔT₁(T₀+ ΔT₁) And the ratio
Compare. The actual cooling water temperature T is equal to the temperature (T₀+ ΔT₁)Than
Is too high, the actual cooling water temperature T is equal to the target water temperature.
T₀Temperature ΔT₁The temperature is higher than
Target water temperature T₀Need to be corrected because it is not controlled
Judge that there is, and proceed to step 180 as “Yes”
I do.

At step 160, if the cooling water temperature T ₀ is lower than the temperature (T ₀ + ΔT ₁ ), it is determined to be “No” and the routine proceeds to step 170. In step 170, a coolant temperature T detected in step 150, the temperature from the target temperature T ₀ by subtracting a predetermined temperature [Delta] T ₂ (T ₀ -.DELTA.T
₂ ) and compare. The actual cooling water temperature T is equal to the temperature (T ₀ −Δ
When the temperature is higher than T ₂ ), it is determined that the cooling water temperature T is controlled to the target water temperature T ₀ and no correction is necessary, and the process returns to step 110.

Cooling water temperature T₀Is the temperature (T₀−ΔT_Two)Than
Is also low, the cooling water temperature T is equal to the target water temperature T.₀Yo
Specified temperature ΔT_TwoThe temperature is lower than
Warm T ₀Need to be corrected because it is not controlled
Judge, and proceed to step 190 as “Yes”.
In step 180, the cooling water temperature T is measured in step 160.
Water temperature T₀Is determined to be controlled to a higher temperature than
This is the step that moves when the Therefore, the cooling water temperature
In order to lower T, the du
Duty ratio D from the duty ratio D₁Pull
A new duty ratio D is calculated.

The duty calculated in step 130
A predetermined amount of duty ratio ΔD from ratio D ₁By pulling
When the duty ratio D is reduced, the opening of the VSV 20 is reduced.
And the negative pressure of the intake manifold transmitted to the diaphragm chamber 197
Becomes smaller. Manifold for the diaphragm chamber 197
The valve body 194 closes the communication hole 181 when the negative pressure of
Since it moves in the direction to open the communication hole 171,
Degree of cooling water hits the temperature sensitive part of thermostat 14,
The flow rate of the cooling water flowing into the diameter 15 is large.
And the temperature drops.

On the other hand, at step 170, it is determined that the cooling water temperature T is lower than the target water temperature T ₀ by a predetermined temperature ΔT ₂ or more. When the routine proceeds to step 190, the routine proceeds to step 130 to raise the cooling water temperature T. A predetermined amount of duty ratio ΔD ₂ is added to the calculated duty ratio to calculate a new duty ratio. If the duty ratio increases, the opening of the VSV 20 increases, so that the negative pressure of the intake manifold is transmitted into the diaphragm chamber 197. Then, the valve element 19
4 rises, and the cooling water flows into the second water conduit 18 so that the temperature of the cooling water is not transmitted to the thermostat 14. Therefore, as the duty ratio increases, the temperature of the cooling water increases.

Next, at step 200, the duty ratio D newly calculated at steps 180 and 190 is output to the VSV 20. Then, the process proceeds to step 110. The temperature is controlled by repeating the above flow chart. With such a system, it is possible to perform fine water temperature control according to the operating conditions at that time.

Further, information such as the nature and type of the fuel, for example, whether the fuel is regular or high-octane, or whether the fuel is methanol or light oil, is given to the CPU 21.
A function f for obtaining the target water temperature To or a map of To (θ, Ne) is deformed in the PU 21 depending on the property and type of the fuel, or a function or map separately stored in advance for each fuel is used. By reading the information, the water temperature can be controlled according to the properties and types of the fuel. As means for giving information on the property and type of fuel to the CPU 21, a sensor may be used, or a driver may give an instruction using a changeover switch or the like.

Further, if the configuration shown in FIG. 9 to which a knock signal is added is used as an input signal of the CPU 21 shown in FIG. 2, finer water temperature control can be performed depending on whether knock has occurred. That is, it is possible to realize optimal water temperature control not only in accordance with the operating conditions of the engine 11 but also in changing environmental conditions such as atmospheric pressure and atmospheric temperature. Alternatively, this is an effective control method even in the case of supercharging as in a turbocharged engine.

Next, a control method of the CPU 21 in the configuration of FIG. 9 will be described based on a flowchart shown in FIG. Steps 100 to 200 are controlled in the same manner as in FIG. In step 210, when the knock signal is "present", it is considered that knock has occurred because the suction pressure is high or the suction temperature is high, and it is determined that knock should be suppressed by lowering the water temperature, At step 220,
By subtracting a predetermined amount of the duty ratio ΔD ₃ , a new duty ratio is calculated. Then, at step 230, the VSV
20 and return to step 110. If the knock signal is “absent” in step 210, step 11
Return to 0. If NO is determined in step 170, the process proceeds to step 210 to determine the presence or absence of a knock signal.

In particular, when it is determined that the water temperature becomes too high and it is dangerous, the VSV 20 may be used to cut the negative pressure of the intake manifold. If the negative pressure of the intake manifold is cut, the force by which the spring 192 pushes down the diaphragm 193 becomes stronger, and the valve body 194 descends so that the cooling water flows through the first water conduit 17. In this way, since the high-temperature cooling water flows toward the temperature sensing portion of the thermostat 14, the thermostat 14 is stabilized on the valve-opening side, and the flow rate of the cooling water exchanged by the radiator 15 increases. Dangerous states such as overheating can be prevented beforehand as the water temperature drops.

In this embodiment, the negative pressure of the intake manifold is applied to the diaphragm chamber 197. However, the present invention is not limited to this, and is connected to a vacuum tank capable of applying a predetermined amount of negative pressure, and the throttle opening and the engine are controlled. The load state of the engine may be detected only by the rotation speed. Next, other examples of the structure of the flow control valve 19 are shown in FIGS.

In the flow control valve 23 shown in FIG. 3, diaphragms 24 and 25 as actuators are joined to both ends of a shaft 26, and a valve body 27 is provided in the middle of the shaft 26. The illustrated upper space 241 of the diaphragm 24 is connected to an intake manifold, and a negative pressure of the intake manifold acts on the diaphragm 24. In this upper space 241, a spring 242 for pressing the diaphragm 24 downward in the drawing is arranged. Also, the diaphragm 25
The illustrated lower space 251 is open to the atmosphere.

At a low load, a large suction force acts on the diaphragm 24 because the negative pressure of the intake manifold is large. When the suction force due to the negative pressure is greater than the pressing force of the spring 242, the valve body 27 is pulled up together with the diaphragm 24. As a result, most of the cooling water flowing from the bypass passage 13 enters the chamber 30 through the communication hole 28, flows into the second water passage 18, flows into the engine 11 without passing through the thermostat 14, and raises the water temperature. Let it.

Conversely, when the load is high, the valve body 27 moves in a direction to close the communication hole 28 because the negative pressure of the intake manifold is small, and most of the cooling water flowing from the bypass passage 13 passes through the communication hole 29. After entering the chamber 31 and flowing to the first water channel 17, high-temperature cooling water is applied to the thermostat 14, and the thermostat 14 increases the flow rate through the radiator 15 to lower the water temperature.

By the way, a part of the cooling water flowing from the bypass passage 13 is squeezed through the passages 32 and 33.
And flows in, and the diaphragm adjacent chamber 34,
35, and through the gaps 36 and 37, the first headrace 17
, And the water pressure in the diaphragm adjacent chambers 34 and 35 is always the same, and the diaphragm 2
4 is canceled by the pushing-down force of the water pressure applied to the diaphragm 25, and the valve body 2 is actuated by the diaphragm actuator only by the negative pressure of the intake manifold.
7 can be controlled.

FIG. 14 shows a modification of the flow control valve 23 shown in FIG. The same components as those of the flow control valve 23 in FIG. In the flow control valve 61 shown in FIG. 14, 62 and 63 are water pressure reduction ports. The water pressure reducing ports 62 and 63 correspond to the squeezing passages 32 and 33 and the clearances 36 and 37 in the flow control valve 23 in FIG.
More cooling water flows in. In the flow control valve 23 of FIG. 3, the cooling water flowing into the diaphragm adjacent chambers 34, 35 flows out through the gaps 36, 37 to the first water passage 17 and the second water passage 18, but in this embodiment. The flow control valve 61 of
The clearances 36 and 37 are set to the minimum necessary size, and the water pressure reduction ports 62 and 63 that connect the first water passage 17 and the second water passage 18 to the water passage 18 from the side walls of the diaphragm adjacent chambers 34 and 35.
Is provided. In the flow regulating valve 23 shown in FIG.
Since the clearances 36 and 37 are provided around the periphery of the shaft 6, the shaft 26 may be wobble, making it impossible to completely seal the valve body 27. However, this embodiment does not have such a problem. In addition, 621 and 631 are squeezes.

FIG. 15 shows the flow control valve 2 shown in FIGS.
3, 61, clearances 36, 37 are minimized
And corresponding to the water pressure reduction ports 62 and 63
FIG. With the configuration shown in FIG.
Are going forward like the dashed lines a and b in FIG.
On the way back, it has some hysteresis,
The size of the lysis increases as the engine speed increases.
It will be good. For example, when the intake manifold negative pressure is sufficiently large, FIG.
As shown in 5, the valve is pulled to the full right position
The entire amount of water from the outlet to the inlet pipe
Is controlled to flow to At this time, the water pressure P₁And water pressure P
_ThreeAre almost equal, but the water pressure P_TwoIs the flow of water
Water pressure P₁The pressure is lower than that of. others
The area of the valve body 27 is S_BAs (P
₁−P_Two) × S_BValve pressing force works. And the water pressure P
₁And water pressure P_TwoIs actually measured as shown in FIG.
The higher the number, the higher (P₁−P_Two) Increases in proportion to the rotation speed.
Therefore, the pressing force of the valve body 27 also increases in proportion to the rotation speed.
It becomes.

When the intake manifold negative pressure is lowered from the state shown in FIG. 15, it moves on a line shifted to the left from the line c as shown by the line b in FIG. It increases in proportion. The line c is a line when it is assumed that there is no valve body pressing force, and is a line having no hysteresis between going and returning. On the other hand, when the intake manifold negative pressure is sufficiently small and the valve body 27 is at the full left position, the hydraulic pressure P ₁ and the hydraulic pressure P ₂ are substantially equal to each other, but the hydraulic pressure P ₃ is smaller than the hydraulic pressure P _1. Lower, so (P
₁ -P ₃₎ valve body pressing force of × S _B works, from this state when went up the intake manifold negative pressure, motion line on which is offset to the right from the c line as a line in FIG. 16, the The magnitude of the deviation increases in proportion to the rotation speed.

However, in the flow control valves 23 and 61 shown in FIGS. 3 and 14 described above, the clearances 36 and 3 are provided.
7 and the water pressure reduction ports 62 and 63, the valve body pressing force can be canceled. For the sake of explanation, first, as shown in FIG. 18, a case where a water pressure reducing port 62 is provided only in one diaphragm chamber 35 will be described. FIG. 18 is for canceling the valve body pressing force when the valve body is in the state shown in FIG. 15, and the line b in FIG. 16 can be made to coincide with the line c regardless of the number of rotations. That is, the diaphragm adjacent room 3
5 is provided with a water pressure reduction port 62 so that the water pressure P ₁
A minute flow rate q of the root is proportional to the difference between the pressure P ₂ (P ₁ -P ₂₎ flows in the diaphragm adjacent room 35. Then, the pressure in the diaphragm adjacent chamber 35 is changed to the pressure in the diaphragm adjacent chamber 34.
Compared to the pressure of the inner, reduced by [Delta] P, and the area of the diaphragm and S _D, the valve body return force represented by [Delta] P × S _D is, the valve body pressing force of the aforementioned (P ₁ -P ₂₎ and × S _B Work in the opposite direction. The pressure drop ΔP is proportional to the square of the minute flow rate q,
q is d ² × √ (P ₁ −P ₂ ), where squeezing diameter is φd.
, And (P ₁ −P ₂ ) is proportional to the rotation speed Ne, so ΔP∝Ne. As a result, the valve body pressing force (P ₁ −
The magnitudes of P ₂ ) × S _B and the valve body return force ΔP × S _D are proportional to each other. Therefore, by selecting the throttle diameter φd so that the magnitude of the valve element pressing force and the magnitude of the valve element returning force are equalized, the valve element pressing force can be canceled, and the line b in FIG. Regardless of the number of rotations,
Can be matched.

Of course, the present method not only makes the b-line coincide with the c-line, but also provides a means for moving the b-line in FIG. 16 to the right. The amount can be set freely. For example, it is also possible to move the b-line further to the right side than the c-line, and to set the valve to move at a high rotation speed when the intake manifold negative pressure is greater than the c-line.

On the other hand, the line a in FIG.
In order to reduce the water pressure, a similar
If a port is provided, the line a
The amount of movement to the left can be set freely.
You. FIG. 14A shows the state when the intake manifold negative pressure is sufficiently small.
And the valve body 27 is in a position where the valve body 27 is fully left-handed.
You. Main water flow from outlet to thermostat
As it flows, water pressure P₁And water pressure P_TwoAre approximately equal,
Water hardly flows in the water pressure reduction port 62. others
Therefore, the water pressure in the diaphragm adjacent chamber 35 is equal to the water pressure P₁Close to
Value. However, the inside of the water pressure reducing port 63 is d_A ^Two
√ (P₁−P _Three) Small flow rate q_ADoes it flow
The water pressure in the diaphragm adjacent chamber 34 is
ΔP compared to the water pressure in the chamber 35_AAnd ΔP_A× S_D
The valve return force acts to the right, and the valve pressing force (P₁−
P_Three) × S_BLine a in FIG. 16 to the left
Can be moved.

Similarly, when the intake manifold negative pressure is sufficiently large and the valve body 27 is at the position shown in FIG.
Contrary to the In the case of (A), the water pressure reduction port 63 water does not flow, the water pressure reducing port in ^{_{62 d B 2 √ (P 1}} -P 2)
Since flows proportional to minute flow rate q _B, the water pressure in the diaphragm adjacent room 35 as compared to water pressure in the diaphragm adjacent chamber 34, decreases by [Delta] P _B, the valve body return force ΔP _B × S _D acts to the left, because against the valve body pressing force _{(P 1 -P 2) × S} B, it is possible to move the b line in Fig. 16 to the right.

[0045] Thus, by the choice of aperture diameter .phi.d _A or .phi.d _B, can be configured in exactly the c line no hysteresis characteristics of FIG. 16, of course, set at an arbitrary characteristic having hysteresis as needed You can also. FIG. 11 shows another example of the flow control valve. The flow regulating valve 53 in FIG. 11 is pressed against the shaft 55 of the butterfly valve 54 at the position shown in FIG. Only flow to waterway 18 is allowed. A lever 57 is provided on the shaft 55, and a wire 58 is connected to an accelerator pedal 60 via a pulley 59.

The flow control valve 53 is connected to the accelerator pedal 6
0 is depressed and the load increases, the wire 5
8, the butterfly valve 54 rotates clockwise, and the cooling water also starts flowing to the first water conduit 17. And, the more the accelerator pedal 60 is depressed, the more depressed, that is,
As the load increases, the amount of water flowing to the first headrace 17 increases, and accordingly, the amount of water flowing to the second headrace 18 decreases, and finally the water flows only to the first headrace 17. be able to. In other words, the flow ratio between the first headrace 17 and the second headrace 18 can be changed according to the load, and the water temperature is increased at a low load, and is decreased at a high load. Can be.

Next, a third embodiment of the present invention will be described with reference to FIG. The present embodiment is an apparatus including a method for accelerating a rise in water temperature when the engine is warmed up. The engine shown in FIG. 4 is an intake-side advanced cooling type engine 40 having an intake-side advanced cooling passage 41. The intake side pre-cooling means that low-temperature cooling water from the outlet of the radiator 15 is first supplied to the engine 4.
The cooling water is passed through a cooling water passage (preceding cooling passage) 41 on the intake port side of the cylinder head inside the cylinder 0, and then the pressure is increased by the pump 16 to flow through the cooling water passage on the exhaust port side of the cylinder block or cylinder head. . Accordingly, since the low-temperature cooling water flowing out of the radiator 15 always flows to the intake port side, the intake port can be always kept at a low temperature, and particularly, the output at the time of high load after the warm-up is completed can be increased. it can.

On the other hand, during warm-up, the main valve 141 of the thermostat 14 is closed, and the cooling water from the radiator 15 does not enter the engine 40. At this time, the bypass valve 1
Reference numeral 42 indicates that the engine 4 is in the fully opened state, contrary to the main valve 141, and the engine 4
The cooling water in the engine 4 is returned to the pump 16 from the internal bypass passage 42 through the preceding cooling passage 41,
It is configured to circulate only within 0 and hasten the rise of the water temperature.

In this embodiment, a switching valve 43 is used as shown in FIG. 4 in order to further increase the water temperature. The switching valve 43 has the same structure as the flow regulating valve 19.
The internal bypass passage 42 has a diameter for securing a required amount as an internal circulation amount at the time of warm-up. The diameter of the internal bypass passage 42 of the engine 40 used in the experiment by the present inventor is φ
13 [mm]. This diameter is made smaller or completely eliminated, and a bypass flow path 44 having a diameter corresponding to the reduced cross-sectional area of the internal bypass flow path 42 is provided.

Although the bypass passage 44 is taken out from the cooling water passage 12 in FIG. 4, it may be basically provided from any position on the discharge side of the pump 16. A switching valve 43 is provided in the middle of the bypass flow path 44, and the diaphragm chamber 437 is piped through the VSV 20 so that a negative pressure of the intake manifold acts on the diaphragm chamber 437. The water temperature detected by the water temperature sensor 46 disposed on the side is determined, and when the temperature is lower than the predetermined temperature, the VSV 20 is operated to connect the intake manifold to the diaphragm chamber 437 of the switching valve 43.

As a result, the negative pressure of the intake manifold acts on the diaphragm 431 to pull up the valve body 434, and the cooling water from the bypass flow passage 44 passes through the bypass flow passage 45 and the pump 1
6 and is sucked by the pump 16. In this configuration, the flow of the cooling water in the preceding cooling passage 41 is such that the diameter of the internal bypass passage 42 is reduced,
Or, it is stagnant because it is completely lost.

As a result, the wall temperature on the intake port side rises, so that the intake air taken into the engine 40 is heated and the intake air temperature rises. When the intake air temperature rises, the heat loss Qw of cooling of the engine 40 increases, so that the rise in water temperature can be accelerated. FIG. 5 experimentally confirms the increase in the water temperature. The switching valve 43 of FIG.
A conventional cooling device having no flow control valve 19 and bypass flow paths 44, 45, and 13, and a first water passage 17 and a second water passage 18, and a diameter of an internal bypass flow passage 42 of φ13 [mm]. The cooling water is returned from the bypass passage 44 to the inlet of the pump 16 through the bypass passage 45 by raising the valve body 434 of the switching valve 43 of FIG.
This is a comparison with the example of the present invention in which 6.5 [mm] is set. The operating condition is a first idle operation immediately after starting the engine from room temperature. As shown in the experimental results, the rotation speed is high immediately after the start of the engine 40, but gradually decreases as the water temperature increases.

In the apparatus of the present invention, the intake air temperature rises faster than in the conventional apparatus, and the water temperature (pump inlet water temperature) is increased as described above.
Was able to hasten the rise. As a result, the decrease in the engine speed could be accelerated. FIG. 6 shows the emission characteristics when the experiment was performed under the same conditions. The time required to shift to the feedback state in which the air-fuel ratio A / F is controlled to 14.5 is shortened by about 20 seconds as compared with the related art. CO and THC emissions could be reduced.

Before entering the feedback state, the air-fuel ratio A / F is set to the rich side. However, the period in this state is shortened, and the engine speed is also reduced from the current state as shown in FIG. Because it can be lowered, fuel consumption during warm-up also decreases. In the apparatus shown in FIG. 4, the negative pressure of the intake manifold is applied to the diaphragm chamber 437 during warm-up so that
4 is controlled, but the throttle is depressed,
That is, when the load is high, the negative pressure of the intake manifold may be small and the valve body 434 may not be pulled up.
However, in such a high load state, the warm-up is early from the beginning, and the state in which the valve body 434 is lowered does not matter.

Further, as another embodiment, if the switching valve 43 is replaced by an electrically operable valve such as an electromagnetic valve or a valve operated by using engine oil pressure, the valve body 434 is always raised when the water temperature is low. It is possible to do so. Further, when the warm-up is completed and the water temperature exceeds a predetermined temperature, the VSV 20 is operated by the CPU 21 to make the diaphragm chamber 437 conductive to the atmosphere. As a result, the valve body 434 descends, and the cooling water enters the flow control valve 19 through the bypass passage 13. The flow control valve 19 is the first flow control valve shown in FIG.
This is the same as the embodiment, and changes the distribution of the cooling water to the first water conduit 17 and the second water conduit 18 according to the negative pressure of the intake manifold.

Therefore, after the warm-up is completed, the same water temperature control as in the first embodiment can be performed. Further, the switching valve 43 and the flow regulating valve 19 in FIG. 4 may be structured as shown in FIG. An embodiment of a danger avoidance method when the water temperature becomes too high will be described with reference to FIG. The same components as those in the second embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The fourth embodiment shown in FIG. 8 is similar to the second embodiment shown in FIG.
In the embodiment, the flow path adjustment valve 23 shown in FIG. 3 is used instead of the flow path adjustment valve 19, and a TVSV (thermostatic sensor) is used instead of the VSV 20, the CPU 21, and the water temperature sensor 22.
This is an example using a vacuum switching valve (50). The present embodiment is an example in which the engine 40 of the intake side pre-cooling system is used as the engine. TVSV50,
The temperature sensing portion 501 is provided to protrude into the preceding cooling passage 41, detects the temperature of the cooling water flowing through the preceding cooling passage 41, and switches the valve according to the temperature detected by the temperature sensing portion 501. . Further, the TVSV 50 is supplied with a negative pressure of the intake manifold and the atmosphere.

If the temperature of the cooling water detected by the temperature sensing section 501 of the TVSV 50 is lower than a predetermined temperature, the upper space 24
1, the negative pressure of the intake manifold is applied, and the atmospheric pressure is applied to the lower space 251. On the other hand, the temperature sensing part 50 of the TVSV 50
When the temperature of the cooling water detected in step 1 is higher than a predetermined temperature, atmospheric pressure is applied to the upper space 241 and the lower space 251
Is configured to apply a negative pressure to the intake manifold. When the temperature of the cooling water is equal to or lower than the predetermined temperature, the negative pressure of the intake manifold is applied to the upper space 241 and the atmospheric pressure is applied to the lower space 251. Therefore, the diaphragm 24 is controlled by the negative pressure of the intake manifold, and the cooling water flows. First headrace 17 and second headrace 18
And the cooling water temperature is controlled to an appropriate temperature.

On the other hand, when the temperature of the cooling water is equal to or higher than the predetermined temperature, negative pressure of the intake manifold is applied to the lower space 251 and atmospheric pressure is applied to the upper space 241.
The valve body 27 is pushed leftward in FIG. 25 by the force of the spring 242 pushing leftward in the figure and the force of the negative pressure of the intake manifold in the lower space 251 pulling the diaphragm leftward in the figure. The communication hole 28 is closed by the valve body 27, and the cooling water flows through the communication hole 29 into the first water conduit 17. The cooling water flowing into the first water channel 17 directly hits the temperature sensing part 143 of the thermostat 14. Then, the temperature sensing part 143 of the thermostat 14 detects that the cooling water is at a temperature higher than the predetermined temperature, opens the main valve 141 of the thermostat 14 greatly, and supplies the cooling water to the radiator 15 via the engine 40. Into the tank. Therefore, since the cooling water is cooled by the radiator 15, the cooling water temperature can be reduced.

In this embodiment, the temperature-sensitive part 501 of the TVSV 50 is arranged in the cooling water in the pre-cooling passage 41 by using the engine 40 of the pre-cooling system on the intake side.
Not only the intake side pre-cooling type engine 40 but also the first
The engine used in the embodiment and the second embodiment may be used. In the present embodiment, the temperature of the cooling water flowing in the intake-side preceding cooling passage 41 is detected. However, the present invention is not limited to this.
The measurement may be performed in any of the cooling water channel systems including the cooling water channel 12, the bypass channel 13, the first water channel 17, and the second water channel 18.

Also, instead of TVSV50, BVSV
(Bimetal vacuum switching valve), and the bimetal portion of the BVSV may be provided in the cooling water channel system. According to the BVSV, the bimetal portion detects the cooling water temperature, and can switch between the negative pressure of the intake manifold and the atmospheric pressure as in the TVSV 50. Next, a fifth embodiment for performing water temperature control using a knock control system (KCS) will be described with reference to FIGS.

FIG. 12 shows a configuration diagram of this embodiment. Although the configuration is almost the same as that of the embodiment shown in FIG. 9, the control logic of the KCS is included in the CPU 21. The CPU 21 receives the knock signal, performs the calculation inside the CPU 21, and sets the ignition timing of the engine to the trace knock point. 9 is different from the embodiment shown in FIG. here,
The function of the KCS will be described. The KCS is a system that controls the ignition timing so as to be at a trace knock point (near a knock limit, a minute knocking state, or a state immediately before knocking occurs) regardless of the operating conditions of the engine.

However, only the ignition timing is controlled to the trace knock point, and the trace knock point is not always optimal for the fuel efficiency and output of the engine.
The optimal ignition timing for engine fuel efficiency and output is
MBT (Minimum Spark Advance)
for Best Torrue, ignition timing immediately before reaching a flat shaft torque). When the engine is in a high load state, knocking usually occurs on the retard side from the MBT, so that the engine must be operated at a trace knock point on the retard side from the MBT. Therefore, if the water temperature is controlled so that the trace knock point approaches MBT as much as possible, it is possible to improve the fuel efficiency and output of the engine. This control is performed by the system shown in FIG.

The control method of the CPU 21 in this system will be described with reference to the flowchart of FIG. Step 1
When the control is started at 00, the throttle opening θ and the engine speed N are set as engine conditions at step 110.
Read e. Next, in step 115, it is determined whether or not the currently read engine condition has changed from the previously read engine condition. If Yes, the process proceeds to step 125, where the target water temperature To and the target ignition timing θigo are set.
The target ignition timing θigo may be set so as to coincide with the MBT described above, or may be set on a retard side of the MBT and close to the MBT in consideration of safety.

Thereafter, at step 130, the duty ratio D is calculated according to the target water temperature To, and at the next step 140
Output the duty ratio D to the VSV 20. In the next step 150, the coolant temperature T is detected by the coolant temperature sensor 22. On the other hand, if it is determined in step 115 that the engine conditions have not changed from the previous
Move to 50.

Steps 150 to 200 are exactly the same as those in FIG. 10, and a description thereof will be omitted. However, if NO is determined in step 170, it is determined that the water temperature T is controlled to be near the target water temperature To, and the process proceeds to step 210. After outputting the duty ratio D in step 200, the process returns to step 110.

In step 210, the actual ignition timing θig is detected by using a means such as reading out the ignition timing output by calculation inside the KCS. Step 22
0, the difference from the target ignition timing θigo (θigo−θi)
The target water temperature To is changed according to g). Here, assuming that the ignition timing θig and the target ignition timing θigo are advance amounts with reference to TDC, if the difference (θigo-θig) is positive, the actual ignition timing θig is retarded from the target ignition timing θigo. Therefore, it is determined that knocking is likely to occur, and the target water temperature To is lowered. Conversely, if the difference (θigo−θig) is negative, it is determined that the advance is excessive, and the target water temperature To is raised. Difference (θigo-θi
If g) is 0, the target temperature T
o does not change.

As an arithmetic expression for realizing the above contents, for example, there is the following expression.

[0069]

## EQU1 ## where To = To-K (.theta.igo-.theta.ig) where K is a constant. In addition, the difference (θigo
−θig) is set to Δθig, and the change amount ΔTo of the target water temperature To may be obtained by the function or the map k as in the following Expression 2, and further, the target water temperature To may be obtained by using the following Expression 3.

[0070]

## EQU2 ## ΔTo = k (Δθig)

[0071]

## EQU3 ## As long as the above contents can be realized, the calculation method does not matter. Then, at step 230, the new target water temperature To
Is calculated in step 240, and the process returns to step 110.

It should be noted that step 115 in FIG. 13 is inserted between steps 110 and 120 in FIGS. 7 and 10, and if yes, the procedure goes to step 120; May be the same as Next, regarding a sixth embodiment of the present invention,
This will be described with reference to FIG. Note that the same reference numerals are given to the same components in the above-described embodiment, and detailed description thereof will be omitted. The overall configuration is the same as that of the fourth embodiment in FIG. 8, and a TVSV (thermostatic vacuum switching valve) 5 in the fourth embodiment.
The negative pressure of the intake manifold is directly connected to the flow control valve 23 instead of 0, and the valve body 2
7 is operated. In the intake pipe passage 300, an air cleaner 310 is provided near the intake port, and a throttle valve 330 is provided near the front of the intake manifold.

Further, in the intake pipe passage 300, an interwarmer 320 is provided between the air cleaner 310 and the throttle valve 330, through which the second water conduit 18 is guided. The interwarmer 320 has a heater core 321 formed therein, and the second
The headrace 18 is then bypassed to the inlet of the pump 16.

With the above configuration, when the engine 40 is operated at a low load, the negative pressure of the intake manifold is large, so that the valve body 27 is moved by the negative pressure of the intake manifold guided to the flow control valve 23 in the figure. , And moves rightward to close the communication between the bypass passage 13 and the first headrace 17 and conversely connects the bypass passage 13 and the second headrace 18. Therefore, the cooling water in the bypass passage 13 enters the interwarmer 320 through the second water conduit 18, heats the intake air by the heater core 321, and then flows into the inlet of the pump 16.

On the intake port side of the engine 40,
A preceding cooling water passage 41 is provided, and the flow regulating valve 23 is provided.
As a result, the flow of the cooling water into the first water passage 17 is prevented, so that the flow velocity in the preceding cooling water passage 41 is reduced, the wall temperature on the intake manifold side is increased, and the intake air is thereby heated at the same time. become. Thus, the intake air temperature at a low load is greatly increased, and the fuel consumption is further reduced.

When the load is high, the negative pressure of the intake manifold decreases and the valve body 27 moves to the left in the figure, and the high-temperature cooling water that has passed through the bypass passage 13 flows into the first water conduit 17. The thermostat 14 is guided near the temperature sensing portion of the thermostat 14, so that the thermostat 14 is stabilized on the valve opening side, and the cooling water flowing through the radiator 15 has a large amount.
0, the water temperature in the engine 40 is lowered, and the flow of the cooling water into the interwarmer 320 is stopped. Therefore, the heating of the intake air temperature is stopped, and the intake of the engine is performed at a high temperature. In the configuration of the sixth embodiment, during a low-load warm-up operation, the cooling loss Qw due to an increase in the intake air temperature can be increased, so that the water temperature rise can be drastically accelerated, and the fuel efficiency during warm-up can be improved. Can also be significantly improved. Further, in the above embodiment, the interwarmer 320 is provided in the intake pipe passage between the throttle valve 330 and the air cleaner 310. However, as long as the intake air can be heated, the present invention is not limited to this location. It may be provided at the place. Also, it goes without saying that the configuration of the interwarmer 320 is not limited to the above configuration as long as the same action is produced. Further, each configuration described in the first to fifth embodiments can be applied as appropriate.

In the above embodiment, the state where the valve body 27 is completely moved to either one and the passage is closed has been described. However, the valve body 27 is continuously moved in the axial direction according to the negative pressure. It is possible to continuously control the amount of cooling water to the first water conduit 17 and the second water conduit 18 to form an optimal flow rate balance to each passage, thereby achieving higher precision. Temperature control can be realized.

FIG. 20 shows a seventh embodiment as another embodiment for heating the intake air. In FIG. 20, in addition to the configuration of the sixth embodiment, the intake air pipe passage 300 further includes an intake bypass passage 3 for bypassing intake air.
40, and an interwarmer 320 is provided in the intake bypass passage 340. further,
Each passage is provided with a switching valve 360 for switching the intake air guided from the air cleaner 310 to only one of the passages. The switching valve 360 is connected to the diaphragm actuator 350 by a link mechanism or the like, and is driven by the diaphragm actuator 350. An opening / closing switching operation of the intake pipe passage is performed. Further, a negative pressure of the intake manifold is guided to the diaphragm type actuator 350, and the diaphragm type actuator 350 is driven by the negative pressure.

Therefore, when the load is low, the negative pressure of the intake manifold is large and the diaphragm actuator 3
The switching valve 360 connected by a link mechanism or the like is driven to suck the 50 diaphragm 350a, thereby closing the intake pipe passage 300 and opening the intake bypass passage 340. Therefore, the intake air guided to intake bypass passage 340 is supplied to inter warmer 32.
It is heated at 0 and supplied to the engine. On the other hand, when the load is high, the negative pressure of the intake manifold is small, and the suction force of the diaphragm 350a is reduced, so that the spring 350
As a result of the diaphragm 350a being pushed back by b, the switching valve 360 linked thereto is operated to open the intake pipe passage 300 and close the intake bypass passage 340. Therefore, when the load is high, the intake air at the high temperature from the air cleaner 310 is immediately supplied and is taken into the engine 40.

With the above-described configuration, the intake air temperature is switched immediately according to the load, and the intake air temperature control excellent in response can be performed.

[0081]

As described above, according to the cooling system for an internal combustion engine of the present invention, the cooling water flowing into the internal combustion engine when the load is low is maintained without changing the amount of water passing through the internal combustion engine. It is possible to obtain an excellent effect that the temperature can be increased and the temperature of the cooling water flowing into the internal combustion engine can be decreased when the load is high. In addition, by guiding the bypassed cooling water to the intake pipe passage, the intake air is heated, so that it is possible to reduce fuel consumption at a low load.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a cooling device for an internal combustion engine of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of a cooling device for an internal combustion engine of the present invention.

FIG. 3 is a sectional view of a main part showing another embodiment of the flow regulating valve.

FIG. 4 is a configuration diagram showing a third embodiment of a cooling device for an internal combustion engine of the present invention.

FIG. 5 is a diagram showing experimental results in a third embodiment of the present invention.

FIG. 6 is a diagram showing experimental results in a third embodiment of the present invention.

FIG. 7 is a flowchart illustrating control of a control unit according to a second embodiment of the present invention.

FIG. 8 is a configuration diagram showing a fourth embodiment of a cooling device for an internal combustion engine of the present invention.

FIG. 9 is a configuration diagram showing another embodiment of the present invention.

FIG. 10 is a flowchart showing control of a control unit in the embodiment shown in FIG.

FIG. 11 is a view showing another embodiment of the flow regulating valve.

FIG. 12 is a configuration diagram showing a fifth embodiment of the present invention.

FIG. 13 is a flowchart illustrating control of a control unit according to a fifth embodiment of the present invention.

FIGS. 14A and 14B are cross-sectional views of a main part showing another embodiment of the flow control valve.

FIG. 15 is a view showing a flow regulating valve.

FIG. 16 is a diagram showing a relationship between an intake manifold negative pressure and a valve position.

FIG. 17 is a diagram showing a relationship between engine speed and water pressure.

FIG. 18 is a view showing a flow control valve.

FIG. 19 is a configuration diagram showing a sixth embodiment of a cooling device for an internal combustion engine of the present invention.

FIG. 20 is a configuration diagram showing a seventh embodiment of a cooling device for an internal combustion engine of the present invention.

DESCRIPTION OF SYMBOLS 10 Cooling device 11 Internal combustion engine 12 Cooling channel 13 Bypass channel (first bypass channel) 14 Thermostat (Flow control valve) 15 Radiator (Heat exchanger) 16 Pump 17 First water channel (First) 18) Second water conduit (second bypass channel) 19 Flow control valve 20 VSV 21 CPU 22 Water temperature sensor 43 Switching valve 44 Bypass channel 45 Bypass channel 50 TVSV

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Fukunaga 14 Iwatani, Shimowakaku-cho, Nishio-shi, Aichi Prefecture Inside the Japan Automobile Parts Research Institute (72) Inventor Yasutoshi Yamanaka 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Nippon Denso Incorporated (56) References JP-A 61-160224 (JP, U) JP-A 1-124330 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F01P 7/16 502 F01P 7/16 503

Claims (5)

(57) [Claims] 1. A heat exchanger for cooling cooling water of an internal combustion engine, and cooling water flowing out of the internal combustion engine is led to the heat exchanger, and the cooling water cooled by the heat exchanger is supplied to the internal combustion engine. A cooling water channel to be introduced into the cooling water channel, which is disposed in parallel with the cooling water channel, and in which cooling water flowing out of the internal combustion engine flows in, bypasses the heat exchanger, and flows into the cooling water channel on the downstream side of the heat exchanger. A first bypass flow path to be discharged, and a position where the first bypass flow path is connected to the cooling water passage on the downstream side of the heat exchanger, and detects a cooling water temperature to reduce the cooling water temperature. A flow control valve that adjusts a ratio of a flow rate of each of the cooling water path and the bypass flow path, a cooling water circulation pump provided in the cooling water path, and a load state of the internal combustion engine. Load state detecting means; and the first bypasser A second bypass passage through which cooling water flows in the middle of the cooling water passage, and flows out to the cooling water passage between the flow control valve and the internal combustion engine, and in the middle of the first bypass passage, The second bypass flow path is disposed at a position where the second bypass flow path is connected, and when the state of the internal combustion engine detected by the load state detection means is a low load state lower than a predetermined load, When more cooling water flows into the path than the first bypass flow path, and the state of the internal combustion engine detected by the load state detecting means is a high load state equal to or higher than a predetermined load,
A cooling device for an internal combustion engine, comprising: a flow control valve that allows more cooling water to flow into the first bypass flow path than the second bypass flow path. 2. The load state detecting means detects a negative pressure in an intake pipe for supplying an air-fuel mixture to the internal combustion engine, and the flow control valve adjusts a flow distribution according to the negative pressure. The cooling device for an internal combustion engine according to claim 1. 3. The internal combustion engine is a water-cooled internal combustion engine having an intake-side preceding cooling passage, and a third connecting a discharge side of cooling water of the internal combustion engine and a downstream side of the intake-side preceding cooling passage. 3. The cooling device for an internal combustion engine according to claim 1, wherein a bypass flow path is provided, and when the cooling water is warmed up at a predetermined temperature or lower, the cooling water flows into the bypass flow path. 4. A water temperature detecting means for detecting a temperature of the cooling water, wherein when the temperature detected by the water temperature detecting means is equal to or higher than a predetermined temperature, the flow regulating valve is connected to the first bypass flow path. 4. The cooling device for an internal combustion engine according to claim 1, wherein more cooling water flows into the second bypass flow path. 5. 5. The cooling device for an internal combustion engine according to claim 1, wherein the second bypass flow path passes through intake air heating means provided in an intake pipe of the internal combustion engine.