WO2011148464A1

WO2011148464A1 - Cooling device for internal combustion engine

Info

Publication number: WO2011148464A1
Application number: PCT/JP2010/058833
Authority: WO
Inventors: 夕加里荒木; 信峯竹内
Original assignee: トヨタ自動車株式会社
Priority date: 2010-05-25
Filing date: 2010-05-25
Publication date: 2011-12-01

Abstract

A cooling device for an internal combustion engine, configured so that coolant circulation is stopped until the temperature of the coolant reaches a predetermined temperature, wherein thermal shock to the internal combustion engine, which is likely to occur when the stop of the coolant circulation is cancelled, is reduced. An internal combustion engine (10) is provided with: a main passage (24) and a sub-passage (27) which form the engine cooling system; a coolant temperature sensor (92) which detects a first temperature which is the temperature of the coolant within the internal combustion engine (10); and an electric pump (23). A control device (91) controls the electric pump (23) so that the coolant circulation is stopped when the first temperature is lower than a predetermined temperature. Also, the control device (91) sets the discharge amount of the coolant which is discharged from the electric pump (23) when the stop of the coolant circulation is cancelled, the setting being performed on the basis of the temperature of the coolant within the sub-passage (27) when the coolant circulation is being stopped.

Description

Cooling device for internal combustion engine

The present invention relates to a cooling device for an internal combustion engine in which the circulation of the cooling water is stopped until the temperature of the cooling water reaches a predetermined temperature in order to promote warm-up of the internal combustion engine.

As a cooling device for an internal combustion engine, a water-cooling type cooling device that cools a cylinder block or a cylinder head by circulating cooling water through a water jacket formed inside the internal combustion engine is generally known. Normally, the engine cooling system of such a cooling device is constituted by a water jacket, a pump, a radiator, a cooling water passage that communicates the water jacket with the radiator, and a thermostat that regulates the flow rate of the cooling water flowing into the radiator.

By the way, in recent years, as a pump for circulating the cooling water, a pump capable of changing the discharge amount of the cooling water without depending on the engine operation state, for example, an electric pump has been put into practical use.

For example, the cooling device described in Patent Document 1 employs such an electric pump and stops the operation of the electric pump and stops the circulation of the cooling water until the temperature of the cooling water reaches a predetermined temperature at the time of starting the engine or the like. I am doing so.

When the circulation of the cooling water is stopped while the engine is operating as in such a cooling device, the cooling water in the internal combustion engine is stagnated in the internal combustion engine. Therefore, the temperature of the cooling water in the internal combustion engine is quickly raised by engine heat. Therefore, warming up of the internal combustion engine is promoted.

JP 2002-161748 A

By the way, in the cooling device described above, when the temperature of the cooling water reaches a predetermined temperature, the operation of the electric pump is started and the circulation of the cooling water is started. When the circulation of the cooling water is started in this way, the cooling water existing outside the internal combustion engine in the engine cooling system, for example, the cooling water stagnating in the cooling water passage communicating the water jacket and the radiator. Etc. will flow into the internal combustion engine.

The cooling water existing outside the internal combustion engine does not receive the engine heat, and therefore is considerably lower than the temperature of the cooling water in the internal combustion engine. Therefore, when such low-temperature cooling water flows into the internal combustion engine due to the start of circulation of the cooling water, the temperature of the internal combustion engine rapidly decreases, and a thermal shock is applied to the internal combustion engine. When a thermal shock is applied to the internal combustion engine in this manner, the durability of the internal combustion engine may decrease due to thermal stress, and the sealing performance of cooling water or lubricating oil may decrease.

The present invention has been made in view of such conventional circumstances, and an object thereof is to suppress a thermal shock to the internal combustion engine that may occur when the circulation stop of the cooling water is released.

In order to achieve the above object, the present invention provides an engine cooling system in which cooling water circulates, a temperature detection unit that detects a first temperature that is the temperature of the cooling water in the internal combustion engine, and without depending on the engine operating state An internal combustion engine cooling device comprising: a pump capable of changing a discharge amount of the cooling water; and a control unit that controls the pump so that the circulation of the cooling water is stopped when the first temperature is lower than a predetermined temperature. The control unit determines a discharge amount of the pump when the circulation stop of the cooling water is released at a temperature of the cooling water existing outside the internal combustion engine in the engine cooling system and the temperature during the circulation stop. A setting process for setting based on a certain second temperature is performed.

According to this configuration, the discharge amount of the pump when the cooling water circulation stop is released is the temperature of the cooling water existing outside the internal combustion engine in the engine cooling system and the temperature during the circulation stop. 2 Set based on temperature. For this reason, the amount of cooling water having a temperature lower than that of the internal combustion engine flows into the internal combustion engine is set according to the temperature of the cooling water existing outside the internal combustion engine when the circulation is stopped. Therefore, it is possible to suppress a thermal shock to the internal combustion engine that may occur when the circulation stop of the cooling water is released.

In this configuration, it is desirable to set the pump discharge amount based on the second temperature immediately before the cooling water circulation stop is released.
Further, the present invention can be embodied in such a manner that the control unit decreases the discharge amount of the pump as the second temperature is lower.

According to this configuration, the amount of cooling water flowing into the internal combustion engine can be reduced as the temperature of the cooling water flowing into the internal combustion engine is lower. Therefore, the thermal shock to the internal combustion engine can be appropriately suppressed.

The present invention embodies this in an aspect in which the control unit sets the discharge amount of the pump when the circulation stop of the cooling water is released based on one of the outside air temperature and the intake air temperature. be able to.

In the engine cooling system, the temperature of the cooling water existing outside the internal combustion engine and the second temperature when the circulation is stopped can be directly detected by a sensor or the like. On the other hand, when the internal combustion engine is started from a cold state, the second temperature is substantially the same as the outside air temperature or the intake air temperature. Therefore, as in the same configuration, a sensor for detecting the second temperature is provided by setting the discharge amount of the pump when the cooling water circulation stop is released based on either the outside air temperature or the intake air temperature. Therefore, the discharge amount can be set according to the second temperature.

In the aspect of the present invention, the control unit performs a correction process for correcting the discharge amount of the pump set by the setting process so as to increase as the first temperature at the time of starting the engine increases. This can be embodied.

When the internal combustion engine is started from a cold state, the second temperature is substantially the same as the outside air temperature or the intake air temperature. On the other hand, if the internal combustion engine is stopped during warm-up or after completion of warm-up, and then restarted before the engine becomes cold, the cooling water circulates during or after warm-up. There is a possibility that the second temperature is higher than the outside air temperature or the intake air temperature. In such a case, since the temperature difference between the second temperature and the cooling water in the internal combustion engine is relatively small, the discharge amount is larger than the discharge amount set based on either the outside air temperature or the intake air temperature. Even if the amount is set, there is a low possibility that the thermal shock as described above is greatly applied.

Here, there is a possibility that the second temperature is higher than the outside air temperature or the intake air temperature as the first temperature at the start of the engine (the temperature of the cooling water in the internal combustion engine) is higher. For this reason, in this configuration, the discharge amount of the pump set based on the second temperature is corrected so as to increase as the first temperature at the start of the engine increases. Accordingly, when the pump discharge amount is set based on the outside air temperature or the intake air temperature, it is possible to prevent the pump discharge amount from being unnecessarily reduced when the cooling water circulation is started. .

Therefore, for example, the following inconvenience can be suppressed. That is, when the cooling water in the internal combustion engine reaches the predetermined temperature, the circulation of the cooling water is started. At that time, the temperature of the cooling water flowing into the internal combustion engine is relatively high and the inflow amount is small. In some cases, less heat is transferred from the internal combustion engine to the cooling water. For this reason, the temperature increase rate of the internal combustion engine does not greatly change before the start of the circulation of the cooling water, and in some cases, there is a concern that the temperature of the internal combustion engine may overshoot the optimum temperature. The According to this configuration, since it is possible to suppress that the discharge amount of the pump when starting the circulation of the cooling water is unnecessarily reduced, it is possible to suppress the occurrence of such an overshoot. Become.

The present invention, the engine cooling system includes a radiator that cools the cooling water, and a switching unit that switches between circulation and suspension of the cooling water to the radiator according to the temperature of the cooling water,
The predetermined temperature may be embodied in such a manner that the switching unit is set to a temperature lower than the temperature of the cooling water at which the circulation of the cooling water to the radiator is started by the switching unit.

According to this configuration, the cooling water flows into the internal combustion engine without being cooled by the radiator between the start of the circulation of the cooling water and the start of the circulation of the cooling water to the radiator. Therefore, it is possible to more suitably suppress the low-temperature cooling water from flowing into the internal combustion engine when starting the circulation of the cooling water.

In the present invention, the control unit cools the driving mode of the pump after the first temperature reaches the predetermined temperature until the first temperature reaches a second predetermined temperature higher than the predetermined temperature. As the intermittent operation in which water is intermittently discharged, the pump is driven in a low flow rate mode in which the discharge amount is limited, and when the first temperature becomes equal to or higher than the second predetermined temperature, the driving mode of the pump This can be embodied in such a manner that the operation is changed to a continuous operation in which the cooling water is continuously discharged.

According to the same configuration, when the temperature of the cooling water rises from a state where the circulation of the cooling water is stopped and reaches a predetermined temperature, the operation of the pump is started. In this case, the pump is first driven in a low flow rate mode in which the drive mode is intermittent operation and the discharge amount is limited to a low flow rate. In this way, the cooling water is circulated in a state where the pump discharge amount is limited to a low flow rate, so that the thermal shock that may be caused by the low-temperature cooling water flowing into the high-temperature internal combustion engine is appropriately prevented. Can be relaxed. Further, by circulating the cooling water, local boiling of the cooling water in the vicinity of the high temperature portion of the internal combustion engine can be suppressed. In addition, in this low flow rate mode, the pump is intermittently operated, so that the average discharge amount of the pump in a predetermined period can be set to an extremely low flow rate. Accordingly, it is possible to circulate a suitable amount of cooling water in order to reduce the thermal shock when the cooling water in the low temperature state flows into the internal combustion engine in the high temperature state while suppressing local boiling of the cooling water.

Then, when the temperature of the cooling water further rises, the driving mode of the pump is changed to continuous operation, and the pump discharge amount is increased as compared with the previous low flow rate mode. As a result, a sufficient circulation amount of the cooling water can be secured, and the engine cooling system can be cooled in accordance with the engine temperature state at that time even after complete warm-up.

Further, as the pump of the present invention, an electric pump can be employed, or a mechanical drive pump coupled to the engine output shaft via a clutch and driven by the engine output shaft can be employed. . In a mechanically driven pump, when the clutch is engaged, the pump discharge amount is determined based on the rotation of the engine drive shaft. On the other hand, when the clutch is in the disengaged state, discharge of the cooling water by the pump is stopped regardless of the rotational state of the engine drive shaft. Further, by intermittently engaging the clutch, the drive mode of the pump can be intermittently operated.

1 is a schematic configuration diagram showing an internal combustion engine and a cooling device thereof according to a first embodiment of the present invention. The flowchart which shows the drive processing procedure of the electric pump in the embodiment. The flowchart which shows the discharge amount setting process sequence of the electric pump in the embodiment. The graph which shows the relationship between intake temperature and the discharge amount of an electric pump. The timing chart which shows the example about the drive mode of the electric pump in the embodiment. The flowchart which shows the discharge amount setting process sequence of the electric pump in 2nd Embodiment. The graph which shows the relationship between the cooling water temperature at the time of a start, and the discharge amount correction value of an electric pump. The graph which shows the relationship between the discharge amount of the electric pump and intake air temperature in the modification of 1st Embodiment. The graph which shows the relationship between the discharge amount correction value of the electric pump in the modification of 2nd Embodiment, the cooling water temperature at the time of a stop, and an engine stop time. The schematic block diagram which shows the modification of the water pump of 1st Embodiment.

(First embodiment)
A first embodiment of a cooling device according to the present invention will be described below with reference to FIGS.

As shown in FIG. 1, a cooling device for an internal combustion engine 10 mounted on a vehicle generally includes a water jacket 13 formed around an engine combustion chamber 10a inside a cylinder block 11 and a cylinder head 12, and the water jacket 13. An electric pump 23 for discharging cooling water to the jacket 13 and a main passage 24 and a sub passage 27 for circulating the cooling water in the water jacket 13 back to the electric pump 23 are constituted.

The main passage 24 connects the water jacket 13 and the electric pump 23 via the radiator 21 and the thermostat 22. The radiator 21 releases heat of the cooling water to the outside by performing heat exchange between the cooling water and the outside air.

The thermostat 22 is a temperature-sensitive type in which the position of the valve body provided therein changes according to the temperature of the cooling water, and the circulation and stoppage of the cooling water to the radiator 21 depend on the position of the valve body. It functions as a switching unit that can be switched. The valve body of the thermostat 22 is kept closed when the temperature of the cooling water is lower than the valve opening start temperature. When the temperature of the cooling water reaches the valve opening start temperature, the valve body is gradually opened, and when the temperature of the cooling water reaches the full valve opening temperature, the valve body is kept open at the maximum opening. Is done.

On the other hand, the sub passage 27 connects the water jacket 13 and the electric pump 23 via the thermal device system 14 and the thermostat 22. The thermal device system 14 includes various devices that use heat of cooling water such as a heater core, a heating passage of a throttle body, and an EGR cooler. The sub passage 27 is always in communication with the electric pump 23 regardless of whether the thermostat 22 is open or closed. Therefore, when the thermostat 22 is in the closed state, the cooling water discharged from the electric pump 23 to the water jacket 13 flows through the sub passage 27 including the thermal equipment system 14 and is returned to the electric pump 23, and again the water jacket 13. Discharged. On the other hand, the cooling water does not flow into the radiator 21 through the main passage 24.

On the other hand, when the thermostat 22 is in the valve open state, the cooling water discharged from the electric pump 23 to the water jacket 13 is returned to the electric pump 23 from the sub-passage 27 and then again watered. It is discharged to the jacket 13. In addition to this, the cooling water flows from the water jacket 13 through the main passage 24 including the radiator 21, is returned to the electric pump 23, and is discharged to the water jacket 13 again.

The electric pump 23 sucks and discharges the cooling water when the impeller connected to the output shaft of the motor rotates. The amount of cooling water discharged from the electric pump 23 increases as the rotational speed of the output shaft (hereinafter referred to as pump rotational speed) increases. The pump rotation speed changes according to the ratio between the energization time and the energization stop time of the motor (hereinafter referred to as duty ratio DT), and increases as the duty ratio DT increases.

The motor of the electric pump 23 is connected to the control device 91, and the driving mode of the motor is controlled through the control device 91. For example, the control device 91 selects a continuous operation for continuously discharging cooling water and an intermittent operation for intermittently discharging cooling water as the driving mode of the electric pump 23.

When the continuous operation is selected, the circulation amount of the cooling water is adjusted by changing the discharge amount of the electric pump 23. On the other hand, when intermittent operation is selected, the circulation amount of the cooling water is adjusted by changing the ratio of the driving period that is the period for discharging the cooling water and the stopping period that is the period for stopping the cooling water discharge. Is done.

In this embodiment, the main passage 24, the sub passage 27, the water jacket 13, the electric pump 23, the thermostat 22, the radiator 21, and the thermal equipment system 14 constitute an engine cooling system.

The control device 91 includes a water temperature sensor 92 that is provided in the vicinity of the outlet of the water jacket 13 and detects the temperature of the cooling water in the internal combustion engine 10 (hereinafter referred to as the first cooling water temperature) THW1, and the intake passage of the internal combustion engine 10. Is connected to an intake air temperature sensor 93 for detecting intake air temperature (hereinafter referred to as intake air temperature) THA. Various other sensors such as a rotation speed sensor 94 that detects the engine rotation speed are also connected to the control device 91. The control device 91 controls the driving mode of the electric pump 23 based on the detection values of these sensors. The intake air temperature THA changes with a certain degree of correlation with the outside air temperature, and is therefore used as a substitute value for the outside air temperature. Further, the water temperature sensor 92 constitutes the temperature detection unit that detects the first temperature that is the temperature of the cooling water in the internal combustion engine 10.

Next, drive control of the electric pump 23 by the control device 91 will be described.
When the temperature of the internal combustion engine 10 is low, such as during a cold start, the control device 91 promotes warming up of the internal combustion engine 10 by stopping the driving of the electric pump 23 and stopping the circulation of the cooling water. The wall surface temperature of the combustion chamber 10a is maintained at a high temperature to reduce heat loss and thus improve fuel efficiency. Then, after the first cooling water temperature THW1 rises to a predetermined reference temperature and the warm-up of the internal combustion engine 10 has progressed to some extent, the control device 91 performs an electric pump to cool the internal combustion engine 10 with the cooling water. 23 is driven to start circulating the cooling water.

By the way, when the circulation of the cooling water is started in this way, the cooling water existing outside the internal combustion engine 10 in the engine cooling system, that is, the cooling water stagnating in the sub passage 27 flows into the internal combustion engine. To come.

The cooling water stagnating in the sub-passage 27 has not received the engine heat until then, and therefore is considerably lower than the temperature of the cooling water in the internal combustion engine 10. Therefore, when such low-temperature cooling water flows into the internal combustion engine 10, the temperature of the internal combustion engine 10 rapidly decreases and a thermal shock is applied to the internal combustion engine 10. When a thermal shock is applied to the internal combustion engine 10 in this way, the durability of the internal combustion engine is reduced due to thermal stress, or the cooling water or lubricating oil seal is caused by the difference in the amount of thermal contraction between the cylinder head 12 and the cylinder block 11. There is a risk of performance degradation.

The cylinder head 12 is formed with an exhaust port through which high-temperature exhaust flows. In general, the volume of the cylinder head 12 is smaller than that of the cylinder block. Therefore, the temperature of the cylinder head 12 tends to be higher than that of the cylinder block 11, and the thermal shock as described above tends to act on the cylinder head 12 more strongly than the cylinder block 11.

Therefore, in order to suppress the thermal shock, the control device 91 executes a pump driving process shown in FIG. The series of processing shown in FIG. 2 is repeatedly executed by the control device 91 every predetermined calculation cycle from the time of engine start.

When this process is started, first, the control device 91 determines whether or not the first cooling water temperature THW1 is equal to or higher than the first reference temperature TX1 (S10). The first reference temperature TX1 is a first value indicating whether the internal combustion engine 10 is in a low temperature state, more specifically, whether there is a possibility of local boiling of cooling water in the vicinity of the engine combustion chamber 10a. As a value for determination by comparison with the cooling water temperature THW1, it is set in advance through a test or the like. The first reference temperature TX1 is set to a temperature lower than the valve opening start temperature of the thermostat 22.

When the first coolant temperature THW1 is lower than the first reference temperature TX1 (S10: NO), the control device 91 stops driving the electric pump 23 because the internal combustion engine 10 is in a low temperature state (S50). ). As a result, the circulation of the cooling water is stopped and the warm-up of the internal combustion engine 10 is promoted.

On the other hand, when the first coolant temperature THW1 is equal to or higher than the first reference temperature TX1 (S10: YES), the control device 91 determines whether or not the first coolant temperature THW1 is equal to or higher than the second reference temperature TX2. Determine (S20). The second reference temperature TX2 is a value for determining whether or not the warm-up of the internal combustion engine 10 is completed by comparing with the first coolant temperature THW1, and is set in advance through a test or the like. The second reference temperature TX2 is set to a temperature higher than the first reference temperature TX1. The second reference temperature TX2 is set to a temperature lower than the complete valve opening temperature of the thermostat 22.

When the first cooling water temperature THW1 is equal to or higher than the second reference temperature TX2 (S20: YES), since the warm-up of the internal combustion engine 10 is completed, the control device 91 sets the electric pump 23 in the normal mode. (S30). In this normal mode, the control device 91 sets the discharge amount QN of the electric pump 23 based on parameters indicating the engine operation state such as the first coolant temperature THW1, the engine load, and the engine rotation speed, and the set discharge amount. The electric pump 23 is continuously operated so as to obtain QN.

On the other hand, when the first cooling water temperature THW1 is lower than the second reference temperature TX2 (S20: NO), it is determined that the warm-up of the internal combustion engine 10 has not been completed, and the control device 91 turns the electric pump 23 off. Drive in the low flow rate mode (S40). In this low flow rate mode, the control device 91 executes the discharge amount setting process shown in FIG. 3, and controls the drive of the electric pump 23 so as to achieve the set discharge amount.

Thus, after setting the drive mode of the electric pump 23 in steps S30, S40, and S50, the control device 91 once ends this process.
The control device 91 that performs the pump driving process and the discharge amount setting process constitutes the control unit.

Next, the discharge amount setting process will be described with reference to FIG. This discharge amount setting process is executed by the control device 91 when the low flow rate mode is executed.
When this process is started, the control device 91 first reads the intake air temperature THA (S100). Then, the control device 91 calculates the discharge amount QL of the electric pump 23 based on the intake air temperature THA (S110), and this process is terminated. In step S110, as shown in FIG. 4, the discharge amount QL is calculated to be smaller as the intake air temperature THA is lower. The reason for setting the discharge amount QL in this manner is as follows.

First, the temperature of the cooling water existing outside the internal combustion engine 10 in the engine cooling system and the temperature when the cooling water is circulated and stopped is defined as a second temperature THW2. That is, the temperature of the cooling water stagnating in the sub passage 27 while the cooling water circulation is stopped is set to the second temperature THW2. The second temperature THW2 is substantially the same as the outside air temperature or the intake air temperature when the internal combustion engine 10 is started from a cold state. Therefore, it is possible to estimate the second temperature THW2 based on the intake air temperature THA.

In step S110, the discharge amount QL is decreased as the intake air temperature THA is lower, that is, as the second temperature THW2 is lower. Therefore, the amount of cooling water flowing into the internal combustion engine 10 is reduced as the temperature of the cooling water flowing into the internal combustion engine 10 is lower due to the start of the circulation of the cooling water. Therefore, the rapid temperature drop of the internal combustion engine 10 due to the start of the cooling water circulation is appropriately suppressed, and the thermal shock to the internal combustion engine 10 is suppressed.

When the discharge amount QL is set in step S110, the control device 91 is electrically driven based on the discharge amount QL set based on the intake air temperature THA just before the cooling water circulation stop is canceled in the previous step S40. The pump 23 is driven in the low flow rate mode. In this low flow rate mode, the ratio of the drive period, which is a period for discharging cooling water, and the stop period, which is a period for stopping discharge of cooling water, is adjusted so that the discharge amount QL is obtained.

In this embodiment, the discharge amount when the electric pump 23 is driven in the low flow rate mode is fixed to the discharge amount QL. In addition, when the temperature of the cooling water at the highest temperature in the internal combustion engine 10 (for example, the temperature of the cooling water in the vicinity of the combustion chamber of the cylinder head 12) can be estimated, the following is performed. The discharge amount can also be set. That is, it was estimated that a suitable amount of cooling water was circulated in order to avoid the occurrence of thermal shock and increase in heat loss as described above while suppressing the occurrence of local cooling water boiling. The discharge amount QL may be corrected based on the temperature.

Next, the operation of the low flow rate mode will be described with reference to FIG.
When the internal combustion engine 10 in the cold state is started (time t0), the drive of the electric pump 23 is stopped until the first coolant temperature THW1 reaches the first reference temperature TX1 (time t1). The cooling water circulation is stopped. Therefore, the temperature of the cooling water in the internal combustion engine 10 gradually rises, and the rising speed at this time becomes faster than the case where the cooling water is circulated immediately after starting.

When the first coolant temperature THW1 reaches the first reference temperature TX1 (time t1), the discharge amount QL of the electric pump 23 is set based on the intake air temperature THA at that time, and the coolant is circulated in the low flow rate mode. Is started.

Here, the driving of the electric pump 23 is stopped until the first cooling water temperature THW1 reaches the second reference temperature TX2. Then, when the first coolant temperature THW1 reaches the second reference temperature TX2 (time t2), that is, when the warm-up of the internal combustion engine 10 is completed, the electric pump 23 continues without executing the low flow rate mode. When the operation is started, the first coolant temperature THW1 rapidly decreases as shown by a one-dot chain line in FIG. As described above, when the first cooling water temperature THW1 is rapidly decreased, the temperature of the cooling water in the internal combustion engine 10 is also rapidly decreased. Therefore, the thermal shock as described above acts on the internal combustion engine 10. .

In this respect, in the present embodiment, the driving of the electric pump 23 is started in the low flow rate mode in consideration of the temperature of the cooling water flowing into the internal combustion engine 10 at the time t1 as described above. Therefore, although the rate of increase in the temperature of the cooling water is decreased, the rapid decrease in the first cooling water temperature THW1 is suppressed and the thermal shock is also suppressed.

When the driving of the electric pump 23 in the low flow rate mode is started, the circulation of the cooling water is started, so that the cooling water stagnated in the sub passage 27 flows into the internal combustion engine 10, The temperature of the cooling water in the passage 27 gradually increases. In addition, the first cooling water temperature THW1 gradually increases in temperature although the rate of temperature increase is lower than before the start of circulation of the cooling water.

Then, when the temperature of the cooling water in the sub passage 27 reaches the valve opening start opening (time t3), the thermostat 22 starts to open. Then, when the temperature of the cooling water in the sub passage 27 reaches the full valve opening temperature (time t4), the thermostat 22 is fully opened.

After the thermostat 22 is fully opened in this way, when the first cooling water temperature THW1 reaches the second reference temperature TX2, the continuous operation of the electric pump 23 in the normal mode is started to become the discharge amount QN. The drive of the electric pump 23 is controlled (time t5).

As described above, according to the present embodiment, the following operational effects can be obtained.
(1) The discharge amount of the electric pump 23 when the cooling water circulation stop is released is the temperature of the cooling water existing outside the internal combustion engine 10 in the engine cooling system and the temperature during the circulation stop. Two temperatures are set based on THW2. Therefore, the amount of cooling water having a temperature lower than that of the internal combustion engine 10 flows into the internal combustion engine 10 is set according to the temperature of the cooling water existing outside the internal combustion engine 10 when the circulation is stopped. Accordingly, it is possible to suppress a thermal shock to the internal combustion engine 10 that may occur when the circulation stop of the cooling water is released.
(2) The discharge amount QL is variably set so that the discharge amount QL of the electric pump 23 decreases as the second temperature THW2 is lower. Therefore, the amount of cooling water flowing into the internal combustion engine 10 can be reduced as the temperature of the cooling water flowing into the internal combustion engine 10 with the start of circulation of the cooling water is lower. Therefore, the thermal shock to the internal combustion engine 10 can be appropriately suppressed.
(3) The temperature of the cooling water existing outside the internal combustion engine 10 in the engine cooling system and the second temperature THW2 when the circulation is stopped can be directly detected by a sensor or the like. On the other hand, when the internal combustion engine 10 is started from a cold state, the second temperature THW2 is substantially the same as the outside air temperature or the intake air temperature THA. Therefore, the discharge amount QL is set on the basis of the intake air temperature THA, so that the discharge amount QL corresponding to the second temperature THW2 can be set without providing a sensor for detecting the second temperature THW2. Will be able to.
(4) The first reference temperature TX1 for starting the low flow rate mode is set lower than the valve opening start temperature of the thermostat 22. Therefore, the cooling water flows into the internal combustion engine 10 without being cooled by the radiator 21 after the cooling water circulation is started until the cooling water circulation to the radiator 21 is started. Therefore, it is possible to more suitably suppress the low-temperature cooling water from flowing into the internal combustion engine 10 at the start of the cooling water circulation.
(5) After the first coolant temperature THW1 reaches the first reference temperature TX1, the electric pump 23 is driven until the first coolant temperature THW1 reaches the second reference temperature TX2 higher than the first reference temperature TX1. The mode is driven in a low flow rate mode in which the discharge amount is limited as an intermittent operation in which cooling water is intermittently discharged. Further, when the first cooling water temperature THW1 becomes equal to or higher than the second reference temperature TX2, the driving mode of the electric pump 23 is changed to the continuous operation in which the cooling water is continuously discharged.

Therefore, when the temperature of the cooling water rises from the state where the circulation of the cooling water is stopped and reaches the first reference temperature TX1, the operation of the electric pump 23 is started. In this case, first, the electric pump 23 is driven in a low flow rate mode in which the drive mode is intermittent operation and the discharge amount is limited to a low flow rate. Thus, since the cooling water is circulated in a state where the discharge amount of the electric pump 23 is limited to a low flow rate, the thermal shock that may be generated when the cooling water in the low temperature state flows into the internal combustion engine 10 in the high temperature state. Can be moderated appropriately. Further, by circulating the cooling water, it is possible to suppress local boiling of the cooling water near the high temperature portion of the internal combustion engine 10 (for example, near the combustion chamber of the cylinder head 12). Moreover, since the electric pump 23 is intermittently operated in this low flow rate mode, the average discharge amount of the electric pump 23 in a predetermined period can be set to an extremely low flow rate. Therefore, it is possible to distribute a suitable amount of cooling water in order to mitigate the thermal shock when the cooling water in the low temperature state flows into the internal combustion engine 10 in the high temperature state while suppressing local boiling of the cooling water. .

Then, when the temperature of the cooling water further rises, the driving mode of the electric pump 23 is changed to continuous operation, and the discharge amount of the electric pump 23 is increased as compared with the previous low flow rate mode. As a result, a sufficient circulation amount of the cooling water can be secured, and the engine cooling system can be cooled in accordance with the engine temperature state at that time even after complete warm-up.

(Second Embodiment)
Next, a second embodiment in which the cooling device according to the present invention is embodied will be described with reference to FIGS.

This embodiment is configured as a partial modification of the discharge amount setting process of the first embodiment. Details of the changed configuration will be described below. In addition, since the structure similar to 1st Embodiment is employ | adopted about the other point, about the common structure, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

As described above, when the internal combustion engine 10 is started from a cold state, the second temperature THW2 becomes substantially the same as the outside air temperature or the intake air temperature THA.
On the other hand, when the internal combustion engine 10 is stopped during the warm-up or after the completion of the warm-up, and then restarted before the engine is in the cold state, the cooling water is in the middle of the warm-up or after the completion of the warm-up. Circulation is performed, and there is a possibility that the second temperature THW2 is higher than the outside air temperature or the intake air temperature THA. In such a case, since the temperature difference between the second temperature THW2 and the cooling water in the internal combustion engine 10 is relatively small, a discharge amount larger than the discharge amount QL set based on the intake air temperature THA is set. Even so, there is a low possibility that the thermal shock as described above is greatly applied.

Here, as the first cooling water temperature THW1 (the temperature of the cooling water in the internal combustion engine) at the time of starting the engine is higher, the second temperature THW2 may be higher than the outside air temperature or the intake air temperature THA. . Therefore, in the present embodiment, the discharge amount QL of the electric pump 23 set based on the second temperature THW2 is corrected so as to increase as the first coolant temperature THW1 at the time of engine start increases. .

FIG. 6 shows a processing procedure of the discharge amount setting process in the present embodiment. This discharge amount setting process is also executed by the control device 91 when the low flow rate mode is executed, as in the first embodiment.

When this process is started, first, the control device 91 reads the starting coolant temperature THW1s, which is the first coolant temperature THW1 immediately after the engine is started, and the current intake air temperature THA (S200). The control device 91 stores the first cooling water temperature THW1 detected by the water temperature sensor 92 immediately after the engine is started in the storage device, and in step S200, the first cooling water temperature THW1 stored in the storage device is stored. Read as the starting coolant temperature THW1s.

Then, the control device 91 calculates the discharge amount QL of the electric pump 23 based on the intake air temperature THA (S210). The setting of the discharge amount QL performed in step S210 is the same as the setting of the discharge amount QL performed in step S110. That is, as shown in FIG. 4, the control device 91 calculates the discharge amount QL to be smaller as the intake air temperature THA is lower.

Next, the control device 91 calculates a discharge amount correction value QLH based on the starting coolant temperature THW1s (S220). As shown in FIG. 7, the control device 91 sets the discharge amount correction value QLH so that the discharge amount correction value QLH increases as the starting coolant temperature THW1s increases. The minimum value of the discharge amount correction value QLH is “1”.

Next, the control device 91 corrects the discharge amount QL by multiplying the discharge amount QL calculated in step S210 by the discharge amount correction value QLH calculated in step S220 (S230). And the control apparatus 91 complete | finishes this process.

In this way, by multiplying the discharge amount QL by the discharge amount correction value QLH, the discharge amount QL of the electric pump 23 set based on the intake air temperature THA increases as the starting coolant temperature THW1s increases. It is corrected to.

Then, when the discharge amount QL is corrected in step S230, the control device 91 drives the electric pump 23 in the low flow rate mode based on the corrected discharge amount QL in the previous step S40. In this low flow rate mode, the ratio of the drive period, which is a period for discharging cooling water, and the stop period, which is a period for stopping discharge of cooling water, is adjusted so that the discharge amount QL is obtained.

According to the present embodiment described above, the following functions and effects can be obtained in addition to the functions and effects described in (1) to (5) above.
(6) The discharge amount QL of the electric pump 23 set based on the intake air temperature THA is corrected so as to increase as the starting coolant temperature THW1s increases. Therefore, in the case where the discharge amount QL of the electric pump 23 is set based on the intake air temperature THA, it is possible to prevent the discharge amount QL of the electric pump 23 from being unnecessarily reduced when the circulation of the cooling water is started. become able to.

Therefore, for example, the following inconvenience can be suppressed. That is, when the cooling water in the internal combustion engine 10 reaches the first reference temperature TX1, circulation of the cooling water is started. At that time, the temperature of the cooling water flowing into the internal combustion engine 10 is relatively high, and When the inflow amount is small, the amount of heat transferred from the internal combustion engine 10 to the cooling water decreases. Therefore, the temperature increase rate of the internal combustion engine 10 does not change significantly before the start of the circulation of the cooling water, and in some cases, the temperature of the internal combustion engine 10 overshoots the optimum temperature. Concerned. In this regard, according to the present embodiment, it is possible to suppress the discharge amount QL of the electric pump 23 when starting the circulation of the cooling water from being unnecessarily reduced. It becomes possible to suppress.

(Other embodiments)
In addition, the embodiment of the present invention is not limited to the embodiment exemplified in each of the above-described embodiments, and can be implemented by changing it as shown below, for example. The following modifications are not applied only to the above embodiments, and different modifications can be combined with each other.

In the first and second embodiments, as shown in FIG. 4, the discharge amount QL is continuously variably set so that the discharge amount QL increases as the intake air temperature THA increases. In addition, a plurality of temperature regions may be set for the intake air temperature THA, and the discharge amount QL may be set for each temperature region.

For example, as shown in FIG. 8, temperature regions THA1 to THA5 are set in ascending order of temperature. Then, the discharge amount QL is set for each of the temperature regions THA1 to THA5. At this time, the discharge amount QL corresponding to the higher temperature region is set so that the value becomes larger. In this case, the discharge amount QL can be set with a simpler configuration.

In the second embodiment, the discharge amount correction value QLH is set based on the starting coolant temperature THW1s. The first cooling water temperature THW1 at the time of starting the engine is such that the longer the elapsed time from when the internal combustion engine 10 is stopped until it is started, or the first cooling water temperature THW1 when the internal combustion engine 10 is stopped. The lower, the lower. Therefore, as shown in FIG. 9, the first coolant temperature when the engine stop time PST, which is the elapsed time from when the internal combustion engine 10 is stopped to when it is started, is longer, or when the internal combustion engine 10 is stopped. The discharge amount correction value QLH may be set so that the discharge amount correction value QLH increases as the stop-time cooling water temperature THW1p, which is THW1, is lower. Even in this case, the effect according to the second embodiment can be obtained.

In the second embodiment, the discharge amount correction value QLH for correcting the discharge amount QL is set based on the starting coolant temperature THW1s. In addition, the intake air temperature THA may be corrected based on the starting coolant temperature THW1s.

For example, the intake air temperature correction value THAH is calculated based on the starting coolant temperature THW1s. The intake air temperature correction value THAH is variably set so that the value increases as the starting coolant temperature THW1s increases. The minimum value of the intake air temperature correction value THAH is “1”. Then, the intake air temperature THA is calculated by multiplying the intake air temperature THA by the intake air temperature correction value THAH. By correcting the intake air temperature THA in this way, the corrected intake air temperature THA is calculated such that the value increases as the starting coolant temperature THW1s increases. That is, as the first coolant temperature THW1 at the time of starting the engine is higher, the second temperature THW2 may be higher than the intake air temperature THA. Therefore, the second temperature THW2 is substituted according to the tendency. The intake air temperature THA used as a value is corrected. Then, based on the corrected intake air temperature THA, the discharge amount QL is set in the manner shown in FIG. Also in this case, since the discharge amount QL of the electric pump 23 can be corrected so as to increase as the starting coolant temperature THW1s is higher, the operational effect according to the second embodiment can be obtained.

As described above, when the internal combustion engine 10 is started from a cold state, the second temperature THW2 is substantially the same as the outside air temperature or the intake air temperature. Therefore, when an outside air temperature sensor is provided, the discharge amount QL of the electric pump 23 in the low flow rate mode may be set based on the outside air temperature instead of the intake air temperature THA.

In addition, a sensor is provided for detecting the temperature of the cooling water existing outside the internal combustion engine 10 while the cooling water circulation is stopped, for example, the cooling water stagnating in the sub-passage 27. The discharge amount QL may be set based on the two temperature THW2. Thus, when the second temperature THW2 is actually detected, the discharge amount QL can be set to an appropriate value with higher accuracy.

In the low flow mode, the electric pump 23 is intermittently operated to realize an extremely low flow rate. In addition, when an electric pump capable of realizing an extremely low flow rate even by continuous operation is employed, the electric pump may be continuously operated so as to obtain the discharge amount QL in the low flow rate mode. .

The valve opening start temperature of the thermostat 22 and the first reference temperature TX1 may be the same. Even in this case, the effects described in (1) to (3), (5), and (6) can be obtained.

-Although a thermosensitive type was adopted as the thermostat 22, it can be changed to an electronically controlled thermostat.
-The electric pump 23 was adopted as a water pump for circulating the cooling water. In addition, a mechanically driven pump that is connected to the engine output shaft via a clutch and driven by the engine output shaft may be employed. FIG. 10 shows an example of a configuration when a mechanical drive pump is employed. As shown in FIG. 10, the mechanically driven pump includes a water pump 230 having an input shaft 235 that rotates integrally with an impeller, and a clutch mechanism that is connected to the input shaft 235 and whose engagement state is switched by an actuator 310. 300 and a pulley 400 connected to the clutch mechanism 300. The pulley 400 rotates integrally with the pulley 600 connected to the crankshaft 50 of the internal combustion engine 10 via the belt 500. Further, the engagement state of the clutch mechanism 300 is switched by controlling the operation of the actuator 310 by the control device 91.

In this mechanically driven pump, when the clutch mechanism 300 is engaged, the discharge amount of the pump is determined based on the rotation of the crankshaft. On the other hand, when the clutch mechanism 300 is in the released state, discharge of the cooling water by the pump is stopped regardless of the rotation state of the crankshaft. Further, by intermittently engaging the clutch mechanism 300, the drive mode of the pump can be intermittently operated.

DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 10a ... Engine combustion chamber, 11 ... Cylinder block, 12 ... Cylinder head, 13 ... Water jacket, 14 ... Thermal equipment system, 21 ... Radiator, 22 ... Thermostat, 23 ... Electric pump, 24 ... Main passage, 27 ... sub-passage, 50 ... crankshaft, 91 ... control device, 92 ... water temperature sensor, 93 ... intake air temperature sensor, 94 ... rotational speed sensor, 230 ... water pump, 235 ... input shaft, 300 ... clutch mechanism, 310 ... actuator , 400 ... pulley, 500 ... belt, 600 ... pulley.

Claims

An engine cooling system through which cooling water circulates;
A temperature detection unit that detects a first temperature that is a temperature of cooling water in the internal combustion engine;
A pump capable of changing the discharge amount of cooling water without depending on the engine operating state;
A cooling device for an internal combustion engine comprising: a control unit that controls the pump so that the circulation of cooling water stops when the first temperature is lower than a predetermined temperature;
The controller controls the discharge amount of the pump when the cooling water circulation stop is released, the temperature of the cooling water existing outside the internal combustion engine in the engine cooling system, and the temperature during the circulation stop. A cooling apparatus for an internal combustion engine, wherein a setting process for setting based on the second temperature is performed.
The cooling device for an internal combustion engine according to claim 1, wherein the control unit decreases the discharge amount of the pump as the second temperature is lower.
The cooling device for an internal combustion engine according to claim 1 or 2, wherein the control unit sets the discharge amount of the pump when the circulation stop of the cooling water is released based on either the outside air temperature or the intake air temperature.
The internal combustion engine according to claim 3, wherein the control unit performs a correction process for correcting the discharge amount of the pump set by the setting process so as to increase as the first temperature at the time of starting the engine increases. Cooling system.
The engine cooling system includes a radiator that cools the cooling water, and a switching unit that switches between circulating and stopping the cooling water according to the temperature of the cooling water.
The cooling of the internal combustion engine according to any one of claims 1 to 4, wherein the predetermined temperature is set to a temperature lower than a temperature of the cooling water at which the circulation of the cooling water to the radiator is started by the switching unit. apparatus.
After the first temperature reaches the predetermined temperature, the control unit intermittently cools the drive mode of the pump until the first temperature reaches a second predetermined temperature higher than the predetermined temperature. When the pump is driven in a low flow rate mode in which the discharge amount is limited as an intermittent operation to be discharged to the pump, and the first temperature becomes equal to or higher than the second predetermined temperature, the pump is driven by cooling water. The cooling device for an internal combustion engine according to any one of claims 1 to 5, wherein the operation is changed to a continuous operation in which the discharge is continuously performed.
The cooling apparatus for an internal combustion engine according to any one of claims 1 to 6, wherein the pump is an electric pump.
The cooling apparatus for an internal combustion engine according to any one of claims 1 to 6, wherein the pump is a mechanically driven pump that is connected to an engine output shaft via a clutch and driven by the engine output shaft.