WO2011089705A1

WO2011089705A1 - Cooling device for vehicle

Info

Publication number: WO2011089705A1
Application number: PCT/JP2010/050771
Authority: WO
Inventors: 治新谷; 茂樹木野村; 太郎古越; 篤史駒田
Original assignee: トヨタ自動車株式会社
Priority date: 2010-01-22
Filing date: 2010-01-22
Publication date: 2011-07-28

Abstract

A thermostat (7) that prohibits and allows the passage of coolant in a first coolant circuit through the inside of an engine (1) includes a valve body urged by a spring in a direction along which the valve body is closed and a thermoelement that opens the valve body against the urging force of the spring. The thermoelement pushes out or draws a shaft using thermal expansion or thermal shrinkage of wax enclosed inside thereof. Moreover, the thermostat (7) is provided with an element heater that heats the thermoelement. When the temperature of the thermoelement is low and the valve body of the thermostat (7) is closed, the thermoelement is heated by the element heater such that the temperature of the thermoelement rises while the valve body is kept closed. With this, when the thermoelement is heated by the element heater such that the valve body of the thermostat (7) is opened on the basis of a request to open the valve body, the temperature of the thermoelement rises to a value at which the valve body can be quickly opened.

Description

Vehicle cooling device

The present invention relates to a vehicle cooling device.

As a cooling device for a vehicle, a cooling water circuit in which cooling water circulates through the inside of the engine by driving a pump is provided, and a valve body is opened and closed according to the temperature of the cooling water downstream of the engine of the cooling water circuit. There has been known one provided with a thermostat for prohibiting or allowing passage of cooling water inside the engine.

As such a thermostat, it is possible to apply what is shown by patent document 1, for example. When the temperature of the cooling water is low, the thermostat closes the valve body and prohibits the passage of the cooling water inside the engine. As a result, when the temperature of the cooling water is low and the engine is in a cold state, the passage of the cooling water inside the engine is prohibited and the heat of the engine is not taken away by the cooling water. It becomes possible to plan. Further, when the temperature of the cooling water is high, the thermostat allows the passage of the cooling water inside the engine by opening the valve body by a thermo element that receives heat transfer from the cooling water. As a result, when the temperature of the cooling water is high, the passage of the cooling water inside the engine is allowed and the high-temperature cooling water does not stay inside the engine, so the boiling of the cooling water inside the engine is suppressed. Is possible.

By the way, when the temperature of the cooling water in the cooling water circuit is low, such as immediately after starting the engine from a cold state, the temperature of the thermo element is also low and the valve body of the thermostat is closed, thereby warming up the engine. The machine is promoted. In this state, if heat generation in the combustion chamber increases due to high engine load operation, the valve body of the thermostat is closed and passage of cooling water inside the engine is prohibited. A situation occurs in which only the temperature of the cooling water rises and the temperature of the cooling water around the thermoelement does not rise. Under such circumstances, the cooling water staying in the cylinder head of the engine receives heat from the combustion chamber, so that the temperature of the cooling water rises excessively and the cooling water may boil. .

In order to cope with such a situation, as shown in Patent Document 2, a thermostat is provided with a heating element for heating the thermoelement, and the thermoelement is heated by the heating element, so that the temperature of the cooling water around the thermoelement is increased. It is conceivable that the valve element can be opened even when the value is low. In this case, when the temperature of the cooling water in the cylinder head of the engine becomes a value that may be boiled with the valve body of the thermostat closed, the valve element is heated by heating the thermo element with the heating element of the thermostat. Is opened. By thus opening the valve body and allowing water to flow into the engine, the boiling of the cooling water staying in the cylinder head can be suppressed.

JP 2008-231942 (paragraph [0042], FIG. 6) JP 2003-328753 A (paragraph [0031])

As described above, when the temperature of the cooling water in the cylinder head of the engine becomes a value that may boil, by heating the thermo element with the heating element provided in the thermostat and opening the valve body, Suppression of boiling of the cooling water staying in the cylinder head can be suppressed. However, when the temperature of the cooling water around the thermo element is low, even if the thermo element is heated by the heating element, it takes a long time until the temperature of the thermo element rises and the valve element is completely opened. As described above, since the responsiveness of the valve body opening due to heating of the thermoelement by the heating element is poor, the temperature of the cooling water in the cylinder head becomes a value that may cause boiling. Even if the element is heated, the cooling water in the cylinder head may boil before the valve body is actually opened and water can be introduced into the engine.

The present invention has been made in view of such a situation, and an object of the present invention is to provide a thermostat valve element that opens and closes to prohibit or allow the passage of cooling water inside the engine by heating the thermoelement with a heating element. An object of the present invention is to provide a cooling device for a vehicle, which can quickly open the valve body after receiving an instruction to open the valve body.

In order to achieve the above object, a vehicle cooling apparatus according to the present invention includes a cooling water circuit that circulates cooling water through the inside of an engine by driving a pump, and a thermostat provided downstream of the engine in the cooling water circuit. Prepare. The thermostat closes the valve body when the temperature of the cooling water is low and prohibits the cooling water from passing through the engine. When the temperature of the cooling water is high, the thermostat receives a heat transfer from the cooling water. The valve body is opened by the element to allow the coolant to pass through the engine. In addition, the cooling device is configured to increase the temperature of the thermo element while maintaining the closed state when the valve element is closed, and the heating element that can heat the thermo element to open the valve element. A controller that causes the heating element to heat the thermo element.

When the temperature of the cooling water in the cooling water circuit and the temperature of the thermo element are low and the valve body of the thermostat is closed, heat is generated so that the temperature of the thermo element rises while maintaining the valve body closed. The thermo element is heated by the body. Therefore, when the thermoelement is heated by the heating element to open the valve body based on the valve opening request (valve opening instruction) of the thermostat, the temperature of the thermoelement quickly opens the valve element. The valve rises to a valveable value, and the valve body is thereby opened. Therefore, when the valve body of the thermostat in the valve closing state is opened by heating the thermo element with the heating element, the valve body can be opened quickly after receiving the instruction.

The control unit performs heating of the thermo element in a state in which the valve body is kept closed when the valve body is closed after the start of the vehicle start, and in the valve open state after the start of the vehicle start. It is preferable that this is also performed when a valve closing request is made. In this case, when there is a valve opening request (opening instruction) for the valve body that is in the closed state after the start of the vehicle, the valve body in the open state is further closed based on the valve closing request for the valve body. When there is a valve opening request (opening instruction) after shifting to the state, the valve body can be opened quickly after the instruction is received.

Further, the control unit alternately performs heating of the thermo element by the heating element and stop of the heating, and adjusts at least one of a heating time for performing the heating and a heating stop time for stopping the heating. Thus, it is preferable to heat the thermo element so that the temperature of the thermo element rises while maintaining the valve closed state of the valve body. In this case, the length of the heating time or the heating stop time is adjusted based on parameters corresponding to the temperature of the cooling water downstream of the engine of the cooling water circuit and the heat generation amount of the engine.

In one aspect of the present invention, the control unit opens the valve body by heating the thermo element with the heating element based on the valve opening request of the valve body, and then stops heating the thermo element with the heating element. And alternately. And based on the parameter corresponding to the temperature of the cooling water downstream of the engine of the cooling water circuit and the heat generation amount of the engine, the heating time for heating the thermoelement by the heating element and the heating stop time for stopping the heating By adjusting the length of at least one of these, the opening degree after the opening operation of the valve body is adjusted.

For example, after opening the valve element by heating the thermo element with a heating element, it is conceivable to adjust the opening degree of the valve element so as to be fully open. Such opening degree adjustment is realized by alternately performing the above heating and stopping the heating. For this reason, when trying to hold the valve body in the fully open state, the heating of the thermo element by the heating element is excessively performed and the thermostat breaks down, and the heating of the thermo element by the heating element is insufficient. It is suppressed that the body cannot be held in the fully open state and the flow rate of the cooling water passing through the engine is insufficient.

Also, after opening the valve element by heating the thermo element with the heating element, the opening degree of the valve element can be adjusted to an intermediate opening degree between the closed valve and the fully opened valve. When opening the valve body that is in a closed state while the engine is warming up, if the opening degree of the valve body is adjusted to the intermediate opening degree as described above after the opening operation of the valve body, the valve body As a result of the opening operation, the flow rate of the cooling water when the cooling water passes through the engine is not excessively increased. For this reason, it is possible to prevent the temperature of the cooling water inside the engine from drastically decreasing due to the excessive increase in the flow rate of the cooling water, and to delay the engine warm-up. Therefore, it is possible to suppress an increase in fuel consumption.

In one aspect of the present invention, the controller controls the heating element when the temperature of the cooling water downstream from the engine of the cooling water circuit is a value at which the valve element can be opened by the thermo element. Prohibit heating of the thermo element. For this reason, when the temperature of the thermo element becomes a value that can open the valve body due to the transfer of heat from the cooling water of the cooling water circuit to the thermo element, It can be suppressed that heating is performed wastefully and that the temperature of the thermo element is excessively increased due to the heating and causes a malfunction of the thermostat.

The block diagram which showed typically the whole structure of the cooling device of the vehicle in this embodiment. (A) And (b) is the schematic which shows the structure of the thermostat of the said cooling device. The block diagram which shows the flow of the cooling water before the engine warming-up completion in the said cooling device. The block diagram which shows the flow of the cooling water before the engine warming-up completion in the said cooling device. The block diagram which shows the flow of the cooling water before the engine warming-up completion in the said cooling device. The block diagram which shows the flow of the cooling water after engine warm-up completion in the said cooling device. The graph which shows the change aspect of the opening degree of the thermostat with progress of time after the heating start of the thermo element by an element heater and after a heating stop start. The time chart which shows the change of the temperature of a thermo element with time progress from the starting start time of a vehicle. The time chart which shows the change of the temperature of a thermo element with time progress from the starting start time of a vehicle. The time chart which shows the change of the temperature of a thermo element with time progress from the starting start time of a vehicle. The time chart which shows the change of the temperature of a thermo element with the passage of time after a thermostat opens by valve-opening processing. The flowchart which shows the execution procedure of the pre-heat processing performed through the said cooling device, a valve opening process, and a valve closing process.

Hereinafter, an embodiment in which the present invention is embodied in a vehicle cooling device will be described with reference to FIGS.
FIG. 1 shows a configuration of a cooling water circuit of a vehicle cooling device of the present embodiment. This cooling device includes a first cooling water circuit that circulates cooling water through the inside of the engine 1 and a second cooling water that circulates cooling water through the exhaust heat recovery unit 2 without passing through the inside of the engine 1. Circuit. The cooling water in these cooling water circuits can be circulated by the same water pump 3. The water pump 3 is an electric pump, and the flow rate of cooling water discharged (hereinafter referred to as a discharge flow rate) is variable based on a command from the outside.

In the second cooling water circuit that circulates the cooling water without passing through the inside of the engine 1, the cooling water discharged from the water pump 3 passes through the exhaust heat recovery device 2, the heater core 6, and the temperature sensing valve 5, and the water pump. Return to 3. The exhaust heat recovery device 2 of the second cooling water circuit functions as a heat exchanger that performs heat exchange between the exhaust gas of the engine 1 and the cooling water of the second cooling water circuit, and heats the cooling water with the heat of the exhaust gas. The heater core 6 functions as a heat exchanger that warms the air blown into the passenger compartment through heat exchange between air and cooling water. The temperature sensing valve 5 positioned downstream of the heater core 6 is formed so as to always allow the coolant to flow after passing through the heater core 6.

On the other hand, the first cooling water circuit that circulates the cooling water through the inside of the engine 1 is branched into a main path that passes through the water pump 3, the engine 1, and the radiator 4 and a bypass path that bypasses the radiator 4. Yes. A thermostat 7 is provided at a branch portion between the main path and the bypass path in the first cooling water circuit. The radiator 4 provided in the main path of the first cooling water circuit is for radiating the heat of the cooling water in the first cooling water circuit to the outside air.

In the main path, the coolant discharged from the water pump 3 passes through the engine 1, the thermostat 7, the radiator 4, and the temperature sensing valve 5 and then returns to the water pump 3. The thermostat 7 is formed so as to always permit the flow of cooling water to the radiator 4 side after passing through the engine 1. The temperature sensing valve 5 is opened when the temperature of the cooling water after passing through the heater core 6 becomes a specified value (for example, 105 ° C.) or more, and allows the cooling water to circulate through the radiator 4. The temperature sensing valve 5 is closed when the temperature after passing through the heater core 6 is less than the specified value, and prohibits the circulation of the cooling water through the radiator 4. That is, in this vehicle cooling device, the radiator 4 radiates the heat of the cooling water that has passed through the inside of the engine 1 when the temperature of the cooling water flowing into the temperature sensing valve 5 exceeds a specified value. Activated.

Further, in the bypass path of the first cooling water circuit, the cooling water discharged from the water pump 3 returns to the water pump 3 through the engine 1, the thermostat 7, the heater core 6, and the temperature sensing valve 5. Yes. This bypass path joins the second cooling water circuit downstream of the exhaust heat recovery unit 2 and upstream of the heater core 6. The thermostat 7 prohibits the circulation of the cooling water through the bypass path of the first cooling water circuit according to the valve closing, and cools the cooling water of the first cooling water circuit and the second cooling water circuit according to the valve opening. Mix with water. The thermostat 7 is closed when the temperature of the cooling water in the first cooling water circuit is lower than a determination value (for example, 80 ° C.) for completion of warming up of the engine 1, and when the temperature of the cooling water is equal to or higher than the determination value. The valve opens upon receiving the heat of the cooling water. Further, the thermostat 7 can be forced to open from the closed state when the temperature of the cooling water in the first cooling water circuit is lower than the determination value and is in the closed state. Yes.

In the cooling device, the temperature of the cooling water passing through the temperature sensing valve 5 is less than the specified value, such as when the vehicle system is started (when the vehicle is started), the temperature sensing valve 5 is closed, and the thermostat 7 is closed. When is closed, the circulation of the cooling water through the engine 1 in the first cooling water circuit is stopped. Thus, the warm-up of the engine 1 is promoted by stopping the passage of the cooling water through the engine 1 in the first cooling water circuit. When the temperature of the cooling water including the inside of the engine 1 of the first cooling water circuit rises above the determination value due to the heat generated by the driving of the engine 1, the thermostat 7 is opened and the inside of the engine 1 in the first cooling water circuit is opened. The cooling water is allowed to pass through and the boiling of the cooling water inside the engine 1 is suppressed.

Next, the concrete structure and operation | movement aspect of the said thermostat 7 are demonstrated with reference to Fig.2 (a) and (b).
As shown in FIG. 2A, the thermostat 7 has a valve body 22 biased by a spring 21 in the closing direction (right direction in the figure), and resists the valve body 22 against the biasing force of the spring 21. And a thermo element 23 that is opened. The thermo element 23 protrudes or immerses the shaft 24 in association with thermal expansion or thermal contraction of the wax enclosed therein. The thermostat 7 opens or closes the valve element 22 by the protrusion or immersion of the shaft 24 and the biasing force of the spring 21.

Specifically, when the temperature of the cooling water around the thermo element 23 is low, the shaft 24 is in an immersive state due to heat shrinkage of the wax inside the thermo element 23. At this time, the valve body 22 of the thermostat 7 is closed by the biasing force of the spring 21. Since the valve body 22 is closed, the flow of the cooling water in the bypass path of the first cooling water circuit is prohibited, so that the passage of the cooling water inside the engine 1 is also prohibited. On the other hand, when the temperature of the cooling water around the thermostat 7 is high, the shaft 24 protrudes due to the thermal expansion of the wax inside the thermo element 23 as shown in FIG. Thereby, the valve body 22 of the thermostat 7 opens against the urging force of the spring 21 to be in the valve open state. At this time, since the circulation of the cooling water in the bypass path of the first cooling water circuit is permitted by opening the valve body 22, the passage of the cooling water inside the engine 1 is also permitted.

Further, in the thermostat 7, an element heater 25 is provided as a heating element for heating the thermo element 23 so as to forcibly open the valve element 22 in a closed state where the temperature of the surrounding cooling water is low. The element heater 25 heats the thermo element 23 by generating heat when energized. By heating the thermo element 23 by the element heater 25 in this way, even if the temperature of the cooling water around the thermo element 23 is low and the valve body 22 is in the closed state, the valve body 22 is forcibly opened. be able to.

Next, the electrical configuration of the vehicle cooling device in the present embodiment will be described with reference to FIG.
The vehicle cooling device includes an engine cooling control unit 11 that controls the forced opening operation of the thermostat 7 described above. The engine cooling control unit 11 when controlling the forced opening operation of the thermostat 7 controls the element heater 25 to cause the element heater 25 shown in FIG. 2 to heat the thermoelement 23. Functions as a part.

The engine cooling control unit 11 (FIG. 1) displays a CPU for performing various arithmetic processes related to the cooling control of the engine 1, a ROM in which a control program and data are stored, a CPU calculation result, a sensor detection result, and the like. The electronic control unit includes a RAM that temporarily stores data and an I / O that controls input / output of signals to / from the outside. The engine cooling control unit 11 includes a detection signal from the water temperature sensor 12 for detecting the cooling water temperature thw1 at the outlet of the engine 1 in the first cooling circuit, and a rotation speed sensor 15 for detecting the engine rotation speed. A detection signal and a detection signal from the air flow meter 16 that detects the intake air amount of the engine 1 are input.

Further, the vehicle is provided with an air conditioning control unit 13 that controls air conditioning in the passenger compartment, specifically, heating of air in the heater core 6 and control of blowing of the heated air into the passenger compartment. As with the engine cooling control unit 11, the air conditioning control unit 13 is also configured as an electronic control unit including a CPU, ROM, RAM, and I / O. The air conditioning control unit 13 and the engine cooling control unit 11 are connected to each other through an in-vehicle network (CAN), and share necessary information through mutual communication.

3 and 4 show the flow of the cooling water in the cooling device after the start of the engine 1 from the cold state and before the warm-up of the engine 1 is completed. Normally, at this time, both the temperature sensing valve 5 and the thermostat 7 are closed. That is, the temperature sensing valve 5 is closed based on the fact that the temperature of the cooling water circulating in the second cooling water circuit is less than the specified value, and the cooling water temperature thw1 at the outlet of the engine 1 in the first cooling water circuit is The thermostat 7 is closed based on being less than the determination value. Therefore, at this time, as shown in FIG. 3, the circulation of the cooling water in the first cooling water circuit is prohibited, and the cooling water is circulated only in the second cooling water circuit. When the circulation of the cooling water in the first cooling water circuit is prohibited in this way, the cooling water stays in the engine 1 and the temperature of the cooling water is accelerated by the heat generation of the engine 1, so that the engine 1 is warmed up. Is expedited. Further, the cooling water circulating in the second cooling water circuit is heated by the heat recovered from the exhaust in the exhaust heat recovery unit 2. Here, when there is a heating request in the passenger compartment, the air blown into the passenger compartment is warmed by the heat recovered from the exhaust in the exhaust heat recovery device 2.

By the way, when both the temperature sensing valve 5 and the thermostat 7 are closed and circulation of the cooling water in the first cooling water circuit is prohibited, the following conditions [1] and [2] In order to mix the cooling water of the first cooling water circuit into the second cooling water circuit, the thermoelement 23 is heated by the element heater 25 (FIG. 2A), and the thermostat 7 is opened. [1] When the thermostat 7 is closed, based on the cooling water temperature thw1 and the engine operating state, the temperature of the cooling water staying in the engine 1 (cylinder head or the like) is increased to a value that may cause boiling due to heat generated by the engine 1. When it is predicted. [2] When it becomes necessary to heat the passenger compartment when the thermostat 7 is closed, and accordingly the temperature of the cooling water passing through the heater core 6 needs to be raised quickly.

Therefore, as shown in FIG. 3, when both the temperature sensing valve 5 and the thermostat 7 are closed and the circulation of the cooling water in the first cooling water circuit is prohibited, the above [1] or [2] When a situation arises, a valve opening request (valve opening instruction) of the thermostat 7 is made, and the thermostat 7 is opened as described above based on the request. Thereby, the cooling water upstream of the exhaust heat recovery device 2 in the second cooling water circuit flows into the first cooling water circuit, and the cooling water in the first cooling water circuit passes through the engine 1 and the thermostat 7 by the cooling water. It is pushed out of the heater core 6 upstream of the second coolant circuit. In this way, the cooling water of the first cooling water circuit flows to the upstream side of the heater core 6 of the second cooling water circuit and is mixed with the cooling water of the same circuit, and the cooling in the first cooling water circuit as shown in FIG. 4 or FIG. Water circulation takes place. 4 shows the flow of the cooling water in the cooling device when the thermostat 7 is fully opened, and FIG. 5 shows the cooling device when the thermostat 7 is adjusted to an intermediate opening degree between the valve closing and the full opening. The flow of the cooling water at is shown.

In the situation [1], when the thermostat 7 is opened, the cooling water of the first cooling water circuit flows into the second cooling water circuit and is mixed with the cooling water of the same circuit, and stays in the engine 1 accordingly. The high temperature cooling water that has been discharged is flowed out of the engine 1. As a result, it is possible to prevent the cooling water staying in the engine 1 from rising due to the heat generated by the engine 1 and boiling. Further, when the thermostat 7 is opened in the situation [2], the cooling water of the first cooling water circuit flows into the second cooling water circuit and is mixed with the cooling water of the same circuit as described above. The high-temperature cooling water staying in the engine 1 passes through the heater core 6 of the 2-cooling water circuit. As a result, the air blown into the vehicle interior can be effectively heated with the cooling water of the heater core 6, and as a result, the heating requirement in the vehicle interior can be satisfied.

FIG. 6 shows the flow of cooling water in the cooling device after the warm-up of the engine 1 is completed. At this time, the temperature sensing valve 5 is opened based on the temperature of the cooling water passing through the temperature sensing valve 5 being equal to or higher than the specified value, and the temperature of the cooling water passing through the thermostat 7 is equal to or higher than the determination value. On the basis of something, the thermostat 7 is opened. As a result, the cooling water is circulated in the second cooling water circuit, and the cooling water is circulated through the main path of the first cooling water circuit.

Next, inconveniences related to the opening operation of the thermostat 7 and countermeasures will be described with reference to FIGS.
In the above-mentioned situations [1] and [2], the thermostat 23 (valve element 22) is opened by heating the thermoelement 23 by the element heater 25 (FIG. 2), so that it stays in the engine 1. This makes it possible to respond to boiling of cooling water and heating requirements in the passenger compartment. However, when the temperature of the cooling water around the thermo-element 23 is low, even if the thermo-element 23 is heated by the element heater 25, the temperature of the thermo-element 23 rises by that and it is long until the valve element is completely opened. take time.

Here, how the opening degree of the thermostat 7 changes with time after the start of heating of the thermo element 23 by the element heater 25 and after the start of heating stop is shown for each cooling water temperature thw1 in FIG. As can be seen from the figure, as the cooling water temperature thw1 at the start of heating decreases from “65 ° C.” to “0 ° C.”, the time required from the start of heating until the thermostat 7 opens becomes longer. Further, as the cooling water temperature thw1 at the time when the heating start is stopped decreases from “65 ° C.” to “0 ° C.”, the time required from the start of the heating stop until the thermostat 7 is closed becomes longer.

Thus, the responsiveness is poor with respect to the opening of the thermostat 7 due to the heating of the thermoelement 23 by the element heater 25 (FIG. 2) and the closing of the thermostat 7 due to the heat radiation from the thermoelement 23. For this reason, even when the thermo-element 23 is heated by the element heater 25 based on the valve opening request of the thermostat 7 in the situations [1] and [2], the following inconvenience may occur. That is, after the thermostat 7 is requested to open, before the thermostat 7 is actually opened and water is introduced into the engine 1, the cooling water in the engine 1 boils, There may be a delay in raising the temperature of the cooling water passing through the heater core 6 in response to a heating request (corresponding to the valve opening request).

In the present embodiment, as a countermeasure against such an inconvenience, when the thermostat 7 (valve element 22) is closed through the engine cooling control unit 11, the element heater 25 increases the temperature of the thermo element 23 while maintaining the closed state. The thermo element 23 is heated.

In this case, when the temperature of the cooling water in the first cooling water circuit (cooling water temperature thw1) and the temperature of the thermo element 23 are low and the valve body 22 of the thermostat 7 is closed, the element heater 25 is as described above. The thermo element 23 is heated by the above. Therefore, when the thermoelement 23 is heated by the element heater 25 to open the valve body 22 based on the valve opening request (valve opening instruction) of the valve body 22 of the thermostat 7, the temperature of the thermoelement 23 is increased. The valve body 22 is quickly raised to a value at which the valve body 22 can be opened, whereby the valve body 22 is opened. Accordingly, when the valve element 22 of the thermostat 7 in the valve-closed state is opened by heating the thermoelement 23 with the element heater 25, the valve element 22 can be opened quickly after receiving the instruction. .

FIGS. 8 and 9 are time charts showing changes in the temperature of the thermo element 23 as time elapses from the start of the vehicle.
In FIG. 8, when the thermoelement 23 is not heated by the element heater 25 during the period from the start of vehicle start (T1) to the time when the thermostat 7 is requested to open (T2), the thermoelement 23 during that period The temperature remains at a low value. When the valve opening of the thermostat 7 is requested in this state (T2), heating of the thermo element 23 by the element heater 25 is started from that time, but the temperature of the thermo element 23 opens the thermostat 7 (valve element 22). It takes a long time (T2 to T3) to rise to the value BO1 to be valved.

On the other hand, in the present embodiment, as shown in FIG. 9, the thermostat 7 is closed during the period from the start of the vehicle start (T1) to the time when the thermostat 7 is opened (T2). At the time of valve operation, the thermoelement 23 is heated by the element heater 25 so that the temperature of the thermoelement 23 rises while maintaining the closed state. Heating of the thermo-element 23 during the period from the start of the vehicle start to the time when the valve-opening request is made for the first time, that is, the thermo-element in a state in which there is no history of the valve-opening request after the vehicle starts. The heating of 23 will be implemented as a pre-heat treatment. In the pre-heat treatment, heating of the thermo element 23 by the element heater 25 and the stop of the heating are alternately performed, and at least one of the heating time t1 for performing the heating and the heating stop time t2 for stopping the heating is long. By adjusting the height, the temperature of the thermo element 23 is raised while the valve body 22 is kept closed.

In this embodiment, as described above, both the heating time t1 and the heating stop time t2 have the lengths of the engine so as to increase the temperature of the thermo element 23 while maintaining the valve closed state of the valve element 22. It is adjusted based on a parameter related to the cooling water temperature thw1 at one outlet and the heat generation amount of the engine 1. Accordingly, the heating time t1 is lengthened and the heating stop time t2 is shortened as the cooling water temperature thw1 is lowered. Conversely, the heating time t1 is shortened and the heating stop time t2 is lengthened as the cooling water temperature thw1 is raised. Further, the heating time t1 is lengthened and the heating stop time t2 is shortened as the parameter becomes a value on the heat generation amount decrease side of the engine 1, and conversely, the heating time is increased as the parameter becomes a value on the heat generation amount increase side of the engine 1. While t1 is shortened, the heating stop time t2 is lengthened. Examples of the parameters include the engine rotational speed detected based on the rotational speed sensor 15 and the engine load calculated as the amount of air taken into the engine 1 per cycle of the engine 1. This engine load is calculated based on the engine rotation speed detected by the rotation speed sensor 15 and the intake air amount of the engine 1 detected by the air flow meter 16.

By adjusting the length of the heating time t1 and the heating stop time t2 in the pre-heat treatment, the initial heating time t1 after the start of the vehicle starts becomes relatively long as shown in FIG. 9, and during the heating time t1 Further, the temperature of the thermoelement 23 rises to a value slightly lower than the value BO1 for opening the valve body 22. After that, by repeating the heating stop time t2 and the heating time t1, the temperature of the thermo element 23 falls or rises in the range not exceeding the value BO1 for opening the valve body 22 and in the vicinity of the value BO1. . Under this state, when there is a request to open the thermostat 7 based on the above conditions [1] and [2] (T2), the valve element 22 of the thermostat 7 is opened by heating the thermoelement 23 with the element heater 25. A valve opening process for causing the valve to be valved is executed. When this valve opening process is executed, the temperature of the thermo-element 23 quickly rises to the value BO1 or higher, and the valve element 22 is opened when the temperature reaches the value BO1 (T4). Therefore, when the valve element 22 of the thermostat 7 in the valve-closed state is opened by heating the thermoelement 23 with the element heater 25, the valve element 22 is opened immediately after the request (instruction) is received. be able to.

The valve opening process is performed in detail as follows. That is, based on a valve opening request of the thermostat 7, the element heater 25 heats the thermo element 23 to open the valve element 22 (thermostat 7). Thereafter, the heating of the thermoelement 23 by the element heater 25 and the stop of the heating are alternately performed, and the length of at least one of the heating time t3 for performing the heating and the heating stop time t4 for stopping the heating is adjusted. Thereby, the opening degree adjustment after the valve body 22 (thermostat 7) is opened is performed.

In this embodiment, in order to adjust the opening after the opening operation of the valve body 22, the lengths of both the heating time t3 and the heating stop time t4 are the cooling water temperature thw1 at the outlet of the engine 1 and the engine 1 It is adjusted based on the above parameters related to the amount of heat generated. As a result, the lower the cooling water temperature thw1, the longer the heating time t3 and the shorter the heating stop time t4. Conversely, the higher the cooling water temperature thw1, the shorter the heating time t3 and the longer the heating stop time t4. Further, the heating time t3 is lengthened and the heating stop time t4 is shortened as the parameter becomes a value on the heat generation amount decrease side of the engine 1, and conversely, the heating time is increased as the parameter becomes a value on the heat generation amount increase side of the engine 1. As t3 is shortened, the heating stop time t4 is lengthened.

Here, it is conceivable to adjust the opening degree of the valve element 22 after the opening operation so that the valve element 22 is fully opened. In this case, through the adjustment of the heating time t3 and the heating stop time t4 in the valve opening process, the first heating time t3 after the opening request of the thermostat 7 becomes relatively long as shown in FIG. During the heating time t3, the temperature of the thermo element 23 rises to a value slightly lower than the value BO2 that fully opens the valve element 22. Thereafter, by repeating the heating stop time t4 and the heating time t3, the temperature of the thermo-element 23 decreases or rises in a range not exceeding the value BO2 for opening the valve body 22 and in the vicinity of the value BO2. . Thereby, the opening degree of the valve body 22 after the valve opening request | requirement of the thermostat 7 is adjusted to the state of substantially full opening.

Such adjustment to the fully open state of the valve body 22 includes heating the thermoelement 23 by the element heater 25 at the heating time t3 and stopping heating of the thermoelement 23 by the element heater 25 at the heating stop time t4. It is realized by performing alternately. For this reason, when trying to hold the valve element 22 in the fully opened state, the element heater 25 excessively heats the thermo element 23, and the temperature of the thermo element 23 is indicated by a two-dot chain line L1 in FIG. The value BO2 will not rise significantly beyond. Therefore, the thermostat 7 is prevented from being damaged due to an excessive temperature rise of the thermo element 23. Further, when the valve element 22 is to be held in the fully open state, the thermo element 23 is not sufficiently heated by the thermo element 23, and the temperature of the thermo element 23 decreases as indicated by a two-dot chain line L2 in FIG. I don't want to go. Therefore, it is also possible to suppress a shortage of the flow rate of the cooling water passing through the engine 1 without being able to hold the valve element 22 in the fully open state due to an excessive temperature drop of the thermo element 23.

In the above valve opening process, the opening after the opening operation of the valve body 22 in the closed state may be adjusted to an intermediate opening between the valve closing and the full opening. In this case, through the adjustment of the length of the heating time t3 and the heating stop time t4 in the valve opening process, for example, the first heating time t3 after the valve opening request of the thermostat 7 is shorter than the state shown in FIG. Adjustments are made as shown in FIG. Then, during the heating time t3, the temperature of the thermoelement 23 rises to a value that causes the valve element 22 to have the intermediate opening. Thereafter, by repeating the heating stop time t4 and the heating time t3, the temperature of the thermo element 23 decreases or increases in the vicinity of a value that causes the valve element 22 to have the intermediate opening degree. Thereby, the opening degree of the valve body 22 after the valve opening request | requirement of the thermostat 7 is adjusted so that it may become the said intermediate opening degree.

When the valve body 22 in the closed state is opened based on the valve opening request of the thermostat 7 while the engine 1 is warming up, the opening degree of the valve body 22 is set as described above after the valve body 22 is opened. If the opening is adjusted to an intermediate opening, the flow rate of the cooling water when the cooling water passes through the engine 1 by the opening operation of the valve body 22 does not excessively increase. For this reason, it can suppress that the temperature of the cooling water inside the engine 1 suddenly decreases due to an excessive increase in the flow rate of the cooling water and delays the warm-up of the engine 1, and the warming is increased by the delay. It can suppress that the fuel consumption for a machine increases.

FIG. 11 is a time chart showing a change in temperature of the thermo element 23 over time after the thermostat 7 is opened by the valve opening process.
When the conditions [1] and [2] no longer occur in a state where the thermostat 7 is opened by the valve opening process, a valve closing request (valve closing instruction) of the thermostat 7 is made (T5). When the valve closing request is made in this way, a valve closing process for closing the valve body 22 of the thermostat 7 by controlling the heating of the thermo element 23 by the element heater 25 is executed.

The valve closing process is performed as follows in detail. That is, based on the valve closing request of the thermostat 7, heating of the thermo element 23 by the element heater 25 is stopped and the valve body 22 (thermostat 7) is closed (T6). Thereafter, heating of the thermo-element 23 by the element heater 25 and stop of the heating are alternately performed, and the length of at least one of the heating time t5 for performing the heating and the heating stop time t6 for stopping the heating is adjusted. Thus, the temperature of the thermo element 23 is maintained at a value lower than the value BO1 and in the vicinity of the same value BO1 while maintaining the valve closed state of the thermostat 7. In other words, the thermoelement 23 is heated by the element heater 25 so as to raise the temperature of the thermoelement 23 as much as possible while maintaining the valve closed state of the thermostat 7. Note that heating of the thermo element 23 by the element heater 25 in such valve closing processing is performed in a state where there is a history of valve opening requests after the start of the vehicle.

In this embodiment, when adjusting the opening after the valve body 22 is closed as the valve closing process, the length of both the heating time t5 and the heating stop time t6 is the cooling water temperature thw1 at the engine 1 outlet. , And the above parameters related to the heat generation amount of the engine 1 are adjusted. As a result, the lower the coolant temperature thw1, the longer the heating time t5 and the shorter the heating stop time t6. Conversely, the higher the coolant temperature thw1, the shorter the heating time t5 and the longer the heating stop time t6. Further, the heating time t5 is lengthened and the heating stop time t6 is shortened as the parameter becomes a value on the heat generation amount decrease side of the engine 1, and conversely, the heating time is increased as the parameter becomes a value on the heat generation amount increase side of the engine 1. While t5 is shortened, the heating stop time t6 is lengthened.

Next, the execution procedure of the preheat treatment, the valve opening process, and the valve closing process described above will be described with reference to the flowchart of FIG. 12 showing an element heater control routine for heating and stopping the thermoelement 23 by the element heater 25. To do. The element heater control routine is periodically executed through the engine cooling control unit 11 by, for example, a time interruption every predetermined time.

In this routine, first, it is determined whether or not the coolant temperature thw1 at the outlet of the engine 1 is less than the determination value (S101). If the determination is negative, the temperature of the thermo element 23 that receives heat from the cooling water in the first cooling water circuit is equal to or higher than the value BO1 that opens the valve body 22, so Heating is prohibited (S108). On the other hand, if the determination in S101 is affirmative, the temperature of the thermoelement 23 during the stop of heating of the thermoelement 23 by the element heater 25 becomes less than the value BO1 for opening the valve element 22, and therefore the element heater 25 The processing (S102 to S107) for heating and stopping the heating of the thermoelement 23 is performed.

In this series of processes, it is first determined whether or not there is a history of valve opening requests for the thermostat 7 after the vehicle is started (S102). If the determination is negative, the valve opening of the thermostat 7 and the opening of the valve element 22 by heating of the thermo element 23 by the element heater 25 based on the request after the start of the vehicle have never been made. In this case, pre-heat treatment is performed (S103), and then the process proceeds to S104. In the pre-heat treatment, heating of the thermo element 23 by the element heater 25 and stop of the heating are alternately performed, and through adjustment of the length of the heating time t1 for performing the heating and the heating stop time t2 for stopping the heating, The temperature of the thermo element 23 is raised while maintaining the valve body 22 in the closed state. More specifically, the temperature of the thermo element 23 is adjusted so as to be a value in the range not exceeding the value BO1 for opening the valve body 22 and in the vicinity of the value BO1.

On the other hand, if the determination in S102 is affirmative, the valve body 22 is opened at least once by the opening of the thermostat 7 and the heating of the thermoelement 23 by the element heater 25 based on the opening request after starting the vehicle. In this case as well, the process proceeds to S104. In the process of S104, it is determined whether or not there is a request for opening the thermostat 7 (S104). If the determination is affirmative, the valve opening process is executed (S105). Regarding this valve opening process, a state in which the temperature of the thermo-element 23 is adjusted within the range not exceeding the value BO1 for opening the valve element 22 and in the vicinity of the value BO1 by the pre-heat treatment or the valve closing process. Is executed. In the valve opening process, first, the thermoelement 23 is heated by the element heater 25 to open the valve element 22 (thermostat 7). Thereafter, the heating of the thermo element 23 by the element heater 25 and the stop of the heating are alternately performed, and the valve element 22 is adjusted through length adjustment between the heating time t3 for performing the heating and the heating stop time t4 for stopping the heating. The opening is adjusted after the valve is opened. More specifically, the temperature of the thermo element 23 is adjusted to a value within the range from the value BO1 to the value BO2.

If a negative determination is made in the process of S104, it is determined whether or not there is a valve closing request for the thermostat 7 (S106). If an affirmative determination is made here, the valve closing process is executed (S107). This valve closing process is executed in a state where the temperature of the thermo-element 23 is adjusted to a value within the range from the value BO1 to the value BO2 by the valve opening process. In the valve closing process, first, heating of the thermo element 23 by the element heater 25 is stopped, and the valve element 22 (thermostat 7) is closed. Thereafter, the heating of the thermo element 23 by the element heater 25 and the stop of the heating are alternately performed, and the thermostat 7 is adjusted by adjusting the length of the heating time t5 for performing the heating and the heating stop time t6 for stopping the heating. While maintaining the valve closed state, the temperature of the thermo-element 23 is maintained at a value lower than the value BO1 and in the vicinity of the same value BO1. In other words, the thermoelement 23 is heated by the element heater 25 so as to raise the temperature of the thermoelement 23 as much as possible while maintaining the valve closed state of the thermostat 7.

According to the embodiment described in detail above, the following effects can be obtained.
(1) When the cooling water temperature thw1 and the temperature of the thermo element 23 are low and the valve element 22 of the thermostat 7 is closed, the temperature of the thermo element 23 increases while maintaining the valve element 22 closed. Thus, the thermoelement 23 is heated by the element heater 25. That is, when the valve element 22 is closed after the start of the vehicle, or when the valve element 22 is requested to open in the open state after the start of the vehicle, the valve element 22 is closed based on the request. At this time, the thermo element 23 is heated in a state in which the valve body 22 is kept closed.

Regarding heating of the thermo element 23, heating of the thermo element 23 by the element heater 25 and stopping of the heating are alternately performed, and heating times t1 and t5 for performing the heating and heating stop times t2 and t6 for stopping the heating are performed. It is realized by adjusting the length. The lengths of the heating times t1 and t5 and the heating stop times t2 and t6 are adjusted based on the cooling water temperature thw1 at the outlet of the engine 1 and a parameter corresponding to the heat generation amount of the engine 1.

Then, when the valve body 22 is closed after the start of the vehicle or when the valve body 22 is requested to open in the open state after the start of the vehicle, the valve body 22 is closed based on the request. When a valve opening request (valve opening instruction) for the valve body 22 is made, the thermoelement 23 is heated by the element heater 25 for opening the valve body 22. As a result, the temperature of the thermo element 23 quickly rises to the value BO1 at which the valve body 22 can be opened, thereby opening the valve body 22. Therefore, when there is a valve opening request (opening instruction) for the valve body 22 that is in the closed state after the start of the vehicle, the valve body 22 that is in the open state is further based on the valve closing request for the valve body 22. When there is a valve opening request (opening instruction) of the valve body 22 after shifting to the valve closing state, the valve body 22 can be opened quickly after the instruction is received.

(2) When the valve element 22 is opened by heating the thermoelement 23 by the element heater 25 based on the valve opening request of the valve element 22 in the thermostat 7, the valve element 22 is opened by the heating, and thereafter Further, heating of the thermo element 23 by the element heater 25 and stopping of the heating are alternately performed. And based on the parameter corresponding to the cooling water temperature thw1 at the outlet of the engine 1 and the heat generation amount of the engine 1, the length of the heating time t3 for heating the thermoelement 23 by the element heater 25 and the heating stop time t4 for stopping the heating By adjusting the opening degree, the opening degree after the opening operation of the valve body 22 is adjusted.

For example, after opening the valve element 22 by heating the thermo element 23 with the element heater 25, it is conceivable to adjust the opening degree of the valve element 22 so that the valve element 22 is fully opened. Such opening degree adjustment is realized by alternately performing the above heating and stopping the heating. For this reason, when trying to hold the valve element 22 in the fully open state, the element heater 25 excessively heats the thermoelement 23 and the thermostat 7 fails, and the element heater 25 causes the thermoelement 23 to fail. It is suppressed that heating is insufficient and the valve body 22 cannot be held in the fully open state, leading to an insufficient flow rate of the cooling water passing through the engine 1.

Further, after the opening operation of the valve element 22 by heating the thermo element 23 with the element heater 25, the opening degree of the valve element 22 may be adjusted to an intermediate opening degree between the valve closing and the full opening. When the valve element 22 that is in the closed state is opened while the engine 1 is warming up, the opening degree of the valve element 22 is adjusted to the intermediate opening degree as described above after the opening operation of the valve element 22. The flow rate of the cooling water when the cooling water passes through the engine 1 by the opening operation of the valve body 22 is not excessively increased. For this reason, it can suppress that the temperature of the cooling water inside the engine 1 suddenly decreases due to an excessive increase in the flow rate of the cooling water and delays the warm-up of the engine 1, and the warming is increased by the delay. It can suppress that the fuel consumption for a machine increases.

(3) When the cooling water temperature thw1 at the outlet of the engine 1 is equal to or higher than the determination value and the temperature of the thermo element 23 that receives heat from the cooling water in the first cooling water circuit is equal to or higher than the value BO1, the thermo element by the element heater 25 In a state where the heating of 23 is stopped, the valve element 22 is opened by the thermo element 23. At this time, heating of the thermo element 23 by the element heater 25 is prohibited. Therefore, when the temperature of the thermoelement 23 is equal to or higher than the value BO1 due to the transfer of heat from the coolant in the first coolant circuit to the thermoelement 23, the element heater 25 heats the thermoelement 23 wastefully. It is possible to suppress the temperature of the thermoelement 23 from being excessively increased due to the heating and the same heating and causing the thermostat 7 to fail.

In addition, the said embodiment can also be changed as follows, for example.
The vehicle to which the present invention is applied may be either a vehicle that runs only by the engine 1 or a hybrid vehicle that runs by at least one of the engine 1 and the motor. Note that, when the vehicle system is started in the present embodiment (when the vehicle is started), power is supplied to various devices necessary for traveling the vehicle, and the engine can be started and the motor of the vehicle can be operated. It is a state of being.

-An EGR cooler may be provided on the upstream side of the heater core 6 in the second cooling water circuit. Such an EGR cooler is for cooling the EGR gas with the cooling water of the second cooling water circuit, and during the cooling, heat exchange between the heat of the exhaust gas of the engine 1 and the cooling water of the second cooling water circuit is performed. It functions as a heat exchanger that heats the cooling water with the heat of the exhaust gas.

DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Waste heat recovery device, 3 ... Water pump, 4 ... Radiator, 5 ... Temperature sensing valve, 6 ... Heater core, 7 ... Thermostat, 11 ... Engine cooling control part, 12 ... Water temperature sensor, 13 ... Air conditioning control , 15 ... rotational speed sensor, 16 ... air flow meter, 21 ... spring, 22 ... valve body, 23 ... thermo element, 24 ... shaft, 25 ... element heater.

Claims

A cooling water circuit that circulates cooling water through the inside of the engine by driving a pump, and a thermostat provided on the downstream side of the engine in the cooling water circuit, the thermostat is a valve body when the temperature of the cooling water is low Is closed to prevent the coolant from passing through the engine, and when the temperature of the coolant is high, the valve element is opened by a thermo element that receives heat from the coolant to cool the engine. In a vehicle cooling device that allows water to pass through,
A heating element capable of heating the thermo element to open the valve body;
A control unit that causes the heating element to heat the thermo element so that the temperature of the thermo element rises while maintaining the closed state when the valve body is closed;
A vehicle cooling device comprising:
The controller performs heating of the thermo element in a state in which the valve body is kept closed when the valve body is closed after the start of the vehicle, and the valve after the start of the vehicle is started. The vehicle cooling device according to claim 1, which is also performed when a valve closing request is made while the body is open.
The control unit alternately performs heating of the thermo element by the heating element and stop of the heating, and parameters corresponding to the temperature of cooling water downstream from the engine of the cooling water circuit and the amount of heat generated by the engine. The temperature of the thermo element rises while maintaining the valve closed state of the valve body by adjusting the length of at least one of the heating time for performing the heating and the heating stop time for stopping the heating based on The vehicle cooling device according to claim 1, wherein the thermo element is heated.
The control unit opens the valve body by heating the thermo element with the heating element based on a valve opening request of the valve body, and then stops heating the thermo element with the heating element. And the control unit stops the heating for the heating time and the heating based on the parameters corresponding to the temperature of the cooling water downstream of the engine of the cooling water circuit and the heat generation amount of the engine. The vehicle cooling device according to claim 1, wherein an opening degree adjustment after the opening operation of the valve body is performed by adjusting at least one length of the heating stop time.
When the temperature of the cooling water downstream from the engine of the cooling water circuit is a value at which the valve element can be opened by the thermo element, the control unit is configured to use the thermo element by the heating element. The vehicle cooling device according to claim 1, wherein heating of the vehicle is prohibited.