JP2011099400A - Cooling device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling device for a vehicle, which accurately adjusts the opening of a valve mixing the cooling water in a first cooling water circuit and the cooling water in a second cooling water circuit to an appropriate value according to the actual discharge flow rate of cooling water from a pump with good response in a simple structure. <P>SOLUTION: A relief valve 7 is used as the valve mixing the cooling water of a bypass route in the first cooling water circuit with the cooling water in the second cooling water circuit. The relief valve 7 includes a valve element 9 energized to a valve close direction by the elastic force of a spring 8 and a receiving force based on the pressure difference between the pressure on its own upstream side and the pressure on a downstream side in a valve open direction. Thus, the relief valve 7 which is closed will be opened by increasing the discharge flow rate of the water pump 3 so as to keep the force acting on the valve element 9 in the valve open direction based on the pressure difference between the pressure on the upstream side of the relief valve 7 and the pressure on the downstream side larger than the force acting on the valve element 9 in the valve close direction by elastic force of the spring 8. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vehicle cooling device.

  Conventionally, a first cooling water circuit that circulates cooling water through the engine and a second cooling water circuit that circulates cooling water without passing through the engine are provided, and the cooling water is independently supplied to each circuit. A vehicle cooling device that can be circulated has been proposed. In such a cooling device, the first cooling water circuit is used for cooling the engine, and the second cooling water circuit is used for recovering exhaust heat of the engine and heating the vehicle interior as disclosed in Patent Document 1, for example.

  FIG. 15 shows the configuration of the cooling device of Patent Document 1. The cooling water circulating in the first cooling water circuit in the apparatus is discharged from the first water pump 52, passes through the engine 50, is radiated by the radiator 53 downstream of the engine 50, and then passes through the thermostat 54. Returning to the first water pump 52. The thermostat 54 of the first cooling water circuit operates in response to the temperature of the incoming cooling water and prohibits or permits the passage of the cooling water radiator 53. In addition, the cooling water circulating in the second cooling water circuit is discharged from the second water pump 55, and then the heater core 56 that heats the air blown into the vehicle interior with the heat of the cooling water and the exhaust gas of the engine 50 The heat returns to the second water pump 55 again through the exhaust heat recovery device 51 for recovering the heat of the exhaust gas by heat exchange between them and the three-way valve 57 for controlling the flow of the cooling water. The second cooling water circuit is provided with a water temperature sensor 60 that detects the temperature of the cooling water downstream of the second water pump 55. The first cooling water circuit and the second cooling water circuit are a water channel 58 that connects the downstream side of the engine 50 and the three-way valve 57, and a water channel 59 that connects the downstream side of the exhaust heat recovery unit 51 and the thermostat 54. And connected to each other.

  In such a conventional vehicle cooling device, the thermostat 54 is closed when the temperature of the incoming cooling water is low, and the flow of the cooling water through the thermostat 54 is blocked. The three-way valve 57 is controlled according to the temperature detected by the water temperature sensor 60. When the detected temperature is low, the exhaust heat recovery unit 51 and the second water pump 55 are connected, and when the detected temperature is high, the engine 50 and the second water pump 55 are connected. Further, the first water pump 52 is controlled according to the temperature detected by the water temperature sensor 60, and stops its operation when the detected temperature is low.

  In FIG. 16, the flow of the cooling water when the temperature of the cooling water downstream of the second water pump 55 detected by the water temperature sensor 60 is low is indicated by an arrow. At this time, the thermostat 54 is closed, and the three-way valve 57 operates to connect the exhaust heat recovery device 51 and the second water pump 55. Therefore, at this time, the first cooling water circuit and the second cooling water circuit are separated. At this time, the first water pump 52 is stopped and only the second water pump 55 is operating. Therefore, in the vehicle cooling device at this time, the cooling water is circulated only by the second cooling water circuit. That is, the cooling water at this time flows from the second water pump 55 through the heater core 56 and the exhaust heat recovery device 51 to return to the second water pump 55 again. On the other hand, in the engine 50 at this time, the cooling water is not circulated and is kept in the engine 50, so that the temperature of the cooling water is increased, and hence the engine 50 is warmed up. Further, if the vehicle interior is heated at this time, the cooling water heated by the heat of the exhaust gas in the exhaust heat recovery device 51 is sent to the heater core 56. Therefore, the exhaust gas recovered by the exhaust heat recovery device 51 The air can be warmed by the heat.

  On the other hand, in FIG. 17, the flow of the cooling water when the temperature of the cooling water downstream of the second water pump 55 detected by the water temperature sensor 60 is high is indicated by an arrow. At this time, the thermostat 54 is opened, and the three-way valve 57 operates to connect the engine 50 and the second water pump 55. At this time, both the first water pump 52 and the second water pump 55 are operating. Therefore, in the vehicle cooling device at this time, the following first circulation loop and second circulation loop are formed as two cooling water circulation loops. The first circulation loop is a loop that returns from the first water pump 52 to the first water pump 52 through the inside of the engine 50, the radiator 53, and the thermostat 54. The second circulation loop is diverted from the first circulation loop after passing through the engine 50, passes through the second water pump 55, the heater core 56, and the exhaust heat recovery device 51, and then is connected to the second circulation loop in the thermostat 54. It is a loop that joins again. At this time, the cooling water of the first cooling water circuit and the cooling water of the second cooling water circuit are mixed. Therefore, if the cooling water of the second cooling water circuit before mixing is sufficiently heated by the heat of exhaust gas in the exhaust heat recovery device 51, the temperature of the cooling water flowing into the engine 50 can be increased by the mixing. As a result, warm-up of the engine 50 can be promoted.

  By the way, in the conventional vehicle cooling device, the cooling water inside the engine 50 in the first cooling water circuit is heated by the heat generation of the engine 50 immediately after the start of the engine 50 starts. For this reason, before the temperature of the cooling water detected by the water temperature sensor 60 is increased and mixing of the cooling water is performed, the temperature of the cooling water in the engine 50 in the first cooling water circuit is the cooling water in the second cooling water circuit. The temperature may be higher than

  Considering this, in the situation shown in the following [1] and [2], the temperature of the cooling water detected by the water temperature sensor 60 is low, and the three-way valve 57 is connected to the first cooling water circuit and the second cooling water. Even when operating to shut off the water circuit, it is conceivable to operate the three-way valve 57 so that the cooling water of the cooling water circuit is mixed. [1] When the cooling water staying in the engine 50 is heated to a value that may cause boiling due to heat generated by the engine 50 as the first cooling water circuit and the second cooling water circuit are disconnected by the three-way valve 57. . [2] When the first cooling water circuit and the second cooling water circuit are shut off by the three-way valve 57, it becomes necessary to heat the vehicle interior, and accordingly, the temperature of the cooling water passing through the heater core 56 needs to be increased quickly. When there is.

  When the three-way valve 57 operates to mix the cooling water of the first cooling water circuit with the cooling water of the second cooling water circuit in the situation of [1] above, the cooling water of the first cooling water circuit is second cooled. In order to flow into the water circuit, the high-temperature cooling water staying in the engine 50 is flowed out of the engine 50. As a result, it is possible to prevent the cooling water staying in the engine 50 from rising due to the heat generated by the engine 50 and boiling. In the situation [2], when the three-way valve 57 operates to mix the cooling water in the first cooling water circuit with the cooling water in the second cooling water circuit, the cooling water in the first cooling water circuit becomes the first. In order to flow into the 2-cooling water circuit, the high-temperature cooling water staying in the engine 50 passes through the heater core 56 of the 2-cooling water circuit. As a result, the air blown into the passenger compartment can be effectively heated with the cooling water of the heater core 56 to satisfy the heating requirement in the passenger compartment.

  Here, when the three-way valve 57 is operated so that the cooling water of the first cooling water circuit is mixed with the cooling water of the second cooling water circuit in the situation of [1] or [2] above, As the cooling water discharge flow rate of the pump increases, it is desired that the opening degree of the three-way valve 57 on the first cooling water circuit side with respect to the second cooling water circuit side is gradually and accurately increased with accuracy. . In addition, the discharge flow rate of the water pump in this example is the discharge flow rate of the pump when the first water pump 52 and the second water pump 55 are regarded as one water pump.

  As described above, it is desired to gradually change the opening degree of the three-way valve 57 with good responsiveness and accuracy according to the change in the discharge flow rate of the water pump for the following reason. That is, when the discharge rate of the water pump is small, if the opening degree of the three-way valve 57 is too small, for example, under the condition [1], the cooling water tends to stay inside the engine 50 and the cooling water boils. There is a risk. Further, when the water pump discharge flow rate is large, if the opening degree of the three-way valve 57 is too large, for example, under the condition [2], the high-temperature cooling water staying in the engine 50 rapidly flows out of the engine 50. Then, the inside of the engine 50 may become too cold due to the newly flowing cooling water, and the fuel efficiency of the engine 50 may be deteriorated. Further, for example, in the situation of [1] above, the high-temperature cooling water staying in the engine 50 is rapidly flowed out of the engine 50, so that the temperature of the cooling water in the engine 50 or on the downstream side of the engine 50 changes suddenly. Abrupt changes in the temperature of the cooling water may cause cracks in the engine 50 and parts downstream of the engine 50. In order to prevent the above various problems from occurring, the cooling water in the first cooling water circuit is mixed with the cooling water in the second cooling water circuit in the situation of [1] or [2]. When the three-way valve 57 is operated as described above, it is preferable to gradually change the opening degree of the three-way valve 57 with good responsiveness and accuracy according to the change in the discharge flow rate of the water pump.

  In order to realize that the opening degree of the three-way valve 57 is gradually changed with good responsiveness and accuracy according to the change in the discharge flow rate of the water pump as described above, the three-way valve 57 is formed by an electromagnetic valve. Then, it is conceivable to adjust the opening degree of the three-way valve 57 based on the discharge flow rate of the water pump by duty control. Specifically, since the discharge flow rate of the water pump is adjusted to be a target discharge flow rate determined according to the engine operating state, the opening degree of the three-way valve 57 gradually increases as the target discharge flow rate increases. The three-way valve 57 is operated so that By operating the three-way valve 57 in this way, when the cooling water of the first cooling water circuit is mixed with the cooling water of the second cooling water circuit in the situation of the above [1] or [2], Generation | occurrence | production suppression comes to be aimed at.

JP 2008-208716 A

  In the conventional cooling device described above, when the opening degree of the three-way valve 57 is adjusted based on the target discharge flow rate of the water pump, a response delay occurs in the change in the actual discharge flow rate with respect to the change in the target discharge flow rate of the water pump. This may cause the following problems.

  That is, when the target discharge flow rate of the water pump changes, a response delay occurs in the actual discharge flow rate change with respect to the change in the target discharge flow rate, while the opening degree of the three-way valve 57 based on the change in the target discharge flow rate. Changes are made promptly. For this reason, when the target discharge flow rate changes, the opening degree of the three-way valve 57 may become inappropriate with respect to the actual discharge flow rate of the water pump, which causes the various problems described above. There is a risk.

  For example, when the opening degree of the three-way valve 57 is too small under the condition that the actual discharge flow rate of the water pump is small, the cooling water tends to stay inside the engine 50 under the condition [1]. The cooling water may be boiled. Further, when the opening degree of the three-way valve 57 becomes too large under a state where the actual discharge flow rate of the water pump is large, under the condition [2], the inside of the engine 50 is caused by newly flowing cooling water. There is a possibility that the fuel efficiency of the engine 50 may deteriorate due to being too cold. Further, when the opening degree of the three-way valve 57 becomes too large under the condition that the actual discharge flow rate of the water pump is large, the cooling in the engine 50 or the downstream side of the engine 50 is performed under the condition [1]. There is a risk that the temperature of water changes suddenly and cracks occur in parts.

  When the opening degree of the three-way valve 57 is adjusted based on the target discharge flow rate of the water pump, the opening of the three-way valve 57 is taken into account in consideration of the response delay of the actual discharge flow rate of the water pump when the target discharge flow rate changes. It is also conceivable to control the operation of the three-way valve 57 so that the degree is adjusted so that the above-described various problems do not occur. However, in order to control the operation of the three-way valve 57 in this way, it takes a lot of time and labor to develop a control program for the three-way valve 57 for carrying out the operation, which leads to an increase in the manufacturing cost of the cooling device. It will be.

  The present invention has been made in view of such circumstances, and its purpose is to determine the opening degree of a valve for mixing the cooling water of the first cooling water circuit and the cooling water of the second cooling water circuit from the pump. An object of the present invention is to provide a vehicular cooling device capable of realizing the adjustment with a simple configuration when adjusting the appropriate value according to the actual discharge flow rate of the cooling water with high responsiveness and accuracy.

In the following, means for achieving the above object and its effects are described.
According to the first aspect of the present invention, the first cooling water circuit that circulates the cooling water through the inside of the engine by driving the pump, and the second cooling that circulates the cooling water without passing through the engine by the driving of the pump. The flow of cooling water to and from the water circuit is permitted or prohibited by opening or closing the valve. When the circulation of the cooling water between the first cooling water passage and the second cooling water passage is prohibited based on the valve closing, the circulation of the cooling water in the first cooling water circuit is prohibited. . On the other hand, if the circulation of the cooling water between the first cooling water passage and the second cooling water passage is permitted based on the opening of the valve, the cooling water in the first cooling water circuit and the second cooling water circuit Cooling water is mixed.

  The mixing of the cooling water of the first cooling water circuit and the cooling water of the second cooling water circuit based on the opening of the valve is performed, for example, [1] The cooling water staying in the engine when the valve is closed is the same. When the temperature rises to a value that may cause boiling due to the heat generated by the engine, or [2] it becomes necessary to heat the passenger compartment when the valve is closed, and accordingly, the high-temperature cooling water staying inside the engine is removed. This is done when trying to use for heating the passenger compartment. Under such circumstances, when the valve is opened so that the cooling water of the first cooling water circuit is mixed with the cooling water of the second cooling water circuit, the discharge flow rate of the cooling water of the pump increases. Accordingly, it is desired to gradually increase the opening degree of the valve with good responsiveness and accuracy. This is because, as described above, the valve opening degree is gradually changed with good responsiveness and accuracy according to the change in the actual discharge flow rate of the water pump, thereby suppressing the boiling of the cooling water inside the engine. This is because it is preferable from the standpoints of suppressing cracks in parts due to a sudden change in the temperature of the cooling water inside and downstream of the engine, suppressing deterioration in fuel consumption of the engine, and the like.

  Here, in the first aspect of the present invention, a relief valve is used as the valve. This relief valve includes a valve body that is biased in the valve closing direction by the elastic force of a spring and receives a force based on a pressure difference between its upstream pressure and downstream pressure in the valve opening direction. For this reason, the mixing of the cooling water of the first cooling water circuit and the cooling water of the second cooling water circuit is realized by increasing the discharge flow rate of the pump. Specifically, the force acting in the valve opening direction on the valve body based on the pressure difference between the upstream pressure and the downstream pressure of the relief valve acts on the valve body in the valve closing direction due to the elastic force of the spring. By increasing the discharge flow rate of the pump so as to become larger, the relief valve is opened, and mixing of the cooling water of the first cooling water circuit and the cooling water of the second cooling water circuit is realized.

  As described above, when the relief valve is opened by increasing the discharge flow rate of the pump, the opening degree of the relief valve is adjusted with good responsiveness corresponding to the change in the actual discharge flow rate of the pump. That is, when the discharge flow rate of the pump changes, the pressure difference between the upstream pressure and the downstream pressure of the valve body of the relief valve and the magnitude of the force acting on the valve body based on the pressure difference accordingly. Changes quickly, and the opening of the relief valve (valve element) is adjusted quickly and accurately based on the force after the change.

  For this reason, in the process of changing the discharge flow rate of the pump for opening the relief valve according to the engine operating state, etc., a response delay occurs in the change of the relief valve opening with respect to the change of the pump discharge flow rate. Due to the response delay, the opening degree of the relief valve does not become too small under the condition that the pump discharge flow rate is small. If this occurs under the above condition [1], the cooling water tends to stay in the engine and the cooling water may boil, but it is possible to suppress the occurrence of such problems. Also, a response delay occurs in the change in the opening of the relief valve with respect to the change in the discharge flow rate of the pump, and the relief valve opening is too large under the condition where the pump discharge flow rate is high due to the response delay. There is no value. If this occurs under the condition [2] above, the inside of the engine may be overcooled by newly introduced cooling water, and the fuel consumption of the engine may deteriorate, [1] If this occurs, the temperature of the cooling water inside the engine or on the downstream side of the engine may change suddenly, causing cracks in the parts. However, it becomes possible to suppress the occurrence of such problems.

  As described above, by using the relief valve as a valve for mixing the cooling water of the first cooling water circuit and the cooling water of the second cooling water circuit, the valve (relief valve) is changed as the actual discharge flow rate of the pump changes. ) Can be gradually changed with good responsiveness and accuracy, and the occurrence of the various problems described above can be suppressed. Further, it is possible to realize the gradual change of the opening degree of the valve with high responsiveness and accuracy according to the change of the discharge flow rate of the pump with a simple configuration called a relief valve.

  In the second aspect of the invention, the pump that circulates the cooling water using the cooling water of the first cooling water circuit or the cooling water of the second cooling water circuit is driven and controlled by the pump control unit, and the cooling water in the pump is controlled through the driving control. The discharge flow rate is adjusted. The pump control unit adjusts the pump discharge flow rate so as to open and close the relief valve according to the presence or absence of an engine cooling request, in addition to adjusting the pump discharge flow rate according to the engine operating state or the like. The engine cooling request is made, for example, when [1] the cooling water staying in the engine when the relief valve is closed rises to a value that may cause boiling due to heat generated by the engine. The pump control unit adjusts the pump discharge flow rate so that the relief valve is closed when there is no engine cooling request, and the pump control is performed so that the relief valve is opened when the engine cooling request is present. The discharge flow rate of the pump is adjusted by the unit.

  As described above, when the discharge flow rate of the pump is adjusted to open the relief valve when there is an engine cooling request, the discharge flow rate of the pump is made variable according to the engine operating state or the like. . Under these circumstances, when opening the relief valve by increasing the pump discharge flow rate, the relief valve opening corresponds to changes in the actual discharge flow rate of the pump, which is variable according to the engine operating conditions And responsiveness is adjusted. That is, when the discharge flow rate of the pump changes with the change in the engine operating state, the valve body is changed based on the pressure difference between the upstream side pressure and the downstream side pressure of the valve body of the relief valve, and thus the pressure difference. The magnitude of the force acting on the valve changes quickly, and the opening of the relief valve (valve element) is adjusted quickly and accurately based on the force after the change.

  For this reason, in the process of changing the discharge flow rate of the pump for opening the relief valve according to the engine operating state, a response delay occurs in the change in the opening amount of the relief valve with respect to the change in the discharge flow rate of the pump, Due to the response delay, the problem that the cooling water tends to stay in the engine under the condition [1] and the cooling water boils is suppressed. In addition, a response delay occurs in the change in the opening of the relief valve with respect to the change in the discharge flow rate of the pump. Due to the response delay, in the situation of [1] above, in the engine or on the downstream side of the engine. It is also possible to suppress a problem that the temperature of the cooling water changes suddenly to cause a crack in the part.

  Thus, according to the invention described in claim 2, by employing the relief valve, the opening degree of the valve can be changed with good responsiveness and accuracy according to the change in the actual discharge flow rate of the pump. It is possible to suppress the occurrence of this problem with a simple configuration.

  According to a third aspect of the present invention, the pump that circulates the cooling water using the cooling water of the first cooling water circuit or the cooling water of the second cooling water circuit is driven and controlled by the pump controller, and the cooling water in the pump is controlled through the driving control. The discharge flow rate is adjusted. The pump control unit adjusts the pump discharge flow rate so as to open and close the relief valve according to the presence or absence of a heating request in the passenger compartment, in addition to adjusting the pump discharge flow rate according to the engine operating state or the like. The heating request is made, for example, when [2] it becomes necessary to heat the passenger compartment, and accordingly the high-temperature cooling water staying in the engine is used for heating the passenger compartment. When there is no heating request, the pump control unit adjusts the pump discharge flow rate so that the relief valve is closed, and when there is the heating request, the pump control unit sets the relief valve to be open. The discharge flow rate of the pump is adjusted.

  As described above, when the discharge flow rate of the pump is adjusted so that the relief valve is opened when there is a heating request, the discharge flow rate of the pump is made variable according to the engine operating state. Under these circumstances, when opening the relief valve by increasing the pump discharge flow rate, the relief valve opening corresponds to changes in the actual discharge flow rate of the pump, which is variable according to the engine operating conditions And responsiveness is adjusted. That is, when the discharge flow rate of the pump changes with the change in the engine operating state, the valve body is changed based on the pressure difference between the upstream side pressure and the downstream side pressure of the valve body of the relief valve, and thus the pressure difference. The magnitude of the force acting on the valve changes quickly, and the opening of the relief valve (valve element) is adjusted quickly and accurately based on the force after the change.

  For this reason, in the process of changing the discharge flow rate of the pump for opening the relief valve according to the engine operating state, a response delay occurs in the change in the opening amount of the relief valve with respect to the change in the discharge flow rate of the pump, Due to the response delay, it is possible to suppress the occurrence of a problem that the engine becomes excessively cooled by the newly introduced cooling water in the situation [2] and the fuel consumption of the engine deteriorates.

  Thus, according to the invention described in claim 3, by adopting the relief valve, the opening degree of the valve can be changed with good responsiveness and accuracy in accordance with the change of the actual discharge flow rate of the pump, and the above-mentioned problems Can be suppressed with a simple configuration.

  In the invention according to claim 4, the relief valve is opened and closed by adjusting the discharge flow rate of the pump, and the circulation of the cooling water between the first cooling water circuit and the second cooling water circuit is permitted by opening and closing the relief valve. Or prohibited. And if circulation of the cooling water between the first cooling water passage and the second cooling water passage is prohibited based on the closing of the relief valve, the circulation of the cooling water in the first cooling water circuit is prohibited. Is done. Further, when the circulation of the cooling water is permitted between the first cooling water passage and the second cooling water passage based on the opening of the relief valve, the cooling water of the first cooling water circuit and the second cooling water circuit Cooling water is mixed. In the closed state of the relief valve, for example, when the cooling water staying in the engine rises to a value that may cause boiling due to the heat generated by the engine, or the high-temperature cooling staying in the engine When water is to be used for heating the passenger compartment, the discharge flow rate of the pump is adjusted to increase until the relief valve is opened.

  However, if the temperature of the cooling water in the first cooling water circuit is equal to or higher than the determination value for the completion of warm-up of the engine, the cooling water is opened and closed to allow or prohibit the passage of the cooling water in the bypass passage that bypasses the relief valve. The thermo valve is opened, and the cooling water is circulated in the first cooling water circuit through the thermo valve and the bypass passage. For this reason, adjusting the discharge flow rate of the pump to the increase side to open the relief valve as described above is performed only in a situation where the cooling water in the first cooling water circuit is less than the above-described determination value. What is necessary is not necessary when the cooling water in the first cooling water circuit is equal to or higher than the above-described determination value. Therefore, when the cooling water in the first cooling water circuit is equal to or higher than the above determination value, it is not necessary to adjust the discharge flow rate of the pump to the increase side in order to open the relief valve. Energy consumption accompanying driving can be reduced.

  In the invention according to claim 5, the pump that circulates the cooling water using the cooling water of the first cooling water circuit or the cooling water of the second cooling water circuit is driven and controlled by the pump control unit, and the cooling water in the pump is controlled through the driving control. The discharge flow rate is adjusted. The pump control unit adjusts the discharge flow rate of the pump according to the engine operating state and the like, and also adjusts the discharge flow rate of the pump so that the relief valve is closed when there is no engine cooling request. The discharge flow rate of the pump is adjusted so that the relief valve is opened when there is an engine cooling request only under the condition that the temperature of the cooling water is lower than the determination value. The engine cooling request is made, for example, when [1] the cooling water staying in the engine when the relief valve is closed rises to a value that may cause boiling due to heat generated by the engine.

  As described above, when the discharge flow rate of the pump is adjusted to open the relief valve based on the engine cooling request, the discharge flow rate of the pump is made variable according to the engine operating state. . Under these circumstances, when opening the relief valve by increasing the pump discharge flow rate, the relief valve opening corresponds to changes in the actual discharge flow rate of the pump, which is variable according to the engine operating conditions And responsiveness is adjusted. That is, when the discharge flow rate of the pump changes with the change in the engine operating state, the valve body is changed based on the pressure difference between the upstream side pressure and the downstream side pressure of the valve body of the relief valve, and thus the pressure difference. The magnitude of the force acting on the valve changes quickly, and the opening of the relief valve (valve element) is adjusted quickly and accurately based on the force after the change.

  For this reason, in the process of changing the discharge flow rate of the pump for opening the relief valve according to the engine operating state, a response delay occurs in the change in the opening amount of the relief valve with respect to the change in the discharge flow rate of the pump, Due to the response delay, the problem that the cooling water tends to stay in the engine under the condition [1] and the cooling water boils is suppressed. In addition, a response delay occurs in the change in the opening of the relief valve with respect to the change in the discharge flow rate of the pump. Due to the response delay, in the situation of [1] above, in the engine or on the downstream side of the engine. It is also possible to suppress a problem that the temperature of the cooling water changes suddenly to cause a crack in the part.

  As described above, according to the invention described in claim 5, by employing the relief valve, the opening degree of the valve can be changed responsively and accurately in accordance with the change in the actual discharge flow rate of the pump. It is possible to suppress the occurrence of this problem with a simple configuration. According to the fifth aspect of the present invention, since the bypass passage and the thermo valve are provided in parallel with the relief valve in the first cooling water circuit, the discharge flow rate of the pump is increased to open the relief valve. The adjustment to the side may be performed only in a situation where the cooling water in the first cooling water circuit is less than the above-described determination value, and needs to be performed when the cooling water in the first cooling water circuit is equal to or more than the above-described determination value. Absent. Therefore, when the cooling water in the first cooling water circuit is equal to or higher than the above determination value, it is not necessary to adjust the discharge flow rate of the pump to the increase side in order to open the relief valve. Energy consumption accompanying driving can be reduced.

  In the invention described in claim 6, the pump that circulates the cooling water using the cooling water of the first cooling water circuit or the cooling water of the second cooling water circuit is driven and controlled by the pump control unit, and the cooling water in the pump is controlled through the driving control. The discharge flow rate is adjusted. The pump control unit adjusts the pump discharge flow rate according to the engine operating state, etc., and the pump control unit adjusts the pump discharge flow rate so that the relief valve is closed when there is no request for heating in the passenger compartment. And only in the situation where the temperature of the cooling water in the first cooling water circuit is less than the determination value, the discharge flow rate of the pump is adjusted so that the relief valve is opened when the heating request is made. The heating request is made, for example, when [2] it becomes necessary to heat the passenger compartment, and accordingly the high-temperature cooling water staying in the engine is used for heating the passenger compartment.

  As described above, when the pump discharge flow rate is adjusted to open the relief valve based on the heating request, the pump discharge flow rate is made variable according to the engine operating state. . Under these circumstances, when opening the relief valve by increasing the pump discharge flow rate, the relief valve opening corresponds to changes in the actual discharge flow rate of the pump, which is variable according to the engine operating conditions And responsiveness is adjusted. That is, when the discharge flow rate of the pump changes with the change in the engine operating state, the valve body is changed based on the pressure difference between the upstream side pressure and the downstream side pressure of the valve body of the relief valve, and thus the pressure difference. The magnitude of the force acting on the valve changes quickly, and the opening of the relief valve (valve element) is adjusted quickly and accurately based on the force after the change.

  For this reason, in the process of changing the discharge flow rate of the pump for opening the relief valve according to the engine operating state, a response delay occurs in the change in the opening amount of the relief valve with respect to the change in the discharge flow rate of the pump, Due to the response delay, it is possible to suppress the occurrence of a problem that the engine becomes excessively cooled by the newly introduced cooling water in the situation [2] and the fuel consumption of the engine deteriorates.

  Thus, according to the invention described in claim 6, by adopting the relief valve, the opening degree of the valve can be changed with good responsiveness and accuracy according to the change of the actual discharge flow rate of the pump. It is possible to suppress the occurrence of this problem with a simple configuration. According to the fifth aspect of the present invention, since the bypass passage and the thermo valve are provided in parallel with the relief valve in the first cooling water circuit, the discharge flow rate of the pump is increased to open the relief valve. The adjustment to the side may be performed only in a situation where the cooling water in the first cooling water circuit is less than the above-described determination value, and needs to be performed when the cooling water in the first cooling water circuit is equal to or more than the above-described determination value. Absent. Therefore, when the cooling water in the first cooling water circuit is equal to or higher than the above determination value, it is not necessary to adjust the discharge flow rate of the pump to the increase side in order to open the relief valve. Energy consumption accompanying driving can be reduced.

Schematic which shows the whole structure of the cooling water circuit in the cooling device of 1st Embodiment. The schematic diagram which shows the flow of the cooling water before the engine warm-up completion in the cooling water circuit and when the relief valve is closed. The schematic diagram which shows the flow of the cooling water at the time of the relief valve opening before completion of engine warming-up in the cooling water circuit. The schematic diagram which shows the flow of the cooling water at the time of the relief valve closing after completion of engine warm-up in the same cooling water circuit. The schematic diagram which shows the flow of the cooling water at the time of the relief valve opening after completion of engine warm-up in the same cooling water circuit. The schematic diagram which shows the flow of the cooling water at the time of high water temperature after completion of engine warming-up in the cooling water circuit. The flowchart which shows the drive procedure of the water pump in the cooling device of 1st Embodiment. The graph which shows the change of the opening degree of the relief valve accompanying the increase in the discharge flow rate of a water pump. The schematic diagram which shows the whole structure of the cooling water circuit in the cooling device of 2nd Embodiment. The schematic diagram which shows the flow of the cooling water before the engine warm-up completion in the cooling water circuit and when the relief valve is closed. The schematic diagram which shows the flow of the cooling water at the time of the relief valve opening before completion of engine warming-up in the cooling water circuit. The schematic diagram which shows the flow of the cooling water at the time of the relief valve closing after completion of engine warm-up in the same cooling water circuit. The schematic diagram which shows the flow of the cooling water at the time of high water temperature after completion of engine warming-up in the cooling water circuit. The flowchart which shows the drive procedure of the water pump in the cooling device of 2nd Embodiment. Schematic which shows the whole structure of the cooling water circuit in the conventional cooling device. The schematic diagram which shows the flow of the cooling water at the time of the low water temperature of the cooling water circuit in the conventional cooling device. The schematic diagram which shows the flow of the cooling water at the time of the high water temperature of the cooling water circuit in the conventional cooling device.

[First Embodiment]
Hereinafter, a first 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 according to 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 an external command.

  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 thermostat 5 to the water pump 3. It comes to return. 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. Incidentally, the heater core 6 is also a heat utilization device that uses the heat recovered from the exhaust gas by the exhaust heat recovery device 2. The thermostat 5 located 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. 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 radiator 4, and the thermostat 5 and then returns to the water pump 3. The thermostat 5 opens when the temperature of the cooling water after passing through the heater core 6 exceeds a specified value, and allows the cooling water to circulate through the radiator 4. The thermostat 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 is activated so as to dissipate the heat of the cooling water that has passed through the engine 1 when the temperature of the cooling water flowing into the thermostat 5 exceeds a specified value. Is done.

  In the bypass path of the first coolant circuit, the coolant discharged from the water pump 3 returns to the water pump 3 through the engine 1, the relief valve 7, the heater core 6, and the thermostat 5. . 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 relief valve 7 prohibits the circulation of the cooling water through the bypass path of the first cooling water circuit according to the valve closing, and the cooling water of the first cooling water circuit and the second cooling water circuit according to the valve opening. Mix with cooling water. The relief valve 7 includes a valve body 9 that is urged in the valve closing direction by the elastic force of the spring 8 and receives a force based on a pressure difference between its upstream pressure and downstream pressure in the valve opening direction. The opening degree of the valve body 9 is adjusted based on the pressure difference.

  In the cooling device, when the temperature of the cooling water passing through the thermostat 5 is less than the specified value, the thermostat 5 is closed, and the relief valve 7 is closed, Cooling water circulation through the engine 1 is stopped. Further, the opening of the relief valve 7 in the closed state as described above is realized by increasing the discharge flow rate of the water pump 3. More specifically, the force acting in the valve opening direction on the valve body 9 based on the pressure difference between the upstream pressure and the downstream pressure of the relief valve 7 is closed in the valve closing direction by the elastic force of the spring 8. The discharge flow rate of the water pump 3 is increased so as to be larger than the force acting on the water pump 3. As a result, the relief valve 7 is opened, and the cooling water in the first cooling water circuit and the cooling water in the second cooling water circuit are mixed, and the cooling water is circulated through the engine 1 in the first cooling water circuit. Done. In addition, the minimum value of the discharge flow rate of the water pump 3 that can open the relief valve 7 is hereinafter referred to as a valve opening value. The opening degree of the relief valve 7 is gradually increased with good responsiveness and accuracy as the discharge flow rate of the water pump 3 is increased from the valve opening value.

  In the vehicle cooling apparatus described above, the discharge flow rate of the water pump 3 is controlled by the engine cooling control unit 11. In addition, the engine cooling control part 11 when controlling the discharge flow rate of the water pump 3 functions as a pump control part.

  The engine cooling control unit 11 temporarily stores 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. And an electronic control unit having 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 that detects the cooling water temperature thw1 at the outlet of the engine 1 in the first cooling circuit, and a rotation speed sensor 15 that detects the engine rotation speed. And a detection signal from the air flow meter 16 that detects the intake air amount of the engine 1 are input.

  In addition, the vehicle is provided with an air conditioning control unit 13 that controls air conditioning in the vehicle interior, specifically, heating of air in the heater core 6 and control of blowing of the heated air into the vehicle interior. 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.

  2 and 3 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 thermostat 5 and the relief valve 7 are closed. That is, based on the fact that the temperature of the cooling water circulating through the second cooling water circuit is lower than the specified value, the thermostat 5 is closed, and the discharge flow rate of the water pump 3 is set to the valve opening so that the relief valve 7 is closed. Less than the value. Therefore, at this time, as shown in FIG. 2, 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, if the heater is turned on 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 thermostat 5 and the relief valve 7 are closed and circulation of the cooling water in the first cooling water circuit is prohibited, in the situation shown in the following [1] and [2], The discharge flow rate of the water pump 3 is set to be equal to or higher than the valve opening value so as to mix the cooling water in the first cooling water circuit with the second cooling water circuit. [1] When the cooling water staying in the engine 50 when the relief valve 7 is closed rises to a value that may cause boiling due to heat generated by the engine 50. [2] When it is necessary to heat the passenger compartment when the relief valve 7 is closed, and accordingly the temperature of the cooling water passing through the heater core 6 needs to be increased quickly.

  When the thermostat 5 and the relief valve 7 are both closed and the circulation of the cooling water in the first cooling water circuit is prohibited, if the situation [1] or [2] occurs, the water pump 3 The discharge flow rate of the cooling water is increased beyond the valve opening value, and the relief valve 7 is opened. 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 relief valve 7 by the cooling water. To the upstream side of the heater core 6 of the second coolant circuit. In this way, the cooling water of the first cooling water circuit is caused to flow upstream of the heater core 6 of the second cooling water circuit and mixed with the cooling water of the same circuit, and the cooling water circulation in the first cooling water circuit as shown in FIG. Will be done.

  When the relief valve 7 is opened in the situation of [1] above, 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 accordingly stays in the engine 50. The high-temperature cooling water that has been discharged is flowed out of the engine 50. As a result, it is possible to prevent the cooling water staying in the engine 50 from rising due to the heat generated by the engine 50 and boiling. When the relief valve 7 is opened in the situation [2] above, the cooling water in the first cooling water circuit flows into the second cooling water circuit and is mixed with the cooling water in the same circuit as described above. The high-temperature cooling water staying in 50 passes through the heater core 6 of the 2-cooling water circuit. For this reason, the air blown into the passenger compartment can be effectively heated with the cooling water of the heater core 6 to satisfy the heating requirement in the passenger compartment.

  4 and 5 show the flow of cooling water in the cooling device after the warm-up of the engine 1 is completed. Normally, at this time, the thermostat 5 is opened and the relief valve 7 is closed. As shown in FIG. 4, the cooling water circulation in the second cooling water circuit and the main path of the first cooling water circuit are performed. Cooling water is circulated. That is, when the temperature of the cooling water passing through the thermostat 5 is equal to or higher than the specified value, the thermostat 5 is opened and the discharge flow rate of the water pump 3 is less than the valve opening value so that the relief valve 7 is closed. It is said. The above-mentioned specified value related to the valve opening of the thermostat 5 is, for example, when the cooling water temperature thw1 detected by the water temperature sensor 12 reaches the determination value for completion of warming up of the engine 1 (80 ° C. in this example). A value corresponding to the temperature of the cooling water around the thermostat 5 (82 ° C. in this example) is set. At this time, circulation of the cooling water through the bypass path of the first cooling water circuit is prohibited by closing the relief valve 7.

  After the warm-up of the engine 1 is completed, that is, after the thermostat 5 is opened, the flow rate of the coolant passing through the main path of the first coolant circuit is the opening degree of the thermostat 5 that opens and closes in response to the temperature of the coolant. It becomes a value according to. For this reason, when the temperature of the cooling water passing through the thermostat 5 is not so high, such as immediately after the engine 1 is warmed up, the opening of the thermostat 5 becomes small and the cooling water passing through the main path of the first cooling water circuit. The flow rate is reduced. In addition, when the temperature of the cooling water passing through the thermostat 5 becomes high due to increased heat generation of the engine 1 such as during high load operation, the opening degree of the thermostat 5 becomes large and passes through the main path of the first cooling water circuit. The flow rate of cooling water to be increased.

  Thus, even after the warm-up of the engine 1 is completed and the relief valve 7 is closed, even if the thermostat 5 is opened, the opening degree of the thermostat 5 such as immediately after the warm-up of the engine 1 is completed. If it is small, the situation shown in [1] and [2] described above may occur. For this reason, even after the warm-up of the engine 1 is completed and the relief valve 7 is closed and the thermostat 5 is opened, the water pump can be used even when the situation [1] or [2] occurs. 3 is increased to a value equal to or higher than the valve opening value, and the relief valve 7 is opened. As a result, as shown in FIG. 5, the cooling water circulates using both the main path and the bypass path in the first cooling water circuit, and the cooling water passing through the engine 1 is increased. Therefore, in the situation [1], the relief valve 7 is opened to suppress boiling of the cooling water staying in the engine 50. In the state [2], the relief water 7 is opened, so that the cooling water whose temperature is increased by the heat generated by the engine 50 passes through the heater core 6 more. As a result, the air blown into the passenger compartment is effectively heated by the cooling water, and the heating requirement in the passenger compartment can be satisfied.

  By the way, when the temperature of the cooling water passing through the thermostat 5 is increased due to the high load operation of the engine 1 after the warm-up of the engine 1 is completed, the situation shown in the above [1] and [2] does not occur. This is because when the temperature of the cooling water passing through the thermostat 5 is high, the opening degree of the thermostat 5 is increased, and the flow rate of the cooling water passing through the main path of the first cooling water circuit is increased. This is because the amount of cooling water passing through increases, so that the cooling water does not stay in the engine 50 and the cooling water does not boil. Further, when the temperature of the cooling water passing through the thermostat 5 is high, the temperature of the cooling water passing through the heater core 6 is also high, and the air blown into the vehicle interior can be effectively heated by the cooling water. It is. In addition, FIG. 6 has shown the circulation aspect of the cooling water in a cooling device when the opening degree of the thermostat 5 becomes large with the temperature rise of cooling water.

  Next, the driving procedure of the water pump 3 in the cooling device of the present embodiment will be described with reference to the flowchart of FIG. 7 showing the pump driving routine. The pump driving routine is periodically executed through the engine cooling control unit 11 by, for example, a time interruption at predetermined time intervals.

  In this routine, it is first determined whether or not there is an engine cooling request (S101). The engine cooling request is raised to a value at which the cooling water staying in the engine 1 when the situation [1] occurs, that is, when the relief valve 7 is closed, may be boiled due to heat generated by the engine 1. It is made when it is done. The temperature of the cooling water inside the engine 1 includes the cooling water temperature thw1 detected by the water temperature sensor 12, the engine speed and the engine load which are parameters indicating the work amount of the engine 1 (corresponding to the heat generation amount of the engine 1). It is estimated based on the engine operating state. When the estimated cooling water temperature (hereinafter, estimated water temperature thw2) rises to a value that may cause boiling of the cooling water inside the engine 1, the engine cooling request is made. The engine load represents the amount of air taken into the engine 1 for each cycle of the engine 1, and is detected by the engine rotation speed detected by the rotation speed sensor 15 and the air flow meter 16. It is obtained based on the intake air amount of the engine 1.

  If a negative determination is made in the processing of S101, it is determined whether or not there is a heating request in the vehicle interior (S102). Such a vehicle interior heating request is generated when the above situation [2] occurs, that is, when heating in the vehicle interior should be prioritized over the temperature maintenance of the engine 1, for example, the temperature in the vehicle interior. This is done when the air volume is low and the amount of air blown into the vehicle compartment is large. If the determination in step S102 is negative, neither the engine cooling request nor the heating request is present, so that the discharge flow rate of the water pump 3 is less than the valve opening value so that the relief valve 7 is closed. The upper limit is controlled (S104). The discharge flow rate of the water pump 3 at this time is, for example, the cooling water temperature thw1 detected by the water temperature sensor 12, the engine speed that is a parameter representing the work amount of the engine 1 (corresponding to the heat generation amount of the engine 1), and It is variable based on the engine operating state such as engine load. In addition, the discharge flow rate of the water pump 3 at this time is variable depending on the engine operating state such as whether the engine 1 is operating or stopped.

  On the other hand, if the determination in either S101 or S102 is affirmative, there is at least one of the engine cooling request and the heating request, so that the water pump 3 is set to open the relief valve 7. The discharge flow rate is controlled with a value lower than the valve opening value as a lower limit (S103). In addition, the discharge flow rate of the water pump 3 at this time is the engine operation state such as the cooling water temperature thw1, the engine rotation speed and the engine load, and the engine operation such as whether the engine 1 is operating or stopped, as described above. It is variable based on the state.

  Here, in the situation [1] or [2], when the relief valve 7 that is closed is opened by increasing the discharge flow rate of the water pump 3, the actual discharge flow rate of the water pump 3 is As the valve opening value increases, it is desired to gradually increase the opening degree of the relief valve 7 with good responsiveness and accuracy as shown by a solid line in FIG. This is desirable for the following reasons.

  That is, when the discharge flow rate of the water pump 3 is small, if the opening degree of the relief valve 7 is too small, for example, under the condition [1], the cooling water tends to stay inside the engine 1 and the cooling water boils. There is a risk. Further, when the discharge flow rate of the water pump 3 is large, if the opening degree of the relief valve 7 is too large, for example, the high-temperature cooling water staying in the engine 1 rapidly flows out of the engine 1 under the situation [2]. Then, the inside of the engine 1 may become too cold due to newly flowing cooling water, and the fuel consumption of the engine 1 may be deteriorated. Further, for example, in the situation of [1] above, the high-temperature cooling water staying in the engine 1 is rapidly flowed out of the engine 1, so that the temperature of the cooling water in the engine 1 or on the downstream side of the engine 1 changes suddenly. Abrupt changes in the temperature of the cooling water may cause cracks in the engine 1 and parts downstream of the engine 1. In order to prevent the above various problems from occurring, when the relief valve 7 is opened in the situation [1] or [2], the discharge of the water pump 3 is performed. It is preferable to gradually change the opening degree of the relief valve 7 with high responsiveness and accuracy as described above according to the change in flow rate.

  In this respect, the relief valve 7 is urged in the valve closing direction by the elastic force of the spring 8 and receives a force based on a pressure difference between its upstream pressure and downstream pressure in the valve opening direction. It has. For this reason, when the relief valve 7 that is closed is opened, the force acting in the valve opening direction on the valve body 9 based on the pressure difference between the upstream pressure and the downstream pressure of the relief valve 7 is spring-loaded. This is realized by increasing the discharge flow rate of the water pump 3 so as to be larger than the force acting in the valve closing direction on the valve body by the elastic force of 8.

  As described above, when the relief valve 7 is opened by increasing the discharge flow rate of the water pump 3, the opening degree of the relief valve 7 is responsive and accurate in response to changes in the actual discharge flow rate of the water pump 3. Well adjusted. That is, when the discharge flow rate of the water pump 3 changes, the pressure difference between the pressure on the upstream side and the pressure on the downstream side of the valve body 9 of the relief valve 7, and further on the valve body 9 based on the pressure difference. The magnitude of the force to be quickly changed, and the opening degree of the relief valve 7 (valve element 9) is quickly and accurately adjusted based on the force after the change. For this reason, when the discharge flow rate of the water pump 3 for opening the relief valve 7 is changed according to the engine operating state or the like, the relief valve 7 There is no response delay in the change in opening.

  If such a response delay occurs, the opening degree of the relief valve 7 is set to a value that is too small, for example, indicated by a point P1 with respect to an appropriate value (solid line in FIG. 8) under the condition that the discharge flow rate of the water pump 3 is small. If this occurs under the above condition [1], the cooling water tends to stay in the engine 1 and the cooling water may boil. However, in the present embodiment, occurrence of such a problem can be suppressed. Further, as described above, if a response delay occurs in the change in the opening degree of the relief valve 7 with respect to the change in the discharge flow rate of the water pump 3, the relief valve 7 is opened under a state where the discharge flow rate of the water pump 3 is large. There is a possibility that the degree is too large as indicated by the point P2 with respect to the appropriate value (solid line in FIG. 8). If this occurs under the above condition [2], the inside of the engine 1 may become too cold due to newly introduced cooling water, and the fuel consumption of the engine 1 may be deteriorated. [1] If this occurs, the temperature of the cooling water inside the engine 1 or on the downstream side of the engine 1 may change suddenly, causing cracks in the parts. However, in this embodiment, the occurrence of these problems can be suppressed.

According to the embodiment described in detail above, the following effects can be obtained.
(1) By using the relief valve 7 as a valve for mixing the cooling water in the bypass path of the first cooling water circuit and the cooling water in the second cooling water circuit, the actual discharge flow rate of the water pump 3 changes as described above. The opening degree of the valve (relief valve 7) can be gradually changed with good responsiveness and accuracy. As a result, the various problems described above, that is, boiling of cooling water inside the engine 1, cracks in parts due to sudden changes in the temperature of cooling water inside and downstream of the engine 1, and deterioration in fuel consumption of the engine 1, etc. The occurrence of defects can be suppressed. Further, the relief valve 7 can be used to gradually increase the opening degree of the valve with good responsiveness and accuracy as the discharge flow rate of the water pump 3 increases.

  (2) The discharge flow rate of the water pump 3 is controlled based on the engine operating state with a value equal to or higher than the valve opening value as a lower limit when there is an engine cooling request made in the situation of [1] above. For this reason, when the discharge flow rate of the water pump 3 is increased to open the relief valve 7 based on the engine cooling request, the discharge flow rate of the water pump 3 is made variable according to the engine operating state. Become so. Even under such circumstances, the opening degree of the relief valve 7 is adjusted with good responsiveness and accuracy in accordance with the change in the actual discharge flow rate of the water pump 3 which is variable according to the engine operating state. become.

  Therefore, in the process of changing the discharge flow rate of the water pump 3 for opening the relief valve 7 according to the engine operating state when there is an engine cooling request, the relief valve 7 There is no response delay in the change in opening. And it is suppressed that the malfunction that the cooling water tends to stay inside the engine due to the response delay and the cooling water boils under the condition [1]. Further, a response delay occurs in the change in the opening degree of the relief valve 7 with respect to the change in the discharge flow rate of the water pump 3, and due to the response delay, the inside of the engine or the downstream of the engine in the situation [1]. It is also possible to suppress a problem that the temperature of the cooling water on the side changes suddenly and cracks occur in the part. Thus, by adopting the relief valve 7, the opening degree of the valve 7 can be changed with good responsiveness and accuracy in accordance with the change in the discharge flow rate of the water pump 3, and it is easy to cause the various problems described above. It can be suppressed by the configuration.

  (3) Further, the discharge flow rate of the water pump 3 is controlled based on the engine operating state with a value equal to or higher than the valve opening value as a lower limit when there is a heating request made in the situation of [2] above. Therefore, when the discharge flow rate of the water pump 3 is increased so that the relief valve 7 is opened based on the heating request, the discharge flow rate of the water pump 3 is made variable according to the engine operating state. It becomes like this. Even under such circumstances, the opening degree of the relief valve 7 is adjusted with high responsiveness and accuracy in accordance with the change in the discharge flow rate of the water pump 3 that is variable according to the engine operating state.

  For this reason, in the process of changing the discharge flow rate of the water pump 3 for opening the relief valve 7 when there is a heating request in accordance with the engine operating state, the relief valve against the change in the discharge flow rate of the water pump 3 There is no response delay in the change in the opening degree. Then, it is possible to suppress a problem that the fuel consumption of the engine deteriorates due to the response delay due to the excessive cooling of the inside of the engine due to the newly flowing cooling water under the situation [2]. The Thus, by adopting the relief valve 7, the opening degree of the valve 7 can be changed with high responsiveness and accuracy according to the change in the discharge flow rate of the water pump 3, and the above-described problems occur with a simple configuration. Can be suppressed.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS.
The cooling device of this embodiment permits or prohibits the cooling device of the first embodiment from bypassing the bypass valve 21 that bypasses the relief valve 7 and the cooling water in the passage 21 as shown in FIG. A thermo valve 22 that opens and closes as appropriate is added. The thermo valve 22 is provided at a position higher than the outlet portion of the engine 1 in the first coolant circuit, and the temperature is raised by the heat of the engine 1 even when the valve is closed (when the bypass passage 21 is shut off). Receives inflow caused by heat convection of cooling water. The thermo valve 22 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 the cooling water passes through the bypass passage 21. When the temperature of the cooling water is equal to or higher than the determination value, the valve is opened by receiving heat of the cooling water.

  10 and 11 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 completion of warming-up of the engine 1. Normally, at this time, as in the first embodiment, both the thermostat 5 and the relief valve 7 are closed, and as shown in FIG. 10, the circulation of the cooling water in the first cooling water circuit is prohibited and the second cooling is performed. Cooling water is circulated only in the water circuit. That is, the cooling water at this time is circulated from the water pump 3 through the exhaust heat recovery device 2, the heater core 6, and the thermostat 5.

  When the thermostat 5 and the relief valve 7 are both closed and the circulation of the cooling water in the first cooling water circuit is prohibited, if the situation [1] or [2] occurs, the water pump 3 is increased to a value equal to or higher than the valve opening value, and the relief valve 7 is opened. As a result, the cooling water of the first cooling water circuit flows upstream of the heater core 6 of the second cooling water circuit and is mixed with the cooling water of the same circuit, and passes through the bypass path of the first cooling water circuit as shown in FIG. The cooling water is circulated in the same circuit. At this time, although the cooling water of the first cooling water circuit flows into the thermo valve 22 of the bypass passage 21 by heat convection or the like, the temperature of the cooling water is lower than the above determination value, so the thermo valve 22 is in the closed state. Thus, the passage of the cooling water in the bypass passage 21 is prohibited.

  FIG. 12 shows the flow of cooling water in the cooling device after the warm-up of the engine 1 is completed. Normally, at this time, the thermostat 5 is opened and the relief valve 7 is closed, and 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. It becomes like this. That is, when the temperature of the cooling water passing through the thermostat 5 is equal to or higher than the specified value, the thermostat 5 is opened and the discharge flow rate of the water pump 3 is less than the valve opening value so that the relief valve 7 is closed. It is said. However, at this time, since the cooling water of the first cooling water circuit flowing into the thermo valve 22 of the bypass passage 21 by thermal convection becomes equal to or higher than the determination value, the thermo valve 22 is opened and the cooling water of the bypass passage 21 is opened. The passage is permitted, and the cooling water in the circuit is also circulated through the bypass passage (the bypass passage 21) of the first cooling water circuit.

  As described above, after the warm-up of the engine 1 is completed, that is, when the temperature of the cooling water in the first cooling water circuit is equal to or higher than the determination value, the cooling water in the first cooling water circuit is passed through the thermo valve 22 and the bypass passage 21. Since the circulation is performed, it is not necessary to adjust the discharge flow rate of the water pump 3 to be higher than the valve opening value for the purpose of opening the relief valve 7 for the circulation. Therefore, when the cooling water in the first cooling water circuit is equal to or higher than the determination value, it is not necessary to adjust the discharge flow rate of the water pump 3 to be higher than the valve opening value so that the relief valve 7 is opened. The electric energy used for driving the water pump 3 can be reduced accordingly.

  When the temperature of the cooling water passing through the thermostat 5 is increased due to high load operation of the engine 1 after the warm-up of the engine 1 is completed and the opening of the thermostat 5 is increased, the above [1] and The situation shown in [2] does not occur. In addition, FIG. 13 has shown the circulation mode of the cooling water in a cooling device when the opening degree of the thermostat 5 becomes large as mentioned above with the temperature rise of cooling water.

  Next, the driving procedure of the water pump 3 in the cooling device of the present embodiment will be described with reference to the flowchart of FIG. 14 showing the pump driving routine. In this pump drive routine, the process of S201 is added to the pump drive routine of the first embodiment, and is periodically executed by a time interruption every predetermined time through the engine cooling control unit 11 as in the routine. .

  In the pump drive routine of FIG. 14, first, it is determined whether or not the coolant temperature thw1 detected by the water temperature sensor 12 is less than the above-described determination value, in other words, whether or not the engine 1 has been warmed up. (S201). If the determination is affirmative, there is one of an engine cooling request and a heating request. Based on the affirmative determination of one of S202 and S203, the discharge flow rate of the water pump 3 is set to a value that is equal to or greater than the above valve opening value. Control is performed based on the engine operating state (S204). Further, when neither engine cooling request nor heating request is made, and negative determinations are made in both S202 and S203, the discharge flow rate of the water pump 3 is controlled based on the engine operating state with the value lower than the valve opening value as the upper limit. (S205). On the other hand, when it is determined in S201 that the coolant temperature thw1 is equal to or higher than the determination value and that the engine 1 has been warmed up, the process of S205 is performed and the discharge flow rate of the water pump 3 is less than the valve opening value. Is controlled based on the engine operating condition.

According to this embodiment, in addition to the effects (1) to (3) of the first embodiment, the following effects can be obtained.
(4) If the temperature of the cooling water in the first cooling water circuit is equal to or higher than the determination value for the completion of warm-up of the engine 1, the passage of the cooling water in the bypass passage 21 that bypasses the relief valve 7 is permitted or prohibited. The thermo valve 22 that opens and closes as needed is opened, and the cooling water is circulated in the first cooling water circuit through the thermo valve 22 and the bypass passage 21. For this reason, adjusting the discharge flow rate of the water pump 3 to be equal to or higher than the valve opening value so as to open the relief valve 7 is limited to a situation where the cooling water in the first cooling water circuit is less than the determination value. This is not necessary when the cooling water in the first cooling water circuit is equal to or higher than the above-described determination value. Then, adjusting the discharge flow rate of the water pump 3 to be equal to or higher than the valve opening value so that the relief valve 7 is in an open state is that the cooling water in the first cooling water circuit is as shown in the pump drive routine of FIG. It is performed only under the situation where it is less than the above judgment value. Therefore, when the cooling water in the first cooling water circuit is equal to or higher than the above-described determination value, the discharge flow rate of the water pump 3 is adjusted to be increased so as to be equal to or higher than the above valve opening value so that the relief valve 7 is opened. Therefore, electric energy (power consumption) used for driving the water pump 3 can be reduced.

[Other Embodiments]
In addition, each said embodiment can also be changed as follows, for example.
In the first and second embodiments, regarding the control of the water pump 3 for the purpose of opening the relief valve 7 (S103 in FIG. 7, S204 in FIG. 14), when there is an engine cooling request It may be performed only when it is performed, or only when there is a heating request.

  -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.

  -In 2nd Embodiment, you may provide the thermo valve 22 in the position lower than the exit part of the engine 1 in a 1st cooling water circuit. In this case, as a method of opening the thermo valve 22 that does not use the thermal convection of the first cooling water circuit, the thermo valve 22 is formed so that the cooling water slightly flows through the bypass passage 21 when the relief valve 7 is closed, It is conceivable that the thermo valve 22 can be opened by the heat of water.

  DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Waste heat recovery device, 3 ... Water pump, 4 ... Radiator, 5 ... Thermostat, 6 ... Heater core, 7 ... Relief valve, 8 ... Spring, 9 ... Valve body, 11 ... Engine cooling control part, 12 DESCRIPTION OF SYMBOLS ... Water temperature sensor, 13 ... Air-conditioning control part, 15 ... Rotational speed sensor, 16 ... Air flow meter, 21 ... Detour passage, 22 ... Thermo valve.

Claims (6)

A first cooling water circuit that circulates cooling water through the interior of the engine by driving the pump, a second cooling water circuit that circulates cooling water without passing through the engine by driving the pump, and according to valve closing And a valve that inhibits circulation of the cooling water in the first cooling water circuit and mixes the cooling water of the first cooling water circuit and the cooling water of the second cooling water circuit in response to opening of the valve. In a vehicle cooling device,
The valve includes a valve body that is biased in the valve closing direction by an elastic force of a spring and receives a force based on a pressure difference between the pressure on the upstream side and the pressure on the downstream side in the valve opening direction. And a relief valve that adjusts the opening of the valve body based on the above. The vehicle cooling device according to claim 1,
A pump control unit for driving and controlling the pump to adjust the discharge flow rate of the pump;
The pump control unit adjusts the discharge flow rate of the pump to close the relief valve when there is no engine cooling request, and adjusts the pump flow rate to open the relief valve when engine cooling is requested. A vehicle cooling device characterized by adjusting a discharge flow rate. The vehicle cooling device according to claim 1,
A pump control unit for driving and controlling the pump to adjust the discharge flow rate of the pump;
The second cooling water circuit includes an exhaust heat recovery unit that heats the cooling water by exchanging heat between the engine exhaust and the cooling water of the second cooling water circuit, and the air that is blown into the cooling water and the vehicle interior. And a heater core that warms the air by heat exchange with
The pump control unit adjusts the discharge flow rate of the pump so as to close the relief valve when there is no heating request in the passenger compartment, and sets the relief valve open when there is a heating request. A vehicle cooling apparatus characterized by adjusting a discharge flow rate of a pump. The first cooling water circuit includes a bypass passage that bypasses the relief valve, and a thermo valve that opens and closes to permit or prohibit passage of the coolant in the bypass passage,
The thermo valve is closed when the temperature of the cooling water in the first cooling water circuit is lower than a determination value for completion of warming up of the engine, and prohibits the passage of the cooling water in the bypass passage. The vehicle cooling device according to claim 1, wherein when the temperature of the vehicle is equal to or higher than the determination value, the valve is opened by receiving heat of the cooling water. The vehicle cooling device according to claim 4,
A pump control unit for driving and controlling the pump to adjust the discharge flow rate of the pump;
The pump control unit adjusts the discharge flow rate of the pump to close the relief valve when there is no engine cooling request, and the temperature of the cooling water in the first cooling water circuit is less than the determination value The vehicle cooling apparatus characterized by adjusting the discharge flow rate of the pump so that the relief valve is opened when there is an engine cooling request only at the bottom. The vehicle cooling device according to claim 4,
A pump control unit for driving and controlling the pump to adjust the discharge flow rate of the pump;
The second cooling water circuit includes an exhaust heat recovery unit that heats the cooling water by exchanging heat between the engine exhaust and the cooling water of the second cooling water circuit, and the air that is blown into the cooling water and the vehicle interior. And a heater core that warms the air by heat exchange with
The pump control unit adjusts the discharge flow rate of the pump so that the relief valve is closed when there is no request for heating in the vehicle interior, and the temperature of the cooling water in the first cooling water circuit is less than the determination value. The vehicle cooling device, wherein the discharge flow rate of the pump is adjusted so that the relief valve is opened when there is a heating request only under the circumstances.

Images