JP2010174741A - Cooling control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling control device for an internal combustion engine, appropriately determining whether an electric WP need to be operated for checking water temperature. <P>SOLUTION: The cooling control device for the internal combustion engine cools the engine by circulating cooling water by the electric WP. Concretely, after ignition is turned on, the device determines whether the electric WP need to be operated for confirming temperature of cooling water, based on soak time from previous trip to this time trip and estimation value of temperature of cooling water. An operation of the electric WP under the condition where water temperature does not need to be checked, is inhibited thereby. Diffusion of heat caused by the operation of the internal combustion engine during operation of the electric WP for checking water temperature is then inhibited. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cooling control device for an internal combustion engine including an electric water pump.

  This type of technique is proposed in Patent Documents 1 and 2, for example. Patent Document 1 proposes that an electric water pump (hereinafter referred to as “electric WP”) is driven for a predetermined time after the engine is started in order to check the cooling water temperature. Patent Document 2 proposes that the coolant temperature is checked before the engine is started and the electric WP is operated before the engine is started. Note that the operation of the electric WP before starting the engine in Patent Document 2 is not for checking the coolant temperature.

JP 2008-169750 A JP 2004-108159 A

  However, in the technique described in Patent Document 1 described above, there is a case where the electric WP is driven wastefully after the engine is started for checking the coolant temperature (hereinafter, also simply referred to as “water temperature check”). For this reason, if the electric WP is stopped, the heat that should have contributed to the engine warm-up is diffused by keeping it in the engine, and the engine warm-up may be delayed. Also, Patent Document 2 does not describe appropriately determining whether or not the electric WP needs to be operated in order to check the water temperature.

  The present invention has been made to solve the above-described problems, and it is possible to appropriately determine whether or not it is necessary to operate the electric WP in order to check the water temperature. An object is to provide a control device.

  In one aspect of the present invention, a cooling control device for an internal combustion engine that performs cooling by circulating cooling water using an electric water pump has a soak time from a previous trip to a current trip after the ignition is turned on. And an electric water pump operation necessity determination means for determining whether or not the electric water pump needs to be operated in order to check the temperature of the cooling water based on the estimated value of the temperature of the cooling water Is provided.

  The cooling control apparatus for an internal combustion engine performs cooling by circulating cooling water using an electric water pump. The electric water pump operation necessity determination means checks the cooling water temperature based on the soak time from the previous trip to the current trip and the estimated temperature of the cooling water after the ignition is turned on. It is determined whether or not the electric water pump needs to be operated in order to (check the water temperature). Thereby, it can be determined appropriately whether it is necessary to operate an electric water pump for a water temperature check. Therefore, the operation of the electric water pump for the water temperature check in a situation where it is not necessary to perform the water temperature check can be suppressed. Therefore, it is possible to appropriately suppress the diffusion of heat caused by the operation of the internal combustion engine during the driving of the electric water pump for checking the water temperature.

  In one aspect of the cooling control apparatus for an internal combustion engine, when the electric water pump operation necessity determination unit determines that the electric water pump needs to be operated, the electric water pump is started before the internal combustion engine is started. A means for operating the pump is further provided.

  According to this aspect, the water temperature check can be completed before the internal combustion engine is started, and it is possible to effectively suppress the diffusion of heat caused by the operation of the internal combustion engine while the electric water pump is being driven. .

1 is a schematic configuration diagram of a cooling control device for an internal combustion engine in the present embodiment. It is a flowchart which shows the electric WP action | operation necessity determination process in 1st Embodiment. It is a flowchart which shows the electric WP action | operation necessity determination process in 2nd Embodiment.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
[Device configuration]
FIG. 1 is a schematic configuration diagram of a cooling control apparatus 100 for an internal combustion engine in the present embodiment. In FIG. 1, a solid line arrow indicates an example of the flow of cooling water, and a broken line arrow indicates signal input / output. In addition, a solid line (indicated by reference numeral 7) indicated by a bold line indicates a cooling water passage through which the cooling water flows.

  An internal combustion engine cooling control device 100 mainly includes an engine (internal combustion engine) 1, a heater core 2a, a heater blower 2b, a radiator 3, a thermostat 4, an electric water pump (electric WP) 5, and an exhaust heat recovery device. 6a, EGR cooler 6b, cooling water passage 7, cooling water temperature sensor 10, and ECU (Electronic Control Unit) 50.

  A cooling control apparatus 100 for an internal combustion engine is mounted on a vehicle such as a hybrid vehicle, and includes components (engine 1, heater core 2a, exhaust heat recovery device 6a, EGR cooler 6b, etc.) provided in a cooling water passage 7, cooling water, It is a system that cools and warms up by exchanging heat between the two.

  The engine 1 is a device that generates power in a vehicle by burning an air-fuel mixture of fuel and air. A cooling water passage 7 is formed in the engine 1, and heat exchange is performed between the cooling water passing through the cooling water passage 7 and the engine 1, whereby the engine 1 is cooled or warmed up.

  The heater core 2a is a device that warms the air in the vehicle interior with cooling water passing through the inside, and the heater blower 2b is a device that blows air warmed by the heater core 2a into the vehicle interior. Specifically, the air in the vehicle compartment taken in from the heater blower 2b is supplied to the heater core 2a, and the air supplied to the heater core 2a is heated by exchanging heat with cooling water. Blown out.

  The radiator 3 is a device that cools the cooling water passing through the inside by outside air. In this case, cooling of the cooling water in the radiator 3 is promoted by the wind introduced by the rotation of the electric fan (not shown). The thermostat 4 is configured by a valve that opens and closes according to the coolant temperature. Basically, the thermostat 4 shuts off the supply of the cooling water to the radiator 3 by closing when the cooling water temperature is relatively low, and when the cooling water temperature becomes relatively high The valve is opened and cooling water is supplied to the radiator 3.

  The electric WP 5 includes an electric motor, and the cooling water is circulated in the cooling water passage 7 by driving the motor. The electric WP5 is controlled by a control signal S5 supplied from the ECU 50. Specifically, on / off of the operation in the electric WP5, the rotation speed of the motor in the electric WP5, and the like are controlled. The electric WP5 can change the operation state regardless of the engine speed.

  The exhaust heat recovery device 6a is provided on the cooling water passage 7 and is provided on an exhaust passage (not shown) through which the exhaust gas of the engine 1 passes, and heat is generated between the cooling water and the exhaust gas. By exchanging, exhaust heat is recovered. The EGR cooler 6b is provided on the cooling water passage 7 and on the EGR passage (not shown) through which the EGR gas passes, and performs heat exchange between the cooling water and the EGR gas. Cool the EGR gas.

  The cooling water temperature sensor 10 is provided on the cooling water passage 7 on the downstream side of the head of the engine 1 and detects the cooling water temperature (hereinafter also simply referred to as “water temperature”) at that location. The coolant temperature sensor 10 supplies the ECU 50 with a detection signal S10 corresponding to the detected coolant temperature.

The ECU 50 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown), and performs various controls on each component in the cooling control apparatus 100 for the internal combustion engine. Although details will be described later, the ECU 50 functions as an electric water pump operation necessity determination unit in the present invention.
[Electrical WP operation necessity determination]
Next, the operation necessity determination of the electric WP 5 performed by the ECU 50 in the present embodiment will be described. First, the reason why the necessity determination of the operation of the electric WP 5 is performed in the present embodiment will be described.

  For example, when starting a trip, it can be said that it is desirable to stop the electric WP 5 as much as possible to promote warm-up of the main body of the engine 1 and the head and to save power. On the other hand, in a state where the electric WP 5 is stopped (that is, a state in which the flow rate of the cooling water is approximately “0”), the deviation of the cooling water temperature in the cooling water passage 7 is not reflected in the cooling water temperature sensor 10. There is a case. Therefore, when the stop / operation of the electric WP 5 is determined based on the cooling water temperature sensor 10 in a state where the flow rate is substantially “0”, the water temperature is higher than the water temperature detected by the cooling water temperature sensor 10. When the exhaust heat recovery device 6a (for example, in the exhaust heat recovery device 6a) exists in the cooling water passage 7, it can be said that the cooling water may boil due to the stop of the electric WP5.

  Therefore, in order to solve such a problem, at the start of a trip or the like, in order to appropriately check the coolant temperature (water temperature check), control for operating the electric WP 5 for a certain period of time, or the amount of coolant in the coolant passage 7 A control for operating the electric WP 5 so that the cooling water flows for a corresponding amount (that is, a control for circulating the cooling water for one round of the system) is performed.

  However, for example, in a situation where all the cooling water in the cooling water passage 7 is sufficiently cooled or in a situation where the cooling water temperature in the exhaust heat recovery device 6a is sufficiently low, etc. It is considered that it is not particularly necessary to perform control for operating the electric WP5. Conversely, when the electric WP 5 is operated in such a situation, if the electric WP 5 is stopped, the heat that should have contributed to the warm-up of the engine 1 is diffused by keeping the electric WP 5 in the warm-up. Can be said to be delayed.

  Therefore, in this embodiment, at the start of the trip, the ECU 50 needs to operate the electric WP 5 for the water temperature check based on the soak time from the previous trip to the current trip, the estimated value of the cooling water temperature, and the like. It is determined whether or not there is an electric WP5 operation necessity determination.

  Hereinafter, an embodiment for determining whether or not the electric WP 5 is necessary to be performed by the ECU 50 will be specifically described.

(First embodiment)
In the first embodiment, based on the soak time from the previous trip to the current trip, it is determined whether it is necessary to operate the electric WP 5 for the water temperature check. Specifically, the ECU 50 determines that it is not necessary to operate the electric WP 5 for the water temperature check when the soak time is sufficiently long. That is, the ECU 50 cancels the driving of the electric WP 5 for checking the water temperature and permits the electric WP 5 to stop.

  More specifically, when the soak time is longer than a predetermined time (for example, “2 hours”) and the coolant temperature detected by the coolant temperature sensor 10 at the time of ignition is ON, the ECU 50 specifically cools down. When the water temperature is lower than the first predetermined temperature (for example, “60 ° C.”), the stop of the electric WP 5 is permitted. This is because when the soak time is sufficiently long, the relationship that the cooling water temperature detected by the cooling water temperature sensor 10 is lower than the cooling water temperature in the exhaust heat recovery device 6a is established. This is because if the water temperature is low to some extent, it can be said that it is not necessary to operate the electric WP 5 for the water temperature check. In other words, in such a case, it can be assumed that all the cooling water in the cooling water passage 7 is sufficiently cooled, so it can be said that there is no need to perform a water temperature check.

  Further, in the first embodiment, the ECU 50 is specific when the cooling water temperature detected by the cooling water temperature sensor 10 when the ignition is on is sufficiently low even when the soak time is shorter than the predetermined time. If the cooling water temperature is lower than a second predetermined temperature (a temperature lower than the first predetermined temperature, for example, “40 ° C.”), the driving of the electric WP 5 for checking the water temperature is canceled, and the electric WP 5 Allow stop. This is because when the cooling water temperature is sufficiently low, it can be assumed that the engine 1 is hardly operated in the previous trip and the cooling water temperature in the exhaust heat recovery device 6a is sufficiently low. This is because it can be said that it is not necessary to operate the electric WP 5 for checking.

  In the first embodiment, as a result of determining whether or not the electric WP 5 needs to be operated as described above, when it is determined that the electric WP 5 needs to be operated for the water temperature check (that is, the electric WP 5 is prohibited from being stopped). The electric WP 5 is operated immediately after the ignition is turned on, not after the engine 1 is started. That is, the ECU 50 operates the electric WP 5 for checking the water temperature between the ignition ON and the engine start. This is because in the case of a hybrid vehicle, after the ignition is turned on, the engine is started due to a driver's request or the like. Therefore, if the water temperature check can be completed before the engine is started, the engine 1 is operated while the electric WP 5 is being driven. This is because it is possible to suppress the diffusion of heat caused by the above. The ECU 50 determines whether or not the operation of the electric WP5 can be stopped based on the cooling water temperature obtained from the cooling water temperature sensor 10 when the electric WP5 is operated after the electric WP5 is operated as described above. .

  Next, the electric WP operation necessity determination process in the first embodiment will be described with reference to FIG. This process is repeatedly executed by the ECU 50 after the ignition is turned on (that is, at the start of the trip).

  First, in step S101, the ECU 50 sets a flag indicating whether or not to stop the electric WP 5 is permitted (hereinafter referred to as an “electric WP stop permission flag”) to OFF. Then, the process proceeds to step S102.

  In step S102, the ECU 50 determines whether or not the soak time indicating the interval between the current trip and the previous trip is sufficiently long. Specifically, the ECU 50 determines whether or not the soak time is longer than a predetermined time. For example, the predetermined time is set to “2 hours”. If the soak time is longer than the predetermined time (step S102; Yes), the process proceeds to step S103. If the soak time is equal to or shorter than the predetermined time (step S102; No), the process proceeds to step S106.

  In step S103, the ECU 50 determines whether or not the coolant temperature detected by the coolant temperature sensor 10 is low to some extent. Specifically, the ECU 50 determines whether or not the coolant temperature is lower than the first predetermined temperature. For example, the first predetermined temperature is set to “60 ° C.”.

  When the cooling water temperature is lower than the first predetermined temperature (step S103; Yes), the process proceeds to step S104. In this case, since it can be said that it is not necessary to operate the electric WP 5 for the water temperature check, the ECU 50 sets the electric WP stop permission flag to ON (step S104). That is, the driving of the electric WP 5 for checking the water temperature is canceled and the electric WP 5 is allowed to stop. Then, the process ends.

  On the other hand, when the cooling water temperature is equal to or higher than the first predetermined temperature (step S103; No), the process proceeds to step S105. In this case, since it can be said that it is necessary to operate the electric WP 5 for the water temperature check, the ECU 50 sets the electric WP stop permission flag to OFF (step S104). That is, stopping of the electric WP5 is prohibited. Then, the process ends.

  Next, processing after step S106 performed when the soak time is equal to or shorter than the predetermined time (step S102; No) will be described. In step S106, the ECU 50 determines whether or not the coolant temperature detected by the coolant temperature sensor 10 is sufficiently low. Specifically, the ECU 50 determines whether or not the cooling water temperature is lower than the second predetermined temperature. For example, the second predetermined temperature is set to “40 ° C.”.

  When the cooling water temperature is lower than the second predetermined temperature (step S106; Yes), the process proceeds to step S104. In this case, since it can be said that it is not necessary to operate the electric WP 5 for the water temperature check, the ECU 50 sets the electric WP stop permission flag to ON (step S104). Then, the process ends.

  On the other hand, when the cooling water temperature is equal to or higher than the second predetermined temperature (step S106; No), the process proceeds to step S107. In this case, it can be said that it is necessary to operate the electric WP 5 for the water temperature check.

  In step S107, the ECU 50 executes control for operating the electric WP 5 for the water temperature check. Specifically, the ECU 50 performs control for operating the electric WP 5 for a certain period of time. And ECU50 memorize | stores the maximum value (cooling water temperature maximum value) of the cooling water temperature detected by the cooling water temperature sensor 10 when operating electric WP5 in this way. Then, the process proceeds to step S108. Instead of performing the control for operating the electric WP 5 for a certain period of time as described above, the control for operating the electric WP 5 so that the cooling water flows in the amount corresponding to the amount of cooling water in the cooling water passage 7 (that is, the cooling water for one circuit round) May be executed.

  In step S108, the ECU 50 determines whether or not the maximum coolant temperature value obtained in step S107 is low to some extent, specifically, whether or not it is lower than a first predetermined temperature. When the maximum coolant temperature is less than the first predetermined temperature (step S108; Yes), the process proceeds to step S104. In this case, the ECU 50 sets the electric WP stop permission flag to ON in order to allow the electric WP 5 to stop (step S104). Then, the process ends.

  On the other hand, when the maximum coolant temperature is equal to or higher than the first predetermined temperature (step S108; No), the process proceeds to step S105. In this case, the ECU 50 sets the electric WP stop permission flag to OFF in order to prohibit the electric WP 5 from stopping (step S105). Then, the process ends.

  According to the first embodiment described above, it is possible to appropriately determine whether or not the electric WP 5 needs to be operated for the water temperature check. Therefore, the operation of the electric WP 5 for the water temperature check in a situation where it is not necessary to perform the water temperature check can be suppressed. Thereby, the spreading | diffusion of the heat resulting from operating the engine 1 during the drive of the electric WP5 for a water temperature check can be suppressed appropriately.

  In the flow shown in FIG. 2 above, when the soak time is longer than the predetermined time (step S102; Yes), the electric WP 5 is turned on when the cooling water temperature is lower than the first predetermined temperature (step S103; Yes). In contrast to this, when the cooling water temperature is equal to or higher than the first predetermined temperature (step S103; No), the stop of the electric WP5 is prohibited. Instead, when the soak time is longer than the predetermined time, the electric WP 5 may be allowed to stop regardless of the coolant temperature detected by the coolant temperature sensor 10.

(Second Embodiment)
Next, a second embodiment will be described. In the second embodiment, the temperature of the cooling water in the exhaust heat recovery unit 6a is estimated (hereinafter, the estimated temperature is referred to as “estimated water temperature in the exhaust heat recovery unit”), and based on the estimated water temperature in the exhaust heat recovery unit This is different from the first embodiment in that it is determined whether or not the electric WP 5 needs to be operated for the water temperature check. Specifically, in the second embodiment, the ECU 50 detects the coolant temperature detected by the coolant temperature sensor 10 when the coolant temperature detected by the coolant temperature sensor 10 is higher than the estimated water temperature in the exhaust heat recovery device. When the cooling water temperature is lower than a first predetermined temperature (for example, “60 ° C.”), it is determined that it is not necessary to operate the electric WP 5 for the water temperature check. That is, the ECU 50 cancels the driving of the electric WP 5 for checking the water temperature and permits the electric WP 5 to stop. In such a case, it can be said that it is not necessary to operate the electric WP 5 for the water temperature check.

  Further, even if the coolant temperature detected by the coolant temperature sensor 10 is equal to or lower than the estimated water temperature in the exhaust heat recovery device, the ECU 50 specifically recovers the exhaust heat when the estimated water temperature in the exhaust heat recovery device is low to some extent. When the in-vessel estimated water temperature is lower than a third predetermined temperature (for example, “50 ° C.”), the driving of the electric WP 5 for checking the water temperature is canceled and the electric WP 5 is allowed to stop. In such a case, it can be said that it is not necessary to operate the electric WP 5 for the water temperature check.

  Next, the electric WP operation necessity determination process in the second embodiment will be described with reference to FIG. This process is repeatedly executed by the ECU 50 after the ignition is turned on (that is, at the start of the trip).

  First, in step S201, the ECU 50 sets the electric WP stop permission flag to OFF. Then, the process proceeds to step S202.

  In step S202, the ECU 50 obtains the estimated water temperature in the exhaust heat recovery device. Specifically, the ECU 50 estimates the cooling water temperature in the exhaust heat recovery device 6a from the exhaust gas temperature and the like during the trip, and even during soaking, the ECU 50 releases the heat from the exhaust heat recovery device 6a from the soak time and the outside air temperature. By calculating the amount of heat, the estimated water temperature in the exhaust heat recovery unit is obtained. Then, the process proceeds to step S203.

  In step S203, the ECU 50 determines whether or not the cooling water temperature detected by the cooling water temperature sensor 10 is higher than the estimated water temperature in the exhaust heat recovery unit obtained in step S202. When the cooling water temperature is higher than the estimated water temperature in the exhaust heat recovery device (step S203; Yes), the process proceeds to step S204, and when the cooling water temperature is equal to or lower than the estimated water temperature in the exhaust heat recovery device (step S203; No). The process proceeds to step S207.

  In step S204, the ECU 50 determines whether or not the coolant temperature detected by the coolant temperature sensor 10 is low to some extent. Specifically, the ECU 50 determines whether or not the coolant temperature is lower than the first predetermined temperature. For example, the first predetermined temperature is set to “60 ° C.”.

  When the cooling water temperature is lower than the first predetermined temperature (step S204; Yes), the process proceeds to step S205. In this case, since it can be said that it is not necessary to operate the electric WP 5 for the water temperature check, the ECU 50 sets the electric WP stop permission flag to ON (step S205). That is, the driving of the electric WP 5 for checking the water temperature is canceled and the electric WP 5 is allowed to stop. Then, the process ends.

  On the other hand, when the cooling water temperature is equal to or higher than the first predetermined temperature (step S204; No), the process proceeds to step S206. In this case, since it can be said that it is necessary to operate the electric WP 5 for the water temperature check, the ECU 50 sets the electric WP stop permission flag to OFF (step S206). That is, stopping of the electric WP5 is prohibited. Then, the process ends.

  Next, the process after step S207 performed when the cooling water temperature is equal to or lower than the estimated water temperature in the exhaust heat recovery device (step S203; No) will be described. In step S207, the ECU 50 determines whether or not the estimated water temperature in the exhaust heat recovery device obtained in step S202 is low to some extent, specifically, whether or not the estimated water temperature in the exhaust heat recovery device is lower than a third predetermined temperature. judge. For example, the third predetermined temperature is set to “50 ° C.”.

  If the estimated water temperature in the exhaust heat recovery device is lower than the third predetermined temperature (step S207; Yes), the process proceeds to step S205. In this case, since it can be said that it is not necessary to operate the electric WP 5 for the water temperature check, the ECU 50 sets the electric WP stop permission flag to ON (step S205). Then, the process ends.

  On the other hand, when the estimated water temperature in the exhaust heat recovery device is equal to or higher than the third predetermined temperature (step S207; No), the process proceeds to step S208. In this case, it can be said that it is necessary to operate the electric WP 5 for the water temperature check.

  Since the processing of steps S208 and S209 is the same as the processing of steps S107 and S108 described above (see FIG. 2), the description thereof is omitted.

  Also according to the second embodiment described above, it is possible to appropriately determine whether or not the electric WP 5 needs to be operated for the water temperature check. Thereby, it is possible to appropriately suppress the diffusion of heat caused by the operation of the engine 1 during driving of the electric WP 5 for checking the water temperature.

1 Engine 2a Heater Core 3 Radiator 4 Thermostat 5 Electric Water Pump (Electric WP)
6a Exhaust heat recovery unit 7 Cooling water passage 10 Cooling water temperature sensor 50 ECU
100 Cooling control device for internal combustion engine

Claims (2)

A cooling control device for an internal combustion engine that performs cooling by circulating cooling water using an electric water pump,
After the ignition is turned on, the electric water pump is used to check the temperature of the cooling water based on the soak time from the previous trip to the current trip and the estimated temperature of the cooling water. A cooling control apparatus for an internal combustion engine, comprising: an electric water pump operation necessity determination means for determining whether or not it is necessary to operate.   The apparatus according to claim 1, further comprising means for operating the electric water pump before starting the internal combustion engine when the electric water pump operation necessity determining means determines that the electric water pump needs to be operated. The internal combustion engine cooling control apparatus.

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