JP2010190048A - Cooling control device for internal combustion engine - Google Patents

Abstract

A cooling control device for an internal combustion engine capable of appropriately setting an operation time of an electric WP for checking a water temperature.
A cooling control device for an internal combustion engine performs cooling by circulating cooling water using an electric WP. The heat generation amount estimation means estimates the heat generation amount of the internal combustion engine at the previous trip, and the operation time change means confirms the temperature of the cooling water at the start based on the estimated heat generation amount of the internal combustion engine (water temperature The operation time of the electric WP for checking) is changed. For example, the operation time is set shorter as the calorific value is smaller. Thereby, the operation time of the electric WP for the water temperature check at the time of starting can be shortened appropriately. Therefore, useless operation of the electric WP can be suppressed, power consumption can be reduced, and heat diffusion can be prevented.
[Selection] Figure 4

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 Document 1, 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.

JP 2008-169750 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.

  The present invention has been made to solve the above-described problems, and provides a cooling control device for an internal combustion engine capable of appropriately setting the operation time of the electric WP for checking the water temperature. Objective.

  In one aspect of the present invention, an internal combustion engine cooling control apparatus that performs cooling by circulating cooling water using an electric water pump includes: a heat generation amount estimation unit that estimates a heat generation amount of the internal combustion engine during a previous trip; Operating time changing means for changing the operating time of the electric water pump for checking the temperature of the cooling water at the start based on the heat generation amount of the internal combustion engine estimated by the heat generation amount estimating means. .

  The cooling control apparatus for an internal combustion engine performs cooling by circulating cooling water using an electric water pump. The heat generation amount estimation means estimates the heat generation amount of the internal combustion engine at the previous trip, and the operation time change means confirms the temperature of the cooling water at the start based on the estimated heat generation amount of the internal combustion engine (water temperature Change the operating time of the electric water pump to check). For example, the operation time of the electric water pump is set shorter as the calorific value of the internal combustion engine is smaller. Thereby, the operation time of the electric water pump for the water temperature check at the time of starting can be shortened appropriately. Therefore, useless operation of the electric water pump can be suppressed, power consumption can be reduced, and heat diffusion can be prevented.

  In a preferred example, the heat generation amount estimation means estimates the heat generation amount of the internal combustion engine based on the integrated intake air amount.

  In another preferred example, the heat generation amount estimation means estimates the heat generation amount of the internal combustion engine based on the operation time of the internal combustion engine.

1 is a schematic configuration diagram of a cooling control device for an internal combustion engine in the present embodiment. It is a figure for demonstrating the method for determining electric WP operation time based on the estimated engine heat generation amount. It is a figure for demonstrating the control method in this embodiment concretely. It is a flowchart which shows the control processing in this 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 a calorific value estimating means and an operation time changing means in the present invention.
[Control method]
Next, control performed by the ECU 50 in this embodiment will be described. In the present embodiment, the ECU 50 sets the operating time of the electric WP 5 for checking the cooling water level at the start based on the engine heat generation amount at the previous trip.

  The reason for this is as follows. For example, in the initial trip, it can be said that it is desirable to stop the electric WP 5 as much as possible in order 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.

  In order to solve such a problem, generally, in order to appropriately check the cooling water temperature (water temperature check) at the initial stage of trip, etc., and to equalize the cooling water temperature in the cooling water passage 7. Then, control for operating the electric WP 5 for a predetermined time is performed. However, due to the operation of the electric WP5, the heat inside the engine 1 is diffused to the outside, and the warm-up property of the engine 1 may be deteriorated. Therefore, it can be said that the operation time of the electric WP 5 for checking the water temperature at the initial stage of the trip is desirably as short as possible.

  For example, when the previous trip was a light load operation or a short time operation, it can be determined that the deviation of the cooling water temperature in the cooling water passage 7 is small (that is, it can be determined that the temperature unevenness of each part of the engine is small). Therefore, it can be said that the operation time of the electric WP 5 for the water temperature check should be shortened in the initial trip of this time. On the other hand, for example, if the previous trip was a high load operation or a long time operation, it can be determined that the cooling water temperature in the cooling water passage 7 has a large deviation (that is, the temperature unevenness of each part of the engine is large). Therefore, it can be said that the operation time of the electric WP 5 for checking the water temperature should be increased in the initial stage of the trip.

  Therefore, in this embodiment, the ECU 50 estimates the engine heat generation amount at the previous trip, and sets the operation time of the electric WP 5 at the time of the water temperature check at the start of the trip based on the engine heat generation amount. Specifically, the ECU 50 sets the operation time of the electric WP 5 to be shorter as the estimated engine heat generation amount is smaller. Thereby, the operation time of electric WP5 for the water temperature check in the early stage of a trip can be shortened appropriately. Therefore, power consumption can be reduced and heat diffusion can be prevented.

  FIG. 2 is a diagram showing an example of a map for determining the operation time of the electric WP 5 based on the engine heat generation amount. FIG. 2 shows the estimated engine heat generation amount (estimated engine heat generation amount) on the horizontal axis, and the operating time of the electric WP 5 on the vertical axis. As shown in the figure, it can be seen that the operating time of the electric WP 5 becomes shorter as the engine heat generation amount becomes smaller. The ECU 50 determines the operating time of the electric WP 5 corresponding to the estimated engine heat generation amount with reference to such a map.

  Furthermore, in the present embodiment, the ECU 50 determines whether or not the electric WP 5 needs to be operated for the water temperature check based on the soak time from the previous trip to the current trip. Specifically, when the soaking time is longer than a predetermined time (for example, “2 hours”) and the cooling water temperature detected by the cooling water temperature sensor 10 at the time of ignition is ON, When the temperature is lower than a first predetermined temperature (for example, “60 ° C.”), the driving of the electric WP 5 for checking the water temperature is canceled and the electric WP 5 is allowed to stop.

  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 present embodiment, the ECU 50 specifically specifies that 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 the second predetermined temperature (a temperature lower than the first predetermined temperature, for example, “40 ° C.”), the driving of the electric WP 5 for water temperature check is canceled and the electric WP 5 is stopped. Allow. This is because when the cooling water temperature is sufficiently low, the engine 1 is hardly operated in the previous trip, and it can be assumed that 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 the water temperature check.

  Here, with reference to FIG. 3, the control method in this embodiment is demonstrated concretely. FIG. 3 shows time in the horizontal direction, and in order from the top, the ignition (IG) signal, the vehicle speed, the engine speed, the coolant temperature (the sensor value of the coolant temperature sensor 10), the operating state 1 of the electric WP5, The operating state 2 of the electric WP5 is shown. “Operating state 1 of electric WP5” corresponds to the operating state of electric WP5 when the control method in the present embodiment described above is performed, that is, when the operating time of electric WP5 is set based on the engine heat generation amount. On the other hand, the “operating state 2 of the electric WP 5” is the electric WP 5 when the control method in the present embodiment is not performed, that is, when the operating time of the electric WP 5 is not set based on the engine heat generation amount. Corresponds to the operating state.

  The first period T1 corresponds to the first trip period, the next period T2 corresponds to the first soak period, the next period T3 corresponds to the second trip period, and the next period T4 corresponds to the second soak period, and the next period T5 corresponds to the third trip period. Note that the soak time in the soak periods T2 and T4 is shorter than the above-described predetermined time (for example, “2 hours”). Further, the cooling water temperature (for example, “70 ° C.”) indicated by “th1” corresponds to a temperature at which the electric WP 5 should be operated in order to cool the engine 1 or the like if the temperature is higher than the temperature. In addition, if the cooling water temperature (for example, “40 ° C.”) indicated by “th2” is equal to or higher than the temperature at the start of the trip, it corresponds to the temperature at which the electric WP 5 should be operated for the water temperature check.

  As shown in FIG. 3, in the middle of the first trip period T1, the coolant temperature exceeds the temperature th1, so that the electric WP 5 is operated to cool the engine 1 and the like as indicated by the broken line area A1. Thereafter, since the cooling water temperature exceeds the temperature th2 at the start of the second trip period T3 after the soak, the electric WP5 is operated to check the water temperature as indicated by the broken line area A2. In the second trip period T3, as indicated by the broken line area A3, the engine 1 is not operated because of light load traveling.

Thereafter, when the control method according to the present embodiment is performed at the start of the third trip period T5 after the soak, the engine 1 is not operated in the previous trip (second trip), so the engine heat is generated. Since it can be said that the amount is substantially 0, the electric WP5 is not operated (in other words, the operation time of the electric WP5 is set to 0) as indicated by the broken line area A4. That is, even if the coolant temperature exceeds the temperature th2, the electric WP5 is not operated. On the other hand, when the control method in the present embodiment is not performed, the cooling water temperature exceeds the temperature th2 at the start of the third trip period T5. The electric WP5 is activated to check the water temperature.
[Control processing]
Next, with reference to FIG. 4, the control process in this embodiment is demonstrated. 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. Therefore, in steps S107 to S109, a process for operating the electric WP5 is performed.

  In step S107, the ECU 50 estimates the engine heat generation amount. In one example, the ECU 50 estimates the engine heat generation amount based on the integrated intake air amount at the previous trip. In this case, the ECU 50 performs the estimation with reference to a map in which the engine heat generation amount is associated with the integrated intake air amount. In another example, the ECU 50 estimates the engine heat generation amount based on the operation time of the engine 1 at the previous trip. In this case, the ECU 50 performs the estimation with reference to a map in which the engine heat generation amount is associated with the operation time of the engine 1. When the above process ends, the process proceeds to step S108.

  In step S108, the ECU 50 determines the operation time of the electric WP 5 for the water temperature check based on the engine heat generation amount estimated in step S107. For example, the ECU 50 refers to a map as shown in FIG. 2 and determines the operation time of the electric WP 5 corresponding to the estimated engine heat generation amount. Then, the process proceeds to step S109.

  In step S109, the ECU 50 performs control for operating the electric WP5 for the operation time of the electric WP5 determined in step S108 for the water temperature check. Then, the process proceeds to step S104. In step S104, the ECU 50 sets the electric WP stop permission flag to ON in order to permit the electric WP5 to stop. Then, the process ends.

  According to the control process described above, it is possible to appropriately shorten the operation time of the electric WP 5 when checking the water temperature at the start of the trip. Therefore, useless operation of the electric WP 5 can be suppressed, power consumption can be reduced, and heat diffusion can be prevented.

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 (3)

A cooling control device for an internal combustion engine that performs cooling by circulating cooling water using an electric water pump,
A calorific value estimating means for estimating the calorific value of the internal combustion engine at the previous trip;
An operation time changing means for changing an operation time of the electric water pump for checking the temperature of the cooling water at the start based on the heat generation amount of the internal combustion engine estimated by the heat generation amount estimation means; A cooling control apparatus for an internal combustion engine, comprising:   The cooling control apparatus for an internal combustion engine according to claim 1, wherein the heat generation amount estimation means estimates the heat generation amount of the internal combustion engine based on an integrated intake air amount.   The cooling control apparatus for an internal combustion engine according to claim 1, wherein the heat generation amount estimation means estimates the heat generation amount of the internal combustion engine based on an operation time of the internal combustion engine.

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