JP2010242550A - Control device for cooling device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately determine the boiling state of cooling water in a cooling device of an internal combustion engine such as an engine. <P>SOLUTION: This control device (100) for a cooling device (300) capable of cooling the engine (200) and the exhaust gas thereof by circulating cooling water by an electric WP (320) includes a stop prohibition means (100) for prohibiting the stop of the electric WP when first cooling water temperature exceeds a first boiling reference temperature or a second cooling water temperature exceeds a second boiling reference temperature, and a correction means (100) for correcting a temperature of a small difference between the corresponding first and secure cooling temperatures out of first and secure boiling reference temperatures when water pressure exceeds a corresponding pressure threshold to a low-temperature side, and corrects the first and secure boiling reference temperatures to high-temperature sides when the water pressure does not exceed the pressure threshold. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technical field of a control device that controls a cooling device for an internal combustion engine.

  As this type of control device, for example, there is a control device provided in an exhaust heat recovery device of an internal combustion engine disclosed in Patent Document 1. According to this control device, based on the water pressure of the cooling water detected by the water pressure sensor installed in the cooling water channel, it is determined whether or not the cooling water is in a nucleate boiling state. Thus, an electric WP (Water Pump: water pump or electric pump) that circulates cooling water is controlled.

JP 2008-157090 A

  According to the knowledge of the present inventor, in this type of cooling device, when the electric WP is stopped, the temperature of the cooling water is set to avoid leakage of cooling water due to boiling of the cooling water in the cooling water passage. It is preferable to maintain the temperature range so that it does not boil. On the other hand, in order to reduce fuel consumption, it is preferable to maintain the temperature of the cooling water in a high water temperature range. Therefore, in order to maintain the temperature of the cooling water in a temperature range that does not boil and has a high water temperature, it is very preferable to determine the boiling state of the cooling water with high accuracy.

  However, Patent Document 1 described above does not have a specific description regarding determining the boiling state of the cooling water with high accuracy when the electric WP is stopped as described above. That is, there is a technical problem that it is difficult to appropriately achieve both avoidance of boiling of cooling water and reduction in fuel consumption by accurately discriminating the boiling state.

  The present invention has been made in view of, for example, the above-described problems, and an object of the present invention is to provide a control device for a cooling device for an internal combustion engine that can accurately determine the boiling state of cooling water.

  In order to solve the above-described problems, a control device for a cooling device for an internal combustion engine according to the present invention is an internal combustion engine and a cooling device capable of cooling the exhaust discharged from the internal combustion engine by circulating cooling water using an electric water pump. A control device for controlling stop of the electric water pump, wherein the cooling water includes a first temperature specifying means for specifying a first cooling water temperature that is a temperature of an internal combustion engine cooling portion for cooling the internal combustion engine, and the cooling Second temperature specifying means for specifying a second cooling water temperature that is a temperature of an exhaust cooling portion for cooling the exhaust of water, water pressure specifying means for specifying a water pressure of the cooling water, and the specified first cooling water When the temperature exceeds the currently set first boiling reference temperature, or the specified second cooling water temperature exceeds the currently set second boiling reference temperature, the power Stop prohibiting means for prohibiting the stop of the water pump, the specified first cooling water temperature does not exceed the currently set first boiling reference temperature, and the specified second cooling temperature is When the currently set second boiling reference temperature is not exceeded, (b) if the specified water pressure exceeds a pressure threshold value set in advance as a pressure corresponding to the boiling state, the first boiling reference temperature Of the temperature and the second boiling reference temperature, the one with the smaller difference from the corresponding first or second cooling water temperature is corrected to the low temperature side, and (b) the specified water pressure exceeds the pressure threshold value. If not, it comprises correction means for correcting at least one of the first boiling reference temperature and the second boiling reference temperature to the high temperature side.

  According to the control apparatus for a cooling apparatus for an internal combustion engine according to the present invention, when the first cooling water temperature exceeds the first boiling reference temperature or the second cooling water temperature exceeds the second boiling reference temperature, the electric water pump Stopping is prohibited. Here, “exceeding temperature” may have any of the above meanings or the meaning of becoming larger. Therefore, it becomes possible to avoid boiling of cooling water quickly and reliably.

  Conversely, when the first cooling water temperature does not exceed the first boiling reference temperature and the second cooling temperature does not exceed the second boiling reference temperature, (b) if the water pressure of the cooling water exceeds the pressure threshold Of the first and second boiling reference temperatures, the smaller difference from the corresponding first or second cooling water temperature is corrected to the low temperature side. Here, “the smaller difference between the corresponding first or second cooling water temperature” means the difference between the first boiling reference temperature and the first cooling water temperature, the second boiling reference temperature, and the second cooling water temperature. Are compared with each other, and the first or second boiling reference temperature with the smaller difference is meant. On the other hand, (b) if the water pressure of the cooling water does not exceed the pressure threshold, at least one of the first and second boiling reference temperatures is corrected to the high temperature side.

  Accordingly, the correction means corrects at least one of the first and second boiling reference temperatures in accordance with the coolant pressure, so that, for example, the discrimination between the vehicle and the internal combustion engine or the type of coolant can be reduced. The adverse effect on the discrimination accuracy of the boiling state of water is alleviated. Therefore, it is possible to maintain a high determination accuracy of the boiling state. It is also possible to suppress the margin in consideration of the boiling state determination error.

  As a result, particularly when the electric WP is stopped, it is possible to accurately execute the electric WP stop control during the electric WP stop period by determining the boiling state of the cooling water with high accuracy. Therefore, it is possible to achieve both avoidance of boiling of the cooling water and reduction in fuel consumption by this electric WP stop control with a very appropriate balance.

  In particular, for the first and second boiling reference temperatures, the corresponding first or second boiling point when the first cooling water temperature does not exceed the first boiling reference temperature and the second cooling temperature does not exceed the second boiling reference temperature. Since the smaller difference with the 2 cooling water temperature is corrected to the low temperature side, only one which needs to be learned is corrected. Correcting only the reference temperature of the person who needs to learn in this way leads to efficient or quick learning, and is extremely useful in practice.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

1 is a schematic configuration diagram conceptually showing a configuration of an engine system including a control device for a cooling device according to an embodiment of the present invention. It is a flowchart of the boiling reference temperature correction process performed in the engine system of FIG. It is a schematic diagram of a boiling reference temperature map. It is a schematic diagram of the difference value of cooling water temperature and boiling reference temperature.

<Embodiment of the Invention>
Embodiments of the present invention will be described below with reference to the drawings.

<Configuration of Embodiment>
First, the configuration of an engine system 10 including a control device for a cooling device according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram conceptually showing the configuration of the engine system 10.

  In FIG. 1, an engine system 10 is mounted on a vehicle and includes an ECU (Electronic Control Unit) 100, an engine 200, and a cooling unit 300.

  The ECU 100 is an electronic control unit that includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and is configured to be able to control the entire operation of the engine system 10. Each of the “first temperature specifying means”, “second temperature specifying means”, “water pressure specifying means”, “stop prohibiting means”, and “correction means specifying means” according to the present invention is configured to function as an example. . Note that the physical, mechanical, mechanical, or electrical configuration of each means according to the present invention is not limited to the ECU 100 that is integrally configured in hardware as long as the function according to the means can be realized. For example, different hardware configurations may be adopted, or various other processing units, various controllers, various computer systems such as a microcomputer device, and the like may be employed.

  The ECU 100 constitutes an example of a “control device for an internal combustion engine cooling device” according to the present invention, and can execute a boiling reference temperature correction process, which will be described later, according to a control program stored in a ROM, for example. Configured.

  The engine 200 constitutes an example of an “internal combustion engine” according to the present invention, and has, for example, a plurality of cylinders. For example, cooling or warming-up with cooling water that passes through a cooling water passage or a cooling water circulation passage as described in detail below is performed for each of the plurality of cylinders.

  The cooling unit 300 is an example of the “cooling device” according to the present invention including the cooling water circulation path 310, the electric WP 320, the radiator 330, the thermostat 340, the heater core 350, and the exhaust heat recovery device 360.

  The cooling water circulation path 310 is a pipe made of, for example, metal or resin that includes a water jacket stretched around the cylinder block of the engine 200 and defines a supply path of cooling water appropriately discharged by the electric WP 320. A part of the cooling water circulation path 310 may be configured to pass through the thick part of the cylinder block.

  The cooling water circulation path 310 includes an engine cooling circulation path 310a, a radiator bypass path 310b, and an exhaust cooling path 310c.

  The engine cooling circuit 310a is configured to recirculate cooling water to the electric WP 320 through the electric WP 320, the engine 200 (mainly a water jacket), the radiator 330, and the thermostat 340 sequentially. Heat exchange is performed between the cooling water passing through the engine cooling circuit 310a and the engine 200, whereby the engine 200 is cooled or warmed up.

  The physical, mechanical, mechanical, or electrical configuration of the “cooling device” according to the present invention is not limited to the engine cooling circuit 310a exemplified here as long as the internal combustion engine can be cooled. Various aspects may be provided.

  The radiator bypass passage 310 b is configured to branch from the engine cooling circulation passage 310 a upstream from the radiator 330 and reach the thermostat 340.

  The exhaust cooling passage 310c branches the engine cooling circulation passage 310a from the downstream side of the water jacket of the engine 200, and the cooling water after sequentially passing through the heater core 350 and the exhaust heat recovery device 360 is cooled again by the thermostat 340. It is comprised so that it may make it merge with the circulation path 310a.

  The electric WP 320 is, for example, a spiral electric drive pump, and is an example of the “electric water pump” according to the present invention. The electric WP 320 is configured to be able to circulate the cooling water in the cooling water circulation path 310 by, for example, sucking the cooling water by the rotational force of the motor and discharging the cooling water in an amount corresponding to the rotational speed of the motor. Has been.

  The physical, mechanical, mechanical or electrical configuration of the “electric water pump” according to the present invention is not particularly limited as long as the cooling water can be circulated, and has various modes. It's okay. For example, the electric WP 320 in the present embodiment may be configured to be able to supply cooling water independently of the engine rotation of the engine 200. In other words, “independently of the engine rotation of the engine 200” is a concept indicating that the rotation state cannot be uniquely determined according to the rotation state of the crankshaft of the engine 200, for example. This means that the amount of cooling water supplied can be controlled without being affected by the engine rotation.

  The configuration of the “electric water pump” according to the present invention is not necessarily limited to the electric drive type, and may be various. For example, it is connected to a crankshaft and can be rotated using a part of the rotational driving force of the crankshaft, and the rotational speed of the crankshaft is binary, for example, the engaging force in a physical engaging means such as a clutch. In addition, it may be a mechanical pump or the like configured to be able to control in a binary, stepwise or continuous manner by variably controlling in a stepwise or continuous manner.

  When the electric WP 320 has a mode in which the engagement force can be changed like the above-described engagement means, the supply amount (that is, the discharge amount) of the cooling water is hardly affected by the engine state of the engine 200, and the control thereof is performed. The upper degrees of freedom are correspondingly higher. For this reason, even if the engine 200 is stopped in an extreme case, it can be driven, which is preferable.

  In the electric WP 320, for example, the motor is supplied with electric power from an electric power supply source (for example, an in-vehicle 12V battery or another battery) and the duty of a control voltage (or current) supplied via the motor drive system. Depending on the ratio, the rotational speed is controlled to increase or decrease. Such a motor drive system is in a state of being electrically connected to the ECU 100 and has a configuration in which the operation state including the above-described duty ratio is controlled by the ECU 100. That is, the electric WP 320 has a configuration in which the operation state is controlled by the ECU 100.

  In the electric WP 320, for example, various control amounts such as electric power, voltage or current supplied through such a power supply source and a motor drive system, or a duty ratio corresponding thereto, for example, the engine speed or load or its Both are controlled according to various operating conditions of the engine 200. With this, or by feeding back the motor rotation number detected by the rotation sensor or the like to these various control amounts, the electric WP 320 can accurately set the motor rotation number, the motor rotation speed, or the pump rotation speed to a target value. And it becomes possible to control easily.

  The radiator 330 is installed in the engine cooling circuit 310a, and a plurality of water pipes are arranged. With a large number of corrugated fins on the outer periphery of the water pipe, when cooling water flows through the water pipe, by heat exchange with the atmosphere through the fins, that is, by dissipating the heat of the cooling water to the outside, The cooling water can be relatively cooled. Therefore, the temperature of the cooling water after passing through the radiator 330 is lower than that of the cooling water before flowing into the radiator 330.

  The thermostat 340 is an example of temperature adjusting means provided to stabilize the “primary cooling water temperature” that is the temperature of the cooling water flowing into the electric WP. Inside the thermostat 340, a control valve for controlling the communication state between the engine cooling circuit 310a and the radiator bypass circuit 310b described above is provided. The thermostat 340 is configured to allow the cooling water after passing through the radiator 330 via the engine cooling circuit 310a to be returned to the electric WP 320 when the control valve is in an open state. The thermostat 340 is electrically connected to the ECU 100, and the open / close state of the control valve is controlled by the ECU 100. The present embodiment has a configuration in which the valve body of the control valve is driven and controlled by the ECU 100 so that the cooling water is used for heat dissipation in the radiator 330 when the temperature of the original cooling water reaches a certain reference temperature. .

  The thermostat 340 includes a control valve that controls the communication state between the radiator bypass passage 310b and the exhaust cooling passage 310c in addition to the control valve that controls the communication state between the engine cooling circulation passage 310a and the radiator bypass passage 310b. One of the control valves may be configured to be opened. Alternatively, a three-way valve may be provided instead of such a plurality of control valves, and an operation equivalent to the operation of the control valve described above may be realized. That is, when the cooling water is supplied to the electric WP 320 by the radiator 330, the exhaust cooling path 310c may be used together, or the use of the exhaust cooling path 310c may be stopped.

  The heater core 350 is configured to function as a heat source of a heating device for heating the inside of the cabin of the vehicle. The heater core 350 is installed on the exhaust cooling path 310c of the cooling water circulation path 310, and is configured to be able to exchange heat with the cooling water supplied to the exhaust cooling path 310c. On the other hand, the heater core 350 communicates with the air conditioning duct of the vehicle, and is configured to be able to raise the temperature of the air sucked into the air conditioning duct by the heat obtained by heat exchange with the cooling water.

  The exhaust heat recovery unit 360 is installed in the exhaust cooling path 310c and is configured to recover exhaust heat from the high-temperature exhaust gas guided into the exhaust pipe of the internal combustion engine 200, that is, to cool the exhaust gas with cooling water. Has been.

  More specifically, the exhaust heat recovery device 360 has a configuration in which a plurality of stainless steel matrix members (or mesh members) as heat storage materials are stacked as a preferable example, and surrounds the exhaust pipe. Is provided. When the exhaust gas passes through the matrix member, heat is exchanged between the exhaust gas discharged from the internal combustion engine 200 and the cooling water led to the exhaust heat recovery device 360, thereby transferring heat from the exhaust gas. At least a part of the exhaust heat is taken away through the exhaust gas, that is, the exhaust gas can be cooled.

  The exhaust heat recovery device 360 may be provided with an adjustment valve that changes the flow of the exhaust gas. By appropriately operating this adjusting valve, the heat exchange between the exhaust gas and the cooling water is adjusted, and the amount of heat recovered from the exhaust gas can be adjusted.

  The “cooling device” according to the present embodiment is not limited to the exhaust heat recovery device 360 illustrated here as long as the exhaust discharged from the engine 200 can be cooled, and has various aspects. Good.

  Here, “cooling the exhaust” means, for example, a part of the exhaust heat from the exhaust led to the exhaust system as a concept including various parts such as an exhaust port, an exhaust manifold, and an exhaust pipe located downstream thereof. At least. As a preferred embodiment, at least a part of the taken exhaust heat is temporarily stored, for example, through some heat storage means, or directly without passing through such a heat storage process. To the cooling water by performing heat exchange as a concept including spatial radiation, physical heat transfer, and the like. Further, the exhaust heat thus taken is converted into, for example, mechanical energy, or converted into electric energy through a heat pump or a thermoelectric conversion module. Thus, “cooling the exhaust” is a broad concept including various forms. As long as such a concept can be satisfied, the physical, mechanical, mechanical, electrical, or chemical configuration of the “cooling device” according to the present embodiment is not limited and may be various.

  An engine-side cooling water temperature sensor 370 capable of detecting an engine-side cooling water temperature Thw1 that is the temperature of the cooling water after cooling the engine 200 on the downstream side of the engine 200 is installed in the engine cooling circuit 310a. The engine-side cooling water temperature sensor 370 is electrically connected to the ECU 100, and the detected engine-side cooling water temperature Thw1 is configured to be referred to by the ECU 100 at a constant or indefinite timing. The engine-side cooling water temperature Thw1 is an example of the “first cooling water temperature” according to the present invention.

  In the exhaust cooling path 310c, on the downstream side of the exhaust heat recovery unit 360, the exhaust side cooling water temperature that can detect the exhaust side cooling water temperature Thw2 that is the temperature of the cooling water after cooling the exhaust gas by the exhaust heat recovery unit 360. A sensor 380 is installed. The exhaust-side cooling water temperature sensor 380 is electrically connected to the ECU 100, and the detected exhaust-side cooling water temperature Thw2 is configured to be referred to by the ECU 100 at a constant or indefinite timing. The exhaust-side cooling water temperature Thw2 is an example of the “second cooling water temperature” according to the present invention.

  In the engine cooling circuit 310a, a water pressure sensor 390 capable of detecting the coolant water pressure Pw in the cooling water circuit 310 is installed on the outlet side of the electric WP 320. The water pressure sensor 390 is electrically connected to the ECU 100, and the detected system water pressure Pw is configured to be referred to by the ECU 100 at a constant or indefinite timing. The system water pressure Pw is an example of the “cooling water pressure” according to the present invention.

<Operation of Embodiment>
<Outline of boiling reference temperature correction processing>
In the engine system 10, when the electric WP 320 is stopped, the ECU 100 performs control so as to prohibit or maintain the stopped state (hereinafter, referred to as “electric WP stop control” as appropriate), whereby the cooling water circulation path 310. The temperature of the cooling water can be adjusted. By this electric WP stop control, the temperature of the cooling water does not boil and is maintained in a high water temperature range, and it is possible to achieve both avoidance of boiling of the cooling water and reduction of fuel consumption.

  More specifically, in the electric WP stop control of the present embodiment, when the electric WP 320 is stopped, the ECU 100 brings the cooling water into a boiling state by comparing the cooling water temperature with a preset reference value. It is determined whether or not there is. Furthermore, the stop of the electric WP 320 is prohibited or maintained according to the determined boiling state of the cooling water.

  On the other hand, in realizing the electric WP stop control, it is assumed that the boiling state of the cooling water is determined with high accuracy as described above. For example, depending on various factors such as discrimination between the vehicle and the engine 200 or the type of cooling water, the boiling state of the cooling water by comparison between the cooling water temperature and a preset reference value may be erroneously determined. Therefore, in the engine system 10, when the electric WP 320 is stopped by the boiling reference temperature correction process executed by the ECU 100, it is quickly and accurately determined whether or not the cooling water is in a boiling state.

<Details of boiling reference temperature correction processing>
Here, with reference to FIG. 2, the detail of a boiling reference temperature correction process is demonstrated. FIG. 2 is a flowchart of the boiling reference temperature correction process.

  In FIG. 2, first, the ECU 100 acquires the engine-side cooling water temperature Thw1 and the exhaust-side cooling water temperature Thw2 by using the engine-side cooling water temperature sensor 370 and the exhaust-side cooling water temperature sensor 380 described above (step S101). The control according to step S101 is an example of the operation of the ECU 100 that functions as the “first temperature specifying means” and the “second temperature specifying means” according to the present invention.

  Acquisition of such step S101 and step S106 mentioned later is an example of "specific" in this invention regarding the temperature and water pressure of cooling water. Here, “specific” according to the present invention refers to, for example, detecting directly or indirectly as a physical numerical value or an electric signal or the like corresponding to the physical numerical value via some detection means, or storing appropriate memory in advance. From the map stored in the means etc., select the corresponding numerical value, or estimate through such selection, the detected physical numerical value or electrical signal or the selected or estimated numerical value, etc. It is a broad concept encompassing derivation or estimation in accordance with an algorithm, a calculation formula, or the like, or simply acquiring a value detected, selected, estimated or derived as an electrical signal or the like. Therefore, the aspect of acquiring the “first cooling water temperature”, the “second cooling water temperature” and the “cooling water pressure” according to the present invention is not limited to that of the present embodiment.

  Next, the ECU 100 estimates the engine-side boiling reference temperature Tlim1 and the exhaust-side boiling reference temperature Tlim2 that are the above-described boiling reference temperatures (step S102). The engine-side boiling reference temperature Tlim1 is an example of the “first boiling reference temperature” according to the present invention, and the exhaust-side boiling reference temperature Tlim2 is an example of the “second boiling reference temperature” according to the present invention.

  As shown in FIG. 3, the engine-side boiling reference temperature Tlim1 and the exhaust-side boiling reference temperature Tlim2 in the present embodiment are stored in the ROM in a state that can be referred to by the ECU 100 in advance. FIG. 3 is a schematic diagram of a boiling reference temperature map in which the output condition of the engine 200 is associated with the engine-side boiling reference temperature Tlim1 and the exhaust-cooling boiling reference temperature Tlim2. The boiling reference temperature map shown in the figure is a schematic diagram for ease of explanation, and the boiling reference temperature map map is actually stored in the ROM in a state in which the relationship shown in FIG. 3 is quantified. .

  In the boiling reference temperature map, the boiling reference temperature is set by using the output condition of the engine 200, for example, the engine speed or the engine torque as a parameter. However, such an estimation mode of the boiling reference temperature is merely an example, and the ECU 100 estimates the boiling reference temperature without any practical shortage, for example, experimentally, empirically, theoretically, or using simulation in advance. The boiling reference temperature may be calculated individually and specifically each time by appropriately substituting the engine rotational speed or engine torque at that time into an arithmetic expression determined to be possible.

  When the engine-side boiling reference temperature Tlim1 and the exhaust-side boiling reference temperature Tlim2 are estimated, the ECU 100 determines whether or not the engine-side cooling water temperature Thw1 is higher than the engine-side boiling reference temperature Tlim1 (step S103). Here, the engine-side boiling reference temperature Tlim1 allows the boiling of the engine-side cooling water that may be accidentally generated for some reason, and is clearly adapted to determine whether or not the engine-side cooling water is in a boiling state. It is set as a value. That is, when the engine-side cooling water temperature Thw1 is higher than the engine-side boiling reference temperature Tlim1, it can be determined that the engine-side cooling water is in a boiling state. Here, the “boiling state” naturally includes that the cooling water leak has already occurred in the cooling water circulation path 310 at present, but if anything, the boiling of this kind of cooling water causes the leakage of cooling water. This indicates a state where the possibility of occurrence is estimated to be so high that it is difficult to overlook in practice.

  In step S103, when the engine-side cooling water temperature Thw1 is higher than the engine-side boiling reference temperature Tlim1 (step S103: YES), the ECU 100 prohibits the electric WP 320 from stopping, assuming that the cooling water is in a boiling state (step S103). S104). That is, the cooling water circulation by the electric WP 320 is continued or started. The control according to step S104 is an example of the operation of the ECU 100 that functions as the “stop prohibiting means” according to the present invention. Thus, the stop of the electric water pump is prohibited, so that the boiling of the cooling water can be avoided quickly and reliably.

  On the other hand, when engine-side cooling water temperature Thw1 is equal to or lower than engine-side boiling reference temperature Tlim1 (step S103: NO), ECU 100 maintains electric WP 320 in a stopped state, assuming that the cooling water is not in a boiling state, and performs processing. The process proceeds to step S105.

  In step S105, the ECU 100 determines whether or not the exhaust side cooling water temperature Thw2 is higher than the exhaust side boiling reference temperature Tlim2. Here, the exhaust-side boiling reference temperature Tlim2 is, like the engine-side boiling reference temperature Tlim1, to allow the boiling of the exhaust-side cooling water that may occur accidentally for some reason. It is set as a fitness value that can be determined whether or not there is. That is, when the exhaust side cooling water temperature Thw2 is higher than the exhaust side boiling reference temperature Tlim2, it can be determined that the exhaust side cooling water is in a boiling state.

  When the exhaust-side cooling water temperature Thw2 is higher than the exhaust-side boiling reference temperature Tlim2 (step S105: YES), the ECU 100 prohibits the electric WP 320 from stopping, assuming that the cooling water is in a boiling state (step S104).

  On the other hand, when the exhaust-side cooling water temperature Thw2 is equal to or lower than the exhaust-side boiling reference temperature Tlim2 (step S105: NO), the ECU 100 maintains the electric WP 320 in a stopped state or assumes that the electric water WP 320 is not in a boiling state. Is stopped, and the process proceeds to step S106.

  In step S106, the ECU 100 acquires the cooling water system pressure Pw in the cooling water circulation path 310 by the water pressure sensor 390 described above. The control according to step S106 is an example of the operation of the ECU 100 that functions as the “water pressure specifying means” according to the present invention.

  When the system water pressure Pw is acquired, the ECU 100 determines whether or not the acquired system water pressure Pw is greater than the reference value A (step S107). Here, the reference value A is set as a suitable value that can clearly determine whether or not the cooling water is in a boiling state, and is an experimental suitable value as an example of the “pressure threshold” according to the present invention. . That is, when the system water pressure Pw is larger than the reference value A, it can be determined that the cooling water in the cooling water circulation path 310 is in a boiling state. The reference value A is stored in advance in the ROM so that it can be referred to by the ECU 100.

  When the system water pressure Pw is larger than the reference value A (step S107: YES), the ECU 100 has a difference value ΔT1 obtained by subtracting the engine-side cooling water temperature Thw1 from the engine-side boiling reference temperature Tlim1 (that is, Tlim1-Thw1). And a difference value ΔT2 obtained by subtracting the exhaust-side cooling water temperature Thw2 from the exhaust-side boiling reference temperature Tlim2 (that is, Tlim2−Thw2), and whether the calculated difference value ΔT1 is greater than the difference value ΔT2. Is determined (step S108).

  As shown in FIG. 4, when the calculated difference value ΔT1 is larger than the difference value ΔT2 (step S108: YES), the ECU 100 assumes that the exhaust-side cooling water is in a boiling state, and the exhaust-side boiling reference temperature. Tlim2 is updated to the low temperature side (step S109). That is, the ECU 100 corrects the exhaust-side boiling reference temperature Tlim2 by subtracting the correction amount 2 from the exhaust-side boiling reference temperature Tlim2, and also uses the corrected exhaust-side boiling reference temperature Tlim2 for boiling determination of the exhaust-side cooling water. Update as the reference value.

  On the other hand, when the calculated difference value ΔT1 is equal to or less than the difference value ΔT2 (step S108: NO), the ECU 100 updates the engine-side boiling reference temperature Tlim1 to the low-temperature side, assuming that the engine-side cooling water is in a boiling state. (Step S110). That is, the ECU 100 corrects the engine-side boiling reference temperature Tlim1 by subtracting the correction amount 1 from the engine-side boiling reference temperature Tlim1, and also uses the corrected engine-side boiling reference temperature Tlim1 for boiling determination of engine-side cooling water. Update as the reference value.

  Thus, only one of the engine-side boiling reference temperature Tlim1 and the exhaust-side boiling reference temperature Tlim2 that needs to be learned is corrected, which is extremely useful in practice.

  On the other hand, when the system water pressure Pw is equal to or lower than the reference value A (step S107: NO), the ECU 100 assumes that neither the engine-side cooling water nor the exhaust-side cooling water is in a boiling state, and the engine-side boiling reference temperature Tlim1. And the exhaust side boiling reference temperature Tlim2 is updated to the high temperature side (step S111). That is, the ECU 100 corrects the engine-side boiling reference temperature Tlim1 by adding a correction amount 3 to the engine-side boiling reference temperature Tlim1. In parallel with or in parallel with this, the correction amount 4 is added to the exhaust-side boiling reference temperature Tlim2, thereby correcting the exhaust-side boiling reference temperature Tlim2. Further, the corrected engine-side boiling reference temperature Tlim1 and the exhaust-side boiling reference temperature Tlim2 are updated as reference values for determining the boiling of the engine-side and exhaust-side cooling water.

  The control according to Step S109, Step S110, and Step S111 is an example of the operation of the ECU 100 that functions as the “correction unit” according to the present invention. As described above, the engine-side boiling reference temperature Tlim1 and the exhaust-side boiling reference temperature Tlim2 are corrected according to the cooling water system water pressure Pw. The adverse effect on the accuracy of determining the boiling state of the cooling water is alleviated. As a result, the accuracy of determining the boiling state can be favorably ensured, and the margin considering the error in determining the boiling state can be small.

  The modes of the correction amount 1, the correction amount 2, the correction amount 3, and the correction amount 4 are not particularly limited. Each correction amount may be a fixed value set in advance for correction, or the aforementioned engine-side boiling reference temperature Tlim1, exhaust-side boiling reference temperature Tlim2, engine-side cooling water temperature Thw1, exhaust-side cooling water temperature Thw2. , The difference value ΔT1 and the difference value ΔT2 may be variable values depending on the magnitude of the difference, and the value is determined in advance by experimentally, empirically, theoretically, or by simulation. It may be set so as to prevent erroneous determination as much as possible.

  When the engine-side boiling reference temperature Tlim1 and the exhaust-side boiling reference temperature Tlim2 are updated, the process returns to step S103. That is, the ECU 100 learns the boiling reference temperature in accordance with the water pressure even if the engine-side and exhaust-side cooling water temperatures are both lower than the boiling reference temperature, and re-applies the cooling water based on the learned boiling reference temperature. Determine boiling.

  Once it is determined that the cooling water is in a boiling state based on the boiling reference temperature, the stop of the electric WP 320 is prohibited in step S104, the process is returned to step S101, and a series of processes is repeated. The boiling reference temperature correction process is executed in this way.

  Note that “high” and “large” in the boiling reference temperature correction process of the present embodiment are examples of “exceeding” according to the present invention, and the engine-side boiling reference temperature Tlim1, the exhaust-side boiling reference temperature Tlim2, and the reference value. This is a concept that can easily be replaced with “above” depending on the setting of A or the like, and which region the engine-side boiling reference temperature Tlim1, the exhaust-side boiling reference temperature Tlim2, and the reference value A belong to affects the essence of the invention Not give.

  Thus, according to the boiling reference temperature correction process in the present embodiment, the ECU 100 determines that the engine side cooling water temperature Thw1 is higher than the engine side boiling reference temperature Tlim1 or the exhaust side cooling water temperature Thw2 is the exhaust side boiling reference temperature Tlim2. If the temperature is higher than that, the electric water pump 320 is prohibited from being stopped, so that boiling of the cooling water can be avoided quickly and reliably.

  Further, the ECU 100 determines that the system water pressure Pw is greater than the reference value A when the engine-side cooling water temperature Thw1 is equal to or lower than the engine-side boiling reference temperature Tlim1 and the exhaust-side cooling water temperature Thw2 is equal to or lower than the exhaust-side boiling reference temperature Tlim2. Of the engine-side boiling reference temperature Tlim1 and the exhaust-side boiling reference temperature Tlim2, the smaller of the corresponding difference value ΔT1 or difference value ΔT2, that is, only one that needs to be corrected is corrected, which is extremely useful in practice. It is.

  On the other hand, the ECU 100 determines that the system water pressure Pw is equal to or lower than the reference value A when the engine-side cooling water temperature Thw1 is equal to or lower than the engine-side boiling reference temperature Tlim1 and the exhaust-side cooling water temperature Thw2 is equal to or lower than the exhaust-side boiling reference temperature Tlim2. In this case, both the engine-side boiling reference temperature Tlim1 and the exhaust-side boiling reference temperature Tlim2 are corrected to the high temperature side.

  Therefore, by appropriately correcting the engine-side boiling reference temperature Tlim1 and the exhaust-side boiling reference temperature Tlim2 according to the system water pressure Pw, for example, the distinction between the vehicle and the engine 200 or the type of cooling water can be reduced. The adverse effect on the determination accuracy of the boiling state can be mitigated. Therefore, it is possible to favorably ensure the accuracy of determining the boiling state. The margin considering the error in determining the boiling state can be surely reduced.

  In addition, since the boiling state of the cooling water can be determined with high accuracy in this way, the engine system 10 can accurately execute the electric WP stop control during the electric WP 320 stop period. Therefore, it is possible to maximize the practical benefits related to both avoidance of boiling of cooling water and reduction in fuel consumption by this electric WP stop control.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification. Cooling of an internal combustion engine accompanying such a change is possible. The control device of the apparatus is also included in the technical scope of the present invention.

  The control device for a cooling device for an internal combustion engine according to the present invention can be used as a control device for controlling the cooling device for the internal combustion engine in various vehicles such as ordinary vehicles and hybrid vehicles.

  DESCRIPTION OF SYMBOLS 10 ... Engine system, 100 ... ECU, 200 ... Engine, 300 ... Cooling part, 310 ... Cooling water circulation path, 310a ... Engine cooling circulation path, 310b ... Radiator bypass path, 310c ... Exhaust cooling path, 320 ... Electric WP, 330 ... Radiator, 340 ... Thermostat, 350 ... Heater core, 360 ... Exhaust heat recovery device, 370 ... Engine side cooling water temperature sensor, 380 ... Exhaust side cooling water temperature sensor, 390 ... Water pressure sensor.

Claims (1)

A control device for controlling the stop of the electric water pump in an internal combustion engine and a cooling device capable of cooling the exhaust discharged from the internal combustion engine by circulating cooling water by an electric water pump,
First temperature specifying means for specifying a first cooling water temperature as a temperature of an internal combustion engine cooling portion for cooling the internal combustion engine in the cooling water;
A second temperature specifying means for specifying a second cooling water temperature as a temperature of an exhaust cooling portion for cooling the exhaust of the cooling water;
Water pressure specifying means for specifying the water pressure of the cooling water;
When the specified first cooling water temperature exceeds a currently set first boiling reference temperature, or when the specified second cooling water temperature exceeds a currently set second boiling reference temperature. Stop prohibiting means for prohibiting the stop of the electric water pump;
The specified first cooling water temperature does not exceed the currently set first boiling reference temperature, and the specified second cooling temperature exceeds the currently set second boiling reference temperature. (B) if the specified water pressure exceeds a pressure threshold set in advance as a pressure corresponding to the boiling state, the first boiling reference temperature and the second boiling reference temperature (B) If the specified water pressure does not exceed the pressure threshold value, the smaller one of the difference from the first or second cooling water temperature is corrected to the low temperature side. And a correction means for correcting at least one of the two boiling reference temperatures to a high temperature side.

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