Cooling control device for internal combustion engine

Abstract

To provide a cooling control device for an internal combustion engine capable of effectively suppressing a high temperature state that easily induces knocking during an operation in a high-load region of the internal combustion engine and thus suppressing execution of timing delay control.SOLUTION: A cooling control device 1 for an internal combustion engine includes: a cooling circuit 3 for cooling the internal combustion engine 2 by using cooling water; and an electric water pump 4 connected to the cooling circuit 3 to circulate the cooling water in the cooling circuit 3. The cooling control device further includes: water temperature acquisition means for acquiring a water temperature of the cooling water; speed acquisition means for acquiring speed NE of the internal combustion engine 2; predicted load estimation means for estimating predicted load that is future load of the internal combustion engine 2; and pump control means for driving the electric water pump 4 with output corresponding to the acquired speed NE when the acquired water temperature is a predetermined first threshold value or greater and the estimated predicted load is a predetermined second threshold value or greater.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a cooling control device for an internal combustion engine that controls the cooling of the internal combustion engine by controlling the flow rate of coolant circulating through a cooling circuit. [Background technology]

[0002] In recent years, research and development has been conducted into improving fuel efficiency, which contributes to energy efficiency, in order to ensure that more people have access to affordable, reliable, sustainable and advanced energy.

[0003] Generally, in internal combustion engines installed in vehicles such as automobiles, the possibility of knocking increases when the temperature in the combustion chamber rises due to driving in a high load range, etc. Therefore, when the refrigerant (cooling water) that cools the internal combustion engine becomes hot, the ignition timing of the internal combustion engine is controlled to be retarded from the optimal ignition timing at which maximum torque is obtained, thereby reducing the pressure in the combustion chamber and suppressing the occurrence of knocking.

[0004] For example, Patent Document 1 discloses a technology that prevents abnormal combustion by controlling the ignition timing of an internal combustion engine to retard it when knocking is detected during control to advance the ignition timing, and also controlling the water pump to increase the flow rate of the cooling water. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-116310 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the conventional technology has the following problem. That is, when the engine is operated in a high load range, if the engine coolant temperature becomes high and control is executed to retard the ignition timing, the fuel economy deteriorates. To prevent the deterioration of fuel economy, it is necessary to effectively prevent the engine from reaching a high temperature that easily induces knocking when the engine is operated in a high load range, thereby avoiding the execution of the retard control as much as possible.

[0007] The present invention has been made to solve the above problems, and aims to provide a cooling control device for an internal combustion engine that can effectively prevent a high temperature state that is likely to induce knocking when the internal combustion engine is operating in a high load range, thereby suppressing the execution of retard control, and ultimately contributing to energy efficiency. [Means for solving the problem]

[0008] In order to achieve this object, the invention according to claim 1 of the present invention is a cooling control device for an internal combustion engine of a vehicle, the cooling control device having a cooling circuit 3 that cools an internal combustion engine (an engine 2 in an embodiment (hereinafter the same in this paragraph)) with cooling water, and an electric water pump 4 connected to the cooling circuit 3 and circulating the cooling water through the cooling circuit 3, the cooling control device including water temperature acquisition means (a first water temperature sensor 6, a second water temperature sensor 7) that acquires the water temperature (a first water temperature Tw1, a second water temperature Tw2) of the cooling water, and a rotational speed NE of the internal combustion engine. a water temperature acquisition means (rotation speed sensor 13), a predicted load estimation means (ECU 10, predicted load estimation unit 11) for estimating a predicted load, which is a future load of the internal combustion engine, and a pump control means (ECU 10, pump control unit 12) for driving the electric water pump 4 with an output corresponding to the acquired rotation speed NE (steps 302, 313, 319 in FIG. 3) when the acquired water temperature is equal to or higher than a predetermined first threshold value (second threshold water temperature Tref2) and the estimated predicted load is equal to or higher than a predetermined second threshold value; an accelerator opening degree acquisition means for acquiring an accelerator opening degree of a vehicle; Equipped with The predicted load estimation means calculates a required output of the vehicle based on the acquired accelerator opening and the acquired rotation speed, and calculates an average value of the required output calculated within a recent predetermined time period as a predicted load. It is characterized by the following.

[0009] According to this cooling control device for an internal combustion engine, when both the coolant temperature and the predicted load of the internal combustion engine are equal to or greater than a predetermined threshold, the pump control means drives the electric water pump at an output corresponding to the engine speed. Therefore, under circumstances where the operating state of the internal combustion engine is predicted to be in a predetermined high-load range and the coolant temperature is high, predicting the occurrence of knocking in the near future, by driving the electric water pump at an output corresponding to the engine speed, the coolant temperature can be lowered and the pressure in the combustion chamber can be reduced before knocking occurs.

[0010] Although there is a certain time lag between when the electric water pump is driven and when the coolant temperature actually decreases, as described above, by driving the electric water pump in advance when a situation in which knocking is predicted to occur, rather than after the occurrence of knocking is confirmed, it is possible to effectively prevent the coolant from reaching a high temperature that would induce knocking. Therefore, according to the present invention, it is possible to effectively prevent the coolant from reaching a high temperature that would easily induce knocking when the internal combustion engine is operating in a high load range, thereby suppressing the execution of the ignition retard control and improving fuel efficiency.

[0012] Also The predicted load estimation means calculates the average value of the vehicle's required output calculated within the most recent specified time period as the predicted load, and the pump control means drives the electric water pump at an output corresponding to the internal combustion engine's rotation speed when both the coolant temperature and the average value of the vehicle's required output are equal to or greater than a specified threshold.When driving the electric water pump to cool the internal combustion engine, it is important to predict the predicted load of the internal combustion engine with high accuracy to prevent excessive cooling from worsening fuel efficiency.In this configuration, focusing on the fact that operating conditions have a certain degree of continuity, the average value of the required output within the most recent specified time period is calculated as the predicted load, thereby enabling the predicted load to be estimated with high accuracy.

[0013] Therefore, with this configuration, when the operating state of the internal combustion engine is predicted to be in a predetermined high load range and the coolant temperature reaches a predetermined high temperature, knocking is predicted to occur in the near future, and by driving the electric water pump with an output corresponding to the engine speed, the coolant temperature can be lowered in advance and the pressure in the combustion chamber can be reduced. This effectively prevents the high temperature condition that is likely to induce knocking when the internal combustion engine is operating in a high load range, thereby suppressing the execution of retard control and improving fuel efficiency.

[0014] Claims of the invention 2 The invention relating to A cooling control device for an internal combustion engine of a vehicle having a cooling circuit 3 that cools an internal combustion engine (engine 2) with coolant, and an electric water pump 4 connected to the cooling circuit 3 and circulating the coolant through the cooling circuit 3, the cooling control device comprising: water temperature acquisition means (first water temperature sensor 6, second water temperature sensor 7) that acquires the temperature of the coolant (first water temperature Tw1, second water temperature Tw2); rotation speed acquisition means (rotation speed sensor 13) that acquires the rotation speed NE of the internal combustion engine; predicted load estimation means (ECU 10, predicted load estimation unit 11) that estimates a predicted load that is a future load on the internal combustion engine; and pump control means (ECU 10, pump control unit 12) that drives the electric water pump 4 with an output corresponding to the acquired rotation speed NE when the acquired water temperature is equal to or higher than a predetermined first threshold (second threshold water temperature Tref2) and the estimated predicted load is equal to or higher than a predetermined second threshold (steps 302, 313, 319 in FIG. 3 ); The pump control means is characterized in that, if the predicted load falls below the second threshold value after driving the electric water pump 4, it maintains driving of the electric water pump 4 until a predetermined drive maintenance time has elapsed (steps 315 and 316 in Figure 3).

[0015] According to this configuration, if the predicted load falls below a predetermined threshold after the electric water pump is driven under high-load and high-water-temperature conditions, i.e., even if a low-load operation state is predicted in the near future, the electric water pump will continue to be driven until a predetermined time has elapsed. When the internal combustion engine's operating state transitions from high to low load, the coolant temperature is expected to gradually decrease accordingly. However, there is a certain time lag between the transition to low-load operation and the start of the decrease in coolant temperature. As described above, this configuration maintains the electric water pump's operation until the predetermined time has elapsed, thereby improving the responsiveness of the rate at which the coolant temperature decreases when the engine transitions from high-load operation to low-load operation.

[0016] Claims of the invention 3The invention according to claim 1 is characterized in that, in the cooling control device for an internal combustion engine, it further comprises an outside air temperature parameter acquisition means (first water temperature sensor 6, second water temperature sensor 7) for acquiring an outside air temperature parameter representing the temperature of the outside air, and the pump control means reduces the output of the electric water pump 4 when the acquired outside air temperature parameter (water temperature difference ΔTw) is equal to or greater than a predetermined fourth threshold value (steps 817, 811 in Figure 8).

[0017] According to this configuration, the pump control means reduces the output of the electric water pump when the outside air temperature parameter is equal to or higher than a predetermined threshold. When the outside air temperature is high, the heat dissipation efficiency of the coolant decreases, making it difficult to lower the coolant temperature. In such cases, even if the electric water pump is driven at high output, the expected cooling effect on the internal combustion engine may not be achieved, and the deterioration of electricity consumption may outweigh the improvement in fuel economy. According to this configuration, by suppressing the output of the electric water pump under such high outside air temperature conditions, the deterioration of electricity consumption can be prevented.

[0018] Claims of the invention 4 The invention relating to A cooling control device for an internal combustion engine of a vehicle having a cooling circuit 3 that cools an internal combustion engine (engine 2) with coolant, and an electric water pump 4 connected to the cooling circuit 3 and circulating the coolant through the cooling circuit 3, the cooling control device comprising: water temperature acquisition means (first water temperature sensor 6, second water temperature sensor 7) that acquires the temperature of the coolant (first water temperature Tw1, second water temperature Tw2); rotation speed acquisition means (rotation speed sensor 13) that acquires the rotation speed NE of the internal combustion engine; predicted load estimation means (ECU 10, predicted load estimation unit 11) that estimates a predicted load that is a future load on the internal combustion engine; and pump control means (ECU 10, pump control unit 12) that drives the electric water pump 4 with an output corresponding to the acquired rotation speed NE when the acquired water temperature is equal to or higher than a predetermined first threshold (second threshold water temperature Tref2) and the estimated predicted load is equal to or higher than a predetermined second threshold (steps 302, 313, 319 in FIG. 3 ); A radiator 5 for cooling the coolant is connected to the cooling circuit, and the water temperature acquisition means acquires the water temperature downstream of the internal combustion engine in the cooling circuit as a first water temperature Tw1 and the water temperature downstream of the radiator 5 as a second water temperature Tw2, and the pump control means reduces the output of the electric water pump 4 when the difference between the first water temperature Tw1 and the second water temperature Tw2 (water temperature difference ΔTw) is below a predetermined fifth threshold value (threshold value Tref) (steps 817 and 811 in Figure 8).

[0019] According to this configuration, the pump control means reduces the output of the electric water pump when the difference between the first water temperature and the second water temperature falls below a predetermined threshold. When the outside air temperature is high, the efficiency of heat dissipation of the coolant by the radiator may decrease, making it difficult to lower the coolant temperature. In such cases, the difference between the coolant temperature immediately after passing through the internal combustion engine and the coolant temperature immediately after passing through the radiator becomes small. In such cases, even if the electric water pump is driven at high output, the expected cooling effect for the internal combustion engine may not be achieved, and the deterioration of electricity consumption may outweigh the improvement in fuel consumption. According to this configuration, by suppressing the output of the electric water pump when the radiator's cooling effect on the coolant is reduced, the deterioration of electricity consumption can be prevented.

[0020] Claims of the invention 5 The invention according to the present invention is characterized in that, in the cooling control device for an internal combustion engine as described in claim 1, it further comprises a map information acquisition means for acquiring map information MI, and the predicted load estimation means estimates the predicted load based on the acquired map information MI (steps 913, 914 in Figure 9, Figure 10).

[0021] According to this configuration, the predicted load estimation means estimates the predicted load based on map information, and the pump control means drives the electric water pump at an output corresponding to the engine speed when both the coolant temperature and the predicted internal combustion engine load are equal to or higher than predetermined thresholds. Therefore, under circumstances where the internal combustion engine is predicted to be operating in a predetermined high-load range and the coolant temperature is predicted to reach a predetermined high temperature, thereby predicting the occurrence of knocking in the near future, the electric water pump is driven at an output corresponding to the engine speed, thereby lowering the coolant temperature and reducing the pressure in the combustion chamber. This effectively prevents the internal combustion engine from reaching a high temperature that is likely to induce knocking when operating in a high-load range, thereby suppressing the execution of retard control and improving fuel economy. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a diagram showing a schematic configuration of a cooling control device for an internal combustion engine according to an embodiment of the present invention, together with the internal combustion engine; [Figure 2] 1 is a block diagram showing the configuration of a control system of a cooling control device for an internal combustion engine according to an embodiment of the present invention; [Figure 3] 3 is a flowchart showing a cooling control process for an internal combustion engine according to one embodiment of the present invention. [Figure 4] 10 is a table (base table) showing the relationship between the rotation speed of the internal combustion engine and the rotation speed of the electric water pump after warm-up is complete. [Figure 5] 10 is a table (pre-cooling table) showing the relationship between the rotation speed of the internal combustion engine and the rotation speed of the electric water pump during execution of pre-cooling control. [Figure 6] 10 is a table (high water temperature table) showing the relationship between the rotation speed of the internal combustion engine and the rotation speed of the electric water pump when the water temperature is high. [Figure 7] 10 is a timing chart showing an example of an operation when switching between normal control and pre-cooling control. [Figure 8] 10 is a flowchart showing a cooling control process for an internal combustion engine according to another embodiment. [Figure 9] 10 is a flowchart showing a cooling control process for an internal combustion engine according to another embodiment. [Figure 10] 10 is a flowchart showing a terrain determination control process. DETAILED DESCRIPTION OF THE INVENTION

[0023] A preferred embodiment of the present invention will be described in detail below with reference to the drawings. Fig. 1 shows a cooling control device 1 for an internal combustion engine according to one embodiment of the present invention, together with an internal combustion engine (hereinafter referred to as "engine") 2. The engine 2 of this embodiment is provided as a power source in a hybrid vehicle (hereinafter referred to as "vehicle"). In addition to the engine 2, this vehicle is also provided with an electric motor (hereinafter referred to as "motor") (not shown) as a power source, and either the engine 2 or the motor, or both, are used as the power source for the vehicle depending on the running state of the vehicle.

[0024] As shown in FIG. 1, a cooling circuit 3 for cooling the engine 2 is connected to the engine 2. The cooling circuit 3 is a circuit that passes through an electric water pump (hereinafter referred to as "EWP") 4 and a radiator 5, and is filled with coolant. The coolant is sent out by the EWP 4 to circulate within the cooling circuit 3, cools the engine 2 by exchanging heat with the engine 2, and releases heat to the outside by exchanging heat with the radiator 5. The cooling circuit 3 is also provided with a thermostat 8, which switches the coolant passage (a passage that passes through the radiator 5 and a passage that does not) depending on the coolant temperature, thereby stably maintaining the coolant temperature within a predetermined temperature range (for example, 75 to 85°C).

[0025] The EWP 4 is driven by an actuator (motor) supplied with power from a battery (not shown) or the like, and circulates the coolant through the cooling circuit 3 by rotating an impeller built into it. When the rotation speed of the impeller of the EWP 4 (hereinafter referred to as "EWP rotation speed") increases, the flow rate of the circulating coolant increases, thereby improving the cooling effect on the engine 2. The actuator of the EWP 4 is driven under the control of the ECU 10, which will be described later. In other words, the operation of the EWP 4 is controlled by the ECU 10.

[0026] A first water temperature sensor 6 is provided downstream of the engine 2 in the cooling circuit 3, and a second water temperature sensor 7 is provided downstream of the radiator 5. The first and second water temperature sensors 6, 7 detect the temperatures of the coolant at their respective installation positions as a first water temperature Tw1 and a second water temperature Tw2, respectively. Detection signals from these sensors are output to the ECU 10.

[0027] 2 shows the configuration of a control system of the cooling control device 1 according to this embodiment. The ECU 10 is configured as a microcomputer including a CPU, RAM, ROM, and an I / O interface (none of which are shown). In addition to the first water temperature sensor 6 and second water temperature sensor 7 described above, the ECU 10 is connected to a rotation speed sensor 13 that detects the rotation speed NE of the engine 2, an accelerator opening sensor 14 that detects the amount of operation of the accelerator pedal of the vehicle (accelerator opening AP), and other sensors, and these detection signals are input sequentially.

[0028] The ECU 10 implements the functions of a predictive load estimation unit 11 and a pump control unit 12 by reading and executing programs stored in the ROM or RAM. The predictive load estimation unit 11 calculates the current required output PRQ of the vehicle based on the detected engine speed NE and accelerator opening AP of the engine 2. As will be described later, when a predetermined water temperature condition is satisfied, the predictive load is calculated as an average value PRQM of the required outputs PRQ calculated within a predetermined most recent period, which is the near future load of the engine 2. As will be described later, the pump control unit 12 controls the operation of the EWP 4 in accordance with the predicted load estimated by the predictive load estimation unit 11 and detection signals from the various sensors described above, thereby performing cooling control of the engine 2.

[0029] The operation of the cooling control device 1 according to this embodiment configured as described above will be described with reference to Figures 3 to 7. The cooling control device 1 according to this embodiment controls the drive of the EWP 4 mainly according to the coolant temperature (first coolant temperature Tw1) in accordance with a total of four types of maps and tables (cold state map, warm-up state table, pre-cooling table, and high coolant temperature table).

[0030] FIG. 3 is a flowchart showing the cooling control process according to this embodiment. This process is repeatedly executed at predetermined time intervals while the engine 2 is in a normal operating state. In this process, first, in step 301 (denoted as "S301"; the same applies below), it is determined whether a first water temperature Tw1, which is the water temperature downstream of the engine 2, is lower than a predetermined first threshold water temperature Tref1. The first threshold water temperature Tref1 is set as a high water temperature at which the coolant needs to be cooled immediately if the first water temperature Tw1 is equal to or higher than this temperature. In this embodiment, the first threshold water temperature Tref1 is set to, for example, 98°C.

[0031] If the determination result in step 301 is YES, that is, if the detected first water temperature Tw1 is lower than the first threshold water temperature Tref1, the process proceeds to step 302. In step 302, it is determined whether the first water temperature Tw1 is lower than a predetermined second threshold water temperature Tref2. If the first water temperature Tw1 is equal to or higher than this temperature, the second threshold water temperature Tref2 is set as a high water temperature at which it is determined that knocking is highly likely to be induced when the vehicle is running under high load. In this embodiment, the second threshold water temperature Tref2 is set to, for example, 85°C.

[0032] If the determination result in step 302 is YES, that is, if the detected first water temperature Tw1 is lower than the second threshold water temperature Tref2, the process proceeds to step 303. In step 303, it is determined whether the first water temperature Tw1 is lower than a predetermined third threshold water temperature Tref3. The third threshold water temperature Tref3 is set as a water temperature at which it is determined that the engine has warmed up if the first water temperature Tw1 is equal to or higher than this temperature. In this embodiment, the third threshold water temperature Tref3 is set to, for example, 75°C.

[0033] If the determination result in step 303 is YES, that is, if the detected first water temperature Tw1 is lower than the third threshold water temperature Tref3, it is determined that the warm-up of the engine 2 has not yet been completed, and the process proceeds to step 304. In step 304, the value of a pre-cooling control continuation timer, which will be described later, is reset, and then the process proceeds to step 305. In step 305, the value of a required output average value calculation flag F_PRQM, which will be described later, is set to "0." Next, the process proceeds to step 306, where the value of a pre-cooling control execution flag F_pre-cooling control, which will be described later, is set to "0," and then the process proceeds to step 307.

[0034] In step 307, the pump control unit 12 of the ECU 10 searches a cold-state map (not shown) to control the drive of the EWP 4, and then this process ends. The cold-state map can determine the EWP rotation speed based on, for example, the rotation speed NE of the engine 2 and the intake air amount. Since the cold-state map is used when the water temperature is low before the engine 2 has completely warmed up, the EWP rotation speed is suppressed so as not to hinder early warming up of the engine 2.

[0035] On the other hand, if the determination result in step 303 is NO, that is, if the detected first water temperature Tw1 is equal to or higher than the third threshold water temperature Tref3, it is determined that the warm-up of the engine 2 has been completed, and the process proceeds to step 308. In step 308, the value of a required output average value calculation flag F_PRQM (described later) is set to "0," and then the process proceeds to step 309. In step 309, the value of a pre-cooling control continuation timer (described later) is reset. Next, the process proceeds to step 310, where the value of a pre-cooling control execution flag F_pre-cooling control (described later) is set to "0," and then the process proceeds to step 311.

[0036] In step 311, the pump control unit 12 of the ECU 10 searches the base table shown in Figure 4 to execute normal control for controlling the drive of the EWP 4, and then this process ends. The base table determines the EWP rotation speed according to the rotation speed NE of the engine 2, and is set so that when the rotation speed NE exceeds a predetermined value, the EWP rotation speed increases as the rotation speed NE increases. This normal control is executed with the aim of maintaining the coolant temperature within a predetermined temperature range (e.g., 75 to 85°C).

[0037] Next, if the determination result in step 302 is NO, that is, if the detected first water temperature Tw1 is equal to or higher than the second threshold water temperature Tref2, it is determined that there is a high possibility that knocking will be induced when the vehicle is running under high load, and the process proceeds to step 312. In step 312, the value of the required output average value calculation flag F_PRQM is set to "1." This causes the predicted load estimation unit 11 of the ECU 10 to start estimating a predicted load, which is the load on the engine 2 in the near future. Specifically, the average value PRQM of the vehicle's required output PRQ calculated within the most recent predetermined time period (for example, 10 seconds) is calculated as the predicted load on the engine 2.

[0038] Next, in step 313, it is determined whether the calculated required power average value PRQM is equal to or greater than a predetermined threshold power Pref. The threshold power Pref can be set to an arbitrary high required power value. In this embodiment, the threshold power Pref is set to, for example, 20 kW.

[0039] If the determination result in step 313 is YES, that is, if the required output average value PRQM is equal to or greater than the threshold output Pref, it is determined that there is a high possibility that knocking will be induced in the engine 2, and the process proceeds to step 317. In step 317, the value of a pre-cooling control continuation timer, which will be described later, is reset. Next, the process proceeds to step 318, where the value of a pre-cooling control execution flag F_pre-cooling control is set to "1", and then the process proceeds to step 319. The pre-cooling control execution flag F_pre-cooling control is set to "1" when drive control of the EWP 4 is executed based on a pre-cooling table, which will be described later.

[0040] In step 319, the pump control unit 12 of the ECU 10 executes pre-cooling control to control the operation of the EWP 4 by searching the pre-cooling table shown in Figure 5, and then this process ends. In Figure 5, for comparison, the values ​​of the base table shown in Figure 4 are indicated by a dashed line. Like the base table, the pre-cooling table determines the EWP rotation speed according to the rotation speed NE of the engine 2. However, compared to the base table, the pre-cooling table is set so that the EWP rotation speed is maintained at a certain level or higher even at low rotation speeds NE, and so that the EWP rotation speed increases at a greater rate as the rotation speed NE increases.

[0041] As described above, pre-cooling control is executed when the coolant temperature is high and the predicted load is large, that is, when it is determined that knocking is likely to occur in the engine 2 in the near future. Therefore, compared to the base table, the pre-cooling table is set so that the EWP rotation speed is higher across the entire range of rotation speed NE, thereby achieving a greater cooling effect on the engine 2. This quickly reduces the temperature in the combustion chamber of the engine 2 and prevents knocking from occurring, thereby reducing the number of times retard control is executed to avoid knocking and contributing to improved fuel economy.

[0042] Next, a case where the determination result in step 313 is NO will be described. If the determination result in step 313 is NO, that is, if the required output average value PRQM is lower than the threshold output Pref, it is determined that the vehicle is not running under high load, and the process proceeds to step 314. In step 314, it is determined whether the value of the pre-cooling control execution flag F_pre-cooling control is "1". This determines whether the cooling control performed immediately before was pre-cooling control using the pre-cooling table. If the determination result in step 314 is NO, that is, the cooling control performed immediately before was not pre-cooling control, the process proceeds to step 311 via step 309 and step 310, where the drive of the EWP 4 is controlled using the base table, and the process ends.

[0043] On the other hand, if the determination result in step 314 is YES and the cooling control performed immediately before was pre-cooling control, it can be determined that the operating state of the engine 2 has just shifted from high load to low load, so the coolant temperature is quickly lowered by continuing to maintain pre-cooling control until a predetermined pre-cooling control duration time has elapsed in the subsequent steps 315 and 316. This makes it possible to improve the responsiveness of the water temperature lowering speed when the engine 2 shifts from high load operation to low load operation.

[0044] A pre-cooling control duration timer is started to determine whether the pre-cooling control duration has elapsed in step 315. The pre-cooling control duration is set to, for example, 10 seconds, and the pre-cooling control duration timer can measure the set time (10 seconds) by counting down.

[0045] In step 316, it is determined whether the value of the pre-cooling control duration timer is equal to or less than 0. If the result of this determination is NO, it is determined that the pre-cooling control duration has not yet elapsed, and the process proceeds via step 318 to step 319, where pre-cooling control is executed, and the process ends.

[0046] On the other hand, if the determination result in step 316 is YES, it is determined that the pre-cooling control duration has elapsed, and the process proceeds to step 311 via step 310, where normal control is executed, and the process ends.

[0047] Next, a case where the determination result in step 301 is NO will be described. If the determination result in step 301 is NO, that is, if the detected first water temperature Tw1 is equal to or higher than the first threshold water temperature Tref1, it is determined that the coolant is in a high temperature state that requires immediate cooling, and the process proceeds to step 320. In step 320, the value of the pre-cooling control continuation timer is reset, and then the process proceeds to step 321. In step 321, the value of the required output average value calculation flag F_PRQM is set to "0." Next, the process proceeds to step 322, where the value of the pre-cooling control execution flag F_pre-cooling control is set to "0," and then the process proceeds to step 323.

[0048] In step 323, the pump control unit 12 of the ECU 10 executes high water temperature control, searching the high water temperature table shown in FIG. 6 to control the operation of the EWP 4, and then this process ends. In FIG. 6, for comparison, the values ​​of the pre-cooling table shown in FIG. 5 are indicated by a dashed line. Like the base table and the pre-cooling table, the high water temperature table determines the EWP rotation speed according to the rotation speed NE of the engine 2. However, compared to the pre-cooling table, the high water temperature table is set so that the EWP rotation speed becomes closer to the maximum from a lower rotation speed NE. This maximizes the flow rate of the coolant, thereby promoting cooling of the coolant and achieving a greater cooling effect for the engine 2.

[0049] Next, an example of operation when switching between normal control and pre-cooling control will be described with reference to Fig. 7. The timing chart in Fig. 7 shows an example of operation of each part when transitioning from normal control to pre-cooling control and from pre-cooling control to normal control. The EV mode flag F_EV is a flag that indicates switching between the engine 2 and the motor as the power source of the vehicle; when the EV mode flag F_EV is "1", the motor is used as the power source, and when it is "0", the engine 2 is used as the power source.

[0050] At time t0 in the figure, the EV mode flag F_EV is "1," and the motor is being used as the power source for the vehicle. At this time, the first water temperature Tw1 is lower than the second threshold water temperature Tref2, and normal control is being executed for the EWP4. Thereafter, when the EV mode flag F_EV becomes "0" and the engine 2 begins to be used as a power source, the rotation speed NE increases, and the first water temperature Tw1 also begins to increase.

[0051] Thereafter, at the timing (time t1) when the first water temperature Tw1 becomes equal to or higher than the second threshold water temperature Tref2, a determination is started as to whether the required output average PRQM has exceeded the threshold output Pref. Thereafter, as the required output average PRQM rises, at the timing (time t2) when PRQM≧Pref is established, the pre-cooling control execution flag F_pre-cooling control is set to “1” and pre-cooling control is executed, thereby increasing the EWP rotation speed. Note that dashed lines indicate imaginary lines that show changes in the EWP rotation speed and the first water temperature Tw1 between times t2 and t7 when normal control is continued without executing pre-cooling control. Execution of pre-cooling control increases the EWP rotation speed more than in the case of normal control, thereby gradually decreasing the first water temperature Tw1.

[0052] Then, at time t3, the EV mode flag F_EV becomes "1" again, and when the motor begins to be used as a power source, the rotation speed NE becomes 0, but the EWP 4 continues to be driven by pre-cooling control. After that, the required output average value PRQM decreases, and at the timing (time t4) when PRQM≧Pref is no longer satisfied, the pre-cooling control continuation timer begins counting down. After that, at the timing (time t5) when the predetermined pre-cooling control duration (10 seconds) has elapsed, the pre-cooling control execution flag F_pre-cooling control is set to "0," and pre-cooling control ends and switches to normal control.

[0053] After that, the required output average value PRQM rises again, and at time t6, when PRQM≧Pref is again established, the EV mode flag F_EV is switched to "0" at the same timing, and the engine 2 begins to be used as a power source. At this time, the first water temperature Tw1 is still equal to or higher than the second threshold water temperature Tref2, and PRQM≧Pref is established, so the pre-cooling control execution flag F_pre-cooling control is again set to "1", pre-cooling control is executed, and at the same time the pre-cooling control continuation timer is reset.

[0054] Next, at time t7, the first water temperature Tw1 falls below the second threshold water temperature Tref2, so the pre-cooling control execution flag F_pre-cooling control is set to "0", and the control shifts from pre-cooling control to normal control.

[0055] As described above, according to the cooling control device 1 of this embodiment, when the first water temperature Tw1 is equal to or higher than the second threshold water temperature Tref2 and the vehicle required output average value PRQM calculated as the future load of the engine 2 is equal to or higher than the threshold output Pref, pre-cooling control is executed to drive the EWP 4 at an output higher than that of normal control in accordance with the rotational speed NE of the engine 2. As a result, in an operating state of "high water temperature, high load" where knocking is likely to occur in the engine 2 in the near future, the temperature of the coolant is lowered to cool the engine 2 and reduce the pressure in the combustion chamber before knocking occurs.

[0056] In this way, by accurately predicting that an operating state in which knocking will be induced will occur in the near future, rather than after the actual occurrence of knocking is confirmed, and executing pre-cooling control in which the EWP 4 is driven at a higher rotation speed in advance, it is possible to prevent the engine 2 from reaching a high temperature state in which knocking will be induced due to a rise in the coolant temperature, thereby avoiding a situation in which it becomes necessary to execute retard control for the engine 2. Therefore, by using the cooling control device 1 of this embodiment, it is possible to effectively prevent the engine 2 from reaching a high temperature state in which knocking is likely to be induced when the engine 2 is operating in a high load range, thereby suppressing the execution of retard control and improving fuel economy.

[0057] Furthermore, if the required output average value PRQM, which is the predicted load of the engine 2, falls below the threshold output Pref after the execution of the pre-cooling control has started, the execution of the pre-cooling control is continued until a predetermined pre-cooling control duration has elapsed, thereby quickly lowering the coolant temperature. This improves the responsiveness of the coolant temperature lowering speed when the engine 2 transitions from high load operation to low load operation.

[0058] Next, a cooling control device 21 according to a second embodiment of the present invention will be described with reference to Fig. 8. The configuration of the cooling control device 21 is similar to that of the cooling control device 1 of the above-described embodiment, but the cooling control according to the second embodiment differs from the above-described embodiment in the determination process before pre-cooling control is executed. This will be described in detail below.

[0059] The control processing from step 801 to step 812 in Fig. 8 is similar to the control processing from step 301 to step 312 in Fig. 3, but the second embodiment is characterized in that if the result of the determination in step 813 as to whether or not the required output average PRQM is equal to or greater than the threshold output Pref is YES, then a determination is made in step 817 as to whether or not the water temperature difference ΔTw is lower than a predetermined threshold value Tref. Here, the water temperature difference ΔTw is a parameter defined as the difference between the first water temperature Tw1 and the second water temperature Tw2.

[0060] As described above, the first water temperature Tw1 is the water temperature downstream of the engine 2, and the second water temperature Tw2 is the water temperature downstream of the radiator 5. During normal operation, the first water temperature Tw1 is the water temperature immediately after heat exchange with the high-temperature engine 2, and the second water temperature Tw2 is the water temperature immediately after heat exchange with the radiator 5, which releases heat to the outside. Therefore, the first water temperature Tw1 is higher than the second water temperature Tw2. Therefore, the water temperature difference ΔTw defined as "Tw1 - Tw2" is a relatively large value. However, when the outside air temperature is high, for example, the heat dissipation efficiency of the radiator 5 decreases and it becomes difficult to lower the temperature of the coolant. This causes the second water temperature Tw2 to become high, and the difference between the first water temperature Tw1 and the second water temperature Tw2 becomes small, resulting in a relatively small value of the water temperature difference ΔTw.

[0061] In such a case, even if the EWP 4 is driven at a high output and the coolant flow rate is increased, the expected cooling effect for the engine 2 may not be obtained, and knocking may not be prevented. Therefore, in such a case, even if the pre-cooling control is performed, improvement in fuel economy cannot be expected, and it is expected that the deterioration in electricity economy may actually be significant. Therefore, in this embodiment, a step of determining whether the water temperature difference ΔTw is lower than the threshold value Tref is added in step 817, so that the pre-cooling control is performed only when the effect of the pre-cooling control is expected. Here, the threshold value Tref is set to a value at which it can be determined that, when the water temperature difference ΔTw is lower than this value, the heat dissipation efficiency of the coolant has decreased and the effect of the pre-cooling control is small.

[0062] If the result of the determination in step 817 is NO, it is determined that the cooling effect of the cooling water is being exerted as usual and that the effect of executing pre-cooling control can be expected. Then, the process proceeds to step 820 via steps 818 and 819, which are the same processes as steps 317 and 318 in Figure 3, and pre-cooling control is executed in the same way as step 319 in Figure 3, and this process ends.

[0063] On the other hand, if the determination result in step 817 is YES, it is determined that the cooling effect of the cooling water has decreased and the effect of executing pre-cooling control is small, and the process proceeds to step 814. In step 814, similar to step 314 in Fig. 3, it is determined whether the cooling control performed immediately before was pre-cooling control using a pre-cooling table. If the determination result in step 814 is NO, that is, the cooling control performed immediately before was not pre-cooling control, the process proceeds to step 811 via step 809 and step 810, where the drive of EWP 4 is controlled using the base table, and this process ends.

[0064] Furthermore, if the determination result in step 814 is YES and the cooling control performed immediately before is pre-cooling control, the same processing as steps 315 and 316 in FIG. 3 is performed in steps 815 and 816, and after a predetermined duration of pre-cooling control has elapsed, the process proceeds to step 811 via step 810, where the drive of EWP4 is controlled using the base table, and this process ends.

[0065] As described above, according to the cooling control device 21 of this embodiment, even if the first water temperature Tw1 is equal to or higher than the second threshold water temperature Tref2 and the vehicle required output average value PRQM calculated as the future load of the engine 2 is equal to or higher than the threshold output Pref, if the water temperature difference ΔTw is below the threshold Tref, it is determined that the cooling effect of the coolant has become small due to factors such as high outside air temperature, and that the effect of executing pre-cooling control is small, and the execution of pre-cooling control is avoided and normal control is executed to suppress the output of the EWP4, thereby preventing a deterioration in electricity consumption.

[0066] In this embodiment, the water temperature difference ΔTw defined by "Tw1 - Tw2" is used as a parameter for determining whether or not a high outside air temperature or the like is having a cooling effect on the coolant and whether or not execution of pre-cooling control is having an effect. However, a different value may be used as this parameter. For example, a separate water temperature sensor may be used to obtain the water temperature upstream of the engine 2 (or the water temperature upstream of the EWP 4) as the third water temperature Tw3, and the value defined by "Tw1 - Tw3" may be used as the water temperature difference. A simpler configuration may be such that the first water temperature Tw1 or the third water temperature Tw3 itself is compared with a predetermined threshold value as the above parameter. Furthermore, it is also possible to detect the outside air temperature itself, the intake air temperature, the temperature inside the intake manifold (intake manifold temperature), or the like, and use this as the above parameter.

[0067] Next, a cooling control device 31 according to a third embodiment of the present invention will be described with reference to Figures 9 and 10. The configuration of the cooling control device 31 is almost the same as that of the cooling control device 1 of the above-described embodiment, but differs from the above-described embodiment in that the ECU 10 acquires map information MI via the Internet or a GPS and car navigation system installed in the vehicle and uses this information to estimate the predicted load. This will be described in detail below.

[0068] The control processing from step 901 to step 912 in FIG. 9 is similar to the control processing from step 301 to step 312 in FIG. 3, but the third embodiment is characterized in that in step 913, a terrain determination is made to determine whether or not the terrain on the vehicle's route in the near future will require high-load operation of the engine 2, and whether or not to perform pre-cooling control is determined based on the determination result (high-load terrain flag F_high-load terrain).

[0069] Figure 10 shows the subroutine for determining terrain performed in step 913 of Figure 9. In this process, first, in step 101, map information MI is acquired via the Internet or a GPS and car navigation system installed in the vehicle. The map information MI may include, for example, the current position of the vehicle acquired using the GPS and road information in the traveling direction (whether the road is straight or curved, whether there is a gradient, traffic congestion information, etc.).

[0070] Next, in step 102, it is determined whether the vehicle's required output average value PRQM is equal to or greater than the threshold output value Pref. If the result of this determination is YES, the process proceeds to step 103. In step 103, the map information MI acquired in step 101 is referenced to determine whether the road in the vehicle's traveling direction is straight. If the result of this determination is YES, it is determined that the coolant temperature is high, the vehicle's most recent operating state is high-load operation, and the road in the vehicle's traveling direction is straight, so that the predicted load of engine 2 is high. In step 104, the value of the high-load terrain flag F_high-load terrain is set to "1", and the process ends.

[0071] On the other hand, if the determination result in step 103 is NO, meaning that the road in the vehicle's traveling direction is not straight, it is determined that the predicted load on engine 2 is not large, and in step 106 the value of the high-load terrain flag F_high-load terrain is set to "0", and this process ends.

[0072] If the determination result in step 102 is NO, i.e., if the vehicle required output average value PRQM is lower than the threshold output Pref, the process proceeds to step 105. In step 105, the map information MI acquired in step 101 is referenced to determine whether the road in the vehicle's traveling direction is an uphill slope. If the determination result is YES, even if the most recent driving state is not high-load driving, it is determined that the load may become large in the near future, and the process proceeds to step 103, where it is determined whether the road in the traveling direction is straight. On the other hand, if the determination result in step 105 is NO, it is determined that the predicted load of engine 2 is not high, the process proceeds to step 106, the value of the high-load terrain flag F_high-load terrain is set to "0", and the process ends.

[0073] Returning to Fig. 9, after the above-described terrain determination is performed in step 913, the process proceeds to step 914, where it is determined whether the value of the high-load terrain flag F_high-load terrain is 1. If the result of this determination is YES, it is determined that the predicted load of engine 2 is high, and the process proceeds to step 920 via steps 918 and 919, which are the same processes as steps 317 and 318 in Fig. 3, and pre-cooling control is performed as in step 319 in Fig. 3, before terminating this process.

[0074] On the other hand, if the determination result in step 914 is NO, it is determined that the predicted load of the engine 2 is not large, and the process proceeds to step 915. In step 915, similar to step 314 in Fig. 3, it is determined whether the cooling control performed immediately before was pre-cooling control using a pre-cooling table. If the determination result in step 915 is NO, that is, the cooling control performed immediately before was not pre-cooling control, the process proceeds to step 911 via step 909 and step 910, where the drive of the EWP 4 is controlled using the base table, and this process ends.

[0075] Furthermore, if the determination result in step 915 is YES, and the cooling control performed immediately before is pre-cooling control, steps 916 and 917 perform processing similar to steps 315 and 316 in FIG. 3, and after a predetermined duration of pre-cooling control has elapsed, the process proceeds to step 911 via step 910, where the drive of EWP4 is controlled using the base table, and this process ends.

[0076] As described above, the cooling control device 31 of this embodiment estimates whether the predicted load of the engine 2 is high by taking into account not only the required output of the vehicle but also the topography in the direction of travel based on the map information MI, thereby enabling more accurate estimation of the predicted load. Furthermore, if it is determined that the predicted load is high, pre-cooling control is executed to drive the EWP 4 at a higher output than during normal control in accordance with the engine speed NE of the engine 2. This effectively cools the engine 2 by lowering the coolant temperature, thereby reducing the pressure in the combustion chamber before knocking occurs. This makes it possible to avoid situations where it is necessary to execute retard control for the engine 2, thereby improving fuel efficiency.

[0077] In this embodiment, the predicted load is estimated based on both the vehicle's required output and the map information MI. However, a simpler configuration is also possible in which the predicted load is estimated based only on the map information MI.

[0078] The present invention is not limited to the embodiments described above, but can be embodied in various forms. Furthermore, the detailed configuration can be appropriately changed within the scope of the spirit of the present invention. [Explanation of symbols]

[0079] 1 Cooling control device 2. Engine (internal combustion engine) 3 Cooling circuit 4 EWP (Electric Water Pump) 5 Radiator 6. First water temperature sensor (water temperature acquisition means) 7 Second water temperature sensor (water temperature acquisition means) 10 ECU (Predictive load estimation means, pump control means) 11 Predictive load estimation unit (predictive load estimation means) 12 Pump control unit (pump control means) 13 Rotational speed sensor (means for acquiring rotational speed) 14 Accelerator opening sensor (accelerator opening acquisition means) AP Accelerator opening MI Map Information NE rotation speed Pref Threshold output (third threshold) PRQ Request Output PRQM Required power average value Tref1 First threshold water temperature Tref2 Second threshold water temperature (first threshold) Tref3 Third threshold water temperature Tw1 1st water temperature Tw2 2nd water temperature ΔTw Water temperature difference (difference between 1st water temperature and 2nd water temperature)

Claims

1. A cooling control device for an internal combustion engine of a vehicle, the cooling control device including: a cooling circuit that cools the internal combustion engine with cooling water; and an electric water pump that is connected to the cooling circuit and circulates the cooling water through the cooling circuit, a water temperature acquisition means for acquiring the temperature of the cooling water; a rotation speed acquisition means for acquiring a rotation speed of the internal combustion engine; a predicted load estimation means for estimating a predicted load, which is a future load of the internal combustion engine; a pump control means for driving the electric water pump at an output corresponding to the acquired rotational speed when the acquired water temperature is equal to or higher than a predetermined first threshold value and the estimated predicted load is equal to or higher than a predetermined second threshold value; an accelerator opening degree acquisition means for acquiring an accelerator opening degree of the vehicle; Equipped with The predicted load estimation means calculates a required output of the vehicle based on the acquired accelerator opening and the acquired engine speed, and calculates an average value of the required output calculated within a most recent predetermined time period as the predicted load.

2. A cooling control device for an internal combustion engine of a vehicle, the cooling control device having a cooling circuit that cools the internal combustion engine with cooling water, and an electric water pump that is connected to the cooling circuit and circulates the cooling water through the cooling circuit, a water temperature acquisition means for acquiring the temperature of the cooling water; a rotation speed acquisition means for acquiring a rotation speed of the internal combustion engine; a predicted load estimation means for estimating a predicted load, which is a future load of the internal combustion engine; a pump control means for driving the electric water pump at an output corresponding to the acquired rotational speed when the acquired water temperature is equal to or higher than a predetermined first threshold value and the estimated predicted load is equal to or higher than a predetermined second threshold value; Equipped with a pump control means for controlling the electric water pump so that the electric water pump is driven for a predetermined period of time when the predicted load falls below the second threshold value after the electric water pump is driven;

3. further comprising an outside air temperature parameter acquisition means for acquiring an outside air temperature parameter representing an outside air temperature; 2. The cooling control device for an internal combustion engine according to claim 1, wherein the pump control means reduces the output of the electric water pump when the acquired outside air temperature parameter is equal to or higher than a predetermined fourth threshold value.

4. A cooling control device for an internal combustion engine of a vehicle, the cooling control device having a cooling circuit that cools the internal combustion engine with cooling water, and an electric water pump that is connected to the cooling circuit and circulates the cooling water through the cooling circuit, a water temperature acquisition means for acquiring the temperature of the cooling water; a rotation speed acquisition means for acquiring a rotation speed of the internal combustion engine; a predicted load estimation means for estimating a predicted load, which is a future load of the internal combustion engine; a pump control means for driving the electric water pump at an output corresponding to the acquired rotational speed when the acquired water temperature is equal to or higher than a predetermined first threshold value and the estimated predicted load is equal to or higher than a predetermined second threshold value; Equipped with A radiator for cooling the cooling water is connected to the cooling circuit, the water temperature acquisition means acquires a water temperature of the cooling circuit downstream of the internal combustion engine as a first water temperature and a water temperature of the cooling circuit downstream of the radiator as a second water temperature, The pump control means reduces the output of the electric water pump when the difference between the first water temperature and the second water temperature falls below a predetermined fifth threshold.

5. further comprising a map information acquisition means for acquiring map information; 2. The cooling control device for an internal combustion engine according to claim 1, wherein the predicted load estimating means estimates the predicted load based on the acquired map information.

Images