JP2005256642A - Cooling control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling control device for an internal combustion engine controlling a motor to compensate predetermined cooling capacity to the internal combustion engine even if the capacity of the motor fluctuates due to the variation of environmental temperature or the like. <P>SOLUTION: The engine 2 is provided with a cooling device for cooling the engine 2 by circulating cooling water between a radiator 5 and the engine 2 by an electric water pump 6 driven by a pump driving motor. An ECU 26 computes basic output Pb(%) which is a duty ratio to be outputted to the pump driving motor, assuming capacity at a control reference temperature Tf from a map stored in a ROM 29 according to a water temperature thw, then estimates a motor temperature Tm, computes the temperature difference Ts from the control reference temperature Tf, determines an output correction factor V from the map, based on the temperature difference Ts, and corrects the basis output Pb(%). Consequently, even if the capacity of the pump driving motor fluctuates due to the variation of temperature, the electric water pump 6 can be driven with discharge corresponding to the requested cooling capacity. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cooling control device for an internal combustion engine, and more specifically, a cooling control device for an internal combustion engine provided with a cooling device that cools the internal combustion engine by circulating cooling water between radiators by an electric water pump driven by a motor. About.

  For example, in a cooling device that cools an internal combustion engine through heat exchange by circulating a water jacket and a radiator of an internal combustion engine such as a gasoline engine for automobiles through heat exchange, the water is circulated by a water pump. I was allowed to. Then, according to the temperature of the cooling water, the liquid temperature is adjusted by controlling so as to increase the flow rate to the bypass circuit in the cold state by a thermostat driven by a thermo wax or the like. As a conventional water pump, for example, there is one which is connected to a crankshaft of an internal combustion engine and is directly driven by the internal combustion engine. In the water pump having such a configuration, the higher the engine speed, the higher the cooling water flow rate and the higher the cooling capacity. The lower the engine speed, the lower the cooling water flow rate and the lower the cooling capacity. . However, even in low-load operation where cooling is not so necessary, the water pump is driven according to the rotation of the engine, so the fuel energy is excessively absorbed in the cooling water and discharged to the outside as waste energy. There was a problem that the consumption rate deteriorated. On the other hand, in the case of high load operation even at low rotation, there is a problem that the cooling capacity is insufficient because the water pump does not rotate more than a certain speed.

Therefore, like the engine cooling device shown in Patent Document 1, the number of rotations of a motor that drives an electric water pump is controlled by a control circuit having a microcomputer in accordance with a change in the temperature of cooling water. was suggested. In such an engine cooling device, since the computer control is performed according to the temperature change of the cooling water, when the temperature of the cooling water is high, the motor current is greatly output to increase the rotation speed of the water pump. On the other hand, when the temperature of the cooling water is low, the motor current is reduced and the number of rotations of the water pump is lowered. As a result, it was supposed that the engine cooling could be controlled optimally.
Japanese Patent Application Laid-Open No. 60-142010

  However, during operation of the electric water pump that circulates the cooling water, the motor characteristics may change due to environmental temperature changes. In the engine cooling device disclosed in Patent Document 1, control according to the temperature change of the cooling water is performed, but the temperature of the motor itself is not taken into consideration. For this reason, the gain of the motor as the actuator fluctuates. For example, when the motor becomes higher than the temperature assumed in advance, the discharge amount of the electric water pump decreases even if the current according to the control is output. Will do. As a result, there was a problem that the cooling performance required in the cooling device could not be obtained and overheating or the like was likely to occur.

  On the other hand, when the temperature of the motor drops, the discharge amount becomes excessive even if a current according to the control is output, and it is cooled more than necessary to prevent the temperature from rising to the appropriate temperature, or the fuel consumption deteriorates, There is also a problem that wasteful current for driving is consumed.

  The present invention provides a cooling control apparatus for an internal combustion engine that controls a motor so as to compensate a predetermined cooling capacity for the internal combustion engine even if the environmental temperature or the like changes and the motor performance fluctuates. is there.

  In order to solve the above-described problem, in the cooling control apparatus for an internal combustion engine according to claim 1, an internal combustion engine provided with a cooling apparatus for cooling the internal combustion engine by circulating cooling water between the radiators by an electric water pump driven by a motor. An internal combustion engine cooling control device comprising motor control means for determining an output of a drive current to the motor in accordance with a state of the internal combustion engine, and determining a temperature of the motor And an output correcting means for correcting the output to the motor determined by the motor control means in accordance with the motor temperature determined by the motor temperature determining means.

  According to the present invention, the output correction means corrects the output of the motor control means to the motor in accordance with the motor temperature determined by the motor temperature determination means. Even so, there is an effect that the motor can be controlled so as to compensate the predetermined cooling capacity for the internal combustion engine.

  According to a second aspect of the present invention, there is provided the internal combustion engine cooling control apparatus according to the first aspect, wherein the motor control means is based on the performance of the motor exerted at a set control reference temperature. The output to the motor is determined, and the output correction means corrects the output of the motor control means to the motor based on the difference between the motor temperature determined by the motor temperature determination means and the control reference temperature. The gist.

  According to this invention, the output correction means corrects the output of the motor control means to the motor based on the difference between the motor temperature determined by the motor temperature determination means and the control reference temperature. There is an effect that can be performed.

  According to a third aspect of the present invention, there is provided the internal combustion engine cooling control apparatus according to the second aspect, wherein the output correction means preliminarily outputs an output correction value corresponding to a temperature difference with respect to a control reference temperature of the motor. The gist is to perform correction using a mapped temperature correction map.

  According to the present invention, the output correction means corrects the output correction value corresponding to the temperature difference with respect to the control reference temperature of the motor by the temperature correction map previously mapped. Even if the correction values are nonlinear, there is an effect that optimal motor control can be performed.

  The internal combustion engine cooling control apparatus according to any one of claims 1 to 3, wherein the motor temperature determination means includes an outside air temperature, an intake air temperature, a vehicle speed. The environmental change factor of the motor including one or more of these values, and the self-heating factor of the motor including one or more of the voltage applied to the motor, the output current, the coolant temperature, or the history thereof. Based on this, the gist is to estimate the motor temperature.

  According to this invention, since the motor temperature determination means estimates the motor temperature based on the environmental change factor and the self-heating factor of the motor, it is possible to control the motor with higher accuracy based on accurate temperature estimation. There is.

  The internal combustion engine cooling control apparatus according to any one of claims 1 to 3, wherein the motor temperature determination means directly controls the temperature of the motor. The gist is to detect with a detector.

  According to this invention, since the motor temperature determination means detects the temperature of the motor directly with the temperature detector, the motor temperature can be detected without estimation and the motor can be controlled at an accurate temperature. There is.

  The internal combustion engine cooling control apparatus according to any one of claims 1 to 5, wherein the state of the internal combustion engine is a coolant temperature. Is the gist.

  According to the present invention, since the motor control means controls the motor with the coolant temperature as the state of the internal combustion engine, the motor can be controlled so that the coolant temperature is appropriate.

  The internal combustion engine cooling control apparatus according to any one of claims 1 to 6, wherein the motor control means changes a duty ratio by PWM control. The gist is to control the motor.

  According to the present invention, the motor control means outputs the current to the motor by changing the duty ratio by the PWM control, so that the motor can be controlled with high accuracy.

  According to the cooling control apparatus for an internal combustion engine of the present invention, even when the environmental temperature or the like changes and the motor capacity fluctuates, the motor can be controlled to compensate the predetermined cooling capacity for the internal combustion engine. There is an effect that can be done.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying a cooling control apparatus for an internal combustion engine according to the present invention will be described below with reference to FIGS.
FIG. 1 is a schematic configuration diagram schematically showing an internal combustion engine cooling device and its peripheral configuration according to the present embodiment, together with an engine 2 that is an internal combustion engine mounted on a vehicle 1.

  An engine 2 mounted as an internal combustion engine in the vehicle 1 is, for example, a four-cycle gasoline engine including a cylinder block 3b that forms a multi-cylinder cylinder and a cylinder head 3a that is disposed on the cylinder block 3b. In the combustion chambers of the plurality of cylinders formed inside the cylinder head 3a and the cylinder block 3b, the fuel / air mixture supplied therein is combusted. When the piston is reciprocated based on the combustion of the air-fuel mixture, the crankshaft 4 that is the output shaft rotates. Along with the combustion of the air-fuel mixture, high heat is generated in the cylinder head 3a and the cylinder block 3b. The heat generated in the engine 2 is proportional to the amount of gasoline to be burned, that is, approximately the engine output. Therefore, in the case of high load operation or the like, a larger amount of heat is generated from the cylinder head 3a and the cylinder block 3b of the engine 2.

  On the other hand, a water-cooling type cooling device provided for cooling the cylinder head 3a, the cylinder block 3b, and the like includes a radiator 5, which is a heat exchanger, an electric water pump 6, a thermostat 7, a cooling pipe 8, and the like. . Further, a cylinder block water jacket 9b, which is a heat exchanger provided with a passage of cooling water that is a cooling heat medium disposed so as to wrap the cylinder, is formed inside the cylinder block 3b. Further, a cylinder head water jacket 9a is formed in the cylinder head 3a. The electric water pump 6 causes cooling water to flow into the relatively low temperature cylinder block water jacket 9b, cools the cylinder block 3b, and then flows into the cylinder head water jacket 9a to cool the higher temperature cylinder head 3a. Then, after passing through an outlet housing (not shown) provided in the vicinity of the rear end of the cylinder head 3 a, the cooling water flows from the water jacket outlet 10 to the radiator 5 through the first cooling water passage 11. The temperature of the cooling water passing through this outlet housing (not shown) is the highest in the cooling water channel. Therefore, a water temperature sensor 31 is provided in the outlet housing (not shown).

  Here, the first cooling water passage 11 connected to the water jacket outlet 10 is connected to the radiator inlet 12. The second cooling water passage 14 connected to the radiator outlet 13 is connected to the water jacket inlet 15 via the thermostat 7 and the electric water pump 6. A bypass passage 16 connected in the middle of the first cooling water passage 11 bypasses the radiator 5 and is connected to the thermostat 7.

  The thermostat 7 is a three-way valve, and includes an output port that communicates with the suction side of the electric water pump 6, a first input port that communicates with the radiator outlet 13, and a second input port to which the bypass passage 16 is connected. The thermostat 7 communicates the second input port with the output port when the coolant temperature thw is lower than a predetermined value. As a result, the cooling water flowing out from the cylinder head water jacket 9a to the first cooling water passage 11 bypasses the radiator 5, returns to the electric water pump 6, and is sent again to the cylinder block water jacket 9b. The cooling water is gradually warmed through this cooling water circulation, and the cylinder head 3a and the cylinder block 3b are warmed up by the warm cooling water.

  On the other hand, when the coolant temperature thw is higher than a predetermined value, the first input port and the output port of the thermostat 7 communicate with each other. Thereby, the cooling water flowing through the first cooling water passage 11 flows to the radiator 5, and the cooling water passes through the second cooling water passage 14, the thermostat 7 and the electric water pump 6 from the cylinder block water jacket 9 b to the cylinder head water. Liquid is fed to the jacket 9a. Through the circulation of the cooling water, the heat of the cylinder block 3b and the cylinder head 3a is taken away by the cooling water, and the cylinder block 3b and the cylinder head 3a are cooled. On the other hand, in the radiator 5, the heat of the cooling water is radiated to the outside, and the cooling water is cooled and returned to the cylinder block water jacket 9b. Therefore, when the water temperature thw is high, the rotation of the electric water pump 6 is accelerated to increase the circulation of the cooling water, so that the heat from the cylinder head 3a and the cylinder block 3b is transferred to the cylinder head water jacket 9a and the cylinder block water jacket 9b. Can be absorbed more, and the radiator 5 can dissipate more heat.

  The radiator 5 is installed behind the front grille 17 of the vehicle 1. The radiator 5 includes a radiator tank that primarily stores cooling water and a radiator core that communicates with the radiator tank. The radiator core is provided with a number of flat tubes provided with fins, which are heat sinks made of elongated aluminum plates, and circulates the stored cooling water. Accordingly, when the vehicle 1 is traveling, the traveling wind that has passed through the front grille 17 hits the radiator 5, and the cooling water passing through the radiator 5 is cooled.

  The cooling electric fan 18 provided in the radiator 5 supplies the cooling air necessary for heat exchange in the radiator 5 to the radiator 5. When sufficient cooling air is supplied to the radiator 5 during traveling, the cooling water is sufficiently cooled even if the electric fan 18 is stopped. When the running wind does not hit the radiator 5 or when the air volume is small, such as during idle operation, the radiator 5 can be forcibly cooled by operating the electric fan 18.

  The cooling device of the present embodiment is configured as described above. Normally, the electric water pump 6 and the electric fan 18 are controlled by the ECU 26 according to the water temperature thw, so that the cooling water can be sufficiently cooled. However, if the control by the ECU 26 cannot be controlled appropriately as the target, the amount of heat generated cannot be cooled, and as a result, the temperature in the cylinder head 3a and the cylinder block 3b rises. In particular, when the temperature of the cooling water exceeds the boiling point, the cooling capacity is further significantly reduced and the engine 2 is overheated. In this case, the temperature in the cylinder becomes extremely high. In an extreme case, seizure may occur and the engine 2 may be damaged.

  Next, the power supply device 22 will be described. The power supply device 22 includes a battery 20, an alternator 21, and the like. The alternator 21 is drivingly connected to the crankshaft 4, and the electric power generated by the alternator 21 is supplied to the battery 20, the pump drive motor 25, and the fan motor 19. The pump drive motor 25, the fan motor 19, and the battery 20 are electrically connected in parallel to the alternator 21. Then, a drive current is supplied from the power supply device 22 to the pump drive motor 25 of the electric water pump 6 via the pump drive motor drive circuit 24. Similarly, electric power is supplied to the fan motor 19 of the electric fan 18 via the fan motor drive circuit 23.

  That is, in the electric water pump 6, when the pump drive motor drive circuit 24 is turned on by a control signal output from the ECU 26, the drive current from the battery 20 is supplied to the pump drive motor 25 via the pump drive motor drive circuit 24. It is supplied and driven. In the electric water pump 6, the current output to the pump drive motor 25 is changed by the pump drive motor drive circuit 24 in accordance with the control signal output from the ECU 26, and the discharge amount of the electric water pump 6 is changed.

  Specifically, in the electric water pump 6 of the present embodiment, the pump drive motor 25 is controlled by the ECU 26, and the pump drive motor drive circuit 24 controls the pump water at a stepless rotation speed according to the water temperature thw. Of course, it goes without saying that what control is performed based on any numerical value such as the water temperature thw and the water pressure of the cooling water can be appropriately changed.

  Similarly, the fan motor drive circuit 23 outputs a drive signal to the fan motor 19 based on a control signal output from the ECU 26 when the coolant temperature thw becomes a predetermined value (eg, 93 ° C.) or higher. . When the electric fan 18 is driven, the fan motor 19 is variable, for example, switched to two stages by the fan motor driving circuit 23, so that the electric fan 18 is driven at three stages of rotation speeds: stop, low speed, and high speed.

  Next, various sensors will be described. An outlet housing (not shown) is provided in the vicinity of the rear end portion of the cylinder head 3a, and a water temperature sensor 31 for detecting the water temperature thw of the cooling water flowing therethrough is provided. The ECU 26 calculates the water temperature thw based on the detection signal from the water temperature sensor 31 and controls the electric fan 18 and the electric water pump 6. Of course, it does not preclude referring to numerical values other than the water temperature thw.

  FIG. 2 is a block diagram schematically showing the flow of cooling water and the flow of control signals in the present embodiment. In addition to the water temperature sensor 31, the engine 2 is provided with various sensors for detecting the engine operating state. For example, a throttle opening sensor 38 is provided in the vicinity of the throttle valve 36 that regulates the amount of air in the intake passage taken into the cylinder of the engine 2, and detects the throttle opening that is the opening of the throttle valve 36. . An intake air amount is detected by an air flow meter 39 provided on the upstream side of the throttle valve 36. In addition, the intake air temperature detected by the intake thermometer 40 sucked into the intake passage, the knock signal detected by the knock sensor 41 provided in the vicinity of the cylinder, the vehicle speed detected by the vehicle speed meter, and the like are detected. . A rotation speed sensor 43 provided close to the crankshaft 4 outputs a pulse signal having a frequency corresponding to the rotation speed of the engine 2 based on the rotation of the crankshaft 4. Based on this output signal (pulse signal), the rotational speed (engine rotational speed) NE of the engine 2 (crankshaft 4) is detected. The outside air temperature sensor 44 measures the outside air temperature and detects the outside air temperature.

  The ECU 26, which is a control device, comprehensively performs ignition timing control, fuel injection control, which is control of the engine 2 itself, and drive control of the electric water pump 6, electric fan 18, which is a cooling device, as a cooling control device. Control. The ECU 26 is configured around a known computer having a central processing unit (CPU 27). The ECU 26 is bus-connected to a ROM 29 that stores various programs such as a cooling control program for the internal combustion engine of the present embodiment, a map, and the like, and a RAM 28 that temporarily stores values taken from the sensors, CPU calculation results, and the like. Is provided. In addition, the ECU 26 is provided with a backup RAM and an input / output interface 30 for storing calculation results and prestored data after the engine is stopped.

  Detection signals from the water temperature sensor 31, the accelerator pedal 37, the throttle opening sensor 38, the air flow meter 39, the intake air temperature meter 40, the knock sensor 41, the vehicle speed meter 42, the rotation speed sensor 43, the outside air temperature sensor 44, and the like are input / output interface 30. Is input. The operation state and cooling state of the engine 2 are detected by these sensors and the like.

  The input / output interface 30 outputs control signals to the fan motor drive circuit 23 of the electric fan 18 and the pump drive motor drive circuit 24 of the electric water pump 6. The control circuit is also connected to a drive circuit (not shown) for driving a fuel injection valve of the engine 2 and an ignition coil drive circuit (not shown) for applying a high voltage to a spark plug provided in the cylinder. . Based on the signals from these sensors and the like, the ECU 26 follows the control program and initial data stored in the ROM 29, and the electric fan 18, the electric water pump 6, the fuel injection valve (not shown), and the ignition coil (not shown). Control).

  Next, the pump drive motor 25 that drives the electric water pump 6 will be described in detail. The pump drive motor 25 is a direct current motor controlled by PWM (Pulse Width Modulation), and the duty ratio (%), which is the ratio of on time to off time, is changed by changing the pulse width of a predetermined voltage applied to the motor. As a result, the time for outputting the drive current is changed. As a result, the rotational speed is controlled by changing the supplied electric power. The ECU 26 calculates a duty ratio (%) for rotating according to the required cooling capacity based on the water temperature thw and the like, and the pump drive motor drive circuit 24 drives the pump based on this duty ratio (%). The motor 25 is caused to send a drive signal of a pulse having a predetermined energization width. The pump drive motor 25 controlled in this way rotates the electric water pump 6 at a predetermined rotational speed to generate a required discharge amount (circulation amount) and controls the cooling capacity of the cooling device. The required cooling capacity is determined by a map (see FIG. 3) stored in the ROM 29 of the ECU 26 based on the difference between the current water temperature thw and the target water temperature thw, and the pump drive motor 25 is controlled with an output corresponding thereto. Drive while.

  By the way, the characteristics of the pump drive motor 25 change depending on the ambient temperature. Specifically, the torque varies due to a temperature change in the magnetic flux density of the magnet and a temperature change in the armature winding. The generated torque of the motor is [F (N) where F (N) is the kinetic energy, B (T) is the magnetic flux density, I (A) is the current value flowing through the wire, and L (m) is the effective wire length. N) = B (T) · I (A) · L (m)]. Here, the residual magnetic density Br (B) of the permanent magnet decreases with increasing temperature. For example, a ferrite magnet has been found to decrease by -0.18% per 1 ° C. For this reason, if the temperature difference is 100 ° C., [−0.18 (% / ° C.) × 100 (° C.) = − 18%]. In addition to this, when the temperature of the armature winding also rises by 1 ° C, the internal resistance increases by about + 0.4%. Although there are differences depending on the configuration of the motor, such as the type of permanent magnet and the length of the armature winding, the torque of the pump drive motor 25 decreases due to the temperature rise, the rotation speed of the electric water pump 6 decreases, and cooling It is clear that the cooling capacity is reduced by reducing the water discharge amount and the cooling water circulation amount. For example, in the case of using a ferrite magnet, if there is a difference of 100 ° C., there is a torque drop of about 20%.

  The temperature of the pump drive motor 25 varies due to the influence of the following factors. First, there is one derived from self-heating of the pump drive motor 25 itself. For example, the heat generation changes according to the load of the pump drive motor 25 such as the voltage / current applied to the pump drive motor 25, the duty ratio of the drive signal, and the history of the water temperature thw so far. Thus, among the factors affecting the temperature of the pump drive motor 25, there are those derived from self-heating. In the present application, these factors derived from self-heating are referred to as “self-heating factors”.

  On the other hand, in an environment where the outside air temperature is high, the temperature of the pump drive motor 25 is directly increased by the outside air temperature, or the heat dissipation efficiency of the pump drive motor 25 itself is lowered and the temperature easily rises. In addition, the vehicle speed of the vehicle 1 increases the amount of air passing to the radiator 5 and increases the cooling capacity. Thus, among the factors that affect the temperature of the pump drive motor 25, there are those derived from environmental changes. The parameters indicating the state of the environment include the outside air temperature, the intake air temperature, the vehicle speed, and the like. In the present application, these factors are referred to as “environment change factors” as factors associated with environmental changes.

  Thus, the temperature of the pump drive motor 25 itself is determined by the influence of these self-heating factors and environmental change factors. Conversely, if you know in advance these self-heating factors and environmental change factors, and the sensitivity coefficients for temperature changes caused by them, you can analyze and calculate these self-heating factors and environmental change factors. Thus, the motor temperature Tm (° C.) of the pump drive motor 25 can be accurately estimated.

  Since each of the self-heating factor and the environmental change factor has a different degree of influence on the temperature rise of the pump drive motor 25, the effect of each factor on the motor temperature rise is used as a sensitivity coefficient, and data is obtained through actual vehicle experiments and simulation experiments. Collect and ask. If these self-heating factors and environmental change factors and their respective sensitivity coefficients are known, the ECU 26 calculates the motor temperature Tm (° C) of the pump drive motor 25 based on the self-heating factors and the environmental change factors. Is possible.

  As described above, the motor temperature Tm (° C) can also be estimated by calculation, but calculating the influence of each of the self-heating factor and the environmental change factor each time is a load on the ECU 26. Will be applied. In addition, since these factors and their influence on temperature rise are not necessarily linearly related, in this embodiment, the data obtained by simulation experiments for these relationships are mapped and stored in the ROM 29 in advance. The temperature is estimated based on the self-heating factor and the environmental change factor. This map is high-dimensional data in which the motor temperature Tm (° C.) specified by each factor is stored as table data of one temperature for a plurality of factors. Note that this map stores temperature changes for each factor as one-to-one table data and estimates the motor temperature Tm (° C) by calculating from these temperature changes and further maps Needless to say, the motor temperature Tm (° C.) may be estimated by a combination of the above and mathematical expressions. This map, mathematical formulas for calculation, and sensitivity coefficient are stored in the ROM 29.

  From the above-described configuration, the ECU 26 serves as a motor temperature determination means, such as an outside air temperature, an intake air temperature, a vehicle speed environment change factor, a voltage applied to the pump drive motor 25, a current, a duty ratio of a drive signal, and a coolant temperature. Alternatively, the temperature of the pump drive motor 25 is estimated based on the self-heating factor of these histories. Of course, the self-heating factor and the environmental change factor are not limited to those exemplified, and there are various factors, and it goes without saying that the use of these factors is not hindered. In the present embodiment, for example, the motor temperature Tm (° C) is estimated with reference to the history of voltage / current, duty ratio, and water temperature as self-heating factors, and the outside air temperature, intake air temperature, and vehicle speed as environmental change factors. To do.

  Further, the ECU 26 functions as a motor control means, and as a basic control, the water temperature thw is based on the performance of the motor exhibited at the set “control reference temperature Tf (° C.) (motor performance precondition temperature)”. Accordingly, the output to the pump drive motor 25 is determined. The “control reference temperature Tf (° C.)” is a predetermined temperature of the pump drive motor 25 specified in advance, and the output characteristic indicating the performance of the pump drive motor 25 at that temperature is the basic characteristic here. It is regarded as a standard of control. Based on the output characteristics of the control reference temperature Tf (° C), the amount of power supplied to the pump drive motor 25 corresponding to the discharge amount required by the ECU 26 is calculated as the basic output Pb (%), and the pump drive motor drive A value serving as the basis of the control signal to be sent to the circuit 24 is calculated.

  FIG. 3 is a diagram conceptually showing a map showing the relationship between the water temperature thw and the basic output Pb (%). The ROM 29 stores a water temperature thw and a duty ratio value of PWM control output to the pump drive motor 25 for the water temperature thw as a basic output Pb (%) as a map. Here, as shown in FIG. 3, until the water temperature thw (° C.) reaches the minimum temperature Ta (° C.), the basic output Pb (%) is set to the minimum output Pm (%), and the electric water pump 6 has the minimum value. The discharge amount. That is, even when the water temperature thw is low, the electric water pump 6 is controlled so as not to be stopped. When the water temperature thw is higher than the minimum temperature Ta (° C), the output increases accordingly. For example, when the water temperature thw (° C) is Tb (° C), the basic output Pb (%) is Pp (%)become. In addition, as for this relationship, data obtained from experiments or simulation experiments using actual vehicles is stored as a map. Specifically, a one-to-one relationship between the water temperature thw and the basic output Pb (%) is stored as table data in the ROM 29. Is remembered. Note that the relationship of the basic output Pb (%) with respect to the water temperature thw (° C.) may be stored as a function, not limited to the map.

  As mentioned above, it is necessary to modify this basic control because its characteristics change as the motor temperature changes. Therefore, the ECU 26 functions as an output correction unit and performs correction control for the basic control as described above. In this correction control, the temperature difference Ts (° C) is obtained from the difference between the motor temperature Tm (° C) determined by the ECU 26 serving as the motor temperature determination means and the control reference temperature Tf (° C). Based on the difference Ts (° C), the output to the pump drive motor 25 determined by the ECU 26 as the motor control means is corrected.

  Here, FIG. 4 is a diagram conceptually showing a map showing the relationship between the temperature difference Ts (° C.) of the pump drive motor 25 and the output correction coefficient V. In this map, the horizontal axis indicates the temperature difference Ts (° C), and the vertical axis indicates the output correction coefficient V that is an output correction value for correcting the duty ratio. This output correction coefficient V is a correction value to be added (subtracted) to the basic output Pb (%), which is the duty ratio, and is multiplied by the basic output Pb (%) with the basic output Pb (%) as a reference. A correction value for increasing or decreasing the basic output Pb (%) is calculated. The output correction coefficient V increases the basic output Pb (%) when the value is positive, and decreases the basic output Pb (%) when the value is negative. There is a relatively strong correlation between the temperature difference Ts (° C) and the output correction coefficient V. If the temperature difference Ts (° C) becomes positive, the output correction coefficient V increases and the temperature difference Ts (° C) ) Becomes negative, the output correction coefficient V also becomes a negative value and becomes small, but it does not become a complete linear relationship but changes under various conditions. Therefore, in this embodiment, the relationship between the temperature difference Ts (° C.) and the output correction coefficient V is obtained by experiments or simulation experiments using an actual vehicle, mapped, and this map is referred to correspond to the temperature difference Ts (° C.). The value of the output correction coefficient V to be obtained is obtained. The diagram shown in FIG. 4 is a diagram conceptually showing a map for explanation. In practice, the map is a one-to-one table of temperature difference Ts (° C.) and output correction coefficient V based on digital data. It is stored in the ROM 29 as data.

  A control method by the cooling control device for the engine 2 configured as described above will be described with reference to FIG. Here, FIG. 5 is a flowchart showing the procedure of the control method by the cooling control device for the engine 2 of the present embodiment. First, when the engine is started and the ECU 26 is started, control is started (START). First, the ECU 26 receives a detection signal from the water temperature sensor 31 at a predetermined timing from the input / output interface 30, calculates the coolant water temperature thw, and reads it into the RAM 28 (step 1 (hereinafter “step” is referred to as “S”). Abbreviated))). Next, the CPU 27 reads the basic output Pb (%) corresponding to the water temperature thw read into the RAM 28 from the map (see FIG. 3) stored in the ROM 29, and determines the basic output Pb (%) (S2). This basic output Pb (%) is a tentative output before correction. Actually, the basic output Pb (%) is not output as it is and does not send a control signal to the pump drive motor drive circuit 24.

  Subsequently, the motor temperature Tm (° C.) is estimated (S3). In this step, as described above, the ROM 29 is based on the voltage / current, duty ratio, water temperature history detected by the ECU 26 from various sensors, the ambient temperature, the intake air temperature, and the vehicle speed, which are environmental change factors. The motor temperature Tm is estimated from the map stored in. Subsequently, the CPU 27 obtains a temperature difference Ts (° C.) between the control reference temperature (motor performance prerequisite temperature) Tf (° C.) stored in the ROM 29 and the motor temperature Tm (° C.) estimated in S3. [Ts (° C) = Tm (° C) −Tf (° C)] is calculated (S4).

  Next, the CPU 27 determines an output correction coefficient V corresponding to the performance change corresponding to the obtained temperature difference Ts (° C.) based on a map (see FIG. 4) stored in the ROM 29 (S5). Based on the determined output correction coefficient V, a correction value to be added to or subtracted from the basic output Pb (%) determined in S2 is calculated to finally determine a duty ratio to be output, and a corresponding control signal is calculated. To the pump drive motor drive circuit 24 (S6). If it does so, the pump drive motor drive circuit 24 will output a drive signal to the pump drive motor 25 with the duty ratio instruct | indicated by the control signal. The pump drive motor 25 driven by this output rotates the electric water pump 6 with the required discharge amount to circulate the cooling water, and gives the required cooling capacity to the cooling device. When the process is completed, the procedure from S1 is executed again at a predetermined timing (RETURN → S1).

  In the present embodiment, the ECU 26 that executes the procedure of S3 corresponds to an example of a motor temperature determination unit, and the ECU 26 that executes the procedures of S4 to S6 corresponds to an example of an output correction unit.

According to the cooling control device for the engine 2 of the embodiment, the following effects can be obtained.
(1) In the above embodiment, the temperature difference Ts (° C) is obtained from the control reference temperature Tf (° C) and the motor temperature Tm (° C) according to the estimated motor temperature Tm (° C). The basic output Pb (%) is corrected. Therefore, even if the environmental temperature or the like changes and the capacity of the pump drive motor 25 fluctuates, the electric water pump 6 is driven to control the cooling device so as to compensate the predetermined cooling capacity for the engine 2. There is an effect that can be.

(2) Particularly, since the basic output Pb (%) is corrected with reference to the map (see FIG. 4), there is an effect that more appropriate correction can be performed.
(3) The estimated motor temperature Tm (° C) is determined by referring to voltage / current, duty ratio, and water temperature history as self-heating factors, and outside air temperature, intake air temperature, and vehicle speed as environmental change factors. Since the motor temperature Tm (° C.) is estimated, the temperature of the pump drive motor 25 can be estimated by software regardless of actual measurement. This eliminates the need for hardware for actual measurement with only the ECU 26, and does not increase the number of parts and increase the number of manufacturing steps.

(4) Further, since this estimation is performed using a map based on a plurality of factors, it is possible to perform estimation with high accuracy.
(5) Since the basic output Pb (%) is determined based on the water temperature thw, there is also an effect that the water temperature thw can be appropriately controlled. In particular, since the basic output Pb (%) is determined based on the water temperature thw based on the map (see FIG. 3), a more appropriate basic output Pb (%) can be obtained.

  And since the control with respect to the pump drive motor 25 is controlled by changing the duty ratio by PWM control, there exists an effect that a highly precise motor control can be performed.

In addition, you may change the said embodiment as follows.
The flowchart shown in FIG. 5 is an embodiment of the present invention, and it goes without saying that other processes can be added, deleted, or the order can be changed.

  In the present embodiment, the basic output Pb (%) is determined only by the water temperature thw, but may be determined by an element other than the water temperature thw. For example, control corresponding to an increase in the load of the engine 2 may be performed from the throttle opening detected by the throttle opening sensor 38, the intake air amount detected from the air flow meter 39, and the like. Based on the knock signal from the knock sensor 41, the temperature rise in the cylinder may be detected to correct the required cooling capacity. Alternatively, the required cooling capacity may be corrected in conjunction with a switch of an air conditioner (not shown).

  In addition, although the rotation control of the pump drive motor 25 is controlled by PWM control, it is needless to say that the present invention is not limited to this. For example, any method that can control the rotational speed, such as PAM control, vector control, pulse control, bipolar control, pedestal control, and voltage control by resistance control, can be selected as appropriate.

  In the present embodiment, the relationship between the water temperature thw and the basic output Pb (%), the estimation of the motor temperature Tm (° C), the relationship between the temperature difference Ts (° C) of the pump drive motor 25 and the output correction coefficient V. Is obtained using a map, but it may be obtained using a function formula or the like without depending on the map.

  In the present embodiment, the motor temperature Tm (° C) is obtained by estimation, but the motor temperature Tm (° C) may be an actual value measured by a temperature detector. It goes without saying that various modifications and improvements can be made by those skilled in the art without departing from the scope of the claims.

The schematic block diagram which shows typically the cooling device of the internal combustion engine concerning this Embodiment, and those peripheral structures with the engine 2 which is the internal combustion engine mounted in the vehicle 1. FIG. The block diagram which shows typically the flow of the cooling water of this embodiment, and the flow of a control signal. The figure which shows notionally the map which shows the relationship between water temperature thw and basic output Pb (%). The figure which shows notionally the map which shows the relationship between the temperature difference Ts (degreeC) of the pump drive motor 25, and the output correction coefficient V. The flowchart which shows the procedure of the control method by the cooling control apparatus of the engine 2 of this embodiment.

Explanation of symbols

  2 ... Engine (internal combustion engine), 5 ... Radiator (cooling device), 6 ... Electric water pump (cooling device), 7 ... Thermostat (cooling device), 8 ... Cooling pipe (cooling device), 9a ... Cylinder head water jacket ( Cooling device), 9b ... Cylinder block water jacket (cooling device), 18 ... Electric fan (cooling device), 24 ... Pump drive motor drive circuit, 25 ... Pump drive motor (motor), 26 ... ECU (cooling control device, motor) Control means, motor temperature determination means, output correction means), 31 ... water temperature sensor, Tf ... control reference temperature, Tm ... motor temperature, Ts ... temperature difference, thw ... water temperature

Claims (7)

With respect to an internal combustion engine provided with a cooling device for cooling the internal combustion engine by circulating cooling water between the radiators by an electric water pump driven by a motor, the drive current to the motor is controlled according to the state of the internal combustion engine. A cooling control device for an internal combustion engine comprising motor control means for determining an output,
Motor temperature determining means for determining the temperature of the motor;
An internal combustion engine cooling control device comprising: an output correction unit that corrects an output to the motor determined by the motor control unit according to a motor temperature determined by the motor temperature determination unit. The motor control means determines the output to the motor based on the performance of the motor exhibited at a set control reference temperature;
The output correction unit corrects an output of the motor control unit to the motor based on a difference between the motor temperature determined by the motor temperature determination unit and the control reference temperature. The internal combustion engine cooling control apparatus. 3. The cooling control apparatus for an internal combustion engine according to claim 2, wherein the output correction means corrects an output correction value corresponding to a temperature difference with respect to a control reference temperature of the motor by a temperature correction map that is previously mapped. The motor temperature determining means includes an environmental change factor of the motor including a numerical value of one or more of outside air temperature, intake air temperature, and vehicle speed,
Further, the motor temperature is estimated based on a self-heating factor of the motor including a voltage applied to the motor, an output current, a coolant temperature, or one or more values of these histories. The cooling control apparatus for an internal combustion engine according to any one of claims 1 to 3. The internal combustion engine cooling control apparatus according to any one of claims 1 to 3, wherein the motor temperature determination unit directly detects the temperature of the motor by a temperature detector. The cooling control device for an internal combustion engine according to any one of claims 1 to 5, wherein the state of the internal combustion engine is a coolant temperature. The internal combustion engine cooling control apparatus according to any one of claims 1 to 6, wherein the motor control means controls the motor by changing a duty ratio by PWM control.

Images