JPH1122465A - Cooling control device for internal combustion engine and cooling control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control temperature in high precision in a state of predicting temperature transition of a cooling water in an internal combustion engine. SOLUTION: A butterfly valve 34b to regulate a flow rate of a cooling water is rotationally controlled through a direct current motor 31, a clutch mechanism 32 and a reduction gear mechanism 33 and cools an engine at optimum temperature. A PWM signal generated by quick-response control and PI control at least based on the load information of an internal combustion engine is supplied to the direct current motor 31 from an ECU, and consequently, the butterfly valve 34 is rotationally controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling control device and a cooling control method for cooling an internal combustion engine such as an automobile engine, and more particularly to improving the responsiveness of temperature control to a cooling medium circulated in the internal combustion engine. Let me
The present invention relates to a cooling control device and method capable of improving the control accuracy.

[0002]

2. Description of the Related Art In an internal combustion engine (hereinafter referred to as an engine) used for an automobile or the like, a water-cooled cooling device using a radiator is generally used for cooling the engine. In this type of cooling device, a thermostat is used to control the temperature of the cooling water, and when the cooling water is lower than a predetermined temperature, the cooling water flows to the bypass passage by the action of the thermostat. The cooling water is circulated without passing through the radiator. FIG.
Reference numeral 9 denotes the configuration of the engine. Reference numeral 1 denotes an engine including a cylinder block 1a and a cylinder head 1b.
a and a fluid passage indicated by an arrow c are formed in the cylinder head 1b. Reference numeral 2 denotes a heat exchanger, that is, a radiator. The radiator 2 has a fluid passage 2c as is well known, and a cooling water inlet 2a and a cooling water outlet 2b of the radiator 2 Is connected to a cooling water passage 3 for circulating cooling water.

The cooling water passage 3 has an outlet cooling water passage 3a communicating from a cooling water outflow portion 1d provided in the upper part of the engine 1 to a cooling water inflow portion 2a provided in the upper part of the radiator 2; An inflow cooling water passage 3b communicating from a cooling water outflow portion 2b provided at a lower portion to a cooling water inflow portion 1e provided at a lower portion of the engine 1, and a bypass water passage connecting midway portions of the two cooling water passages 3a, 3b. 3c. Further, a thermostat 4 is disposed at a branch portion of the cooling water channel 3 between the outflow-side cooling water channel 3a and the bypass water channel 3c. The thermostat 4 has a built-in thermal expansion body (for example, wax) that expands and contracts due to a change in cooling water temperature, and when the cooling water temperature is high (for example, 80 ° C. or higher), the thermal expansion body expands. The valve is opened to allow the cooling water flowing out of the outflow portion 1d of the engine 1 to flow into the radiator 2 through the outflow-side cooling water passage 3a, and the cooling water that has been radiated by the radiator 2 and has a low temperature flows out of the outflow portion 2b. Cooling water passage 3b
Through the inflow portion 1e of the engine 1 so as to flow into the engine 1.

When the temperature of the cooling water is low, the valve of the thermostat 4 is closed by the contraction of the thermal expansion member, and the cooling water flowing out of the outlet 1d of the engine 1 is supplied to the bypass water passage 3d.
c, it flows from the inflow portion 1e of the engine 1 to the cooling passage c in the engine 1. FIG.
In FIG. 9, reference numeral 5 denotes a water pump disposed in the inflow portion 1e of the engine 1, which rotates a rotation shaft by rotation of a crankshaft (not shown) of the engine 1 to forcibly circulate cooling water. Reference numeral 6 denotes a fan unit for forcing cooling air into the radiator 2 and includes a cooling fan 6a and a fan motor 6b for rotating the fan.

[0005] The valve-opening and valve-closing action of the thermostat as described above is determined by the temperature of the cooling water and is caused by the expansion and contraction action of a thermal expansion body such as wax. Temperature and temperature at valve closing are not constant. In other words, the thermal expansion body such as wax requires a certain period of time from the time when the temperature of the cooling water changes to the time when the valve operates. Has characteristics. For this reason, there is a technical problem that it is difficult to adjust the cooling water to a desired constant temperature range.

Therefore, there has been proposed a device in which the flow rate of the cooling water is electrically controlled without using the valve opening and valve closing action of a thermal expansion body such as wax. This is to control the rotation angle of the butterfly valve by, for example, a stepping motor. In this case, the thermostat 4 in FIG. 19 is omitted, and a valve unit 7 having a butterfly valve instead of the thermostat 4 is arranged in the outflow-side cooling water passage 3a as shown by a broken line in FIG. FIG. 20 shows an example of the valve unit 7, in which a circular flat butterfly valve 7a is supported in a cooling water passage 3a by a support shaft 7b so as to be rotatable. A worm wheel 7c is attached to one end of the support shaft 7b, and a worm 7e fitted on a rotary drive shaft of a motor 7d is configured to mesh with the worm wheel 7c.

The motor 7d is supplied with an operating current for rotating its drive shaft forward and backward by a control unit (ECU) for controlling the operating state of the entire engine. Accordingly, when a current for rotating the drive shaft forward is supplied to the motor 7d by the action of the ECU, the worm 7
e and the well-known deceleration action of the worm wheel 7c causes the support shaft 7b of the butterfly valve 7a to rotate in one direction, whereby the surface direction of the butterfly valve 7a is rotated in the same direction as the water channel direction of the cooling water channel 3a to open the valve. It is said. Also, E
When a current for reversing the drive shaft is supplied to the motor 7d by the action of the CU, the support shaft 7b of the butterfly valve 7a is rotated in the other direction, whereby the surface direction of the butterfly valve 7a is changed to the water channel direction of the cooling water channel 3a. , And the valve is closed. The ECU is supplied with information relating to, for example, the temperature of the cooling water of the engine, and is configured to control the temperature of the cooling water by controlling the motor using this information.

[0008]

By the way, in the cooling control device using the butterfly valve as described above, for example, a temperature detecting element (not shown) such as a thermistor is provided in a part of the cooling water channel of the engine 1. The motor 7d is arranged based on the cooling water temperature detected by the temperature detecting element.
Is configured to be driven. Therefore, according to such a configuration, it is possible to reduce the influence of the hysteresis characteristic to a certain extent as in the case of using a thermostat using a thermal expansion body as in the former case. However,
After the temperature detection element detects that the temperature of the cooling water has changed, the valve angle is controlled by the ECU based on the temperature detection element. This is the same as the former in what is called follow-up control. Therefore, even in the cooling control device using the butterfly valve as described above, the so-called hunting phenomenon in which the temperature of the cooling water constantly moves up and down around the specific temperature Tc is unavoidable, and therefore, stable and accurate Good control becomes difficult.

In general, driving an automobile engine in a high temperature state that does not cause overheating can improve fuel efficiency and suppress generation of harmful gas to some extent. However, in the case where the hunting occurs as described above, the cooling water temperature Tc has to be set lower in order to avoid the worst case in which the engine is overheated, and therefore fuel economy must be sacrificed. There was a technical problem that it could not be obtained. On the other hand, the actuator for rotating the Batarai valve is provided with, for example, a stepping motor as described above, and is driven by a pulse-like control signal provided from the ECU to rotate the Batarai valve. .

In this type of stepping motor,
As is well known, the maximum rotational speed (rpm /
min) is considerably lower than that of the DC motor. Therefore, if it is configured to obtain a predetermined rotation torque by using the worm gear or other reduction gear as described above, and set to give an appropriate rotation speed to the Batterai valve,
Inevitably, a high torque is required for the motor itself, which has a technical problem of increasing the size of the entire actuator. In addition, for example, in the case where a failure of the motor or a failure occurs in the reduction gear portion, the opening / closing operation of the butterfly valve becomes impossible. For example, if the above-mentioned failure or failure occurs in a state where the butterfly valve is closed or at an intermediate angle close to the closed state, the engine is not sufficiently cooled, and the engine is overheated while the driver does not recognize it. Technical issues such as

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned technical problems. In particular, the present invention performs temperature control in a state where the temperature change of cooling water is predicted, and the hunting described above occurs. It is an object of the present invention to provide a cooling control device and a control method with improved control accuracy without the need. Another object of the present invention is to provide a cooling control device capable of preventing a problem such as overheating of an engine due to occurrence of a failure in a driving device portion of a flow control valve or the like and exhibiting a fail-safe function. It is.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a cooling control apparatus for an internal combustion engine according to the present invention comprises a fluid passage formed in an internal combustion engine and a fluid passage formed in a heat exchanger. A cooling control device for an internal combustion engine, wherein a cooling medium circulation path is formed between the cooling medium and the heat generated in the internal combustion engine by circulating the cooling medium through the circulation path to be radiated by the heat exchanger. Flow rate control means for controlling the flow rate of the cooling medium in the circulation path between the internal combustion engine and the heat exchanger in accordance with the degree of valve opening,
Information extracting means for extracting at least load information for the internal combustion engine and temperature information of the cooling medium; determining a target set temperature of the cooling medium corresponding to the load information; And a control unit for generating a control signal for the actuator of the flow rate control means based on the relationship between the temperature deviation and the rate of change of the temperature deviation.

In this case, the load information is generated based at least on the rotational speed of the internal combustion engine and the opening information of the throttle valve. Then, the control unit includes a first control signal generating mode for generating a control signal for the actuator when the rate of change of the temperature deviation and the temperature deviation is smaller than the predetermined change speed of the temperature deviation and the temperature deviation A second control signal generation mode for generating a control signal for the actuator in a case where the value is larger than a predetermined value is configured to be executed. In this case, preferably, the first control signal generation mode includes an integral control element for continuously and minutely changing the flow rate of the cooling medium by the flow rate control means in accordance with the temperature deviation, every unit time. The control signal generation mode is configured to generate an actuator control signal based on the cooling medium flow rate setting data read from the map described in correspondence with the temperature deviation and the temperature deviation change rate.

In a further preferred embodiment, a sensor for indicating the flow rate of the cooling medium by the flow rate control means is further provided, and information obtained by the sensor is configured to be used for arithmetic processing in the control unit. . In a preferred embodiment, the flow rate control means is constituted by a butterfly valve which is arranged in a cylindrical cooling medium passage and whose angle in a plane direction with respect to a flowing direction of the cooling medium is variable. As the sensor indicating the flow rate of the cooling medium, an angle sensor that generates information on the rotation angle of the butterfly valve is used.

In a preferred embodiment, the actuator includes a DC motor that is driven to rotate based on a control signal from the control unit, a clutch mechanism that transmits or releases a rotational driving force of the DC motor, The flow rate control means includes a return spring for urging the flow rate control means in a valve opening direction. The speed reduction mechanism is configured to reduce the rotation speed of the DC motor via the clutch mechanism. The clutch mechanism is configured to be in a released state in response to an abnormal state output from the control unit, and configured to hold the flow control means in an open state by a return spring.

According to another aspect of the present invention, there is provided a cooling control method for an internal combustion engine, wherein the cooling is performed between a fluid passage formed in the internal combustion engine and a fluid passage formed in a heat exchanger. A cooling control method for an internal combustion engine configured to form a circulation path of a medium and to radiate heat generated in the internal combustion engine by the heat exchanger by circulating a cooling medium through the flow control means in the circulation path. Capturing at least load information for the internal combustion engine and temperature information of the cooling medium; obtaining a target set temperature of the cooling medium corresponding to the load information; and temperature information and a target set temperature of the cooling medium. Calculating the temperature deviation of the temperature deviation, the step of calculating the temperature deviation and the rate of change of the temperature deviation, and the relationship between the temperature deviation and the rate of change of the temperature deviation Generating a control signal for driving the actuator of the flow control means based on the control signal, and driving the actuator based on the control signal, and performing flow control of the cooling medium flowing into the heat exchanger. I do.

In this case, preferably, the step of generating a control signal for driving the actuator further includes a step of determining whether or not the temperature deviation and the rate of change of the temperature deviation are smaller than a predetermined value. When it is determined that the rate of change between the deviation and the temperature deviation is smaller than a predetermined value, an integral control element for continuously and minutely changing the flow rate of the cooling medium by the flow rate control means in accordance with the temperature deviation per unit time is provided. Executing a step of generating a control signal including the temperature deviation and the rate of change of the temperature deviation when it is determined that the rate of change of the temperature deviation is not smaller than a predetermined value. A step of generating a control signal based on the read flow rate setting data of the cooling medium is executed.

According to the above configuration and control method, the target set temperature of the cooling water as the cooling medium is determined based on, for example, load information obtained from the rotation speed of the internal combustion engine and the angle information of the throttle valve. Further, a temperature deviation is obtained in a predetermined time unit based on the target set temperature and the temperature information of the cooling water, and a change speed of the temperature deviation is also obtained. Then, a control signal is generated using the temperature deviation and the rate of change of the temperature deviation as parameters, and the control signal is supplied to an actuator that drives, for example, a butterfly valve as flow rate control means. In this case, the control signal generation mode is changed according to the magnitude of the temperature deviation and the rate of change of the temperature deviation. If the magnitude of the temperature deviation and the rate of change of the temperature deviation are smaller than a predetermined value, the cooling water The rotation angle of the butterfly valve is controlled by PI control including an integral control element for continuously and minutely changing the flow rate every unit time.

If the magnitude of the temperature deviation and the rate of change of the temperature deviation are larger than a predetermined value, the flow rate of the cooling medium read from the map described in correspondence with the temperature deviation and the rate of change of the temperature deviation. Based on the setting data, responsive control for quickly driving the butterfly valve is performed. Thereby, temperature control is performed in a state where the temperature transition of the cooling water is predicted, and by using the above-described PI control together, it is possible to obtain preferable control accuracy in which the occurrence of significant hunting of the cooling water is prevented. In addition, an actuator for rotationally driving the butterfly valve includes a DC motor, a clutch mechanism, and a deceleration mechanism, and drives the butterfly valve based on the control signal described above.

In this case, in particular, by using a DC motor, it is possible to utilize the high-speed rotation characteristic which is a characteristic of the DC motor, and to drive the butterfly valve with a sufficient rotational torque by a combination of a small DC motor and the aforementioned reduction mechanism. can do. Therefore, it is possible to reduce the size of the entire actuator. Further, by providing a return spring for biasing the butterfly valve to the open state and providing the actuator with a clutch mechanism, the valve opening action by the return spring in an abnormal condition can be smoothly performed.
Furthermore, the configuration in which the clutch mechanism is interposed between the DC motor and the speed reduction mechanism makes it possible to extremely reduce the driving force applied to the clutch mechanism, that is, the torque, thereby preventing the clutch mechanism from slipping and wearing. Therefore, the clutch mechanism can be downsized, which can contribute to the downsizing of the actuator.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a cooling control device for an internal combustion engine according to the present invention will be described based on an embodiment shown in the drawings. FIG. 1 shows an entire configuration applied to a cooling control device for an automobile engine. In FIG. 1, the same reference numerals as those in the conventional apparatus shown in FIG. 19 denote corresponding parts, respectively, and accordingly, the description of the individual configuration and operation will be appropriately omitted. As shown in FIG. 1, the cooling water is disposed between an outflow portion 1 d of cooling water provided at an upper portion of an engine 1 as an internal combustion engine and an inflow portion 2 a of cooling water provided at an upper portion of a radiator 2 as a heat exchanger. The flow control unit 11 is connected to the outlet-side cooling water channel 3a by a flange. Thereby, the flow control unit 1
1, the cooling medium, that is, the cooling water circulation path 12
Are formed.

A cooling water outflow portion 1d of the engine 1 has a temperature detecting element 13 such as a thermistor.
Is arranged. The value detected by the temperature detecting element 13 is converted into data recognizable by the control unit (ECU) 15 by the converter 14 and supplied to the control unit (ECU) 15 for controlling the operating state of the entire engine. Have been. Further, in the embodiment shown in FIG. 1, the opening degree information from a throttle position sensor 17 for detecting the opening degree of the throttle valve 16 of the engine 1 is also supplied to the control unit 15. Although not shown, the control unit 15 is also configured to be supplied with information such as the number of revolutions of the engine. On the other hand, a control signal is supplied from the control unit 15 to the motor control circuit 18 and the clutch control circuit 19. The motor control circuit 18 and the clutch control circuit 19
The current supplied from 0 is controlled, and a control current is supplied to a DC motor control circuit and a clutch control circuit, which will be described later, provided in the flow control unit 11.

FIG. 2 schematically shows the structure of the flow rate control unit 11, a part of which is shown in a sectional view. The flow control unit 11 includes a butterfly valve and an actuator for driving the butterfly valve. First, a DC motor 31 is provided in the actuator, and a first clutch disc 32a constituting a clutch mechanism 32 is coupled to a rotating shaft 31a of the DC motor 31 in a rotating direction of the rotating shaft 31a. It is mounted so that it can slide in the direction. FIG. 3 shows a state where the AA 'portion in FIG. 2 is viewed in the direction of the arrow. That is, the rotary shaft 31a of the motor has a hexagonal outer shape as shown in the figure, while the rotary shaft 31a of the motor is provided at the center of the first clutch disc 32a.
A hexagonal hole is formed so as to surround. With this configuration, the first clutch disc 32a is coupled in the rotation direction of the rotation shaft 31a and acts so as to be slidable in the axial direction.

Returning to FIG. 2, an annular groove 32b is formed on the peripheral side surface of the first clutch disc 32a, and the distal end of the actuator 32d of the electromagnetic plunger 32c is loosely fitted in the groove 32b. Is configured. A coil spring 32e is attached to the plunger 32c. In a normal state in which the plunger 32c is not energized by the expanding action of the coil spring 32e,
As shown in FIG. 2, the first clutch board 32a is drawn into the motor 31 side. The first clutch board 3
A second clutch disc 32f is arranged so as to face 2a, and the second clutch disc 32f is fixed to an input-side rotating shaft 33b constituting the speed reduction mechanism 33. The deceleration mechanism 33 is configured such that the input side rotation shaft 33b and the intermediate rotation shaft 33 are supported by respective bearings attached to a case 33a.
c, The output side rotation shaft 33d is arranged in parallel with each other. A pinion 33e is provided on the input side rotation shaft 33b.
Is fixed, and the spur gear 33 is fixed to the intermediate rotation shaft 33c.
The pinion 33g fixed to the intermediate rotation shaft 33c is meshed with the spur gear 33h fixed to the output side rotation shaft 33d.

With this configuration, the speed reduction mechanism 33 is configured such that the speed reduction ratio is, for example, about 1/50.
An output-side rotation shaft 33 d of the speed reduction mechanism 33 is connected to a drive shaft of the flow control valve 34. Flow control valve 34
Is constituted by a flat butterfly valve 34b arranged in a cylindrical cooling medium passage 34a. The butterfly valve 34b is configured such that the angle in the plane direction with respect to the flow direction of the cooling water is controlled by the rotation angle of the support shaft 34c as a drive shaft. That is,
The valve is opened when the angle in the plane direction with respect to the flow direction of the cooling water is about 0 degrees, and the valve is closed when the angle in the plane direction with respect to the flow direction of the cooling water is about 90 degrees. Then, by appropriately setting the intermediate angle, the flow rate of the cooling water is linearly controlled.

A collar 34d is fixed to the support shaft 34c on the speed reduction mechanism 33 side of the support shaft 34c, and a coil-shaped return spring 34e is wound around a peripheral side surface of the collar 34d. . One end of the return spring 34e is engaged with a part of a cylindrical body that forms the cooling medium passage 34a inside, and the other end of the return spring 34e is connected to a protrusion 34f attached to a part of the collar 34d. Is engaged. In this state, the return spring 34e urges the butterfly valve 34b connected to the support shaft 34c so that the butterfly valve 34b is opened. An angle sensor 34g is connected to the other end of the support shaft 34c facing the speed reduction mechanism 33, so that the rotation angle of the butterfly valve 34b can be recognized.

In the flow control unit 11 constructed as described above, the DC motor 31 is configured to receive a drive current from the motor control circuit 18 shown in FIG. 1, and the electromagnetic plunger 32c in the clutch mechanism 32 is provided in the same manner as in FIG.
1 is supplied with a drive current from the clutch control circuit 19, and the data output relating to the rotation angle of the butterfly valve by the angle sensor 34g is supplied to the control unit 15 shown in FIG. Therefore, in the configuration shown in FIG. 2, when the electromagnetic plunger 32c is energized, the actuator 32d moves the first clutch disc 32a to the second clutch disc 32a.
It is moved to the clutch disc 32f side to be in the connected state. When a drive current is supplied to the DC motor 31,
The rotational driving force of the motor 31 is reduced by the reduction mechanism, and rotates the butterfly valve 34b via the support shaft 34c. The rotation of the support shaft 34c causes the angle sensor 34g to feed back data on the rotation angle to the control unit 15.

FIG. 4 is a connection diagram showing the configuration of the motor control circuit 18. As shown in FIG. The motor control circuit 18 includes a first switching element Q1 and a second switching element Q2 which are connected in series between a positive terminal and a negative terminal (earth) of a power supply (battery 20), and between the positive terminal and the negative terminal. The third switching element Q3 and the fourth switching element Q4 connected in series form a bridge circuit. Each of these switching elements is constituted by an NPN-type bipolar transistor. Accordingly, the collectors of the first transistor Q1 and the third transistor Q3 are connected to the positive terminal of the battery 20, and the second transistor Q2 and the fourth transistor Q4
Are connected to ground.

The emitter of the first transistor Q1 and the collector of the second transistor Q3 are connected, and the first
A connection middle point 18a is formed. The emitter of the third transistor Q3 and the collector of the fourth transistor Q4 are connected to form a second connection middle point 18b. A pair of drive current input terminals of the DC motor 31 are connected between the first connection middle point 18a and the second connection middle point 18b, respectively. The first and fourth transistors Q1,
The control pole terminal, ie, the base, of Q4 is coupled together to form an input terminal a, and the bases of the second and third transistors Q2, Q3 are coupled together to form an input terminal b.

FIG. 5 shows a switch control signal which is alternatively supplied from the control unit 15 to the input terminal a and the input terminal b in FIG. This control signal has a PWM pulse waveform, and is configured to be driven for a certain period of time according to the motor rotation direction as shown in the figure. When the valve is closed, a control signal having a large pulse width (W1) is supplied only to the input terminal a, and when the valve is opened, a control signal having a small pulse width (W2) is supplied only to the input terminal b. . That is, when the butterfly valve 34b is to be opened, the valve is effectively driven with a small pulse width by using the torque in the return direction of the return spring 34e.

When the butterfly valve 34b is to be closed, the terminal a shown in FIG.
, A switch control signal having a pulse width shown as (a) is supplied. Therefore, the transistors Q1 and Q4 are turned on by the switch control signal corresponding to the pulse width shown in FIG. 5A, and the motor 31 is driven to rotate in one direction. When the butterfly valve 34b is to be opened, a switch control signal having a pulse width shown at the time of opening (b) in FIG. 5 is supplied to the terminal b shown in FIG. Therefore, transistors Q2 and Q3 are
The ON control is performed by the control signal having the pulse width shown in FIG. 4B, and the motor 31 is driven to rotate in the reverse direction.

FIG. 6 shows the basic configuration of the ECU 15 shown in FIG. The ECU 15 includes a signal processing unit 15a that converts a signal supplied from each sensor into a digital signal or the like that can be recognized by the ECU.
A comparing unit 15b for comparing the input data processed by the processing unit 5a with various types of data described later stored in a table format in the memory 15c; and a signal processing for performing arithmetic processing on the comparison result by the comparing unit 15b and outputting a control signal. It is composed of a part 15d.

The operation of the vehicle engine cooling control device shown in FIGS. 1 to 6 will be described below in accordance with the control flow mainly executed by the ECU 15 shown in FIGS. First, in the flow shown in FIG. 7, when the automobile engine is started, a control signal is supplied from the ECU 15 to the clutch control circuit 19, so that a drive current is supplied to the electromagnetic plunger 32c shown in FIG. 32 is in the transmission state. At the same time, the ECU 15 sends a control signal to the motor control circuit 18 to close the flow control valve in the open state, that is, the butterfly valve 34b. (Step S1) As a result, a control signal having a pulse width (W1) shown in FIG. 5 when the valve is closed is applied to the terminal a in the motor control circuit 18 shown in FIG. Accordingly, the DC motor 31 is driven to rotate, and the butterfly valve 34b is temporarily closed via the speed reduction mechanism 33.

Then, in step S2, the ECU 15
Reads the cooling water temperature (Tws) at the time of starting the engine from the converter 14 receiving the information from the temperature detecting element 13.
Subsequently, in step S3, the ECU 15 determines the engine speed (N), the throttle opening (θT), and the cooling water temperature (T
w). Next, in step S4, the relationship between the cooling water temperature (Tw) and the cooling water temperature at startup (Tws) is determined. That is, when it is determined that the condition of Tw> Tws is No, the process proceeds to step S5, and the motor control circuit 18
, A control signal is sent, and the valve angle is set to a value such that the angle detected by the angle sensor 34g is substantially 90 degrees. As a result, the butterfly valve 34b maintains the closed state. (Step S6)

Then, in step S7, it is determined whether or not the engine has been stopped. If it is determined that the engine has not been stopped (No), the routine returns to step S3 again. If it is determined in step S7 that the engine is stopped (Yes), the process proceeds to step S8, where EC is determined.
U15 stops supplying the control signal to the clutch control circuit 19, so that the operation of the electromagnetic plunger 32c is stopped. As a result, the clutch mechanism 32 is released, and the butterfly valve 34b is opened by the action of the return spring 34e. In step S4, T
If it is determined that the condition of w> Tws is Yes, the process moves to step S9, and the target set water temperature (Ts) corresponding to the engine speed (N) -throttle opening (θT) as the load information of the engine is calculated as shown in FIG. Search from the table shown in.

In the table shown in FIG. 11, the target set water temperature (Ts) is described in a matrix between the engine speed (N) and the throttle opening (θT). In the figure, the relationship between the engine speed (N) and the throttle opening (θT) is considerably coarse for convenience of description on the paper, but is specifically described in a finer state. Further, even in a slightly rough state, a target set water temperature (Ts) that can be practically used can be obtained by performing so-called intermediate interpolation at an intermediate value. this is,
The same applies to the following tables.

Subsequently, in step S10, the temperature deviation (ΔT = Tw−T) is calculated from the cooling water temperature (Tw) and the target set water temperature (Ts) retrieved from the table shown in FIG.
s) is calculated. Then, in step S11, a reference control valve angle (θso) corresponding to the engine speed (N) and the throttle opening (θT) is retrieved from the table shown in FIG. Subsequently, in step S12, a temperature deviation speed (Tv) is calculated from the previous water temperature (Two) and the current water temperature (Tw). That is, step S in FIG.
As shown in FIG. 12, Tv = ΔT / Δt = (Two−Tw)
/ Sec is executed. The temperature deviation obtained by the steps S10 and S12 (Δ
In step S13, the two data of T) and the temperature deviation speed (Tv) are respectively given predetermined temperature deviation values (Δ
TA) and a predetermined temperature deviation speed value (Tv). That is, as shown in FIG. 7, ΔT ≦ ΔTA, Tv
A comparison operation of ≤TvA is performed.

The predetermined temperature deviation value (ΔTA) and the predetermined temperature deviation speed value (Tv) are set to values having relatively low deviation components surrounded by thick lines in a table described later. If it is determined in S13 that the value is not smaller than the predetermined value (No), the process proceeds to step S21 shown in FIG. Step S21 shown in FIG.
Steps S25 to S25 are routines of quick response control for relatively quickly executing the flow rate control of the cooling water by the flow rate control valve. In step S21, the control valve set angle (θs) corresponding to the temperature deviation (ΔT) obtained in step S10 and the temperature deviation speed (Tv) obtained in step S12 is searched from the table shown in FIG.

The table shown in FIG. 13 has a temperature deviation (ΔT) and a temperature deviation speed (Tv) similar to the above table.
The control valve set angle (θs) is described in a matrix between the two. In the table, the range (ΔT4) in which the value of the temperature deviation (ΔT) is small and the range (Tv4) in which the value of the temperature deviation speed (Tv) is small are defined by the predetermined temperature deviation value (ΔTA) and the predetermined value. Is set as the temperature deviation speed value (Tv). Step S
At 22, the calculation of the total control valve angle (θ) is performed. This is because θ = θso ± θ between the reference control valve angle (θso) retrieved in step S11 and the control valve set angle (θs) retrieved in step S21.
The operation of s is performed.

Then, in step S23, a calculation for selecting the rotation direction of the motor, that is, a calculation of Δθ = θv−θ is performed. Note that θv used in this calculation is obtained from the angle sensor 34g for detecting the control valve angle shown in FIG. Then, the rotation direction of the motor is determined according to the positive or negative value of the result of the calculation.
Subsequently, the process proceeds to step S24, where the DC motor, that is, the DC motor 31 shown in FIG. 2 is driven. In this case, if Δθ is large according to the value of Δθ, a large duty pulse corresponding thereto is generated, and if Δθ is small, a small duty pulse corresponding thereto is generated, and the PWM signal Drives the DC motor. As a result, in step S25, the butterfly valve 34b, which is a flow control valve, is rotated, and after passing through the above routine,
The process returns to step S7 in FIG.

On the other hand, as a result of the comparison operation in step S13 in FIG. 7, the temperature deviation (ΔT) and the temperature deviation speed (T
When it is determined that v) is equal to or less than a predetermined range (Yes),
The process moves to step S31 in FIG. Steps S31 to S40 shown in FIG. 9 are routines for executing PI control including an integral control element for continuously and minutely changing the flow rate control of the cooling water by the flow rate control valve every unit time. In step S31, the proportional opening value (θsp) is searched from the table of the proportional opening value (θsp) corresponding to the temperature deviation (ΔT) shown in FIG. Subsequently, in step S32, FIG. 15 corresponding to the temperature deviation (ΔT)
The integrated opening value (θsi) is searched from the table of the integrated opening value (θsi) shown in FIG. Then, the process proceeds to step S33, and it is determined whether or not the value of the temperature deviation speed (Tv) obtained in step S12 is "0". If it is determined that the value of the temperature deviation speed Tv is “0”, the process proceeds to step S37 described later. If it is determined that the value of the temperature deviation speed Tv is not “0”, the process proceeds to step S34.

In step S34, step S1
The value of the temperature deviation ΔT obtained at 0 is determined. If it is determined in this step S34 that ΔT> 0, the process proceeds to step S35, if it is determined that ΔT <0, the process proceeds to step S36, and if it is determined that ΔT = 0, the process proceeds to step S37. In step S35, a value θ for decreasing the control valve opening is calculated as the control valve opening calculation. Here, the reference control valve opening θso retrieved in step S11, the proportional opening value θsp retrieved in step S31, and step S32
From the integrated opening value θsi found in the above, θ = θso
The calculation of − (θsp + θsi) is performed. In step S36, a value θ for increasing the control valve opening is calculated as the control valve opening calculation. Here, θ = θ
The calculation of so + (θsp + θsi) is performed. Further, in the case of step S37, the action of bringing the previous control valve angle θ as it is is performed.

Then, the process proceeds to step S38, where Δθ = θv−θ is obtained based on the control valve angle (θ) obtained in steps S35 to S37 and the control valve opening (θv) obtained from the control valve angle sensor 34g. Is calculated. This is the same operation as in step S23 described above, and the rotation direction of the motor is determined based on the result. Then, step S39 and step S40
Is executed, the opening of the flow control valve is controlled.
The operation of steps S39 and S40 is the same as that of steps S24 and S25 described above, and a description thereof will be omitted. After the above routine, the process returns to step S7 in FIG. 7, and the above routine is repeated until the engine is stopped.

With the above operation, the temperature of the cooling water is controlled in a state where the temperature transition of the cooling water is predicted from the load information on the engine. Depending on the situation, the flow control valve is controlled to open and close by the control signals obtained in the first control signal generation mode and the second control signal generation mode. As a result, the responsiveness of the control valve is improved and the cooling water is improved. The control accuracy can be greatly increased.

The above-described flow shown in FIGS. 7 to 9 uses the control valve opening θs set corresponding to the temperature deviation ΔT and the temperature change rate Tv in order to improve the response of the flow control valve. The reading and the opening of the control valve are controlled. The flow shown in FIG. 10 can be used to more easily implement this method. FIG. 10 can be used by replacing the step S13 in FIG. 7 with the steps S21 to S25 shown in FIG. That is, step S51 in FIG. 10 is the same as step S13 in FIG. If No is determined in this step S51, in step S52, the engine speed (N) -throttle opening (θ) as the load information of the engine is determined.
The control valve angle θs ′ corresponding to T) is retrieved from the table shown in FIG. Then, in step S53, a calculation for selecting the rotation direction of the motor, that is, a calculation of Δθ = θv−θs ′ is performed as in the case of step S23. The rotation direction of the motor is determined according to the positive or negative value of the result of this calculation.

The operation of the following steps S54 and S55 is the same as that of steps S24 and S25, and a description thereof will be omitted. Then, step S5
6, it is determined whether or not the flow control valve opening θv obtained from the angle sensor 34g is equal to the control valve set angle θs ′ obtained in step S52 (θs ′ = θv?). ), The process returns to step S7 shown in FIG. On the other hand, when it is determined that they are equal (Yes), the flow shifts to step S31 in FIG. 9, and the PI control is executed.

In each of the flow charts shown in FIGS. 7 to 9 and the flow chart shown in FIG. 10, the angle of the butterfly valve 34b as the flow control valve is determined by the angle sensor 34g and the flow control valve opening θv. The same control can be executed without using the flow control valve opening degree θv. That is, when the angle sensor is used, the flow control valve opening degree θv is basically controlled to the target set water temperature Ts as a control deviation signal, and when the angle sensor is not used, the flow rate is directly based on the temperature deviation signal ΔT. Thus, the DC motor can be controlled by driving with a PI duty pulse. Therefore, when the control valve angle sensor is not used, a similar result can be obtained by replacing the table shown in FIG. 13 with a DC motor drive PI duty value table and performing control.

FIG. 17 shows an example of a proportional duty table corresponding to the temperature deviation signal ΔT used for this. FIG. 18 shows an integration duty table corresponding to the temperature deviation signal ΔT used for this. Is shown. By referring to these correspondence tables and controlling the duty ratio of the PWM signal applied to the bridge type DC motor drive circuit shown in FIG. 4 with time, the same operation and effect can be obtained.

In the control unit 15, the actual cooling water temperature Tw obtained by the temperature detecting element 13 is obtained.
Is compared with the target set water temperature Ts, and when the difference ΔT becomes larger than a predetermined value after a certain period of time,
That is, when the temperature deviates from the predetermined temperature range, an abnormal state output can be generated. The occurrence of this abnormal state output causes the clutch control circuit 19 to control the clutch mechanism 32 to be released, so that the butterfly valve 34b can be opened by the action of the return spring 34e. Therefore, the circulation of the cooling water is promoted, and it is possible to prevent the engine from being overheated. Although the above has been described based on the embodiment in which the cooling control device of the present invention is applied to an automobile engine,
The present invention is not limited to such specific ones, and similar effects can be obtained by applying the present invention to other internal combustion engines.

[0050]

As is apparent from the above description, according to the cooling control apparatus and the cooling control method for an internal combustion engine according to the present invention, the target set temperature of the cooling medium is obtained based on at least the load information for the internal combustion engine. Since the temperature deviation and the rate of change of the temperature deviation are determined based on the target set temperature and the actual temperature of the cooling medium, an optimal control mode can be selected based on those numerical values. And the first
It is possible to execute the PI control as the control signal generation mode and the quick response control as the second control signal generation mode, and perform highly accurate temperature management in a state where the temperature transition of the cooling water is predicted. Becomes possible. Therefore, it is possible to prevent the occurrence of hunting of the cooling water temperature, and it is possible to reduce fuel consumption and harmful exhaust gas.

Further, since the actuator for controlling the flow rate control means is constituted by a DC motor, a clutch mechanism and a speed reduction mechanism, it is possible to reduce the size of the whole while obtaining a sufficient drive torque of the flow rate control means. For example, when used in an automobile engine, the occupied volume can be reduced. In addition, by using a return spring that urges the flow control means in the valve opening direction, problems such as overheating of the engine due to occurrence of a failure can be prevented beforehand, and a fail-safe function can be exhibited.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment in which a cooling control device according to the present invention is applied to an automobile engine.

FIG. 2 is a configuration diagram showing a flow control unit used in the apparatus shown in FIG. 1 in a partially sectional state.

FIG. 3 is an enlarged cross-sectional view taken along the line AA ′ in FIG. 2;

FIG. 4 is a connection diagram showing a motor drive circuit used in the device shown in FIG. 1;

FIG. 5 is a waveform chart showing an example of a control signal applied to the motor drive circuit shown in FIG.

FIG. 6 is a block diagram showing a configuration of an engine control unit (ECU) shown in FIG.

FIG. 7 is a flowchart illustrating an operation performed by the ECU.

FIG. 8 is a flowchart following the flowchart shown in FIG. 7, mainly for explaining the action of quick response control;

FIG. 9 is a flowchart following the flowchart shown in FIG. 7, mainly for explaining the operation of PI control;

FIG. 10 is a flowchart showing an example that can be used in place of the flowchart shown in FIG. 8;

11 is a configuration diagram showing an example of a data table used in the processing routine shown in FIG. 7;

FIG. 12 is a configuration diagram illustrating an example of another data table used in the processing routine illustrated in FIG. 7;

13 is a configuration diagram showing an example of a data table used in the processing routine shown in FIG.

14 is a configuration diagram showing an example of a data table used in the processing routine shown in FIG.

FIG. 15 is a configuration diagram showing an example of another data table used in the processing routine shown in FIG. 9;

16 is a configuration diagram showing an example of a data table used in the processing routine shown in FIG.

FIG. 17 is a configuration diagram showing an example of a data table used in another embodiment of the cooling control device according to the present invention.

FIG. 18 is a configuration diagram showing another example of a data table.

FIG. 19 is a configuration diagram showing an example of a conventional cooling device for an automobile engine.

FIG. 20 is a configuration diagram showing an example of a conventional flow control device using a butterfly valve in a partially sectional state.

[Explanation of symbols]

 Reference Signs List 1 internal combustion engine (engine) 2 heat exchanger (radiator) 2c fluid passage 3 cooling water passage 5 water pump 6 fan unit 11 flow control unit 12 cooling medium circulation passage 13 temperature detecting element 15 control unit (ECU) 16 throttle valve 17 throttle position sensor Reference Signs List 18 motor control circuit 19 clutch control circuit 20 battery 31 motor (DC motor) 32 clutch mechanism 32a first clutch board 32c electromagnetic plunger 32f second clutch board 33 speed reduction mechanism 34 flow control valve 34a cooling medium passage 34b butterfly valve 34c spindle 34e Return spring 34g Angle sensor

Claims (10)

[Claims] 1. A cooling medium circulation path is formed between a fluid passage formed in an internal combustion engine and a fluid passage formed in a heat exchanger, and the cooling medium is circulated through the circulation path. A cooling control device for an internal combustion engine configured to radiate heat generated in the heat exchanger by the heat exchanger, wherein a flow rate of a cooling medium in a circulation path between the internal combustion engine and the heat exchanger is controlled according to a valve opening degree. Flow rate control means, at least load information for the internal combustion engine, information extraction means for extracting temperature information of the cooling medium, and a target set temperature of the cooling medium corresponding to the load information, and a temperature of the cooling medium A temperature deviation between the information and the target set temperature is determined, and a control signal for the actuator of the flow rate control means is determined based on the relationship between the temperature deviation and the rate of change of the temperature deviation. A cooling control device for an internal combustion engine, comprising: 2. The cooling control apparatus for an internal combustion engine according to claim 1, wherein the load information is generated based on at least information on a rotational speed of the internal combustion engine and information on an opening degree of a throttle valve. 3. The control unit includes: a first control signal generation mode for generating an actuator control signal when the temperature deviation and the rate of change of the temperature deviation are smaller than a predetermined value; Generating a control signal for the actuator when the change speed is greater than a predetermined value;
The cooling control device for an internal combustion engine according to claim 1 or 2, wherein the control signal generation mode is executed. 4. The first control signal generation mode includes an integral control element for continuously and minutely changing a flow rate of a cooling medium by a flow rate control means per unit time in accordance with the temperature deviation. The second control signal generation mode is configured to generate an actuator control signal based on the coolant flow rate setting data read from the map described in correspondence with the temperature deviation and the temperature deviation change rate. 4. The cooling control device for an internal combustion engine according to claim 3, wherein: 5. A sensor for indicating a flow rate of a cooling medium by the flow rate control means, wherein information obtained by the sensor is used for arithmetic processing in the control unit. The cooling control device for an internal combustion engine according to claim 1. 6. The cooling medium is provided with a butterfly valve disposed in a cylindrical cooling medium passage, the angle of which is variable in a plane direction with respect to a flowing direction of the cooling medium. 6. The cooling control device for an internal combustion engine according to claim 1, wherein the sensor indicating the flow rate is an angle sensor that generates information on a rotation angle of the butterfly valve. 7. The actuator according to claim 1, wherein the actuator includes a DC motor that is rotationally driven based on a control signal from the control unit, a clutch mechanism that transmits or releases a rotational driving force of the DC motor, and the clutch mechanism. 3. A flow rate control means, comprising: a return spring configured to urge the flow rate control means in a valve opening direction. 7. The cooling control device for an internal combustion engine according to 6. 8. The clutch mechanism is configured to be in a disengaged state in response to an abnormal state output from a control unit, and to hold the flow control means in a valve open state by a return spring. 8. The cooling control device for an internal combustion engine according to claim 1. 9. A circulation path for a cooling medium is formed between a fluid passage formed in the internal combustion engine and a fluid passage formed in the heat exchanger, and the cooling medium is supplied through the flow passage control means in the circulation path. A cooling control method for an internal combustion engine configured to radiate heat generated in the internal combustion engine by circulating the heat by the heat exchanger, wherein at least load information for the internal combustion engine and temperature information of the cooling medium are captured. Obtaining a target set temperature of the cooling medium corresponding to the load information; obtaining a temperature deviation between the temperature information of the cooling medium and the target set temperature; and calculating the temperature deviation and a rate of change of the temperature deviation. Generating a control signal for driving an actuator of the flow control means based on the relationship between the temperature deviation and the rate of change of the temperature deviation; Controlling the flow rate of the cooling medium flowing into the heat exchanger by driving the actuator based on the control signal. 10. The method according to claim 10, wherein the step of generating a control signal for driving the actuator further comprises the step of determining whether the temperature deviation and the rate of change of the temperature deviation are smaller than a predetermined value. When it is determined that the change rate of the deviation is smaller than a predetermined value, a control signal including an integral control element for continuously and minutely changing the flow rate of the cooling medium by the flow rate control means in accordance with the temperature deviation every unit time. Is executed, and when it is determined that the temperature deviation and the rate of change of the temperature deviation are not smaller than a predetermined value, the temperature is read from the map described corresponding to the temperature deviation and the rate of change of the temperature deviation. The cooling control method for an internal combustion engine according to claim 9, wherein a step of generating a control signal is performed based on the set flow rate setting data of the cooling medium.