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US20150240702A1 - Cooling control system for engine - Google Patents

Cooling control system for engine Download PDF

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Publication number
US20150240702A1
US20150240702A1 US14/408,328 US201214408328A US2015240702A1 US 20150240702 A1 US20150240702 A1 US 20150240702A1 US 201214408328 A US201214408328 A US 201214408328A US 2015240702 A1 US2015240702 A1 US 2015240702A1
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US
United States
Prior art keywords
cooling
water
clogging
amount
engine
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US14/408,328
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English (en)
Inventor
Yohei Hosokawa
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toyota Motor Corp
Original Assignee
Toyota Motor Corp
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Filing date
Publication date
Application filed by Toyota Motor Corp filed Critical Toyota Motor Corp
Assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA reassignment TOYOTA JIDOSHA KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HOSOKAWA, YOHEI
Publication of US20150240702A1 publication Critical patent/US20150240702A1/en
Abandoned legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P7/00—Controlling of coolant flow
    • F01P7/14—Controlling of coolant flow the coolant being liquid
    • F01P7/16—Controlling of coolant flow the coolant being liquid by thermostatic control
    • F01P7/165—Controlling of coolant flow the coolant being liquid by thermostatic control characterised by systems with two or more loops
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P11/00—Component parts, details, or accessories not provided for in, or of interest apart from, groups F01P1/00 - F01P9/00
    • F01P11/14—Indicating devices; Other safety devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P3/00—Liquid cooling
    • F01P3/20—Cooling circuits not specific to a single part of engine or machine
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P5/00—Pumping cooling-air or liquid coolants
    • F01P5/10—Pumping liquid coolant; Arrangements of coolant pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P7/00—Controlling of coolant flow
    • F01P7/14—Controlling of coolant flow the coolant being liquid
    • F01P7/16—Controlling of coolant flow the coolant being liquid by thermostatic control
    • F01P7/167—Controlling of coolant flow the coolant being liquid by thermostatic control by adjusting the pre-set temperature according to engine parameters, e.g. engine load, engine speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P2023/00—Signal processing; Details thereof
    • F01P2023/08—Microprocessor; Microcomputer
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P2025/00—Measuring
    • F01P2025/60—Operating parameters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P2031/00—Fail safe
    • F01P2031/30—Cooling after the engine is stopped
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P2050/00—Applications
    • F01P2050/24—Hybrid vehicles

Definitions

  • the present invention relates to a controller for a cooling system of an internal combustion engine, and more particularly, to a system for controlling circulation of cooling water.
  • An internal combustion engine is heated by burning fuel, and if a temperature thereof is raised excessively, an abnormal combustion is caused and an energy efficiency of the engine is worsened. Therefore, the engine is provided with a cooling system.
  • the engine is cooled by a water cooling method, an oil cooling method, and an air cooling method. The abnormal combustion would be caused if the engine is cooled insufficiently, and by contrast, fuel combustion would be hindered if the engine is cooled excessively regardless of the cooling method.
  • Japanese Patent No. 4883225 describes a cooling system for a vehicle comprised of a first water circuit for circulating cooling water through an internal combustion engine, and a second water circuit for circulating the cooling water through a waste heat recovery system without passing through the internal combustion engine.
  • a flow rate of the cooling water circulating in the first water circuit is reduced by reducing an opening degree of a valve, and the cooling waters in those circuits are mixed by increasing an opening degree of the valve.
  • a valve element of the valve has a hole for letting through the cooling water even if the valve is closed.
  • the cooling system is configured to judge the valve stuck at a closing position if a temperature of the water in the first cooling circuit is higher than a predetermined value, and a difference between temperatures of the cooling waters in the first cooling circuit and the second cooling water circuit is greater than a predetermined another value.
  • Japanese Patent Laid-Open No. 2007-46469 describes a waste heat recovery system having a cooling passage branching out of a radiation circuit for cooling an engine to let the cooling water through a heat recovery device.
  • a valve is disposed on the cooling passage, and the valve is comprised of a through hole for flowing cooling water, and a narrow hole perpendicular to the through hole. Given that the valve is turned to be opened, the through hole is connected to the cooling passage so that the cooling water is allowed to flow through the cooling passage. By contrast, given that the valve is turned to be closed, the through hole is oriented to be perpendicular to the cooling passage. In this case, however, the narrow hole is connected to the cooling passage so that the cooling water is still allowed to be delivered to the cooling passage in a small amount through the narrow hole.
  • the cooling water is still allowed to flow through the hole formed in the valve element even if a valve sticks at a position where an opening degree of the valve is narrow. However, if the hole is clogged by foreign matter, the cooling water would not be allowed to circulate within the first cooling circuit.
  • the cooling control system is comprised of: a cooling circuit for circulating cooling water via a water pump and the engine to cool the engine; a bypass circuit for circulating the cooling water without passing through the engine; a first temperature sensor that is disposed on the cooling circuit to detect a temperature of the cooling water flowing therethrough; a second temperature sensor that is disposed on the bypass circuit to detect a temperature of the cooling water flowing therethrough; a switching valve that is closed to reduce a flow rate of the cooling water flowing through the cooling circuit, and that is opened to increase the flow rate of the cooling water flowing through the cooling circuit; and a water passage that allows the cooling water to flow through the cooling circuit in a small amount when the switching valve is closed.
  • the cooling control system is provided with an estimation means that is configured to estimate an amount of clogging of the water passage based on a temporal change in a temperature difference between a temperature of the cooling water detected by the first temperature sensor and a temperature of the cooling water detected by the second temperature sensor, under a condition in that the engine is stopped, the switching valve is closed, and the water pump is driven.
  • the estimation means may be configured to estimate the amount of clogging of the water passage by subtracting the temperature difference of a case in which the water pump is not driven from the temperature difference of a case in which the water pump is driven, in case an external temperature is lower than a predetermined temperature.
  • the estimation means may also be configured to estimate a current amount of clogging of the water passage while reducing a drive frequency of the water pump to be less than that of the previous case if a current estimated value of the amount of clogging is smaller than a first threshold value. In this case, if the current estimated value of the amount of clogging is larger than the first threshold value, the estimation means estimates a current amount of clogging of the water passage while increasing the drive frequency of the water pump to be more than that of the previous case.
  • the estimation means may also be configured to estimate the amount of clogging of the water passage by increasing the drive frequency of the water pump with an increase in a speed of a vehicle having the engine.
  • the estimation means may also be configured to estimate the amount of clogging of the water passage while increasing the drive frequency of the water pump if the estimated value of the amount of clogging is larger than the first threshold value but smaller than a second threshold value. In this case, the estimation means opens the switching valve if the estimated value of the amount of clogging is smaller than the second threshold value.
  • the control system is configure to estimate an amount of clogging of the water passage based on such temporal change in the temperature difference so that an accuracy for estimating the amount of clogging can be improved.
  • the drive frequency of the water pump is reduced to be less than the previous value if a current estimated value of the amount of clogging is smaller than a first threshold value. Therefore, accuracy for estimating a current amount of clogging can be improved in comparison with that for estimating a previous amount of clogging.
  • the cooling control system of the present invention may be applied to a hybrid vehicle in which a prime mover is comprised of an internal combustion engine and an electric motor.
  • a prime mover is comprised of an internal combustion engine and an electric motor.
  • the vehicle In this case, therefore, the amount of clogging can be estimated promptly by increasing the drive frequency of the water pump.
  • the vehicle is powered mainly by the motor rather than the engine. In this case, therefore, the accuracy for estimating the amount of clogging can be improved by reducing the drive frequency of the water pump.
  • the switching valve is opened under a condition where the engine has not yet been warmed-up sufficiently and the amount of clogging of the water passage is larger than the first threshold value but smaller than a second threshold value, the engine may be cooled overly. In this case, therefore, a flow rate of the cooling water circulating within the cooling circuit is increased by increasing the drive frequency of the water pump. If the amount of clogging of the water passage is larger than the second threshold value, the flow rate of the cooling water circulating within the cooling circuit is increased by opening the switching valve.
  • FIG. 1 is a flowchart showing a first example of a control carried out by the cooling control system of the present invention.
  • FIG. 2 is an example of a map determining waiting time for commencement of temperature change in the cooling water with respect to a duty cycle.
  • FIG. 3 is a graph indicating a relation between an initial temperature difference ⁇ Tini and a current temperature difference ⁇ Tnow.
  • FIG. 4 is an example of a map determining a clogging amount with respect to a temperature difference ⁇ Td 1 .
  • FIG. 5 is a flowchart showing a second example of a control carried out by the cooling control system of the present invention.
  • FIG. 6 is an example of a map determining a clogging amount with respect to a temperature difference ⁇ Td 2 .
  • FIG. 7 is a flowchart showing a third example of a control carried out by the cooling control system of the present invention.
  • FIG. 8 is a flowchart showing a fourth example of a control carried out by the cooling control system of the present invention.
  • FIG. 9 is an example of a map determining a pulse duty of a water pump with respect to a vehicle speed.
  • FIG. 10 is a flowchart showing a fifth example of a control carried out by the cooling control system of the present invention.
  • FIG. 11 is an example of a map for correcting a pulse duty of a water pump with respect to the clogging amount.
  • FIG. 12 is a view schematically showing a preferred example of the cooling control system of engine according to the present invention.
  • the cooling control system is comprised of a circuit for circulating cooling water passing through an internal combustion engine of a vehicle, and a circuit for circulating the cooling water without passing through the engine.
  • a solenoid valve is disposed in the cooling control system.
  • the solenoid valve is adapted not to completely block a flow of the cooling water circulating within the circuit passing through the engine, even if it is closed to block the circuit passing through the engine.
  • the cooling control system of the present invention is applied to a hybrid vehicle in which a prime mover is comprised of an internal combustion engine and a plurality of electric motors.
  • a drive mode can be selected from a hybrid mode where the vehicle is powered by both of the engine and the motor, a motor mode where the vehicle is powered by the motor(s) while stopping the engine and so on depending on a vehicle speed.
  • the engine may be driven when launching the vehicle, and stopped when stopping the vehicle.
  • the engine is selectively operated depending on the selected drive mode and the running condition of the vehicle.
  • a gasoline engine, a diesel engine, a natural gas engine may be used as the engine 1 of the invention, and a rotational speed and an output torque of the engine 1 can be controlled electrically.
  • a conventional AC motor serves as a motor and a generator may be used as the electric motor.
  • FIG. 12 shows a preferred example of the cooling control system of the present invention.
  • a not shown water jacket is attached to a cylinder block and a cylinder head.
  • the cooling control system is provided with an electric water pump 2 for supplying the cooling water to the water jacket.
  • the water pump 2 is comprised of a motor and an impeller rotated by the motor to deliver the cooling water.
  • a discharging amount and a discharging pressure of the water pump 2 can be altered by electrically changing a rotational speed of the motor.
  • the water pump 2 is comprised of a PWM (Pulse Width Modulation) circuit for controlling a motor speed of the water pump 2 by a PWM method in response to a command signal from a below-mentioned electronic control unit.
  • PWM Pulse Width Modulation
  • a rotational speed of the motor is raised by increasing a duty cycle thereof, and lowered by decreasing the duty cycle thereof.
  • a discharging port of the water pump 2 is connected with the water jacket of the engine 1 through a feeding conduit 3 , and a suction port of the water pump 2 is connected with the water jacket of the engine 1 through a return conduit 4 .
  • a first temperature sensor is arranged in the vicinity of a connection between the water jacket and the return conduit 4 .
  • the return conduit 4 is also connected to a radiator 6 .
  • the radiator 6 is adapted to exchange heat between the cooling water warmed as a result of drawing heat from the engine 1 and the external air thereby cooling the cooling water.
  • the cooling water thus cooled by the radiator 6 is delivered to the suction port of the water pump 2 through a conventional thermostat 7 .
  • the thermostat 7 is adapted to allow the cooling water to flow toward the radiator 6 if the temperature of the cooling water is higher than a predetermined temperature, and to inhibit the cooling water to flow toward the radiator 6 if the temperature of the cooling water is lower than a predetermined temperature.
  • the predetermined temperature is set to a value that can determine whether or not warm-up of the engine 1 has been completed. In the following explanation, the predetermined temperature thus determined will be called the “warm-up temperature”.
  • the thermostat 7 always allows the cooling water to flow from a below-mentioned bypass conduit 8 toward the return conduit 4 .
  • the bypass conduit 8 connects the feeding conduit 3 to the return conduit 4 , and a second temperature sensor 9 is disposed on the bypass conduit 8 .
  • a branch conduit 10 branches out from the return conduit 4 between the engine 1 and the radiator 6 to be connected to the bypass conduit 8 , and a solenoid valve 11 is disposed on the branch conduit 10 to alter a flow rate of the cooling water supplied to the water jacket by selectively opening and closing the branch conduit 10 .
  • the solenoid valve 11 is closed when energized so that the flow rate of the cooling water flowing toward the water jacket is reduced. By contrast, the solenoid valve 11 is opened when unenergized so that the flow rate of the cooling water flowing toward the water jacket is increased.
  • the solenoid valve 11 is provided with a water passage indicated by a broken line in FIG. 12 for allowing the cooling water to flow through the branch conduit 10 when the solenoid valve 11 is closed.
  • the water passage may be formed by forming a through hole or a notch penetrating through a valve element that selectively opens and closes input and output ports of the solenoid valve 11 .
  • an additional pipe may be arranged to connect an upstream side and a downstream side of the solenoid valve 11 to serve as the water passage.
  • a cross-section of the water passage is smaller than that of the branch conduit 10 .
  • the solenoid valve 11 is connected to an auxiliary battery.
  • the auxiliary battery is also connected to a main battery through a DC-DC converter to provide power to auxiliaries such as an air conditioner and a headlight.
  • the hydraulic control unknit is provided with an electronic control unit 12 serving as the controller of the present invention.
  • the electronic control unit 12 will be abbreviated as the “ECU” 12 for the sake of convenience.
  • the ECU 12 is comprised mainly of a microcomputer configured to carry out a calculation on the basis of input data and preinstalled data, and calculation results are sent to the solenoid valve 11 and the water pump 2 in the form of command signals. For example, signals from the temperature sensors 5 and 9 , an engine speed sensor, a vehicle speed sensor, an igniter and so on are sent to the ECU 12 .
  • the temperature of the cooling water is lower than the warm-up temperature but higher than another reference temperature that is slightly lower than the warm-up temperature, the temperature of the cooling water has not yet been raised sufficiently.
  • another reference temperature will be called the “pre-warm-up temperature”.
  • the cooling water is prevented from flowing toward the radiator 6 by the thermostat 7 but the solenoid valve 11 is unenergized to be opened to raise the temperature of the cooling water in the water jacket in a mild manner.
  • the cooling water partially flows through the feeding conduit 3 , the water jacket, the branch conduit 10 and the return conduit 4 , and remaining cooling water flows through the feeding conduit 3 , the bypass conduit 8 and the return conduit 4 .
  • the cooling water flowing through the water jacket is mixed with the cooling water flowing through the bypass conduit 8 at the bypass conduit 8 and the return conduit 4 .
  • the temperature of the cooling water in the water jacket is raised mildly in comparison with a case in which the solenoid valve 11 is closed.
  • the cooling water is allowed by the thermostat 7 to flow toward the radiator 6 .
  • the solenoid valve 11 is opened so that the cooling water is partially delivered to the radiator 6 to be cooled. That is, a mixture of the cooling water thus cooled by the radiator 6 and the cooling water circulating within another circuit is discharged from the water pump 2 to circulate within each circuit. For this reason, the temperature of the cooling water in the water jacket will not be raised excessively. Accordingly, the circuit passing through the water jacket serves as the cooling circuit of the invention, and the circuit passing through the bypass conduit 8 serves as the bypass circuit of the invention.
  • the cooling control system of the present invention is configured to estimate an amount of clogging of the water passage for delivering the cooling water to the water jacket in case the solenoid valve 11 is closed.
  • an amount of clogging can be represented by a reduction percentage (%) of a cross-sectional area of the water passage that is clogged by foreign material such as water stain and dust. Specifically, if the amount of clogging is 15%, this means that 15% of the cross-sectional area of the water passage is closed by the foreign material.
  • FIG. 1 there is shown a flowchart explaining the first control example of the cooling control system for the engine. The routine shown in FIG. 1 is repeated at predetermined interval.
  • a temperature Thw of the cooling water flowing out of the water jacket of the engine 1 is detected by the first temperature sensor 5 .
  • a temperature Thb of the cooling water flowing through the bypass conduit 8 is detected by the second temperature sensor 9 .
  • a temperature difference ⁇ Tini is calculated by subtracting the temperature Thb of the cooling water flowing through the bypass conduit 8 from the temperature Thw of the cooling water flowing out of the engine 1 .
  • the temperature difference ⁇ Tini thus calculated will be called the “initial temperature difference” ⁇ Tini in the following description.
  • the reference value Tdet is a temperature difference determined based on a result of experimentation or simulation that is possible to determine an amount of clogging of the water passage within a predetermined period of time.
  • the reference value Tdet is set to 20 degrees C.
  • an engine stop can be determined based on a current running condition of the vehicle, a current driving mode, a current vehicle speed and so on. If the initial temperature difference ⁇ Tini is smaller than the reference value Tdet, or if the engine 1 is under operation so that the answer of step S 1 is NO, the routine is returned without carrying out any specific control.
  • the initial temperature difference ⁇ Tini is saved to be used at after-mentioned step S 4 .
  • the water pump 2 is activated and the solenoid valve 11 is closed (at step S 2 ). Specifically, the solenoid valve 11 is closed to block the bypass conduit 10 . In this case, however, the cooling water is still allowed to flow through the water passage of the solenoid valve 11 . In this situation, the drive duty cycle of the water pump 2 may be adjusted arbitrarily depending on the running condition of the vehicle.
  • a preset time t 1 has elapsed (at step S 3 ).
  • a flow rate of the cooling water flowing therethrough is reduced. This means that a heat transfer via the cooling water is reduced. Consequently, a difference between the detection values of the temperature sensors 5 and 9 is widened.
  • the flow rate of the cooling water flowing therethrough is comparatively larger than that of the case in which the water passage is clogged heavily. That is, a heat transfer via the cooling water is comparatively large so that the difference between the detection values of the temperature sensors 5 and 9 is decreased.
  • FIG. 2 shows an example of a map determining the waiting time with respect to the drive duty cycle of the water pump 2 .
  • the waiting time is set to a short period of time.
  • the waiting time is set to a long period of time.
  • step S 3 is repeated until the preset time t 1 has elapsed.
  • the preset time t 1 has elapsed so that the answer of step S 3 is YES
  • the temperature Thw (now) of the cooling water flowing out of the engine 1 is detected again by the first temperature sensor 5
  • the temperature Thb (now) of the cooling water flowing through the bypass conduit 8 is detected again by the second temperature sensor 9 .
  • a temperature difference ⁇ Tnow is calculated by subtracting the temperature Thb (now) of the cooling water flowing through the bypass conduit 8 from the temperature Thw (now) of the cooling water flowing out of the engine 1 (at step S 4 ).
  • an estimated value of an amount of clogging of the water passage is calculated (at step S 5 ).
  • the estimated value of an amount of clogging is calculated by the following procedures. Referring now to FIG. 3 , there is shown a graph indicating a relation between the initial temperature difference ⁇ Tini and the current temperature difference ⁇ Tnow. As can be seen from FIG. 3 , in case the water passage is not clogged with foreign matter or an amount of clogging is small, the cooling water is allowed to flow through the water jacket smoothly so that the current temperature difference ⁇ Tnow is small. By contrast, in case the water passage is completely clogged with the foreign matter or the amount of clogging is large, the cooling water remains in the water jacket.
  • the vertical axis represents a difference ⁇ Td 1 between the initial temperature difference ⁇ Tini and the current temperature difference ⁇ Tnow.
  • the difference ⁇ Td 1 is large in case the amount of clogging of the water passage is small, and the difference ⁇ Td 1 is small in case the amount of clogging of the water passage is large. This means that the amount of clogging is large if the difference ⁇ Td 1 between ⁇ Tini and ⁇ Tnow is small. Accordingly, the amount of clogging of the water passage can be estimated with reference to a map shown in FIG. 4 that determines a relation between the clogging amount and the difference ⁇ Td 1 .
  • the threshold value PV 1 is set to 15%. If the amount of clogging of the water passage estimated at step S 5 is smaller than the threshold value PV 1 so that the answer of step S 6 is NO, the routine is returned without carrying out any specific control. By contrast, if the amount of clogging of the water passage estimated at step S 5 is larger than the threshold value PV 1 so that the answer of step S 6 is YES, the solenoid valve 11 is opened (at step S 7 ). Consequently, the cooling water flowing out of the water jacket is allowed to flow through the branch conduit 10 . Accordingly, the threshold value PV 1 corresponds to the first threshold value of the present invention.
  • the cooling control system of the present invention is configured to estimate an amount of clogging of the water passage, and to open the solenoid valve 11 if the estimated value of the clogging amount is larger than the threshold value PV 1 . According to the present invention, therefore, the cooling water is allowed to circulate through the water jacket even if the water passage is clogged with foreign material.
  • step S 1 if the answer of step S 1 is YES, it is determined whether or not an external temperature measured by a not shown sensor is lower than a predetermined threshold value (at step S 8 ). Given that the external temperature is low, a temperature of the cooling water is lowered naturally and an accuracy of the above-explained estimation of clogging amount based on the temperature difference may be deteriorated.
  • the threshold value for the external temperature is set to a value sufficiently lower than the above-mentioned warm-up temperature. If the external temperature is higher than the threshold value so that the answer of step S 8 is NO, the routine advances to step S 1 of FIG. 1 to carry out the control shown in FIG. 1 .
  • step S 9 the routine advances sequentially to steps S 2 and S 9 to stop the water pump 2 (at step S 9 ). Then, it is determined whether or not a preset time t 2 has elapsed from a point at which the water pump 2 was stopped (at step S 10 ). As the preset time t 1 used at step S 3 shown in FIG. 1 , the preset time t 2 is the waiting time until the temperature of the cooling water flowing through the water passage starts changing. The determination of step S 10 is also repeated until the preset time t 2 has elapsed.
  • a lowered amount ⁇ Tcold of the temperature of the cooling water lowered by the external temperature is calculated (at step S 11 ).
  • a temperature Thw (c) of the cooling water flowing out of the engine 1 and a temperature Thb (c) of the cooling water flowing through the bypass conduit 8 are detected when the preset time t 2 has elapsed.
  • the lowered amount ⁇ Tcold is calculated by subtracting a difference between the temperatures Thw (c) and Thb (c) from the initial temperature difference ⁇ Tini.
  • step S 12 the water pump 2 is activated (at step S 12 ). Thereafter, the routine advances to above-explained step S 3 to determine whether or not the preset time t 1 has elapsed. If the preset time t 1 has elapsed so that the answer of step S 3 is YES, the routine advances to above-explained step S 4 .
  • step S 4 specifically, the current temperatures Thw (now) of the cooling water flowing out of the engine 1 and Thb (now) of the cooling water flowing through the bypass conduit 8 under the condition where the water pump 2 is activated are detected by the temperature sensors 5 and 9 . As described, at step S 4 , a current temperature difference ⁇ Tnow is calculated by subtracting the temperature Thb (now) from the temperature Thw (now).
  • an estimated value of an amount of clogging of the water passage is calculated while eliminating an influence of the external temperature such as the lowered amount ⁇ Tcold (at step S 13 ).
  • the difference ⁇ Td 1 between the initial temperature difference ⁇ Tini and the current temperature difference ⁇ Tnow is calculated.
  • the difference ⁇ Td 1 thus calculated is affected by the external temperature. Therefore, a difference ⁇ Td 2 from which an influence of the external temperature is eliminated is calculated as expressed by the following expression:
  • ⁇ Td 2 ( ⁇ Tini ⁇ T now) ⁇ ( t 1+ t 2) ⁇ T cold.
  • the amount of clogging is large if the difference ⁇ Td 2 is large.
  • the amount of clogging of the water passage can be estimated with reference to a map shown in FIG. 6 that determines a relation between the clogging amount and the difference ⁇ Td 2 . Then, the routine advances to step S 6 shown in FIG. 1 .
  • the estimated value of an amount of clogging of the water passage can be calculated while eliminating an influence of the external temperature so that the accuracy of estimating the amount of clogging can be improved. That is, the cooling control system will not erroneously estimate a fact that the clogging amount of the water passage is small or zero if the water passage is clogged with the foreign material.
  • FIG. 7 there is shown a flowchart explaining the third control example of the cooling control system configured to accurately estimate an amount of clogging of the water passage in case the amount of clogging during previous trip is larger than the threshold value PV 1 . That is, the example shown in FIG. 7 is configured to estimate the clogging amount of the water passage without determining a clogging of the water passage erroneously under a situation where the water passage is not clogged with foreign material.
  • common numbers are allotted to the steps identical to those in FIG. 1 .
  • step S 14 it is determined whether or not an estimated value of an amount of clogging of the water passage calculated during the previous trip is smaller than the threshold value PV 1 (at step S 14 ). If the estimated value of an amount of clogging calculated during the previous trip is smaller than the threshold value PV 1 so that the answer of step S 14 is YES, the drive duty cycle of the water pump 2 for the current trip is set to be less than that for the previous trip (at step S 15 ). If the estimated value of an amount of clogging calculated during the previous trip is smaller than the threshold value PV 1 , the control system estimates a fact that the amount of clogging is smaller than the threshold value PV 1 also during the current trip.
  • step S 14 the drive duty cycle of the water pump 2 is set to the maximum value (at step S 16 ). Consequently, the discharging amount of the water pump 2 can be increased to increase the flow rate of the cooling water flowing through the water jacket without opening the solenoid valve 11 .
  • step S 17 the routine advances to step S 3 to determine whether or not the preset time t 1 has elapsed.
  • An amount of clogging during the current trip is estimated at step S 5 , and then, it is determined whether or not the estimated value of the amount of clogging of the water passage during the current trip is larger than another threshold value PV 2 (at step S 18 ).
  • the threshold value PV 2 is set to a value larger than the threshold value PV 1 , for example, set to 60%. If the estimated value of an amount of clogging during the current trip is larger than the threshold value PV 2 , the control system determines a fact that the water passage is clogged abnormally with foreign material. In this case, the solenoid valve 11 is opened (at step S 19 ).
  • step S 20 it is determined whether or not the estimated value of an amount of clogging is larger than the threshold value PV 1 (at step S 20 ). If the estimated value of an amount of clogging of the water passage is smaller than the threshold value PV 1 so that the answer of step S 20 is NO, the control system determines a fact that the water passage is in a normal condition without being clogged with foreign material (at step S 21 ). By contrast, if the estimated value of an amount of clogging of the water passage is larger than the threshold value PV 1 so that the answer of step S 20 is YES, the routine advances to step S 22 .
  • the estimated value of an amount of clogging of the water passage is larger than the threshold value PV 1 but smaller than the threshold value PV 2 . Consequently, the control system makes a determination of a quasi-clogging of the water passage.
  • a drive duty cycle of the water pump 2 may be calculated in a manner such that the accuracy for estimating an amount of clogging for the next trip will be improved in comparison with that during the current trip. In this case, the amount of clogging will be estimated based on the drive duty cycle of the water pump 2 calculated at step S 22 .
  • the amount of clogging during the current trip is estimated while increasing the drive duty cycle of the water pump 2 .
  • the cooling water is allowed to flow through the water jacket smoother than the case in which the drive duty cycle of the water pump 2 is small so that the accuracy for estimating the amount of clogging can be improved in comparison with that during the previous trip.
  • FIG. 8 there is shown a flowchart explaining the fourth control example of the cooling control system configured to alter the drive duty cycle of the water pump 2 depending on the vehicle speed to estimate an amount of clogging of the water passage.
  • the control example shown in FIG. 8 may be applied to a hybrid vehicle in which a prime mover is comprised of an engine and a motor.
  • common numbers are allotted to the steps identical to those in FIG. 1 .
  • the initial temperature difference ⁇ Tini is saved and the drive duty cycle of the water pump 2 is adjusted according to the vehicle speed (at step S 23 ).
  • the drive duty cycle of the water pump 2 may be determined with reference to a preinstalled map shown in FIG. 9 . Given that the vehicle speed is higher than a predetermined speed, the engine 1 will be operated frequently and heated significantly. In this case, therefore, the drive duty cycle of the water pump 2 is increased to the maximum value. To this end, the vehicle speed can be detected by a not shown speed sensor. Then, the routine advances to step S 3 .
  • the vehicle is powered by the motor more frequently rather than powered by the engine.
  • the drive duty cycle of the water pump 2 can be reduced in comparison with the case in which the vehicle runs at a high speed so that the amount of clogging of the water passage can be estimated more accurately without operating the engine 1 .
  • a flow rate of the cooling water can be reduced so that the engine 1 can be prevented from being cooled excessively.
  • the hybrid vehicle runs at a high speed, the vehicle is powered by the engine more frequently rather than powered by the motor. In this case, therefore, an amount of clogging of the water passage can be estimated promptly while stopping the engine 1 by increasing the drive duty cycle of the water pump 2 .
  • FIG. 10 there is shown a flowchart explaining the fifth control example of the cooling control system configured to alter a flow rate of the cooling water flowing through the water jacket while closing the solenoid valve 11 depending on an estimated value of clogging of the water passage.
  • common numbers are allotted to the steps identical to those in FIG. 1 .
  • step S 5 it is determined whether or not an estimated value of an amount of clogging is larger than a still another threshold value PV 3 (at step S 24 ).
  • the threshold value PV 3 is set to 50% that is larger than the threshold value PV 1 but smaller than the threshold value PV 2 . If the estimated value of the amount of clogging is larger than the threshold value PV 3 so that the answer of step S 24 is YES, the solenoid valve 11 is opened (at step S 25 ). That is, if the estimated value of an amount of clogging is large, the cooling water flowing out of the water jacket is allowed to circulate through the branch conduit 10 .
  • step S 26 it is determined whether or not the estimated value of the amount of clogging is larger than the threshold value PV 1 (at step S 26 ). If the estimated value of the amount of clogging is smaller than the threshold value PV 1 so that the answer of step S 26 is NO, the routine is returned.
  • a coefficient for correcting the drive duty cycle of the water pump 2 is calculated to alter the drive duty cycle in accordance with the estimated value of the amount of clogging (at step S 27 ).
  • the correction coefficient may be determined according to the estimated value of an amount of clogging with reference to a preinstalled map shown in FIG. 11 .
  • the drive duty cycle is corrected by the correction coefficient thus calculated (at step S 28 ).
  • the drive duty cycle of the water pump 2 is calculated by multiplying the current drive duty cycle by the correction coefficient, and the water pump 2 is driven in accordance with the drive duty cycle thus corrected.
  • the maximum value of the drive duty cycle to be corrected by the correction coefficient is limited to a value that can drive the water pump 2 without reducing fuel economy, on the basis of a result of experimentation or simulation.
  • the fuel economy will not be reduced even if the drive duty cycle of the water pump 2 is increased to increase a flow rate of the cooling water flowing through the water jacket.
  • the solenoid valve 11 is opened to avoid such reduction in the fuel economy.
  • the solenoid valve 11 will not be opened if the estimated value of the amount of clogging is smaller than the threshold value PV 3 so that the engine 1 can be prevented from being cooled overly.
  • the solenoid valve 11 is opened. In this case, therefore, the drive duty cycle of the water pump 2 does not have to be increased so that the fuel economy will not be reduced.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
US14/408,328 2012-06-18 2012-06-18 Cooling control system for engine Abandoned US20150240702A1 (en)

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US9874134B2 (en) * 2013-04-30 2018-01-23 Toyota Jidosha Kabushiki Kaisha Cooling water control apparatus
JP6079759B2 (ja) * 2014-12-01 2017-02-15 トヨタ自動車株式会社 エンジン冷却システムの孔詰まり判定装置及び方法
JP6079764B2 (ja) * 2014-12-10 2017-02-15 トヨタ自動車株式会社 内燃機関の冷却システムおよびその制御方法
JP6079766B2 (ja) * 2014-12-12 2017-02-15 トヨタ自動車株式会社 エンジン冷却システム及びその運転方法
JP6241435B2 (ja) * 2015-03-03 2017-12-06 トヨタ自動車株式会社 内燃機関の温度制御装置
JP6374342B2 (ja) * 2015-04-08 2018-08-15 トヨタ自動車株式会社 エンジンの冷却装置
JP6265195B2 (ja) * 2015-10-01 2018-01-24 トヨタ自動車株式会社 内燃機関の制御装置
CN106089395B (zh) 2016-07-26 2018-11-02 广州汽车集团股份有限公司 发动机水温控制方法及装置
JP6627826B2 (ja) * 2017-07-10 2020-01-08 トヨタ自動車株式会社 熱交換システムの制御装置
JP6610622B2 (ja) * 2017-07-10 2019-11-27 トヨタ自動車株式会社 熱交換システムの制御装置
JP7076396B2 (ja) * 2019-03-27 2022-05-27 日立建機株式会社 作業機械
CN113109390B (zh) * 2021-05-17 2023-09-12 西安热工研究院有限公司 一种汽轮发电机定子冷却水化学清洗效果评价方法
CN115514242B (zh) * 2021-06-22 2025-07-29 富士电机株式会社 电力转换装置、信息处理装置以及信息处理方法

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CN104379894A (zh) 2015-02-25
JP5910743B2 (ja) 2016-04-27
WO2013190619A1 (ja) 2013-12-27
EP2863030A1 (en) 2015-04-22
EP2863030A4 (en) 2016-02-24

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