JP2009197616A - Cooling system, cooling control device, and flow rate control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling system capable of accurately controlling the water temperature of cooling water. <P>SOLUTION: This cooling system has a cooling water path B provided with a radiator 4 for cooling the cooling water on a circulation route, in which the cooling water circulates to an engine 1, a cooling water path A bypassing the radiator 4 on the circulation route, a first electric WP 10 for adjusting the flow rate of the cooling water flowing in the cooling water path B, a second electric WP 11 for adjusting the flow rate of the cooling water flowing into the engine 1, and an ECU 20 for adjusting the flow rate of a fluid flowing in the cooling water path A and the cooling water path B by controlling the drive amount of the first electric WP 10 and the second electric WP 11. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an engine cooling structure using an electric water pump.

  The electric water pump is driven by electric power supplied from the battery, and can be controlled without depending on the engine speed. Therefore, the optimum flow rate control based on the request from the cooling target is possible, and the use as the core of the cooling structure in the hybrid system where the engine is not necessarily rotating is expected.

  FIG. 1 shows a schematic configuration of a vehicle cooling system using an electric water pump. In this system, a radiator 4, a thermostat 5, and an electric water pump 6 (hereinafter also abbreviated as electric WP) are provided on a cooling water circulation path for cooling the engine 1. A water temperature sensor 2 for measuring the temperature of the cooling water is provided near the cooling water outlet of the engine 1.

  The cooling water discharged from the engine 1 and passing through the heat management target equipment 3 such as a heater core of an air conditioner or an exhaust heat recovery device branches into a cooling water channel A and a cooling water channel B at a branch point X shown in FIG. The arrows shown in FIG. 1 indicate the direction in which the cooling water flows. No special device is provided in the cooling water channel A, and the radiator 4 and the thermostat 5 are provided in the cooling water channel B. The cooling water that has passed through the cooling water channel A or the cooling water channel B merges at the junction Y and is re-supplied to the engine 1 by the electric WP 6.

  The radiator 4 is a device that cools the cooling water. The thermostat 5 is a bubble that automatically opens and closes depending on the temperature of the cooling water in order to keep the temperature of the cooling water at 80 ° C. to 90 ° C. When the temperature of the cooling water is low, the thermostat 5 is closed and the electric WP 6 is closed. The cooling water does not circulate to the radiator 4 even if the motor rotates. That is, the cooling water does not flow through the cooling water channel B but flows through the cooling water channel A. When the temperature of the cooling water increases (according to the temperature rise of the cooling water), the thermostat 5 is opened by the heat of the cooling water, and the cooling water circulates to the radiator 4.

  In Patent Document 1, in order to increase the circulation flow rate of the cooling water to the heat exchanger and improve the cooling capacity of the heat exchanger, the second conduit for introducing the cooling water cooled by the heat exchanger into the internal combustion engine is disclosed. A main pump provided in the middle, a first water conduit for leading cooling water flowing out from the internal combustion engine to the heat exchanger, a sub pump provided in a bypass water passage connecting the second water conduit, and an internal combustion engine A control unit is provided that detects the cooling water temperature near the cooling water outlet and controls the operation of the sub-pump.

Japanese Patent No. 2707792

In the vehicle cooling system using the electric WP 6 shown in FIG. 1, the cooling water temperature can be controlled to some extent by driving the electric WP 6 according to the cooling water temperature. However, the cooling water channel A and the radiator 4 are arranged. The ratio of the cooling water flowing into the cooling water channel B depends on the characteristics of the thermostat 5.
For this reason, it is not possible to perform highly accurate control such as stirring the cooling water through only the cooling water channel A without passing through the radiator 4.

  The technology disclosed in Patent Document 1 also uses two pumps, a main pump and a sub pump. However, the sub pump is used only to increase the circulation flow rate of cooling water to the heat exchanger and improve the cooling capacity of the heat exchanger. I am using it.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cooling system, a cooling control device, and a flow rate control method capable of accurately controlling the coolant temperature.

In order to achieve this object, a cooling system of the present invention is provided on a circulation path for circulating a fluid in an engine, the first path provided with cooling means for cooling the fluid, and the circulation path. A second passage that bypasses the cooling means, a first pump that adjusts the flow rate of the fluid that flows through the first passage, a second pump that adjusts the flow rate of the fluid that flows into the engine, and the first pump, The driving amount of the second pump is controlled to control the first passage and the control means for adjusting the flow rate of the fluid flowing through the second passage.
According to the present invention, the flow rate of the cooling water flowing through the first passage and the second passage can be adjusted by adjusting the drive amounts of the first pump and the second pump, so that the coolant temperature control is accurate. Can be done well.

The cooling control device of the present invention includes a first pump for adjusting a flow rate of a fluid flowing through a first passage provided with a cooling means for cooling an engine fluid, and a second passage that bypasses the first passage or the cooling means. A cooling control device for controlling a second pump for adjusting a flow rate of the fluid flowing into the engine, wherein the driving amount of the first pump is larger than the driving amount of the second pump, and the cooling Control means for controlling the flow rate of the fluid cooled by the means to be larger than the flow rate of the fluid flowing into the engine is provided.
According to the present invention, by increasing the flow rate of the fluid cooled by the cooling means more than the flow rate of the fluid flowing into the engine, the fluid can be efficiently cooled and the engine can be quickly cooled.

The cooling control device of the present invention includes a first pump for adjusting a flow rate of a fluid flowing through a first passage provided with a cooling means for cooling an engine fluid, and a second passage that bypasses the first passage or the cooling means. A cooling control device that controls a second pump that adjusts the flow rate of the fluid flowing into the engine and restricts the flow rate of the fluid that flows through the first passage by stopping or weakly driving the first pump It has the control means to do.
According to the present invention, the flow rate of the fluid flowing through the cooling means can be limited, and the warm-up operation can be performed efficiently.

The cooling control device of the present invention includes a first pump for adjusting a flow rate of a fluid flowing through a first passage provided with a cooling means for cooling an engine fluid, and a second passage that bypasses the first passage or the cooling means. A cooling control device for controlling a second pump for adjusting a flow rate of the fluid flowing into the engine, wherein the first pump and the second pump are adjusted in accordance with a start timing of an exhaust process of the engine. It has a control means for driving.
According to the present invention, the fluid heated in the exhaust process can be carried to the cooling means and efficiently cooled.

The control means may be configured to calculate the driving amount of the first pump based on at least one of the engine speed, the suction load factor, the air-fuel ratio, and the fluid temperature.
Therefore, the first pump can be driven with an optimal driving amount corresponding to the amount of heat exhausted from the engine, and the fluid can be cooled.

The cooling control device of the present invention includes a first pump for adjusting a flow rate of a fluid flowing through a first passage provided with a cooling means for cooling an engine fluid, and a second passage that bypasses the first passage or the cooling means. A cooling control device for controlling a second pump for adjusting a flow rate of the fluid flowing into the engine, wherein the first pump is fully closed and the second pump is driven for a predetermined time. The abnormality is determined based on at least one of a temperature at which the temperature of the fluid converges, an elapsed time from the start of the temperature change of the fluid to the convergence, and an elapsed time until the cooling temperature of the cooling water changes. It has the control means to perform.
Therefore, the occurrence of abnormality can be detected effectively.

  In the flow rate control method of the present invention, the flow rate for controlling the flow rate between the first passage provided with the cooling means for cooling the fluid and the second passage bypassing the cooling means on the circulation path for circulating the fluid in the engine. A control method comprising: a first pump for adjusting a flow rate of a fluid flowing through the first passage; and a second pump for adjusting a flow rate of causing the fluid flowing through the first passage or the second passage to flow into the engine. By controlling the driving amount, the flow rate of the first passage and the second passage is controlled.

  According to the present invention, it is possible to accurately control the coolant temperature.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

First, the configuration of the present embodiment will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the apparatus same as the conventional system shown in FIG. 1, and detailed description is abbreviate | omitted.
The vehicle cooling system of the present embodiment shown in FIG. 2 includes a radiator 4, a first electric water pump (hereinafter also abbreviated as a first electric WP) 10 on a cooling water circulation path for cooling the engine 1, Two electric water pumps (hereinafter also abbreviated as second electric WP) 11 are provided. The first electric WP 10 and the second electric WP 11 are electric WPs having similar functions and operate according to the control of the ECU 20.

  Also in this embodiment, a branch point X is provided on the circulation path for circulating the cooling water to the engine 1, and the cooling water is branched into the cooling water path A and the cooling water path B at the branch point X. A special device is not provided on the cooling water channel A, and the radiator 4 and the first electric WP 10 are provided on the cooling water channel B. The cooling water that has passed through the cooling water passage A or the cooling water passage B joins at the junction Y, and is resupplied to the engine 1 by the second electric WP11.

  FIG. 3 shows a configuration of the ECU 20 that drives and controls the first electric WP 10 and the second electric WP 11. As shown in FIG. 3, the ECU 20 includes an input interface circuit 21, a CPU (Central Processing Unit) 22, a ROM (Read Only Memory) 23, a RAM (Random Access Memory) 24, an EEPROM (Electronically Erasable and Programmable Read Only Memory) 25, An output interface circuit 26 and the like are included.

Sensor signals measured by sensors such as the water temperature sensor 2, the crank angle sensor 50, the air-fuel ratio (hereinafter abbreviated as A / F) sensor 51, and the air flow meter 52 are input to the input interface circuit 21.
The output interface circuit 26 outputs a control signal from the CPU 22 to the first electric WP 10, the second electric WP 11, the injector 12, the spark plug 13, and the like.
The water temperature sensor 2 measures the temperature of the cooling water flowing in the cylinder block of the engine 1 and outputs a sensor signal indicating the measured value to the ECU 20.
The crank angle sensor 50 outputs a signal representing the rotation speed of the crankshaft (engine speed) and the rotation angle of the crankshaft to the ECU 20.
The A / F sensor 51 is an exhaust gas sensor provided in the exhaust passage, and detects the air-fuel ratio based on the oxygen concentration in the exhaust gas. A sensor signal representing the detected air-fuel ratio is output to the ECU 20.
The air flow meter 52 is a sensor that detects the amount of intake air flowing through an intake passage (not shown) of the engine 1. A sensor signal indicating the detected intake air amount is output to the ECU 20.
The input interface circuit 21 inputs sensor signals output from these sensors and outputs them to the CPU 22.

The CPU 22 reads a program recorded in the ROM 23 and performs calculations according to this program. The processing procedure of the CPU 22 will be described later with reference to a flowchart. Data of the calculation result is written in the RAM 24, and data that has been written in the RAM 24 and needs to be saved when the power is turned off is written in the EEPEOM 25.
The CPU 22 inputs sensor signals from the sensors, and calculates the driving amounts of the first electric WP 10 and the second electric WP 11 based on these sensor signals. Based on the calculated drive amount, a control signal for controlling the first electric WP 10 and the second electric WP 11 is output.
Further, the CPU 22 determines the engine ignition timing and the fuel injection amount based on the sensor signal. Based on the determined information, a control signal for controlling the injector 12 and the spark plug 13 is output.

In this embodiment, as shown in FIG. 2, a first electric WP 10 for controlling the flow rate of the cooling water passage B provided with the radiator 4 is provided instead of the thermostat 5.
A flow path from the junction B to the engine 1 through the second electric WP 11 is referred to as a cooling water path C, and the flow rates of the cooling water flowing through the cooling water paths A, B, and C are set as Qa, Qb, and Qc, respectively.
The flow rate of the cooling water flowing through the cooling water channels A, B, and C requires a pressure correction value and the like, but has a relation of the following expression (1).
Qa + Qb = Qc (1)

  Since the flow rate Qb of the cooling water channel B can be controlled by the first electric WP10 and the flow rate Qc of the cooling water channel C can be controlled by the second electric WP11, the flow rate of the cooling water flowing through the cooling water channel A by these two electric WPs Qa can also be controlled.

Here, the cooling efficiency by the radiator 4 is set to E, and E is defined as the following formula (2).
E = Qb / Qc (2)
By controlling the first electric WP 10 and the second electric WP 11 by the ECU 20 and controlling the cooling efficiency E to be equivalent to that of the thermostat 5 shown in FIG. 1, control equivalent to that using the thermostat 5 can be realized.

Further, the ECU 20 controls the first electric WP 10 and the second electric WP 11 and corrects E as necessary, whereby the following warm-up control and cooling control can be accurately performed.
[Re-exhaust heat control]
When the first electric WP10 is driven stronger than the second electric WP11 and E> 1, the following behavior is exhibited.
Since E = Qb / Qc> 1, Qb> Qc, and thus Qa = Qc−Qb <0
This state is shown in FIG. Since Qa is negative, the cooling water channel A indicates that the cooling water is flowing backward as shown in FIG. The cooling water that has flowed back through the cooling water channel A merges with the cooling water toward the radiator 4, and is cooled again by the radiator 4. Therefore, the cooling water can be efficiently cooled and the engine 1 can be effectively cooled.

  For example, this re-exhaust heat control is more effective when the coolant temperature measured by the water temperature sensor 2 is 100 ° C. or higher, or in a high rotation region where the engine speed is 6000 rpm or higher.

[Optimum cooling efficiency control]
At the time of warm-up operation such as when the engine is started, it is necessary to efficiently warm up the engine 1 so that heat from the engine 1 quickly penetrates the entire cooling water.
Therefore, in this optimal optimum cooling efficiency control, the second electric WP11 is driven strongly and the first electric WP10 is driven weakly or stopped. The flow rate of the cooling water flowing through the cooling water channel B can be suppressed, and the cooling water can be circulated through the cooling water channel C, the engine 1, and the cooling water channel A. The first electric WP 10 may be set so as not to be driven from the beginning, or the driving force may be decreased stepwise.
In the conventional configuration using the thermostat 5 shown in FIG. 1, the flow rate of the cooling water channel B increases and the warm-up efficiency decreases as the water temperature rises, but the twin configuration of the second electric WP11 and the first electric WP10 is adopted. Thus, the first electric WP is kept in a weakly driven or stopped state until the warm-up is completed, and the flow rate of the cooling water flowing through the cooling water channel B can be limited. Therefore, warm-up can be performed efficiently at high speed.

The processing procedure of the ECU 20 in this control will be described with reference to the flowchart shown in FIG.
When the ECU 20 starts the warm-up control by turning on the ignition key or the like (step S1 / YES), the ECU 20 first measures the coolant temperature from the water temperature sensor 2. If the coolant temperature measured by the water temperature sensor 2 is lower than the predetermined value (step S2 / NO), the first electric WP10 is set to a weak drive or stop (step S3), and the second electric WP11 is set to a strong drive. Set (step S4). As a result, the cooling water can be circulated through the cooling water channel C, the engine 1, and the cooling water channel A to efficiently warm up.
Further, when the coolant temperature measured by the coolant temperature sensor 2 is equal to or higher than a predetermined value (step S2 / YES), the ECU 20 determines that the warm-up control is completed, and the first electric WP10 and the second electric WP11 To normal control (step S5).

[Engine synchronous stirring control]
Due to the exhaust gas discharged from the engine 1 in the engine exhaust process, the temperature on the exhaust port side of the engine 1 rises. Since the heat of the exhaust gas is gradually transferred to the heat management target device 3, the temperature of the heat management target device 3 varies.
Therefore, in this embodiment, the second electric WP 11 is driven in synchronization with the exhaust process of the engine 1 to stir the entire cooling water channel, and the first electric WP 10 is also driven in synchronism with the exhaust process of the engine. Control to quickly cool the amount of heat generated in the exhaust process.
The amount of heat accumulated on the exhaust port side is carried to the branch point X side by driving the second electric WP11, and is conveyed to the radiator 4 by the driving of the first electric WP10 to be cooled. That is, the heat generated in a feedforward manner is cooled.

Here, the driving amount of the first electric WP 10 will be described.
Factors that determine the amount of heat exhausted from the engine 1 mainly include the following.
・ Engine speed (NE)
・ Inhalation load factor (KL)
・ Air-fuel ratio (A / F)
-Water temperature The intake load factor KL represents the ratio of the intake air amount in the operating state to the maximum intake air amount to the engine 1, and can be obtained from the intake air amount measured by the air flow meter 52.

From these factors, the drive amount (D) of the first electric WP 10 is determined using the following equation (3).
D = NE × KL × Ka × Kb (3)
Ka is an air-fuel ratio correction coefficient, and is obtained from the air-fuel ratio measured by the A / F sensor 51 with reference to the map shown in FIG.
Kb is a correction factor for the water temperature, and is obtained from the cooling water temperature measured by the water temperature sensor 2 with reference to the map shown in FIG.

A processing procedure of the ECU 20 in engine synchronous stirring control will be described with reference to a flowchart shown in FIG.
First, the ECU 20 calculates the intake load factor (KL) calculated based on the engine speed (NE) measured by the crank angle sensor 50, the intake air amount measured by the air flow meter 52, and the A / F sensor 51. From the air-fuel ratio correction coefficient Ka calculated based on the air-fuel ratio measured in step 5 and the water temperature correction coefficient Kb calculated based on the water temperature measured by the water temperature sensor 2, The drive amount D of 1 electric WP10 is calculated (step S11).

  Next, when the ECU 20 determines from the sensor information of the crank angle sensor 50 that it is time to shift the engine 1 to the exhaust process (step S12 / YES), the ECU 20 drives the first electric WP10 with the drive amount calculated in step S11. (Step S13). At the same time, the driving of the second electric WP11 is also started (step S14).

  When a predetermined time has elapsed from the driving of the first electric WP 10 and the second electric WP 11, the electric WP is returned to the normal control (step S 15). This control is performed in synchronization with the exhaust process of the engine.

[Abnormality detection control]
In the abnormality detection control, the first electric WP10 is fully closed, and the drive amount of the second electric WP11 is made constant to detect a system abnormality.
When the first electric WP 10 is fully closed and the second electric WP 11 is driven for a certain time to stir the cooling water in the water channel from the cooling water channel A to the cooling water channel C, the amount of heat generated in the engine 1 is evenly distributed in the cooling water channel. The cooling water temperature exhibits a characteristic behavior such as a first-order lag because it is accustomed.
Therefore, as shown in FIG. 8, the behavior of the ideal water temperature until the cooling water temperature converges to a constant value is modeled, and an abnormality is detected by comparing with the actual measurement result.
First, when the temperature at which the cooling water converges is higher than the modeled ideal temperature, it can be determined that the amount of cooling water is insufficient, and it can be determined that the water leak is abnormal.
The solid line shown in FIG. 8 shows the theoretical water temperature fluctuation, and the dotted line shows the actual water temperature fluctuation measured by the water temperature sensor 2. In the theoretical water temperature fluctuation, if the temperature at which the water temperature converges is β, the convergence temperature obtained by actual measurement is α, and K = β / α is greater than or equal to a predetermined value, it is determined that a water leakage abnormality has occurred. Can do.

  In addition, when the time constant T of the water temperature change is equal to or greater than a predetermined value, rust or the like is mixed into the cooling water and the cooling water is deteriorated to cause a specific heat abnormality or a driving abnormality of the second electric WP11 occurs. Can be determined. As shown in FIG. 8, the time constant T of the water temperature change represents the time when it is assumed that the final point (100%), that is, the convergence temperature β has been reached with the inclination at the time of rising (0%). Yes.

Further, when the start time D of the coolant temperature fluctuation is delayed from the predicted time, it can be determined that the flow resistance has increased due to rust mixing or the like, and it can be determined that the viscous resistance is abnormal.
When the time D (see FIG. 8) from when the first electric WP10 is closed and the second electric WP11 is started to when the coolant temperature starts to rise is later than the predicted time, the viscous resistance It can be determined as abnormal.

In the control described above. There is a possibility that a cooling characteristic different from the ideal may be exhibited due to aged deterioration of the cooling water or the electric WP.
At this time, when the control amount of the first electric WP10 and the second electric WP11 is provided with a correction learning value, the driving amount of the first electric WP10 is suppressed when it is too cool than the ideal value, and it is difficult to cool than the ideal In this case, the correction may be performed so as to increase the drive amount of the first electric WP10. The correction learning value may be learned in a situation where the cooling characteristics are more likely to appear, such as during rapid cooling or warm-up.

The preferred embodiments of the present invention have been described above. However, the scope of the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.
For example, in the above-described embodiments, the engine is taken as an example of the engine, but a motor mounted on a hybrid vehicle or an electric vehicle may be used as the engine.

It is a figure which shows the structure of the conventional cooling system. It is a figure which shows the structure of the cooling system concerning this invention. It is a figure which shows the structure of ECU. It is a figure which shows the flow of the cooling water at the time of reheat heat control. It is a flowchart which shows the process sequence of ECU at the time of optimal cooling efficiency control. (A) is a figure which shows the map which calculates A / F correction coefficient Ka from A / F value, (B) is a figure which shows the map which calculates water temperature correction coefficient Wb from water temperature. It is a flowchart which shows the process sequence of ECU at the time of engine synchronous stirring control. It is a figure for demonstrating the abnormality detection method at the time of abnormality detection control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Water temperature sensor 3 Heat management object apparatus 4 Radiator 10 1st electric WP
11 Second electric WP
12 Injector 13 Spark plug 20 ECU
50 Crank angle sensor 51 A / F sensor 52 Air flow meter

Claims (7)

A first passage provided on the circulation path for circulating the fluid to the engine and provided with a cooling means for cooling the fluid;
A second passage on the circulation path that bypasses the cooling means;
A first pump for adjusting a flow rate of the fluid flowing through the first passage;
A second pump for adjusting a flow rate of fluid flowing into the engine;
Control means for controlling the drive amount of the first pump and the second pump to adjust the flow rate of the fluid flowing through the first passage and the second passage;
A cooling system comprising: It flows into the engine through a first pump that adjusts the flow rate of the fluid flowing through the first passage provided with cooling means for cooling the engine fluid, and a second passage that bypasses the first passage or the cooling means. A cooling control device for controlling a second pump for adjusting a flow rate of fluid;
Control means for controlling the driving amount of the first pump to be larger than the driving amount of the second pump so that the flow rate of the fluid cooled by the cooling unit is larger than the flow rate of the fluid flowing into the engine. A cooling control device characterized by that. It flows into the engine through a first pump that adjusts the flow rate of the fluid flowing through the first passage provided with cooling means for cooling the engine fluid, and a second passage that bypasses the first passage or the cooling means. A cooling control device for controlling a second pump for adjusting a flow rate of fluid;
A cooling control apparatus comprising: a control unit that stops or weakly drives the first pump and restricts a flow rate of the fluid flowing through the first passage. It flows into the engine through a first pump that adjusts the flow rate of the fluid flowing through the first passage provided with cooling means for cooling the engine fluid, and a second passage that bypasses the first passage or the cooling means. A cooling control device for controlling a second pump for adjusting a flow rate of fluid;
A cooling control device comprising control means for driving the first pump and the second pump in accordance with the start timing of the exhaust process of the engine.   The said control means calculates the drive amount of a said 1st pump based on at least one of an engine speed, an intake load factor, an air fuel ratio, and fluid temperature. Cooling control device. It flows into the engine through a first pump that adjusts the flow rate of the fluid flowing through the first passage provided with cooling means for cooling the engine fluid, and a second passage that bypasses the first passage or the cooling means. A cooling control device for controlling a second pump for adjusting a flow rate of fluid;
The first pump is fully closed and the second pump is driven for a predetermined time, the temperature at which the fluid temperature converges, the elapsed time from the start of the temperature change of the fluid to the convergence, the cooling water A cooling control apparatus comprising: a control unit that performs abnormality determination based on at least one of an elapsed time until a change occurs in the cooling temperature. A flow rate control method for controlling a flow rate of a first passage provided with a cooling means for cooling the fluid and a second passage bypassing the cooling means on a circulation path for circulating the fluid in the engine,
The driving amount of the first pump for adjusting the flow rate of the fluid flowing through the first passage and the second pump for adjusting the flow rate of the fluid flowing through the first passage or the second passage into the engine are controlled. Thus, the flow rate control method characterized by controlling the flow rates of the first passage and the second passage.

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