JP2007100638A - Cooling water control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling water control device for an internal combustion engine capable of controlling cooling water temperature of an internal combustion engine to optimal water temperature. <P>SOLUTION: This cooling water control device for the internal combustion engine controls cooling water temperature of the internal combustion engine by using a valve opening adjusting means capable of electronically adjusting valve opening, is provided with cooling water optimal value estimation means S2, S3 estimating optimal value of cooling water temperature with using operation condition until present time of the internal combustion engine, and valve opening of the valve opening adjusting means is adjusted based on estimation value of cooling water temperature at an inlet of the internal combustion engine in future and the estimated optimal value of cooling water temperature (S8, S9, S10, S11, S12, S13). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cooling water control device for an internal combustion engine.

  Japanese Patent Application Laid-Open No. 2003-172141 (Patent Document 1) discloses an engine cooling device that improves the responsiveness of cooling water temperature control performed to adjust the temperature of cooling water circulating through the engine to a target temperature. Yes. The device adjusts the flow rate adjustment valve that adjusts the flow rate of cooling water that passes through the radiator provided in the cooling water circulation path of the engine, and the opening degree of the flow rate adjustment valve so that the engine outlet water temperature becomes the required target temperature. An ECU for controlling, and the ECU sets a basic opening as a feedforward term based on the operating state of the engine, and F / B as a feedback term that is increased or decreased so that the engine outlet water temperature becomes the target temperature. The final opening is calculated from the constant and the basic opening, and the opening of the flow rate adjusting valve is feedback controlled based on the final opening.

JP 2003-172141 A JP-A-5-231148

  The feedforward control in the technique of Patent Document 1 simply sets the opening of the flow rate adjustment valve based on the operating state of the engine at a certain point in time, and does not consider the operating state before that point. For this reason, for example, when the engine is in a certain operating state after the engine is fully opened, or when the engine is in a certain operating state after the idling state, the opening of the flow rate adjustment valve is set. Will be the same. However, the engine holding heat amount (engine temperature, engine water temperature) differs depending on the operating state before the “certain operating state”, so the flow adjustment valve opening is set to be the same in feedforward control. There is a risk that the transition of the engine water temperature (engine water temperature control status) from a certain point in time will be different (the control error will increase).

An object of the present invention is to provide a cooling water control device for an internal combustion engine that can control the water temperature of the cooling water for the internal combustion engine to a more optimal water temperature.
Another object of the present invention is to provide a cooling water control device for an internal combustion engine capable of improving the control response of the cooling water temperature of the internal combustion engine with respect to the optimum water temperature.

  The cooling water control device for an internal combustion engine of the present invention is a cooling water control device for an internal combustion engine that controls a coolant temperature of the internal combustion engine using a valve opening adjusting means that can electronically adjust the valve opening. Cooling water optimum value estimating means for estimating an optimum value of the cooling water temperature based on the operating conditions of the internal combustion engine up to the present time, and an estimated value of the cooling water temperature at the inlet of the internal combustion engine in the future, The valve opening degree of the valve opening degree adjusting means is adjusted based on the estimated optimum value of the coolant temperature.

  In the cooling water control apparatus for an internal combustion engine of the present invention, the cooling water optimum value estimation means estimates the current combustion chamber wall temperature of the internal combustion engine based on the current operating conditions of the internal combustion engine, and The optimum value of the coolant temperature is estimated based on the estimated value of the combustion chamber wall temperature.

  In the cooling water control apparatus for an internal combustion engine according to the present invention, the cooling water optimum value estimation means may determine the future combustion chamber wall based on the estimated value of the current combustion chamber wall temperature and the current operating condition of the internal combustion engine. The temperature is estimated, and the optimum value of the coolant temperature is estimated based on the estimated value of the future combustion chamber wall temperature.

  The cooling water control device for an internal combustion engine of the present invention is a cooling water control device for an internal combustion engine that controls the temperature of the cooling water of the internal combustion engine, and an estimated value of the coolant temperature at the inlet of the internal combustion engine in the future, Based on the control target value, the water temperature of the cooling water entering the internal combustion engine is feedforward controlled. Here, the control target value may be an optimum value of the estimated coolant temperature.

  The cooling water control apparatus for an internal combustion engine according to the present invention is a cooling water control apparatus for an internal combustion engine that controls the temperature of the cooling water for the internal combustion engine, the current combustion chamber wall temperature of the internal combustion engine, and the current internal combustion engine. The future combustion chamber wall temperature is estimated on the basis of the operating conditions, and the optimum value of the cooling water temperature is estimated on the basis of the estimated value of the future combustion chamber wall temperature. The water temperature of the cooling water is feedforward controlled based on the estimated value of the optimum value.

  In the cooling water control apparatus for an internal combustion engine according to the present invention, a calorific value is calculated based on a current operating condition of the internal combustion engine, and based on a current coolant water temperature at the inlet of the internal combustion engine and the calorific value. The temperature of the cooling water at the outlet of the internal combustion engine in the future is estimated, and the future temperature of the radiator is estimated based on the estimated value of the temperature of the cooling water at the outlet of the future internal combustion engine and the cooling capacity of the radiator. Estimating the coolant temperature at the outlet, based on the estimated value of the coolant temperature at the outlet of the future internal combustion engine and the estimated value of the coolant temperature at the outlet of the future radiator, It is characterized in that an estimated value of the coolant temperature at the inlet of a future internal combustion engine is obtained.

  According to the present invention, it is possible to control the coolant temperature of the internal combustion engine to a more optimal water temperature.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  An embodiment of a cooling water control apparatus for an internal combustion engine will be described with reference to FIGS.

  In the present embodiment, a thermostat that controls the engine water temperature of the internal combustion engine is computerized, and in an optimal water temperature control according to the load, the future engine inlet water temperature is estimated from the combustion chamber wall temperature and the current operating condition values, By quickly feedforward (prefetching) controlling the opening of the electronic thermostat toward the optimum water temperature, the control response of the water temperature is improved, the knocking avoidance accuracy is improved, and the fuel consumption is improved.

  FIG. 1 is a system configuration diagram of a cooling water control device for an internal combustion engine according to the present embodiment. In the figure, reference numeral 1 is an engine, reference numeral 2 is an air cleaner, reference numeral 3 is a throttle, reference numeral 4 is a surge tank, reference numeral 5 is an intake manifold, reference numeral 6 is an exhaust manifold, and reference numeral 7 is an exhaust pipe. As a cooling system of the basic system configuration of these engines, there are a water outlet (W / O) pipe 8, a radiator 9, a water inlet (W / I) pipe 10, and a water bypass (W / B) pipe 11. . An electronic thermostat 12 is provided at a connection portion between the W / I pipe 10 and the W / B pipe 11.

  The electronic thermostat 12 controls the opening degree of the passage path of the cooling water sent to the inside of the engine 1 by the water pump 13. As shown in FIG. 2, the electronic thermostat 12 uses a passage switching valve 12 a to change the flow rate of low-temperature cooling water flowing through the radiator 9 and the W / I pipe 10 in the cooling water entering the engine 1, and the radiator 9. The flow rate of the high-temperature cooling water flowing through the W / B pipe 11 without passing through is controlled so that the cooling water adjusted to the optimum water temperature enters the engine 1.

  As shown in FIG. 1, a water temperature sensor (engine inlet) 15 is provided on the W / I pipe 10 closer to the engine 1 than the electronic thermostat 12. Similarly, a water temperature sensor (engine outlet) 16 is provided on the W / O pipe 8 on the engine 1 side. The ECU 14 includes a signal (vehicle speed signal) 17 indicating a vehicle speed detected by a vehicle speed sensor (not shown) provided on the output shaft of the transmission, a signal indicating the outside air temperature, a water temperature sensor 15 at the engine inlet, and an engine outlet. A signal indicating the water temperature detected by each of the water temperature sensors 16, a signal indicating the engine speed detected by the engine speed (NE) sensor 18, and a signal indicating the throttle opening detected by the throttle position sensor 19. Are entered. As described below, the ECU 14 obtains the optimum value of the engine water temperature based on these input signals and controls the passage switching valve 12a of the electronic thermostat 12.

  Next, the operation of the present embodiment will be described with reference to FIG.

[Step S1 and Step S2]
The control of the engine coolant according to the present embodiment is executed by the ECU 14 when the engine 1 is in operation (Step S1, Step S11). When the engine 1 is in operation (steps S1-Y and S11-Y), based on the current engine operating conditions (throttle opening and engine speed) and the engine operating conditions up to the present time in step S2. An estimated value of the wall temperature of the combustion chamber of the engine 1 at the present time is obtained, and based on the estimated value of the wall temperature of the combustion chamber of the engine 1 at the present time and the current operating condition of the engine, The transition of the wall temperature is calculated (estimated).

  As described above, in step S2, first, an estimated value of the wall temperature of the combustion chamber of the engine 1 at the present time is obtained. The wall temperature of the combustion chamber of the engine 1 at this time is not determined only by the current operating state of the engine 1, but is a value that changes depending on the operating state of the engine 1 from the start of the engine 1 to the current time. Therefore, the current wall temperature of the combustion chamber of the engine 1 is estimated not only based on the current engine operating conditions but also based on the integrated value of the engine operating conditions from the start of the engine 1 to the current time. The estimated value of the wall temperature of the combustion chamber of the engine 1 at this time substantially reflects the amount of heat retained by the engine (the temperature of each part of the engine and the water temperature in the engine).

  Since combustion phenomena such as knocking and abnormal combustion are easily affected by the wall temperature of the combustion chamber, the wall temperature of the combustion chamber is estimated in step S2. The wall temperature of the combustion chamber can be estimated based on the water temperature value at the inlet of the engine 1 in addition to the throttle opening (load) and the engine speed.

  In addition, in step S2, the future transition of the wall temperature of the combustion chamber is based on the assumption that the current estimated temperature of the combustion chamber wall of the engine 1 will be It is required from the viewpoint of how it changes (changes). In the next control cycle, if the current engine operating conditions change, the future change in the combustion chamber wall temperature is corrected by the updated (updated) operating conditions.

[Step S3]
Next, in step S3, the optimum value of the engine water temperature is calculated based on the future transition (estimated value) of the combustion chamber wall temperature obtained in step S2. As the optimum value of the engine water temperature, a value suitable for the combustion chamber wall temperature is required in terms of performance and fuel consumption.

  FIG. 4 shows an example of the relationship between the current combustion chamber wall temperature (estimated value) and the future transition (estimated value) of the combustion chamber wall temperature and the optimum value of the engine water temperature. As shown in the figure, when it is estimated that the combustion chamber wall temperature will increase from the present to the future, the optimum value of the engine water temperature is determined to decrease. In step S3, the time t1 set at the control timing is obtained. The value at is calculated as the optimum value of the engine water temperature.

[Step S4]
Next, in step S4, the heat generation amount of the engine 1 is calculated based on the current engine operating conditions, and based on the heat generation amount and the current coolant temperature measured by the water temperature sensor 15 at the engine inlet. Thus, the arrival point of the outlet water temperature of the engine 1 in the future is estimated. The amount of heat generated per unit time of the engine 1 calculated in step S4 can be obtained from a map of engine speed (NE) and throttle opening as shown in FIG. As shown in the figure, the heat value of the engine 1 is calculated to be larger as the engine speed is larger and the throttle opening is larger.

[Step S5]
Next, in step S5, the current cooling capacity of the radiator 9 is calculated based on the vehicle speed (vehicle speed signal 17) and the outside air temperature. The cooling capacity of the radiator 9 calculated in step S5 can be obtained from a map of vehicle speed and outside air temperature as shown in FIG. As shown in the figure, the higher the vehicle speed and the lower the outside air temperature, the larger the cooling capacity of the radiator 9 is calculated.

[Step S6]
Next, in step S6, the outlet water temperature of the engine 1 estimated in step S4, the current engine speed (flow rate of the water pump 13) detected by the NE sensor 18, and the passage switching valve 12a of the electronic thermostat 12 are displayed. The future outlet water temperature of the radiator 9 is estimated on the basis of the current opening of the radiator 9 and the current cooling capacity of the radiator 9 calculated in step S5.

[Step S7]
Next, in step S7, the future outlet water temperature of the engine 1 estimated in step S4, the future outlet water temperature of the radiator 9 estimated in step S6, and the current passage switching valve 12a of the electronic thermostat 12 are opened. The future inlet water temperature of the engine 1 is estimated based on the degree.

[Step S8 to Step S13]
Next, in step S8, it is determined whether or not the future inlet water temperature of the engine 1 estimated in step S7 is higher than the optimum value of the engine water temperature calculated in step S3. As a result of the determination, if the estimated inlet water temperature of the engine 1 is higher than the optimum water temperature value, it is determined whether or not the passage switching valve 12a of the electronic thermostat 12 is fully open to the radiator 9 side (step S9). If not, the passage switching valve 12a is controlled so as to flow a predetermined amount of cooling water from the radiator 9 (increase the passage on the W / I pipe 10 side) (step S10). On the other hand, as a result of the determination in step S8, if the estimated inlet water temperature of the engine 1 is not higher than the optimum water temperature value, whether or not the passage switching valve 12a of the electronic thermostat 12 is fully opened to the W / B pipe 11 side is determined. If it is determined (step S12) and it is not fully opened, the passage switching valve 12a is controlled so that the cooling water from the radiator 9 flows in a predetermined amount less (a passage on the W / B pipe 11 side is enlarged). (Step S13). If the determination in step S9 or step S12 is affirmative, and after step S10 or step S13, the process proceeds to step S11. If the engine 1 is in operation, the process returns to step S2, and if not in operation. This control ends.

  As described above, in this embodiment, in the system in which the thermostat for controlling the engine water temperature is electronically controlled, the controllability with respect to the set water temperature is based on the feedforward control based on the mere engine operating state or the water temperature at the outlet of the electronic thermostat. Do not rely on feedback control. That is, in this embodiment, as a determination index for setting the optimum value of the engine water temperature, first, the wall temperature (estimated value) of the current combustion chamber is set, and the current engine temperature is set to the current combustion chamber wall temperature. A future combustion chamber wall temperature is set in consideration of the operation state (step S2). The optimum value of the engine water temperature is obtained from the future combustion chamber wall temperature (step S3), and feedforward control aiming at the optimum value of the engine water temperature is performed to improve knocking avoidance accuracy and improve fuel efficiency. I am going to do that.

  In the present embodiment, the engine inlet water temperature (the engine rotational speed, the throttle opening, the engine inlet water temperature, the vehicle speed, the outside air temperature, the opening of the passage switching valve 12a of the electronic thermostat 12) based on the current operating conditions. (Future value) is estimated (step S7), and pre-reading control (feed forward control) is performed on the passage switching valve 12a of the electronic thermostat 12 (step S8 to step S13), thereby determining the combustion chamber wall temperature (estimated value). It is intended to improve the controllability to the optimum value of the required engine water temperature. When the combustion chamber wall temperature (low / medium load) does not cause knocking, the engine water temperature is quickly increased to improve fuel efficiency (reduction in cooling loss) and the combustion chamber wall temperature (high) that causes knocking. Under the condition of (load), the engine water temperature is quickly lowered, so that knocking is less likely to occur and the performance can be improved.

  In other words, in the present embodiment, knocking is not based on the combustion chamber wall temperature (estimated value) reflecting the engine operating state from the start of the engine to the present, but based on the engine operating state at a certain point in time. Whether the fuel is likely to occur or a state where fuel efficiency can be improved is determined, and the engine water temperature is controlled based on the determination.

  Furthermore, in the present embodiment, not only the feedback control with the optimum value of the engine water temperature as a control target, but also the rapid feedforward (prefetch) control, not only the improvement of the followability of the engine water temperature, The convergence of the engine water temperature control is also improved (engine water temperature hunting is less likely to occur, and the control target value is easily stabilized). This is because the opening degree of the passage switching valve 12a of the electronic thermostat 12 is set from both sides of the feedback control and the feedforward control.

It is a schematic block diagram of one Embodiment of the cooling water control apparatus of the internal combustion engine of this invention. It is a figure for demonstrating the electronic thermostat of one Embodiment of the cooling water control apparatus of the internal combustion engine of this invention. It is a flowchart which shows operation | movement of one Embodiment of the cooling water control apparatus of the internal combustion engine of this invention. It is a figure which shows the relationship between combustion chamber wall temperature and optimal water temperature value in one Embodiment of the cooling water control apparatus of the internal combustion engine of this invention. It is a figure for demonstrating the calculation method of the emitted-heat amount in one Embodiment of the cooling water control apparatus of the internal combustion engine of this invention. It is a figure for demonstrating the cooling capacity of a radiator in one Embodiment of the cooling water control apparatus of the internal combustion engine of this invention.

Explanation of symbols

1 Engine 2 Air Cleaner 3 Throttle 4 Surge Tank 5 Intake Manifold 6 Exhaust Manifold 7 Exhaust Pipe 8 Water Outlet (W / O) Pipe 9 Radiator 10 Water Inlet (W / I) Pipe 11 Water Bypass (W / B) Pipe 12 Electronic Thermostat 12a Passage switching valve 13 Water pump 14 ECU
15 Water temperature sensor (engine inlet)
16 Water temperature sensor (engine outlet)
17 Vehicle speed signal 18 NE sensor

Claims (6)

A cooling water control device for an internal combustion engine that controls the temperature of the cooling water for the internal combustion engine using a valve opening adjustment means capable of electronically adjusting the valve opening,
A cooling water optimum value estimating means for estimating an optimum value of the temperature of the cooling water based on the current operating conditions of the internal combustion engine;
The valve opening of the valve opening adjusting means is adjusted based on an estimated value of the coolant temperature at the inlet of the internal combustion engine in the future and an optimum value of the estimated coolant temperature. A cooling water control device for an internal combustion engine. The cooling water control apparatus for an internal combustion engine according to claim 1,
The cooling water optimum value estimation means estimates the current combustion chamber wall temperature of the internal combustion engine based on the current operating conditions of the internal combustion engine, and based on the estimated value of the current combustion chamber wall temperature, An optimum value of the coolant temperature is estimated. A coolant control device for an internal combustion engine. The cooling water control device for an internal combustion engine according to claim 2,
The cooling water optimum value estimation means estimates the future combustion chamber wall temperature based on the estimated value of the current combustion chamber wall temperature and the current operating condition of the internal combustion engine, and the future combustion chamber wall temperature. An optimum value of the coolant temperature is estimated based on the estimated value of the coolant. A cooling water control device for an internal combustion engine for controlling a coolant temperature of the internal combustion engine,
A feedforward control of the coolant temperature entering the internal combustion engine based on an estimated value of the coolant temperature at the inlet of the internal combustion engine in the future and an optimum value of the estimated coolant temperature; An internal combustion engine cooling water control device. A cooling water control device for an internal combustion engine for controlling a coolant temperature of the internal combustion engine,
Based on the current combustion chamber wall temperature of the internal combustion engine and the current operating conditions of the internal combustion engine, the future combustion chamber wall temperature is estimated, and based on the estimated value of the future combustion chamber wall temperature, An optimum value of the coolant temperature is estimated, and the coolant temperature is feedforward controlled based on the optimum value of the coolant temperature. The cooling water control apparatus for an internal combustion engine according to any one of claims 1 to 5,
A calorific value is calculated based on the current operating conditions of the internal combustion engine, and a future cooling at the outlet of the internal combustion engine based on the current coolant temperature at the inlet of the internal combustion engine and the calorific value. Estimating the water temperature of the water, estimating the water temperature of the cooling water at the outlet of the future internal combustion engine, and estimating the water temperature of the cooling water at the outlet of the radiator based on the cooling capacity of the radiator, Based on the estimated value of the coolant temperature at the outlet of the future internal combustion engine and the estimated value of the coolant temperature at the outlet of the future radiator, the coolant temperature at the inlet of the future internal combustion engine A cooling water control apparatus for an internal combustion engine, characterized in that an estimated value is obtained.

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