JP2015140718A - throttle valve opening learning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of controlling a gas flow rate by a throttle valve by improving the accuracy of the feedforward term of the throttle valve opening degree. SOLUTION: Using a nozzle type in which a throttle valve is modeled, a measured value of pressure on the upstream side of the throttle valve, a measured value of pressure on the downstream side of the throttle valve, a measured value of temperature on the upstream side of the throttle valve, The effective opening area of the throttle valve is calculated from the measured value of the flow rate of the gas passing through or passing through the throttle valve. Then, based on the control value of the throttle valve opening degree and the calculated value of the effective opening area, the correlation between the throttle valve opening degree and the effective opening area is learned. [Selection diagram] Fig. 5

Description

  The present invention relates to a throttle valve opening learning device suitable for use in feedforward control of the throttle valve opening of an internal combustion engine.

  The following patent document discloses an invention relating to a learning device that learns the correlation between the opening of a throttle provided in an intake passage of an internal combustion engine and the amount of intake air. According to the present invention, during the idling operation of the internal combustion engine, the ignition timing of the internal combustion engine is corrected, and the throttle opening is changed so as to cancel the torque change due to the correction of the ignition timing in order to maintain the target idle rotation speed. Is done. Then, correlation data between the opening and the intake air amount is acquired at each changed opening, and the correlation between the throttle opening and the intake air amount is learned based on the obtained plurality of correlation data. Is called.

JP 2007-092711 A

  According to the invention disclosed in the above patent document, it is possible to learn the correlation between the throttle opening and the intake air amount in the idling operation. However, idle operation is only one of the operating conditions of the internal combustion engine. For example, when the operating conditions of the compression ignition type internal combustion engine are expressed by the rotational speed and the injection amount, there are a large number of operating conditions as shown in the graph of FIG.

  FIG. 8 is a graph in which correlation data between the throttle closing degree and the intake air amount in each operating condition including the idle condition is acquired and plotted on a graph having the throttle closing degree and the intake air amount as axes. In a compression ignition internal combustion engine, the throttle is basically fully open, and is controlled to the closed side with reference to the fully open. For this reason, not the opening degree but the closing degree may be used as an index for measuring the opening degree of the throttle. However, since the throttle opening degree and the closing degree are in a one-to-one relationship, determining the closing degree of the throttle is substantially equivalent to determining the opening degree.

  FIG. 8 shows that the correlation between the throttle closing degree and the intake air amount is low under a plurality of operating conditions. This is because the pressure and temperature before and after the throttle change depending on the operating conditions, thereby causing a variation in the relationship between the throttle closing degree and the intake air amount. In intake air amount control by the throttle, it is important to accurately calculate the feedforward term of the throttle opening in order to improve the control response. Accurate calculation of the feedforward term requires a model that matches the actual flow characteristics of the throttle. However, there is no high correlation between the throttle opening and the intake air amount under operating conditions other than the idle condition. For this reason, an accurate feedforward term cannot be obtained from the relationship between the throttle opening and the intake air amount.

  The present invention has been made in view of the above-described problems, and an object thereof is to obtain an accurate feedforward term in the calculation of the throttle opening for achieving the target air amount. .

  In order to achieve the above object, the throttle valve opening degree learning apparatus according to the present invention is configured to perform the following operations.

  According to the present invention, the throttle valve opening learning device includes a throttle valve opening control value (hereinafter referred to as throttle valve opening control value) and a pressure value measured upstream of the throttle valve (hereinafter referred to as throttle valve upstream). Pressure measurement value), pressure measurement value downstream of the throttle valve (hereinafter referred to as throttle valve downstream pressure measurement value), temperature measurement value upstream of the throttle valve (hereinafter referred to as throttle valve upstream temperature measurement value), A measured value of the flow rate of the gas passing through or passing through the throttle valve (hereinafter referred to as a throttle valve passing gas flow rate measured value) is acquired. Using the nozzle type with the throttle valve modeled, the throttle valve effectiveness is determined from the throttle valve upstream pressure measurement value, throttle valve downstream pressure measurement value, throttle valve upstream temperature measurement value, and throttle valve passage gas flow rate measurement value. A calculated value of the opening area (hereinafter, an effective opening area calculated value) is calculated, and a correlation between the opening of the throttle valve and the effective opening area is learned based on the throttle valve opening control value and the effective opening area calculated value.

  According to a preferred embodiment of the method for learning the correlation between the opening of the throttle valve and the effective opening area, first, when the opening of the throttle valve is in the first opening range, the throttle valve opening control value and the effective opening are used. First correlation data with the calculated area value is acquired, and then the throttle valve opening control value is effective when the throttle opening is in a second opening range different from the first opening range. Second correlation data with the calculated aperture area value is acquired. Then, based on the first correlation data and the second correlation data, the slope and intercept of a linear expression representing the correlation between the opening of the throttle valve and the effective opening area are calculated and stored as learning values.

  According to the present invention, the correlation between the opening of the throttle valve and the effective opening area can be learned. There is a high correlation between the opening of the throttle valve and the effective opening area, which is not affected by operating conditions. Therefore, the target value of the effective opening area is calculated from the target flow rate using the nozzle equation, and based on the learned correlation between the opening of the throttle valve and the effective opening area, the target value of the effective opening area is calculated from the target value of the effective opening area. By determining the opening, an accurate feedforward term can be obtained.

It is a figure showing composition of an engine system concerning an embodiment of the invention. It is a figure which shows the calculation flow of the throttle closing degree command value performed in embodiment of this invention. It is a figure which shows the calculation flow of the F / F term of the throttle closing degree command value performed in embodiment of this invention. It is a figure which shows the correlation with a throttle closing degree and an effective opening area. It is a figure which shows the learning flow of the correlation with the throttle closing degree and effective opening area which are performed by embodiment of this invention. It is a figure explaining the learning method of the correlation between throttle closing degree and an effective opening area. It is a figure which shows the example of an operating condition defined by rotation speed and injection amount. It is a figure which shows the correlation with a throttle closing degree and the amount of intake air.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of an engine system as an embodiment of the present invention. The internal combustion engine of the present embodiment is a diesel engine with a turbocharger (hereinafter simply referred to as an engine). The engine body 2 is provided with four cylinders in series, and an injector 8 is provided for each cylinder. An intake manifold 4 and an exhaust manifold 6 are attached to the engine body 2. An intake passage 10 through which fresh air taken in from the air cleaner 20 flows is connected to the intake manifold 4. A turbocharger compressor 14 is attached to the intake passage 10. A throttle 24 that is a throttle valve is provided downstream of the compressor 14 in the intake passage 10. An intercooler 22 is provided between the compressor 14 and the throttle 24 in the intake passage 10. The exhaust manifold 6 is connected to an exhaust passage 12 for releasing the exhaust gas emitted from the engine body 2 into the atmosphere. A turbocharger turbine 16 is attached to the exhaust passage 12. A catalyst device 26 for purifying exhaust gas is provided downstream of the turbine 16 in the exhaust passage 12.

  The engine of the present embodiment includes an EGR device that recirculates exhaust gas from the exhaust system to the intake system. In the EGR device, a position downstream of the throttle 24 in the intake passage 10 and the exhaust manifold 6 are connected by an EGR passage 30. An EGR valve 32 is provided in the EGR passage 30. An EGR cooler 34 is provided on the exhaust side of the EGR valve 32 in the EGR passage 30. The EGR passage 30 is provided with a bypass passage 36 that bypasses the EGR cooler 34. A bypass valve 38 that switches the direction in which the exhaust gas flows is provided at a location where the EGR passage 30 and the bypass passage 36 merge.

  The engine system of the present embodiment includes an ECU (Electronic Control Unit) 50. The ECU 50 is a control device that comprehensively controls the entire engine system. The ECU 50 captures and processes a sensor signal provided in the engine system. Sensors are installed in various parts of the engine system. An air flow meter 58 for measuring the flow rate of fresh air taken into the intake passage 10 is attached to the intake passage 10 downstream of the air cleaner 20. Between the intercooler 22 and the throttle 24, a pressure sensor (hereinafter referred to as a throttle upstream pressure sensor) 56 for measuring the pressure in the intake passage 10 upstream of the throttle 24 and the intake passage 10 in the upstream of the throttle 24. A temperature sensor (hereinafter referred to as a throttle upstream temperature sensor) 60 for measuring the temperature is attached. A pressure sensor (hereinafter referred to as a throttle downstream pressure sensor) 54 for measuring the pressure in the intake passage 10 downstream of the throttle 24 is attached downstream of the throttle 24. The throttle 24 is integrated with a sensor that outputs a signal corresponding to the control value of the closing degree. Furthermore, a rotation speed sensor 52 that detects rotation of the crankshaft, an accelerator opening sensor 62 that outputs a signal corresponding to the opening of the accelerator pedal, and the like are also provided. The ECU 50 processes the signals of the acquired sensors and operates various actuators including the throttle 24 according to a predetermined control program. There are many actuators and sensors connected to the ECU 50 other than those shown in the figure, but the description thereof is omitted in this specification.

  The engine control executed by the ECU 50 includes new air amount control by the throttle 24. The fresh air amount control is one of intake air amount controls, and means control related to the amount of fresh air in the intake air. The new air amount control includes new air amount control by the throttle 24 and new air amount control by the EGR valve 32. Of these, since the present invention relates to the new air amount control by the throttle 24, this will be described below. While the new air amount control by the throttle 24 is being performed, the EGR valve 32 is fully opened or opened to a predetermined value.

  FIG. 2 is a diagram showing an outline of the new air amount control by the throttle 24 executed in the present embodiment. The new air amount control by the throttle 24 includes feedforward control and feedback control. In the feedforward control, a feedforward term (denoted as F / F term in the figure) of the throttle closing degree is calculated from a target fresh air amount using a throttle model that models the flow rate characteristics of the throttle 24. The target fresh air amount is determined from the engine speed and the injection amount. In the feedback control, a feedback term (denoted as F / B term in the figure) is calculated by proportional-integral control from the deviation between the target fresh air amount and the actual fresh air amount measured by the air flow meter 58. The sum of the feedforward term and the feedback term is output to the throttle 24 as a command value for throttle closing.

An overview of the feedforward control of the present embodiment is shown in FIG. In the present embodiment, a nozzle equation including the following equations (1) to (4) is used as a throttle model related to feedforward control. In the following equation, μA is effective opening area [cm ² ], ga is fresh air volume [kg / sec], ethia is throttle upstream temperature [K], epim is throttle downstream pressure [Pa], and P3 is throttle upstream pressure [ Pa] and R are gas constants (287 J / K * kg), and κ is a specific heat ratio (1.4).

  In the feedforward control, the target effective opening area of the throttle 24 is calculated from the target fresh air amount using the above-described nozzle equation. The target effective opening area includes the measured value of the throttle upstream pressure measured using the throttle upstream pressure sensor 56, the measured value of the throttle downstream pressure measured using the throttle downstream pressure sensor 54, and the throttle upstream temperature sensor 60. The measured value of the temperature upstream of the throttle measured using is used as a parameter. Then, the feedforward term of the throttle closing degree is determined from the target effective opening area.

  For determining the feedforward term, a calculation formula corresponding to the relationship (μA characteristic) between the degree of closure of the throttle 24 and the effective opening area is used. FIG. 4 is a plot of data collected under each operating condition shown in FIG. 7 in a graph with the throttle closing degree and the effective opening area as axes. From this graph, it can be seen that there is a high correlation between the throttle closing degree and the effective opening area that is not affected by the operating conditions, and the correlation can be approximated by a linear expression. The ECU 50 stores the slope and intercept of the linear expression as data for specifying a linear expression that represents the correlation between the throttle closing degree and the effective opening area.

  In the present embodiment, the use range of the throttle 24 in the fresh air amount control is limited to a range from a closing degree of 60% as a lower limit value to a closing degree of 90% as an upper limit value. The upper limit value of the throttle closing degree is determined corresponding to the minimum air amount. On the other hand, the lower limit value of the throttle closing degree is a determination reference value for switching from the new air amount control by the throttle 24 to the new air amount control by the EGR valve 32. When the target effective opening area is larger than the effective opening area corresponding to the lower limit value of the throttle closing degree, the closing degree of the throttle 24 is fixed to the lower limit value, and the new air amount control by the EGR valve 32 is performed. In a situation where the throttle closing degree is lower than the lower limit value, that is, in a situation where the throttle 24 is opened to some extent, the response of air to the operation of the throttle 24 is low. In such a situation, it is possible to control the fresh air amount with higher accuracy by controlling the EGR amount or the EGR rate according to the opening degree of the EGR valve 32 and thereby indirectly controlling the fresh air amount.

  The above-described μA characteristics not only vary depending on individual differences for each throttle, but also vary with time. If there is an error in the μA characteristic, an accurate feedforward term cannot be obtained, and the exhaust gas performance or fuel consumption may be deteriorated due to a decrease in control response. For this reason, in the present embodiment, the correlation between the throttle closing degree and the effective opening area is learned, and the slope and intercept values of the primary expression stored in the memory of the ECU 50 are updated.

  FIG. 5 shows a learning flow for correlation between the throttle closing degree and the effective opening area, which is executed by the ECU 50 in the present embodiment. A program corresponding to this learning flow is stored in the memory of the ECU 50. When this program is executed by the processor of the ECU 50, the ECU 50 functions as a throttle valve opening learning device according to the present invention.

  According to the learning flow shown in FIG. 5, the engine speed is measured in step S1, the injection amount is determined based on the accelerator opening in step S2, and the target fresh air amount based on the rotation speed and injection amount is determined in step S3. Determination and actual fresh air volume are measured in step S4. In step S5, it is determined whether or not the EGR valve 32 is fully opened. Alternatively, it is determined whether or not the EGR valve 32 has an opening greater than or equal to a predetermined value. When the EGR valve 32 is not fully opened (or when the opening is not equal to or greater than a predetermined value), the fresh air amount control is performed based on the opening of the EGR valve 32. In this case, steps S1 to S4 are repeated until the EGR valve 32 is fully opened.

  When the EGR valve 32 is fully opened (or when the opening is equal to or greater than a predetermined value), the new air amount control by the throttle 24 is performed in step S6. The target effective opening area is calculated from the target fresh air amount using the nozzle equation, and the feedforward term of the throttle opening is calculated from the target effective opening area based on the μA characteristic. Further, a feedback term is calculated based on the deviation between the target fresh air amount and the actual fresh air amount.

  In step S7, it is determined whether or not the throttle closing degree determined by the fresh air amount control falls within a predefined control usage range. If the throttle closing degree does not fall within the control usage range, that is, if the throttle closing degree is below the lower limit value, the process of step S15 is performed. In step S15, the throttle closing degree is fixed to the lower limit value, and the fresh air amount control by the EGR valve 32 is performed. The fresh air amount control by the EGR valve 32 is continued until the EGR valve 32 is fully opened again (or until the opening degree becomes a predetermined value or more again) in the determination of step S5.

  When the throttle closing degree falls within the control usage range, first, at step S8, it is determined whether or not the throttle closing degree falls within the predefined closing degree range A. If the throttle closing degree is not in the closing degree region A, it is next determined in step S9 whether or not the throttle closing degree is in a predefined closing degree region B. Here, the closed area A can be defined as a range from 60% to 70%, for example, and the closed area B can be defined as a range from 80% to 90%, for example. That is, the closed area A and the closed area B do not have to overlap. The closed area A corresponds to the “first opening range” in the present invention, and the closed area B corresponds to the “second opening range” in the present invention.

  When the throttle closing degree is within the closing degree region A and when the throttle closing degree is within the closing degree region B, the processing of step S10 to step S12 is performed in each case. In step S10, the control value of the current throttle closing degree is acquired, and the measured values of the fresh air amount, the throttle upstream pressure, the throttle upstream temperature, and the throttle downstream pressure are acquired. In step S11, the measured values of fresh air amount, throttle upstream pressure, throttle upstream temperature, and throttle downstream pressure acquired in step S10 are input to the nozzle equation to calculate the effective opening area. The effective opening area calculated here corresponds to an estimated value of the actual effective opening area that realizes the actual fresh air amount. In step S12, the effective opening area calculated in step S11 and the control value of the throttle closing degree acquired in step S10 are associated and stored in the memory as one correlation data.

  In step S13, it is confirmed whether or not the correlation data has been recorded in both the closed area A and the closed area B. The processes up to step S13 are repeated until both pieces of correlation data are obtained.

  And when the correlation data of both the closed area A and the closed area B are prepared, the process of step S14 is performed. In step S14, a linear expression representing the correlation between the throttle closing degree and the effective opening area is specified using the two correlation data. In the graph of FIG. 6, the primary expression before learning is drawn with a broken line, and the primary expression after learning is drawn with a solid line. As shown in this graph, two correlation data are plotted on a graph with the throttle closing degree and the effective opening area as axes, and a straight line that passes through them is obtained to identify a linear expression that matches the current μA characteristics. be able to. The ECU 50 as the throttle valve opening learning device calculates the slope and intercept of the identified primary equation, and updates the learned values of the slope and intercept stored in the memory, respectively. For the next calculation of the feedforward term, a linear expression after learning specified by the updated slope and intercept is used.

  By the way, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, there may be three or more pieces of correlation data used for specifying a linear expression representing the correlation between the throttle closing degree and the effective opening area. However, if the correlation data is acquired in the closeness range close to the upper limit of the throttle usage range and the closeness range close to the lower limit, two correlation data are sufficient as in the above-described embodiment. I can say that. According to the above-described embodiment, the correlation between the throttle closing degree and the effective opening area can be accurately learned in a very short time.

  The throttle valve opening learning device according to the present invention can be applied not only to a throttle of a compression ignition type internal combustion engine but also to a throttle of a spark ignition type internal combustion engine. When the present invention is applied to the throttle of a spark ignition type internal combustion engine, the correlation between the throttle opening and the effective opening area may be learned instead of the throttle closing degree. Furthermore, the throttle valve opening degree learning device according to the present invention is widely applicable not only to the throttle disposed in the intake passage but also to a throttle valve used for flow rate control. For example, if the EGR valve is a throttle valve that can be modeled by a nozzle equation, the present invention can also be applied to learning of the opening degree of the EGR valve. The present invention is also applicable to learning of the opening degree of the variable nozzle of the turbocharger turbine.

  The present invention is also applicable to the case where the correlation between the opening of the throttle valve and the effective opening area is expressed by a function other than the linear expression. By obtaining the required number of correlation data between the throttle valve opening control value and the effective opening area calculation value, the coefficient of the function representing the correlation can be obtained.

2 Engine body 4 Intake manifold 6 Exhaust manifold 10 Intake passage 12 Exhaust passage 14 Compressor 16 Turbine 24 Throttle 30 EGR passage 32 EGR valve 50 ECU
52 Rotational Speed Sensor 54 Throttle Downstream Pressure Sensor 56 Throttle Upstream Pressure Sensor 58 Air Flow Meter 60 Throttle Upstream Temperature Sensor

Claims (2)

Means for obtaining a throttle valve opening control value which is a control value of the throttle valve opening of the internal combustion engine;
Means for obtaining a throttle valve upstream pressure measurement value which is a measurement value of the pressure upstream of the throttle valve;
Means for obtaining a throttle valve downstream pressure measurement value which is a measurement value of the pressure downstream of the throttle valve;
Means for obtaining a throttle valve upstream temperature measurement value which is a measurement value of the temperature upstream of the throttle valve;
Means for obtaining a throttle valve passage gas flow rate measurement value that is a measurement value of a flow rate of gas passing through or passing through the throttle valve;
Using the nozzle type in which the throttle valve is modeled, the throttle valve upstream pressure measurement value, the throttle valve downstream pressure measurement value, the throttle valve upstream temperature measurement value, and the throttle valve passage gas flow rate measurement value, Means for calculating an effective opening area calculated value which is a calculated value of the effective opening area;
Based on the throttle valve opening control value and the effective opening area calculation value, learning means for learning the correlation between the opening of the throttle valve and the effective opening area;
A throttle valve opening learning device comprising:   The learning means includes first correlation data between the throttle valve opening control value acquired when the throttle valve opening is in a first opening range and the calculated effective opening area, and the throttle valve. Based on the second correlation data between the throttle valve opening control value and the calculated effective opening area obtained when the opening is in a second opening range different from the first opening range. 2. The throttle valve opening according to claim 1, wherein a slope and an intercept of a linear expression representing a correlation between an opening of the throttle valve and an effective opening area are calculated, and the slope and the intercept are stored as learning values. Degree learning device.

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