JP2008184987A - Device for correcting air flow rate measurement value - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for correcting air flow rate measurement value capable of easily and suitably correcting measurement error caused by pulsation of intake air targeting at output signal of an air flow rate measurement sensor measuring flow rate of intake air in an intake air passage. <P>SOLUTION: The device for correcting air flow rate measurement value (ECU for engine control) correcting output signal of an air flow meter measuring flow rate of intake air in the intake air passage is provided with a program (rotation speed correction part B2) correcting actual engine rotation speed (measurement value by a crank angle sensor) based on acoustic velocity in the intake air (based on a correction coefficient K1 according to acoustic velocity in details), and a program (sensor output correction part B4) correcting output signal of the targeted air flow meter based on throttle valve opening Ta and corrected engine rotation speed Ne2 corrected by the rotation speed correction part B2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an air flow rate measurement value correction device that is applied to, for example, an air flow meter (air flow rate measurement sensor) used for measuring the flow rate of intake air in an automobile engine control system and corrects its output signal.

  In an automotive engine control system, various air flow meters such as a movable flap type or a hot wire (hot wire) type are used to measure the flow rate of intake air introduced into a cylinder (more specifically, a combustion chamber) through an intake passage. Alternatively, a Karman vortex type air flow meter may be used. In particular, hot wire airflow meters are generally widely used at present. This hot wire type utilizes a cooling action by air circulation. Specifically, this hot wire type air flow meter includes a wire as a heated element that is heated according to a current amount (energization amount). Then, at the time of measurement, by controlling the current supply amount (and hence the energization amount), the wire is heated to a constant temperature, and the wire cooling amount corresponding to the air flow rate, and further the current change amount corresponding to the cooling amount. Based on this, an electrical signal (output signal) indicating the air flow rate at that time is output.

  However, even with these air flow meters, it is not always possible to measure the intake flow rate of the target engine with high accuracy. Depending on the operating state of the engine, the measurement error (the difference between the air flow rate indicated by the output signal of the air flow meter and the actual air flow rate) may increase, and correction may be necessary. For example, when a strong pulsation occurs due to resonance of the intake flow, for example, the backflow of the intake air is concerned, and when the backflow occurs in the intake flow, the measurement error of the air flow meter becomes large. Specifically, in general air flow meters, including the hot wire air flow meter described above, the air flow rate is detected without distinguishing the direction of air flow, so even when a reverse flow occurs in the air flow, the forward direction As with the air flow, the flow rate is measured. Therefore, when a reverse flow occurs in the intake flow, the measurement error of the air flow meter becomes large according to the degree of the reverse flow.

Therefore, conventionally, as in the device described in Patent Document 1, for example, the output of the air flow meter is output using a correction coefficient map using the opening degree of the throttle valve (intake throttle valve), the engine speed, and the intake air temperature as parameters. There has been proposed an air flow rate measurement value correction device that corrects a signal. According to the apparatus having such a configuration, the sensor output is corrected based on the values of parameters (the intake throttle valve opening, the engine rotational speed, and the intake air temperature) that affect the pulsation of the intake air, and the measurement caused by the pulsation described above is performed. The error can be compensated.
JP 9-133547 A

  However, the intake air temperature is not directly related in principle to the measured value of the air flow meter, and thus is difficult to handle as a parameter for obtaining a correction coefficient for the measured value of the air flow meter. Specifically, when the intake air temperature is used as a parameter of the correction coefficient map, for example, as in the device described in Patent Document 1, the relationship between the intake air temperature and the measured value of the air flow meter is experimentally determined in advance. It is necessary to obtain the correction coefficient map, and enormous labor, cost, and time are required to create the correction coefficient map. That is, even with the above-described apparatus, there is still room for improvement in this respect.

  The present invention has been made in view of such circumstances, and it is easier and more suitable for measurement errors caused by pulsation of intake air with respect to an output signal of an air flow measurement sensor that measures the flow rate of intake air in the intake passage. An object of the present invention is to provide an air flow rate measurement value correction device that can correct the air flow rate.

  Hereinafter, means for solving the above-described problems and the effects thereof will be described.

  According to the first aspect of the present invention, an intake throttle valve that changes the flow rate according to the valve opening is generated by fuel combustion based on a reaction between intake air and fuel introduced into the cylinder through an intake passage provided in the middle. In an air flow rate measurement value correction device that is applied to an engine that rotates an output shaft by the torque that is applied and corrects an output signal of an air flow rate measurement sensor that measures the flow rate of intake air in the intake passage, the opening degree of the intake throttle valve In order to compensate for the measurement error according to the state at that time, which is defined by the engine rotation speed that is the rotation speed of the engine output shaft and the sound speed related to the intake air, the engine rotation speed, the intake throttle valve opening, and Sensor output correcting means for correcting an output signal of the air flow rate measuring sensor based on a value of sound velocity is provided.

  The inventor has invented the above-mentioned device, paying attention to the speed of sound as a parameter that directly affects the measured value of the air flow measurement sensor (air flow meter) in principle. The speed of sound related to intake (the speed of sound in the intake area) corresponds to the propagation speed of intake pulsation. When comparing the speed of sound related to intake and the temperature, in principle, the sound speed is higher than the temperature. It has a more direct connection to sensor readings. Therefore, the sound velocity is more effective than the intake air temperature for compensating the measurement error of the air flow rate sensor. Therefore, according to the above configuration, the measurement error caused by the pulsation of the intake air can be corrected more easily and suitably for the output signal of the air flow rate measurement sensor that measures the flow rate of the intake air in the intake passage. It becomes like this.

  According to a second aspect of the present invention, in the apparatus according to the first aspect, an actual value of the engine rotational speed (for example, a rotation detection sensor provided on the engine output shaft) based on a value of sound velocity related to the intake air. (Measured value) by the sensor output correction means based on the corrected engine rotation speed corrected by the rotation speed correction means and the opening of the intake throttle valve, The output signal of the air flow measurement sensor is corrected.

  The inventor noticed that the influence of the sound speed on the measurement value of the air flow measurement sensor can be considered in the same dimension as the influence of the engine rotation speed on the measurement value of the sensor. Invented. In this apparatus, the measurement error caused by the sound speed is converted into the measurement error caused by the engine rotation speed by the rotation speed correction means, and the measurement errors are combined into one by the sensor output correction means. It can be compensated collectively as a measurement error caused by the engine speed. In such a device, by combining the measurement error due to the sound speed and the measurement error due to the engine rotation speed into one, for example, a correction coefficient deriving means composed of a map, a mathematical expression, etc. is used to correct both values in common. When the coefficient is derived, the number of parameters of the correction coefficient deriving unit can be reduced to reduce the size of the unit. As a result, the labor for creating the means is reduced, and it is easy to secure a storage area (storage capacity) as a storage location for the correction coefficient deriving means.

  Specifically, as in the invention according to claim 3, in the apparatus according to claim 2, the measured value of the engine rotational speed is Ne1, the corrected value of the engine rotational speed is Ne2, and the intake air When the predetermined reference value of the sound speed is Sp0 and the current value of the sound speed is Sp1, the rotational speed correction means is based on the relational expression “Ne2 = Ne1 × (Sp0 / Sp1)”. It is effective to adopt a configuration that corrects the measured value of the speed. According to such a configuration, the measurement error caused by the sound speed and the measurement error caused by the engine rotation speed are combined into one based on the relational expression, so that both values can be easily shared with high accuracy. A correction factor can be derived.

  Further, regarding the device according to claim 2 or 3, as in the invention according to claim 4, a plurality of values defined by both values of the opening degree of the intake throttle valve and the corrected engine rotational speed are used. Correction coefficient deriving means for associating one correction coefficient with each state (for example, a correction coefficient map or a mathematical expression using the opening degree of the intake throttle valve and the corrected engine rotation speed as parameters), and the correction coefficient deriving means Referring to one correction coefficient (the opening degree of the intake throttle valve and the engine rotation speed) uniquely determined by the corrected engine rotation speed corrected by the rotation speed correction means and the opening degree of the intake throttle valve. And correction coefficient acquisition means for acquiring a correction coefficient for compensating a measurement error due to the sound speed related to intake air, and the sensor output correction means includes the correction coefficient acquisition means. Wherein In the structure is intended to correct the output signal of the air flow measuring sensor, it is possible to realize the above-described configuration easily and appropriately by using the obtained correction factor by.

  By the way, in the apparatus according to any one of claims 1 to 4, a method for measuring a sound velocity related to intake air (a sound velocity of an intake portion) is arbitrary. For example, the speed of sound can be calculated by detecting the pulsation period from the output signal of the air flow measurement sensor. However, when considering practicality, it is effective to have a configuration including sound speed acquisition means for obtaining the sound speed related to the intake air based on the temperature of the intake air, as in the fifth aspect of the invention. In general engine control, a sensor for detecting the intake air temperature is used. For this reason, by setting it as the said structure, it becomes possible to implement | achieve the said structure more easily using such a known sensor.

  In the sixth aspect of the present invention, the intake throttle valve that changes the flow rate according to the valve opening is generated by fuel combustion based on the reaction between the intake air and the fuel introduced into the cylinder through the intake passage provided in the middle. In an air flow rate measurement value correction device that is applied to an engine that rotates an output shaft by the torque that is applied and corrects an output signal of an air flow rate measurement sensor that measures the flow rate of intake air in the intake passage, the opening degree of the intake throttle valve The air flow rate is determined based on the values of the intake throttle valve opening and the pulsation period or pulsation frequency in order to compensate for the measurement error according to the current state, which is defined by the pulsation period or pulsation frequency related to the intake air. Sensor output correction means for correcting the output signal of the measurement sensor is provided.

  The inventor also paid attention to parameters such as a pulsation period and a pulsation frequency along with the above-mentioned sound speed. Both the pulsation period and the pulsation frequency are parameters that are directly related to the measurement value of the air flow rate measurement sensor rather than the temperature, like the speed of sound. Therefore, the pulsation period and the pulsation frequency are more effective than the intake air temperature for compensating the measurement error of the air flow measurement sensor. Therefore, according to the above configuration, the measurement error caused by the pulsation of the intake air can be corrected more easily and suitably for the output signal of the air flow rate measurement sensor that measures the flow rate of the intake air in the intake passage. It becomes like this.

In addition, it is more effective for the apparatus according to claim 6 to include a pulsation parameter deriving means for obtaining a pulsation period or a pulsation frequency related to the intake air by a predetermined method. Specifically, for example, as in the invention described in claim 7,
A pulsation parameter deriving unit that obtains a pulsation period or a pulsation frequency related to the intake air based on a sound speed related to the intake air and an engine rotation speed that is a rotation speed of the engine output shaft.
Or like invention of Claim 8,
-As the air flow measurement sensor to be corrected, or separately from the air flow measurement sensor, based on the output signal of a sensor for measuring the flow rate of intake air provided in the intake passage, A pulsation parameter deriving unit for obtaining a pulsation period or a pulsation frequency.
Or like invention of Claim 9,
A pulsation parameter deriving unit that obtains a pulsation cycle or a pulsation frequency related to the intake air based on an output signal of a pressure sensor that measures the pressure of the intake air in the intake passage.
It is particularly effective to have a configuration including such pulsation parameter deriving means. According to the configurations of the seventh to ninth aspects, a series of processes from derivation of pulsation parameters (pulsation period or pulsation frequency) (for example, calculation and estimation based on various sensor outputs and the like) to output correction of the air flow measurement sensor. Can be performed in the air flow rate measurement value correction apparatus, and the derivation accuracy (accuracy) of the pulsation parameter can be expected to be relatively high with the above-described configurations. Become.

  The pulsation parameter (pulsation period or pulsation frequency) can be obtained as long as any one of the three types of pulsation parameter deriving means described in claims 7 to 9 is provided. However, it is also effective to use a combination of two or more of these means for the purpose of increasing the derivation accuracy. For example, depending on the application and the like, it is also effective to switch two or more means depending on the situation or to average the pulsation parameter values obtained by the two or more means.

  With regard to the device according to any one of claims 1 to 9, as in the invention according to claim 10, the measured value of the engine rotational speed based on the value of the pulsation period or pulsation frequency related to the intake air. For example, the sensor output correction means is corrected by the rotation speed correction means so as to include a rotation speed correction means for correcting (for example, a measured value by a rotation detection sensor provided on the engine output shaft). It is effective to correct the output signal of the air flow measurement sensor based on the later engine speed and the opening of the intake throttle valve. In this way, when a correction coefficient deriving means composed of, for example, a map or a mathematical expression is used, a common correction coefficient is derived for both the measurement error caused by the pulsation period or pulsation frequency and the measurement error caused by the engine rotation speed. In addition, the number of parameters of the correction coefficient deriving means can be reduced to reduce the size of the means. As a result, the labor for creating the means is reduced, and it is easy to secure a storage area (storage capacity) as a storage location for the correction coefficient deriving means.

  In addition, in the apparatus as described in any one of the said Claims 1-10, arbitrary sensors can be employ | adopted in principle as an air flow rate measurement sensor made into the object of the said correction | amendment. However, it has already been confirmed by the inventor that at least a hot wire type air flow meter tends to cause a measurement error due to intake pulsation. Therefore, in the invention according to any one of the first to tenth aspects, as in the invention according to the eleventh aspect, an air flow rate measuring sensor to be corrected is provided in the intake passage. It is particularly effective when applied to a configuration that is a hot wire type air flow meter.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment embodying an air flow rate measurement value correction apparatus according to the present invention will be described with reference to the drawings. Note that the apparatus according to the present embodiment is mounted on an engine control system for a reciprocating engine as an engine for a four-wheeled vehicle, for example.

  First, a schematic configuration of an engine control system in which an air flow rate measurement value correction apparatus according to this embodiment is mounted will be described with reference to FIG. Note that a multi-cylinder (for example, in-line 4-cylinder) engine is assumed as a control target of the present embodiment. However, in FIG. 1, only one cylinder (cylinder) is shown for convenience of explanation.

  As shown in FIG. 1, this engine control system rotates a crankshaft 10d (the illustrated portion is a pulsar gear mounted on the crankshaft) as an output shaft by torque generated through combustion in a cylinder 20. The engine 10 (internal combustion engine) is set as a control target, and includes various sensors for controlling the engine 10, an ECU (electronic control unit) 50, and the like.

  The engine 10 to be controlled here is a spark ignition type reciprocating engine, and basically includes a cylinder 20 formed by a cylinder block 10a. The cylinder block 10a is provided with a cooling water channel 10b for circulating the cooling water in the engine 10, and a water temperature sensor 10c for detecting the temperature (cooling water temperature) of the cooling water in the water channel 10b. The engine 10 is cooled by water. Also, a piston 20a is accommodated in the cylinder 20, and a crankshaft 10d as an output shaft is rotated by the reciprocating motion of the piston 20a. On the outer peripheral side of the crankshaft 10d, a crank angle sensor 10e that outputs a crank angle signal at every predetermined crank angle (for example, at a cycle of 30 ° CA) is disposed, and the rotation angle (engine rotation speed) of the crankshaft 10d is arranged. Can be detected. A cylinder head is fixed to the upper end surface of the cylinder block 10a, and a combustion chamber 20b is formed between the cylinder head and the crown surface of the piston 20a.

  The cylinder head is formed with an intake port (intake port) and an exhaust port (exhaust port) that open to the combustion chamber 20b. These intake port and exhaust port are each attached to a camshaft that is linked to the crankshaft 10d. It is opened and closed by an intake valve 21 and an exhaust valve 22 driven by a cam (not shown). An intake pipe 30 (intake manifold) for sucking outside air (fresh air) into each cylinder of the engine 10 is connected to the intake port, and combustion gas (exhaust gas) from each cylinder of the engine 10 is connected to the exhaust port. ) Is connected to an exhaust pipe 40 (exhaust manifold). In the middle of the intake pipe 30, a surge tank 30a having a passage area enlarged (expanded diameter) is provided for the purpose of preventing intake pulsation and intake interference. The camshaft includes variable valve timing devices 11 and 12 (one of variable valve mechanisms) and a cam position sensor 11a on the intake side and exhaust side, respectively, as valve mechanisms for the intake valve 21 and the exhaust valve 22. 12a is provided.

  In the intake pipe 30 (intake passage) constituting the intake system of the engine 10, in order to detect the amount of fresh air drawn through the air cleaner 31 at the most upstream part of the intake pipe 30, the above-described hot wire (hot wire) type air flow is used. A meter 32a (air flow rate measuring sensor) and an intake air temperature sensor 32b for detecting the intake air temperature downstream are provided. Further, on the downstream side of the intake air temperature sensor 32b, an electronically controlled throttle valve 33 (intake throttle valve) whose opening is electronically adjusted by an actuator such as a DC motor, and the opening (throttle throttle) of the throttle valve 33 are provided. A throttle opening sensor 33a for detecting valve opening) and movement (opening fluctuation), and the amount of air sent to the surge tank 30a provided downstream thereof according to the valve opening. It can be adjusted (the flow rate is variable).

  Further, the intake pipe 30 is branched so as to introduce air into each cylinder of the engine 10 on the downstream side of the surge tank 30a. An electromagnetic drive type (or piezo drive type) injector 35 (fuel injection valve) that injects and supplies fuel in the vicinity of the intake port of each cylinder is attached to the branch path of the intake pipe 30. Thus, fuel (gasoline) is supplied by injection (port injection) to the intake passage, particularly the intake port of each cylinder.

  In the engine 10, the fuel injected by the injector 35 (strictly speaking, the mixture with intake air) is ignited to burn the fuel. For this reason, a spark plug 15 including an ignition device 15a made of an ignition coil or the like is attached to the cylinder head of the engine 10 for each cylinder. That is, when the engine 10 is ignited, the ECU 50 applies a high voltage to the spark plug 15 at a desired ignition timing. Then, by applying this high voltage, a spark discharge is generated between the opposing electrodes of each spark plug 15, and this generated spark discharge ignites the air-fuel mixture introduced into the combustion chamber 20 b, thereby The fuel burns based on the reaction. The engine 10 is a 4-stroke engine. That is, in the engine 10, one combustion cycle by four strokes of intake, compression, combustion, and exhaust is sequentially executed at a “720 ° CA” cycle.

  On the other hand, the exhaust pipe 40 (exhaust passage) constituting the exhaust system of the engine 10 is, for example, a three-way catalyst that purifies CO, HC, NOx, etc. in the exhaust as an exhaust aftertreatment system for purifying exhaust. And an oxygen concentration sensor 41a (for example, a linear detection type A / F sensor or a binary sensor) for detecting the air-fuel ratio or rich / lean of the air-fuel mixture with respect to the exhaust gas. A detection type O2 sensor or the like is provided.

  In such a system, the ECU 50 is a part that functions as the air flow rate measurement value correction apparatus of the present embodiment and performs engine control mainly as an electronic control unit. In addition to the various sensors described above, detection signals from various sensors such as an accelerator sensor 50a for detecting the amount of accelerator operation (accelerator opening) by the driver (driver) are sequentially input to the ECU 50. The ECU 50 grasps the operating state of the engine 10 and the user's request based on the detection signals of the various sensors, and operates various actuators such as the injector 35 in accordance with the operation state, so that the optimum according to the situation at the time. In this manner, various controls relating to the engine 10 are performed.

  More specifically, the ECU 50 includes a known microcomputer (not shown). The microcomputer basically includes a CPU (basic processing device) for performing various calculations, a RAM (Random Access Memory) as a main memory for temporarily storing data and calculation results during the calculation, ROM (read-only storage device) as a program memory, EEPROM (electrically rewritable non-volatile memory) as a data storage memory, backup RAM (RAM powered by a backup power source such as an in-vehicle battery), and Consists of various arithmetic devices such as A / D converters and clock generation circuits, input / output ports for inputting / outputting signals to / from the outside, storage devices, signal processing devices, communication devices, etc. Has been. The ROM stores various programs and control maps related to engine control including the program related to the measurement value correction processing of the air flow meter 32a, and the data storage memory (EEPROM) stores the design of the engine 10. Various control data including data are stored in advance.

  By the way, the air flow rate measurement value correction device (ECU 50) of this embodiment is also the output of an air flow meter 32a (air flow rate measurement sensor) that measures the flow rate of intake air in the intake passage, as in the device described in Patent Document 1 described above. A measurement error (particularly an error on the increase side) due to the pulsation of the intake air is corrected for the signal. However, in the apparatus according to the present embodiment, the correction can be performed more easily and suitably by adopting a configuration in which the correction coefficient is obtained using the sound speed related to the intake air as a parameter.

  Hereinafter, an example of the fuel injection control using the measurement value correction process of the air flow meter 32a, that is, the fuel injection control incorporating the correction process will be described in detail with reference to FIGS. In these drawings, FIG. 2 is a block diagram showing the ECU 50, in particular, the part related to the measured value correction processing of the air flow meter 32a, divided into functions. FIG. 3 is a flowchart showing a processing procedure for an example of the fuel injection control including the correction process, and FIG. 4 is a graph showing a correction coefficient map used for the correction process. Here, description will be made in accordance with the processing procedure of the fuel injection control shown in FIG.

  The processing of FIG. 3 is basically executed sequentially at predetermined crank angles or at predetermined time intervals by executing a program stored in the ROM by the ECU 50. The values of various parameters used in the series of processes are stored as needed in a storage device such as a RAM, EEPROM, or backup RAM mounted on the ECU 50, and updated as necessary.

  As shown in FIG. 3, in this series of processing, first, in step S11, based on the output signal of the crank angle sensor 10e, the rotation angle of the crankshaft 10d (engine rotation speed Ne1) at that time is calculated. In the subsequent step S12, the intake air temperature Tha1 at that time is detected by the intake air temperature sensor 32b.

  In the subsequent step S13, the rotational speed correction coefficient acquisition unit B1 (FIG. 2) calculates the sound speed related to the intake air based on the intake air temperature Tha1 acquired in step S12, and calculates the correction coefficient K1 corresponding to the sound speed. To do.

Specifically, when the predetermined reference value of the intake air temperature (reference intake air temperature) is Tha0, the predetermined reference value of the sound velocity related to the intake air is Sp0, and the value of the sound velocity at that time (actual value corresponding to the intake air temperature Tha1) is Sp1. ,
Sp0 = 331.5 + 0.6 × Tha0 (Formula 1)
Sp1 = 331.5 + 0.6 × Tha1 (Formula 2)
K1 = Sp0 / Sp1 (Formula 3)
The correction coefficient K1 is calculated based on the following relational expressions (Expression 1) to (Expression 3).

  In step S14 subsequent to step S13, the engine rotational speed Ne1 (actually measured value by the crank angle sensor 10e) is corrected based on the correction coefficient K1, and the correction is a corrected value of the engine rotational speed Ne1. The rear engine speed Ne2 is acquired. Specifically, the rotation speed correction unit B2 (FIG. 2) performs a correction operation (here, multiplication) of “Ne2 = Ne1 × K1” to calculate the corrected engine rotation speed Ne2.

  Further, in the subsequent step S15, the opening degree Ta of the throttle valve 33 at that time is detected by the throttle opening degree sensor 33a. In subsequent step S16, the output signal of the air flow meter 32a is corrected based on the throttle valve opening degree Ta detected in step S15 and the corrected engine rotational speed Ne2 calculated in step S14. A correction coefficient K2 is obtained.

  Specifically, the correction coefficient K2 acquisition process is performed by the correction coefficient acquisition unit B3 (correction coefficient acquisition means) referring to a correction coefficient map (correction coefficient derivation means) created in advance through experiments or the like. FIG. 4 shows an example of the correction coefficient map as a graph. This correction coefficient map is an example that the inventor has actually created by calculating an optimum value (adapted value) through experiments or the like.

  As shown in the graph of FIG. 4, in this map, the relationship (correction characteristic) between the correction coefficient K2 (vertical axis of the graph) and the engine rotational speed Ne (horizontal axis of the graph) is the magnitude of the throttle valve opening Ta. Seven types are defined accordingly. As shown in FIG. 4, all of these seven types of correction characteristics are farthest from a minimum point (“K2 = 1” without correction) at one point (“2000 rpm” in this example) of the engine speed Ne. As the engine rotational speed Ne becomes larger or smaller than the minimum point, the correction coefficient K2 associated with the rotational speed Ne becomes larger (corresponding to “K2 = 1”). )

  On the other hand, in these seven types of correction characteristics (graphs), correction coefficients K2 of different magnitudes are associated with the above-mentioned minimum point (“2000 rpm”), and the correction coefficient K2 over the entire range of the engine rotation speed Ne. The value is also in accordance with the value of the correction coefficient K2 at the minimum point (if the correction coefficient K2 is smaller than the other correction characteristics at the minimum point, the correction coefficient K2 has other correction values over the entire engine speed. Smaller than the characteristic). Each of these seven types of correction characteristics includes seven types of throttle valve opening Ta (in this example, “20” “40” “50” “60” “70” “80” “85”). "Deg"). Specifically, among the seven types of opening Ta, a smaller opening among the seven types of correction characteristics (graphs) is associated with a smaller opening. That is, with respect to the throttle valve opening degree Ta, the smaller the opening degree Ta is, the larger the correction coefficient K2 associated with the opening degree Ta is (closer to “K2 = 1”).

  As described above, in this map, one correction is made for each of a plurality of states defined by both values of the throttle valve opening degree Ta and the engine speed Ne (corresponding to the corrected engine speed Ne2 in this embodiment). The coefficient K2 is associated. That is, in step S16, referring to such a correction coefficient map, one correction coefficient uniquely determined by the throttle valve opening degree Ta detected in step S15 and the corrected engine speed Ne2 calculated in step S14. Get K2. Specifically, first, one correction characteristic is selected from the seven types of correction characteristics (graphs) according to the value of the throttle valve opening Ta. Next, a correction coefficient K2 (graph vertical axis) corresponding to the post-correction engine rotational speed Ne2 (graph horizontal axis) is acquired based on the selected correction characteristic. When the data interval of the map is large (coarse) and there is no corresponding value (Ne2 or K2) on the map, etc., it is possible to compensate for the missing value by appropriately interpolating between the data. It is valid.

  The correction for the measurement value of the air flow meter 32a described above is performed by the correction coefficient K2 acquired in step S16. That is, in the subsequent step S17, the current measured value (sensor output value Ga1) of the air flow meter 32a is acquired, and in the subsequent step S18, the acquired sensor output value Ga1 is corrected based on the correction coefficient K2 and corrected. A sensor output value Ga2 is obtained. Specifically, the sensor output correction unit B4 (sensor output correction means, FIG. 2) performs a correction operation (multiplication here) of “Ga2 = Ga1 × K2” to calculate a corrected sensor output value Ga2.

  In the subsequent step S19, the fuel injection amount (opening of the injector 35) that satisfies the target air-fuel ratio (for example, the theoretical air-fuel ratio) is based on the corrected sensor output value Ga2 (and hence the fresh air amount indicated by this value Ga2). (Corresponding to the valve time) is calculated, and fuel injection by the injector 35 is executed at the fuel injection amount in synchronism with the fuel injection timing separately set based on the engine operating state or the like.

  As described above, in the present embodiment, the output signal of the air flow meter 32a (air flow measurement sensor) is corrected through the processing of FIG. 3, and the intake air amount, and hence the fuel injection amount, is obtained based on the corrected output signal. ing. As a result, the fuel injection amount is controlled with high accuracy.

  According to the air flow rate measurement value correction apparatus according to the present embodiment described above, the following excellent effects can be obtained.

  (1) A throttle valve 33 is used as an air flow measurement value correction device (engine control ECU 50) for correcting an output signal of an air flow meter 32a (air flow measurement sensor) that measures the flow rate of intake air in the intake pipe 30 (intake passage). Measurement according to the current state (engine operating state) defined by the opening degree of the (inlet throttle valve), the engine rotational speed that is the rotational speed of the engine output shaft (crankshaft 10d), and the sound speed related to intake air A configuration including a program (sensor output correction means, sensor output correction unit B4 in FIG. 2) for correcting the output signal of the air flow meter 32a based on the values of the engine speed, throttle valve opening, and sound speed in order to compensate for the error. It was. More specifically, a program (rotational speed correction means) for correcting an actual measured value (measured value by the crank angle sensor 10e) of the engine rotational speed based on the value of the sound speed related to intake air (specifically, based on the correction coefficient K1 corresponding to the acoustic speed). The rotation speed correction unit B2) of FIG. For the sensor output correction unit B4, the corrected engine rotation speed (corrected engine rotation speed Ne2) corrected by the rotation speed correction unit B2 and the opening degree of the throttle valve 33 (throttle valve opening degree Ta) are corrected. Based on the above, the output signal of the air flow meter 32a is corrected. With such a device, a correction error map (correction coefficient derivation means, a correction coefficient derivation means, and a correction error map for deriving a common correction coefficient for both values by combining the measurement error due to the sound speed and the measurement error due to the engine rotation speed into one. The size of the map can be reduced (simplified) by reducing the number of parameters shown in FIG. As a result, the trouble of creating the map is reduced, and it is easy to secure a storage area (storage capacity) as a storage location of the map.

  (2) When the measured value of the engine rotational speed is Ne1, the corrected value of the engine rotational speed is Ne2, the predetermined reference value of the sound speed related to the intake air is Sp0, and the current value of the sound speed is Sp1, The speed correction unit B2 is configured to correct the measured value of the engine speed based on the relational expression “Ne2 = Ne1 × (Sp0 / Sp1)”. According to such a configuration, the measurement error caused by the sound speed and the measurement error caused by the engine rotation speed are combined into one based on the relational expression, so that both values can be easily shared with high accuracy. A correction factor can be derived.

  (3) a correction coefficient map (correction coefficient deriving means, FIG. 4) for associating one correction coefficient with each of a plurality of states defined by both values of the throttle valve opening Ta and the corrected engine rotational speed Ne2, Referring to the correction coefficient map, a program (correction coefficient acquisition means, correction coefficient acquisition unit B3) that acquires one correction coefficient K2 that is uniquely determined by the corrected engine rotational speed Ne2 and the throttle valve opening Ta. It was set as the structure provided. And about the said sensor output correction | amendment part B4, this shall correct the output signal of the said air flow meter 32a using the correction coefficient K2. By doing so, the above configuration can be realized more easily and accurately.

  (4) It is configured to include a program (sound speed acquisition means, the above (Expression 1) to (Expression 3)) for determining the sound speed based on the temperature of intake air. By doing so, the above configuration can be realized more easily by using the known intake air temperature sensor 32b.

  (5) The correction target air flow rate measurement sensor is a hot wire type air flow meter 32a. Thereby, the measurement error caused by the intake pulsation described above, which is of particular concern in the hot wire type air flow meter, can be accurately compensated through the processing of FIG.

  The above embodiment may be modified as follows.

  The correction coefficient map illustrated in FIG. 4 is merely an example, and the configuration of the correction coefficient map used in the apparatus according to the present invention is not limited to this. For example, in the above embodiment, in order to reduce (simplify) the size of the correction coefficient map, prior to derivation of the correction coefficient K2 for correcting the output signal of the air flow meter 32a, the measurement error due to the sound speed and the engine rotation speed are reduced. By obtaining the correction coefficient K1 that compensates for the measurement error caused by the batch, the parameters of the map are reduced to two, that is, the corrected engine rotational speed Ne2 and the throttle valve opening degree Ta based on the correction coefficient K1 ( So-called two-dimensional map). However, instead of this, a three-dimensional correction coefficient map having three parameters, that is, the speed of sound related to intake air, the engine rotational speed Ne1, and the throttle valve opening degree Ta, may be used. In this case, it is not necessary to obtain the correction coefficient K1. As shown in FIG. 5, the relationship between the engine rotational speed Ne and the correction coefficient K2 indicates that the minimum point of the correction coefficient K2 formed at one point of the engine rotational speed Ne described above increases as the sound speed increases. The sound speed characteristic that shifts to the high speed side of the speed Ne is shown. Therefore, the above three-dimensional map can be created by reflecting these characteristics in the graph illustrated in FIG.

  In general, since a hot wire type air flow meter has a built-in intake air temperature sensor, the air flow meter built-in sensor may be substituted for the intake air temperature sensor 32b.

  -The method of measuring the speed of sound related to intake (the speed of sound in the intake portion) is arbitrary. For example, the speed of sound may be calculated by calculating a pulsation period and a pulsation frequency from the output signal of the air flow measurement sensor.

  A pulsation period or pulsation frequency related to intake air may be used instead of the sound speed related to intake air (the sound speed of the intake air portion). In this case, for example, the embodiment is partially changed, and the pulsation period or pulsation frequency related to the inspiration is obtained in step S12 of FIG. 3, and based on the pulsation period or pulsation frequency in subsequent step S13. (For example, based on the degree of deviation from the reference value), the correction coefficient K1 is calculated. Even with such a configuration, the same effect as the effect (1) or an effect equivalent thereto can be obtained.

  In this case, as a program (pulsation parameter deriving means) for obtaining the pulsation period or pulsation frequency related to intake air in step S12, for example, the sound speed related to intake air (for example, calculated by (Equation 2)) and the rotational speed of the engine output shaft ( It is effective to use a program for obtaining a pulsation period or a pulsation frequency related to the intake air based on the engine rotation speed (for example, calculated from the sensor output of the crank angle sensor 10e). Specifically, for example, a predetermined map created in advance by experiment etc. and written with a suitable value (estimated value) of the pulsation period or pulsation frequency for each sound speed and each engine rotation speed (for example, stored in a ROM or a mathematical expression) Is used to obtain the pulsation parameter (the pulsation period or pulsation frequency associated with inspiration).

  Alternatively, the output signal of the air flow meter 32a (or an air flow meter newly added to the intake pipe 30 separately from this) is sequentially acquired, and the pulsation period or pulsation frequency of the intake air is determined from the output signal (and its waveform). The program to calculate is also effective. Incidentally, the output deviation related to the absolute amount (sensitivity) in the output of the air flow meter 32a does not become a big trouble in calculating the pulsation period or pulsation frequency of the intake air. For this reason, even when the output of the air flow meter 32a to be corrected, in other words, the sensor output before correction is used, the pulsation period or pulsation frequency of the intake air can be calculated with sufficiently high accuracy.

  Alternatively, a pressure sensor for measuring the pressure of the intake air is added to the intake pipe 30 (intake passage) (for example, in the vicinity of the intake temperature sensor 32b), and the output signal of the pressure sensor is sequentially acquired, and the output signal A program for calculating the pulsation period or pulsation frequency of intake air from (and its waveform) is also effective.

  With these programs (pulsation parameter deriving means), the pulsation parameter (pulsation period or pulsation frequency related to inspiration) can be obtained with relatively high accuracy. It is also effective to use a combination of any two or all three of the above three types of programs for the purpose of increasing the derivation accuracy (estimation accuracy and calculation accuracy) of pulsation parameters. For example, depending on the application or the like, a configuration in which a program to be used is switched according to the situation or an average of pulsation parameter values obtained by two or more programs is effective.

  The correction target air flow rate measurement sensor is not limited to the hot wire type air flow meter, and the other air flow rate measurement sensors (for example, a movable flap type air flow meter and a Karman vortex type air flow meter) are also described above. It is effective to apply the present invention if a measurement error due to the intake pulsation occurs.

  The type of engine to be controlled (including in-cylinder gasoline engine, compression ignition diesel engine, etc.) and system configuration can be changed as appropriate according to the application.

  In the embodiment and the modification, it is assumed that various kinds of software (programs) are used. However, similar functions may be realized by hardware such as a dedicated circuit.

The block diagram which shows the outline of the engine control system to which this apparatus was applied about one Embodiment of the air flow rate measured value correction | amendment apparatus which concerns on this invention. The block diagram which showed the part which concerns on the measured value correction | amendment process of the airflow meter of the same apparatus as a block according to the function. The flowchart which shows the process sequence about an example of fuel-injection control including the correction process. The graph which shows the correction coefficient map used for the correction process. The graph which shows the modification of a correction coefficient map.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Engine, 10d ... Crankshaft, 10e ... Crank angle sensor, 20 ... Cylinder (cylinder), 30 ... Intake pipe, 32a ... Air flow meter, 32b ... Intake temperature sensor, 33 ... Throttle valve, 40 ... Exhaust pipe, 50 ... ECU (electronic control unit).

Claims (11)

An engine that rotates an output shaft by torque generated by fuel combustion based on a reaction between intake air and fuel introduced into a cylinder through an intake passage provided in the middle of an intake throttle valve whose flow rate is variable according to the valve opening degree In the air flow rate measurement value correction device that corrects the output signal of the air flow measurement sensor that measures the flow rate of the intake air in the intake passage,
In order to compensate for the measurement error according to the state at that time, which is defined by the opening degree of the intake throttle valve, the engine rotation speed which is the rotation speed of the engine output shaft, and the sound speed related to the intake air, An air flow rate measurement value correction device comprising sensor output correction means for correcting an output signal of the air flow rate measurement sensor based on values of speed, intake throttle valve opening and sound velocity. Rotational speed correction means for correcting the measured value of the engine rotational speed based on the value of the sound speed related to the intake air,
The sensor output correction means corrects the output signal of the air flow rate measurement sensor based on the corrected engine rotation speed corrected by the rotation speed correction means and the opening degree of the intake throttle valve. Item 2. The air flow rate measurement value correction device according to Item 1.   When the measured value of the engine rotational speed is Ne1, the corrected value of the engine rotational speed is Ne2, the predetermined reference value of the sound speed related to the intake air is Sp0, and the current value of the same sound speed is Sp1, the rotational speed correction 3. The air flow rate measurement value correction device according to claim 2, wherein the means corrects the actual measurement value of the engine rotation speed based on a relational expression of “Ne2 = Ne1 × (Sp0 / Sp1)”. Correction coefficient deriving means for associating one correction coefficient with each of a plurality of states defined by both values of the opening degree of the intake throttle valve and the corrected engine rotation speed;
With reference to the correction coefficient derivation means, a correction coefficient acquisition means for acquiring one correction coefficient uniquely determined by the corrected engine rotation speed corrected by the rotation speed correction means and the opening of the intake throttle valve When,
4. The air flow rate measurement value according to claim 2, wherein the sensor output correction unit corrects the output signal of the air flow rate measurement sensor using the correction coefficient acquired by the correction coefficient acquisition unit. Correction device.   The air flow rate measurement value correction apparatus according to any one of claims 1 to 4, further comprising a sound speed acquisition unit that calculates a sound speed related to the intake air based on the temperature of the intake air. An engine that rotates an output shaft by torque generated by fuel combustion based on a reaction between intake air and fuel introduced into a cylinder through an intake passage provided in the middle of an intake throttle valve whose flow rate is variable according to the valve opening degree In the air flow rate measurement value correction device that corrects the output signal of the air flow measurement sensor that measures the flow rate of the intake air in the intake passage,
The intake throttle valve opening and the pulsation period or pulsation frequency are defined in terms of the opening of the intake throttle valve and the pulsation cycle or pulsation frequency related to the intake air, in order to compensate for the measurement error according to the state at that time. And a sensor output correcting means for correcting the output signal of the air flow measuring sensor based on the value of the air flow measuring sensor.   The measured air flow rate according to claim 6, further comprising pulsation parameter deriving means for obtaining a pulsation period or a pulsation frequency related to the intake air based on a sound speed related to the intake air and an engine rotation speed that is a rotation speed of the engine output shaft. Correction device.   As the air flow measurement sensor to be corrected or separately from the air flow measurement sensor, the pulsation related to the intake air based on the output signal of the sensor that measures the flow rate of the intake air provided in the intake passage The air flow rate measurement value correcting device according to claim 6, further comprising a pulsation parameter deriving unit for obtaining a period or a pulsation frequency.   The air flow rate measurement value correction device according to claim 6, further comprising a pulsation parameter deriving unit that obtains a pulsation period or a pulsation frequency related to the intake air based on an output signal of a pressure sensor that measures an intake air pressure in the intake passage. Rotational speed correction means for correcting the measured value of the engine rotational speed based on the value of the pulsation period or pulsation frequency related to the intake air,
The sensor output correction means corrects the output signal of the air flow rate measurement sensor based on the corrected engine rotation speed corrected by the rotation speed correction means and the opening degree of the intake throttle valve. Item 10. The air flow rate measurement value correction device according to any one of Items 6 to 9.   The air flow rate measurement value correction device according to any one of claims 1 to 10, wherein the correction target air flow rate measurement sensor is a hot wire type air flow meter provided in the intake passage.

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