DE102013108797B4 - EGR device and EGR valve property detector - Google Patents

Abstract

An EGR apparatus for an internal combustion engine (1) having an EGR pipe (41) that circulates an exhaust gas from an exhaust portion of the internal combustion engine to an inlet portion of the internal combustion engine (1), the EGR apparatus having a flow amount of the exhaust gas in the EGR pipe (41), the EGR apparatus comprising: an EGR valve (42) opening or closing a passage of the EGR pipe (41); a differential pressure sensor (43) which detects an EGR differential pressure which is a differential pressure in the EGR pipe (41) between a pressure of the exhaust gas upstream of the EGR valve (42) and a pressure of the exhaust gas downstream of the EGR valve (42) is; a temperature sensor (44) which detects an EGR gas temperature which is a temperature of the exhaust gas in the EGR pipe (41); a first calculation section (S101) that sets a target EGR flow amount that is a target value of the flow amount of the exhaust gas in the EGR pipe (41) based on a rotation speed of the internal combustion engine (1) and a torque of the internal combustion engine (1 ), calculated; a second calculation section (S201) that calculates a target opening area that is a target value of an opening area of the EGR valve (42) based on the EGR differential pressure, the EGR gas temperature, and the target EGR flow amount; a third calculating section (S103) which calculates an opening degree command value based on the target opening area and area-degree characteristic data representing a relationship between the opening area of the EGR valve (42) and an opening degree of the EGR valve (42) to output to the EGR valve (42); a fourth calculating section (S105) that calculates an EGR flow amount that is a flow amount of the exhaust gas in the EGR pipe (41); a fifth calculation section (S106) that calculates an actual opening area of the EGR valve (42) based on the EGR differential pressure, the EGR gas temperature, and the EGR flow rate; ...

Description

The present disclosure relates to an EGR device and a property detector for an EGR valve used in the EGR device. The EGR device controls a flow amount of an exhaust gas circulating from an exhaust portion of an internal combustion engine to an intake portion of the internal combustion engine.

Conventionally, for example, with reference to Japanese Patent Application No. JP 2010-084519 A discloses that an internal combustion engine is provided with an exhaust gas recirculation (EGR) device that circulates exhaust from an exhaust section to an inlet section.

According to the JP 2010-084519 A The EGR device calculates a standard EGR rate based on engine speed and a relationship between engine load and the standard EGR rate. The machine speed and the relationship are pre-stored in a memory. A reference EGR rate is calculated based on a flow amount (EGR flow amount) of an exhaust gas circulating with an intake gas. A correction EGR value is calculated based on the standard EGR rate and the reference EGR rate. A correction EGR opening degree, which is a value for correcting an opening degree of an EGR valve, is calculated based on the correction EGR value. A signal representing the correction EGR opening degree is transmitted to the EGR valve. The EGR flow rate is appropriately set by using the signal through a feedback control of the EGR valve.

According to a formula (1-5) in the JP 2010-084519 A For example, an opening area of the EGR valve is required to calculate the flow amount of the exhaust gas. However, it is difficult to calculate an actual opening area of the EGR valve when the internal combustion engine is in operation. In this case, the opening area is calculated based on an opening degree of the EGR valve and based on data representing an area-degree relationship between the opening area of the EGR valve and the opening degree of the EGR valve ,

However, the range-degree relationship between different EGR valves has variations. Therefore, it is difficult to accurately calculate or control the EGR flow rate.

From the DE 195 02 368 A1 For example, a method of forming a signal with respect to the amount of exhaust gas recirculated in an internal combustion engine is known. The signal for the recirculated exhaust gas amount is formed starting from a signal for the fresh gas flow supplied to the internal combustion engine and a signal for the total of the internal combustion engine supplied gas flow. The signal for the total gas flow supplied is formed from a series of operating parameters. These operating parameters include, among other things, the pressure in the intake tract, which can be detected either by means of a sensor or can be formed from substitute signals. The recirculated exhaust gas quantity signal may be provided with a dynamic correction signal. Furthermore, the signal for the recirculated exhaust gas amount can be used in an exhaust gas recirculation valve with bearing feedback for determining an adaptive correction signal.

From the DE 10 2007 009 698 A1 a method for operating an internal combustion engine with exhaust gas recirculation is known in which air is supplied via an at least partially closable by means of an intake manifold at least one combustion chamber and a portion of the exhaust gases flowing in an exhaust pipe via an EGR valve means at least partially closable EGR Channel is passed into a region of the intake pipe, which is located between the adjusting device and the combustion chamber. In order to provide a method for operating an exhaust gas recirculation internal combustion engine with which a more reliable and lower-emission operation of the internal combustion engine is achieved over the entire service life of the internal combustion engine, it is proposed that a first quantity representing the mass flow of the gas conducted through the EGR channel is determined, is determined from a set of state variables of the internal combustion engine, which apply to an operating state in which the internal combustion engine is in overrun and the actuator is at least substantially closed.

The present disclosure is made in view of the above subject matter, and it is an object of the present disclosure an EGR apparatus to accurately control the EGR flow amount regardless of a variation between different EGR valves, and a characteristic detector for an EGR valve used in the EGR device.

According to one aspect of the present disclosure, an EGR device is mounted on an internal combustion engine having an EGR pipe for circulating an exhaust gas from an exhaust portion of the internal combustion engine to an intake portion of the internal combustion engine. The EGR device controls a flow amount of the exhaust gas circulated through the EGR pipe. The EGR device includes an EGR valve, a differential pressure sensor, a temperature sensor, a first calculating section, a second calculating section, a third calculating section, a fourth calculating section, a fifth calculating section, a sixth calculating section, a seventh calculating section, and a data correcting section.

The EGR valve opens or closes a passage of the EGR pipe. The differential pressure sensor detects an EGR differential pressure which is a differential pressure in the EGR pipe between a pressure of the exhaust gas upstream of the EGR valve and a pressure of the exhaust gas downstream of the EGR valve. The temperature sensor detects an EGR gas temperature, which is a temperature of the exhaust gas in the EGR pipe. The first calculating section calculates a target EGR flow amount that is a target amount of the flow amount of the exhaust gas in the EGR pipe based on a rotational speed of the internal combustion engine and based on a torque of the internal combustion engine. The second calculation section calculates a target opening area that is a target value of an opening area of an EGR valve based on the EGR differential pressure, the EGR gas temperature, and the target EGR flow amount. The third calculating section calculates an opening degree command value to output to the EGR valve based on the target opening area and area-degree characteristic data, and a surface-degree characteristic indicative of a relationship between the opening area of the EGR valve and an opening degree of the EGR valve Represent EGR valve. A fourth calculating section calculates an EGR flow amount which is the flow amount of the exhaust gas in the EGR pipe. The fifth calculation section calculates an actual opening area of the EGR valve based on the EGR differential pressure, the EGR gas temperature, and the EGR flow rate. The sixth calculating section calculates an actual opening degree of the EGR valve based on the area-degree characteristic data and the actual opening area. The seventh calculation section calculates a difference between the opening degree command value and the actual opening degree. The data correction section corrects the area-degree characteristic data based on the difference calculated by the seventh calculation section.

Therefore, since the opening command value of the EGR valve is calculated using the range-degree characteristic data after the correction, the EGR flow amount can be accurately controlled without an effect on the variation of each EGR valve.

Further, even though the area-degree relationship between the opening area of the EGR valve and the opening degree of the EGR valve is varied due to adhesion of deposits in the EGR valve, the area-degree characteristic data becomes each time corrected so that the EGR flow rate can be accurately controlled.

The foregoing and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. It shows / show:

1 12 is a schematic view of an internal combustion engine provided with an EGR device according to a first embodiment of the present disclosure;

2 FIG. 10 is a flowchart showing an EGR control according to the first embodiment, which is executed by an ECU; FIG.

3 FIG. 12 is a graph showing an area-degree relationship between an opening area of the EGR valve and an opening degree of the EGR valve according to the first embodiment; FIG.

4 FIG. 12 is a graph showing a correction example of data representing the range-degree relationship between the opening area of the EGR valve and the opening degree of the EGR valve; FIG.

5 a schematic view of a property detector according to a second embodiment of the present disclosure;

6 FIG. 10 is a flowchart showing a property detection according to the second embodiment, which is executed by an ECU for detecting; FIG. and

7 a graph; which shows an area-degree relationship between the opening degree of the EGR valve and a standard value of the opening area of the EGR valve according to the second embodiment.

Embodiments of the present disclosure will be described below. In the embodiments, a part corresponding to an article described in a previous embodiment may be denoted by the same reference numeral, and a redundant explanation of this part may be omitted. When only a part of a configuration is described in one embodiment, the foregoing embodiment can be applied to the other parts of the configuration. The parts can be combined, even if it is not explicitly described that the parts can be combined. The embodiments may be partially combined, even though it is not explicitly described that the embodiments may be combined, provided that the combination does not cause damage or is detrimental.

Embodiments of the present disclosure will be described with reference to the accompanying drawings. It is noted that similar components of an embodiment of the present description, which are similar to the components of another embodiment, are denoted by the same reference numerals.

First Embodiment

Hereinafter, a first embodiment of the present disclosure will be described.

A body part or housing part 10 an internal combustion engine 1 , what a 1 shown is is with an injector 11 intended. In particular, the internal combustion engine 1 be the type of internal combustion engine with a compression ignition. The injector 11 is connected to a common rail (not shown in detail), which accumulates a fuel under high pressure or accumulates, so that the fuel under high pressure in a combustion chamber 12 is injected. The housing part 10 is with a speed sensor 13 provided, which is a rotational speed of the internal combustion engine 1 detected.

An inlet pipe 20 the internal combustion engine 1 is with an air flow sensor 21 , a throttle valve 22 an inlet pressure sensor 23 , and an inlet temperature sensor 24 intended. The airflow sensor 21 gives an electrical signal corresponding to a mass flow or an amount of air, which into the combustion chamber 12 flows, out. The throttle valve 22 , which downstream of the air quantity sensor 21 is provided opens a passage in the inlet pipe 20 or close this. The inlet pressure sensor 23 , which downstream of the throttle valve 22 is provided, outputs an electrical signal according to a pressure in the inlet pipe 20 out. The inlet temperature sensor 24 , which downstream of the throttle valve 22 is provided, outputs an electrical signal according to a temperature of a gas, which in the combustion chamber 12 flows. In addition, the air flow sensor 21 a sensor with a hot wire.

An exhaust gas pipe or an exhaust pipe of the internal combustion engine 1 is with a catalyst 31 intended. The catalyst 31 is an oxidation catalyst for purifying an exhaust gas by accelerating an oxidation reaction between HC and CO in the exhaust gas. Furthermore, the catalyst 31 collect tiny particles in the exhaust, such as For example carbon.

The internal combustion engine 1 includes an EGR device 40 which controls a flow rate of an EGR gas, which is an exhaust gas circulated from an exhaust gas portion to an intake portion. The flow amount of the EGR gas is referred to as an EGR flow amount. The EGR device 40 includes an EGR tube 41 , The EGR pipe 41 branches from an exhaust gas flow at a position of the exhaust pipe 30 upstream of the catalyst 31 from, and is at a position of the inlet pipe 20 downstream of the throttle valve 22 connected to an inlet gas stream.

The EGR pipe 41 is with an EGR valve 42 providing the EGR flow rate by opening or closing a passage of the EGR tube 41 controls. The EGR valve 42 includes an EGR valve body 420 and an EGR drive section 421 , The EGR body 420 , which is the passage of the EGR pipe 41 by rotation opens or closes, may be a butterfly valve or a throttle. The EGR drive section 421 drives the EGR valve body 420 such that it rotates in accordance with an electric motor.

The EGR pipe 41 is further with a differential pressure sensor 43 , an EGR gas temperature sensor 44 , and an EGR quantity sensor 45 intended. The differential pressure sensor 43 outputs an electric signal according to an EGR differential pressure, which is a differential pressure in the EGR pipe 41 between a pressure of the EGR gas upstream of the EGR valve 42 and a pressure of the EGR gas downstream of the EGR valve 42 is. The EGR gas temperature sensor 44 outputs an electric signal according to an EGR gas temperature, which is a temperature of the EGR gas. The EGR quantity sensor 45 outputs an electric signal according to a mass flow or the EGR flow amount. In addition, the EGR quantity sensor 45 a sensor with a hot wire.

All the output signals of the various sensors mentioned above become an ECU 50 transfer. The ECU 50 includes a microcomputer having a CPU, a ROM, a RAM, and an EEPROM. A specific calculation is made by the ECU 50 based on the output signals performed to the different sections of the internal combustion engine 1 to control. More precisely, the ECU performs 50 an EGR control as described below by controlling an operation of the EGR valve 42 and provides an injection amount of the fuel and an injection time of the fuel by controlling an operation of the injector 11 one.

Referring to 2 , becomes an operation of the EGR device 40 to be discribed.

The ECU 50 starts the EGR control, which is in 2 is shown when the internal combustion engine 1 is started to run, and stops the EGR control when the internal combustion engine 1 not running.

At S101, the ECU calculates 50 a target EGR flow amount Ge which is a target value of the EGR flow amount based on a rotation speed of the internal combustion engine 1 , which by the speed sensor 13 is detected, and based on a torque of the internal combustion engine 1 which is calculated using the injection amount of the fuel. The processing at S101 may correspond to a first calculation section according to the present embodiment.

At S102, the ECU calculates a target opening area Ao which is a target value of an opening area of the EGR valve 42 is, by the formula (1). The processing at S102 may correspond to a second calculation section according to the present embodiment. More specifically, the ECU calculates the target opening area Ao based on the EGR flow amount Ge, which is calculated at S101, the EGR differential pressure Dp generated by the differential pressure sensor 43 is detected, the EGR gas temperature T, which by the EGR gas temperature sensor 44 is detected, and a gas constant C relative to a state of the EGR gas.

At S103, the ECU calculates 50 an opening command value EGRtrg based on the target opening area Ao calculated at S102 and area-degree characteristic data stored in the ECU 50 are pre-stored. Referring to 3 , the range-degree characteristic data represents an area-degree relationship between the opening area Ao of the EGR valve 42 and an opening degree of the EGR valve 42 , The processing at S103 may correspond to a third calculation section according to the present embodiment. Then the ECU gives 50 the opening command value EGRtrg to the EGR valve 42 to set a target opening degree. In addition, the area-degree attribute data in the EEPROM is the ECU 50 saved as an illustration or functional data.

At S104, the ECU determines 50 whether the internal combustion engine 1 in a steady state is in operation. Specifically, when a fluctuation of the rotational speed or a fluctuation of the load of the internal combustion engine 1 is low, such. B. that the internal combustion engine 1 idle, the ECU determines 50 that the internal combustion engine 1 in a steady state is in operation (S104: Yes). Then the ECU leads 50 proceed to step S105. However, if the fluctuation of the rotational speed or the fluctuation of the load is large, the ECU stops 50 the EGR control.

At S105, the ECU calculates 50 an actual EGR flow amount. The processing at S105 may correspond to a fourth calculation section according to the present embodiment. Specifically, the ECU calculates 50 an amount of gas entering the combustion chamber 12 flows based on the rotational speed of the internal combustion engine 1 , the pressure in the inlet pipe 20 , which through the inlet pressure sensor 23 is detected, and a temperature of the gas, which enters the combustion chamber 12 flowing through the inlet temperature sensor 24 is detected. The ECU also calculates 50 the amount of air entering the combustion chamber 12 flows based on an output of the air flow sensor 21 , Then the ECU calculates 50 the actual EGR flow rate subtracting the amount of air entering the combustion chamber 12 flows, from the amount of gas entering the combustion chamber 12 flows.

At S106, the ECU calculates 50 an actual opening area Ao of the EGR valve 42 by the formula (1). The processing at S106 may correspond to a fifth calculation section according to the present embodiment. Specifically, the ECU calculates 50 the actual opening area Ao based on the EGR differential pressure Dp, the EGR gas temperature T, and the goose constant C, and the EGR flow amount Ge calculated at S105. As in the foregoing description, the actual opening area Ao of the EGR valve may be 42 calculated when the internal combustion engine 1 is in operation.

At S107, the ECU calculates 50 an actual opening degree calculation value EGRcal based on the actual opening area Ao calculated at S106 and the area characteristic data stored in the ECU 50 are pre-stored. The processing at S107 may correspond to a sixth calculation section according to the present embodiment.

At S108, the ECU calculates 50 an EGR valve characteristic difference Kdiff by the formula (2). The EGR valve characteristic difference Kdiff is a difference between the opening degree command value EGRtrg calculated at S103 and the actual opening degree calculation value EGRcpal calculated at S107. The processing at S108 may correspond to a seventh calculation section according to the present embodiment. Kdiff = EGRtrg / EGRcal (2)

At S109, the ECU corrects 50 the range-degree characteristic data based on the EGR valve characteristic difference Kdiff calculated at S108, thereby storing the range-degree characteristic data after the correction. The processing at S109 may correspond to a data correction section according to the present embodiment.

More specifically, as in 4 shown, if Kdiff is greater than 1, then the ECU corrects 50 the area-degree characteristic data so that the opening degree becomes a value of a dotted line L1 which is smaller than a respective value of a solid line L2 representing the data which is prestored. If Kdiff is less than 1 then the ECU corrects 50 the range-degree characteristic data so that the opening degree becomes a value of a dot-dashed line L3 which is larger than a corresponding value of the solid line L2.

The range-grade property data after correction may be any EGR valve 42 correspond.

Therefore, since the opening command value of the EGR valve 42 is calculated using the range-grade attribute data after the correction, the EGR flow amount may be devoid of influence of a variation in each EGR valve 42 be controlled exactly.

Further, even though the area-degree relationship between the opening area of the EGR valve 42 and the opening degree of the EGR valve 42 due to adhesion of a deposit to the EGR valve 42 is changed, the area-degree property data is corrected each time so that the EGR flow amount can be accurately controlled. According to the first embodiment, at S105, the actual EGR flow amount may be based on an output of the EGR amount sensor 45 be calculated.

According to the first embodiment, the difference can be stored or corrected as a difference at each opening degree.

Second Embodiment

Hereinafter, a second embodiment of the present disclosure will be described. According to the second embodiment, a characteristic of each EGR valve is detected by a characteristic detector before the EGR valve is mounted in the internal combustion engine. The substantially same parts or components as those in the second embodiment are denoted by the same reference numerals, and the same descriptions thereof will not be repeated.

As well as in 5 is shown, includes the EGR valve 42 a memory 422 which stores difference data as a first storage section.

The property detector includes a blower 60 and an air tube 61 , The fan 60 is powered by an electric motor to create an airflow (it blows air). The air tube 61 guides the blowing air of the blower 60 This is achieved by opening or closing by the EGR valve 42 controlled.

The air tube 61 is with a differential pressure sensor 62 , a blowing temperature sensor 63 and a blown air flow sensor 64 intended. The differential pressure sensor 62 outputs an electric signal according to an EGR differential pressure, which is a differential pressure in the air pipe 61 between a pressure of the blown air upstream of the EGR valve 42 and a pressure of the blown air downstream of the EGR valve 42 is. The blow temperature sensor 63 outputs an electrical signal corresponding to a blown air temperature, which is a temperature of the blown air. The blown air quantity sensor 64 outputs an electric signal corresponding to the amount of blown air, which is a flow amount of the blown air. In addition, the blown air quantity sensor 64 a sensor with a hot wire.

All the outputs of the above various sensors are for detection to an ECU 65 transfer. The ECU 65 for detection includes a microcomputer 650 with a CPU, a ROM, a RAM, and an EEPROM. The ECU 65 The blower controls the detection 60 and the EGR valve 42 and performs a specified calculation based on the output signals, and detects the characteristic of each EGR valve 42 ,

The microcomputer 650 stores standard characteristic data showing a degree-range relationship between the opening degree of the EGR valve 42 and a default opening area value, as in 7 shown. The default opening area value is a default value (design value) of the opening area.

Referring to 6 , an operation of the property detector will be described.

At S201, the ECU selects 65 a default opening degree of a plurality of standard opening degrees for detection, and sets the opening degree of the EGR valve 42 to an opening degree command value according to the selected standard opening degree. The processing at S201 may correspond to a setting section according to the present embodiment. The default opening degrees, for example, are determined in advance to ten levels, and become the microcomputer 650 saved. First, the ECU 65 select the minimum opening degree from the standard opening degrees. Then the ECU 65 in turn, then select a larger opening degree each time the processing is repeated.

At S202, the ECU calculates 65 a standard opening area value Astd based on the standard property data stored in the ECU 65 are stored, and the default opening degree which is selected at S201. The processing at S202 may correspond to a first calculation section according to the present embodiment.

At S203, the ECU records 65 a blown air amount through the blown air flow sensor 64 and sets the blown air amount to a blown air amount Qair according to the standard opening degree selected at S201, to an air blow capacity of the blower 60 adjust. In addition, the amount of blown air is determined in advance for each standard opening degree, and in the microcomputer 650 saved.

At S204, the ECU calculates 65 the EGR differential pressure Dp based on the output of the differential pressure sensor 62 , The ECU also calculates 65 at S204, a blow air temperature Tair based on the output of the blow temperature sensor 63 ,

At S205, the ECU calculates 65 the actual opening area Ao by a formula (3). The processing at S205 may correspond to a second calculation section according to the present embodiment. More specifically, the ECU calculates 65 the actual opening area Ao based on the blown air amount Qair set at S203, the EGR differential pressure Dp calculated at S204, the blown air temperature Tair calculated at S204, and the gas constant Cair relative to a state of the blown air ,

At S206, the ECU calculates 65 an opening area characteristic difference Adiff by a formula (4). The opening area characteristic difference Adiff is a difference between the standard opening area value Astd calculated at S202 and the actual opening area Ao calculated at S205. The processing at S206 may correspond to a third calculation section according to the present embodiment. Adiff = Ao / Astd (4)

At S207, the ECU stores 65 the opening area characteristic difference Adiff in the memory 422 , The processing at S207 may correspond to a differential storage section according to the present embodiment.

The ECU 65 calculates the opening area characteristic difference Adiff in the entire range of the opening degree of the EGR valve 42 by repeating the processing of steps S201 to S207. The ECU 65 stores the opening area characteristic difference Adiff of the EGR valve 42 in the store 422 ,

The EGR valve 42 in which the opening area characteristic difference Adiff in the memory 422 is stored with the ECU 50 the EGR device 40 , which in or on the internal combustion engine 1 attached, connected. Opening area characteristic difference difference data Adiff are sent to the ECU 50 output.

The ECU 50 corrects the area-degree characteristic data based on the opening-area property difference Adiff, thereby storing the area-degree property data after the correction. The ECU 50 calculates the opening degree command value of the EGR valve 40 by the range-grade property data after the correction. Therefore, the EGR flow amount can accurately be without an effect of a variation in each EGR valve 42 be controlled exactly.

Claims (6)

EGR device for an internal combustion engine ( 1 ) with an EGR tube ( 41 ), which is an exhaust gas from an exhaust portion of the internal combustion engine to an inlet portion of the internal combustion engine ( 1 ), wherein the EGR device controls a flow rate of the exhaust gas which is in the EGR tube ( 41 ), wherein the EGR device comprises: an EGR valve ( 42 ), which is a passage of the EGR tube ( 41 ) opens or closes; a differential pressure sensor ( 43 ) which detects an EGR differential pressure which is a differential pressure in the EGR pipe ( 41 ) between a pressure of the exhaust gas upstream of the EGR valve ( 42 ) and a pressure of the exhaust gas downstream of the EGR valve ( 42 ); a temperature sensor ( 44 ), which detects an EGR gas temperature which is a temperature of the exhaust gas in the EGR tube ( 41 ); a first calculation section (S101) that estimates a target EGR flow amount that is a target value of the flow amount of the exhaust gas in the EGR pipe (FIG. 41 ) is based on a rotational speed of the internal combustion engine ( 1 ) and a torque of the internal combustion engine ( 1 ), calculated; a second calculation section (S201) which determines a target opening area which is a target value of an opening area of the EGR valve (FIG. 42 ) is calculated based on the EGR differential pressure, the EGR gas temperature, and the target EGR flow rate; a third calculation section (S103) which displays an opening degree command value based on the target opening area and area-degree characteristic data indicating a relationship between the opening area of the EGR valve (FIG. 42 ) and an opening degree of the EGR valve ( 42 ) to calculate the EGR valve ( 42 ) issue; a fourth calculating section (S105) that calculates an EGR flow amount that includes a flow amount of the exhaust gas in the EGR pipe (FIG. 41 ); a fifth calculating section (S106) having an actual opening area of the EGR valve (S106) 42 ) based on the EGR differential pressure, the EGR gas temperature and the EGR flow rate; a sixth calculating section (S107) that sets an actual opening degree of the EGR valve (FIG. 42 ) is calculated based on the area-degree property data and the actual opening area; a seventh calculation section (S108) that calculates a difference between an opening degree command value and the actual opening degree; and a data correction section (S109) that corrects the area-degree characteristic data based on the difference calculated by the seventh calculation section. An EGR apparatus according to claim 1, wherein said fourth calculating section divides the EGR flow amount by subtracting an amount of air discharged into a combustion chamber (FIG. 12 ) of the internal combustion engine ( 1 ), of an amount of a gas which enters the combustion chamber ( 12 ) flows, calculated. An EGR apparatus according to claim 2, wherein said fourth calculating section determines the amount of gas discharged into the combustion chamber (FIG. 12 ) flows based on a pressure in an intake pipe of the internal combustion engine ( 1 ), the rotational speed of the internal combustion engine ( 1 ) and a temperature of the gas entering the combustion chamber ( 12 ) flows, calculated. An EGR device according to claim 2 or 3, further comprising an air flow sensor ( 21 ), which generates an electrical signal corresponding to an air mass flow through the inlet section of the combustion engine ( 1 ) outputs as an output, the fourth calculating section determining the amount of air entering the combustion chamber ( 12 ) flows based on the output of the air quantity sensor ( 21 ). An EGR device according to claim 1, further comprising: an EGR quantity sensor ( 45 ), which generates an electrical signal corresponding to an EGR mass flow through the EGR tube ( 41 output as an output, wherein the fourth calculating section estimates the EGR flow amount based on the output of the EGR amount sensor (FIG. 45 ). Property detector for an EGR valve ( 42 ) containing an EGR tube ( 41 ) such that it opens or closes it, the EGR tube ( 41 ) an exhaust gas from an exhaust portion of the internal combustion engine ( 1 ) to an inlet portion of the internal combustion engine ( 1 ) and wherein the EGR valve ( 42 ) a first memory section ( 422 ), the property detector for the EGR valve ( 42 ) comprising: a blower ( 60 ), which generates blown air; an air tube ( 61 ), in which the blowing air of the blower through the EGR valve ( 42 ) flows controlled so that it opens or closes a passage of the air tube; a differential pressure sensor ( 62 ), which detects an EGR differential pressure, which is a differential pressure of the air passage between a pressure upstream of the EGR valve ( 42 ) and a pressure downstream of the EGR valve ( 42 ); a temperature sensor ( 63 ) which detects a blown air temperature which is a temperature of the blown air; a blown air quantity sensor ( 64 ) which detects an amount of the blown air, which is a flow amount of the blown air; a second memory section ( 650 ) which stores standard characteristic data indicating a relationship between an opening degree of the EGR valve (FIG. 42 ) and a standard opening area of the EGR valve ( 42 represent); an adjusting portion (S201) that determines the opening degree of the EGR valve (FIG. 42 ) to a default opening degree for detection; a first calculating section (S202) which calculates a standard opening area relative to the standard opening degree for detection based on the standard property data; a second calculating section (S205) having an actual opening area of the EGR valve (S205) 42 ) is calculated based on the EGR differential pressure, the blown air temperature, and the blown air amount; a third calculating section (S206) that calculates a difference between a standard opening area and the actual opening area; and a difference storage section (S207) that stores the difference in the first storage section.

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