JP2010139281A - Instrument for measuring exhaust gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas measuring instrument capable of drastically enhancing the reliability of continuous mass emission measurement on the occasion of low emission measurement. <P>SOLUTION: The exhaust gas measurement device 1 measures a B/G concentration when it is determined that the operation of an internal combustion engine stops, and measures the concentration of a diluted exhaust gas when it is determined that the internal combustion engine operates, by using an operation-stop determination means, a means for measuring the concentration of a diluting gas, a means for measuring the concentration of the diluted exhaust gas, and a means for calculating the concentration of an exhaust gas, and performs control to calculate mass emissions on the basis of the measurement results of the B/G concentration and the concentration of the diluted exhaust gas. By doing this way, an influence of variation in the B/G concentration onto continuous mass emission behavior can be suppressed drastically. Accordingly, the reliability of the continuous mass emission measurement on the occasion of the low emission measurement is enhanced drastically. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust gas measuring device.

Conventionally, in order to quantitatively analyze the components contained in the exhaust gas of an internal combustion engine of a vehicle, a continuous mass using CVS (Constant Volume Sampling) that measures the components after the exhaust gas is diluted to a predetermined ratio with a diluent gas Emission measurement is widely performed (see, for example, Patent Document 1).
In the continuous mass emission measurement, in order to improve the measurement accuracy, the component concentration of a dilution gas used for dilution of exhaust gas, so-called background (hereinafter abbreviated as (B / G)) concentration, is measured and measured B A process of performing subtraction calculation (B / G correction) on the measured value of the component concentration in the exhaust gas diluted by the / G concentration is performed. Therefore, a part of the dilution gas is stored in a B / G bag during continuous mass emission measurement, and a value obtained by measuring the component concentration of the stored dilution gas is used as a fixed value of the B / G concentration.
However, since the B / G concentration fluctuates slightly during continuous analysis, using the measured value of the B / G bag as a fixed value of the B / G concentration causes a slight error from the actual B / G concentration. For this reason, a deviation occurs in the B / G correction. Therefore, a slight change in the B / G concentration in real time affects the continuous mass emission behavior, and in particular, a large error occurs in the continuous mass emission measurement value at the time of low emission measurement in HEV (Hybrid Electric Vehicle) or the like. There is a problem such as.

  In order to solve such a problem, even if the flow rate of the dilution gas flowing through the dilution tunnel fluctuates, the B / G concentration measurement is performed by collecting the dilution gas corresponding to the flow rate fluctuation in the B / G bag. Patent Document 2 discloses a technique for improving the reliability.

Japanese Patent No. 3004751 JP 2006-214957 A

  However, in the technique of Patent Document 2, it is difficult to execute B / G correction reflecting a slight change in B / G concentration during continuous mass emission measurement. However, there is a problem that the error of the continuous mass emission measurement value becomes large.

  The present invention has been made in view of such a point, and an object of the present invention is to provide an exhaust gas measuring device capable of greatly improving the reliability of continuous mass emission measurement at the time of low emission measurement.

  In order to achieve the above object, the exhaust gas measuring device of the present invention is configured to dilute the exhaust gas discharged from the internal combustion engine to a predetermined ratio with a dilution gas and supply the diluted exhaust gas to the analysis unit. An exhaust gas measuring apparatus configured, wherein an operation stop determination unit that determines whether or not the operation of the internal combustion engine is stopped, and a determination that the operation of the internal combustion engine is stopped by the operation stop determination unit In the case where it is determined that the internal combustion engine is operating by the dilution gas concentration measuring means for measuring the concentration of the dilution gas and the operation stop determining means, the diluted exhaust gas Based on the measurement results of the diluted exhaust gas concentration measuring means for measuring the concentration, the dilution gas concentration measuring means and the diluted exhaust gas concentration measuring means, the concentration of the exhaust gas discharged from the internal combustion engine Characterized in that it comprises a and an exhaust gas concentration calculating means for calculating.

  According to the exhaust gas measuring device of the present invention, the continuous mass emission measurement can be performed by applying the B / G concentration measured when the internal combustion engine is stopped as the B / G correction value during the subsequent operation of the internal combustion engine. As a result, the fluctuation effect of the B / G concentration on the continuous mass emission behavior can be greatly suppressed. Therefore, the reliability of continuous mass emission measurement at the time of low emission measurement can be greatly improved.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing a schematic configuration of an exhaust gas measuring device 1 of the present invention.

  An exhaust gas measuring apparatus 1 shown in FIG. 1 includes an ECU (Electronic Control Unit) 10 and operates by receiving power supplied through a power supply line, and comprehensively controls the operation of the apparatus. Further, the exhaust gas measuring device 1 includes a dilution tunnel 21 and dilutes the exhaust gas of the internal combustion engine introduced from the exhaust gas introduction pipe 23 to a predetermined concentration. The exhaust gas measuring device 1 includes a CFV (Critical Flow Venturi) 24 and controls the flow rate of the diluted exhaust gas through the dilution tunnel 21 to be constant. Further, the exhaust gas measuring device 1 includes a B / G bag 25 and a sample bag 26, and collects a part of the dilution gas and the diluted exhaust gas, respectively. The exhaust gas measuring device 1 includes a continuous analyzer 27, and analyzes the component concentration of the gas collected by the B / G bag 25 and the sample bag 26 to perform quantitative analysis of the diluted exhaust gas. Execute.

  The dilution tunnel 21 is provided with an exhaust gas introduction pipe 23 in the vicinity of the bottom thereof, and introduces exhaust gas discharged from the vehicle engine into the dilution tunnel 21. In addition, the dilution tunnel 21 is provided with an air filter 22 provided with activated carbon at the inlet of the dilution gas. The air in the laboratory passes through the air filter 22 and enters the dilution tunnel 21, and is mixed with the exhaust gas introduced from the exhaust gas introduction pipe 23, thereby diluting the exhaust gas to a predetermined concentration. The dilution ratio of the exhaust gas is determined by the components contained in the exhaust gas, and is diluted at a ratio that does not cause condensation by adjusting the opening area of the air filter 22. In this case, it is also possible to provide a separate gas cylinder and supply the dilution gas used for dilution of the exhaust gas from the gas cylinder.

  The CFV 24 is provided on the downstream side of the air filter 22 and the exhaust gas introduction pipe 23, and the exhaust gas diluted in the dilution tunnel 21 can be passed by providing a gas passage therein. The CFV 24 is configured such that a partial cross-sectional area of the gas passage is reduced to be smaller than a cross-sectional area of the other part. The exhaust gas diluted in the dilution tunnel 21 is directed to the CFV 24 by driving a blower (not shown) provided downstream of the CFV 24. The flow rate of the gas is controlled to be constant as the gas flow velocity reaches the sea flow velocity (sound velocity at the temperature) by narrowing the flow when passing through the CFV 24. In this case, a venturi flow meter (VFM) capable of continuously changing the flow rate may be provided instead of the CFV 24. The CFV 24 detects the gas volume passing through the CFV 24 and transmits the detection result to the ECU 10.

The B / G bag 25 and the sample bag 26 store gas in the inside thereof by an extendable configuration. The B / G bag 25 is provided on the downstream side of the air filter 22 and on the upstream side of the exhaust gas introduction pipe 23, and collects a part of the dilution gas from a passage communicating with the dilution tunnel 21. The sample bag 26 is provided on the downstream side of the air filter 22 and the exhaust gas introduction pipe 23 and on the upstream side of the CFV 24, and a part of the exhaust gas diluted in the dilution tunnel 21 from a passage communicating with the dilution tunnel 21. Collect. When the gas collection is completed, the B / G bag 25 and the sample bag 26 supply the collected gas to a continuous analyzer 27 described later.
The control valves 31 and 32 are electromagnetic valves provided in the middle of the passages between the dilution tunnel 21 and the B / G bag 25 and between the dilution tunnel 21 and the sample bag 26, and are connected to the B / G bag 25 and the sample bag 26. Adjust the gas flow rate to be taken in. The control valve 31 controls the collection and stop of a part of the dilution gas that has entered from the air filter 22 by opening and closing the electromagnetic valve in accordance with an instruction from the ECU 10. Similarly, the control valve 32 controls the collection and stop of a part of the exhaust gas diluted in the dilution tunnel 21 by opening and closing the electromagnetic valve according to an instruction from the ECU 10. In this case, as the control valves 31 and 32, a three-way valve having one opened to the atmosphere can be used.

The continuous analyzer 27 quantitatively analyzes the gas collected by the B / G bag 25 and the sample bag 26 and transmits the analysis result to the ECU 10. The continuous analyzer 27 is, for example, a non-dispersive infrared absorption meter (NDIR) as a quantitative analysis of CO and CO _2, a hydrogen flame ion detector (HFID) as a quantitative analysis of HC, and a chemiluminescence detector (as a quantitative analysis of NOx). CLD) is applied, but a Fourier transform infrared spectrometer (FTIR) or an automatic gas chromatograph can also be applied.
The continuous analyzer 27 corresponds to the dilution gas concentration measuring means and the diluted exhaust gas concentration measuring means of the present invention.

  The ECU 10 reads the detection result of the CFV 24 and the like, and the analysis result of the continuous analyzer 27, the gas supply operation of the B / G bag 25 and the sample bag 26, the opening / closing operation of the control valves 31 and 32, the opening / closing operation of the air filter 22, The operation of the exhaust gas measuring device 1 such as a purge inside the device is controlled in an integrated manner.

Further, the ECU 10 executes the operation stop determination control for determining whether or not the operation of the vehicle engine is stopped based on the analysis result of the continuous analyzer 27. The ECU 10 determines that the operation of the engine of the vehicle is stopped when the analysis result of the CO ₂ concentration of the continuous analyzer 27 is less than a predetermined value. Here, as the predetermined value of the CO ₂ concentration, a sufficiently small CO ₂ concentration at which it can be determined that the engine is stopped can be applied, and can be set to, for example, 600 [ppm].
In this case, the ECU 10 can also determine whether or not the engine operation of the vehicle is stopped by receiving an engine stop signal directly from the vehicle, or can employ other engine stop determination means. .

When the ECU 10 determines that the operation of the vehicle engine is stopped by the operation stop determination control, the ECU 10 instructs the control valve 32 to be closed and the control valve 31 to be opened, and the B / G bag 25. The dilution gas is stored. Subsequently, the ECU 10 performs dilution gas concentration measurement control for measuring the B / G concentration by supplying the dilution gas stored in the B / G bag 25 to the continuous analyzer 27.
In a low emission measurement test such as HEV, the B / G concentration in the evaluation of intermittently operating the vehicle engine is equal to the continuous analysis value when the engine is stopped. Therefore, by executing the above control, it is possible to greatly suppress the fluctuation effect of the B / G concentration on the continuous mass emission behavior. Therefore, measurement of the B / G concentration C _BG used in the equation (1) described later. The reliability of the value can be greatly improved.

Further, when the ECU 10 determines that the engine of the vehicle is operating by the operation stop determination control, the ECU 10 instructs the control valve 31 to be closed and the control valve 32 to be opened, and the sample bag 26 is diluted with the exhaust gas. Is stored. Subsequently, the ECU 10 executes diluted exhaust gas concentration measurement control for measuring the diluted exhaust gas concentration by supplying the diluted exhaust gas stored in the sample bag 26 to the continuous analyzer 27.
Then, the ECU 10 executes exhaust gas concentration calculation control for calculating the mass emission Mt from the following equations (1) and (2) based on the measurement results of the B / G concentration and the diluted exhaust gas concentration, and the detection results of the CFV 24. .
[Mass emission formula]
Ct = C′t− (1-1 / DFt) × C _BG (1)
Mt = Ct × Vt × component density (2)
(C't: diluting the exhaust gas concentration, DFt: exhaust gas _{dilution, C} BG: B / G concentration, Vt: gas volume)

FIG. 2 shows the mass emission correlation before and after the implementation of the present invention. By implementing the present invention, the B / G correction can be executed based on the highly reliable measurement value of the B / G concentration C _BG , so that the mass emission measurement accuracy is greatly improved over the prior art. Can be made. As described above, since it is possible to perform continuous mass emission measurement that reflects a slight fluctuation in B / G concentration during continuous mass emission measurement, continuous mass emission measurement at the time of low emission measurement such as HEV is performed. The reliability of can be greatly improved.

FIG. 3 shows a hardware configuration of the microcomputer 70 of the ECU 10. The microcomputer 70 includes a CPU 71, ROM 72, RAM 73, NVRAM (Non Volatile RAM) 74, an input / output unit 75, and the like. The CPU 71 reads a program stored in the ROM 72 and performs a calculation according to this program. That is, the CPU 71 reads the program stored in the ROM 72 to control the operation of the apparatus in an integrated manner or to execute exhaust gas concentration calculation control. Further, the RAM 73 is written with data of calculation results such as mass emission calculation, and the NVRAM 74 is the data that has been written in the RAM 73 and data that needs to be saved when the apparatus is turned off. The input / output unit 75 includes a gas volume signal passing through the CFV 24, a gas concentration signal measured by the continuous analyzer 27, a gas storage signal of the B / G bag 25 and the sample bag 26, and a dilution gas flow signal passing through the air filter 22. Input or output signals from various devices.
The ECU 10 corresponds to an operation stop determination unit and an exhaust gas concentration calculation unit of the present invention.

  Next, the operation of the exhaust gas measuring device 1 will be described along the control flow of the ECU 10. FIG. 4 is a flowchart showing an example of processing of the ECU 10. The exhaust gas measuring apparatus 1 of the present embodiment includes an operation stop determination means, a dilution gas concentration measurement means, a diluted exhaust gas concentration measurement means, and an exhaust gas concentration calculation means, so that the operation of the internal combustion engine is stopped. The B / G concentration is measured when it is determined that the engine is operating, the diluted exhaust gas concentration is measured when it is determined that the internal combustion engine is operating, and the measurement results of the B / G concentration and the diluted exhaust gas concentration are measured. Control to calculate mass emission is executed.

  The control of the ECU 10 starts when a request for starting the apparatus is made, that is, when the power is turned on. First, in step S1, the ECU 10 instructs the control valve 31 to be closed and the control valve 32 to be opened, and the diluted exhaust gas passing through the dilution tunnel 21 is stored in the sample bag 26. After finishing the process of step S1, the ECU 10 proceeds to the next step S2.

  In step S2, the ECU 10 supplies the diluted exhaust gas stored in step S1 to the continuous analyzer 27, and starts measuring the diluted exhaust gas concentration C′t. When the ECU 10 finishes step S2, the ECU 10 proceeds to next step S3.

In step S3, the ECU 10 determines whether or not the CO ₂ concentration of the diluted exhaust gas measured in step S2 is less than a predetermined value. Here, since the predetermined value of the CO ₂ concentration has been described above, a detailed description thereof will be omitted. If the CO ₂ concentration is not less than the predetermined value (step S3 / NO), the ECU 10 proceeds to step S5. If the CO ₂ concentration is less than the predetermined value (step S3 / YES), the ECU 10 proceeds to the next step S4.

  In step S4, the ECU 10 determines that the operation of the engine of the vehicle has been stopped, closes the control valve 32, instructs the control valve 31 to open, and supplies the dilution gas that enters from the air filter 22. Store in the B / G bag 25. After finishing the process of step S4, the ECU 10 proceeds to the next step S5.

In step S5, the ECU 10 supplies the dilution gas stored in step S4 to the continuous analyzer 27, and measures the B / G concentration _CBG . By executing this process, the influence of fluctuations in the B / G concentration on the continuous mass emission behavior can be greatly suppressed, so that the reliability of the measured value of the B / G concentration C _BG can be greatly improved. it can. When the ECU 10 finishes the process of step S5, the ECU 10 returns to step S1 and repeats the above process until the CO ₂ concentration reaches a predetermined value or more.

If the determination in step S3 is no, the ECU 10 proceeds to step S6. In step S6, ECU 10, based a dilution exhaust gas concentration C't measured in step S2, and the B / G concentration _{C BG} measured in step S5, the gas volume Vt of CFV24 has detected, the above-described (1 ) The exhaust gas concentration of the vehicle is calculated from the equation (2). In this way, by calculating mass emission based on the measurement value of highly reliable B / G concentration C _BG , the reliability of continuous mass emission measurement at the time of low emission measurement such as HEV is greatly improved. (See FIG. 2). ECU10 complete | finishes the process of control, after finishing the process of step S6.

  As described above, the exhaust gas measuring device according to the present embodiment operates the internal combustion engine by the operation stop determination means, the dilution gas concentration measurement means, the diluted exhaust gas concentration measurement means, and the exhaust gas concentration calculation means. The B / G concentration is measured when it is determined that the engine is stopped, the diluted exhaust gas concentration is measured when it is determined that the internal combustion engine is operating, and the B / G concentration and the diluted exhaust gas concentration are measured. By executing the control for calculating the mass emission based on the measurement result, it is possible to significantly suppress the fluctuation influence of the B / G concentration on the continuous mass emission behavior. Therefore, the reliability of the continuous mass emission measurement value at the time of low emission measurement can be greatly improved.

  The above embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to these, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

It is the block diagram which showed schematic structure of the exhaust-gas measuring apparatus of an Example. The mass emission correlation before and after implementation of the present invention is shown. It is the block diagram which showed the hardware constitutions of the microcomputer of ECU. The flow of control which ECU of an example performs is shown.

Explanation of symbols

1 Exhaust gas measuring device 10 ECU (operation stop judging means, exhaust gas concentration calculating means)
21 Dilution tunnel 22 Air filter 23 Exhaust gas introduction pipe 24 CFV
25 B / G bag 26 Sample bag 27 Continuous analyzer (dilution gas concentration measuring means, diluted exhaust gas concentration measuring means)
31, 32 Control valve 71 CPU
72 ROM
73 RAM
74 NVRAM
75 I / O section

Claims (1)

An exhaust gas measuring apparatus configured to dilute exhaust gas discharged from an internal combustion engine to a predetermined ratio with a dilution gas and supply the diluted exhaust gas to an analysis unit,
An operation stop determining means for determining whether or not the operation of the internal combustion engine is stopped;
A dilution gas concentration measuring means for measuring a concentration of the dilution gas when the operation stop determination means determines that the operation of the internal combustion engine is stopped;
Diluted exhaust gas concentration measuring means for measuring the concentration of the diluted exhaust gas when the internal combustion engine is determined to be operating by the operation stop determining means;
Exhaust gas concentration calculating means for calculating the concentration of exhaust gas discharged from the internal combustion engine based on the measurement results of the dilution gas concentration measuring means and the diluted exhaust gas concentration measuring means;
An exhaust gas measuring device comprising:

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