JPH01155235A - Apparatus for measuring granular substance in exhaust gas - Google Patents

Abstract

PURPOSE:To accurately measure a transient mode, by setting or controlling a control valve so that the detection values of two differential pressure gauges mounted to the first throttle device provided to a passage at the extraction position and the second throttle device provided to an extraction pipe keep predetermined relation. CONSTITUTION:The part of an extraction pipe 13 on the leading end side thereof opened to a dilution tunnel 14 is held to almost atmospheric pressure and the max. exhaust gas flow rate condition of an engine is preset to measure the flow rate of a main flow passage 11 by a differential pressure meter 27. Next, a butterfly valve 33 is adjusted by an actuator 30 to adjust so that the flow rate of the extraction pipe 13 becomes the divided flow rate determined by a cross-sectional area ratio. In this case, since the part of the extraction pipe 13 on the leading end part thereof opened to a dilution tunnel 14 is held to atmospheric pressure, the indication value of the differential pressure meter 28 shows the pressure to the atmosphere at the inlet of an extractor 12. A controller 29 adjusts the butterfly valve 33 through an actuator 30 so as to equalize the difference pressures of the differential pressure meters 27, 28 to adjust the backpressure of the orifice 25 of the main flow passage 11.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application 1 The present invention relates to a device for measuring particulate matter in exhaust gas. This invention relates to a device for measuring particulate matter therein and is suitable for use in measuring exhaust gas from diesel engines.

(Summary of the Invention) The present invention provides a first throttle means and a regulating valve at an extraction position of a passage for exhaust gas discharged from an engine, and
A second throttle means is provided in the extraction pipe connected to the exhaust gas passage, and a second throttle means attached to the first throttle means and the second throttle means is provided.
The adjustment valve is set or controlled so that the detected values of the two differential pressure gauges maintain a predetermined relationship, so that the extraction ratio of exhaust gas extracted through the extraction pipe is always constant. This is what I did.

K. PRIOR ART Exhaust gas from a diesel engine contains particulate matter such as particulates. If such substances are released directly into the atmosphere, they cause air pollution. Therefore, in order to take measures against diesel engine exhaust gas,
Attempts have been made to measure particulate matter contained in exhaust gas.

In this case, the exhaust gas is led to the dilution tunnel, where it is diluted so that the measurement is performed under the same conditions as when the exhaust gas is discharged into the atmosphere. However, if the entire amount of exhaust gas were to be guided into the dilution tunnel, a huge dilution tunnel would be required.
This makes the measuring device very bulky. Therefore, a part of the exhaust gas is separated and extracted, and the extracted gas is diluted using a mini-dilution tunnel, thereby reducing the size of the device.

[Problems to be solved by the invention K] However, the conventional device for measuring particulate matter in exhaust gas using a mini-dilution tunnel was developed for the steady mode, and is not suitable for the transient mode. is not. Therefore, if the state of exhaust gas fluctuates drastically over time, the proportional relationship between the amount of exhaust gas emitted from the engine and the amount of exhaust gas extracted will no longer hold, making it difficult to obtain accurate extraction. This will cause errors in the measurement results.゛The present invention was made in view of these problems, and
It is an object of the present invention to provide a measuring device that allows exhaust gas to be extracted at a constant extraction ratio even when the amount of exhaust gas discharged from an engine changes over time.

Means for Solving Problem K] The present invention extracts a part of the exhaust gas discharged from the engine, guides it to the dilution tunnel, dilutes it in the dilution tunnel, and extracts a part of the exhaust gas discharged from the engine. In an apparatus for measuring a heavy platform by capturing particulate matter from a filter or the like from the exhaust gas passage, a first throttle means and a regulating valve are provided at an extraction position of the exhaust gas passage, and a first throttle means and a regulating valve are provided at an extraction position of the exhaust gas passage, and a first throttle means and a regulating valve are provided at an extraction position of the exhaust gas passage. A second throttling means is provided in the extraction tube, and the detection values of the two differential pressure gauges attached to the first throttling means and the second throttling means maintain a predetermined relationship. 11! so that the detected values are equal to each other! ! It is designed to set or control a valve.

1. Therefore, according to the present invention, by controlling the regulating valve according to the detected values of the two differential pressure gauges, it is possible to maintain the exhaust gas extraction ratio constant at all times, and the amount of exhaust gas discharged is It becomes possible to perform accurate measurements even when the current varies with time, and it becomes possible to perform transient mode measurements with high precision.

K Embodiment 1 FIG. 2 shows an exhaust gas measuring device according to an embodiment of the present invention, in which an exhaust pipe 11 is connected to an exhaust manifold of an engine 10, and this exhaust gas An extractor 12 is connected to the middle of the pipe 11. An extraction tube 13 extending from the extractor 12 is guided into a dilution tunnel 14. The dilution tunnel 14 is for diluting the extracted exhaust gas, and is provided with a filter 15 on its inlet side, and a constant displacement pump 17 consisting of a heat exchanger 16 and a Roots blower on its outlet side. is installed.

Further, a diluted exhaust gas collection pipe 19 and a particulate collection pipe 20 are respectively attached to the dilution tunnel 14.

Next, the structure of the extractor 12 will be explained with reference to FIG. 1. A throttle 25 is provided at the extraction position of the exhaust pipe 11 through which exhaust gas passes. On the other hand, extraction tube 13
is provided with another diaphragm 26. Differential pressure gauges 27 and 28 are connected to both sides of the throttles 25 and 26 of the exhaust pipe 11 and the extraction pipe 13, respectively. These differential pressure gauges 27 and 28 are connected to a controller 29. The output side of the controller 29 is connected to the actuator 30. Actuator 30
The output end of is connected to a lever 32 via a link 31. The lever 32 is the butterfly valve 33 of the discharge pipe 11
The opening and closing of the door is controlled. In addition, the extraction tube 13
A heat retaining means or heating means 34 is provided in the portion of the exhaust pipe 11 that is drawn out to the outside.

In the above configuration, the exhaust gas generated by the engine 10 is discharged to the outside through the exhaust pipe 11, and is extracted at a constant rate by the extractor 12 connected midway through the exhaust pipe 11. The extracted exhaust gas is diluted by the dilution tunnel 14. The dilution tunnel 14 sucks diluted air using a roots blower 17, and the air introduced into the tunnel 14 is first filtered by a filter 15, and then the extracted exhaust gas is diluted.

Then, heat exchange is performed by the heat exchanger 16, and the pump 1
7, so that it is discharged from the tip side.

Then, particulate matter in the exhaust gas is measured based on samples sampled through the diluted exhaust gas collection pipe 19 and the particulate collection pipe 20.

In a device that performs such measurements, the portion on the distal end side of the extraction tube 13 that is open to the dilution tunnel 14 is always maintained at approximately atmospheric pressure. Prior to the test, the maximum exhaust gas flow rate conditions for the engine 10 are set, and the flow rate in the main flow path 11 is measured using the differential pressure gauge 27. Next, the butterfly valve 33 is adjusted by the actuator 30 so that the flow rate of the extraction pipe 13 becomes a divided flow rate determined by the cross-sectional area ratio. In this case, extraction tube 1
3, which is open to the dilution tunnel 14, is maintained at atmospheric pressure, so the reading on the differential pressure gauge 28 indicates the pressure at the inlet of the extractor 12 relative to the atmosphere. . Further, this pressure is also equal to the back pressure of the main flow path 11 up to zero atmospheric discharge.

Therefore, as long as the air resistance of the exhaust gas flow path of the main flow path 11 does not change, even if the flow rate of exhaust gas changes, the back pressure ratio of the main flow path 11 and the extraction flow path 13 will not change, so the division ratio will always remain the same. The cross-sectional area ratio of channels 11 and 13 will be maintained. Note that since the flow rate measuring apertures 25 and 26 are kept under the same temperature condition even if the exhaust gas temperature changes, the differential pressure gauge 27.
The flow rate ratio according to 28 can be accurately measured. Furthermore, since the gas linear velocities in the two flow paths 11 and 13 are always equal, particulates contained in the exhaust gas are also divided at a predetermined division ratio.

In order to achieve such an operation, the detected values of the two differential pressure gauges 27 and 28 are respectively supplied to the controller 29, and the controller 29 adjusts the pressure so that the differential pressures of the two differential pressure gauges 27 and 28 are equal. actuator 3
Adjust the butterfly valve 33 through the main channel 11
The back pressure of the orifice 25 is adjusted. Now, if the flow velocities of the exhaust gas passing through the main flow path 11 and the extraction pipe 13 are V and V, respectively, the following relationship holds true. As described above, the controller 29, actuator 30 and butterfly valve 33
Since control is performed so that ΔP=Δp, the relationship V=V is established. Therefore, the flow rate of exhaust gas in the main flow path 11 and the extraction pipe 13 is proportional to the cross-sectional area ratio, and the extraction ratio is equal to the cross-sectional area ratio.

As described above, the measuring device according to the present embodiment extracts the exhaust gas using the extractor 12 when measuring particulate matter in the exhaust gas discharged from the engine 10, and
The extracted exhaust gas is diluted by a dilution tunnel 14. Therefore, it becomes possible to use a small mini-dilution tunnel 14, contributing to miniaturization of the device. Furthermore, the extractor 12 has throttles 25 and 26 in its main flow path 11 and extraction pipe 13, respectively.
and differential pressure gauges 27 and 28 are provided, and a butterfly valve 33 keeps the extraction ratio constant. Therefore, even if the state of the engine 10 changes, it is possible to always extract exhaust gas at the correct extraction ratio, and
It becomes possible to perform transient mode measurements with high accuracy.

Next, a modification of the above embodiment will be explained with reference to FIGS. 3 and 4. In this modification, a rectifying plate 35 is attached to the upstream side of the connection position of the extraction pipe 13 of the extractor 12.The rectifying plate 35 rectifies the flow of exhaust gas, and then the extraction pipe 13 is connected to the extractor 12. 13. According to such a structure, it is possible to prevent turbulence from occurring in the extraction portion of the extractor 12.

FIG. 5 shows yet another modification, in which the extraction pipe 13 is connected to an opening provided on the side of the exhaust pipe 11 without protruding into the exhaust pipe 11. I'm trying to make it happen.

With this configuration, it is possible to prevent turbulence from occurring in the main flow path 11 due to the extraction pipe 13.

[Effects of the Invention] As described above, the present invention provides a first
A throttling means and a regulating valve are provided, and a second throttling means is provided in the extraction pipe connected to the exhaust gas passage, and two differential pressure gauges attached to the first throttling means and the second throttling means are detected. The regulating valve is set or controlled so that the values maintain a predetermined relationship. Therefore, by setting or controlling this regulating valve, it becomes possible to extract exhaust gas at an extraction ratio that corresponds to the cross-sectional areas of the exhaust gas passage and the extraction pipe, and it becomes possible to accurately measure the transient mode.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing the structure of an extractor of a measuring device according to an embodiment of the present invention, Fig. 2 is a schematic plan view showing the overall structure of the dilution tunnel, and Fig. Figure 3 is a sectional view of the main parts of a modified extractor, and Figure 4 is tV~! in Figure 3. V
FIG. 5 is a longitudinal sectional view of yet another modified example of the extractor. In addition, in the symbols used in the drawings, 10...Engine 11...Exhaust pipe 12...Extractor 13...Extraction pipe 14... Dilution Tunnel 25.26
... Throttle 27,28... Differential pressure gauge 29 ... Controller 30 ... Actuator 33 ... Butterfly valve.

Claims (1)

[Claims] A part of the exhaust gas emitted from the engine is extracted and guided to the dilution tunnel, where it is diluted and particulate matter is captured from the diluted gas and its weight is measured. In the apparatus, a first throttle means and a regulating valve are provided at the extraction position of the exhaust gas passage, and a second throttle means is provided in the extraction pipe connected to the exhaust gas passage, and the first throttle means and the regulating valve are provided at the extraction position of the exhaust gas passage. Measurement of particulate matter in exhaust gas, characterized in that the regulating valve is set or controlled so that detected values of two differential pressure gauges attached to the second throttle means maintain a predetermined relationship. Device.