JPH01302134A - Apparatus for measuring particulate substance in exhaust gas - Google Patents

Abstract

PURPOSE:To enhance not only dividing extraction accuracy but also measuring accuracy, by controlling the pressure in a dilution tunnel so that the extraction ratio of exhaust gas becomes constant. CONSTITUTION:The exhaust gas discharged by an engine 10 is guided to a flow diverter 14 through an exhaust manifold 11 and exhaust pipe 12 and extracted in a definite ratio by the extraction pipe 15 connected to the flow diverter 14 to be diluted in a dilution tunnel 16. The dilution tunnel 16 sucks the air used in the dilution of the exhaust gas by a blower 20 and said air is guided to the tunnel 16 through a filter 17 to be mixed with the exhaust gas extracted through the extraction pipe 15 and the pressure in the tunnel 16 is controlled by a control valve 18 so that the extraction ratio becomes constant. The exhaust gas diluted with the atmosphere is sampled through a diluted exhaust gas sampling tube 30 to be introduced into an analyzer 32 and the particulate substance in the exhaust gas is measured.

Description

[Detailed Description of the Invention] Field of Industrial Application] The present invention relates to a device for measuring particulate matter in exhaust gas, and in particular, to a device for measuring particulate matter in exhaust gas, and in particular to a device for measuring particulate matter in exhaust gas. The present invention relates to a device that dilutes exhaust gas in a dilution tunnel and measures particulate matter contained therein, and is suitable for use in measuring exhaust gas from a diesel engine.

K Summary of the invention] The total amount of exhaust gas discharged from the engine or the Fffi of the extracted residual exhaust gas and the flow rate of the extracted exhaust gas are measured, and the extracted exhaust gas is measured based on these measured values. This system controls the pressure inside the dilution tunnel to dilute the gas, thereby improving the measurement accuracy of exhaust gas and particulates by keeping the split extraction ratio constant. It is.

I. 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 into a dilution tunnel, where it is diluted so that measurements are performed under the same conditions as when the exhaust gas is discharged into the atmosphere. However, if the entire amount of exhaust gas is introduced into the dilution tunnel, a huge dilution tunnel will be required, which will make the measuring device very large. Therefore, a part of the exhaust gas is extracted separately, and the extracted exhaust gas is diluted using a mini-dilution tunnel, thereby reducing the size of the device.

[Problems that KR Ming is trying to solve] When extracting a part of the exhaust gas for measurement in this way, it is recommended to use a porous rectifier tube as proposed in Utility Application No. 15246/1983. The exhaust gas is extracted through one of the many honeycomb-shaped spaces partitioned vertically and horizontally. In such a device, the divided extraction ratio is kept constant by opening the downstream side of the porous rectifier tube to atmospheric pressure.

However, even if the pressure at the open end of the porous rectifier tube and the open end of the extraction tube is kept constant, the pressure at the inlet portion of the porous rectifier tube for performing division changes non-linearly depending on the flow rate of exhaust gas. Therefore, there is a drawback that the division ratio cannot be accurately kept constant. In particular, when the lower end side of the porous rectifier tube is connected to an exhaust pipe having a muffler to apply pressure to the downstream side of the porous rectifier tube, it becomes more difficult to maintain a constant division ratio.

The present invention has been made in view of these problems, and it is an object of the present invention to provide a measuring device that can always obtain a constant split extraction ratio regardless of changes in the flow rate of exhaust gas discharged from an engine. The purpose is to

[Means for Solving the Problems] The present invention extracts a part of the exhaust gas emitted from the engine and guides it to a dilution tunnel, dilutes the exhaust gas in the dilution tunnel, and then dilutes the exhaust gas therein. In the apparatus for measuring particulate matter contained in the engine, there is provided a means for measuring the flow of residual exhaust gas from which all or a part of the engine exhaust gas has been extracted, and a means for measuring Im of the extracted exhaust gas. and means for controlling the pressure in the dilution tunnel for diluting the extracted exhaust gas, the regulating means controlling the pressure in the dilution tunnel such that the extraction ratio is constant. This is how it was done.

1 Effect] Therefore, the flow mountain of the remaining exhaust gas from which all or part of the exhaust gas has been extracted and the flow mountain of the extracted exhaust gas are measured, and the pressure in the dilution tunnel is calculated based on these measured values. By controlling this, it becomes possible to improve the division extraction accuracy and increase the measurement accuracy.

Embodiment K] FIG. 1 shows a particulate matter measuring device according to an embodiment of the present invention, and this device is installed in a diesel engine 1.
This is for measuring particulate matter in the exhaust gas generated. An exhaust manifold 11 is attached to the side of the engine 10, and an exhaust pipe 12 is connected to the tip of the exhaust manifold 11.

The distal end side of the exhaust pipe 12 is connected to a muffler 13, and a branch pipe 14 is connected in the middle of the exhaust pipe 12. An extraction pipe 15 is attached to the branch pipe 14, and the exhaust gas extracted by the extraction pipe 15 is supplied to the dilution tunnel 16.

A filter 1 is installed on the entrance side of the dilution tunnel 16.
7 is provided, and the atmosphere is introduced into the tunnel 16 through this filter 17. A control valve 18 is also provided for controlling the pressure within this tunnel 16. The exit side of the tunnel 16 is connected to a blower 20 via a duct 19. The valve 18 is operated by an actuator 21, and the actuator 21 is controlled by a controller 22.

The extraction pipe 15 is provided with an orifice 25 at its intermediate portion, and is also provided with a flow meter 26 that measures the flow rate based on the pressure on both sides of the orifice 25. An orifice 27 is also provided in the portion of the exhaust pipe 12 between the branch pipe 14 and the muffler 13, and a flow meter 28 is provided to measure the flow rate of exhaust gas from the differential pressure on both sides of the orifice 27. . The output sides of the flow meters 26, 28 are connected to the controller 22.

Further, sampling pipes 29 and 30 are inserted into the above-mentioned branch pipe 14 and dilution tunnel 16, respectively, and these sampling pipes 29 and 30 are connected to a gas analyzer 32 via a switching valve 31. ing. In addition, the above-mentioned branch pipe 1
The pressure on the upstream and downstream sides of the dilution tunnel 16 is detected by pressure gauges 35 and 36, and the pressure inside the dilution tunnel 16 is detected by a pressure gauge 37. and a gas analyzer 32 and three pressure gauges 35
．． 36 and 37 are both connected to the controller 22.

In the above configuration, exhaust gas discharged from the engine 10 is guided to the branch pipe 14 through the exhaust manifold 11 and the exhaust pipe 12. Exhaust gas is extracted at a constant rate by an extraction pipe 15 connected to the branch pipe 14, and the extracted exhaust gas is diluted in a dilution tunnel 16. dilution tunnel 1
Reference numeral 6 uses a blower 20 to suck in air diluted with exhaust gas. This air is introduced into the tunnel 16 through the filter 17 and mixed with the exhaust gas extracted through the extraction pipe 15. The pressure within this tunnel 16 is controlled by a control valve 18. Further, the exhaust gas diluted by the atmosphere is sampled through the diluted exhaust gas sampling pipe 30, and the exhaust gas thus sampled is guided to the analyzer 32 to measure particulate matter in the exhaust gas. That's what I do.

Next, the control of the extraction ratio by the control valve 18 will be explained. In order to keep the divided extraction ratio constant, in this device, the flow rate of exhaust gas is detected by the flow meter 28 from the pressure difference on both sides of the orifice 27. I have to. Further, the flow rate of the exhaust gas extracted by the extraction pipe 15 is detected by a flow meter 26 based on the differential pressure on both sides of the orifice 25. Controller 2 controls these flow rates.
2 is read, the controller 22 performs i-control on the actuator 21 so that a constant division ratio is achieved, and controls the control valve 18 to an optimal opening degree. As a result, the pressure inside the tunnel 16 is adjusted, and the divisional extraction ratio of the flow branch pipe 14 is adjusted accurately, thereby improving the measurement accuracy of exhaust gas and particulates.

At this time, the pressures P+ and Pg on the inlet and outlet sides of the diversion pipe 14 are detected by pressure gauges 35 and 36, respectively, whereas the pressure P3 in the dilution tunnel 16 is It is designed to be detected by a total of 37 people. and these pressures PI, P2
, P3 change as shown in FIG. 2 depending on the flow rate of exhaust gas. Further, the relationship between the opening degree of the control valve 18 to be controlled and the pressure P1 on the inlet side of the branch pipe 14 is as shown in FIG.

In order to ensure the split extraction ratio with higher accuracy, the concentration of the exhaust gas before dilution with the atmosphere is measured, and
The control valve 18 may be controlled so that the division ratio remains constant even if the operating conditions change. The concentration of the exhaust gas before dilution is measured by switching the switching valve 31 to guide the exhaust gas sampled by the sampling pipe 29 to the analyzer 32. Then, the switching valve 31 is switched, and the diluted exhaust gas is transferred from the tunnel 16 to the collection pipe 30.
It is sufficient to collect the sample by using the analyzer 32 and measure it by the analyzer 32.

Note that the response speed of the analyzer 32 is slower than that of the flowmeter 26.28 attached to the orifice 25.27.
It cannot be used when the test mode is transient mode. Therefore, when conducting a transient mode test, first, the opening degree of the control valve 18 is adjusted so that a constant division extraction ratio is achieved in the steady mode, and the correlation with the pressure P1 detected by the pressure gauge 35 is measured. Next, when measuring particulates in the exhaust gas, the pressure P1 is measured by the pressure gauge 35, and the opening degree of the pressure regulating valve 18 is controlled by the actuator 21. Further, since the test mode is constant, the opening degree may be stored for each engine and program control may be performed. Note that the device shown in FIG.
However, the branch pipe 14 may be a single pipe.

[Effects of the Invention] As described above, the present invention measures the flow rate of the remaining exhaust gas from which all or part of the engine exhaust gas has been extracted, and measures the flow rate of the extracted exhaust gas, The pressure inside the dilution tunnel is controlled by a control means such as a control valve using an adjustment means based on the measured value. Therefore, this makes it possible to keep the division extraction ratio constant and improve measurement accuracy.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a particulate matter measuring device according to an embodiment of the present invention, Fig. 2 is a graph showing the relationship between flow rate and pressure, and Fig. 3 is a graph showing the relationship between valve opening and pressure. This is a graph showing. The names of the main parts in the drawings are as follows. 10... Engine 12... Exhaust pipe 14... Diversion pipe 15... Extraction pipe 16... Dilution tunnel 18... Control valve 21... Actuator 22... Controller 25...・Orifice 26...Flowmeter 27φΦΦOrifice 28...Flowmeter 30...Sampling tube 32...Gas analyzer

Claims (1)

[Claims] 1. In an apparatus that extracts a part of exhaust gas discharged from an engine and guides it to a dilution tunnel, dilutes the exhaust gas in the dilution tunnel, and measures particulate matter contained therein. , means for measuring the flow rate of residual exhaust gas from which all or part of the exhaust gas of the engine has been extracted; means for measuring the flow rate of the extracted exhaust gas; and said means for diluting the extracted exhaust gas. In the exhaust gas, the exhaust gas is characterized by being provided with means for controlling the pressure in the dilution tunnel and means for adjusting the means for controlling the pressure in the dilution tunnel so that the extraction ratio is constant. particulate matter measuring device.