JPH06341935A - Exhaust gas sampling device for automobile - Google Patents

Abstract

PURPOSE:To provide an exhaust gas sampling device for automobile which can further increase measurement accuracy in the analysis of components of exhaust gas by changing a division ratio of exhaust gas easily in accordance with engines which differ in exhaust air amount from each other and adjusting sampling amount of exhaust gas to be a constant amount. CONSTITUTION:It is an exhaust gas sampling device for automobile in which a multi- pipe type divider 11 consisting of many branch pipes 11a is provided at a downstream end of an exhaust pipe 10 which guides exhaust gas and which guides a part of exhaust gas which passes through the divider 11 into a dilution tunnel 14 via an exhaust gas introduction pipe 12, dilutes the exhaust gas which is guided by dilution gas, and guides a part of the exhaust gas which is diluted, into a component analyzer 20 to analyze the components in the exhaust gas. The multi-pipe type divider 11 is provided with an end face on the inlet side in which each inlet end of many branch pipes is opened, and one of a plural number of diffuser pipes 1, 2, 3 which have different opening are a from each other, cover outer fringe side at the end face on the inlet side of the multi-pipe type divider, and change the number of branch pipes in which exhaust gas flows is selectively provided between the exhaust pipe 10 and the multi- pipe type divider 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle exhaust gas sampling device required for analyzing exhaust gas components discharged from a diesel engine or the like.

[0002]

2. Description of the Related Art An exhaust gas sampling device for automobiles, which is used for analyzing the components of exhaust gas discharged from an engine and samples a part of the exhaust gas, is known to be equipped with a multi-tube split diluting tunnel. . This sampling device is configured, for example, as shown in FIG. That is, at the downstream end of the exhaust pipe 10 that is connected to the tail pipe of an automobile and guides the exhaust gas from the engine, a multi-tube type divider (hereinafter simply referred to as a "divider") that is made up of a bundle of a large number of flow dividing pipes 11a having the same shape. 11) is provided. Then, one of the diversion pipes in the diversion pipe bundle is the exhaust gas introduction pipe 12
Is connected to the dilution tunnel 14 to guide a part of the exhaust gas to the dilution tunnel 14. On the other hand, the other branch pipe 11a guides the remaining exhaust gas to the flue through the surge tank 13.

The dilution tunnel 14 is provided with an exhaust gas introducing pipe 12
The high temperature exhaust gas introduced by the above is uniformly mixed with a clean dilution gas (usually air) to be diluted and cooled. In this tunnel 14, the clean diluent gas that has passed through the filter 16 is fed with a constant flow rate suction device (CVS device) 1
7, the open end 12a of the exhaust gas introduction pipe 12
Mixing orifice 1 provided at an appropriate distance from the downstream side
In part 8, it is mixed with the exhaust gas.

The exhaust gas diluted in this way is sampled by an exhaust gas analyzer 20 equipped with a particulate matter measuring filter 20a and its components are analyzed. Here, in the dilution tunnel 14, in order to analyze the components of the exhaust gas with high accuracy, it is necessary to always keep the division ratio of the exhaust gas divided by the divider 11 constant even if the operating state of the engine changes. .

Therefore, the sampling device usually has a
A division ratio control means is provided, and clean high-pressure air (assist air for pressure control) supplied from an air source through the filter 22 is controlled near the outlet of the exhaust gas introduction pipe 12 while controlling the flow rate of the control valve 24. The outlet static pressure P _S2 is adjusted by ejecting from the disposed injection nozzle 23. The outlet static pressure P _S2 is
It becomes higher as the ejection amount of the assist air ejected from the ejection nozzle 23 increases. On the other hand, the control valve 24 controls the outlet static pressure P _S2 of the exhaust gas introduction pipe 12 and the multiple pipe outlet static pressure P S of the divider 11.
The pressure difference ΔP with _S3 is within a certain allowable range (eg ± 1mm
It is controlled by the control signal from the controller 26 so as to have a value in Aq).

In this way, in the sampling device,
Detecting a differential pressure ΔP between the outlet static pressure P _S2 of the exhaust gas introduction pipe 12 and the multi-pipe outlet static pressure P _S3 of the divider 11, and controlling this differential pressure ΔP to a value within the above-mentioned predetermined allowable range. Keeps the division ratio constant. Incidentally, split ratio, the amount of exhaust gas flowing into the exhaust pipe ^{10 (m 3 / min.)} , An amount of exhaust gas introduced into the dilution tunnel 14 from the exhaust gas inlet pipe 12 (m ³ / min.) The divided value is approximately equal to the number of the flow dividing pipes 11a forming the divider 11.

[0007]

In the above-mentioned exhaust gas sampling apparatus, the split ratio of exhaust gas, that is, the sampling amount of exhaust gas is determined by the number of the flow dividing pipes 11a constituting the divider 11. At this time, in order to improve the measurement accuracy in the exhaust gas component analysis, in the case of an engine with a large displacement, the exhaust gas is also increased accordingly, so the number of the flow dividing pipes 11a is increased to increase the division ratio.
Further, in the case of an engine with a small displacement, the flow dividing pipe 11a
It is necessary to adjust the sampling amount to a constant value according to the engine having a different displacement by reducing the number of lines and the division ratio.

When adjusting the sampling amount of the exhaust gas according to the engine having the different displacement and thus changing the division ratio, conventionally, by exchanging with a divider having a different number of the branch pipes 11a, The sampling amount was adjusted. Therefore, in the replacement of the divider, there is a problem that the replacement work is very complicated, such as connection with the exhaust pipe 10 and the surge tank 13, especially connection between the exhaust gas introduction pipe 12 and the dilution tunnel 14.

The present invention has been made in view of the above points, and the split ratio of exhaust gas can be easily changed according to the engine having different displacement, and the exhaust gas can be adjusted by adjusting the sampling amount of exhaust gas to a constant value. It is an object of the present invention to provide an automobile exhaust gas sampling device capable of further enhancing the measurement accuracy in the component analysis of.

[0010]

According to the present invention, in order to achieve the above object, a multi-tube type divider comprising a large number of flow dividing pipes is arranged at the downstream end of an exhaust pipe for guiding exhaust gas, and the divider is provided. Part of the exhaust gas passing through the exhaust gas is introduced into the dilution tunnel through the exhaust gas introduction pipe, the exhaust gas introduced is diluted with the dilution gas, and part of the diluted exhaust gas is introduced into the component analyzer, In an automobile exhaust gas sampling device for analyzing components, the multi-tubular divider includes an inlet-side end surface at which each inlet end of the plurality of flow dividing pipes is open, and the exhaust pipe and the multi-tubular divider are In between, the opening areas are different, and one of a plurality of intermediate pipes for covering the outer edge side of the inlet side end surface of the multi-tube divider and changing the number of the branch pipes into which the exhaust gas flows is selectively selected. It is configured to be arranged.

[0011]

[Operation] The intermediate pipe arranged between the exhaust pipe and the divider is
Exhaust gas that is divided into exhaust gas introduction pipes by replacing it with one that has an opening area suitable for engines with different displacements and closing a part of the diversion pipe that opens on the inlet side end face of the divider with an intermediate pipe Even if the engines have different displacements, the sampling ratio of the exhaust gas is adjusted to be substantially constant by changing the division ratio of.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. In the following description, the same components as those of the conventional vehicle exhaust gas sampling apparatus described above are designated by the same reference numerals, and detailed description thereof will be omitted. The exhaust gas sampling apparatus for an automobile according to the present invention has a hexagonal cross-sectional shape of the exhaust pipe 10, and the divider 11 also has a hexagonal cross-sectional shape by bundling a large number of flow dividing pipes 11a having a circular cross-section. It is molded, and as shown in FIG. 1, any one of the three diffuser pipes 1, 2 and 3 which are intermediate pipes is selectively disposed between the exhaust pipe 10 and the divider 11. . In FIG. 1, the diffuser pipe 1 is arranged between the exhaust pipe 10 and the divider 11.

FIG. 2 shows the inlet end face of the divider 11.
The inlet ends of the large number of flow dividing pipes 11a are flush with the inlet side end face. The divider 11 shown in the figure has 37 branch tubes 11a at the center surrounded by the innermost hexagonal two-dot chain line (I).
However, in the area surrounded by the hexagonal two-dot chain lines (I) and (II) on the outer side, 24 flow dividing pipes 11a are further surrounded by the two-dot chain line (II) and the solid line (III) on the outer side. 30 flow dividing pipes 1
1a are bundled in the closest packed state, and are configured by a total of 91 flow dividing pipes 11a.

Here, in the divider 11, the gap between the adjacent flow dividing pipes 11a is filled with a filling material such as a synthetic resin, and the exhaust gas is divided into the flow dividing pipes 11. Therefore, the flow dividing pipe 11 is divided.
It does not flow out to the surge tank 13 side downstream through the gap between a. 3 and 4 show an example of the diffuser pipe 1 for a medium-sized engine, for example, an engine having a displacement of 6,000 to 10,000 cc class. The diffuser pipe 1 has connection flanges 1b and 1c having a plurality of bolt holes 1a connected to the exhaust pipe 10 and the divider 11 at the upstream end and the downstream end, respectively.
Is formed and has a hexagonal cross section. The diffuser pipe 1 has an opening 1d of the connection flange 1c at the downstream end.
Are formed in the same hexagonal shape as the region surrounded by the chain double-dashed line (II) in the divider 11,
The exhaust gas from the exhaust pipe 10 flows into these flow dividing pipes 11a surrounded by a total of 61 flow dividing pipes 11a, and at the same time, the connecting flange 1c is provided on the outer edge side of the inlet side end face of the divider 11, that is, The inlet ends of the 30 flow dividing pipes 11a in the region surrounded by the dotted line (II) and the solid line (III) are closed.

As a result, the diffuser pipe 1 has the effect of connecting the medium-sized engine to a suitable divider corresponding to the exhaust amount, and can keep the sampling amount of the exhaust gas substantially constant. Guarantees high measurement accuracy in component analysis. FIG. 5 shows an example of the diffuser pipe 2 used for a large engine, for example, an engine of 10,000 to 22,000 cc class. In the diffuser pipe 2, the opening 2d of the connecting flange 2c at the downstream end has a solid line (III).
Considering the connection with the exhaust pipe 10 having a hexagonal cross section and the exhaust gas shape loss, it is formed in the same hexagonal shape and faces the total of 91 flow dividing pipes 11a surrounded by the solid line (III). Then, as shown in the figure, the pipe wall on the side of the connection flange 2b is formed in a shape that gradually contracts toward the exhaust pipe 10 side.

On the other hand, FIG. 6 shows a small engine, for example, 30
An example of the diffuser pipe 3 used for the 00-6000cc class engine is shown. In the diffuser pipe 3, the opening 3d of the connection flange 3c at the downstream end is formed in the same hexagonal shape as the chain double-dashed line (I), and faces the 37 branch pipes 11a surrounded by the chain double-dashed line (I). In consideration of the connection with the exhaust pipe 10 and the shape loss of the exhaust gas, the pipe wall on the connection flange 3b side is gradually expanded toward the exhaust pipe 10 side.

Therefore, in the case of an engine with a large displacement exceeding 10,000 cc, the diffuser pipe 2 shown in FIG. 5 is used in place of the diffuser pipe 1 shown in FIGS. Set to. At this time, the exhaust gas will flow through all the flow dividing pipes 11a of the divider 11, and the division ratio will be about 91. And the displacement is small 6,
In the case of an engine of 000 cc or less, the split ratio is set small using the diffuser pipe 3 shown in FIG. At this time,
The exhaust gas is surrounded by the chain double-dashed line (I) of the divider 11.
It flows into the branch pipe 11a of the book, and the division ratio becomes about 37.

As described above, in the vehicle exhaust gas sampling apparatus of the present invention, the diffuser pipe 1 (2, 3) can be easily attached to and detached from the exhaust pipe 10 and the divider 11 at the connecting flange portion. Therefore, the diffuser pipes corresponding to various division ratios are prepared in advance, and the exhaust gas division ratios are made variable by exchanging the diffuser pipes according to the displacement of the engine to be applied. The sampling amount of the exhaust gas guided to 14 can be adjusted to be substantially constant, and the measurement accuracy in the exhaust gas component analysis can be further enhanced.

In the above exhaust gas sampling device for automobiles, the case of three kinds of diffuser pipes in which the division ratios are changed to 37, 61 and 91 has been described, but the division ratio is not limited to these. Of course, various split ratios can be used depending on the engine displacement used. Further, in the above embodiment, the diffuser pipe 1 (2, 3) has a hexagonal cross-sectional shape, but it is not limited to the hexagonal shape as long as the division ratio can be kept substantially constant. The shape may be circular.

On the other hand, the divider 11 is composed of a large number of flow dividing pipes 11a having a circular cross section, but it is also possible to use the flow dividing pipes 11a having a hexagonal cross section, in which case a gap is formed between the flow dividing pipes 11a. Therefore, the flow cross-sectional area of the exhaust gas in each of the flow dividing pipes 11a can be maximized. Further, in the above embodiment, if a packing, a gasket or the like is interposed at the connecting flange portion of the diffuser pipe 1 (2, 3) connecting the exhaust pipe 10 and the divider 11, the exhaust gas sealing property is improved. Needless to say.

[0021]

As is apparent from the above description, according to the exhaust gas sampling apparatus for a vehicle of the present invention, the split ratio of exhaust gas can be simplified by exchanging the intermediate pipe according to the engine having different displacement. Since the sampling amount of the exhaust gas can be adjusted to be constant, it is possible to further improve the measurement accuracy in the component analysis of the exhaust gas.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an automobile exhaust gas sampling apparatus of the present invention.

FIG. 2 is an end view showing the arrangement of a large number of diversion tubes on the inlet end surface of the divider.

FIG. 3 is a side view of a diffuser pipe for a medium-sized engine.

FIG. 4 is an end view of the diffuser pipe used in the vehicle exhaust gas sampling apparatus shown in FIG. 1, taken along line IV-IV.

FIG. 5 is a side view of a diffuser tube for a large engine.

FIG. 6 is a side view of a diffuser tube for a small engine.

FIG. 7 is a system configuration diagram of a conventional automobile exhaust gas sampling apparatus.

[Explanation of symbols]

 1,2,3 Diffuser pipe (intermediate pipe) 10 Exhaust pipe 11 Multi-tube type divider 11a Dividing pipe 12 Exhaust gas introduction pipe 14 Dilution tunnel 20 Exhaust gas analyzer

Claims (1)

[Claims] 1. A multi-tubular divider comprising a large number of flow dividing pipes is arranged at a downstream end of an exhaust pipe for guiding exhaust gas, and a part of the exhaust gas passing through the divider is passed through an exhaust gas introducing pipe. In the exhaust gas sampling device for an automobile, which leads to a dilution tunnel, dilutes the introduced exhaust gas with a diluent gas, introduces a part of the diluted exhaust gas into a component analyzer, and analyzes the components in the exhaust gas, the multi-tube type The divider includes an inlet-side end surface where each inlet end of the plurality of branch pipes is open, and the opening areas of the exhaust pipe and the multitubular divider are different from each other, and the multitubular divider is An exhaust gas sampling apparatus for an automobile, characterized in that one of a plurality of intermediate pipes for selectively changing the number of diversion pipes into which the exhaust gas flows is provided so as to cover the outer edge side of the inlet side end surface of the vehicle. .