JPH0678848U - Exhaust gas sampling system for automobiles - Google Patents

Abstract

(57) [Summary] [Structure] A diluting tunnel equipped with a multi-tube divider, and a part of the exhaust gas passing through the divider is passed through an exhaust gas introduction pipe 12
In the exhaust gas sampling device for automobiles that conducts sampling of the components in the exhaust gas by leading to 14 and guiding part of the exhaust gas diluted in the dilution tunnel to the component analyzer,
The inner wall of the outlet opening end 12a of the exhaust gas introducing pipe is formed so as to widen toward the outlet so that the apex angle β of the cone formed by the tangent line is 40 ° or more and 90 ° or less. The pressure control gas is ejected by at least one injection nozzle 23 arranged near the opening end, and the division ratio of the exhaust gas divided from the divider into the exhaust gas introduction pipe is kept constant. [Effect] It is possible to suppress the change in the measured value of the inlet pipe outlet static pressure Ps2 due to a processing error of the inner wall shape of the outlet opening end of the exhaust gas inlet pipe as much as possible, and improve the division control accuracy.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an automobile exhaust gas sampling device required for analyzing exhaust gas components emitted from a diesel engine or the like, and more particularly to a division control device for an exhaust gas sampling device.

[0002]

[Prior art]

 An exhaust gas sampling device that is used to analyze the components of the exhaust gas emitted from an automobile engine and samples a part of the exhaust gas is known to be equipped with a multi-tube split flow dilution tunnel. This sampling device is configured, for example, as shown in FIGS. That is, a diversion pipe bundle (divider) 11 composed of a large number of diversion pipes 11 a of the same shape is arranged in the middle of an exhaust pipe 10 that is connected to a tail pipe of an automobile and guides exhaust gas from an engine. One of the diversion pipe bundles is connected to the diversion dilution tunnel 14 as the exhaust gas introduction pipe 12, and a part of the exhaust gas is guided to the dilution tunnel 14, and the other diversion pipes collect the residual exhaust gas. It leads to the flue through the surge tank 13.

The diversion dilution tunnel 14 uniformly mixes the exhaust gas guided by the exhaust gas introduction pipe 12 with a clean dilution gas (usually air), and dilutes the exhaust gas through a filter 16. The gas is guided by a constant flow rate suction device (CVS device) 17, and the exhaust gas is mixed with the diluent gas by a mixing orifice 18 arranged at a proper distance downstream from the outlet opening end 12a of the exhaust gas introduction pipe 12. It The diluted exhaust gas is sampled by the exhaust gas analyzer 20 equipped with the particulate matter measurement filter 20a and the exhaust gas components thereof are analyzed.

In the diversion dilution tunnel 14, it is necessary to always keep the division ratio of the exhaust gas divided by the divider 11 constant even if the engine operating state changes. For this purpose, a split ratio control device is provided, and the differential pressure ΔP between the outlet static pressure Ps2 of the exhaust gas introduction pipe 12 and the multiple pipe outlet static pressure Ps3 of the divider 11 is detected, and this differential pressure ΔP is set to a predetermined value. The division ratio is kept constant by controlling the value within an allowable range (for example, ± 1 mmAq). That is, the split ratio control device controls the flow rate of clean high-pressure air (assist air for pressure control) supplied from the air source through the filter 22 by the control valve 24, and controls this flow rate at the outlet of the exhaust gas introduction pipe 12. The outlet static pressure Ps2 is adjusted by ejecting from the injection nozzle 23 arranged in the vicinity. The injection nozzles 23 are arranged at four equally spaced positions around the outlet opening end 12a of the exhaust gas introduction pipe with an inclination of an angle θ (for example, 45 °) with respect to the introduction pipe 12, and eject from the injection nozzle 23. The outlet static pressure Ps3 increases as the amount of the assist gas ejected increases. The control valve 24 controls the controller 26 so that the differential pressure ΔP between the outlet static pressure Ps2 of the exhaust gas introduction pipe 12 and the multi-pipe outlet static pressure Ps3 of the divider 11 falls within the above-mentioned predetermined allowable range. It is controlled by a control signal.

[0005]

[Problems to be solved by the device]

 As described above, in order to keep the split ratio accurately constant, it is necessary to measure the differential pressure ΔP with high accuracy. However, as a result of various studies by the inventors, the outlet opening end 12a of the exhaust gas introduction pipe 12 is It was found that the shape of the inner wall of No. 1 slightly affects the detection of the differential pressure ΔP. The present invention has been made based on such knowledge, and the change in the measured value of the differential pressure ΔP due to a processing error in the inner wall shape of the outlet opening end of the exhaust gas introduction pipe is suppressed as much as possible to improve the accuracy of division control. It is an object of the present invention to provide a vehicle exhaust gas sampling device.

[0006]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, in the present invention, a multi-tube type divider is arranged in the middle of the exhaust pipe for guiding the exhaust gas, and a part of the exhaust gas passing through the divider is connected to the exhaust gas introducing pipe. In the exhaust gas sampling device for automobiles, which conducts sampling of the components in the exhaust gas by guiding the exhaust gas through the dilution tunnel through the dilution tunnel and diluting the exhaust gas with the dilution gas and guiding part of the diluted exhaust gas to the component analyzer The outlet of the exhaust gas introduction pipe is formed so that the inner wall of the opening end is expanded toward the outlet so that the apex angle of the cone formed by the tangent line is 40 ° or more and 90 ° or less. At least one injection nozzle is provided in the vicinity of the opening end, which ejects the pressure control gas and keeps the division ratio of the exhaust gas divided from the divider to the exhaust gas introduction pipe constant. Cars characterized by An exhaust gas sampling device is provided.

[0007]

[Action]

 As a result of various studies by the inventors of the present application, the inner wall of the outlet opening end of the exhaust gas introduction pipe was expanded toward the outlet so that the apex angle of the cone formed by the tangent line was 40 ° or more and 90 ° or less. When it was formed, it was found that the detected value of the differential pressure ΔP was stable. That is, as long as the inner wall of the outlet opening end is formed so that the apex angle of the cone formed by the tangent line is within the range of 40 ° to 90 °, the processing accuracy of the outlet opening end of the exhaust gas introduction pipe Even if there is some variation, the same detected value of the differential pressure ΔP can be stably obtained, which means that the flow rate control of the assist gas for pressure control is facilitated and the division control accuracy is improved.

[0008]

【Example】

 Embodiments of the present invention will be described below with reference to the accompanying drawings. The exhaust gas sampling apparatus for an automobile according to the present invention is different from the conventional one in the division ratio control device, and the other parts may be the same. Therefore, the same components as those of the conventional device shown in FIGS. The detailed description thereof will be omitted.

FIG. 3 is an enlarged view of the vicinity of the outlet opening end of the exhaust gas introduction pipe 12 of the split ratio control device for the vehicle exhaust gas sampling device according to the present invention. The exhaust gas introduction pipe 12 is, for example, a metal pipe having an inner diameter of 10 mm and a wall thickness of 1 mm, and an adapter 30 is fixed to the outer circumference of the outlet opening end 12 a. The adapter 30 is for fixing the four tubes 32 for measuring the outlet static pressure Ps2 and the four injection nozzles 23 near the outlet opening end 12a. The adapter 30 has a substantially cylindrical shape, and one end surface (end surface on the downstream side of the diluted air flow) 30a is formed in a mortar shape. Then, each injection nozzle 23 forms a predetermined angle θ (for example, 45 °) with respect to the center line of the exhaust gas introduction pipe 12 at a right angle to the end surface 30a of the adapter, and the assist air ejected from the injection nozzle 23 is formed. Are mounted on the center line of the exhaust gas introduction pipe 12 at positions where they collide with each other.

The exhaust gas introducing pipe 12 according to the present invention is characterized by the shape of the inner wall of the outlet opening end 12a thereof, and its details are shown in FIG. That is, the inner wall surface 12c of the end portion of the introduction pipe 12 is formed so as to widen toward the end surface 12b, and the apex angle of the cone formed by the tangent of the inner wall surface 12c (this is referred to as the "inlet pipe outlet angle") β is , 40 ° or more and 90 ° or less. When the outlet angle β is smaller than 40 °, it becomes difficult to process a thin pipe, and when it is larger than 90 °, the static pressure Ps2 of the inlet pipe outlet is largely changed, resulting in poor performance.

FIG. 5 shows the relationship between the inlet pipe outlet angle β and the inlet pipe outlet static pressure Ps2. The graph shown in FIG. 5 shows that the introduction pipe outlet angle β was obtained by changing the introduction pipe outlet angle β while keeping other test conditions such as the assist air amount and the dilution air amount constant except for the introduction pipe outlet angle β. The change amount (mmAq) of the pressure P s2 with respect to the reference value is shown. When the inlet pipe outlet angle β is set to a value of 90 ° or less, the inlet pipe outlet static pressure Ps2 stably shows approximately the same value. That is, when the inlet pipe outlet angle β is set to a value of 90 ° or less, the change in the measured value of the inlet pipe outlet static pressure Ps2 due to the slight difference in the tip shape of the discharge gas inlet pipe 12 becomes small and the split Control of the ratio becomes easy.

[0012]

[Effect of device]

 As is clear from the above description, according to the vehicle exhaust gas sampling apparatus of the present invention, the apex angle of the cone formed by the tangent to the inner wall of the outlet opening end of the exhaust gas introduction pipe is 40 ° or more and 90 ° or more. Since it is formed by expanding it toward the outlet as shown below, it becomes easier to adjust the split ratio, the split control accuracy is improved, and the components of the exhaust gas can be accurately measured. Has an excellent effect.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing a configuration of a conventional automobile exhaust gas sampling apparatus.

FIG. 2 is a partial configuration diagram showing a detailed configuration of a division control device of the automobile exhaust gas sampling device shown in FIG.

FIG. 3 is a partially enlarged cross-sectional view of the vicinity of the outlet opening end of the exhaust gas introduction pipe of the vehicle exhaust gas sampling device according to the present invention.

FIG. 4 is a partially enlarged sectional view of a C circle portion of FIG.

FIG. 5 is a graph showing the relationship between the inlet pipe outlet angle β and the inlet pipe outlet static pressure Ps2.

[Explanation of symbols]

 12 exhaust gas introduction pipe 12a outlet opening end of exhaust gas introduction pipe 14 divided dilution tunnel 18 mixing orifice 23 injection nozzle 30 adapter

Claims (1)

[Scope of utility model registration request] 1. A multi-tubular divider is arranged in the middle of an exhaust pipe for guiding exhaust gas, and a part of the exhaust gas passing through the divider is guided to a dilution tunnel through an exhaust gas introduction pipe and guided. In an automobile exhaust gas sampling device for diluting an exhaust gas with a diluent gas and guiding a part of the diluted exhaust gas to a component analyzer, the exhaust gas sampling device for an automobile, wherein an outlet opening end of the exhaust gas introduction pipe is provided. Inner wall of the exhaust pipe is formed so as to expand toward the outlet so that the apex angle of the cone formed by the tangent line is 40 ° or more and 90 ° or less, and is arranged near the outlet opening end of the exhaust gas introduction pipe to control the pressure. At least 1 for discharging exhaust gas and maintaining a constant split ratio of the exhaust gas split from the splitter to the exhaust gas introduction pipe.
An exhaust gas sampling device for an automobile, characterized in that one injection nozzle is provided.