JPH06294718A - Exhaust gas sampler for automobile - Google Patents

Abstract

PURPOSE:To sustain a constant gas division ratio by disposing a jet nozzle for pressure control gas closely to the discharge end of an exhaust gas introduction pipe and deflecting the gas flow from the nozzle toward the center of an exhaust gas flow by means of a deflector thereby varying the static pressure at the outlet of the introduction pipe. CONSTITUTION:Four jet nozzles 30 are provided at same interval on the outer periphery at the exhaust end of an exhaust gas introduction pipe 12 in parallel therewith and jet an appropriate quantity of pressure control gas. A deflector 32 is disposed movably in the downstream of the nozzle 30 and in the upstream of a mixing orifice 18 in order to deflect the jet flow from the nozzle 30 toward the center of exhaust gas flow from the introduction pipe 12. The deflector 32 is coupled with a rod 34 and reciprocated by means of a drive motor 36. Upon start of measurement, a controller 38 controls each motor 36 to shift the deflector 32 such that the differential static pressure between the outlet of the introduction pipe 12 and the outlet of multipipe in a divider will be zero. This constitution sustains a constant division ratio of exhaust gas at all times.

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, and more particularly to a split control device for the exhaust gas sampling device.

[0002]

2. Description of the Related Art As an exhaust gas sampling device used for analyzing components of exhaust gas emitted from an automobile engine and sampling a part of the exhaust gas, a device provided with a multi-tube type diversion dilution tunnel is, for example, actually used. Kaihei 5-634
No. 9 publication. This sampling device is configured, for example, as shown in FIG. 1, is connected to a tail pipe of an automobile, and is formed in the middle of an exhaust pipe 10 that guides exhaust gas from an engine, by a plurality of diversion pipes 11a having the same shape. A tube bundle (divider) 11 is provided, and one of the flow dividing tube bundles is connected to a diversion dilution tunnel 14 as an exhaust gas introduction pipe 12, and a part of the exhaust gas is guided to the dilution tunnel 14. The other diversion pipe guides the remaining exhaust gas through the surge tank 13 to the flue.

The diversion dilution tunnel 14 is for uniformly mixing and diluting the exhaust gas guided by the exhaust gas introduction pipe 12 with a clean dilution gas (usually air).
The clean dilution gas that has passed through 6 is a constant flow suction device (CVS
The exhaust gas is guided by the device 17 and is mixed with the diluent gas by the mixing orifice 18 which is arranged at a proper distance downstream from the discharge end 12a of the exhaust gas introduction pipe 12. 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 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 division 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 0. By,
The division ratio is kept constant.

The conventional split ratio control device controls the flow rate of clean high-pressure air (pressure control gas) supplied from an air source through the filter 22 by means of 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 control valve 24 controls the outlet static pressure Ps2 of the exhaust gas introduction pipe 12 and the divider 1
It is controlled by a control signal from the controller 26 so that the differential pressure ΔP with respect to the static multi-pipe outlet static pressure Ps3 of 1 becomes zero.

[0006]

In the analysis of the components of engine exhaust gas, some typical engine operating conditions are selected,
The measurement is performed while sequentially changing the engine operating state to the selected operating state. Whenever the engine operating state changes, it is necessary to adjust the above-mentioned division ratio each time. In this adjustment, since the control valve 24 is arranged at a position away from the injection nozzle, the controller 26 controls the control valve 24. However, there is a problem that the response speed until the amount of the pressure control gas actually ejected from the ejection nozzle 23 changes is slow even if the control signal is output to.

When changing the measurement conditions in the exhaust gas component analysis, it is usually necessary to wait until the newly set engine operating condition becomes stable, and if the waiting time is long, the response speed described above may be somewhat decreased. Even if it is late, there is no problem, but in transient mode measurement where you want to know the exact change in exhaust gas components during transition of engine operating state, the response delay during split ratio adjustment becomes an important issue. .

The present invention has been made in view of the above problems, and provides an exhaust gas sampling apparatus for an automobile, in which the adjustment delay at the time of adjusting the exhaust gas split ratio is minimized to improve the split control accuracy. The purpose is to do.

[0009]

In order to achieve the above object, in the present invention, a multi-tube type divider is arranged in the middle of an exhaust pipe for guiding exhaust gas, and the exhaust gas passing through the divider. Part of the exhaust gas is introduced to the dilution tunnel, the exhaust gas introduced is diluted with the diluent gas, and part of the diluted exhaust gas is introduced to the component analyzer to sample the components in the exhaust gas. In an exhaust gas sampling apparatus for automobiles to be carried out, the discharge end of the exhaust gas introduction pipe is arranged so that its opening faces the downstream side in the diluting gas flow direction in the dilution tunnel, and the vicinity of the discharge end opening of the exhaust gas introduction pipe is provided. At least one injection nozzle that is provided and ejects the pressure control gas, and the flow of the pressure control gas that is ejected from the injection nozzle is directed toward the flow center of the exhaust gas discharged from the exhaust gas introduction pipe. And a driving means for changing the relative positional relationship between the deflecting plate and the injection nozzle so as to keep the division ratio of the exhaust gas divided from the divider into the exhaust gas introducing pipe constant. An exhaust gas sampling device for an automobile is provided.

[0010]

In the exhaust gas sampling apparatus for an automobile of the present invention, the exhaust gas introduction pipe is formed by deflecting the flow direction of the pressure control gas instead of changing the gas amount of the pressure control gas ejected from the injection nozzle. Change the outlet static pressure and adjust the diversion ratio. For this reason, the device of the present invention is provided with a deflection plate, and by changing the relative positional relationship between the deflection plate and the injection nozzle, the flow direction of the pressure control gas ejected from the ejection nozzle is deflected.

As a method of changing the relative positional relationship,
The deflection plate may be moved in the radial direction of the dilution tunnel,
You may make it rotate with respect to an injection nozzle. Further, the deflection plate may be moved in the direction of the central axis of the dilution tunnel.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Incidentally, the vehicle exhaust gas sampling device according to the present invention, the division ratio control device is different from the conventional one,
Since the others may be the same, the same components as those of the conventional device shown in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 2 shows a schematic configuration of a split ratio control device for a vehicle exhaust gas sampling device according to the present invention. The exhaust gas introducing pipe 12 has a predetermined distance from the exhaust pipe 12 at the outer periphery of the exhaust end 12a. Four injection nozzles 30 are arranged at equal intervals on the circumference in parallel with the exhaust gas introducing pipe 12. The injection nozzle 30 is connected to a high-pressure air source, which is a supply source of pressure control gas, through a control valve and a filter (not shown), and the control valve is adjusted to an appropriate amount (constant amount) of pressure control gas. (Assist air)
Are ejected substantially parallel to the flow of the exhaust gas ejected from the exhaust gas introduction pipe 12.

A deflecting plate 32 is arranged at a position downstream of each injection nozzle 30 and upstream of the mixing orifice 18 so as to be movable in the radial direction of the diversion dilution tunnel 14. The deflection plate 32 is attached to a rod 34 described later by inclining a rectangular flat plate with respect to the jet flow from the injection nozzle 30 by a predetermined angle (for example, 45 degrees). The jet is deflected toward the center of the exhaust gas flow in the exhaust gas introduction pipe 12.

The rod 34 extends in an airtight manner to the outside of the diversion and dilution tunnel 14, and a rack is engraved at the extending end thereof. The rack of the rod 34 meshes with the pinion 36a of the drive motor 36, and the rod 3
The deflecting plate 32 connected to 4 can be reciprocated in a predetermined section in the radial direction of the dilution tunnel 14 by the operation of the drive motor 36.

Each drive motor 36 is connected to the output side of the controller 38. A signal corresponding to 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 is supplied to the input side of the controller 36.
Next, the operation of the split ratio control device according to the automobile exhaust gas sampling device of the present invention will be described.
The amount of assist air ejected from the engine is maintained substantially constant during the engine exhaust gas component measurement even if the engine operating state changes. Therefore, the control valve arranged on the upstream side of the injection nozzle 30 does not need to be particularly adjusted during the measurement of the components of the exhaust gas when the assist air amount is set to an appropriate amount. The amount of assist air is adjusted by moving the deflection plate 32 to a position where the rod 34 is most retracted, and
It is preferable that the outlet static pressure Ps2 is set to be slightly lower than the multi-tube outlet static pressure Ps3 of the divider in any engine operating condition.

When the measurement of the exhaust gas component is started, the controller 38 outputs a drive signal to each motor 36 to move the deflection plate 32 to the radial position where the differential pressure ΔP becomes zero. That is, when the outlet static pressure Ps2 of the exhaust gas introduction pipe 12 is lower than the multi-pipe outlet static pressure Ps3 of the divider and the differential pressure ΔP is negative, the rod 34 is pushed in to cause the deflection plate 32 and the injection nozzle 30 to face each other. The deflection plate 32 is moved in the direction in which the positions approach. When the deflecting plate 32 and the injection nozzle 30 approach each other, the assist air is deflected toward a position closer to the outlet of the exhaust gas introducing pipe 12, and accordingly, the outlet static pressure Ps2 of the exhaust gas introducing pipe 12 is increased. Will rise.

On the contrary, the outlet static pressure Ps2 of the exhaust gas introduction pipe 12
Is higher than the multi-tube outlet static pressure Ps3 of the divider and the differential pressure ΔP is positive, the rod 34 is pulled out to move the deflecting plate 32 in the direction in which the relative position between the deflecting plate 32 and the injection nozzle 30 moves away. Good. In this way, by moving the deflecting plate 32 so that the differential pressure ΔP becomes 0, the division ratio of the exhaust gas can always be kept constant. In the above-mentioned embodiment, the deflecting plate is moved so that the differential pressure ΔP is always 0, but it is not always necessary to control the differential pressure ΔP to be 0, and it is predetermined in consideration of various corrections. You may make it control so that it may become a value.

As described above, the method of adjusting the division ratio by moving the deflection plate 32 changes the ejection amount as compared with the conventional method of adjusting the division ratio by opening and closing the control valve to adjust the assist air amount. The responsiveness is quick, as it does not require an invalid time until the assist air is ejected from the control valve through the pipeline.
The exhaust gas component analysis can be accurately performed even when the engine operating state is changed.

In the above embodiment, the injection nozzle 30
Although four are arranged around the outlet of the exhaust gas introduction pipe, the number is not limited to four and may be one, two or six. Further, the injection nozzle 30 is provided with the exhaust gas introduction pipe 1
It does not necessarily have to be arranged in parallel with respect to 2, but may be arranged at an appropriate angle. Furthermore, FIG.
The deflection plate 32 shown in FIG. 3 is a rectangular flat plate, but as shown in FIG. 4, the plate 32A is bent back in an arc shape when viewed in cross section.
May be used, and the shape of the deflection plate is not particularly limited.

Furthermore, in the above-mentioned embodiment, the deflection plate 32 is
Although the rod 34 is reciprocally moved in the radial direction of the diversion dilution tunnel 14 to change the relative positional relationship between the deflection plate and the injection nozzle, the deflection plate is rotated as shown by an arrow in FIG. The relative positional relationship between the deflecting plate and the injection nozzle may be changed, or the dilution tunnel 1
4 may be moved in the direction of the central axis to change the relative positional relationship.

[0022]

As is apparent from the above description, according to the exhaust gas sampling apparatus for an automobile of the present invention, the discharge end of the exhaust gas introduction pipe has its opening downstream in the diluting gas flow direction in the diluting tunnel. At least one injection nozzle for ejecting the pressure control gas is disposed in the vicinity of the discharge end opening of the exhaust gas introduction pipe, and the flow of the pressure control gas ejected from the injection nozzle is discharged. A deflection plate that deflects the exhaust gas discharged from the gas introduction pipe toward the center of the flow, and a deflection plate and an injection nozzle that keep the division ratio of the exhaust gas divided from the divider to the exhaust gas introduction pipe constant. Since the driving means for changing the relative positional relationship is provided, the adjustment delay at the time of adjusting the exhaust gas split ratio can be minimized, and therefore the split control accuracy can be improved. There are excellent effects such as the components change in the exhaust gas during the operation state transition can be measured accurately.

[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 configuration of a division control device of an automobile exhaust gas sampling device of the present invention.

3 is a sectional view taken along the line AA of FIG.

FIG. 4 is a partial cross-sectional view showing a modified example of the deflection plate according to the vehicle exhaust gas sampling apparatus of the present invention.

FIG. 5 is a partial cross-sectional view showing another embodiment of the division control device of the automobile exhaust gas sampling device of the present invention.

[Explanation of symbols]

 12 Exhaust gas introduction pipe 12a Discharge end of exhaust gas introduction pipe 14 Divided dilution tunnel 30 Injection nozzle 32 Deflection plate 32A Deflection plate 36 Drive motor (drive means) 38 Controller (drive means)

Claims (1)

[Claims] 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 that dilutes an exhaust gas with a diluent gas and introduces a part of the diluted exhaust gas into a component analyzer to sample the components in the exhaust gas, the exhaust end of the exhaust gas introduction pipe is , At least one injection nozzle that is arranged so that its opening faces the downstream side in the diluting gas flow direction in the diluting tunnel, is arranged in the vicinity of the discharge end opening of the exhaust gas introduction pipe, and ejects the pressure control gas. A deflection plate for deflecting the flow of the pressure control gas ejected from the injection nozzle toward the flow center of the exhaust gas discharged from the exhaust gas introduction pipe, and the divider divided into the exhaust gas introduction pipe. Automotive exhaust gas sampling apparatus characterized by being configured to split ratio of the exhaust gas and a driving means for changing the relative positional relationship between said deflection plate and the injection nozzle so as to keep constant.