JP3030355B2 - Multi-tube type diversion tunnel and its control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention divides a test gas such as an exhaust gas of an engine into a predetermined ratio, further dilutes the divided exhaust gas, and performs a component test such as a concentration of the diluted gas. The present invention relates to a tubular split-flow dilution tunnel and a control device therefor.

[0002]

2. Description of the Related Art For example, in an automobile, in order to take measures to prevent air pollution caused by exhaust gas, it is necessary to collect exhaust gas and analyze and analyze the components of various substances contained therein. However, when a total dilution tunnel is used to analyze and study the components contained in the entire amount of exhaust gas, a large-scale facility is required and a large amount of cost is required. For this reason, it is known to use a small split-flow dilution tunnel to split a part of the exhaust gas and analyze and study the components contained in the exhaust gas divided at a predetermined split ratio. For example, the split-flow dilution tunnel device shown in FIG. 9 includes a multi-tube type splitter 2 composed of a plurality of thin tubes 1 having the same diameter and the same length for exhaust gas from an automobile. It is arranged in the tank 3. The downstream outlet at the other end of the surge tank 3 is configured to discharge exhaust gas to the outside via a flue 17. One of the introduction tubes 4 of the thin tubes 1 in the multi-tube splitter 2 has its downstream end communicated with the dilution tunnel 5. A constant volume suction device 6 is provided at a downstream end of the dilution tunnel 5, and the device 6 sucks outside air from an upstream end of the dilution tunnel 5 through a butterfly valve 24 for adjusting a flow rate. Here, the divided exhaust gas is introduced from the introduction pipe 4 provided immediately before the mixing orifice 7, and the divided exhaust gas is diluted with air as a diluting gas. The diluted divided exhaust gas is obtained by sampling the particulate matter contained in the collected filter 30 and the constant-volume sampling device 41 or by a CO ₂ analyzer 42.

[0003] According to such a split flow dilution tunnel, the split exhaust gas which has been split can be introduced into the dilution tunnel by the action of the introduction pipe 4 at a ratio of the number of the introduction pipes.
After the divided exhaust gas is diluted with dilution air, the diluted gas can be sampled and a component test can be performed. By the way, in such a device, due to the relationship of the fluctuation of the pressure loss of the multi-tube splitter 2 due to the fluctuation of the engine output,
The division ratio of the divided exhaust gas flow rate introduced into the dilution tunnel via the introduction pipe 4 to the total exhaust gas flow rate is likely to fluctuate.
Therefore, a nozzle (see FIG. 2) for ejecting clean high-pressure air is provided at the outlet of the introduction pipe 4, and a pressure adjusting device for adjusting the introduction pipe exit pressure Ps2 using the dynamic pressure of the injection air of the nozzle is provided. That is being done. Thereby, the inlet pipe outlet pressure Ps on the dilution tunnel side in the multi-tube splitter 2
2 and the bypass pipe outlet pressure Ps3 on the side of the surge tank 3 is controlled so that the exhaust gas can be split at the split ratio of the multi-tube splitter 2.

[0004]

In order for such a multi-tube split-flow dilution tunnel to have the same measurement accuracy as that of a full-volume dilution tunnel, the exhaust gas must be reduced by the multi-tube splitter even when the operating conditions fluctuate. It must be guided into the dilution tunnel with a split ratio of two. However, in practice, the flow path resistance of each pipeline easily fluctuates in accordance with the variation of the operation state, and the suction system of the piping system at the outlet of the surge tank 3 and the chimney 17 differs from bench to bench. Therefore , introduction of the dilution tunnel side
Pipe outlet pressure Ps2 and bypass pipe outlet on surge tank 3 side
Only the control for reducing the pressure difference from the pressure Ps3 to zero could keep the variation width of the division ratio between the operation modes to within about ± 5%.

As shown in FIG. 6, the differential pressure Δp (= Ps2−Ps) of the domestic 13 mode average CO ₂ exhaust gas split ratio
3) The first example of the variation (%) in the zero control is shown by a broken line of-△-, and the second example is shown by a broken line of ... △. As is clear from this diagram, the variation range is within ± 5%, but the CO ₂ exhaust gas split ratio greatly fluctuated in each mode. For this reason, it has not been possible to accurately divide the exhaust gas into set values irrespective of the fluctuation of each operation state, thereby performing a highly accurate component test.
An object of the present invention is that, firstly, regardless of fluctuations in the operating state of each engine, exhaust gas that has been accurately split at a target split ratio is always introduced into a dilution tunnel, and an exhaust gas component test can be performed accurately. It is an object of the present invention to provide a multi-tube split-flow dilution tunnel which can be performed and a control method thereof.

[0006]

In order to achieve the above-mentioned object, a first aspect of the present invention is to provide a method for diluting a divided exhaust gas into a diluted tunnel.
The introduction pipe to be introduced into the pipe and the introduction pipe and many bypass pipes
And a splitter that splits the exhaust gas of the engine.
A high-pressure air outlet opening in the vicinity of the introduction pipe outlet in the dilution tunnel; and a multi-purpose exhaust gas measuring engine for controlling air supplied from the high-pressure air outlet to control the pressure at the introduction pipe outlet. In the pipe type diluting tunnel, before the exhaust gas measurement, the above-mentioned bypass pipe exits for each operation mode of the engine at the set exhaust gas split ratio.
Measure the optimum differential pressure value between the inlet pressure and the inlet pipe outlet pressure, and measure the bypass pipe in each operation mode when measuring exhaust gas.
The air supplied from the high-pressure air outlet is controlled so that the differential pressure between the outlet pressure and the inlet pipe outlet pressure becomes the optimum differential pressure value in each of the operation modes. The first invention is characterized in that the engine intake air amount and the fuel flow rate in each operation mode are measured at the time of measuring the optimum differential pressure value, and the operation mode is determined based on the intake air amount and the fuel flow rate at the time of exhaust gas measurement. It is good.

The second invention dilutes the divided exhaust gas.
The introduction pipe to be introduced into the tunnel, and the introduction pipe and a large number of bypass pipes
Divider that splits engine exhaust gas
When the high pressure air outlet opening to the inlet tube near the outlet in the dilution tunnel, out the outlet pressure and the inlet pipe of the bypass pipe in each operation mode when the exhaust gas measurement
Control for controlling the air supplied from the high-pressure air outlet so as to optimize differential pressure value (differential pressure value should be set division ratio) in each operation mode of the differential pressure value measured in advance and mouth pressure Means. The second invention has, in particular, an intake air amount detecting means for detecting an intake air amount of the engine, and a fuel flow rate detecting means for detecting a fuel flow rate,
It may be characterized in that at the time of exhaust gas measurement, the number of operation modes is determined based on the intake air amount and the fuel flow rate.

[0008]

[Action] A first aspect of the present invention, prior to the exhaust gas measurement, the bypass pipe outlet pressure and inlet tube outlet pressure of each operating mode of the engine to be used in the exhaust gas test in the exhaust gas divided ratio set
Measure the optimal differential pressure value of the force , and measure the exhaust pipe pressure and bypass pipe outlet pressure in each operation mode when measuring exhaust gas.
Since the air supplied from the high-pressure air outlet is controlled so that the pressure differential pressure becomes the optimum differential pressure value in each operation mode, the division ratio of the exhaust gas in each operation mode can be accurately controlled to the target value. In particular, by measuring the intake air amount and the fuel flow rate of the engine at the time of measuring the optimum differential pressure value, and determining the operation mode according to the same value at the time of measuring the exhaust gas,
If the operation modes are switched, the split ratio control of the exhaust gas after the operation modes are reliably reached can be performed with high accuracy.

According to a second aspect of the present invention, the control means controls the outlet pressure and the introduction pressure of the bypass pipe in each operation mode in the exhaust gas measurement.
Since the air supplied from the high-pressure air outlet is controlled so that the differential pressure value from the pipe outlet pressure becomes the optimum differential pressure value (differential pressure value that should become the set split ratio) in each operation mode measured in advance, It is possible to control the split ratio of the exhaust gas in each operation mode to the target value with high accuracy. The second invention, in particular,
At the time of the exhaust gas test, if the operation mode is determined based on the intake air amount and the fuel flow rate by the intake air amount detection means and the fuel flow rate detection means, the exhaust gas split ratio control after reaching each operation mode without fail. Can be performed with high accuracy.

[0010]

FIG. 1 shows a multitubular split-flow dilution tunnel as one embodiment of the present invention. In FIG. 1, a multi-tube split-flow dilution tunnel controls the exhaust gas of an engine 10 by an exhaust gas pipe 1.
Through 1, a plurality of thin tubes having the same diameter and the same length are guided to a multi-tube type splitter 12 formed by bundling. One of the thin tubes of the multi-tube splitter 12 is extended and provided as an inlet tube 13 in the dilution tunnel 15, and the downstream end of the other narrow tube 14 on the bypass side is connected to the surge tank 1.
6 has been introduced. The downstream opening of the surge tank 16 is once opened to the atmosphere, and then communicates with the flue 17 via a pressure regulating valve 18. The dilution tunnel 15 is equipped with a constant volume suction device (CVS) 24 at a downstream end thereof so as to suck outside air from an upstream end thereof through an ambient filter 19 and a butterfly valve 20 for adjusting a flow rate. A mixing orifice 21 is provided at an intermediate portion of the dilution tunnel 15 and dilutes the divided exhaust gas introduced from the introduction pipe 13 immediately before the mixing orifice 21 with air which is a dilution gas. Further, on the downstream side of the dilution tunnel 15, a constant volume sampling device 22 for sampling the diluted gas, or a CO ₂ analyzer 2
3 are deployed.

The downstream end of the introduction pipe 13 is provided to face the mixing orifice 21 of the dilution tunnel 15, and a split ratio control nozzle 25 is provided at the downstream end thereof. A pressure control device 27 is connected to the division ratio control nozzle 25 via an ejection amount control valve 26 for increasing and decreasing the ejection amount of the control nozzle. A pressure control device 27 as the ejection amount control valve 26
An electropneumatic converter for increasing or decreasing the pressure value of the supply air in accordance with the electric signal Du from the controller is connected to a high-pressure air tank (not shown) connected to the ejection amount control valve 26 so that high-pressure air is supplied from the tank. It is composed of A static pressure detector 36 that outputs a pressure P4 signal of the high-pressure dilution gas to the pressure control device 27 and a controller 37 described below is provided upstream of the division ratio control nozzle 25. Split ratio control nozzle 25
As shown in FIG. 2 and FIG.
1, the outer end of which passes through the dilution tunnel 15, and the outer end merges and communicates with the ejection amount control valve 26 side.
Here, the single nozzles 251 are provided with eight inner diameters of about 3 mm, and each single nozzle 251 is arranged such that its center line 11 and the outlet center line 12 of the outlet of the introduction pipe 13 face each other at an intersection angle θ. Has been established.

For this reason, the individual nozzles 251 facing each other about the outlet center line 12 are axially symmetrical with respect to the introduction pipe 1.
3, the outlet static pressure Ps2 of the introduction pipe can be adjusted according to the dynamic pressure of the high-pressure air when the high-pressure air is ejected. A static pressure detector 34 is provided on the upstream side of the outlet end of the introduction pipe 13 beyond the inner diameter d of the pipe, and reduces pressure fluctuations due to pulsating flow and the like to reduce the introduction pipe exit pressure Ps of the introduction pipe 13.
2 is detected and input to the pressure control device 27. In addition,
Bypass tube outlet pressure of bypass side thin tube 14 of multi-tube type divider
The Power Ps3 has also been issued RIKEN by the static pressure detector 35 in the same manner. The outlet static pressure Ps2 of the inlet pipe 13 and the multi-tube splitter
The bypass pipe outlet pressure Ps3 is transmitted from the pressure control device 27 to the controller 37 at an appropriate time. Further, the pressure control device 27 comprises a well-known electronic control circuit,
Exchanges signals with the other side, takes in the target value Δp in a timely manner,
Current inlet pipe outlet pressure Ps2 and bypass pipe outlet pressure Ps3
Is output to the ejection amount control valve 26 such that the difference Δpn with the target value Δp coincides with the target value Δp.

When the pressure control device 27 adjusts the high-pressure dilution gas pressure P4 by the ejection amount control valve 26 after the parameters of the split ratio control nozzle of FIG. 1 are set as described above, as shown in FIG. Inlet pipe outlet pressure Ps2 and bypass
Control is performed by using a map in accordance with the change characteristic of the pipe outlet pressure Ps3. In this case, in particular, since the inlet tube outlet pressure Ps2 against high dilution gas pressure P4 varies substantially linearly, introduction tube outlet pressure Ps2 and bypass
It becomes easy to control so that the difference Δpn of the pipe outlet pressure Ps3 matches the target value Δp. The dilution tunnel 15 is provided with a background CO ₂ analyzer 28 at a position upstream of the butterfly valve 20, and the exhaust gas pipe 11 is provided with a direct CO ₂ analyzer 29.
In the test engine 10, a laminar flow meter 31 for detecting an intake air amount Qa is connected to an intake pipe 30, and a fuel flow meter 33 is provided in the middle of a fuel supply system 32 of the engine.

The main part of the controller 37 is constituted by a microcomputer, and a storage circuit (not shown) stores a control program as shown in FIG. 8 and an operation mode discrimination map used in the 13 mode table operation as shown in Table 1. It is stored. The controller 37 controls the operation modes of the engine used in the exhaust gas measurement (for example, 13 domestic modes, etc.) so that a predetermined exhaust gas split ratio SR (for example, the number ratio of multiple tubes 37) is obtained between the operation modes. Pipe outlet pressure Ps3 for each bypass pipe and the inlet pipe
The optimum differential pressure Δp value of the outlet pressure Ps2 and each data of the intake air amount Ga and the fuel flow rate Gf of the engine are obtained.
Step-up condition data Gf which is upper / lower limit data of allowable ranges of the inlet pipe outlet pressure Ps2 and the bypass pipe outlet pressure Ps3.
s and Gas are also obtained by learning driving, and an operation mode determination map as shown in Table 1 is created.

In addition, in the actual exhaust gas measurement, the controller 37 functions as a control means, and controls the split ratio control so as to obtain the optimum differential pressure Δp value that can achieve the set split ratio 37 in each of the previously measured operation modes. The high pressure air pressure P4 supplied from the nozzle 25 is controlled.

[0016]

[Table 1]

In preparing the operation mode determination map shown in Table 1, the lever opening θ of the fuel injection pump (not shown) of the engine 10 and the engine speed Ne are sequentially changed to operate the engine 10 in a predetermined operation mode. Operate sequentially. At that time, the controller 37 obtains the diluted exhaust gas CO ₂ concentration from the output of the CO ₂ analyzer 23 (TCO _2%), C
Background C of dilution air from output of O ₂ analyzer 28
O seek ₂ concentration (BCO _2%), determined directly exhaust gas CO ₂ concentration in the exhaust gas from the output of the CO ₂ analyzer 29 _(2% DCO), the intake air amount of the intake pipe 30 from the output of the lamina flowmeter 31 Obtain Qa (m ³ / min at 0 ° C./760 mmHg)
From the output of the sensor in the constant volume suction device (CVS) 24, the mini-tunnel CVS flow rate Vmix (m ³ / min at 0 ° C / 760)
mmHg), and the gas flow rate Qf (m ³ / min at 0 ° C.) generated by combustion of the fuel according to the fuel flow rate Gf
760 mmHg), and calculate the CO ₂ exhaust gas split ratio SR according to the equation (1).

[0018]

(Equation 1)

[0019] Here, DK _W direct emission Dry-Wet correction factor, TK _W direct emission Dry-Wet correction factor, BK _W background Dry-Wet correction factor indicates, each value is appropriately set. The target value of the CO ₂ exhaust gas split ratio SR is set to 37 here, and the split ratio based on the actual data obtained according to the equation (1) in each mode among the data collected by the inventor is shown in FIG. 5, the variation% with respect to the mode average CO ₂ exhaust gas split ratio at that time is shown in FIG. 6, and the optimum differential pressure Δp value is shown in FIG. ). Then, based on these actually measured values, FIG.
The split ratio SR (here, 3
7) Optimal differential pressure Δp and inlet pipe outlet pressure P for achieving
Step-up condition data Gfs and Gas, which are upper and lower limit data of the allowable range of s2 and bypass pipe outlet pressure Ps3, are collected for each operation mode range of the intake air amount Ga and the fuel flow rate Gf in each operation mode. Based on this, an operation mode discrimination map as shown in Table 1 was created here.

A control method using such a multi-tube split flow dilution tunnel will be described along with the operation of the controller 37 and the control flow of FIG. First, the engine 10 is warmed up, and the operation at the engine speed Ne and the lever opening θ _L (load) in the first mode is maintained. In this case, the controller 37 takes in the intake air amount Ga and the fuel flow rate Gf of the engine 10 in steps s1 and s2.
It is determined which mode in the operation mode discrimination map is within the range of the step-up condition data Gfs and Gas. If the mode is out of the range, the process returns to step s1. Proceed to step s4. In step s4, it is determined whether or not a predetermined determination time Twa has elapsed, and the process proceeds to step s5 before and during counting,
The Twa counter is driven. If the process proceeds to steps s7, s8, and s9 during the continuation of the count, the optimum differential pressure Δp in the set mode (for example, mode 1) is called in accordance with the operation mode determination map in Table 1 and the same value is set as the pressure. It is output as a voltage value to the control device 27, performs a CO ₂ concentration data collection process, and waits for the determination time Twa to elapse.

That is, during this time, the pressure control device 27 side is provided with the latest inlet pipe outlet pressure Ps2 and the bypass pipe of the multi-tube type splitter.
The present differential pressure Δpn is detected based on the outlet pressure Ps3, and if the differential pressure value is different from the acquired optimal differential pressure Δp by δ, δ is corrected to correct the current differential pressure Δpn to the optimal differential pressure Δp. Is output to the ejection amount control valve 26, whereby the split ratio control nozzle 25 ejects high-pressure air and the introduction pipe outlet pressure Ps by the dynamic pressure of the air.
2 can be controlled so as to secure the optimum differential pressure Δp. The controller 37 performs a CO ₂ concentration data collection process during the securing of such an optimum differential pressure Δp. That is, the controller 37 calculates the concentration of the diluted exhaust gas CO ₂ (TCO ₂ %) from the output of the concentration CO ₂ analyzer 23, and obtains the CO ₂ analyzer 2
8, the background CO ₂ concentration (B
CO ₂ %), the concentration of CO ₂ in the exhaust gas in mode 1 of the engine 10 is analyzed, and a predetermined storage process is performed.

The CO in the exhaust gas in mode 1 as described above
_{When the} processing for obtaining the density of ₂ is completed after the elapse of the determination time Twa, the process proceeds from step s4 to step s6, and in step s6, a command is issued to the pressure control device 27 side to hold the pressure control in a waiting state. In this case, the pressure control device 27 continues the PID control so as to maintain the previously set indicated differential pressure Δp in mode 1, and returns to step s1.

Eventually, the driver or the engine automatically switches to operation with the engine operating range Ne and the lever opening θ _L (load) according to the second mode as the next setting mode in the operation range of the engine, The operation state of the engine 10 is switched to the second mode. When this mode switching process is performed, the controller 37 takes in the intake air amount Ga and the fuel flow rate Gf of the engine again in step s1, and these values are used as the values of the step-up condition data Gfs and Gas in the operation mode determination map of Table 1. It is determined that the mode is within the range in mode 2, and if it is, the process proceeds to step s3 again,
Is set, and the processing of step s4 and subsequent steps is executed so as to conform to mode 2. Also in this case, the controller 37 analyzes the concentration of CO ₂ in the exhaust gas in the mode 2 and performs a predetermined storage process while the determination time Twa continues. In the above, the exhaust gas has been described as the exhaust gas when the engine for the vehicle is driven, but it is also necessary to analyze and study the exhaust gas of other various engines and the components of various gases emitted by devices other than the engine. The multi-tube split-flow dilution tunnel and the control method thereof according to the present invention can be used.

[0024]

As described above, according to the first aspect of the present invention, before measuring the exhaust gas, the optimum differential pressure value for each operation mode capable of achieving the set exhaust gas split ratio is measured. Since the air supplied from the high-pressure air outlet is controlled so that the optimum differential pressure value in each operation mode is secured during the exhaust test, the division ratio of the exhaust gas in each operation mode is accurately divided. As a result, a highly accurate component test of the exhaust gas can be performed. The first invention particularly measures the intake air amount and the fuel flow rate of the engine at the time of measuring the optimal differential pressure value, reliably determines the operation mode according to the same value at the time of measuring the exhaust gas, and detects the exhaust gas in each operation mode. The division ratio control can be performed with high accuracy, and thereby a highly accurate component test of the exhaust gas can be performed.

According to a second aspect of the present invention, the differential pressure between the outlet pressure of the bypass pipe and the outlet pressure of the inlet pipe in each operation mode is supplied from the high-pressure air outlet so that the differential pressure value becomes a previously measured optimum differential pressure value. By controlling the air to be blown, the division ratio of the exhaust gas in each operation mode can be accurately controlled to a target value, thereby performing a highly accurate component test of the exhaust gas. The third invention is particularly useful when measuring exhaust gas.
Since the operation mode is determined based on the intake air amount and the fuel flow rate, it is possible to reliably determine that each operation mode has been reached, thereby performing a highly accurate component test of the exhaust gas.

[Brief description of the drawings]

FIG. 1 is a schematic overall configuration diagram of a multitubular split-flow dilution tunnel as one embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a split ratio control nozzle used in the multi-tube split-flow dilution tunnel shown in FIG. 1;

FIG. 3 is a schematic front view of a split ratio control nozzle used in the multi-tube split flow dilution tunnel of FIG. 1;

FIG. 4 is a control characteristic diagram of an optimum differential pressure Δp of a split ratio control nozzle used in the multi-tube split flow dilution tunnel of FIG. 1;

FIG. 5 is a characteristic diagram showing division ratio data of CO ₂ exhaust gas from the engine of FIG. 1 in each mode.

FIG. 6 is a characteristic diagram showing the variation of the split ratio data of the CO ₂ exhaust gas from the engine of FIG. 1 with respect to the mode average value.

FIG. 7 is a characteristic diagram showing an optimum differential pressure value Δp along each mode when data of a split ratio of CO ₂ exhaust gas from the engine of FIG. 1 is collected.

FIG. 8 is a flowchart of control performed by a controller used in the multitubular split-flow dilution tunnel of FIG. 1;

FIG. 9 is a schematic configuration diagram of a conventional device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Engine 11 Exhaust pipe 12 Multi-tube type splitter 13 Inlet pipe 15 Dilution tunnel 16 Surge tank 18 Flue 19 Ambient filter 23 CO ₂ analyzer 25 Split ratio control nozzle 26 Ejection amount control valve 28 CO ₂ analyzer 29 CO ₂ analysis Total 31 Lamina flow meter 33 Fuel flow meter

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuhiko Nara 5-33-8 Shiba, Minato-ku, Tokyo / Inside Mitsubishi Motors Corporation (72) Inventor Mitsunobu Sekiya 2-4-2 Nishishinjuku, Shinjuku-ku, Tokyo No. 1 Inside Ono Sokki Co., Ltd. (72) Inventor Yoshi Ishii 2-4-1 Nishi Shinjuku, Shinjuku-ku, Tokyo Inside Ono Sokki Co., Ltd. (56) References JP-A-4-72542 ( JP, A) JP-A-4-71147 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 1/22

Claims (4)

(57) [Claims] 1. A divided exhaust gas is introduced into a dilution tunnel.
And a number of bypass pipes.
A divider that divides the exhaust gas of the engine
A high-pressure air outlet opening in the vicinity of the introduction pipe outlet in a channel, and a multi-tube type for measuring exhaust gas of an engine that controls air supplied from the high-pressure air outlet to control the pressure of the introduction pipe outlet. In the split-flow dilution tunnel, before the exhaust gas measurement, the optimal differential pressure value between the bypass pipe outlet pressure and the inlet pipe outlet pressure is measured for each operation mode of the engine at the set exhaust gas split ratio, and the exhaust gas measurement is performed. The above-mentioned bypass pipe outlet pressure in each operation mode
Controlling the air supplied from the high-pressure air outlet so that the differential pressure between the pressure and the inlet pipe outlet pressure becomes the optimum differential pressure value in each of the operation modes. 2. The method according to claim 1, wherein an intake air amount and a fuel flow rate of the engine in each operation mode are measured at the time of measuring the optimum differential pressure value, and an operation mode is determined based on the intake air amount and the fuel flow rate at the time of exhaust gas measurement. The method for controlling a multitubular split-flow dilution tunnel according to claim 1. 3. The divided exhaust gas is introduced into a dilution tunnel.
And a number of bypass pipes.
A divider that divides the exhaust gas of the engine
A high-pressure air outlet opening in the vicinity of the introduction pipe outlet in the channel, and a differential pressure value between the exit pressure of the bypass pipe and the introduction pipe exit pressure in each operation mode at the time of exhaust gas measurement is measured in advance. Control means for controlling air supplied from the high-pressure air outlet so that an optimum differential pressure value (a differential pressure value to be a set split ratio) in an operation mode is obtained. Multi-tube split-flow dilution tunnel for measurement. 4. An engine according to claim 1, further comprising an intake air amount detecting means for detecting an intake air amount of said engine, and a fuel flow rate detecting means for detecting a fuel flow rate. The multi-tube split-flow dilution tunnel according to claim 3, wherein the operation mode is determined.