JP2000088719A - Division ratio-controlling method in flow diverging diluting tunnel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a division ratio controlling method which can be adapted to transient operational mode. SOLUTION: Exhaust gases from an engine are introduced to an exhaust pipe 3, and part of them is diverged to a diluting tunnel 1 by an exhaust gas introducing pipe 5 to control the division ratio of the exhaust gases by the quantity of flow of high-pressure air injection nozzles 6 and 6. A central arithmetic processing unit 14 stores (learns) the discharge amount of the exhaust gases every elapsed time from the start of operational mode to its completion, next, stores (learns) the amount of operation at the time of controlling the quantity of flow injection of high-pressure air so that a division ratio may become a predetermined value at predetermined points where the above-mentioned amount of discharge is different, and creates a table of the amount of control over the amount of operation which can be controlled at a desired resolution from the stored amount of discharge and amount of operation. The above-mentioned high-pressure air is controlled to control the division ratio of exhaust gases according to the table of the amount of control. As the table of the amount of control is corrected by repeated learning, it becomes possible to perform accurate control and to perform the real-time display of a division ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a split ratio control method in a split-flow dilution tunnel, and more particularly, to a split ratio control method in a split-flow dilution tunnel capable of coping with a transient operation mode.

[0002]

2. Description of the Related Art In order to conduct research for reducing particulate matter emitted by a diesel engine, a method for accurately and easily measuring the amount of exhaust is indispensable. Since the tunnel is a large facility and requires a lot of expense, it divides the exhaust gas,
Divergent dilution tunnels have been developed that guide only a portion to a small dilution tunnel. For example, there is a so-called multitubular split-flow type dilution tunnel. In this dilution tunnel, the flow is divided by a number of small tubes having the same size and shape. One of them is configured to guide the exhaust gas to the dilution tunnel, and the other narrow tube is guided to the exhaust flue via the surge tank. The diverted exhaust gas is mixed with clean air in the tunnel to become diluted exhaust gas. A part of the diluted exhaust gas is sampled, the particulate matter is collected by a filter, and the emission amount is measured.

[0003] In order to measure particulate matter in a split-flow dilution tunnel, the ratio of the total flow rate of the exhaust gas of the engine to the flow rate of the split flow into the dilution tunnel with respect to changes in the operating conditions of the engine, that is, the division of the exhaust gas, It must be controlled to keep the ratio constant. Conventionally, feedback control has been performed for such control.

[0004]

In recent years, as the performance of diesel engines has been improved, it has been required to measure not only the exhaust gas concentration in the conventional steady operation mode but also the exhaust gas concentration and the particulate matter in the transient operation mode. Have been. The operation mode (rotation speed and load factor) of the engine is determined every time. Recently, the development of an engine in an operation mode requiring an extremely steep transient response of 0.1 seconds or less has been promoted. In such an operation mode, the conventional control method has a problem that the response is slow, so that the exhaust gas concentration cannot be accurately measured.

The present invention has been made in view of the above circumstances, and the present invention provides a method of controlling a split ratio in a split-flow dilution tunnel that enables control of an exhaust gas split ratio in a steep transient operation mode. Is what you do.

[0006]

According to a first aspect of the present invention, a part of exhaust gas discharged from an engine is divided into a dilution tunnel, and a flow rate of the divided exhaust gas is controlled by an injection flow rate of high-pressure air. In the method of controlling the division ratio in the dilution tunnel, the flow rate of the exhaust gas after a part of the exhaust gas is divided is Qex ′, the flow rate Qin of the air introduced into the dilution tunnel, the injection flow rate of the high-pressure air is Qc, and the dilution flow rate is Qc. Assuming that the total flow rate at the tunnel exit is Qcon, the exhaust gas split ratio SR is measured as SR = [Qex '{Qcon- (Qin + Qc)}] + 1. The discharge flow rate of the exhaust gas is stored for each elapsed time from the start to the end of the operation mode, and the discharge flow rate from the start to the end of the operation mode is different in a state where the exhaust gas is divided. A manipulated variable when controlling the injection flow rate of the high-pressure air so that the exhaust gas division ratio SR at a point becomes a predetermined value is stored, and a desired exhaust gas flow rate within the flow rate range of the exhaust gas flow rate is stored based on the stored discharge flow rate and manipulated variable. A control amount table of an operation amount capable of controlling the split ratio SR at a resolution of is created and stored, and when the engine is operated in the operation mode, the flow rate of the split ratio according to the control amount table for each elapsed time. , So that the division ratio can be controlled corresponding to the operation mode having a steep transient characteristic.

According to a second aspect of the present invention, in the first aspect of the present invention, the division ratio SR from the start to the end of the operation mode is displayed in real time, and the control result of the division ratio is verified. At the same time, it is possible to easily determine whether the control program needs to be improved.

According to a third aspect of the present invention, in the first aspect of the invention, the operation of creating the control amount table is repeated by verifying the control result of the division ratio, thereby improving the accuracy of the prediction control. This enables accurate division ratio control to be performed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing the overall construction of a diversion tunnel for explaining an embodiment of the present invention. In the drawing, reference numeral 1 denotes a dilution tunnel into which dilution air is introduced, and 2 denotes a dilution tunnel. The mixing orifice 3 is provided with an exhaust pipe through which exhaust gas is introduced, 4 is a venturi pipe provided in the exhaust pipe 3, 5 is an exhaust gas introducing pipe which divides exhaust gas from the exhaust pipe 3 to the dilution tunnel 1, 'Is an on-off valve installed in the exhaust gas introduction pipe 5, 6 is a high-pressure air injection nozzle provided in the dilution tunnel 1 near the outlet of the exhaust gas introduction pipe 5, 7
Is a high pressure air flow meter, 8 is a high pressure air control valve, 9
Is a valve control device for controlling the control valve 8.
The control valve 8 is a high-speed response type and uses a digital control valve for switching and controlling a plurality of ports.

Reference numeral 10 is a dilution air flow meter, 11 is a heat exchanger, 12 is a sonic nozzle, 13 is an exhaust gas flow meter, 14
Is a central processing unit. The central processing unit 14
High pressure air flow meter 7, Dilution air flow meter 10, Sonic nozzle 1
2. The valve control device 9 is controlled in accordance with the flow rate information from the exhaust gas flow meter 13 to keep the flow rate ratio of the exhaust gas constant. Reference numeral 15 denotes a display device, and reference numeral 16 denotes an exhaust gas analyzer arranged in the dilution tunnel 1.

The manner in which the exhaust gas split ratio is kept constant will be described. The split ratio SR is given by: SR = Qex ÷ Qind = (Qex ′ + Qind) ÷ Qind = (Qex ′ ÷ Qind) +1 (1) , Qex is the total amount of exhaust gas from the engine, Qind
Is the exhaust gas partial flow rate, and Qex 'is the exhaust gas flow rate measured by the exhaust gas flow meter 13. Further, Qc is the injection amount of the high pressure air at the injection nozzles 6 and 6, Qcon is the flow rate at the sonic nozzle 12, and the mass flow rate is a constant value. Therefore, Qcon = Qin + Qind + Qc, that is, Qind = Qcon- (Qin + Qc) (2) Equation (2) is substituted into Equation (1), and SR = [Qex '{Qcon- (Qin + Qc)}] + 1 Equation (3) That is, Qin = Qcon- {Qex'} (SR-1) ｝ −Qc (4) It is assumed that all the flow values are converted into mass flow rates.

As described above, the division ratio is obtained from the above equation (3). That is, it is obtained by measuring each flow rate in the exhaust gas flow meter 13, the sonic nozzle 12, the dilution air flow meter 10, and the high pressure air flow meter 7. Therefore, when the exhaust gas flow rate Qex 'is changed, the flow rate value in each of the flow meters is changed by the central processing unit 1 in order to keep the division ratio constant.
4, the control valve 8 is controlled by the valve controller 9 to change the flow velocity of the injection nozzles 6, 6 to control the exhaust gas partial flow rate Qind. The reason why the partial flow rate Qind is not directly measured here is that if a flowmeter is installed in the exhaust gas introduction pipe 5, floating particles discharged from the engine adhere to the flowmeter. Direct flow measurement is not possible. Similarly, it is the same reason that the total amount Qex of the exhaust gas is not measured directly but is measured downstream of the exhaust gas introduction pipe 5.

Although this can be performed in the steady operation mode, in an operation mode in which a steep transient response is required, various devices cannot follow the mode change and control is difficult.
In view of this, the inventors have focused on the fact that the operation mode is programmed with the engine speed and the load according to the elapsed time, and learned the control program by learning in advance so that it can cope with the steep change mode. .

The procedure for learning the control program will be described below. (Learning of Exhaust Gas Flow Rate) The on-off valve 5 'of the exhaust gas introduction pipe 5 is closed, the operation is performed once in the operation mode to be tested, and the exhaust gas flow rate is measured by the exhaust gas flow meter 13 every time from the start. It is stored (learned) in the central processing unit 14. (Learning the relationship between the exhaust gas flow rate and the valve control amount) Opening the on-off valve 5 'of the exhaust gas introduction pipe 5, operating the engine and changing the exhaust gas flow rate in accordance with the operation mode (usually 4 to 5 points) The operation amount of the valve control device 9 is stored (learned) in the memory of the central processing unit 14 so that the division ratio at the time of the change becomes a predetermined value. (Tabulation of valve operation amount) Based on the learning result described above, the operation amount of the valve control device 9 capable of controlling the flow rate with the required resolution (0.2 to 0.4%) within the flow rate range of the exhaust gas flow rate is shown. It is automatically created by the central processing unit 14 by interpolation and stored as a control amount table. (Learning control) The engine is operated in the learned operation mode, the operation amount of the valve control device 9 corresponding to the learned exhaust gas flow rate is output from the control amount table of the central processing unit 14, and the division ratio SR is kept constant. Is controlled to control the flow rate. (Verification of control result) The division ratio SR is obtained from the above equation (3), and the division ratio SR from the start of operation to the end of operation is displayed on the display device 15 in real time from the central processing unit 14 by graphic or the like, and the control result is verified. I do. (Re-implementation of learning work) When the verification result does not fall within the range of the predetermined division ratio,
If the operating conditions, piping conditions, etc. have changed, the above learning operations (1) to (4) are repeated.

When the engine is operated in the operation mode, the split ratio of the exhaust gas is controlled according to the control amount table thus obtained. Exhaust gas analysis is performed by the exhaust gas analyzer 16 under the controlled split ratio.

[0016]

According to the first aspect of the invention, a part of the exhaust gas discharged from the engine is diverted to the dilution tunnel, and the flow rate of the diverted exhaust gas is controlled by the injection flow rate of the high-pressure air. In the division ratio control method described in the above, the exhaust gas flow rate after a part of the exhaust gas is diverted is changed to Qex 'the flow rate Q of the air introduced into the dilution tunnel.
in, the injection flow rate of the high-pressure air is Qc, and the total flow rate at the exit of the dilution tunnel is Qcon.
Is measured as SR = [Qex '{Qcon- (Qin + Qc)}] + 1. With the exhaust gas diverting stopped, the exhaust gas discharge flow rate is calculated every time elapsed from the start to the end of the operation mode. Then, in a state where the exhaust gas is divided, the discharge flow rate from the start to the end of the operation mode is different from that of the high-pressure air so that the exhaust gas division ratio SR at a different predetermined point becomes a predetermined value. An operation amount when the injection flow rate is controlled is stored, and a control amount table of the operation amount capable of controlling the division ratio SR at a desired resolution within a flow rate range of the exhaust gas flow rate from the stored discharge flow rate and the operation amount. When the engine is operated in the operation mode, the flow rate of the division ratio is controlled in accordance with the control amount table for each elapsed time. It is possible to control the division ratio corresponding to the operation mode with the transient characteristics.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, the division ratio SR from the start to the end of the operation mode is displayed in real time, and the verification of the control result of the division ratio is verified. Therefore, it is possible to easily determine whether the control program needs to be improved.

According to the invention of claim 3, in addition to the effect of the invention of claim 1, the operation of creating the control amount table is repeated by verifying the control result of the division ratio, so that the accuracy of the prediction control is improved. And more accurate division ratio control can be performed.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a diversion dilution tunnel for explaining an embodiment of the present invention.

[Explanation of symbols]

1: dilution tunnel, 2: mixing orifice, 3: exhaust pipe,
4 ... Venturi pipe, 5 ... Exhaust gas introduction pipe, 5 '... On-off valve, 6 ... High pressure air injection nozzle, 7 ... High pressure air flow meter,
8 ... high pressure air control valve, 9 ... valve control device,
10: dilution air flow meter, 11: heat exchanger, 12: sonic nozzle, 13: exhaust gas flow meter, 14: central processing unit, 15: display device, 16: exhaust gas analyzer.

 ──────────────────────────────────────────────────続 き Continuing from the front page (71) Applicant 598157812 Masaki Takamoto 1-1-4 Umezono, Tsukuba City, Ibaraki Pref. Inside the Institute of Metrology, Industrial Technology Institute (71) Applicant 598172181 Satoshi Yamazaki 1-1-1 Umezono Umezono, Tsukuba City, Ibaraki Prefecture 4 Within the Institute of Metrology, Japan Institute of Industrial Technology (74) The above two agents 100079843 Attorney, Akachika Takano (72) The inventor Masaki Takamoto, 1-4-1 Umezono, Tsukuba, Ibaraki Pref. ) Inventor Tetsu Yamazaki 1-4-1 Umezono, Tsukuba, Ibaraki Pref.Institute of Metrology, Institute of Industrial Technology (72) Inventor Katsuo Triangle 3-10-8 Kamiochiai, Shinjuku-ku, Tokyo Oval Co., Ltd. (72) Inventor Tanimoto Jun 3-10-8 Kamiochiai, Shinjuku-ku, Tokyo Inside the oval company (72) Inventor Naoki Matsubara 3-10-8, Kamiochiai, Shinjuku-ku, Tokyo Stock Association F term in the company oval (reference) 2G087 AA15 BB28 CC27 CC29 DD20

Claims (3)

[Claims] 1. A split ratio control method in a split dilution tunnel, wherein a part of exhaust gas discharged from an engine is split into a dilution tunnel, and a flow rate of the split exhaust gas is controlled by an injection flow rate of high-pressure air. When the exhaust gas flow rate after a part of the gas is divided is Qex ′, the flow rate Qin of the air introduced into the dilution tunnel, the injection flow rate of the high-pressure air is Qc, and the total flow rate at the exit of the dilution tunnel is Qcon, The exhaust gas split ratio SR is measured as SR = [Qex '{Qcon- (Qin + Qc)}] + 1. With the exhaust gas diverting stopped, the exhaust gas split ratio SR is calculated for each elapsed time from the start to the end of the operation mode. In a state where the exhaust gas discharge flow rate is stored and then the exhaust gas is divided, the exhaust gas flow rate from the start to the end of the operation mode is different from the exhaust gas split ratio SR at a predetermined point. An operation amount when controlling the injection flow rate of the high-pressure air to be a predetermined value is stored, and the control of the split ratio SR at a desired resolution within a flow rate range of the exhaust gas flow rate is performed based on the stored discharge flow rate and operation amount. Generating and storing a control amount table of an operation amount capable of performing the operation, and when the engine is operated in the operation mode, controlling the flow rate of the division ratio in accordance with the control amount table for each elapsed time. Split ratio control method in dilution tunnel. 2. The split ratio in the split-flow dilution tunnel according to claim 1, wherein the split ratio SR from the start to the end of the operation mode is displayed in real time, and the control result of the split ratio is verified. Control method. 3. The division ratio control method according to claim 1, wherein the operation of creating the control amount table is repeated by verifying the control result of the division ratio.