JP2998756B1 - Exhaust gas sampling device - Google Patents

Abstract

To provide an exhaust gas sampling device capable of correctly introducing exhaust gas at the time of starting into an exhaust gas collecting bag. SOLUTION: Before turning on a starter of an engine,
Closing the first outlet (40b) of the flow path switching valve (40),
The second outlet (40c) is opened, and a dummy signal is sent from the control panel (300) to open the variable valve (33) of the mass flow controller (30) so that the exhaust gas flows at a flow rate proportional to the exhaust gas flow rate after starting. Degree. When the starter of the engine is turned on and the output voltage Vf of the exhaust gas flow meter (10) exceeds a predetermined value Va, the flow path switching valve is switched so that the first outlet is opened and the second outlet is closed. The variable valve of the mass flow controller is controlled based on the signal of the exhaust gas flow meter so that the exhaust gas flows at a flow rate proportional to the exhaust gas flow rate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas collecting apparatus for collecting exhaust gas, and more particularly to an exhaust gas collecting apparatus for collecting exhaust gas for analyzing exhaust gas discharged from a vehicle.

[0002]

2. Description of the Related Art An exhaust gas test of a vehicle is performed by operating the vehicle according to a predetermined mode and collecting a part of the exhaust gas discharged from the vehicle at that time by an exhaust gas sampling device. At present, exhaust gas having a flow rate proportional to the amount of exhaust gas exhausted from a vehicle is guided to an exhaust gas collecting bag and collected, and the exhaust gas collected in the exhaust gas collecting bag is analyzed.

[0003] For this purpose, first, an exhaust gas flow rate measuring means for measuring the exhaust gas flow rate from the exhaust pipe and generating a signal corresponding to the exhaust gas flow rate is provided immediately downstream of the exhaust pipe of the vehicle. . The opening degree of the introduction path is controlled to an introduction path downstream of the exhaust gas flow rate detection means and at least part of the exhaust gas whose flow rate is measured by the exhaust gas flow rate measurement means to the exhaust gas collection bag. An introduction path opening control means called a mass flow controller is provided, and the mass flow controller sends the exhaust gas having a flow rate proportional to the exhaust gas flow rate to the exhaust gas collecting bag based on a signal generated by the exhaust gas flow rate measuring means. The opening degree of the introduction path is controlled so as to be introduced (Japanese Patent Laid-Open No. 7-3)
No. 5660).

This mass flow controller has a flow rate sensor and a variable valve, and the flow rate indicated by the flow rate sensor, that is, the flow rate of the exhaust gas introduced into the exhaust gas collecting bag, is measured by the exhaust gas flow rate measuring means. The opening of the variable valve is controlled so as to be a value proportional to the gas flow rate.

[0005]

The analysis of the exhaust gas is performed by sampling the exhaust gas when the vehicle is operated in a predetermined mode. In recent years, however, the influence of the exhaust gas at the time of starting has been increasing. Therefore, it is extremely important to accurately collect the exhaust gas at the time of starting. However, the above-mentioned mass flow controller has poor response in a low flow rate region, and when collecting exhaust gas from the start of the engine, the opening of the variable valve becomes an opening proportional to the amount of exhaust gas. It takes time (for several seconds), and the exhaust gas at the time of starting cannot be correctly guided to the exhaust gas collecting bag. The present invention has been made in view of the above problems, and has as its object to provide an exhaust gas sampling device that can correctly introduce exhaust gas at the time of starting into an exhaust gas collection bag.

[0006]

According to the first aspect of the present invention, a signal is provided downstream of an exhaust pipe of a vehicle, and measures a flow rate of the exhaust gas from the exhaust pipe to correspond to the flow rate of the exhaust gas. Exhaust gas flow rate measuring means for generating the exhaust gas flow rate, and an introduction path for introducing at least a part of the exhaust gas whose flow rate is measured by the exhaust gas flow rate measuring means downstream of the exhaust gas flow rate detecting means to the exhaust gas collecting bag. An introduction path opening degree control means for controlling an opening degree, wherein an exhaust gas having a flow rate proportional to the exhaust gas flow rate is introduced into the exhaust gas collection bag based on a signal generated by the exhaust gas flow rate measurement means. Introduction path opening control means capable of controlling the introduction path opening degree, pseudo signal generation means for sending a pseudo signal for setting the introduction path opening degree to a predetermined opening degree to the introduction path opening degree control means, and introduction path opening degree The communication destination of the introduction path on the downstream side of the control means Flow path switching means capable of instantaneously switching between an exhaust gas collection bag or a discharge pipe to the outside, and a flow path switching means for measuring exhaust gas at the start of the engine from before the start of the engine. The communication destination of the introduction path on the downstream side of the introduction path opening control means is set to the external discharge pipe, and a pseudo signal is sent to the introduction path opening control means by the pseudo signal generation means to completely close the introduction path. When the engine is started and the exhaust gas flow rate measured by the exhaust gas flow rate measuring means exceeds a predetermined value, the introduction path is opened by a signal generated by the pseudo signal generating means. Control is stopped, the opening of the introduction path is switched to control based on the signal generated by the exhaust gas flow rate measuring means, and the flow path switching means is introduced downstream of the introduction path opening control means. Switching the communicating destination exhaust gas collecting bag, an exhaust gas collecting apparatus that is provided.

According to the exhaust gas sampling apparatus configured as described above, when measuring the exhaust gas at the time of starting the engine, the flow path switching means introduces the exhaust gas downstream of the introduction path opening control means from before the start of the engine. The communication destination of the path is set to the external exhaust pipe, and a pseudo signal is sent to the introduction path opening control means by the pseudo signal generation means, the opening of the introduction path is set to a minute opening which is not fully closed, and the engine is started. When the exhaust gas flow rate measured by the exhaust gas flow rate measuring means exceeds a predetermined value, the control of the opening degree of the introduction path by the signal generated by the pseudo signal generating means is stopped, and the opening degree of the introduction path is stopped. To the control based on the signal generated by the exhaust gas flow rate measuring means, and the communication destination of the introduction path downstream of the introduction path opening degree control means can be switched to the exhaust gas collecting bag by the flow path switching means. Since, at the time of starting the engine taken of the exhaust gas is carried out without using a rising portion from responsive poor zero inlet channel opening control means.

According to a second aspect of the present invention, in the first aspect of the present invention, the pseudo signal generated by the pseudo signal generating means to the introduction path opening control means before the start of the engine includes the pseudo signal after the start of the introduction path opening. An exhaust gas sampling device provided with a pseudo signal indicating an opening degree at which exhaust gas flows substantially equal to a flow rate proportional to an exhaust gas flow rate is provided. According to the exhaust gas sampling apparatus configured as described above, the pseudo signal that the pseudo signal generating means sends to the introduction path opening control means from before the start of the engine converts the opening degree of the introduction path to the exhaust gas flow rate after the start. The opening degree at which the exhaust gas flows substantially equal to the proportional flow rate is set, and the difference in the opening degree of the introduction path due to switching from the pseudo signal to the control based on the signal generated by the exhaust gas flow rate measuring means can be almost eliminated.

According to a third aspect of the present invention, in the first aspect of the invention, when measuring the exhaust gas when the engine is stopped, the outlet of the collected exhaust gas flow rate control means is switched by the flow path switching means simultaneously with the stop of the engine. An exhaust gas sampling device is provided that is switched to communicate with an external exhaust pipe. According to the exhaust gas sampling device configured as described above,
At the same time as the engine is stopped, the outlet of the collected exhaust gas flow control means is instantaneously switched by the flow path switching means so as to communicate with the external exhaust pipe, and thereafter, nothing is introduced into the exhaust gas collecting bag. .

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a view showing the overall configuration of an exhaust gas sampling apparatus according to the present invention, and shows a chassis dynamometer 2 disposed inside an exhaust gas measurement chamber 100.
The driving wheel 1a of the vehicle 1 is mounted on the vehicle 00, and the vehicle 1 is driven according to a predetermined mode. An inlet 10a of an exhaust gas flowmeter 10 is connected to an exhaust pipe 1a of the vehicle 1 via a first pipe 11, and the exhaust gas flowmeter 10 is configured to output a flow rate of exhaust gas discharged from the exhaust pipe 1a of the vehicle 1. And a signal corresponding to the flow rate is generated, and the control panel 3
Send to 00.

An outlet 10b of the exhaust gas flowmeter 10 is connected to an inlet 20a of a pump 20 via a second pipe 12, and an outlet 20b of the pump 20 is connected via a third pipe 13 as a collecting gas flow control means. It is connected to the entrance 30a of the mass flow controller 30. In the middle of the second pipe 12, a seventh pipe 17 having an outlet outside the exhaust gas measurement chamber 1 is connected. An eighth pipe 18 is connected in the middle of the third pipe 13, and the eighth pipe 18 is opened to the outside of the exhaust gas measurement chamber 100 via a bypass control valve 60.

The pump 20 rotates at a constant speed during measurement,
A part of the exhaust gas discharged from the exhaust pipe 1a of the vehicle 1 is pumped toward the mass flow controller 30, and the bypass control valve 60 is connected to the outside through the eighth pipe 18 so that the pressure at the inlet 30a of the mass flow controller 30 becomes constant. To control the amount of exhaust gas discharged to the

The mass flow controller 30 has a flow rate sensor 3 for detecting the flow rate of exhaust gas passing through the internal flow path.
1. A variable throttle valve 32 is provided, and an exhaust gas collecting bag 5 is provided.
Exhaust gas flow meter 1
The opening of the variable throttle valve 32 is controlled such that 0 becomes a value proportional to the measured exhaust gas flow rate. This is done so that the flow rate detected by the flow rate sensor 31 becomes a flow rate corresponding to the flow rate of the exhaust gas proportional to the flow rate of the exhaust gas.
The opening degree is controlled by feedback control.

The outlet 30b of the mass flow controller 30
Is the inlet 4 of the flow path switching valve 40 via the fourth pipe 14
0a, the first outlet 40 of the flow path switching valve 40
b is connected to an exhaust gas collecting bag 50 via a fifth pipe 15, and a sixth pipe 16 having an outlet outside the exhaust gas measuring chamber 100 is connected to a second outlet 40 c of the flow path switching valve 40. ing. The flow path switching valve 40 can instantaneously switch the destination of the exhaust gas passing through the mass flow controller 30 to the exhaust gas collecting bag 50 or the outside.

FIG. 2 is a time chart for explaining the sampling of the exhaust gas by the exhaust gas sampling apparatus of the present invention configured as described above. In FIG. 2, (A) shows a signal voltage Vf indicating the exhaust gas flow rate generated by the exhaust gas flow meter 10. Va is a predetermined determination value. (B) shows the flow rate of the exhaust gas to be collected in the exhaust gas collecting bag 50 in proportion to the exhaust gas flow rate shown in (A). In the figure, (A)
The value of (B) with respect to the value of is shown on the order of a quarter, but in practice is much less. (C) shows the variable throttle valve 32 of the mass flow controller 30.
The opening indicated by the dashed line is the opening opened by the pseudo signal before the engine of the vehicle 1 is started.
The opening indicated by the two-dot chain line is proportional to the exhaust gas flow rate based on the signal of the exhaust gas flow meter after the start.
(D) shows the communication destination of the outlet of the flow path switching valve 40. (E) shows the flow rate of the exhaust gas actually flowing to the exhaust gas collecting bag 50 by the combination of (C) and (D).

First, the sampling of the exhaust gas at the time of starting will be described with reference to the left part of the time chart of FIG. 2 shown above. At the time of collecting the exhaust gas at the time of starting, from a predetermined time point t ₀ before a starter (not shown) of the vehicle 1 is turned on, first,
As shown in (D), after opening the second outlet 40c of the flow path switching valve 40 and communicating the downstream side of the mass flow controller 30 to the outside, a pseudo signal is sent from the control panel 300 to the mass flow controller 30, and The opening degree is set to be proportional to the exhaust gas flow rate during idling (dotted line).
Although not shown in FIG. 2, the pump 20 also starts operating at t ₀ . Incidentally, if the t ₀ to pre extent than ON time of the starter is appropriately determined from the experimental results and the like.

Then, when the starter is turned on, FIG.
As shown in (A), the signal generated by the exhaust gas flow meter
The signal voltage Vf immediately rises and a predetermined judgment value Va
Exceeds. Then, as shown in FIG.
T when the Vf of Va exceeds Va ₁And mass flow control
Controller 30 stops controlling the variable throttle valve 32 by the pseudo signal.
And the signal voltage Vf generated by the exhaust gas flowmeter 10 is
Is switched to the control of the variable valve based on the control signal (two-dot chain line). simultaneous
In the meantime, as shown in FIG.
0, the first outlet 40b is opened, and the second outlet 40c is closed.
Through the exhaust gas flow meter 10
Exhaust gas into the exhaust gas collection bag.
You.

As a result, a flow as shown in the left part of FIG. 2E is caused to flow.
(B), the flow rate of the exhaust gas to be introduced into the collection bag shown in the left part of FIG. 4B is proportional to the exhaust gas from the beginning when the starter is turned on and engine cranking is started. Exhaust gas at the flow rate is correctly collected in the exhaust gas collection bag.

Next, the sampling of exhaust gas when the engine is stopped will be described with reference to the right part of the time chart of FIG. Turn off ignition switch of vehicle
Then, when the engine is stopped, the output voltage Vf of the exhaust gas flowmeter immediately drops sharply, and falls below the determination value Va. Therefore, this, at time t ₂ the output voltage Vf of the exhaust the exhaust gas flowmeter 10 is below the determination value Va, as shown in (D) in FIG. 2, the flow path switching valve 40 second outlet 40c Is opened, and the first outlet 40b is switched to be closed so that the exhaust gas that has passed through the exhaust gas flowmeter 10 is discharged to the outside.

Since the flow path switching valve 40 operates instantaneously, extra gas is prevented from being introduced into the exhaust gas collecting bag 50 due to a delay in closing the variable throttle valve 32 of the mass flow controller 30 or a defective seal. You. As a result, when the engine is stopped, a flow rate as shown in the right part of FIG. 2 (E) is caused to flow, which is caused by the trapping shown in the right part of FIG. 2 (B). The flow rate of the exhaust gas to be introduced into the collection bag is made equal to that of the exhaust gas, and the exhaust gas having a flow rate proportional to the exhaust gas at the time of stoppage is correctly collected in the exhaust gas collection bag.

The right part of FIG. 2 shows a case where it takes a long time until the exhaust gas is collected again after the engine is stopped. However, the engine is restarted immediately and the exhaust gas at that time is restarted. when performing the collection of gas, the output voltage Vf of the exhaust the exhaust gas flowmeter 10 at time t ₂ to below the determination value Va, it may be supplied to the pseudo signal.

FIG. 3 is a flowchart of the control of the control panel 300 for executing the above-mentioned sampling. In step 20, an input signal is processed. Step 30 is a step of determining whether or not a flag indicating that the mass flow controller 30 is controlled by a signal proportional to the exhaust gas flow rate is ON.
The process proceeds to 0, and it is determined whether or not the outlet of the flow path switching valve 40 is communicated with the outside (the first outlet 40b is closed and the second outlet 40c is open). If a negative determination is made in step 40, the outlet of the flow path switching valve 40 communicates with the outside in step 50, and if an affirmative determination is made, the process directly proceeds to step 60 where the signal voltage Vf of the exhaust gas flowmeter is set to Va. It is determined whether it is greater than or equal to. Before the engine is started, a negative determination is made in step 60 and the routine proceeds to step 70, in which a pseudo signal is sent to the mass flow controller 30 and step 150 is executed.
Go to and return.

When the engine is started, step 20,
The process proceeds to 30, 40, and 60, and the affirmative determination is made in step 60, and the process proceeds to step 90. In step 90, it is determined whether or not the outlet of the flow path switching valve 40 is communicated with the collection bag 50 (the first outlet 40b is open and the second outlet 40c is closed). Immediately after the start, a negative determination is made and the routine proceeds to step 100, where the outlet of the flow path switching valve 40 is communicated with the collection bag 50, and the routine proceeds to step 110. At step 110, a signal proportional to the exhaust gas flow rate is sent to the mass flow controller 30. At step 120, a flag indicating that the mass flow controller 30 is controlled by the signal proportional to the exhaust gas flow rate is turned on, and the routine proceeds to step 150. To return.

During operation, an affirmative determination is made in step 30 and the routine proceeds to step 80, where a positive determination is made in step 80 and a positive determination is also made in step 90.
0, 80, 90, 110, 120, 150 are repeated.
When the engine is stopped, the signal voltage Vf of the exhaust gas flowmeter becomes smaller than Va, and a negative determination is made in step 80, and the routine proceeds to step 130, where the outlet of the flow path switching valve 40 is communicated to the outside (the first outlet 40b is closed). , The second exit 40c
(Open), the flag XMC is turned off in step 140, and the process ends.

[0025]

According to the invention described in each of the claims, when the engine is started, the introduction path opening control means is set to a small opening degree which is not fully closed. Since the bad area is not used, it is possible to prevent the exhaust gas from being missed at the start of the engine and to obtain the correct exhaust gas. In particular, according to the second aspect, the pseudo signal that the pseudo signal generating means sends to the introduction path opening control means before the start of the engine changes the degree of opening of the introduction path to a flow rate proportional to the exhaust gas flow rate after the start. The opening degree through which the exhaust gas flows are substantially equal, and the difference in the opening degree of the introduction path due to the switching from the pseudo signal to the control based on the signal generated by the exhaust gas flow rate measuring means is almost eliminated, so that the correct exhaust gas can be collected. . According to the third aspect, simultaneously with the stop of the engine, the outlet of the trapped exhaust gas flow control means is instantaneously switched by the flow path switching means so as to communicate with the external exhaust pipe. Since nothing is introduced into the collecting bag, correct exhaust gas can be collected even when the machine is stopped.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a time chart illustrating sampling of exhaust gas according to the embodiment of the present invention.

FIG. 3 is a flowchart of control of exhaust gas sampling.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Exhaust exhaust gas flow meter 20 ... Pump 30 ... Mass flow controller 40 ... Flow path switching valve 50 ... Exhaust gas collection bag 60 ... Bypass control valve 200 ... Chassis dynamometer 300 ... Control panel

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-312695 (JP, A) JP-A-7-35659 (JP, A) JP-A-6-294719 (JP, A) JP-A-10-1998 153534 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 1/22

Claims (3)

(57) [Claims] 1. An exhaust gas flow rate measuring means disposed downstream of an exhaust pipe of a vehicle, for measuring an exhaust gas flow rate from the exhaust pipe, and generating a signal corresponding to the exhaust gas flow rate. An introduction path opening degree control means for controlling an opening degree of an introduction path for introducing at least a part of the exhaust gas whose flow rate is measured by the exhaust gas flow rate measurement means downstream of the gas flow rate detection means into the exhaust gas collection bag. The opening degree of the introduction path can be controlled so that the exhaust gas having a flow rate proportional to the exhaust gas flow rate is introduced into the exhaust gas collecting bag based on the signal generated by the exhaust gas flow rate measuring means. Control means, a pseudo signal generating means for sending a pseudo signal for setting the opening of the introduction path to a predetermined opening degree to the introduction path opening degree control means, a communication destination of the introduction path on the downstream side of the introduction path opening degree control means, Exhaust gas collection bag or exhaust to the outside Flow path switching means capable of instantaneously switching between the pipe and the pipe, and when measuring exhaust gas at the time of starting the engine, the flow path switching means downstream of the introduction path opening control means from before the start of the engine. The communication destination of the introduction path is set to the external discharge pipe, and a pseudo signal is sent to the introduction path opening control means by the pseudo signal generation means to set the opening degree of the introduction path to a minute opening which is not fully closed. When the exhaust gas flow rate measured by the exhaust gas flow rate measuring means exceeds a predetermined value, the control of the opening degree of the introduction path by the signal generated by the pseudo signal generation means is stopped, and The opening is switched to control based on the signal generated by the exhaust gas flow rate measuring means, and the flow path switching means is used to cut the communication destination of the introduction path downstream of the introduction path opening control means to the exhaust gas collection bag. Obtain, exhaust gas collection apparatus characterized by. 2. A pseudo signal which the pseudo signal generating means sends to the introduction path opening control means before the start of the engine is such that the exhaust gas has an opening degree of the introduction path substantially equal to a flow rate proportional to the exhaust gas flow rate after the start. The exhaust gas sampling device according to claim 1, wherein the signal is a pseudo signal indicating a flowing opening degree. 3. The method according to claim 3, wherein at the time of measurement of the exhaust gas when the engine is stopped, the outlet of the collected exhaust gas flow control means is switched by the flow path switching means so as to communicate with the external exhaust pipe simultaneously with the stop of the engine. The exhaust gas sampling device according to claim 1.