JP6302593B1 - Exhaust gas analyzer - Google Patents

Abstract

An exhaust gas analyzer capable of accurately measuring the exhaust gas component concentration even immediately after an engine is restarted from a temporarily stopped state during operation of a vehicle. SOLUTION: An exhaust pipe 2, a sampling pipe 4 connecting the exhaust pipe and the concentration detector 3, a pump 5 provided in the sampling pipe and supplying gas to the concentration detector at all times, and an alternative connected to the sampling pipe A gas introduction pipe 6, an alternative gas container 7 connected to the alternative gas introduction pipe and filled with a known alternative gas, a flow path switching valve 8 disposed at a branching portion 4a of the sampling pipe and the alternative gas introduction pipe, A flow path switching control unit 9 that controls the flow path switching means according to the presence or absence of the operation of the engine 1 is provided. When the engine is operating, the upstream side of the branching part in the sampling pipe is connected to the downstream side of the branching part, and the concentration detection part is connected to the exhaust pipe. The concentration detection unit is connected to the alternative gas introduction pipe by being connected to the downstream side of the branching unit. [Selection] Figure 1

Description

  The present invention relates to an exhaust gas analyzer that measures the component concentration of exhaust gas discharged from an engine.

  In recent years, vehicles in which an engine is temporarily stopped during operation of a hybrid vehicle (HEV), an idling stop vehicle, and the like have become widespread, and an exhaust gas analyzer corresponding to measurement of exhaust gas component concentration during operation of such a vehicle has been developed. ing.

  For example, an exhaust gas analyzer described in Patent Document 1 includes an exhaust gas passage through which exhaust gas from an engine flows, an exhaust gas introduction pipe that is branched and connected to the exhaust gas passage, an analysis instrument that is connected to the exhaust gas introduction pipe, An atmosphere introduction pipe branched and connected to the exhaust gas introduction pipe and a flow path switching mechanism provided at a branch portion of the atmosphere introduction pipe in the exhaust gas introduction pipe are provided.

  The analytical instrument operates during the operation of the engine and constantly sucks the gas, and when the engine is in an operating state by the flow path switching mechanism, the upstream side portion of the branch portion in the exhaust gas introduction pipe and the downstream side of the branch portion On the other hand, when the engine is in a temporarily stopped state, the downstream portion of the branch portion in the atmospheric introduction pipe and the exhaust gas introduction pipe is connected.

  According to this configuration, even when the pump of the analytical instrument is operated while the engine is temporarily stopped, the unexpected gas flow from the engine or the atmosphere side to the exhaust gas flow path, the temperature change of the catalyst, the pressure drop of the exhaust port Etc. can be avoided.

  However, since the measurement target components of the analyzer (including exhaust emission control substances) are contained in the atmosphere, in the exhaust gas analysis apparatus described above, the engine is restarted from a temporarily stopped state, and the sampling line of the analytical instrument Immediately after switching from the atmosphere introduction pipe side to the exhaust gas introduction pipe side, there was a drawback that the component concentration of the exhaust gas could not be measured accurately.

Japanese Patent Laying-Open No. 2015-79006

  Accordingly, an object of the present invention is to provide an exhaust gas analyzer that can accurately measure the exhaust gas component concentration even immediately after the engine is restarted from a temporarily stopped state during operation of the vehicle.

In order to solve the above problems, according to the present invention, an exhaust pipe through which exhaust gas of an engine flows, a concentration detection unit for detecting a component concentration of exhaust gas, and a branch connection to the exhaust pipe, the exhaust pipe is connected to the concentration A sampling pipe connected to the detection unit, a pump provided in the exhaust system of the sampling pipe or the concentration detection unit, which supplies gas to the concentration detection unit at all times, and a branch connection upstream of the pump in the sampling pipe An alternative gas introduction pipe, an alternative gas container connected to the alternative gas introduction pipe and filled with zero gas as a known alternative gas , a branch of the alternative gas introduction pipe in the sampling pipe, or in the sampling pipe Monitoring the presence or absence of operation of the engine, the flow path switching means provided on the upstream side of the branching section and the alternative gas introduction pipe, A flow path switching control unit for controlling the flow path switching means according to the presence or absence of the operation, a pressure controller provided in the alternative gas container or the alternative gas introduction pipe, and the pressure control in the alternative gas introduction pipe An overflow pipe branch connected to the downstream side of the vessel, and when the engine is operating, the upstream side of the branch part and the downstream side of the branch part in the sampling pipe are connected simultaneously with the replacement When the gas introduction pipe is closed, the concentration detection unit is connected to the exhaust pipe, and when the engine is temporarily stopped, the alternative gas introduction pipe is connected to the downstream side of the branch part in the sampling pipe. at the same time is, by the upstream side of the branch portion of the sampling tube is closed, so the density detecting unit is connected to the alternate gas inlet tube And a calibration unit that performs zero point correction of the concentration detection unit using data detected by the concentration detection unit when the engine is temporarily stopped, and the calibration unit includes a moving average acquisition time, a correction start time, and A parameter value storage unit in which a concentration threshold value is stored in advance, a time measurement unit that measures an elapsed time after switching the connection of the concentration detection unit from the exhaust pipe to the alternative gas introduction pipe, and the concentration detection unit After switching the connection from the exhaust pipe to the alternative gas introduction pipe, the detection data storage section that sequentially stores the instantaneous concentration value detected by the concentration detection section, and the detection data storage section based on the moving average acquisition time A moving average value calculation unit that sequentially calculates a concentration moving average value using the stored instantaneous concentration value, and each time the concentration moving average value is calculated by the moving average value calculation unit A correction timing for comparing a value obtained by subtracting the moving average acquisition time from a measurement value obtained by the time measurement unit with the correction start time, and outputting a correction start signal when the subtracted value exceeds the correction start time. When the correction start signal is output from the detection unit and the correction timing detection unit, the concentration moving average value calculated by the moving average value calculation unit is compared with the concentration threshold value, and the concentration moving average value is There is provided an exhaust gas analyzer characterized by having a zero point correction unit that performs zero point correction of the concentration detection unit when the concentration threshold is exceeded .

According to the present invention, the connection of the concentration detection unit is switched between the exhaust pipe side and the alternative gas introduction pipe side according to the presence or absence of the operation of the engine, and when the engine is operated, exhaust gas from the engine is supplied to the concentration detection unit, Zero gas as a known alternative gas is supplied to the concentration detection unit when the engine is temporarily stopped.

For this reason, when the engine is temporarily stopped , zero gas as a known alternative gas is supplied to the concentration detection unit, and the concentration detection unit detects the component concentration of the zero gas , while exhaust gas immediately after the engine stops stays in the exhaust pipe. The air is not sucked into the exhaust pipe and does not affect the composition and temperature of the exhaust gas. In addition, since zero gas does not contain the component gas to be detected by the concentration detection unit, it is known in advance that the concentration detection value obtained by the concentration detection unit for zero gas is zero, thereby detecting the concentration when the engine is temporarily stopped. Can be corrected.

When the engine is restarted from the paused state, the concentration detection unit is switched from the alternative gas introduction pipe side to the exhaust pipe side, and exhaust gas is supplied to the concentration detection unit, and detection of the exhaust gas component concentration by the concentration detection unit starts. However, at this time, the detection data of the exhaust gas by the concentration detector can be clearly distinguished from the detection data of zero gas .
As a result, the exhaust gas component concentration can be measured accurately even immediately after the engine is restarted from the paused state.

1 is a block diagram showing a schematic configuration of an exhaust gas analyzer according to one embodiment of the present invention. (A) is a block diagram which shows schematic structure of the exhaust gas analyzer by another Example of this invention, (B) is a block diagram which shows the structure of the calibration part of (A). It is a graph which shows an example of the time change of the concentration instantaneous value obtained in a concentration detection part after switching from the exhaust pipe side of the connection of a concentration detection part to the alternative gas introduction pipe side.

Hereinafter, the configuration of the present invention will be described based on preferred embodiments with reference to the accompanying drawings.
FIG. 1 is a block diagram showing a schematic configuration of an exhaust gas analyzer according to one embodiment of the present invention.
Referring to FIG. 1, 1 is an engine, 2 is an exhaust pipe through which exhaust gas from the engine 1 flows, and 3 is a concentration detection unit that detects a component concentration of exhaust gas.

  A sampling pipe 4 is branched and connected to the exhaust pipe 2, and the sampling pipe 4 connects the exhaust pipe 2 to the concentration detector 3. The sampling tube 4 is provided with a pump 5 that supplies gas to the concentration detector 3 at all times.

  An alternative gas introduction pipe 6 is branched and connected to the upstream side of the pump 5 in the sampling pipe 4, and an alternative gas container 7 is connected to the alternative gas introduction pipe 6. In this embodiment, the alternative gas container 7 and the alternative gas introduction pipe 6 are connected by attaching the pressure controller 10 to the outlet of the alternative gas container 7 and connecting the alternative gas introduction pipe 6 to the pressure controller 10. Has been made.

The alternative gas container 7 is filled with a known alternative gas.
As a known alternative gas, a gas consisting only of a component gas (concentration known) that is a detection target of the concentration detection unit 3, or at least one type and concentration of a component gas (concentration known) that is a detection target of the concentration detection unit 3 Examples thereof include a gas in which at least one kind of component gas that is not a detection target of the detection unit 3 (which may have an indefinite concentration) is mixed, or a gas that includes only a component gas that is not a detection target of the concentration detection unit (which may have an indefinite concentration).

  Further, a flow path switching valve 8 is provided at the branching portion 4 a of the alternative gas introduction pipe 6 in the sampling pipe 4. In this embodiment, the flow path switching valve 8 is a three-way electromagnetic valve.

Furthermore, a flow path switching control unit 9 that monitors the presence or absence of the operation of the engine 1 and controls the flow path switching valve 8 according to the presence or absence of the operation of the engine 1 is provided.
The monitoring of the presence or absence of the operation of the engine 1 by the flow path switching control unit 9 is, for example, monitoring an ignition signal of the engine 1, monitoring an output signal from a sensor that detects the rotation speed of the engine 1, The output signal from the sensor that detects the exhaust gas flow rate flowing through the pipe 2 is monitored, the output signal from the sensor that detects the intake flow rate of the engine 1 is monitored, and the engine stop signal and the fuel supply stop signal are monitored. It is made by things.

  An overflow pipe 11 is branched and connected to the alternative gas introduction pipe 6 on the downstream side of the pressure controller 10.

  When the flow path switching control unit 9 determines that the engine 1 is in an operating state, the flow path switching control unit 9 connects the upstream side of the branching portion 4a and the downstream side of the branching portion 4a in the sampling pipe 4 and at the same time, the alternative gas introduction pipe 6 When the engine 1 is determined to be in a temporarily stopped state, the alternative gas introduction pipe 6 and the downstream side of the branch part 4a in the sampling pipe 4 are connected. At the same time, the concentration detection unit 3 is connected to the alternative gas introduction pipe 6 by closing the upstream side of the branch part 4 a in the sampling pipe 4.

  In this way, according to the exhaust gas analyzer of the present invention, the connection of the concentration detector 3 is switched between the exhaust pipe 2 side and the alternative gas introduction pipe 6 side according to whether the engine 1 is operating or not. While the exhaust gas from the engine 1 is supplied to the unit 3, a known alternative gas is supplied to the concentration detection unit 3 when the engine 1 is temporarily stopped.

  Therefore, when the engine 1 is temporarily stopped, the alternative gas is supplied to the concentration detection unit 3 and the concentration detection unit 3 detects the component concentration of the alternative gas, while the exhaust pipe 2 has exhaust gas immediately after the engine 1 is stopped. Will remain, and the atmosphere will not be sucked into the exhaust pipe 2 to affect the composition and temperature of the exhaust gas.

  Further, since the component gas to be detected by the concentration detector 3 contained in the known gas has a known concentration, the detection data obtained by the concentration detector 3 for the component gas is known in advance and is included in the known gas. The component gas that is not detected by the concentration detector 3 is not detected by the concentration detector 3.

When the engine 1 is restarted from the temporarily stopped state, the gas supply path of the concentration detection unit 3 is switched from the alternative gas introduction pipe 6 to the exhaust pipe 2 side, and exhaust gas is supplied to the concentration detection unit 3. In this case, the exhaust gas detection data by the concentration detector 3 can be clearly distinguished from the alternative gas detection data.
As a result, the exhaust gas component concentration can be accurately measured even immediately after the engine 1 is restarted from the temporarily stopped state.

FIG. 2 shows the configuration of another embodiment of the present invention.
This embodiment is different from the embodiment of FIG. 1 only in that a calibration unit for correcting the zero point of the density detection unit 3 is provided. Therefore, in FIG. 2, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted below.

  Referring to FIG. 2A, in this embodiment, the known alternative gas is made of zero gas, and the exhaust gas analyzer further uses the detection data from the concentration detector 3 while the engine 1 is temporarily stopped. A calibration unit 12 that performs zero point correction of the detection unit 3 is provided.

As shown in FIG. 2B, the calibration unit 12 has a parameter value storage unit 13 in which a moving average acquisition time, a correction start time, and a density threshold value are stored in advance.
Here, the moving average acquisition time, the correction start time, and the density threshold are each defined as follows.
Moving average acquisition time: A time interval for taking a moving average of instantaneous concentration values obtained by the concentration detector 3 after switching the connection from the exhaust pipe 2 to the alternative gas introduction pipe 6 of the concentration detector 3. For example, 5 to 10 seconds is set as the average time.
Correction start time: Time until the zero point correction is started after switching the connection from the exhaust pipe 2 to the alternative gas introduction pipe 6 of the concentration detector 3 (until sufficient gas replacement is performed after switching the pipe line) Time is considered). For example, 1 to 2 minutes is set.
Density threshold: a reference concentration value for determining whether calibration is necessary. Two values, plus and minus, are set across the zero density point.

  The calibration unit 12 also includes a time measurement unit 14 that measures an elapsed time after switching the connection from the exhaust pipe 2 to the alternative gas introduction pipe 6 of the concentration detection unit 3, and an alternative gas from the exhaust pipe 2 of the concentration detection unit 3. After switching the connection to the introduction pipe 6, the detection data storage unit 15 that sequentially stores the instantaneous concentration values detected by the concentration detection unit 3, and the instantaneous concentration stored in the detection data storage unit 15 based on the moving average acquisition time A moving average value calculation unit 16 that sequentially calculates density moving average values using the values is provided.

The calibration unit 12 further compares the value obtained by subtracting the moving average acquisition time from the measurement value obtained by the time measurement unit 14 with the correction start time each time the concentration moving average value is calculated by the moving average value calculation unit 16. when the subtracted value exceeds the correction start time, the correction timing detection unit 17 for outputting a correction start signal, when the correction start signal from the correction timing detection unit 17 is outputted, calculated by the moving average calculation section 16 The density moving average value is compared with the density threshold value, and when the density moving average value exceeds the density threshold value, the zero point correcting unit 18 that performs the zero point correction of the density detecting unit 3 is provided.

Next, the operation of the calibration unit 12 will be specifically described.
FIGS. 3A to 3C are examples of temporal changes in the concentration instantaneous value obtained by the concentration detection unit 3 after switching from the exhaust pipe 2 side of the connection of the concentration detection unit 3 to the alternative gas introduction pipe 6 side. It is a graph to show. In the graphs of FIGS. 3A to 3C, the vertical axis represents the instantaneous concentration value (% FS), and the horizontal axis represents the elapsed time (seconds).

Referring to FIG. 3A, when the concentration detection unit 3 is switched from the exhaust pipe 2 to the alternative gas introduction pipe 6 (point P ₁ ), zero gas from the alternative gas introduction pipe 6 to the concentration detection unit 3 is changed. Supply is started, and gas replacement (exhaust gas → zero gas) in the concentration detection unit 3 proceeds, whereby the instantaneous concentration value obtained by the concentration detection unit 3 rapidly decreases.

In addition, after the concentration detection unit 3 is switched from the exhaust pipe 2 to the alternative gas introduction pipe 6, the detection data moving average is calculated based on the concentration instantaneous value stored in the detection data storage unit 15 for each moving average acquisition time. A density moving average value is calculated by the value calculation unit 16.
Each time the concentration moving average value is calculated, the correction timing detection unit 17 compares the value obtained by subtracting the moving average acquisition time from the measurement value obtained by the time measurement unit 14 with the correction start time.

Then, as shown in FIG. 3B, when the subtracted value exceeds the correction start time (point P ₂ ), a correction start signal is output from the correction timing detection unit 17.
When the correction start signal is output, the zero point correction unit 18 compares the density moving average value calculated by the moving average value calculation unit 16 at that time with the density threshold (± δ), and the density moving average value is calculated. If it is determined that the density threshold (± δ) is exceeded, the zero point correction unit 18 performs zero point correction of the density detection unit 3 (point P _{3 in} FIG. 3C).

  According to this embodiment, in addition to the effect obtained in the embodiment of FIG. 1, the effect that the zero point correction of the concentration detector 3 can be automatically performed while the engine 1 is temporarily stopped is obtained.

  The preferred embodiments of the present invention have been described above. However, the configuration of the present invention is not limited to the above-described embodiments, and those skilled in the art will recognize various modifications within the scope of the configurations described in the claims of the present application. You can devise.

  For example, in the embodiment described above, the flow path switching valve is arranged at the branch portion of the alternative gas introduction pipe in the sampling pipe as the flow path switching means, but instead of this configuration, the branch in the sampling pipe is used as the flow path switching means. The first and second flow path switching valves are arranged on the upstream side of the unit and the alternative gas introduction pipe, respectively, and when the engine is in operation, the first flow path switching valve is opened and the second flow path switching is performed at the same time. When the valve is closed and the engine is in a temporarily stopped state, the second flow path switching valve may be opened at the same time as the first flow path switching valve is closed.

  Further, for example, in the above embodiment, the pressure controller is provided in the alternative gas container, but the pressure controller may be provided in the alternative gas introduction pipe. In the above embodiment, the pump for supplying gas to the concentration detection unit is provided on the sampling pipe (upstream side of the concentration detection unit), but the pump is provided on the exhaust system of the concentration detection unit (downstream side of the concentration detection unit). You can also.

DESCRIPTION OF SYMBOLS 1 Engine 2 Exhaust pipe 3 Concentration detection part 4 Sampling pipe 4a Branch part 5 Pump 6 Alternative gas introduction pipe 7 Alternative gas container 8 Flow path switching valve 9 Flow path switching control part 10 Pressure controller 11 Overflow pipe 12 Calibration part 13 Parameter value Storage unit 14 Time measurement unit 15 Detection data storage unit 16 Moving average value calculation unit 17 Correction timing detection unit 18 Zero point correction unit

Claims (1)

An exhaust pipe through which the exhaust gas of the engine flows,
A concentration detector for detecting the concentration of exhaust gas components;
A sampling pipe that is branched and connected to the exhaust pipe, and connects the exhaust pipe to the concentration detection unit;
A pump that is provided in an exhaust system of the sampling pipe or the concentration detector , and constantly supplies gas to the concentration detector;
An alternative gas introduction pipe branched and connected to the upstream side of the pump in the sampling pipe;
An alternative gas container connected to the alternative gas introduction pipe and filled with zero gas as a known alternative gas;
A branch section of the alternative gas introduction pipe in the sampling pipe, or a flow path switching means provided on the upstream side of the branch section and the alternative gas introduction pipe in the sampling pipe;
A flow path switching control unit that monitors the presence or absence of the operation of the engine and controls the flow path switching means according to the presence or absence of the operation;
A pressure controller provided in the alternative gas container or the alternative gas introduction pipe;
An overflow pipe branched and connected to the downstream side of the pressure controller in the alternative gas introduction pipe,
When the engine is in operation, the upstream side of the branching portion and the downstream side of the branching portion in the sampling pipe are connected, and at the same time, the alternative gas introduction pipe is closed, so that the concentration detection section is While the engine is temporarily stopped, the alternative gas introduction pipe is connected to the downstream side of the branch part of the sampling pipe, and at the same time, the upstream side of the branch part of the sampling pipe is closed. The concentration detector is connected to the alternative gas introduction pipe, and
A calibration unit that performs zero point correction of the concentration detection unit using data detected by the concentration detection unit when the engine is temporarily stopped,
The calibration unit is
A parameter value storage unit in which the moving average acquisition time, the correction start time, and the concentration threshold value are stored in advance;
A time measuring unit for measuring an elapsed time after switching the connection from the exhaust pipe to the alternative gas introduction pipe of the concentration detection unit;
A detection data storage unit that sequentially stores instantaneous concentration values detected by the concentration detection unit after switching the connection of the concentration detection unit from the exhaust pipe to the alternative gas introduction pipe;
Based on the moving average acquisition time, a moving average value calculation unit that sequentially calculates a concentration moving average value using the instantaneous concentration value stored in the detection data storage unit;
Each time the moving average value calculation unit calculates the concentration moving average value, the value obtained by subtracting the moving average acquisition time from the measurement value obtained by the time measurement unit is compared with the correction start time, and the subtracted value is A correction timing detection unit that outputs a correction start signal when the correction start time is exceeded;
When the correction start signal is output from the correction timing detection unit, the density moving average value calculated by the moving average value calculation unit is compared with the density threshold value, and the density moving average value exceeds the density threshold value. And a zero point correction unit that performs zero point correction of the concentration detection unit .

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