Gas analyzer calibration method, gas analyzer pressure correcting method, gas analyzer inspection method, pressure variation method, pressure variation apparatus, and gas analysis system

Abstract

The present invention enables accurate calculation of a pressure correction coefficient while reproducing the pressurized state in a gas analyzer, and involves: connecting, to a sample gas introduction port P1 and a gas discharge port P2 of a gas analyzer 2, a pressure variation apparatus 3 having a pressurizing mechanism 31 and a gas discharge mechanism 32; varying the pressure at the sample gas introduction port P1 and at the gas discharge port P2 by the pressurizing mechanism 31 of the pressure variation apparatus 3; introducing, in the pressure varied state, a calibration gas from a calibration gas introduction port P0 of the gas analyzer 2, and causing the calibration gas flowing out of the sample gas introduction port P1 or the gas discharge port P2 to be discharged by means of the gas discharge mechanism 32 of the pressure variation apparatus 3; and calculating the pressure correction coefficient of the gas analyzer 2 by using measurement results of the gas analyzer 3 on the calibration gas.

Description

Gas analyzer calibration method, gas analyzer pressure correction method, gas analyzer inspection method, pressure fluctuation method, pressure fluctuation device, and gas analysis system

[0001] The present invention relates to a method for calibrating a gas analyzer, a method for pressure correction in a gas analyzer, a method for inspecting a gas analyzer, a pressure fluctuation method, a pressure fluctuation device, and a gas analysis system.

[0002] In recent years, vehicle-mounted exhaust gas analyzers have been used to analyze the components of exhaust gas emitted from vehicles traveling on the road and to perform vehicle tests. Ｘ ), carbon monoxide (CO), carbon dioxide (CO ２ It has an analyzer for analyzing components such as

[0003] The measurement values ​​of each analyzer installed in this exhaust gas analyzer are affected by pressure due to changes in atmospheric pressure caused by altitude changes while driving on the road, etc. Therefore, the exhaust gas analyzer performs pressure correction on the measurement values ​​of each analyzer by using a pressure correction coefficient to correct for the pressure effect, and calculates the concentration of each component converted to a reference pressure (for example, the pressure when the calibration curve was created).

[0004] A method for calculating the pressure correction coefficient used in this exhaust gas analyzer is disclosed in Patent Document 1, which describes a method for calibrating a gas analyzer. In this method, a pressure fluctuation device is connected to a sample gas inlet port and a gas outlet port, and the sample gas inlet port and gas outlet port are depressurized by the pressure fluctuation device. In this depressurized state, calibration gas is introduced through the calibration gas inlet port, and the pressure correction coefficient of the gas analyzer is calculated using the measurement results of the calibration gas. This is done while the exhaust gas analyzer is operating in the same state as when it is installed in a vehicle, that is, with the exhaust pump operating to continuously flow calibration gas to each analyzer and various sensors operating.

[0005] JP 2019-86371 A

[0006] However, when the pressure correction coefficient obtained using the above-described method for calibrating a gas analyzer is used, the measurement results at an altitude lower than the calibration point are corrected by extrapolation under the assumption that the pressure effect is the same at altitudes lower than the calibration point. This may result in discrepancies with the actual measurement results at lower altitudes.

[0007] Furthermore, Patent Document 1 states that the sample gas inlet port and the gas outlet port are pressurized, and in this pressurized state, a calibration gas is introduced from the calibration gas inlet port, and the measurement results of the calibration gas are used to calculate the pressure correction coefficient of the gas analyzer, but does not disclose any specific configuration.

[0008] Therefore, in order to calibrate the gas analyzer under pressure, as described in Prior Art Document 1, it is necessary to bring the exhaust gas analyzer into a pressurized test chamber and perform the calibration work.

[0009] The present invention has been made to solve the above problems, and its main object is to accurately determine the pressure correction coefficient while reproducing a pressurized state for a gas analyzer without preparing an environmental facility such as a pressure test chamber.

[0010] That is, the method for calibrating a gas analyzer according to the present invention is characterized in that a pressure fluctuation device having a pressurizing mechanism and a gas exhaust mechanism is connected to a sample gas inlet port and a gas exhaust port of the gas analyzer, the pressurizing mechanism of the pressure fluctuation device applies pressure to the sample gas inlet port and the gas exhaust port to fluctuate the pressure at the sample gas inlet port and the gas exhaust port, and in a pressure-fluctuated state (specifically, a state in which pressure is applied compared to before the pressurizing mechanism is operated), a calibration gas is introduced from the calibration gas inlet port of the gas analyzer while the calibration gas flowing out from the sample gas inlet port or the gas exhaust port is exhausted by the gas exhaust mechanism of the pressure fluctuation device, and a pressure correction coefficient of the gas analyzer is calculated using the measurement results of the calibration gas in the gas analyzer.

[0011] According to the present invention, since the pressure fluctuation device is connected to the sample gas inlet port and the gas outlet port of the gas analyzer, it is possible to reproduce a pressurized state for the gas analyzer without using a pressure test chamber. Therefore, at altitudes lower than the calibration point, the pressure correction coefficient can be calculated with high accuracy without extrapolating the pressure correction coefficient.

[0012] In order to accurately determine the pressure correction coefficient, it is desirable to vary the pressure to a plurality of pressures using the pressure variation device and calculate the pressure correction coefficient of the gas analyzer so that the measurement results of the calibration gas at each of the plurality of pressures coincide with the measurement results of the calibration gas at the reference pressure. The reference pressure may be the pressure used to create the calibration curve of the gas analyzer or the pressure used during calibration such as zero calibration or span calibration.

[0013] It is desirable to introduce an excess amount of calibration gas through the calibration gas inlet port and measure the calibration gas while allowing the calibration gas to overflow from the sample gas inlet port. With this configuration, the calibration gas can be introduced into the analyzer of the gas analyzer without being diluted.

[0014] Some conventional gas analyzers further include an atmosphere inlet port. The atmosphere introduced through the atmosphere inlet port is considered to be used for gas dilution or ozone generation. The ozone generated from the atmosphere is used for analyzer measurements. The analyzer in this case may be a nitrogen oxide analyzer using the chemiluminescence (CLD) method, which utilizes an oxidation reaction caused by ozone gas. Even in this case, the measurement results of the gas analyzer may be affected by pressure fluctuations due to air pressure fluctuations via the atmosphere inlet port. Therefore, the calibration method for a gas analyzer of the present invention preferably involves connecting the pump to the atmosphere inlet port and applying pressure to the sample gas inlet port, the gas exhaust port, and the atmosphere inlet port to fluctuate the pressures of the sample gas inlet port, the gas exhaust port, and the atmosphere inlet port. Since the calibration gas is exhausted through the gas exhaust mechanism of the pressure fluctuation device, backflow of the calibration gas at the atmosphere inlet port can be suppressed.

[0015] If the gas analyzer is an on-board type, the effect of the present invention can be made more pronounced since atmospheric pressure fluctuations are likely to occur depending on the driving route during the road test.

[0016] Furthermore, the pressure correction method for a gas analyzer according to the present invention is characterized in that the measurement result of an actual measurement of the gas analyzer is corrected to the measurement result at the reference pressure of the gas analyzer based on the pressure at the time of the actual measurement, using the pressure correction coefficient obtained by the above-described calibration method.

[0017] Furthermore, a method for inspecting a gas analyzer according to the present invention is characterized in that a pressure fluctuation device having a pressurizing mechanism and a gas exhaust mechanism is connected to a sample gas inlet port and a gas exhaust port of a gas analyzer having a pressure correction function using a pressure correction coefficient, the pressurizing mechanism of the pressure fluctuation device applies pressure to the sample gas inlet port and the gas exhaust port to fluctuate the pressure at the sample gas inlet port and the gas exhaust port, and in a pressure-fluctuated state (specifically, a state in which pressure is applied compared to before the pressurizing mechanism is operated), a calibration gas is introduced from the calibration gas inlet port of the gas analyzer while the calibration gas flowing out from the sample gas inlet port or the gas exhaust port is exhausted by the gas exhaust mechanism of the pressure fluctuation device, and a measurement value corrected using the pressure correction coefficient in the gas analyzer is compared with a known concentration of the calibration gas at a reference pressure.

[0018] Furthermore, the pressure fluctuation method according to the present invention is characterized in that a pressure fluctuation device having a pressurizing mechanism and a gas exhaust mechanism is connected to a sample gas inlet port and a gas exhaust port of a gas analyzer, and the pressurizing mechanism of the pressure fluctuation device applies pressure to the sample gas inlet port and the gas exhaust port, fluctuating the pressure at the sample gas inlet port and the gas exhaust port to fluctuate the pressure of the gas analyzer, while the gas flowing out from the sample gas inlet port or the gas exhaust port is exhausted by the gas exhaust mechanism of the pressure fluctuation device.

[0019] Furthermore, the pressure fluctuation device of the present invention is a pressure fluctuation device that fluctuates the pressure of a gas analyzer, and is characterized by comprising: a first flow path connected to a sample gas inlet port of the gas analyzer; a second flow path connected to a gas exhaust port of the gas analyzer; a pressurizing mechanism that applies pressure to the sample gas inlet port and the gas exhaust port via the first flow path and the second flow path, thereby fluctuating the pressure of the sample gas inlet port and the gas exhaust port; and a gas exhaust mechanism that is connected to the flow path between the pressurizing mechanism and the sample gas inlet port, and the flow path between the pressurizing mechanism and the gas exhaust port, and that exhausts gas flowing out from the sample gas inlet port or the gas exhaust port.

[0020] In order to reproduce a pressurized state for the gas analyzer via the first and second flow paths by a common pressurization source, the pressurization mechanism preferably includes a confluent flow path to which the first and second flow paths are connected, and a pressurization source that pressurizes the first and second flow paths via the confluent flow path. Here, in order to easily adjust the pressure of each flow path, the pressurization mechanism preferably includes a pressure adjustment unit that adjusts the pressure of the confluent flow path.

[0021] In a specific embodiment of the pressurizing mechanism, it is desirable that the junction flow path has a buffer tank, the pressurization source is a pump, and the first flow path and the second flow path are connected to the pump via the buffer tank. Here, since the first flow path and the second flow path are connected to the pump via the buffer tank, it is possible to reproduce a pressurized state for the gas analyzer while reducing pump pulsation.

[0022] As a device configuration that can not only place the gas analyzer in a pressurized state but also in a depressurized state, it is desirable that the pressure fluctuation device further include a depressurization mechanism that depressurizes the sample gas introduction port and the gas discharge port via the first flow path and the second flow path, and a switching mechanism that switches between a pressurized state by the pressurization mechanism and a depressurized state by the depressurization mechanism.

[0023] It is desirable that the pressure fluctuation device of the present invention further include a control unit that controls the switching mechanism to automatically switch between the pressurized state and the depressurized state.

[0024] In order to simplify the device configuration by standardizing the configuration of the gas exhaust mechanism and the pressure reduction mechanism, it is desirable that the gas exhaust mechanism has a suction pump and that the pressure reduction mechanism is configured using the suction pump.

[0025] As described above, some gas analyzers have an atmosphere introduction port. In this case, it is preferable that the pressure fluctuation device further includes a third flow path connected to the atmosphere introduction port of the gas analyzer, and that the pressurizing mechanism applies pressure to the atmosphere introduction port via the third flow path to fluctuate the pressure at the atmosphere introduction port.

[0026] Furthermore, a gas analysis system according to the present invention is characterized by comprising a gas analyzer that analyzes a measurement target component in a sample gas, and the pressure fluctuation device described above.

[0027] According to the present invention as described above, it is possible to accurately determine the pressure correction coefficient while reproducing the pressurized state of the gas analyzer.

[0028] FIG. 1 is an overall schematic diagram of an exhaust gas analysis system according to one embodiment of the present invention. FIG. 2 is a schematic diagram showing the flow of air from an atmosphere introduction port of the exhaust gas analysis system according to the same embodiment. FIG. 3 is a schematic diagram showing the flow of air from an atmosphere introduction port of the exhaust gas analysis system according to the same embodiment. FIG. 4 is a flowchart of a calibration method according to the same embodiment. FIG. 5 is a schematic diagram showing the configuration of a pressure fluctuation device of a modified embodiment. FIG. 6 is a schematic diagram showing the configuration of a pressure fluctuation device of a modified embodiment. FIG. 7 is an overall schematic diagram of an exhaust gas analysis system according to a modified embodiment.

[0029] An exhaust gas analysis system 100 according to one embodiment of the present invention will be described below with reference to the drawings.

[0030] As shown in FIG. 1, the exhaust gas analysis system 100 of this embodiment includes an on-board exhaust gas analyzer 2 that is mounted on a vehicle, and a pressure fluctuation device 3 that is connected to the exhaust gas analyzer 2 and is used to calculate the pressure correction coefficient of the exhaust gas analyzer 2.

[0031] In addition, although not shown, the exhaust gas analysis system 100 is equipped with an exhaust gas collection mechanism such as a sampling tube that collects all or part of the exhaust gas emitted from an exhaust pipe connected to the vehicle's internal combustion engine (engine), a heating tube that introduces the exhaust gas collected by the exhaust gas collection mechanism into the exhaust gas analyzer 2 while heating or maintaining the exhaust gas at a predetermined temperature, and a power source that supplies power to the exhaust gas analyzer 2 and the heating tube.

[0032] <Exhaust Gas Analyzer 2> The exhaust gas analyzer 2 analyzes, for example, carbon monoxide (CO), carbon dioxide (CO ２ ), nitrogen oxides (NO Ｘ ), methane (CH ４ In this embodiment, the measurement target components such as CO, CO ２ Analyzer 21 and NO Ｘ The analyzer 22 and the NO analyzer 23 are provided.

[0033] The CO ２ The analyzer 21 continuously measures the concentration of carbon monoxide or carbon dioxide contained in the exhaust gas by a non-dispersive infrared (NDIR) method. Ｘ The analyzer 22 measures NO in the exhaust gas. Ｘ The NO analyzer 23 also continuously measures the concentration of NO by a chemiluminescence (CLD) method. Ｘ Like the analyzer 22, the analyzer 2 continuously measures the concentration of NO in the exhaust gas by the CLD method. In addition, the exhaust gas analyzer 2 can be equipped with various analyzers depending on the components to be measured. For example, ４In the case of measuring total hydrocarbons (THC), an analyzer using a flame ionization (FID) method is provided. In the case of measuring the number of solid particles (PN) in the exhaust gas, a condensation particle counter (CPC) is provided. The analytical data obtained by these analyzers 21 to 23 is output to an information processing unit 4, which processes, records, or displays the analytical data. Furthermore, the above-mentioned multiple analyzers may be provided separately.

[0034] Here, the information processing unit 4 is a dedicated or general-purpose computer having a CPU, internal memory, AD converter, input / output inverter, etc., and acquires, processes, records, or displays not only the analysis data from the analyzers 21 to 23 but also data from other sensors. Here, the sensors include an air-fuel ratio sensor that measures the air-fuel ratio (A / F) of the vehicle, a flow meter that measures the flow rate of exhaust gas emitted from the exhaust pipe, a GPS sensor that detects the position of the vehicle, a temperature sensor that measures the temperature outside the vehicle, a humidity sensor that measures the humidity outside the vehicle, and a pressure sensor that measures the pressure (atmospheric pressure) outside the vehicle.

[0035] The exhaust gas analyzer 2 includes CO ２ Analyzer 21, NO Ｘ The exhaust gas analyzer 2 is provided with a sample gas inlet port P1 for introducing exhaust gas into the analyzer 22 and the NO analyzer 23, and a gas outlet port P2 for discharging exhaust gas that has passed through the analyzers 21 to 23. Ｘ An ozone generator 24 is provided to generate ozone gas used in the analyzer 22 and the NO analyzer 23, and an air introduction port P3 is provided to introduce air into the ozone generator 24. That is, in this embodiment, the ports that are open to the atmosphere and are affected by pressure fluctuations are the sample gas introduction port P1, the gas discharge port P2, and the air introduction port P3.

[0036] The sample gas introduction port P1 is connected to the upstream end of the main flow path L1 through which the exhaust gas flows. ２ Analyzer 21, NO ＸAn analyzer 22 and an NO analyzer 23 are provided. A gas discharge port P2 is connected to the downstream end of the main flow path L1.

[0037] In addition, in the main flow path L1, CO ２ Analyzer 21, NO Ｘ A suction pump 25 is provided downstream of the analyzer 22 and the NO analyzer 23. The suction pump 25 allows the exhaust gas to be collected by the exhaust gas collection mechanism and introduced into the main flow path L1 from the sample gas introduction port P1, where it is measured by each of the analyzers 21 to 23. The suction pump 25 also allows the CO and CO ２ Analyzer 21, NO Ｘ The analyzer 22 and the NO analyzer 23 perform analysis under reduced pressure conditions.

[0038] In this embodiment, the main flow path L1 branches into flow paths L11 to L13 corresponding to the analyzers 21 to 23, and the analyzers 21 to 23 are connected in parallel, and the flow paths merge upstream of the suction pump 25. Each of the branch paths L11 to L13 is provided with a constant flow rate device CP1 to CP3 such as a capillary for maintaining a constant flow rate of the exhaust gas flowing into each of the analyzers 21 to 23. Here, in the main flow path L1, CO and CO are introduced from a sample gas introduction port P1. ２ Flow path to analyzer 21 and CO / CO ２ The analyzer 21 is heated to a predetermined temperature (for example, 95° C.) by a heating block 26 so that moisture in the exhaust gas does not condense. Ｘ In the branch path L12 where the analyzer 22 is provided, NO Ｘ Upstream of the analyzer 22, NO Ｘ The converter catalyst 27 is heated to a predetermined temperature (for example, 210° C.) by a heating block 28.

[0039] A calibration gas flow path L2 having a calibration gas inlet port P0 for introducing a calibration gas of known concentration is connected to the main flow path L1 upstream of each of the analyzers 21 to 23 (upstream of the branching point). The calibration gas flow path L2 is connected to a calibration gas cylinder (not shown). The calibration gas flow path L2 is also provided with an electromagnetic on-off valve V1 for switching on and off the supply of calibration gas to the main flow path L1. The electromagnetic on-off valve V1 is controlled by a valve control unit in the information processing unit 4.

[0040] The upstream end of an air introduction passage L3 is connected to the air introduction port P3, and the downstream end of the air introduction passage L3 is connected to an ozone generator 24. The ozone gas generated by the ozone generator 24 is mixed with the NO Ｘ The NO analyzer 22 and the NO analyzer 23 are connected to each other through an ozone gas flow path L4. Ｘ The gas is introduced into an analyzer 22 and an NO analyzer 23 .

[0041] 2, the ozone gas flow path L4 is provided with a constant flow rate device CP4 such as a capillary for keeping the flow rate of the ozone gas constant. Ｘ A branch flow path L5 is connected upstream of the analyzer 22 and the NOx analyzer 23, and introduces atmospheric air to dilute the exhaust gas. A constant flow rate controller CP5, such as a capillary, is provided in the branch flow path L5 to maintain a constant flow rate of atmospheric air. The pressure of the ozone generator 24 is adjusted by a pressure regulating valve V2 to a predetermined pressure such that it is a first pressure (e.g., −20 kPa) relative to the pressure of the atmospheric air inlet port P3. The pressure of the analyzers 22 and 23 is adjusted by an electromagnetic proportional valve V3 and a constant flow rate controller CP4 to a predetermined pressure such that it is a second pressure (e.g., −40 kPa) relative to the pressure of the atmospheric air inlet port P3. Furthermore, the pressure downstream of the constant flow rate controller CP2 (the analyzers 22 and 23) is adjusted by the electromagnetic proportional valve V3 and the constant flow rate controller CP5 to a predetermined pressure such that it is a second pressure (e.g., −40 kPa) relative to the pressure of the atmospheric air inlet port P3. In this way, a constant flow rate of ozone gas is supplied to the analyzers 22 and 23, and a constant flow rate of dilution air is supplied to the main flow path L1.

[0042] As shown in FIG. 3, the air intake passage L3 is Ｘ The air intake passage L3 also has a constant flow rate function for supplying a constant flow rate of exhaust gas to the analyzer 22 and the NOx analyzer 23. Specifically, the air intake passage L3 has a constant flow rate function for supplying a constant flow rate of exhaust gas to the analyzer 22 and the NOx analyzer 23. Ｘ A connecting flow path L6 is connected to the downstream side of the analyzer 22 and the NO analyzer 23 and the upstream side of the suction pump 25. In this embodiment, the connecting flow path L6 is a common flow path with a part of the branch flow path L13. A pressure regulating valve V2 is provided upstream of the connection point of the connecting flow path L6 in the atmosphere introduction flow path L3 (upstream of the constant flow controller CP1), and an electromagnetic proportional valve V3 is provided in a bypass flow path L7 connecting the connecting flow path L6 and the atmosphere introduction flow path L3. The pressure regulating valve V2 references the input pressure upstream of the constant flow controller CP2 in the main flow path L1 and adjusts the input pressure to a predetermined first pressure (e.g., −20 kPa) relative to the input pressure. Furthermore, the electromagnetic proportional valve V3 references the input pressure upstream of the constant flow rate controller CP2 in the main flow path L1 and the output pressure downstream of the electromagnetic proportional valve V3 in the connection flow path L6, and adjusts the output pressure downstream of the electromagnetic proportional valve V3 (the pressure in the buffer tank BT) to a predetermined pressure so that it becomes a second pressure (for example, -40 kPa) relative to the input pressure. In other words, the pressure regulating valve V2 and the constant flow rate controller CP1 reduce the pressure in the buffer tank BT to a predetermined pressure so that it becomes a second pressure (for example, -40 kPa) relative to the pressure at the atmosphere inlet port P3. In this way, the pressure regulating valve V2 and the electromagnetic proportional valve V3 maintain a constant pressure difference (-20 kPa) between the upstream and downstream pressures of the constant flow rate controllers CP1 to CP3 provided in each of the branch paths L11 to L13, thereby reducing CO2 and CO2. ２ Analyzer 21, NO Ｘ A constant flow rate of exhaust gas can be supplied to the analyzer 21 and the NOx analyzer 22. Note that it is sufficient if either the pressure regulating valve V2 or the electromagnetic proportional valve V3 is provided. The pressure regulating valve V2 may also be replaced with an electromagnetic proportional valve.

[0043] <Pressure Fluctuation Device 3> The pressure fluctuation device 3 is used when calibrating the above-described exhaust gas analyzer 2, specifically when determining a pressure correction coefficient of the exhaust gas analyzer 2. Note that the pressure correction coefficient in this embodiment is determined by calculating the pressure correction coefficient for CO and CO ２The CO concentration obtained by the analyzer 21, CO ２ Coefficient for correcting pressure fluctuations in concentration, NO Ｘ NO obtained by the analyzer 22 Ｘ The pressure correction coefficient is a coefficient for correcting pressure fluctuations in the concentration, and a coefficient for correcting pressure fluctuations in the NO concentration obtained by the NO analyzer 23. Specifically, the pressure correction coefficient is a coefficient for converting these concentrations into a reference pressure (the pressure at the time of creating the calibration curve in this embodiment).

[0044] The pressure fluctuation device 3 pressurizes a plurality of ports P1 to P3 of the exhaust gas analyzer 2 that are open to the atmosphere.

[0045] Specifically, as shown in Figures 1 to 3, the pressure fluctuation device 3 includes a first flow path 3L1 having one end connected to the sample gas introduction port P1, a second flow path 3L2 having one end connected to the gas discharge port P2 of the exhaust gas analyzer 2, a third flow path 3L3 having one end connected to the atmosphere introduction port P3 of the exhaust gas analyzer 2, a pressurizing mechanism 31 that applies pressure to the sample gas introduction port P1, the gas discharge port P2, and the atmosphere introduction port P3 via these flow paths 3L1 to 3L3, thereby fluctuating the pressure at the sample gas introduction port P1, the gas discharge port P2, and the atmosphere introduction port P3, and a gas discharge mechanism 32 that discharges gas flowing out from the sample gas introduction port P1 or the gas discharge port P2.

[0046] The pressurizing mechanism 31 has a confluent flow path 311 to which the first to third flow paths 3L1 to 3L3 are connected, a pressure source 312 that pressurizes the first to third flow paths 3L1 to 3L3 via the confluent flow path 311, and a pressure adjustment unit 313 that adjusts the pressure of the confluent flow path 311.

[0047] The confluence flow path 311 has a buffer tank 311a to which the other ends of the first flow path 3L1 and the second flow path 3L2 are connected, and a connection flow path 311b that connects the buffer tank 311a and the pressure source 312. The other end of the third flow path 3L3 is also connected to the connection flow path 311b.

[0048] The pressure source 312 is a pressure pump, and the pressure pump 312 pressurizes the buffer tank 311a via the connecting flow path 311b, pressurizing the first flow path 3L1 and the second flow path 3L2 connected to the buffer tank 311a, and pressurizing the third flow path 3L3 connected to the connecting flow path 311b.

[0049] The pressure adjusting unit 313 is connected to the connection flow path 311b and is configured using, for example, a pressure adjusting valve or a needle valve. The pressure adjusting unit 313 adjusts the pressure by exhausting part of the air flowing through the connection flow path 311b. The pressurizing mechanism 31 also has a pressure sensor (for example, a gauge pressure sensor 314) that detects the pressure inside the flow path of the exhaust gas analyzer 2 or the pressure inside the buffer tank 311a.

[0050] The gas exhaust mechanism 32 is connected to the flow path between the pressurizing mechanism 31 and the sample gas introduction port P1, the flow path between the pressurizing mechanism 31 and the gas exhaust port P2, and the flow path between the pressurizing mechanism 31 and the atmosphere introduction port P3, and exhausts gas flowing out from the sample gas introduction port P1 or the gas exhaust port P2.

[0051] Specifically, the gas exhaust mechanism 32 has an exhaust flow path 321 connected to the junction flow path 311 and a suction pump 322 provided in the exhaust flow path 321. In this embodiment, the exhaust flow path 321 is connected to a buffer tank 311a. The exhaust flow path 321 is also provided with a flow rate adjuster 323 such as a needle valve. The flow rate adjuster 323 adjusts the exhaust flow rate by the suction pump 322.

[0052] In addition, the pressure fluctuation device 3 of this embodiment is equipped with a pressure reduction mechanism 33 that reduces the pressure at the sample gas introduction port P1, the gas exhaust port P2, and the atmosphere introduction port P3 via the first to third flow paths 3L1 to 3L3, and a switching mechanism 34 that switches between a pressurized state by the pressurizing mechanism 31 and a reduced pressure state by the pressure reduction mechanism 33.

[0053] The pressure reducing mechanism 33 is configured using a portion of the configuration of the pressurizing mechanism 31 and the gas exhaust mechanism 32. Specifically, the pressure reducing mechanism 33 is configured using the suction pump 322 of the gas exhaust mechanism 32. The pressure reducing mechanism 33 is connected to the connection flow path 311b and has an atmosphere introduction path 331 for introducing atmosphere. The atmosphere introduction path 331 is provided with a pressure adjusting unit 332 such as a pressure adjustment valve. The pressure adjusting unit 332 adjusts the pressures in the first flow path L31, the second flow path 3L2, and the third flow path 3L3 to be constant during pressure reduction.

[0054] The switching mechanism 34 connects the pressurizing pump 312 to the buffer tank 311a when the pressurizing mechanism 31 is operating, and connects the atmosphere introduction path 331 to the buffer tank 311a when the decompression mechanism 33 is operating. The switching mechanism 34 in this embodiment is configured with a three-way valve provided at the connection point between the connection flow path 311b and the atmosphere introduction path 331. Note that the switching mechanism 34 may also be configured by providing an on-off valve in the connection flow path 311b on the pressurizing pump 312 side of the connection point with the atmosphere introduction path 331, and by providing an on-off valve in the atmosphere introduction path 331 and controlling the opening and closing of these on-off valves.

[0055] In the pressure fluctuation device 3 of this embodiment, fluid devices including the pressurizing mechanism 31, gas exhaust mechanism 32, decompression mechanism 33, and switching mechanism 34 are housed in a housing 35. Connection pipes that form part of the first flow path 3L1, second flow path 3L2, and third flow path 3L3 are connected to connection ports P4 to P6 provided in the housing 35. By connecting the housing 35 and the exhaust gas analyzer 2 via the connection pipes in this way, it is possible to easily connect the exhaust gas analyzer 2 and the pressure fluctuation device 3.

[0056] <Pressurization Operation> The pressure pump 312 is connected to the buffer tank 311a by the switching mechanism 34. In this state, when the suction pump 25 of the exhaust gas analyzer 2 and the pressure pump 312 and suction pump 322 of the pressure fluctuation device 3 are operated to supply the calibration gas from the calibration gas flow path L2, the gas flows as follows.

[0057] That is, the suction pump 25 of the exhaust gas analyzer 2 supplies the calibration gas from the calibration gas flow path L2 to each of the analyzers 21 to 23. Here, a portion of the calibration gas flows out from the sample gas inlet port P1, and the calibration gas that has passed through each of the analyzers 21 to 23 flows out from the gas outlet port P2. The sample gas inlet port P1 and the gas outlet port P2 are pressurized by the pressurizing mechanism 31 (a state in which more pressure is applied compared to before the pressurizing mechanism 31 was activated). Furthermore, air is introduced from the third flow path 3L3 to the air inlet port P3 of the exhaust gas analyzer 2 via the pressurizing pump 312. Here, the calibration gas flowing into the buffer tank 311a is discharged to the outside by the gas exhaust mechanism 32, so that the calibration gas can be prevented from flowing back into the sample gas inlet port P1 and the gas outlet port, and from flowing into the third flow path 3L3. As a result, calibration gas is supplied to each analyzer 21 to 23 with the sample gas inlet port P1, gas outlet port P2, and atmosphere inlet port P3 pressurized (a state in which more pressure is applied compared to before the pressurization mechanism 31 was operated).

[0058] <Decompression Operation> The atmosphere introduction path 331 is connected to the buffer tank 311a by the switching mechanism 34. In this state, when the suction pump 25 of the exhaust gas analyzer 2 and the suction pump 322 of the pressure fluctuation device 3 are operated to supply the calibration gas from the calibration gas flow path L2, the gas flows as follows.

[0059] That is, the calibration gas is supplied from the calibration gas flow path L2 to each of the analyzers 21 to 23 by the suction pump 25 of the exhaust gas analyzer 2. Here, the calibration gas is sucked from the sample gas inlet port P1 via the first flow path 3L1. Also, the atmosphere is introduced from the third flow path 3L3 to the atmosphere introduction port P3 of the exhaust gas analyzer 2 via the suction pump 322. Here, because the third flow path 3L3 is connected to the atmosphere introduction path 331, there is no risk of the calibration gas flowing into the buffer tank 311a via the first flow path 3L1 and the second flow path 3L2 flowing into the third flow path 3L3. As a result, the calibration gas is supplied to each of the analyzers 21 to 23 with the sample gas inlet port P1, the gas outlet port P2, and the atmosphere introduction port P3 depressurized.

[0060] <Calibration Method (Method for Calculating Pressure Correction Coefficient)> Next, a method for calculating a pressure correction coefficient using the pressure fluctuation device 3 configured as described above will be described with reference to Fig. 4. The calibration method of this embodiment involves reproducing a pressurized state for the exhaust gas analyzer 2, and calculating the pressure correction coefficient for the exhaust gas analyzer 2 in addition to zero-span calibration of the exhaust gas analyzer 2. The calibration method may also include creating a calibration curve.

[0061] First, the exhaust gas analyzer 2 to be calibrated is prepared. At this time, if the exhaust gas analyzer 2 is mounted on a vehicle, it may be in a mounted state or may be removed from the vehicle.

[0062] Then, the exhaust gas analyzer 2 is warmed up (step S1). At this time, the suction pump 25 of the exhaust gas analyzer 2 is running. If the exhaust gas analyzer 2 has a pressure correction function, the pressure correction function is turned off.

[0063] After warm-up, zero calibration is performed by flowing calibration gas for zero calibration into the exhaust gas analyzer 2 under atmospheric pressure. Furthermore, span calibration is performed by flowing calibration gas into the exhaust gas analyzer 2 (step S2). These calibration gases are supplied from the calibration gas flow path L2. At this time, the pressure fluctuation device 3 is in a stopped state.

[0064] Thereafter, the flow paths 3L1 to 3L3 of the pressure fluctuation device 3 are connected to the ports P1 to P3 of the exhaust gas analyzer 2. In this state, the pressurizing mechanism (pressurizing pump) and gas exhaust mechanism (suction pump) of the pressure fluctuation device 3 are activated (step S3).

[0065] Here, the pressure in the buffer tank 311a (the pressure of the gauge pressure sensor 314) is adjusted to a constant value (e.g., atmospheric pressure conditions of 0 m to 1500 m) by the pressure adjusting unit 313 of the pressurizing mechanism 31 or the flow rate adjusting unit 323 of the gas exhaust mechanism 32 (step S4). For example, if the exhaust gas analyzer 2 is set to an altitude of 1500 m, the atmospheric pressure conditions may be gradually increased to lower altitudes, such as 1500 m, 1000 m, 500 m, 0 m, 500 m, 1000 m, and 1500 m. After the atmospheric pressure conditions are set to the predetermined minimum altitude, the altitude may be gradually increased again. Here, the pressure adjusting unit 313 or the flow rate adjusting unit 323 is operated with reference to the measurement value of the gauge pressure sensor 314 of the pressure fluctuation device 3 to control the pressure to the desired value. This operation may be automatically controlled by a computer or manually performed by an operator.

[0066] Under each atmospheric pressure condition, calibration gas for zero calibration and calibration gas for span calibration are respectively flowed, and measurements are performed by each analyzer 21-23 (step S5). These calibration gases are flowed from the calibration gas flow path L2 into the main flow path L1. At this time, an excess amount of calibration gas is supplied so that it flows not only downstream (gas outlet port P2) from the connection point but also upstream (sample gas inlet port P1). In other words, calibration gas flows from the sample gas inlet port P1 into the first flow path 3L1. This allows pure calibration gas to flow into each analyzer 21-23. If calibration gas does not flow back from the sample gas inlet port P1, atmospheric air would be introduced through the sample gas inlet port P1, diluting the calibration gas and preventing accurate calibration. Note that an excess amount means that the calibration gas supply flow rate is greater than the flow rate obtained by subtracting the amount introduced through the atmospheric air inlet port P3 from the amount discharged from the gas outlet port P2.

[0067] After each measurement is completed (step S6), the pressure fluctuation measurement device 3 and the exhaust gas analyzer 2 are stopped (step S7). Then, a pressure correction coefficient is calculated from the measurement results obtained from each measurement (step S8). Specifically, the pressure correction coefficient is created so that the measurement results obtained from each measurement coincide with the measurement value of the calibration gas at the reference pressure.

[0068] By varying the pressure among a plurality of pressures and obtaining the measured values ​​of the analyzers 21 to 23 at each pressure, the pressure correction coefficients of the analyzers 21 to 23 can be determined. Here, the pressure correction coefficients may be calculated by the information processing unit 4, or may be calculated manually by an operator. The pressure correction coefficients may be in the form of a table or a function. The data of the pressure correction coefficients determined in this manner is stored in the internal memory of the information processing unit 4.

[0069] By performing the above process for each calibration gas with a different concentration, the pressure correction coefficient for each concentration can be obtained. When using multiple calibration gases with different gas types, the same process can be performed for each calibration gas, or calibration can be performed using a mixed gas of multiple calibration gases.

[0070] By using this pressure correction coefficient, the information processing unit 4 corrects the pressure difference from the reference pressure (the pressure at the time of creating the calibration curve) based on the pressure obtained by the pressure sensor (not shown) during actual road driving (at the time of actual measurement) and the concentration obtained by each analyzer 21 to 23, and calculates the concentration converted to the pressure at the time of creating the calibration curve.

[0071] In the above, the procedure for determining the pressure correction coefficient by pressurizing the exhaust gas analyzer is described. However, by using not only the pressurizing mechanism but also the depressurizing mechanism and the switching mechanism, it is possible to determine the pressure correction coefficient by reproducing not only a state at an altitude lower than the calibration point but also a state at an altitude higher than the calibration point, regardless of the altitude of the calibration point.

[0072] <Effects of this Embodiment> According to the gas analysis system 100 of this embodiment, the pressure fluctuation device 3 is connected to the sample gas inlet port P1 and the gas outlet port P2 of the exhaust gas analyzer 2, so it is possible to reproduce a pressurized state for the exhaust gas analyzer 2 without using a pressurized test chamber. Therefore, at altitudes lower than the calibration point, it is possible to accurately determine the pressure correction coefficient without extrapolating the pressure correction coefficient. As a result, it is possible to accurately measure the measurement results of the exhaust gas analyzer 2 without extrapolating them.

[0073] In particular, in this embodiment, when the sample gas introduction port P1, the gas discharge port P2, and the atmosphere introduction port P3 are pressurized, the calibration gas flowing out from the sample gas introduction port P1 or the gas discharge port P2 is discharged by the gas discharge mechanism 32 of the pressure fluctuation device 3, thereby suppressing backflow of the calibration gas due to pressurization and making it possible to accurately determine the pressure correction coefficient.

[0074] <Modified Embodiment> The present invention is not limited to the above-described embodiment.

[0075] For example, the exhaust gas analysis device 2 has an air introduction flow path L3 because it has a function to dilute exhaust gas and an ozone generator, but if these functions are not provided, the device may not have an air introduction flow path.

[0076] Furthermore, it is not necessary for the atmosphere to be introduced into the atmosphere introduction port P3 and the atmosphere introduction path 3L3. For example, oxygen or ozone may be supplied from a cylinder, or other gases may be supplied.

[0077] Furthermore, as shown in FIG. 5, the pressure fluctuation device 3 may have a configuration that does not include the pressure reducing mechanism 33 and the switching mechanism 34, but only has the function of pressurizing the gas analyzer 2.

[0078] 6, as a modified example of the pressure adjusting unit 313 of the pressurizing mechanism 31 of the above embodiment, an on-off valve 315 such as a solenoid valve may be provided in the connection flow path 311b, and the pressure may be adjusted to a desired level by controlling the on-off of the on-off valve 315. Here, the on-off valve 315 is controlled to turn on and off so that the pressure detected by the gauge pressure sensor 314 becomes the target pressure, for example.

[0079] 7, a pressure vessel 316 such as a buffer tank in which gas pressurized higher than the ambient pressure is stored may be used as the pressure source 312. A compressor 317 may be connected to the pressure vessel 316. The pressure adjustment unit 313 in FIG. 7 has the same configuration as that in the above embodiment, but may also have a configuration using the on-off valve 315 shown in FIG. 6.

[0080] In the above embodiment, the data of the pressure correction coefficient is stored in the internal memory of the exhaust gas analyzer 2. However, the data of the pressure correction coefficient may be stored in the internal memory of an information processing device that is separate from the exhaust gas analyzer 2, and the information processing device may acquire the analysis data of each analyzer 21 to 23 of the exhaust gas analyzer 2 and perform pressure correction.

[0081] Furthermore, the pressure fluctuation device of the above embodiment may be configured to automatically switch between a pressurized state and a reduced-pressure state. Specifically, the pressure fluctuation device may further include a control unit that controls the switching mechanism to automatically switch between the pressurized state and the reduced-pressure state. In this case, the control unit may automatically switch between the pressurized state and the reduced-pressure state by, for example, comparing the pressure of the gauge pressure sensor 314 with a preset target pressure.

[0082] 8, the gas analyzer 2 and the pressure fluctuation device 3 can be controlled in cooperation with an external operation device 6 such as a computer to calculate the pressure correction coefficient of the gas analyzer 2. Specifically, the gas analyzer 2 is operated using the external operation device 6. The external operation device 6 starts and stops measurement by the gas analyzer 2 via a communication cable or the like. A control unit 51 (which may be the information processing unit 4) of the gas analyzer 2 controls the suction pump 25 and various valves in accordance with signals from the external operation device 6. The pressure fluctuation device 3 is also operated using the external operation device 6. The external operation device 6 starts and stops the pressure fluctuation device 3 via a communication cable or the like. A control unit 52 of the pressure fluctuation device 3 controls the pressure pump 313, the suction pump 322, and various valves 323 in accordance with signals from the external operation device 6. The external operation device 6 includes a determination unit 61 that determines whether the pressure inside the gas analyzer 2 and the pressure fluctuation device 3 is positive or negative relative to a preset target pressure. The pressure gauge referred to by the determination unit 61 may be, for example, a gauge pressure sensor 314. The external operation device 6 outputs control command signals for the pumps and the like of each device to the gas analyzer 2 and the pressure fluctuation device 3 based on the determination result of the determination unit 61 so as to achieve a preset target pressure. The function of the determination unit 61 may be provided in the control unit 51 or the control unit 52.

[0083] In the calibration method of the above embodiment, zero-span calibration (step S2) is performed, but zero-span calibration does not have to be performed.

[0084] Furthermore, the pressure correction coefficient may be created using the pressure at the time of zero-span calibration as the reference pressure in addition to the pressure at the time of creating the calibration curve.

[0085] Furthermore, a pressure fluctuation device different from that of the above embodiment may be connected to any one of the sample gas inlet port, gas outlet port, and atmosphere inlet port of the gas analyzer, and these pressure fluctuation devices may be controlled to adjust each port to the same pressure.

[0086] In addition, a pressurizing mechanism and a gas exhaust mechanism may be provided independently for each of the sample gas inlet port, the gas exhaust port, and the atmosphere inlet port of the gas analyzer. Alternatively, a gas exhaust mechanism may be provided between the pressurizing mechanism and the sample gas inlet port, between the pressurizing mechanism 31 and the gas exhaust port, and between the pressurizing mechanism and the atmosphere inlet port.

[0087] The technical concept of the pressure fluctuation device of the above embodiment can also be stated as follows. That is, the pressure fluctuation device is a pressure fluctuation device that fluctuates the pressure of a gas analyzer, and includes a first flow path connected to a sample gas inlet port of the gas analyzer, a second flow path connected to a gas outlet port of the gas analyzer, a gas discharge mechanism that discharges gas from the sample gas inlet port and the gas outlet port via the first flow path and the second flow path, and a pressurization mechanism that applies pressure to the flow path between the gas discharge mechanism and the sample gas inlet port and the flow path between the gas discharge mechanism and the gas outlet port, thereby fluctuating the pressure at the sample gas inlet port and the gas outlet port. Even with this configuration, a gas analysis system similar to that of the above embodiment can be configured.

[0088] In the above embodiment, the exhaust gas analyzer is described as being mounted on a vehicle, but it may be a stationary exhaust gas analyzer instead of being mounted on a vehicle. Furthermore, the measurement target of the exhaust gas analyzer is not limited to exhaust gas from a vehicle, but may be exhaust gas from an engine, a ship, or other moving body, or the atmosphere may be measured directly.

[0089] In the above embodiment, an exhaust gas analyzer for analyzing exhaust gas from a vehicle equipped with a gasoline engine or a diesel engine has been described, but the present invention can also be applied to fuel cell vehicles powered by fuel cells and hydrogen engine vehicles powered by burning hydrogen. By using an analyzer equipped with a QCL (Quasi-Clamp) in the analysis section, leaked hydrogen from a fuel cell exhaust gas can be measured, and unburned hydrogen that did not react in the combustion tower can be measured in the exhaust gas from a hydrogen engine.

[0090] In addition, various modifications and combinations of the embodiments may be made as long as they do not go against the spirit of the present invention.

[0091] According to the present invention, it is possible to accurately determine the pressure correction coefficient while reproducing the pressurized state of the gas analyzer.

[0092] 100: Gas analysis system 2: Exhaust gas analyzer (gas analyzer) P0: Calibration gas introduction port P1: Sample gas introduction port P2: Gas exhaust port P3: Atmospheric introduction port 3: Pressure fluctuation device 31: Pressurization mechanism 32: Gas exhaust mechanism 322: Suction pump 311: Confluent flow path 312: Pressurization source (pressurization pump) 313: Pressure adjustment unit 311a: Buffer tank 33: Pressure reduction mechanism 34: Switching mechanism

Claims

1. Connect a pressure fluctuation device having a pressurizing mechanism and a gas discharge mechanism to the sample gas introduction port and the gas discharge port of the gas analyzer, Apply pressure to the sample gas introduction port and the gas discharge port by the pressurizing mechanism of the pressure fluctuation device to vary the pressures of the sample gas introduction port and the gas discharge port, While introducing calibration gas from the calibration gas introduction port of the gas analyzer in a state where the pressure is fluctuated, discharge the calibration gas flowing out from the sample gas introduction port or the gas discharge port by the gas discharge mechanism of the pressure fluctuation device, A calibration method for a gas analyzer that calculates a pressure correction coefficient of the gas analyzer using the measurement result of the calibration gas in the gas analyzer.

2. The pressure fluctuation device is used to vary the pressure to a plurality of pressures, and the pressure correction coefficient of the gas analyzer is calculated so that the measurement results of the calibration gas at each of the plurality of pressures match the measurement result of the calibration gas at the reference pressure. The calibration method for a gas analyzer according to claim 1.

3. The calibration method for a gas analyzer according to claim 1 or 2, wherein an excessive amount of calibration gas is introduced from the calibration gas introduction port, and the calibration gas is measured while allowing the calibration gas to overflow from the sample gas introduction port.

4. The gas analyzer further includes an air introduction port, The pressure fluctuation device is connected to the air introduction port, and pressure is applied to the sample gas introduction port, the gas discharge port, and the air introduction port to vary the pressures of the sample gas introduction port, the gas discharge port, and the air introduction port. The calibration method for a gas analyzer according to claim 1 or 2.

5. The calibration method for a gas analyzer according to claim 1 or 2, wherein the gas analyzer is of a vehicle-mounted type.

6. Using the pressure correction coefficient obtained by the calibration method according to claim 1 or 2, correct the measurement result of the actual measurement of the gas analyzer to the measurement result at the reference pressure of the gas analyzer based on the pressure at the time of the actual measurement. A pressure correction method for a gas analyzer.

7. Connect a pressure fluctuation device having a pressurizing mechanism and a gas discharge mechanism to the sample gas introduction port and the gas discharge port of a gas analyzer having a pressure correction function using a pressure correction coefficient, By the pressurizing mechanism of the pressure fluctuation device, pressure is applied to the sample gas introduction port and the gas discharge port to vary the pressures of the sample gas introduction port and the gas discharge port. In a state where the pressure is fluctuated, while introducing calibration gas from the calibration gas introduction port of the gas analyzer, the calibration gas flowing out from the sample gas introduction port or the gas discharge port is discharged by the gas discharge mechanism of the pressure fluctuation device. A method for inspecting a gas analyzer, which compares a measured value corrected using the pressure correction coefficient in the gas analyzer with a known concentration at the reference pressure of the calibration gas.

8. Connect a pressure fluctuation device having a pressurizing mechanism and a gas discharge mechanism to the sample gas introduction port and the gas discharge port of the gas analyzer. A pressure fluctuation method in which, while varying the pressure of the gas analyzer by applying pressure to the sample gas introduction port and the gas discharge port by the pressurizing mechanism of the pressure fluctuation device to vary the pressures of the sample gas introduction port and the gas discharge port, the gas flowing out from the sample gas introduction port or the gas discharge port is discharged by the gas discharge mechanism of the pressure fluctuation device.

9. A pressure fluctuation device for varying the pressure of a gas analyzer, a first flow path connected to the sample gas introduction port of the gas analyzer, a second flow path connected to the gas discharge port of the gas analyzer, a pressurizing mechanism for applying pressure to the sample gas introduction port and the gas discharge port via the first flow path and the second flow path to vary the pressures of the sample gas introduction port and the gas discharge port, and a gas discharge mechanism connected to the flow path between the pressurizing mechanism and the sample gas introduction port and the flow path between the pressurizing mechanism and the gas discharge port, for discharging the gas flowing out from the sample gas introduction port or the gas discharge port.

10. The pressurizing mechanism includes a confluence flow path to which the first flow path and the second flow path are connected, a pressurizing source for pressurizing the first flow path and the second flow path via the confluence flow path, and a pressure adjustment unit for adjusting the pressure of the confluence flow path. The pressure fluctuation device according to claim 9.

11. The confluence flow path has a buffer tank, the pressurizing source is a pump, and the first flow path and the second flow path are connected to the pump via the buffer tank. The pressure fluctuation device according to claim 10.

12. A pressure reducing mechanism for reducing the pressure of the sample gas introduction port and the gas discharge port via the first flow path and the second flow path; The pressure fluctuation device according to any one of claims 9 to 11, further comprising a switching mechanism for switching between the pressurized state by the pressurizing mechanism and the depressurized state by the pressure reducing mechanism.

13. The pressure fluctuation device according to claim 12, further comprising a control unit that controls the switching mechanism to automatically switch between the pressurized state and the depressurized state.

14. The gas discharge mechanism has a suction pump, The pressure fluctuation device according to claim 12, wherein the pressure reducing mechanism is configured using the suction pump.

15. Further comprising a third flow path connected to the air introduction port of the gas analyzer, The pressure fluctuation device according to any one of claims 9 to 11, wherein the pressurizing mechanism applies pressure to the air introduction port via the third flow path to vary the pressure of the air introduction port.

16. A gas analysis system comprising a gas analyzer for analyzing a component to be measured in a sample gas; And the pressure fluctuation device according to any one of claims 9 to 11.