JP2007024730A - Apparatus and method for sampling diluted exhaust gas using laminar exhaust gas flowmeter and heating/cooling surge tube apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas proportionate sampling apparatus for accurately measuring and extracting a required exhaust sample flow rate with a total exhaust gas flow rate over a wide range of flow rates and diluting it with a clean gas. <P>SOLUTION: The total flow rate of exhaust gases is measured through the use of a laminar flowmeter immediately in the back of an exhaust pipe. An exhaust gas sample flow rate at a specific ratio to this flow rate value at all times is measured and collected in a bag while being controlled by a control valve in the sampling apparatus. The flow rate is controlled through the use of a sample exhaust gas flow of a specific flow rate using CFO or CFV and clean dry air or gaseous nitrogen of a flow rate at a specific ratio to this as a dilution gas and each CFO or CFV, drawn by suction by a dry pump, mixed, and applied with pressure to adjust a diluted exhaust gas sample of specific pressure. Part of it is collected in a bag as a controlled and diluted exhaust gas sample proportional to the total exhaust gas flow rate by a variable cross-sectional-area orifice type flow rate measuring and controlling device. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust gas sampling technique for obtaining a mass emission value of a pollutant in an exhaust gas measurement of an internal combustion engine such as an automobile, and relates to the automobile industry and the environment countermeasure industry.

  In order to measure the mass emission value of automobile exhaust gas of an internal combustion engine, a total exhaust gas flow called a CVS (Constant Volume Sampler) device is mixed with a clean dilution gas, and a diluted exhaust gas having a constant flow rate is prepared as a sample gas. The exhaust gas component is discharged in mass during a certain operating time by analyzing the collected sample gas obtained by bag sampling a part of the sample gas at a constant flow rate. An apparatus for obtaining a value has been widely used. As another device, the total exhaust gas flow rate is measured with a flow measurement device other than a laminar type flow meter such as an ultrasonic flow meter, and a part of the exhaust gas and clean diluted air are mixed to make a diluted exhaust gas proportional to the exhaust gas flow rate. For example, Bag Mini-Diluter has been proposed in which the sample flow rate is controlled by a thermal mass flow controller and bag sampling is performed as a diluted exhaust gas sample flow to obtain a mass emission value. (Refer nonpatent literature 1).

D.J.Luzenski, et al; Evaluation of Improved Bag Mini-Diluter System for Low Level Emission Measurements, SAE paper 2002-01-0047 Special table 2001-507458

  In the conventional apparatus for diluting the entire exhaust gas flow, the clean air and inert gas used for dilution require a flow rate much higher than the exhaust gas flow rate, but the concentration of the pollutant component contained therein is extremely low. Not only is there a problem in terms of cost, but there are also problems in terms of energy consumption and the increase in size of the equipment. Yes. Also, in the method of measuring the total exhaust gas flow rate with an ultrasonic flow meter etc., it is necessary to cool the total exhaust gas flow rate to a measurable temperature using a large heat exchanger etc. There is a problem. In particular, there is a serious problem that accurate measurement is difficult when the flow rate is small and the pulsation is relatively large, such as when the engine is idling. In addition, it is difficult to accurately measure and control the thermal mass flow controller used for flow rate control over a necessary flow rate range, and the temperature and responsiveness are not necessarily satisfied. In particular, the pulsation phenomenon of the exhaust gas flow in the low-speed rotation range is not only due to the mixing of the gas components before and after, but also causes the unacceptable error at a low flow rate in a wide flow range as long as 1:50 in the conventional flow measurement method. It was a big problem.

  As described above, the conventional technology has difficulty in increasing the size, energy and cost of the apparatus, but particularly when the engine operating load range is expanded and the exhaust gas flow rate reaches 1:50, the exhaust gas has pulsation. There are major difficulties in the accuracy of measurement and control when the flow rate and sample flow rate are relatively small, and solving these problems is the main issue. Furthermore, when the diluted exhaust gas has a temperature of 60 ° C. or higher, it is also important to control the flow rate with a quick response within 0.3 seconds and to ensure the synchronism between the extracted exhaust component change accompanying the change in operating conditions. It is a problem.

  According to the present invention, a newly developed laminar flow meter can be applied to exhaust gas in a wide flow range, whereas there has been no appropriate exhaust gas flow measurement device for an internal combustion engine over a wide flow range. Therefore, it is an object of the present invention to provide an exhaust proportional sampling apparatus capable of controlling the sample flow rate with an appropriate response by using such a laminar type flow meter for measuring the total flow rate of the exhaust gas and the sample gas flow rate. The laminar flow meter has a substantially linear proportional relationship between the flow rate and the measured differential pressure over a wide flow rate range, and has a feature that the flow rate can be accurately measured even for a flow with a large pulsation. Conventional laminar flowmeters are difficult to use at high temperatures exceeding 350 ° C due to changes in gas viscosity, thermal expansion, thermal deformation, etc., and the accumulation of condensed components and particles contained in exhaust gas is a major difficulty. Met. However, in recent years, laminar flow meters can be applied because gasoline engines and the like are almost free of contaminants that cause exhaust gas accumulation. Furthermore, with respect to the responsiveness important in the exhaust proportional sampling device, the laminar type flow meter can respond to the same level as the response speed of the differential pressure measurement system, that is, the ms level. However, there are factors such as dead volume of the engine exhaust system as a whole system, and in addition to the flow rate measurement, the control system and the pipe flow rate may also limit responsiveness. As an exhaust gas measurement and control system, the laminar flow meter has sufficient performance for reducing the overall response speed, which is considered necessary for following changes in operating conditions, to 0.1 to 0.3 seconds or less. is there.

  In addition, two reliable CFOs (critical flow orifices, hereinafter the same in this claim and specification) or CFVs (critical) are used to maintain a constant ratio between the exhaust gas sample and diluent gas flow rates. The inlet temperature and pressure were controlled to be constant using a flow venturi (critical flow venturi, hereinafter the same in claims and specification). Then, the diluted exhaust gas sample flow is adjusted by securing an appropriate gauge pressure by using a dry pump capable of ensuring a clean and sufficient pressure ratio. As a device for measuring the flow rate in proportion to the total exhaust gas flow rate in the diluted exhaust gas sample flow and sampling it into a bag, a variable cross-sectional area type orifice having a quick response and a wide flow rate range was used. In particular, the variable cross-sectional area orifice in this case has a characteristic that the differential pressure is substantially constant and the flow rate varies depending on the cross-sectional area of the orifice, and is characterized by high response, high accuracy, and a wide flow rate range.

  Normally, the flow rate ratio between exhaust gas and dilution gas is about 1: 1, and the mixed gas has a dew point of about 40 ° C. However, there are changes in the flow path and pressure of pumps and valves, and the pipe is kept at 60 ° C or higher. It is desirable. From the accuracy of gas analysis and other considerations, the apparatus of the present invention assumes a flow rate ratio of about 1: 1 ± 20%. The CFO or CFV flow rate will determine the maximum diluted exhaust gas sample flow rate along with the pump capacity. Of the total exhaust gas flow rate, the exhaust gas sample is usually 1/50 to 1/200. Although it depends on the measurement operation time, in many cases the sample bag capacity is about 100L.

  To measure the flow rate of engine exhaust gas, use a laminar flow meter with a heating / cooling surge tube on the upstream side to maintain the laminar inlet temperature at 100 ° C or higher even at low flow rates such as when idling. Can do. In particular, condensed water or the like often flows out immediately after the cold start of the engine, but preheating the heating surge tube can prevent inflow into the laminar flow meter. Further, when the exhaust gas is at a high temperature, effective cooling can be performed to suppress the exhaust gas temperature to about 300 ° C. or less. By using such a heating / cooling surge tube, the laminar flow meter has a flow rate measurement range of 1:50 or more, and the low-boiling point components are prevented from condensing and reliably measured. In consideration of the case where pressure and temperature distribution is uneven in the radial direction in the laminar element, a plurality of temperature measuring ends are arranged at a plurality of positions in the radial direction area average. Thereby, the area average differential pressure and temperature of the exhaust gas flowing in the laminar element can be measured, and more accurate flow rate measurement can be performed. In particular, the laminar flow meter can accurately measure the exhaust system even when the flow rate is small and the pulsation rate is large due to idling or the like.

  Various controls such as a thermal mass flow controller can be applied to the flow control of the diluted exhaust gas sample flow, but there are problems with the flow control range and responsiveness at high temperatures. The variable cross-sectional area orifice type flow measurement control device used here has a wide control range and fast response, the control system can be moved at a speed of about 0.1 to 0.2 sec, and can be applied to a temperature of 60 ° C. or higher. Since the relationship between the flow rate and the position of the control valve, that is, the position pulse, is a linear proportional relationship over a wide flow rate range at a constant differential pressure of about 10 kPa (gauge pressure), the flow rate is maintained when the pressure of the diluted exhaust gas sample is appropriately maintained by the control valve. Control becomes extremely easy.

  The use of a surge tube also has an advantage in pressure measurement when there is a large pulsation in a small flow rate range, but a larger advantage is that the exhaust gas after leaving the engine exhaust pipe is mixed before and after the exhaust gas components. It is in the point which can be suppressed. Mixing of exhaust gas before and after the components in the exhaust measurement system after the exhaust pipe outlet until sampling should be avoided as much as possible, and a surge tube that is effective at an actual volume of 1/100 or less is more suitable than a surge tank with a large capacity.

  In this device, a part of the exhaust gas measured with a laminar flow meter is extracted at a constant flow rate regardless of the operating conditions, and is cooled as a sample gas by a sample probe, and the same in a constant temperature bath (about 65 ° C). Controlled by temperature. On the other hand, the dilution gas is depressurized at the thermostatic chamber inlet, and is controlled to the same pressure by a control valve using the exhaust side pressure as a pilot pressure so as to be the same as the exhaust gas side pressure, and passes through an appropriate pipe length in the thermostatic chamber. The temperature is also controlled in the same way as the thermostatic chamber. The exhaust sample gas CFO or CFV and the dilution gas CFO or CFV are controlled to have the same inlet temperature and pressure, mixed on the outlet side, sucked below the critical pressure, and the suction pressure is monitored. It is sucked and compressed by a dry pump such as a clean scroll pump at an absolute pressure of 50 kPa or less, and discharged as a diluted exhaust gas sample stream at a pressure higher than the atmospheric pressure. This pressure is, for example, 10 kPa as a gauge pressure, and is kept constant by a control valve with a relief.

  A portion of the diluted exhaust gas sample flow that is controlled to a flow rate proportional to the total exhaust gas flow rate by the variable cross-sectional area orifice type flow rate measurement control device is fed into the sample bag. About 4 sets of sample bags are prepared in consideration of the operation mode and the like, and the flow paths are switched.

  The control signal of the variable cross-section orifice type flow rate measurement control device is a calculation delay circuit that takes into account the total exhaust gas flow rate and its estimated average temperature for a certain time, for example, about 0.8 seconds to 5.5 seconds, than the output of the total exhaust gas flow meter Is input with a delay time, and the time can be corrected so that the change time of the exhaust gas component in the variable cross-sectional area orifice type flow measurement control device substantially matches the change in the engine operating conditions.

  In summary, the diluted exhaust sampling device, the diluted exhaust sampling method, and the heating / cooling surge tube device using the laminar exhaust gas flowmeter of the present invention have the configuration described in the claims. Eggplant.

  According to the present invention, as a proportional sampling device for exhaust gas of an internal combustion engine, the exhaust gas total flow rate is accurately measured with a laminar flow meter excellent in reliability and responsiveness over a wide flow range of 1:50 or more. A part is sucked at a constant pressure and temperature with a constant flow rate controlled by CFO or CFV. The temperature is controlled so that it always becomes a constant ratio with the exhaust gas sample flow rate, and suction is performed as a constant flow rate using CFO or CFV in which the inlet pressure is controlled by a pressure reducing valve with a pilot so that the pressure also matches the exhaust gas side, Mix at the outlet of two CFO or CFV, and suck and pressurize with a scroll pump with few pulsations while monitoring the suction pressure as a diluted exhaust gas sample stream. The discharge pressure of the scroll pump has a small pulsation amplitude and does not require a buffer tank, and is accurately controlled to, for example, 10 kPa (gauge pressure) by a pressure control valve with a relief. Under this pressure and temperature conditions, the variable cross-sectional area orifice enables a high-speed response of approximately 0.2 seconds and a highly accurate flow rate control of 0.1% or less. This flow rate control matches the time when the exhaust gas component arrives at the orifice, so it responds appropriately to changes in engine operating conditions, and is not possible with other exhaust gas proportional sampling devices that do not provide time correction. Accumulated components of a diluted exhaust gas sample can be collected, and the integrated flow rate can be measured with extremely high accuracy. A device that can improve the accuracy and response speed of flow control while maintaining the synchronism of exhaust gas component change while the flow control of diluted exhaust gas is excellent in accuracy and responsiveness, which is important for the proportional sampling device. Realize. If clean dry air is used as a diluent gas that is completely unaffected by background contamination, or if it is sent from the diluted exhaust gas sample stream to the sample bag at an appropriate flow rate ratio, the exhaust will be in the range of about 1/50 to 1/200. A gas sample can be collected or obtained as an integrated flow rate value. By using a heating / cooling surge tube, it is possible to prevent the influence of pulsation of the exhaust system, to prevent the influence of condensed water at the start, and to expect favorable effects such as flow rate measurement and suppression of mixing of components before and after the exhaust gas.

  According to the present invention, it is possible to configure an exhaust gas proportional sampling device that accurately measures the required exhaust sample flow rate over a wide flow rate range together with the total exhaust gas flow rate, and extracts and dilutes the exhaust gas flow rate. In addition, it ensures proper responsiveness and simultaneous change of components, can set the temperature corresponding to the dew point of exhaust gas and diluted sample gas, and set the exhaust gas flow rate ratio and dilution ratio according to the required sample flow rate such as gas analysis There are features that can be done. Exhaust proportional sampling that can measure emission values using an exhaust laminar flow meter that can be applied to low emission engines instead of conventional CVS devices, such as small size, small capacity, high accuracy, high response and not affected by background contamination There is an effect that enables the device.

The details of the present invention will be described below with reference to the system diagram of the embodiment shown in FIG. 1 and the configuration diagram of the main elements shown in FIGS. In FIG. 1, reference numeral 11 denotes an internal combustion engine automobile, which is a total exhaust gas via a heating / cooling surge tube 30 improved from a surge tube (utility model registration No. 3085960, patent application 2002-65771) connected to the outlet of the exhaust pipe 12. Stream 4 is introduced into the exhaust laminar flow meter 20. As shown in detail in FIG. 2, the heating / cooling surge tube 30 can be heated by disposing a sheathed heater coil 33 having a capacity of 700 W or more made of stainless steel on the inner periphery of a central pipe line 32, A temperature sensor 34 for stopping and controlling heating at a pipe temperature of about 200 ° C. is disposed in the vicinity. A rubber thin-film tube 35 with an O-ring, which is a main component of the heating / cooling surge tube 30, is made of, for example, silicone rubber and is hermetically held by flanges 36 and 37 on both sides and expands and contracts according to internal pressure. The protective tube 39 is made of aluminum or the like having good heat conductivity, and its vent holes 38 are provided in large numbers so that the surface area can be increased, so that the opening area ratio is 35% or more. With such a structure, when the exhaust gas flow rate is 0 or 0.18 m ³ / min or less, the exhaust gas is heated to 100 ° C. or higher, and the exhaust gas temperature can be 150 ° C. or higher when the engine is started or idle. Further, when the exhaust gas inlet temperature is 250 ° C. or higher, the cylindrical protective tube 39 is effectively cooled, so that the exhaust gas temperature can be considerably lowered. This heating / cooling surge tube can prevent droplets of moisture and the like from entering the laminar flow meter 20 on the downstream side, and has an effect of cooling the high-temperature exhaust gas. The temperature setting indicator 31 measures the exhaust gas temperature and controls the sheathed heater coil 33 intermittently.

  Since the exhaust gas laminar flow meter 20 is used at an exhaust gas temperature of 100 ° C. or higher, it is necessary to pay more attention to the internal temperature distribution than in the case of a normal laminar flow meter used at room temperature. The pipeline is smoothly expanded from the heating / cooling surge tube 30 to the diameter of the laminar element 25 by the tapered tube 21, and a rectifying grid 23 is arranged upstream of the temperature / pressure measuring unit to prevent the influence of rectification and foreign matter. . The laminar element 25 has heat resistance, strength and shape stability, and can withstand exhaust gas and temperature changes. The detection end is arranged according to Japanese Patent Application No. 2002-212938 so that measurement of absolute pressure, differential pressure, and temperature necessary for flow rate calculation is important and the average area of the laminar element 25 can be detected. In particular, the area average value is important for the temperature, and a plurality of measurement ends of the thermocouple 24 are arranged in each area average value of at least four quadrants as a distribution of measurement points to detect the average temperature.

  The density of the exhaust gas slightly changes depending on the air-fuel ratio, but even in the theoretical mixing ratio, it is very close to air at about 1.0046 of the air density. For some fuels, the exhaust gas density can be determined from the value of the air / fuel ratio according to the fuel used, as a function of temperature and pressure alone. Viscosity changes with temperature in much the same way as air, and increases to about 1.8 times that at 0 ° C. at 300 ° C. Changes in density and viscosity coefficient are extremely important factors for laminar flowmeters, and calculation processing is performed to perform flow rate calculations based on these factors. The differential pressure is highly sensitive and responsive, and the selection of the pressure sensor is important. For the temperature measurement, the area average value of the four quadrants on the entrance side of the laminar element 25 is obtained. In this case, since it is considered that the response of the pressure measurement is about 10 ms, in this embodiment, the pressure sensor is connected to the absolute pressure sensor and the differential pressure sensor built in the flow rate calculation circuit 28 a little apart via the pressure conduits 26 and 27. The total exhaust gas flow rate is calculated every 10 ms by the flow rate calculation circuit 28 including the average temperature signal, and the flow rate signal 5 is output to the control system apparatus via the cable. This flow rate signal 5 becomes basic information of this apparatus. The remaining exhaust gas from the exhaust gas sample extraction is discharged through the discharge pipe 29 through the duct 13 having a portion opened to the atmospheric pressure.

  In this apparatus, the sample exhaust gas branch extraction amount is basically controlled by a proportional flow rate after being diluted with a constant and clean gas. The branch of the exhaust gas sample is suctioned to the oven 50 through the conduit 43 at a position 41 immediately after the exhaust laminar flow meter 20 and the exhaust gas flow rate is controlled at a constant 20 L / min or 25 L / min from the exhaust gas probe 42. The The conduit 43 includes a flexible conduit and a insulated conduit, but the temperature is maintained at approximately 70 ° C. or higher. The extracted exhaust gas sample stream 45 enters the temperature-controlled oven 50 from the conduit 43 via the connector 44, and is heat-exchanged in the pipe 46 inside thereof so as to be completely equal to the temperature of the oven 50. The pressure at the inlet 47 of the pipe 46 is used as the external pilot pressure of the pressure reducing valve 63 for dilution air. On the other hand, the clean dilution gas 60 is normally supplied at a pressure of 200 kPa or more and is used for exhaust gas dilution and sample bag purge. The exhaust gas dilution is conducted from the connector 61 of the oven 50 through the solenoid valve 62. In the oven 50, the pressure is reduced and the pressure is controlled by the pressure reducing valve 63, which is a pressure control valve with an external pilot, so as to be the same as the pipe line 46 in the oven of the exhaust sample flow. The inlet pressure of the electromagnetic valve 62 is monitored by a pressure gauge 64. The temperature of the dilution gas is made the same as the temperature of the oven 50 by using the pipe 65 to the dilution gas CFO or CFV 66 as a heat exchanger. The exhaust gas sample stream 45 is regulated at a constant flow rate by the CFO or CFV 48 by adjusting the inlet temperature to the oven temperature. The dilution gas is controlled to the same pressure as the exhaust side by the pressure reducing valve 63, which is a pressure control valve, and the temperature is set to the same temperature as the oven 50 via the heat exchange pipe 65, and is regulated to a constant flow rate by the dilution gas CFO or CFV 66. Is done. The CFO or CFV 48 and the dilution gas CFO or CFV 66 have the same temperature and pressure conditions on the inlet side, and further, the downstream side is joined by the flow path 49 so that the two gas flows are mixed to form a diluted exhaust gas flow 7. The outlet pressure of each CFO or CFV is monitored by a pressure gauge 67 to confirm the formation of a critical flow. The diluted exhaust gas flow 7 is sucked by a clean dry pump 68 having small pulsation, for example, so that the outlet pressure of the CFO or CFV 48, 66 can be made lower than the critical pressure, and pressurized and discharged to a gauge pressure of 20 kPa or more. 69. The flow rate of the diluted exhaust gas discharged from the dry pump 68 is the total flow rate of the CFO or CFV 48, 66, and the pressure is controlled by the relief valve 73 as a gauge pressure. When the dry pump 68 has a small pulsation such as a scroll type, the discharge side does not need pressure smoothing only by the relief valve control, and the exhaust gas laminar flow meter is operated by the variable cross-sectional area orifice type flow rate measurement control device 70. Based on the signal of the total exhaust gas flow rate 5 from 20, the flow is measured and controlled as a control diluted exhaust gas flow rate 6, and is sent as a bag sample sample gas to the sample bag mount 80 through the connector 81 and the sample tube 82. In the sample bag gantry 80, it is sent into each bag 86 from the distribution pipe 85 via the connector 83, the electromagnetic valve 84, and the like. The control diluted exhaust gas flow rate 6 is fed into the bag 86 set by the electromagnetic valve 84 for the measurement time, and is collected and accumulated. The sample gas of the bag is connected to the gas analyzer through the electromagnetic valve 58 through the solenoid valve 58 by switching the pipe line by the cooperation of the electromagnetic valves 84, 87, and 95, and the bag sample gas is sucked by the built-in pump of the analyzer and analyzed. To be served. The integrated value QI of the total exhaust gas flow rate and the integrated value qI of the control dilution exhaust gas flow rate (bag sampling flow rate) are extremely important as a measurement result together with the gas analysis value, and determine the performance of this apparatus. The internal temperature of the sample bag base 80 is controlled to a set temperature by a heater 91 with a temperature control device including a stirring fan, and is displayed by a temperature display 92. Before the measurement, the sample bag needs to be purged and leak-checked. The clean air used for dilution is diverted and received from the connector 93 of the sample bag mount 80, and the pressure is adjusted by the pressure reducing valve 94 and monitored by the pressure gauge 99. Furthermore, it is comprised so that it can send in to each bag sequentially via the electromagnetic valve 95. FIG. The bag filling pressure is monitored by a positive / negative coupled pressure gauge 96, including negative pressure, and the bag leak check is performed by checking the leak by making a negative pressure by relay transmission provided in the coupled pressure gauge 96, etc. A special alarm is issued. The purging of the bag is controlled by the sequencer 9 of the system control panel 90, and the electromagnetic valve 88, the discharge pump 98 and other related electromagnetic valves 58, 87, 84, etc. of each bag are automatically operated sequentially after a predetermined time. .

  The sample flow rate control delay circuit 8 for ensuring the synchronism between the engine operating condition change and the exhaust gas component change is generated for sampling at a constant flow rate τ1 that changes in accordance with the changing total exhaust gas flow rate. The calculation is performed separately for a certain delay time τ2, but τ1 obtained by dividing the volume V0 from the engine exhaust system to the exhaust laminar flow meter by the volume flow rate Q ｀ also affects the average temperature of the exhaust system. In general, assuming a mean temperature as a function of the temperature measured at the inlet of the flow meter, the volumetric flow rate Q can also be estimated. τ2 is about 0.4 to 0.5 sec in a numerical value determined from the use conditions of the measuring apparatus. The value of τ1 + τ2 is about 0.6 to 5.0 sec in normal mode operation, and becomes smaller during acceleration and high speed / high load operation, but becomes larger during deceleration. This delay time is calculated and output by the sample flow rate control delay circuit 8 of the system control panel 90 with a constant such as an exhaust system dead volume based on the exhaust gas flow signal 5 and the average exhaust gas temperature estimated value, and is output. It is a flow rate control signal of the flow rate measurement control device 70 and becomes a signal 10 that is also a measured flow rate signal.

    The variable cross-sectional area orifice type flow measurement control device 70 shown in FIG. 3 has a movable core 72 disposed in the orifice 71 and the linear actuator 74 determines the axial position of the movable core 72 according to the flow signal 5. The control dilution exhaust gas flow rate 6 from the outlet side pipe 76 is controlled by changing the orifice cross-sectional area 75 by changing the number of pulses of the internal pulse motor. In the flow rate measurement, an annular orifice cross-sectional area 75 is determined from the number of pulses, the diluted exhaust gas flow from the inlet-side pipe line 77 is sent to a control circuit 53 including a pressure sensor and a flow rate calculation through pressure conduits 78 and 79. The control dilution exhaust gas flow rate 6 from the outlet side pipe 76 is calculated based on the calibration with the temperature adjusted, and this is used as the basis of the integrated value QI. The displacement speed of the movable core 72 is set to 0.2 sec or less over the entire range, and can sufficiently follow the rapid change in the flow signal 5 of the exhaust gas. In addition, the pressure change at the orifice is basically negligible, and the differential pressure is about 10 kPa and can be used in a stable small differential pressure range. Further, the cross-sectional shape of the orifice cross-sectional area 75 is configured so as to be linearly proportional to the moving distance of the movable core 72. The control dilution exhaust gas flow rate 6 is obtained in the control circuit 53 including the actuator position signal pulse (cross-sectional area), the absolute pressure, the output of the differential pressure sensor, and the thermometer output based on the calibration. Thus, in the present apparatus, this is the most important result as the exhaust gas sample flow rate, and is displayed as an integrated value sent to the bag 86 by the sequencer 9 which is a sample integration circuit inside the system control panel 90. The outlet pressure of the dry pump 68 is controlled to a set pressure (gauge pressure) by the relief valve 73, and other than the control dilution exhaust gas flow rate 6 is discharged out of the system from the relief valve 73.

    The temperature of the oven 50 is controlled to a set temperature by a heater 51 with a stirrer and is displayed by a temperature display 52. The control dilution exhaust gas flow rate 6 is sent from the oven 50 to the sample bag frame 80 and enters one of the bags 86. At least four sets of bags are arranged on the sample bag pedestal 80, and there are electromagnetic valves, connectors, and the like so that they can be switched and used sequentially. Further, a discharge pump 98 for cleaning and exhausting each bag before measurement, a coupled pressure gauge 96 for checking a leak, and the like are provided. Normally, for cleaning, a dilution gas can be sent to each bag through a pressure reducing valve 94 at an appropriate pressure, and each solenoid valve is automatically controlled by a circuit 56 in the system control panel 90 as a sequencer. To be done. The system control panel 90 accommodates a system controller 55 including activation, safety, and display, a circuit 56 for bag operation, a sequencer 9 for integrating and displaying the sample flow rate, a sample flow rate control delay circuit 8, a monitor circuit 57, and the like. The overall system can be controlled centrally.

    In this exhaust proportional sampling device, the problem is that the change of the exhaust gas component is delayed from the change of the exhaust gas flow rate at the position where the diluted exhaust gas is diverted and the flow rate is controlled. The main delay time τ1 is the delay time to the position where the exhaust gas sample is separated from the engine exhaust system related to the exhaust gas flow rate. Furthermore, there is a time τ2 from the extraction of the exhaust gas sample inside the apparatus to the mixing and dilution with the dilution gas to divert and control the flow rate. τ1 is regarded as a value obtained by dividing the dead volume Vd by the total exhaust gas volume flow rate Qe (Te / T0). The dead volume of the engine exhaust system is determined by the engine specifications as a characteristic value of the engine, but the flow rate and the average exhaust gas temperature change. For the flow rate, the measured value of the exhaust gas flow meter is used as it is, the temperature is estimated very roughly, and the average value can be used by setting the inlet temperature of the exhaust gas flow meter and the assumed exhaust manifold temperature to 600 ° C., for example. Let's go. The exhaust gas temperature Te is boldly assumed to be the sum of the inlet temperature T1 and 1/2 (600 ° C.) of the total exhaust gas flowmeter being measured. That is, it can be calculated as τ1 = cl · (T0 / Te) · (1 / Qe). τ2 is a substantially constant time, and is often about 0.5 sec in this apparatus when the sample exhaust gas CFO or the CFV flow rate is 20 L / min. In FIG. 1, the flow rate control signal of the exhaust gas sample flow is configured to be controlled by τ thus calculated from the total exhaust gas flow rate measurement value.

It is a system diagram which shows the Example of the exhaust proportional sampling apparatus of this invention. It is a block diagram which shows the heating / cooling surge tube arrange | positioned in the measurement part and upstream of the laminar flowmeter used for the exhaust proportional sampling device of this invention. It is explanatory drawing which shows the structure of the variable cross-sectional area orifice type flow measurement control apparatus used for the exhaust proportional sampling apparatus of this invention.

Explanation of symbols

4 Total exhaust gas flow rate 5 Flow rate signal 6 Control dilution exhaust gas flow rate 7 Dilution exhaust gas flow 8 Sample flow rate control delay circuit 9 Sequencer 10 Signal 11 Automobile 12 Exhaust pipe 13 Duct 20 Exhaust laminar flow meter 21 Taper pipe 23 Rectifier grid 24 Thermocouple 25 Laminar element 26 Pressure conduit 27 Pressure conduit 28 Flow rate calculation circuit 29 Discharge tube 30 Heating / cooling surge tube 31 Temperature setting indicator 32 Pipe line 33 Sheathed heater coil 34 Temperature sensor 35 Rubber thin film tube with O-ring 36 Flange 37 Flange 38 Ventilation hole 39 Cylindrical protective tube 41 Immediately after 42 Exhaust gas probe 43 Conduit 44 Connector 45 Exhaust gas sample flow 46 Pipe line 47 Entrance 48 CFO or CFV
49 Flow path 50 Oven 51 Heater 52 Temperature indicator 53 Control circuit 55 System controller 56 Circuit 57 Monitor circuit 58 Solenoid valve 59 Connector 60 Diluting gas 61 Connector 62 Solenoid valve 63 Pressure reducing valve 64 Pressure gauge 65 Pipe line 66 Diluting gas CFO Or CFV
67 Pressure gauge 68 Dry pump 69 Pressure gauge 70 Variable cross-sectional area orifice type flow measurement control device 71 Orifice 72 Movable core 73 Relief valve 74 Linear actuator 75 Orifice cross-sectional area 76 Outlet side pipe line 77 Inlet side pipe line 78 Conduit 80 Sample Bag mount 81 Connector 82 Sample tube 83 Connector 84 Solenoid valve 85 Minute piping 86 Bag 87 Solenoid valve 88 Solenoid valve 89 Solenoid valve connector 90 System control panel 91 Heater 92 Temperature indicator 93 Connector 94 Pressure reducing valve 95 Solenoid valve 96 Compound pressure Total 98 Discharge pump 99 Pressure gauge

Claims (9)

  For one or more components contained in the internal combustion engine exhaust gas, an exhaust gas sample is extracted as a sample gas, diluted, and part of the flow rate controlled is bag-sampled to obtain the average gas concentration and amount of representative gas One of the proportional exhaust sampling devices to be obtained, it is arranged immediately after the exhaust pipe, and the exhaust gas total flow rate is set to a wide flow range using a laminar type flow meter that can accurately measure the flow rate of exhaust gas at 200 ° C or higher. In a sampling device that measures the exhaust gas sample flow rate that is always in a constant ratio with this flow rate value, measures it with appropriate responsiveness, and collects it in a bag while controlling it with a control valve with fast response Using CFO or CFV, a sample exhaust gas flow with a constant flow rate and clean dry air or nitrogen with a constant flow rate The flow rate is controlled using each CFO or CFV as a dilution gas, and suction, mixing, and pressurization are performed by a dry pump, a diluted exhaust gas sample having a constant pressure is adjusted, and a part thereof is proportional to the total exhaust gas flow rate. Control dilution exhaust gas sample is controlled in a variable flow area orifice type flow measurement control device in a wide flow range and fast response speed in a temperature atmosphere of 60 ° C or higher and collected in a bag maintained at an appropriate temperature, and this collection Controlled in proportion to the total exhaust gas flow rate value measured with a laminar flow meter, with the device configured so that the concentration and amount of the controlled diluted exhaust gas sample are proportional to the mass emission value of the component within its operating time The flow rate of the diluted exhaust gas is controlled and sampled in a bag, and an average exhaust gas sample is taken at a certain sampling time or the mileage of that time, and the sample is taken. And analysis of the sample, the total exhaust gas flow rate and sample flow rate value and the dilution exhaust sampling apparatus using a laminar type exhaust gas flowmeter and the like to obtain the mass emission values of the components of the engine exhaust gas ratio of.   2. A dilution gas exhaust sampling apparatus according to claim 1, wherein a variable cross-sectional area orifice type flow rate measurement control device is used as a device for measuring and controlling a part of the diluted exhaust gas sample flow to a flow rate proportional to the total exhaust gas flow rate. A diluted exhaust gas sampling apparatus that controls a diluted exhaust gas sample apparatus with a fast response speed of 0.3 seconds or less and a wide flow rate control range of 1:50 or higher even in the above high temperature atmosphere.   3. The dilution exhaust sampling apparatus according to claim 1 or 2, wherein when the engine exhaust gas flow rate and the component concentration change, the time change of the flow rate measurement value is ensured in order to ensure the synchronism between the exhaust gas flow rate change and the sampling time of the sample gas component. In relation to the delay of the gas component to the exhaust gas sample extraction branch point with respect to the exhaust gas sampling point (extraction branch point), the component concentration change of the gas sample due to the flow velocity and volume (dead volume) in the exhaust system For the time delayed from the exhaust time (flow rate change time) from the engine, a time lag that can be estimated from the exhaust system and dead volume to the exhaust gas sampling point and the average temperature and flow rate is obtained, and the exhaust generated inside the sampling device Control dilute exhaust gas after diluting and mixing from gas sample branch point A time lag correction circuit that can control the flow rate at the diversion point of the control diluted exhaust gas sample according to the change time of the exhaust gas component by providing a control circuit that can properly correct even a substantially constant time lag at Diluted exhaust sampling device.   In order to prevent condensation of low-boiling components such as moisture at the time of starting the engine and in a condition where the dew point of the diluted exhaust gas sample is higher than room temperature, the internal temperature of the exhaust gas flow meter is set to 100 ° C. A dilution exhaust sampling apparatus having a heating apparatus capable of maintaining the above, and further capable of maintaining the temperature of each part downstream from the dilution mixing section at 60 ° C. or higher and the bag holding temperature at 37 ° C. (corresponding to 6.2% moisture) or higher.   3. The diluted exhaust sampling system according to claim 1 or 2, wherein the pulsation of the flow in the exhaust pipe system in the low engine speed range prevents an unfavorable influence on the mixing of the front and rear changes of exhaust gas components and the flow rate measurement. In addition, in order to keep the delay and mixing of exhaust gas components at the same level as the actual vehicle, a surge tube with a small volume and a large pulsation damping effect is attached to the inlet side of the laminar flow meter immediately after the outlet of the engine exhaust pipe, A stainless steel heater is installed inside the surge tube to prevent condensation of low-boiling components at low temperatures such as when starting up when the exhaust gas temperature is below 200 ° C. Porous gold with a large surface area made of a material with good thermal conductivity that is effective for cooling the exhaust gas and silicone rubber film when the exhaust gas temperature is higher than 250 ° C. Using the plate, diluted exhaust sampling system the heating and cooling surge tube arranged upstream of the exhaust gas flowmeter.   A heating / cooling surge tube device through which the entire amount of exhaust gas of the internal combustion engine passes, an exhaust laminar flow meter for measuring the flow rate of the exhaust gas downstream of the heating / cooling surge tube device, and a position immediately after the exhaust laminar flow meter An exhaust gas probe that branches the exhaust gas sample flow, a CFO or CFV that regulates the exhaust gas sample flow to a constant flow rate, and another CFO that regulates dilution gas introduced from outside the system into the system at a constant flow rate. An oven apparatus for making the temperature and pressure conditions on the inlet side of each CFO or CFV of the exhaust gas sample stream and the dilution gas stream the same, and the exhaust gas sample stream and the dilution gas downstream of both the CFO or CFV Flow path to form a diluted exhaust gas stream, and the diluted exhaust gas stream from the exhaust laminar flow meter A variable cross-sectional area orifice type flow measurement control device for diverting a flow based on a gas gas flow meter signal to form a control diluted exhaust gas flow, and a bag capable of being filled with the control diluted exhaust gas flow. Diluted exhaust sampling device.   The flow rate of the exhaust gas of the internal combustion engine is measured with an exhaust laminar flow meter, the exhaust gas sample flow is branched at a position immediately after the exhaust laminar flow meter, and the exhaust gas sample flow is regulated to a constant flow rate by CFO or CFV, On the other hand, the dilution gas introduced from the outside into the system is regulated to a constant flow rate by another CFO or CFV, and the exhaust gas sample flow and the dilution gas flow have the same temperature and pressure conditions at the inlet side of each CFO or CFV. Alternatively, a combined exhaust gas stream is formed on the downstream side of the CFV to form a diluted exhaust gas flow, and the diluted exhaust gas flow is signaled from the exhaust laminar flow meter by the variable cross-sectional area orifice type flow measurement control device. To form a control dilution exhaust gas flow and set the control dilution exhaust gas flow as a bag sample sample gas for the measurement time Diluted exhaust sampling method characterized by subjecting to forced in the bag, which is controlled every time, taken out at the time of measurement analysis.   A pipe line that forms a gas flow path through which gas flows and has a vent hole formed in a pipe wall; and a temperature control device that is attached to the pipe line and that heats or cools the gas flow path to adjust the temperature; A surge tube member made of a rubber thin film that is arranged outside the pipeline so as to enclose the vent hole of the pipeline, and is hermetically arranged in the pipeline, and the surge tube member outside the surge tube member A heating / cooling surge tube device comprising: a cylindrical protective tube having rigidity and disposed in a state of enclosing the tube and having a plurality of vent holes formed in a tube wall.   The temperature control range is 100 ° C. to 200 ° C., the opening ratio of the cylindrical protective tube by the vent is 35% or more, or the temperature control device has a capacity of 700 W or more whose surface is made of stainless steel. The heating / cooling surge tube device according to claim 8, wherein a sheathed heater coil having an inner diameter is provided on an inner periphery of the pipe.

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