JP6195380B2 - Environmental test system - Google Patents

Description

  The present invention relates to an environmental test system for enabling a performance test of a vehicle engine under a low pressure such as a high altitude environment to be simulated.

  Engines (internal combustion engines) are installed in automobiles, construction / agricultural machinery, and other industrial machines, and have various performance requirements such as having predetermined performance and durability and meeting various standards such as exhaust gas regulations. Need to be satisfied. Therefore, various evaluation tests are performed on the engine.

  One of them is an evaluation test in an altitude environment (for example, at an altitude of 3000 m or 5000 m). As an engine characteristic under high altitude environment, not only engine output is reduced due to a decrease in engine intake pressure (decrease in air density), but exhaust gas purification performance is deteriorated and parts are damaged. The test (high altitude test) is indispensable.

Currently, in order to carry out the high altitude test, either the test vehicle is brought to the high altitude or a large high altitude environmental test chamber (low pressure chamber) built on the flat ground (low land) is used. There are many points.
(1) Problems when testing a test vehicle by bringing it to a high altitude ・ Expenses such as transportation of test equipment to the high altitude and labor costs are considerable.
・ Test items are limited to those that can be done at high altitude.
(2) Problems when building a high altitude environmental test room ・ It is difficult to secure installation space due to large equipment.
・ Very expensive to build.
-Since the high altitude environmental test room requires a high-strength building structure, it is difficult to add to the existing building.
(3) Problems when using the High Altitude Environmental Test Laboratory ・ Reservations are crowded and you are forced to wait for a long time.
・ Even if the need for additional tests arises, it is usually not possible to carry out immediately.
・ Rental use of the high altitude environmental test room requires a considerably high usage fee.

  The present invention has been made in consideration of the above-mentioned matters. The purpose of the present invention is not to carry the test object to the highland when performing the highland test, and it is not as large as a general highland environment test room. An object of the present invention is to provide an environmental test system that does not require equipment and can be implemented at low cost.

In order to achieve the above object, an environmental test system according to the present invention includes an intake system connected to an upstream side of an engine to be tested and an exhaust system connected to a downstream side. An environmental test system in which an upstream portion is open to the atmosphere, and the exhaust system is provided with a suction device that sucks air from the intake system, and bypasses the engine between the intake system and the exhaust system The opening of a pressure control valve connected to the bypass flow path and provided upstream of the portion where the bypass flow path is connected in the intake system can be adjusted, and the upstream end of the bypass flow path has the intake system Is connected to an intake buffer tank provided in the exhaust system, and a downstream end is connected to an exhaust buffer tank provided in the exhaust system or a downstream side of the exhaust buffer tank, and is more than the pressure control valve in the intake system. A primary air conditioner for adjusting the temperature of air sent to the engine is provided on the flow side, and a secondary air conditioner for adjusting the temperature of air sent to the engine is provided in the intake buffer tank. It is provided (Claim 1).

In the environmental test system, a flow meter for measuring a flow rate of air sent to the engine may be provided in the intake buffer tank .

The environmental test system according to the present invention includes an intake system connected to an upstream side of an engine to be tested and an exhaust system connected to a downstream side, and an upstream part of the intake system is open to the atmosphere. The exhaust system is an environmental test system provided with a suction device for sucking air from the intake system, and connects the intake system and the exhaust system with a bypass flow path that bypasses the engine, In the intake system, the opening degree of the pressure control valve provided upstream from the portion to which the bypass flow path is connected can be adjusted, and the upstream end of the bypass flow path is an intake buffer provided in the intake system Connected to the tank, the downstream end is connected to the exhaust buffer tank provided in the exhaust system or to the downstream side of the exhaust buffer tank, and the flow of air sent to the engine in the intake buffer tank Which is provided with a flow meter for measuring may be (claim 3).

  In the invention of the present application, it is not necessary to carry the test object to the highland when performing the highland test, and it is possible to carry out at a low cost without requiring a large facility such as a general highland environment test room. An environmental test system is obtained.

  That is, the environmental test system of the invention according to each claim of the present application is adapted to the test altitude by adjusting the opening degree of the pressure control valve while taking air into the intake system and the exhaust system by the suction device and flowing it. Air adjusted to pressure (pressure equivalent to high altitude environment) can be supplied to the test engine.

  In addition, since the environmental test system of the present invention is provided with a bypass flow path, even if the operating condition of the engine under test changes or when a transient operation is performed, the system (intake system and exhaust system) By keeping the flow rate constant at all times, pressure control and temperature control can be realized, and it is possible to prevent the exhaust system from becoming extremely low pressure and causing damage or the like.

In the environmental test system according to the first aspect of the present invention, air pulsation generated on the intake side and the exhaust side of the test engine can be buffered by the intake buffer tank and the exhaust buffer tank.

In the environmental test system according to the first aspect of the present invention, the temperature of the intake air that reaches the test engine by adjusting the temperature of the intake air whose temperature is adjusted in the primary air conditioner also in the secondary air conditioner closer to the test engine. It is possible to reduce the change and thus eliminate it.

In the environmental test system according to claims 2 and 3 , the flow meter is provided outside the intake buffer tank by providing a flow meter for measuring the flow rate of air sent to the engine under test in the intake buffer tank. Therefore, it is possible to obtain an ideal measurement environment that can minimize the influence of intrusion heat on the flowmeter while eliminating the need for an external pulsation buffer tank.

(A) And (B) is explanatory drawing which shows typically the basic principle and basic composition of the environmental test system which concern on one embodiment of this invention. It is explanatory drawing which shows schematically the whole structure of the said environmental test system. (A)-(C) is explanatory drawing which shows each schematically the modification of the bypass flow path in the said environmental test system. (A) is explanatory drawing which shows roughly the arrangement configuration of the dehumidification apparatus in the said environmental test system, (B) is explanatory drawing which shows schematically the arrangement configuration of a humidification line. (A) And (B) is explanatory drawing which shows roughly an example in the case of providing a secondary air conditioner in an intake buffer tank in the said environmental test system, and another example. (A) And (B) is explanatory drawing which shows the structure at the time of providing a flowmeter in and out of an intake buffer tank, respectively. It is explanatory drawing which shows the structure of the said intake buffer tank roughly. 3 is a flowchart schematically showing a configuration of a capacity control program in the environmental test system. It is a graph which shows an example of the uphill test pattern applicable to the said environmental test system.

  Embodiments of the present invention will be described below with reference to the drawings.

  As shown in FIGS. 1A and 2, the environmental test system according to the present embodiment (hereinafter referred to as the present system) is upstream of an engine 1 (hereinafter referred to as a test engine) 1 to be tested. And an exhaust system 3 connected to the downstream side. The upstream part of the intake system 2 is open to the atmosphere, and the exhaust system 3 is provided with a suction device 4 that sucks air from the intake system 2. Further, the intake system 2 and the exhaust system 3 are connected by a bypass flow path 5 that bypasses the engine 1 under test, and pressure control provided upstream of the portion of the intake system 2 to which the bypass flow path 5 is connected. The opening degree of the valve 6 can be adjusted.

  Then, the present system adjusts the opening of the pressure control valve 6 while taking the air into the intake system 2 and the exhaust system 3 by the suction device 4 to flow, thereby adjusting the pressure according to the test altitude (equal to the high altitude environment). The air adjusted to the pressure of the test engine 1 can be supplied to the test engine 1. That is, if the opening degree of the pressure control valve 6 is decreased while the suction device 4 is operated at a constant speed, the pressure on the downstream side of the pressure control valve 6 is decreased, and the opening degree of the pressure control valve 6 is adjusted (throttle control). ), The pressure of the air supplied to the test engine 1 can be adjusted to a predetermined value (set value). The opening degree of the pressure control valve 6 can be adjusted, for example, by a control unit (not shown) that receives a signal indicating pressure from a pressure gauge 7 (see FIG. 2) provided in the intake system 2.

  Further, in this system, the air flowing from the intake system 2 to the exhaust system 3 branches and flows into the engine flow path 8 and the bypass flow path 5 passing through the test engine 1, and the flow rate ratio is determined by the test engine 1. Dominated by driving conditions. More specifically, when the test engine 1 is stopped, the entire amount of air flowing from the intake system 2 to the exhaust system 3 flows through the bypass flow path 5, and after the test engine 1 is started, suction according to the engine speed is performed. An amount of air flows through the engine flow path 8, and the flow rate of the air flowing through the bypass flow path 5 decreases accordingly. Therefore, in the present system, the bypass flow path 5 is provided, so that even if the operating state of the engine 1 is changed or transient operation is performed, the system (in the intake system 2 and the exhaust system 3) By keeping the flow rate constant at all times, pressure control and temperature control can be realized, and it is also possible to prevent the exhaust system 3 from becoming extremely low pressure and causing damage or the like.

  Here, the suction device 4 is a suction blower, for example, for ensuring the flow rate of the air flowing through the intake system 2 and the exhaust system 3, and at a constant speed operation, slightly reduces the exhaust amount of the engine 1 under test. The amount of suction (flow rate) with an allowance (for example, a remaining capacity of about 25%) is maintained, thereby realizing an energy saving operation. The suction amount is set by an external setting device, for example. Moreover, as a blower used for the suction device 4, a positive displacement blower (for example, a Roots blower) having a small flow rate fluctuation with respect to a pressure fluctuation is preferable.

  The above is the basic principle of the present system. Next, the basic configuration of the present system incorporating this basic principle will be described with reference to FIG. 1B and FIG.

  First, in the engine test, a test at a standard atmospheric pressure is also required in order to compare a flatland environment and a highland environment. Therefore, in this system, in order to be able to adjust the pressure of the air supplied to the test engine 1 so as to support not only the high altitude environment but also the standard atmospheric pressure environment, as shown in FIG. A booster blower 9 is provided upstream of the intake system 2. As a result, even if the air introduced into the intake system 2 is lower than the standard atmospheric pressure, the pressure is increased by the booster blower 9 so that the influence of the low pressure during the test or at the sea level (elevation) of the installation location of the system. Is cancelled, and air at standard atmospheric pressure can be supplied to the test engine 1.

  Further, since air pulsation occurs on the intake side and exhaust side of the test engine 1, an intake buffer tank 10 is provided at a position downstream of the pressure control valve 6 in the intake system 2 for buffering the pulsation. The exhaust buffer tank 11 is provided at a position upstream of the suction device 4 in the exhaust system 3. In the case of a transient test in which the number of revolutions of the test engine 1 is rapidly changed, intake pressure fluctuations occur with an instantaneous flow rate change due to the inertia of the intake air flow. Therefore, when carrying out such a test, it is necessary to sufficiently increase the volume of the intake buffer tank 10 and the exhaust buffer tank 11 to enhance the buffer effect.

  Furthermore, after the test engine 1 is started, the volume of air sent to the suction device 4 expands as the temperature of the engine exhaust gas increases, and pressure control becomes impossible when the processing capacity of the suction device 4 is exceeded. Therefore, in order to avoid such a situation, in the present system, the upstream side of the suction device 4 (the downstream side of the connection portion of the downstream end of the bypass flow path 5 in the exhaust system 3 and the upstream side of the suction device 4). The exhaust gas cooler (exhaust gas heat exchanger) 12 for adjusting the conditions on the suction side of the suction device 4 is provided at the position). By providing the exhaust gas cooler 12, the suction device 4 can be protected from the high-temperature exhaust gas, and the exhaust gas introduced into the suction device 4 is cooled to some extent, thereby exhausting the upstream side of the suction device 4. Even if the operating condition of the test engine 1 changes due to transient operation or the like, the stable control can be performed.

  Here, since the flow rate of the air sucked into the suction device 4 is affected by the temperature at the inlet of the suction device 4 (blower suction temperature), the temperature at the outlet of the exhaust gas cooler 12 is required to make this flow rate constant. Must always be constant. However, in the actual test, the load of the exhaust gas cooler 12 is completely different when the test engine 1 is started (during idling) and during rated operation, and as the test progresses (between the start and end of the test) In some cases, the suction temperature cannot be made constant. For example, the temperature becomes lower at the start of the test. Therefore, in this system, a slight correction operation is performed by a control system (control unit) (not shown) that performs capacity correction (temperature correction) of the suction device 4 in accordance with the blower suction temperature. In FIG. 4, a substantially constant flow rate can be obtained.

  In the example shown in FIG. 1 (B), the upstream end of the bypass flow path 5 is connected to the intake buffer tank 10, and the downstream end is connected to the downstream side of the exhaust buffer tank 11. It doesn't flow back to the side easily. In addition, since the mechanical backflow cannot be prevented only with this connection arrangement, a micro differential pressure gauge (an example of a differential pressure sensor) 13 is attached between the intake buffer tank 10 and the exhaust buffer tank 11 to monitor the backflow. Alarm notification and automatic stop of the test are performed.

  However, the present invention is not limited to this, and the configuration of the bypass flow path 5 can be variously changed. For example, as shown in FIG. 3A, if the downstream end of the bypass passage 5 is connected to the exhaust buffer tank 11 and a check valve 14 is provided in the bypass passage 5, mechanical backflow prevention is achieved. The differential pressure gauge 13 is not necessary. However, in this case, since the valve resistance of the check valve 14 is manifested as a differential pressure between the intake side pressure and the exhaust side pressure, the pressure of the air sent to the test engine 1 is slightly different from the pressure in the actual high altitude environment. There is a risk that it will be different. In this respect, in the example shown in FIG. 1B, the valve resistance of the check valve 14 is eliminated, so that a state that is relatively close to the actual highland environment can be obtained, and it can be said that it is excellent.

  Moreover, the structure of the bypass flow path 5 shown to FIG. 1 (B) can also be changed as shown to FIG. 3 (B) and (C). Here, in the example shown in FIG. 3B, a hopper-shaped guide 15 is arranged in the exhaust buffer tank 11 to which the downstream end of the bypass flow path 5 is connected. In the example shown in FIG. 3C, an integrated buffer tank 16 in which an intake buffer tank 10 and an exhaust buffer tank 11 are integrated is provided, and the intake buffer tank 10 and the exhaust buffer tank 11 in the integrated buffer tank 16 are provided. A counter pressure monitor 13 is attached to perform back flow monitoring. However, in terms of suppressing the influence of radiant heat on the exhaust side, as shown in FIGS. 1 (B), 3 (A), and (B) rather than adopting the integrated buffer tank 16 shown in FIG. 3 (C). It is preferable to separate the intake buffer tank 10 and the exhaust buffer tank 11 from each other. The configuration of the partition plate 16a for partitioning the intake buffer tank 10 and the exhaust buffer tank 11 in the integrated buffer tank 16 shown in FIG. 3C and the through holes 16b provided in the partition plate 16a can be changed as appropriate. .

  In this system, as shown in FIG. 1 (B), the temperature of the intake air temperature adjusting device (the air sent to the engine 1 under test) is adjusted to the upstream portion of the intake system 2 (upstream side of the pressure control valve 6). An example of a primary air conditioner 17) is installed, and as a temperature control process, air (intake air) sucked into the intake system 2 from outside air is cooled, dehumidified and heated by the intake air temperature control device 17 Then, the temperature of the intake air is set to a target value (required intake air temperature), and then supplied to the test engine 1. As shown in FIG. 2, the intake air temperature adjusting device 17 includes a heater 17a and a cooler 17b.

  Here, all the air flowing into the intake air temperature control device 17 must be introduced into the outside air. In particular, when performing a low temperature test in which the temperature of the intake air is a negative temperature range, It is preferable to prevent the moisture in the intake air from icing and clogging in the cooling unit, and to enable continuous operation without frost. For this reason, in this system, as shown in FIG. 4A, a dehumidifying device 18 is provided upstream of the intake air temperature adjusting device 17 (in this example, upstream of the booster blower 9), as required. A configuration is adopted in which the intake air introduced into the device 17 is dehumidified in advance by the dehumidifier 18 to obtain a low dew point.

  In the example shown in FIG. 4A, as described above, the intake air is dehumidified by the intake air temperature adjusting device 17 in the upstream portion of the intake system 2 in the present system. After this dehumidification, the intake air is used as the test engine 1. When the humidity control (humidification) of the intake air is performed before the air is supplied, the humidity is preferably controlled on the downstream side of the pressure control valve 6 because the humidity is affected by the atmospheric pressure fluctuation. In performing this humidity control, for example, as shown in FIG. 4B, a humidification line 19 is provided in the intake buffer tank 10 with a downstream portion inserted and connected, and a steam boiler disposed upstream of the humidification line 19 is provided. The steam generated at 20 is ejected into the intake buffer tank 10 from a humidifying nozzle 21 provided at the downstream portion of the humidifying line 19, and the amount of ejection is midstream of the humidifying line 19 (between the steam boiler 20 and the humidifying nozzle 21). It can be considered that the humidity is controlled by the humidity control valve 22 provided in the above.

  In order to allow the intake air whose temperature has been adjusted in the intake air temperature control device 17 to reach the test engine 1 without changing its temperature, it must be connected as short as possible and sufficiently insulated. However, no matter how much heat insulation is provided, in addition to the heat intrusion from the wall surface of the pipe (the pipe connected to the engine 1) constituting the intake system 2, the metal material itself constituting the pipe and the intake buffer tank 10 The influence of the stored heat cannot be avoided, and the heat effect on the intake air becomes more prominent as the difference between the ambient temperature and the intake air temperature increases. Further, even when the intake air flow rate of the test engine 1 is extremely small (such as when idling), it is affected by the intrusion heat and the retained heat, and particularly near the intake port of the test engine 1 and the outlet of the intake buffer tank 10. There is a possibility that the intake air of (test engine 1 contact point) is at a temperature completely different from the control temperature by the intake air temperature control device 17.

  Therefore, in this system, as a solution, as shown in FIG. 5 (A), a secondary air conditioner for adjusting the temperature of the intake air sent to the test engine 1 corresponding to the intrusion heat and the retained heat. By arranging 23 in the intake buffer tank 10, it is possible to reduce the temperature change of the intake air and to eliminate it. The secondary air conditioner 23 may have the same configuration as that of the intake air temperature control device 17, and the temperature control of the secondary air conditioner 23 is performed by, for example, the temperature of the downstream portion in the intake buffer tank 10. This can be performed by a control unit (not shown) that receives a signal indicating the temperature from the temperature sensor 24 (see FIG. 2).

  If the distance from the intake buffer tank 10 to the intake port of the test engine 1 cannot be shortened, as shown in FIG. 5B, the intake buffer tank 10 to the test engine 1 in the engine flow path 8 is used. You may provide the return flow path 25 branched from the site | part between them and connected with the upstream of the secondary air conditioner 23. FIG. In this case, by circulating the temperature-adjusted air through the engine flow path 8 and the return flow path 25, the temperature change until the intake air is sent from the intake buffer tank 10 to the test engine 1 can be suppressed. Increases as the upstream end of the return flow path 25 approaches the suction port of the test engine 1 in the engine flow path 8.

  When measuring the intake air flow rate in the engine test, as shown in FIG. 6A, if the flow meter 26 and the pulsation buffer buffer tank 27 are attached immediately before the intake port of the engine 1 under test, the flow meter 26 and the pulsation buffer are used. The buffer tank 27 undergoes a temperature change due to heat intrusion from the outside. For example, when the intake air amount of the test engine 1 is small, the tendency increases. Even if the temperature of the flow rate is corrected in such a situation, an error occurs and it is considered that the correct flow rate cannot be measured.

  Therefore, in this system, as shown in FIG. 6 (B), a flow meter 26 for measuring the flow rate of the air sent to the test engine 1 can be attached in the intake buffer tank 10 so as to pulsate. It is possible to obtain an ideal measurement environment that can minimize the influence of intrusion heat on the flow meter 26 while eliminating the need for the external buffer tank 27. In this example, as shown in FIG. 7, a flow meter 26 is provided in a cylindrical flow path 10d that penetrates a partition wall 10c that divides the inside of the intake buffer tank 10 into an upstream portion 10a and a downstream portion 10b. The channel 10d is the only channel that directly communicates the upstream portion 10a and the downstream portion 10b. Moreover, in this example, as shown in FIG. 7, the pressure gauge 7, the fine differential pressure gauge 13, the secondary air conditioner 23, and the temperature sensor 24 are provided with respect to the downstream part 10b.

  When the equipment capacity of this system is configured with equipment selected based on the maximum capacity of the engine under test 1 that is scheduled to be tested and the maximum load test conditions, the equipment capacity is compared to the actual test. Tend to be excessive. In particular, in the suction device 4, even if the operation is performed with an installation capacity larger than necessary, most of the intake air flows through the bypass flow path 5 and the operation is performed without any problem, but the energy consumption is always the maximum value. This results in lack of energy saving.

  As a solution to this problem, the present system can execute the capacity control program shown in FIG. This capacity control program is for automatically calculating the required capacity when the three test conditions are input, and controlling the suction device 4 so as to operate at the optimum capacity. That is, as shown in FIG. 8, when the shaft output of the test engine 1 is input as the first test condition (step S1), the capacity control program calculates the engine heat value based on the internal combustion engine heat account. The fuel consumption is calculated based on the fuel heat generation amount (step S3), and the intake air amount is calculated from the theoretical air-fuel ratio (step S4). On the other hand, when the test altitude and the test temperature are input as the second and third test conditions (step S5), the air density is calculated (step S6). Based on the intake air amount obtained in step S4 and the air density obtained in step S6, the required flow rate (blower flow rate) of the suction device 4 is calculated (step S7), and the suction device 4 (blower) is operated. A load factor is set (step S8). Therefore, if this capacity control program is executed, not only the suction device 4 but also the intake air temperature control device 17, the exhaust gas cooler 12, and the like can be drastically saved.

  The system can be applied to, for example, a climbing test. That is, it is possible to simulate a climbing environment by setting a test altitude and a climbing time based on a pre-planned climbing test pattern as shown in FIG. 9 and reflecting this setting in the control of the pressure control valve 6. It is.

  As described above, this system controls the pressure, temperature and humidity on the intake side of the engine 1 under test and the pressure on the exhaust side, enabling pressure control according to the test altitude. It can also be said that this is a simple high altitude environment test system that creates a high altitude environment only in the pipes on the intake side and exhaust side of the test engine 1 that are closely related to atmospheric pressure fluctuations. Therefore, if this system is used, large-scale equipment having a pressure-proof structure test room such as a general high-altitude environment test room is not required, so that space-saving and energy-saving operation and low-cost equipment introduction are possible. Is possible.

  Further, in the present system, as shown in FIG. 2, the suction device 4, the exhaust buffer tank 11 and the exhaust gas cooler 12 are unitized as one blower unit 28, and the pressure control valve 6 and the intake buffer tank 10 are one. The unit is configured as one pressure adjusting unit 29, and the intake air temperature control device 17 and the dehumidifying device 18 are also unitized. Therefore, the installation location, such as an existing bench, is not limited. Even if you want to move to a new location, it can be relocated with relatively simple construction. However, it goes without saying that which part is unitized in this system can be changed each time according to the equipment scale and the like.

  In addition, this invention is not limited to said embodiment at all, Of course, it can change and implement variously in the range which does not deviate from the summary of this invention.

DESCRIPTION OF SYMBOLS 1 Engine 2 Intake system 3 Exhaust system 4 Suction device 5 Bypass flow path 6 Pressure control valve 7 Pressure gauge 8 Engine flow path 9 Booster blower 10 Intake buffer tank 10a Upstream part 10b Downstream part 10c Partition wall 10d Cylindrical flow path 11 Exhaust buffer Tank 12 Exhaust gas cooler 13 Differential pressure gauge 14 Check valve 15 Guide 16 Integrated buffer tank 17 Intake air temperature controller 17a Heater 17b Cooler 18 Dehumidifier 19 Humidification line 20 Steam boiler 21 Humidification nozzle 22 Humidity control valve 23 Two Next air conditioner 24 Temperature sensor 25 Return flow path 26 Flow meter 27 Pulsation buffer buffer tank 28 Blower unit 29 Pressure adjustment unit

Claims (3)

An intake system connected to the upstream side of the engine to be tested and an exhaust system connected to the downstream side, the upstream part of the intake system is open to the atmosphere, and the exhaust system from the intake system An environmental test system provided with a suction device for sucking in air,
The intake system and the exhaust system are connected by a bypass flow path that bypasses the engine, and the opening degree of the pressure control valve provided upstream of the portion to which the bypass flow path is connected in the intake system is adjusted. possible and then,
An upstream end of the bypass flow path is connected to an intake buffer tank provided in the intake system, and a downstream end is connected to an exhaust buffer tank provided in the exhaust system or a downstream side of the exhaust buffer tank,
A primary air conditioner for adjusting the temperature of the air sent to the engine is provided upstream of the pressure control valve in the intake system, and the temperature of the air sent to the engine in the intake buffer tank An environmental test system, characterized in that a secondary air conditioner for adjusting the air conditioner is provided . The environmental test system according to claim 1 , wherein a flow meter for measuring a flow rate of air sent to the engine is provided in the intake buffer tank . An intake system connected to the upstream side of the engine to be tested and an exhaust system connected to the downstream side, the upstream part of the intake system is open to the atmosphere, and the exhaust system from the intake system An environmental test system provided with a suction device for sucking in air,
The intake system and the exhaust system are connected by a bypass flow path that bypasses the engine, and the opening degree of the pressure control valve provided upstream of the portion to which the bypass flow path is connected in the intake system is adjusted. Made possible
An upstream end of the bypass flow path is connected to an intake buffer tank provided in the intake system, and a downstream end is connected to an exhaust buffer tank provided in the exhaust system or a downstream side of the exhaust buffer tank,
An environmental test system , wherein a flow meter for measuring a flow rate of air sent to the engine is provided in the intake buffer tank .