Engine test air supply system and pressure, temperature and humidity adjusting method

Abstract

The invention discloses an engine test air supply system which comprises an air inlet, the air inlet is connected with a temperature regulation and control unit through a pipeline, the temperature regulation and control unit is connected with a humidity regulation and control unit through a pipeline, the humidity regulation and control unit is connected with a normal-pressure fan through a pipeline, and the output end of the normal-pressure fan is connected with a pressure stabilizing section through a pipeline. The output end of the pressure stabilizing section is connected with an air outlet through a pipeline, the air outlet is connected with a booster fan through a pipeline, and the booster fan is connected with the pressure stabilizing tank through a pipeline. Meanwhile, the invention further discloses a method for adjusting the temperature, the humidity and the pressure through the air supply system, the humidity and the temperature of the air are adjusted before pressurization so that out-of-control of the temperature and the humidity caused in the pressurization process can be compensated, and air entering the engine under different altitude conditions can be simulated more accurately; parameters obtained during engine testing are more fit with parameters during actual operation of the engine, and a data basis is provided for adjustment of the engine.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of automobile engines, and relates to an engine test air supply system with multi-stage fan supercharging and PID decoupling regulation, and also relates to a pressure, temperature and humidity regulation method using the system. BACKGROUND

[0002] In a high-altitude or low-pressure environment (such as an area above 396.9 m in Xi'an), the local atmospheric pressure is usually 4-6 kPa lower than the standard atmospheric pressure (101.325 kPa), which leads to insufficient intake of diesel engines, directly affecting the combustion efficiency and emission performance. According to the regulations such as ISO 1585 and GB / T 21404-2021, engine test data must be corrected based on standard atmospheric conditions, otherwise it will lead to power calibration deviation (typical error ≥5%) and emission data distortion, which seriously affects the test reliability.

[0003] The traditional solution uses a single centrifugal fan or a mechanical supercharger to compensate for the pressure of the intake air, but there are the following problems: large pressure fluctuation (±2 kPa), which cannot meet the stringent requirements of pressure stability (target: ±0.5 kPa) for steady-state operating tests (such as ESC cycle); temperature and humidity are out of control: the air compression process is accompanied by significant temperature rise (ΔT≈8~15℃) and humidity drop (ΔRH≈20%), while the engine test standard (such as ISO 8178) requires temperature and humidity to be controlled within ±1℃ / ±3%RH, otherwise it will affect the accuracy of air-fuel ratio calculation; low energy efficiency: the efficiency of single-stage supercharging drops by more than 30% at high pressure ratio (>1.05), resulting in a sharp increase in energy consumption.

[0004] Due to the strong coupling relationship between pressure, temperature and humidity (such as: supercharging leading to temperature rise → humidity sensor reading drift), the existing PID single-loop control strategy cannot achieve coordinated regulation, often showing: overshoot oscillation: temperature regulation causes humidity fluctuation, and pressure regulation causes temperature fluctuation; response lag: humidity compensation is delayed by 10-15 seconds due to thermal inertia, which cannot meet the dynamic test requirements.

[0005] In view of the above problems, a multi-stage adaptive supercharging system is urgently needed, which can ensure accurate pressure compensation while achieving rapid and stable temperature and humidity through decoupling control algorithm, to meet the dual requirements of compliance and test data traceability. SUMMARY

[0006] The engine test air supply system of the application has the characteristics of accurately simulating the pressure of air in different regions.

[0007] The technical scheme adopted by the present application is an engine test air supply system, comprising an air inlet, the air inlet is connected with a temperature control unit through a pipeline, the temperature control unit is connected with a humidity control unit through a pipeline, the humidity control unit is connected with a normal pressure fan through a pipeline, the output end of the normal pressure fan is connected with a pressure stabilizing section through a pipeline, the output end of the pressure stabilizing section is connected with an air outlet through a pipeline, the air outlet is connected with a booster fan through a pipeline, and the booster fan is connected with a pressure stabilizing tank through a pipeline.

[0008] The present application is characterized in that: The air outlet and the pressure stabilizing tank are respectively connected with the air inlet through branch pipes, a return air electric regulating valve is fixedly connected on the pipeline connecting the air outlet with the air inlet, and a pressure relief valve is fixedly connected on the pipeline connecting the pressure stabilizing tank with the air inlet.

[0009] The temperature control unit comprises a preheating device connected with the air inlet, the preheating device is connected with a first surface cooler through a pipeline, the first surface cooler is connected with a heating device through a pipeline, the heating device is connected with the humidity control unit through a pipeline, and the humidity control unit controls the steam amount participating in humidity adjustment through a steam valve.

[0010] A second surface cooler is connected between the normal pressure fan and the pressure stabilizing section through a pipeline.

[0011] The output end of the pressure stabilizing tank, the air inlet and the output end of the humidity control unit are all fixedly connected with a temperature and humidity sensor, and an absolute pressure sensor is fixedly connected in the pressure stabilizing tank.

[0012] An initial efficiency filtering section is fixedly connected between the air inlet and the preheating device, a high efficiency filtering section is fixedly connected between the pressure stabilizing section and the air outlet, and differential pressure switches are arranged in the initial efficiency filtering section and the high efficiency filtering section respectively.

[0013] Another object of the present application is to provide a pressure control method of the test air supply system, which is specifically performed according to the following steps: Step 1: connecting the air inlet of the engine to be tested with the output end of the pressure stabilizing tank and maintaining idling operation, at this time, setting a test target pressure and setting initial operating frequencies of the normal pressure fan and the booster fan; Step 2: closing the pressure relief valve on the pressure stabilizing tank, then switching the engine to rated power operation, at this time, the booster fan increases in frequency, the frequency of the normal pressure fan remains unchanged, and the pressure in the pressure stabilizing tank reaches the target pressure ±1kpa; Step 3: in subsequent tests, when the engine power is between idling and rated power, adjusting the opening degree of the pressure relief valve to make the pressure in the pressure stabilizing tank be the target pressure ±0.5kpa.

[0014] Another object of the present application is to provide a temperature control method of the test air supply system, which is specifically performed according to the following steps: Step 1: Preset the target temperature. When the temperature and humidity sensor at the air inlet detects that the air temperature entering the system is greater than 30℃, adjust the opening of the inlet valve of the first surface cooler as follows:

[0015] Where A1 is K, the opening degree of the inlet valve of the first surface cooler, T1 is the input air temperature, and K is a coefficient ranging from 0.01 to 0.035. When the inlet air temperature is less than or equal to 30℃, the inlet valve of the surface cooler is closed. Step 2: The second surface cooler (14) uses the temperature detected by the temperature and humidity sensor at the output end of the humidity control unit as the base temperature and uses PID to control the opening of the water inlet valve of the second surface cooler.

[0016] Another objective of this application is to provide a temperature control method for the experimental gas supply system, which is specifically carried out according to the following steps: Step 1: Preset the target humidity, and then obtain the actual humidity of the gas entering the engine through the temperature and humidity sensor at the output end of the pressure tank; Step 2: When the actual humidity is less than the target humidity, the opening of the steam valve of the humidity control unit is adjusted by PID control. When the actual humidity is greater than or equal to the target humidity, the steam valve is closed.

[0017] The beneficial effects of this invention are: The engine test air supply system provided in this application regulates the temperature and humidity of the air before adjusting the air pressure through a surface cooler and a humidity control unit to compensate for temperature and humidity runaway caused during the pressurization process, and more accurately simulates the air entering the engine under different altitude conditions. Simultaneously, this application also uses a preheating device to compensate for changes in intake air temperature caused by changes in the external environment, making the parameters obtained during engine testing more closely match the parameters during actual engine operation, providing a data basis for engine adjustments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the engine test air supply system of the present invention.

[0019] In the diagram: 1. Air inlet; 2. Temperature control unit; 3. Humidity control unit; 4. Normal pressure fan; 5. Pressure stabilizing section; 6. Air outlet; 7. Booster fan; 8. Pressure stabilizing tank; 9. Return air electric regulating valve; 10. Pressure relief valve; 11. Preheating device; 12. First surface cooler; 13. Heating device; 14. Second surface cooler; 15. Temperature and humidity sensor; 16. Absolute pressure sensor; 17. High-efficiency filter section; 18. Primary filter section; 19. Differential pressure switch. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0021] Example 1: like Figure 1 As shown, the engine test air supply system includes an air inlet 1, which is connected to a temperature control unit 2 via a pipe. The temperature control unit 2 is connected to a humidity control unit 3 via a pipe. The humidity control unit 3 is connected to a normal pressure fan 4 via a pipe. The output end of the normal pressure fan 4 is connected to a pressure stabilizing section 5 via a pipe. The output end of the pressure stabilizing section 5 is connected to an air outlet 6 via a pipe. The air outlet 6 is connected to a booster fan 7 via a pipe. The booster fan 7 is connected to a pressure stabilizing tank 8 via a pipe.

[0022] When testing the engine, the pressure stabilizing tank 8 is connected to the engine air intake. Outside air enters the system through the air intake 1. The temperature, humidity and pressure of the air are adjusted by the temperature control unit 2, humidity control unit 3 and booster fan 7 respectively, and then sent into the pressure stabilizing tank 8 for storage, providing a stable gas source for engine testing.

[0023] Example 2: Based on Example 1: like Figure 1 As shown, the air outlet 6 and the pressure tank 8 are respectively connected to the air inlet 1 through branch pipes. A return air electric regulating valve 9 is fixedly connected to the pipe connecting the air outlet 6 and the air inlet 1, and a pressure relief valve 10 is fixedly connected to the pipe connecting the pressure tank 8 and the air inlet 1.

[0024] After the booster fan 7 adjusts the air pressure, it sends the air into the pressure stabilizing tank 8 for storage. However, the required air intake varies depending on the engine's operating power. If the engine's air intake for a period of time is less than the air supplied by the booster fan 7 in the same amount of time, the pressurized air will accumulate in the pressure stabilizing tank 8, potentially causing the air pressure to rise and exceed the preset pressure. In this case, the pressure can be reduced by adjusting the opening of the pressure relief valve 10 to return some air to the air inlet 1. If the pressure in the pressure stabilizing tank 8 still rises even when the pressure relief valve 10 is fully open, the opening of the return air electric regulating valve 9 can be adjusted to return some air to the air inlet 1, reducing the air intake of the booster fan 7 and maintaining the pressure in the pressure stabilizing tank 8.

[0025] like Figure 1 As shown, the temperature control unit 2 includes a preheating device 11 connected to the air inlet 1. The preheating device 11 is connected to the first surface cooler 12 through a pipe. The first surface cooler 12 is connected to the heating device 13 through a pipe. The heating device 13 is connected to the humidity control unit 3 through a pipe. The humidity control unit 3 controls the amount of steam involved in humidity regulation through a steam valve.

[0026] like Figure 1 As shown, the atmospheric pressure fan 4 and the pressure stabilizing section 5 are connected by a second surface cooler 14 through a pipeline.

[0027] In the temperature control unit 2, the first surface cooler 12 is used for preliminary cooling to keep the air temperature below 10-13°C. When the test is conducted in winter and the outside temperature is too low, the preheating device 11 can be activated to preheat the air that is about to enter the first surface cooler 12 to avoid the temperature being too low and difficult to adjust.

[0028] The power of the preheating device 11 and the heating device 13 are 18kW and 28kW, respectively.

[0029] After the first surface cooler 12 adjusts the air temperature, the humidity changes with the temperature. At this time, the heating device 13 increases the air temperature to compensate for the increase in humidity caused by the decrease in temperature.

[0030] like Figure 1 As shown, temperature and humidity sensors 15 are fixedly connected to the output end of the pressure stabilizing tank 8, the air inlet 1, and the output end of the humidity control unit 3. An absolute pressure sensor 16 is fixedly connected inside the pressure stabilizing tank 8.

[0031] The absolute pressure sensor 16 and various temperature and humidity sensors 15 acquire the temperature, humidity and pressure information of the air after different processing nodes, providing a data basis for subsequent adjustments within the system.

[0032] Example 3: Based on Example 1: like Figure 1 As shown, a primary filter section 18 is fixedly connected between the air inlet 1 and the preheating device 11, and a high-efficiency filter section 17 is fixedly connected between the pressure stabilizing section 5 and the air outlet 6. Differential pressure switches 19 are respectively installed in the primary filter section 18 and the high-efficiency filter section 17.

[0033] The high-efficiency filter section 17 and the pre-filter section 18 filter particulate impurities from the outside air, preventing damage to the engine turbocharger caused by particulate impurities entering it.

[0034] Example 4: The specific method for pressure regulation using the engine test air supply system provided in this application is as follows: Step 1: Connect the engine's air intake to the output of the pressure stabilizing tank 8, and then keep the engine at idle speed. At this time, set the pressure to be measured, and set the initial operating frequency of the atmospheric pressure fan 4 and the booster fan 7. The initial frequency of the atmospheric pressure fan 4 is set to 15Hz, and the initial frequency of the booster fan 7 is set to 10Hz. Step 2: Turn the engine to rated power, keep the return air electric regulating valve 9 and the pressure relief valve 10 closed, and continuously increase the operating frequency of the booster fan 7 while keeping the operating frequency of the atmospheric pressure fan 4 unchanged until the pressure in the pressure tank 8 reaches the target pressure ±1 kPa. Then stop keeping the operating frequency of the booster fan 7 unchanged. Step 3: Change the engine operating power for testing. During the test, adjust the opening of the pressure relief valve 10 to make the pressure inside the pressure stabilizing tank 8 the target pressure ±0.5 kPa.

[0035] Example 5: The specific method for temperature regulation using the engine test air supply system provided in this application is as follows: Step 1: Preset the target temperature. When the temperature and humidity sensor 15 at air inlet 1 detects that the air temperature is greater than 30℃, adjust the opening of the water inlet valve of the first surface cooler 12. The adjustment method is as follows:

[0036] Where A1 is K, the opening degree of the inlet valve of the first surface cooler 12, T1 is the input air temperature, and K is a coefficient ranging from 0.01 to 0.035. When the inlet air temperature is less than or equal to 30℃, the inlet valve of the surface cooler is closed. Step 2: Using the temperature at the output of the humidity control unit 3 as the base temperature, the opening of the water inlet valve of the second surface cooler 14 is controlled by PID control.

[0037] In this formula, K p T is the proportional gain coefficient; i is the integral action time; b is the proportional action weight; w is the real-time temperature value; x is the target temperature setpoint; T is the time taken for one PID cycle.

[0038] In step 1, when the air temperature at the air inlet 1 is less than 8°C, the preheating device is activated to preheat the device that will enter the first surface cooler 12.

[0039] Example 6: The specific method for humidity regulation using the engine test air supply system provided in this application is as follows: Step 1: Preset the target humidity, and then obtain the actual humidity of the gas entering the engine through the temperature and humidity sensor 15 at the output end of the pressure tank 8; Step 2: After the first surface cooler 12 cools the air by opening the valve, the heating device 13 is started; Step 3: When the actual humidity is less than the target humidity, the opening of the steam valve in humidity control unit 3 is adjusted by PID control. When the actual humidity is greater than or equal to the target humidity, the steam valve is closed. The specific formula is as follows:

[0040] In this formula, K p T is the proportional gain coefficient; iis the integral action time; b is the proportional action weight; w is the real-time humidity value; x is the target humidity setpoint; T is the time taken for one PID cycle.

[0041] How to use: The procedure for testing the engine using the system provided in this application is as follows: Preset phase: First, connect the engine's air intake to the output of the pressure stabilizing tank 8, then start the engine and keep it at idle speed. At this time, preset the target temperature, humidity and pressure to be measured, and set the initial frequency of the normal pressure fan 4 and the booster fan 7.

[0042] Then, the engine is switched to rated power, while the return air electric regulating valve 9 and the pressure relief valve 10 are kept closed. The operating frequency of the booster fan 7 is continuously increased until the pressure in the pressure tank 8 reaches the target pressure ±1 kPa. After that, the operating frequency of the booster fan 7 is kept constant.

[0043] Gas supply phase: Outside air enters the system through the air inlet 1. First, the temperature and humidity sensor 15 detects the air temperature. When the air temperature is greater than 30°C, the cooling effect is adjusted by regulating the opening and closing of the water inlet valve of the first surface cooler 12. When the air temperature is between 8°C and 30°C, the water inlet valve of the first surface cooler 12 is closed. When the air temperature is below 8°C, the preheating device 11 is started. After the preheating device 11 preheats the air, the cooling effect of the first surface cooler 12 is adjusted by regulating the opening and closing of the water inlet valve of the first surface cooler 12.

[0044] After air passes through the first surface cooler 11, the operation of the heating device 13 is controlled according to the operating status of the first surface cooler 11. If the water inlet valve of the first surface cooler 11 has been opened or closed, the heating device 13 is started for heating; otherwise, the heating device is not started. After the air is processed by the heating device, it enters the humidity control unit 3. At this time, the humidity control unit 3 obtains the actual humidity information of the gas entering the engine through the temperature and humidity sensor 15 at the output end of the pressure tank 8 and compares it with the target humidity. When the actual humidity is less than the target humidity, the opening of the steam valve of the humidity control unit 3 is adjusted through PID control. When the actual humidity is greater than or equal to the target humidity, the steam valve is closed. During the initial operation, the steam valve remains closed.

[0045] After passing through the humidity control unit 3, the air is sent into the second surface cooler 14. The second surface cooler 14 obtains the actual temperature information through the temperature and humidity sensor 15 at the output end of the humidity control unit 3, and then calculates the opening of the water inlet valve through PID control to adjust the air to the target temperature.

[0046] After passing through the second surface cooler 14, the air is pressurized by the booster fan 7 and sent into the pressure stabilizing tank 8. The pressure inside the tank is monitored in real time by the absolute pressure sensor 16. When the pressure inside the pressure stabilizing tank 8 is too high or too low, the opening of the pressure relief valve 10 is adjusted to control the return of some gas to the air inlet to maintain the pressure balance inside the pressure stabilizing tank 8, so as to provide stable gas that meets the test standards for engine testing.

Claims

1. An engine test air supply system, characterized in that, It includes an air inlet (1), which is connected to a temperature control unit (2) via a pipe. The temperature control unit (2) is connected to a humidity control unit (3) via a pipe. The humidity control unit (3) is connected to a normal pressure fan (4) via a pipe. The output end of the normal pressure fan (4) is connected to a pressure stabilizing section (5) via a pipe. The output end of the pressure stabilizing section (5) is connected to an air outlet (6) via a pipe. The air outlet (6) is connected to a booster fan (7) via a pipe. The booster fan (7) is connected to a pressure stabilizing tank (8) via a pipe.

2. The engine test air supply system according to claim 1, characterized in that, The air outlet (6) and the pressure tank (8) are respectively connected to the air inlet (1) through branch pipes. A return air electric regulating valve (9) is fixedly connected to the pipe connecting the air outlet (6) and the air inlet (1). A pressure relief valve (10) is fixedly connected to the pipe connecting the pressure tank (8) and the air inlet (1).

3. The engine test air supply system according to claim 2, characterized in that, The temperature control unit (2) includes a preheating device (11) connected to the air inlet (1). The preheating device (11) is connected to the first surface cooler (12) through a pipe. The first surface cooler (12) is connected to the heating device (13) through a pipe. The heating device (13) is connected to the humidity control unit (3) through a pipe. The humidity control unit (3) controls the amount of steam involved in humidity regulation through a steam valve.

4. The engine test air supply system according to claim 3, characterized in that, The atmospheric pressure fan (4) and the pressure stabilizing section (5) are connected by a second surface cooler (14) through a pipeline.

5. The engine test air supply system according to claim 5, characterized in that, Temperature and humidity sensors (15) are fixedly connected to the output end of the pressure stabilizing tank (8), the air inlet (1), and the output end of the humidity control unit (3). An absolute pressure sensor (16) is fixedly connected inside the pressure stabilizing tank (8).

6. The engine test air supply system according to claim 1, characterized in that, A primary filter section (18) is fixedly connected between the air inlet (1) and the preheating device (11), and a high-efficiency filter section (17) is fixedly connected between the pressure stabilizing section (5) and the air outlet (6). The primary filter section (18) and the high-efficiency filter section (17) are respectively equipped with differential pressure switches (19).

7. A pressure control method for an experimental gas supply system, characterized in that, The pressure control of the engine test air supply system according to claim 5 is performed according to the following steps: Step 1: Connect the air inlet of the engine under test to the output end of the pressure stabilizing tank (8) and maintain idle speed. At this time, set the target pressure for testing and set the initial operating frequency of the atmospheric pressure fan (4) and the booster fan (7). Step 2: Close the pressure relief valve on the pressure stabilizing tank (8), and then turn the engine to rated power. At this time, the booster fan (7) increases the frequency, while the normal pressure fan (4) remains unchanged until the pressure inside the pressure stabilizing tank (8) reaches the target pressure ±1 kPa. Step 3: During subsequent tests, when the engine power is between idle speed and rated power, adjust the opening of the pressure relief valve (10) to make the pressure inside the pressure stabilizing tank (8) the target pressure ±0.5 kPa.

8. A temperature control method for an experimental gas supply system, characterized in that, The temperature control, using the engine test air supply system of claim 5, is performed according to the following steps: Step 1: Preset the target temperature. When the temperature and humidity sensor (15) of the air inlet (1) detects that the air temperature is greater than 30°C, adjust the opening of the water inlet valve of the first surface cooler (12). The adjustment method is as follows: Where A1 is K is the opening degree of the inlet valve of the first surface cooler (12), T1 is the input air temperature, K is a coefficient of 0.01 to 0.035, and the inlet valve of the first surface cooler (12) is closed when the inlet temperature is less than or equal to 30℃. Step 2: The second surface cooler (14) uses the temperature at the output of the humidity control unit (3) as the base temperature and uses PID control to control the opening of the water inlet valve of the second surface cooler (14).

9. The engine test air supply system according to claim 1, characterized in that, When adjusting the temperature in step 1, if the outside temperature is below 8°C, the preheating device (11) is activated to raise the air temperature, and then the first surface cooler (12) is used for adjustment. After passing through the first surface cooler (12), the air temperature is maintained at 10°C to 13°C.

10. A humidity control method for an experimental gas supply system, characterized in that, The humidity control, using the engine test air supply system of claim 5, is performed according to the following steps: Step 1: Preset the target humidity, and then obtain the actual humidity of the gas entering the engine through the temperature and humidity sensor (15) at the output end of the pressure tank (8); Step 2: When the actual humidity is less than the target humidity, adjust the opening of the steam valve of the humidity control unit (3) by PID control. When the actual humidity is greater than or equal to the target humidity, close the steam valve.

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