Device and method for measuring injection rule and injection quantity of high-flow dimethyl ether injector

Abstract

The invention provides a device and method for measuring the injection rule and the injection amount of a high-flow dimethyl ether injector, and belongs to the technical field of fuel injection testing. The device comprises a constant volume chamber assembly, a pipeline valve assembly, a pressure container assembly and a control assembly; the constant volume chamber assembly comprises a constant volume chamber main body, a tested dimethyl ether ejector, a second pressure sensor and a nitrogen purging interface; the pressure vessel assembly includes: a pressure vessel body; the pipeline valve assembly comprises a first liquid return pipe, and a first proportional pressure valve, a fourth pressure sensor, a throttling valve, a mass flow meter, a second proportional pressure valve, a filter, a pressure regulating pipe and a first liquid return valve are sequentially mounted on the first liquid return pipe; a pressure reducing ejector is mounted on the pressure regulating pipe; the control assembly comprises a controller and a data acquisition card. The measuring device and method are suitable for the dimethyl ether fuel, and a theoretical basis is provided for practical application of the dimethyl ether fuel in a compression ignition type internal combustion engine.

Description

Technical Field

[0001] The invention belongs to the technical field of fuel injection testing, and in particular relates to a device and method for measuring the injection law and injection amount of a large-flow dimethyl ether injector. Background Art

[0002] In the field of compression-ignition engines, the combustion chamber is the core unit of energy release, carrying out key functions such as fuel-air mixing, compression ignition, and energy conversion. As a test device that simulates the working environment of the combustion chamber, the constant-volume chamber can establish pressure and temperature conditions similar to the actual operating conditions of the combustion chamber through valve control, fuel injection, and pressure regulation. This is used to obtain basic data such as fuel injection patterns and injection quantities, providing technical support for combustion chamber design optimization and performance matching.

[0003] When dimethyl ether is used as a new fuel in compression-ignition engines, its injection rate, injection pattern, and other parameters must be clearly defined to verify its compatibility with the combustion chamber's requirements. Testing in a constant-volume chamber avoids the high costs (such as engine modifications and operating condition adaptation and debugging) and high risks (such as engine failures caused by fuel mismatch and test safety hazards) associated with direct testing on an engine bench. This is an effective technical approach for early-stage fuel characterization research.

[0004] Chinese patent CN109386420A discloses a method for measuring multiple injection patterns of diesel fuel, and its idea of ​​using a constant volume chamber to conduct fuel injection testing is of reference value. However, due to the differences between dimethyl ether and diesel fuel in terms of physical and chemical properties (such as volatility, viscosity, and cetane number performance), compression ignition compatibility, and the pressure control structure design and control logic (such as pressure regulation accuracy and dynamic response characteristics) of the constant volume chamber of this patent are developed based on diesel fuel testing requirements, they cannot meet the requirements of dimethyl ether for the test environment (such as pressure stability and pressure regulation range), and are difficult to be directly used for accurate testing of dimethyl ether injection characteristics. Therefore, it is necessary to develop a device and method for measuring the injection pattern and injection amount of a large-flow dimethyl ether injector. Summary of the Invention

[0005] In order to overcome the deficiencies in the prior art, the present invention proposes an injection law and injection quantity measuring device for a large-flow dimethyl ether injector.

[0006] In order to achieve the above object, the present invention proposes the following technical solutions:

[0007] A device for measuring the injection pattern and injection amount of a large-flow dimethyl ether injector includes a constant volume chamber component, a pipeline valve component, a pressure vessel component, and a control component; wherein the constant volume chamber component includes:

[0008] Main body of the constant volume chamber;

[0009] The dimethyl ether injector under test is installed in the main body of the constant volume chamber;

[0010] The second pressure sensor and the third pressure sensor are installed on the constant volume chamber body;

[0011] The nitrogen purge interface is opened on the side wall of the constant volume chamber;

[0012] Pressure vessel components include:

[0013] Pressure vessel body;

[0014] Exhaust valve, installed on the pressure vessel body, used to discharge nitrogen;

[0015] The gas phase return port is installed on the pressure vessel body and is used to discharge dimethyl ether vapor.

[0016] Pipeline valve components include:

[0017] A first liquid return pipe, one end of which is fixedly connected to and communicates with the constant volume chamber body, and the other end of which is fixedly connected to and communicates with the pressure vessel body; a first proportional pressure valve, a fourth pressure sensor, a throttle valve, a mass flow meter, a second proportional pressure valve, a filter, and a first liquid return valve are sequentially installed on the first liquid return pipe in the direction of dimethyl ether flow in the first liquid return pipe;

[0018] A pressure regulating pipe is installed on the first liquid return pipe and is in communication with the first liquid return pipe; its two ends are connected to both sides of the first proportional pressure valve, and a pressure reducing ejector is installed on the pressure regulating pipe;

[0019] The control component includes a controller and a data acquisition card.

[0020] Furthermore, a second liquid return pipe is connected between the constant volume chamber body (10) and the pressure vessel body (1), one end of which is fixedly connected to and communicated with the constant volume chamber body (10), and the other end of which is fixedly connected to and communicated with the pressure vessel body (1); a safety valve (15) and a second liquid return valve (6) are installed on the second liquid return pipe.

[0021] During the test, if the back pressure fails, the pressure in the constant volume chamber body will increase, and the safety valve will automatically open to release the pressure, avoiding safety risks caused by excessive pressure.

[0022] Furthermore, a cooling water circulation water path is provided inside the wall panel of the constant volume chamber body (10), and a cooling water inlet (25) and a cooling water return port (28) are provided on the wall panel of the constant volume chamber body (10); the cooling water inlet (25) is externally connected to cooling water below 20° C., and a cooling water return check valve (26) and a cooling water reflux switch (27) are installed on the pipeline of the cooling water return port (28).

[0023] Furthermore, a heat exchanger (18) is installed on the first liquid return pipe, and cooling water with a temperature not higher than 20°C is passed into the heat exchanger (18) to ensure that the temperature of the dimethyl ether flowing through the mass flow meter (22) is stable and does not exceed 30°C.

[0024] Furthermore, the bottom surface of the cavity of the constant volume chamber body (10) is a conical bottom surface.

[0025] Furthermore, a method for measuring the injection pattern and injection amount of a large-flow dimethyl ether injector comprises the following steps:

[0026] S1: nitrogen purge;

[0027] S2: injection back pressure is established;

[0028] Among them, S2 specifically includes the following steps:

[0029] S2.1: Under the control of the controller (31), the first liquid return valve (5), the second liquid return valve (6) and the exhaust valve (7) are opened, the first proportional pressure valve (16) and the pressure reducing ejector (17) are fully opened, the pressure of the second proportional pressure valve (23) is set to 0.5 MPa, and the gas phase return port (9) is closed; at this time, which is time t0, the third pressure sensor (13) monitors the pressure in the constant volume chamber body (10), and sets the pressure in the constant volume chamber body (10) at this time to P0;

[0030] S2.2: At time t0, the nitrogen pressure in the constant volume chamber body (10) is P0, the dimethyl ether injector (11) to be tested is fully opened, and high-pressure dimethyl ether is sprayed into the constant volume chamber body (10). As the dimethyl ether is injected, the pressure monitored by the third pressure sensor (13) rises to P1 at time t1. Since the pressure difference before and after the second proportional pressure valve (23) is greater than 0.5 MPa, the second proportional pressure valve (23) automatically opens, and nitrogen and liquid dimethyl ether flow into the pressure vessel body (1), and nitrogen begins to be discharged from the exhaust valve (7); the dimethyl ether injector (11 to be tested) remains fully opened. Since the second proportional pressure valve (23) is open, the pressure in the constant volume chamber body (10) monitored by the third pressure sensor (13) remains P1 until reaching t2;

[0031] S2.3: Starting from time t2, the tested dimethyl ether injector (11) continuously performs N injections at the maximum injection amount. After each of the aforementioned N-1 injections, the controller (31) adjusts the pressure of the second proportional pressure valve (23) so that the pressure monitored by the third pressure sensor (13) approaches the set value P2. After multiple adjustments, after the Nth injection, the controller does not change the pressure of the second proportional pressure valve (23), and the pressure monitored by the third pressure sensor (13) stabilizes at P2. This is time t3, at which the minimum back pressure is established. Continue to perform M injections at the maximum injection amount. After each injection, if the pressure monitored by the third pressure sensor (13) stabilizes at P2 without changing the pressure of the second proportional pressure valve (23), it indicates that the exhaust is completed. This is time t4.

[0032] S2.4: Under the control of the controller (31), the first proportional pressure valve (16) and the pressure reducing injector (17) are closed; the tested dimethyl ether injector (11) performs a single injection according to the maximum injection amount. After the injection is completed, the pressure of the first proportional pressure valve (16) is adjusted and the pressure reducing injector (17) is opened to reduce the pressure to P3, where P3>P2; this is repeated S times, and the pressure is reduced to P3 each time while changing the first proportional pressure valve (16) and the pressure reducing injector (17), indicating that the injection back pressure is established; this is time t5;

[0033] S3: Get the injection pattern;

[0034] S4: Measure the injection amount.

[0035] Furthermore, step S1 includes the following steps:

[0036] S1.1: Under the control of the controller (31), the dimethyl ether injector (11), the second proportional pressure valve (23), the exhaust valve (7), the gas phase return port (9), and the second liquid return valve (6) are all closed, the first proportional pressure valve (16) and the pressure reducing injector (17) are fully opened, and the first liquid return valve (5) is opened;

[0037] S1.2: After the operator connects the nitrogen purge interface (29) to 0.8 MPa nitrogen, the gas phase return port (9) is opened, and the second proportional pressure valve (23) is fully opened; the dimethyl ether residual liquid in the constant volume chamber body (10) is blown into the pressure vessel body (1) by the nitrogen, and at the same time, the dimethyl ether vapor and nitrogen in the pressure vessel body (1) are discharged from the gas phase return port (9);

[0038] S1.3: When the controller (31) detects that the value of the fourth pressure sensor (20) is stable, the controller (31) first closes the gas phase return port (9), then opens the exhaust valve (7), and finally closes the first liquid return valve (5); the nitrogen purge process is now complete.

[0039] Furthermore, step S3 includes the following steps:

[0040] S3.1: The compression ignition engine cam generates a "6+1" tooth signal, with a multi-tooth signal between teeth 1 and 2. This multi-tooth signal is separated from tooth 1 by 15° CA. CA stands for cam angle.

[0041] S3.2: The falling edge of tooth 1 sends a "pressure regulating signal" to the controller (31). After receiving the pressure regulating signal, the controller (31) controls the pressure of the first proportional pressure valve (16) to be increased to 5 MPa to prevent the first proportional pressure valve (16) from opening after dimethyl ether is sprayed from the constant volume chamber body (10). At the same time, the controller (31) sends a "collection signal" to the data acquisition card (30), and the data acquisition card (30) collects the data monitored by the second pressure sensor (12).

[0042] S3.3: The falling edge of the multi-tooth sends an "injection signal" to the controller (31). After receiving the injection signal, the controller (31) controls the tested dimethyl ether injector (11) to inject dimethyl ether in any amount. The injection pulse width must end before the falling edge of the tooth 4 signal, that is, the maximum injection pulse width is 165°CA;

[0043] S3.4: The falling edge of tooth 4 sends an "integration signal" to the controller (31). After receiving the integration signal, the controller (31) monitors the data of the third pressure sensor (13) and the set pressure of the first proportional pressure valve (16), and simultaneously controls the mass flow meter (22) to perform flow integration and stop collecting data from the second pressure sensor (12); the data acquisition card (30) transmits the collected data from the second pressure sensor (12) to the industrial control computer (32), and the industrial control computer (32) performs low-pass filtering and differential integration on the data to obtain a waveform of the injection regularity.

[0044] Furthermore, step S4 includes: after the falling edge of tooth 4 is triggered, the controller (31) first adjusts the control pressure of the first proportional pressure valve (16) to 3MPa to relieve pressure and accumulate the dimethyl ether injection amount. Before the falling edge of tooth 6 arrives, multiple injections are performed through the pressure reducing injector (17) to reduce the pressure data of the third pressure sensor (13) to P3; during this process, the mass flow meter (22) monitors the flow rate, and the total discharge amount during the pressure reduction process is the injection amount of this time. The falling edge of tooth 6 sends a "stop signal" to the controller (31). After receiving the stop signal, the controller (31) controls the mass flow meter (22) to stop accumulating, and the injection amount measurement ends.

[0045] The above technical solutions can achieve the following beneficial effects:

[0046] 1. This solution, specifically for dimethyl ether (DME), employs a different design for injection backpressure. Not only does it adjust the pressure of the second proportional pressure valve 23 to bring the pressure in the pressure vessel body closer to the set value P2, but after multiple adjustments, the pressure monitored by the third pressure sensor 13 stabilizes at P2 after the Nth injection (step S2.3). Subsequently, with the first proportional pressure valve 16 and pressure-reducing injector 17 closed, the pressure is reduced to P3 by adjusting these valves again. After these two adjustments, injection backpressure is established.

[0047] 2. The knowledge of injection pattern and injection amount is related to the rotation of the compression ignition engine cam. The falling edge of the cam tooth generates a trigger signal, which enables the controller or data acquisition card to collect data or stop collecting data, thereby realizing automatic data processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is the overall diagram of the device;

[0049] Figure 2 This is the data diagram of the third pressure sensor during the injection back pressure establishment process;

[0050] Figure 3 It is a signal diagram of injection pattern and injection quantity controlled by cam.

[0051] 1. Pressure vessel body; 2. Liquid level sensor; 3. First temperature sensor; 4. First pressure sensor; 5. First liquid return valve; 6. Second liquid return valve; 7. Exhaust valve; 8. Liquid phase filling port; 9. Gas phase return port; 10. Constant volume chamber body; 11. Tested dimethyl ether injector; 12. Second pressure sensor; 13. Third pressure sensor; 14. Second temperature sensor; 15. Safety valve; 16. First proportional pressure valve; 17. Pressure reducing injector; 18. Heat exchanger; 19. Third temperature sensor; 20. Fourth pressure sensor; 21. Throttle valve; 22. Mass flow meter; 23. Second proportional pressure valve; 24. Filter; 25. Cooling water inlet; 26. Cooling water return check valve; 27. Cooling water reflux switch; 28. Cooling water return port; 29. ​​Nitrogen purge interface; 30. Data acquisition card; 31. Controller; 32. Industrial computer. DETAILED DESCRIPTION

[0052] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0053] Example 1: Figure 1 As shown, a device for measuring the injection law and injection amount of a large-flow dimethyl ether injector includes a constant volume chamber component, a pipeline valve component, a pressure vessel component and a control component.

[0054] Among them, the constant volume chamber assembly includes the following structure:

[0055] The chamber body 10 is made of 304 stainless steel and has an internal cavity with a capacity of 6.5L and a pressure resistance of 25MPa. The bottom of the chamber body 10 adopts a 5° conical design, with the bottom of the cavity lower in the middle and higher around the edges. Based on this design, it can eliminate bubbles contained in the chamber body 10. The top of the chamber is equipped with a dimethyl ether injector 11 to inject liquid dimethyl ether into the cavity of the chamber body 10.

[0056] The second pressure sensor 12, the third pressure sensor 13, and the second temperature sensor 14 are all installed on the constant volume chamber body 10, among which the second temperature sensor 14 is used to monitor the injection temperature of the dimethyl ether injector 11 under test, the second pressure sensor 12 is used to reflect the injection law of the dimethyl ether injector 11 under test, and the third pressure sensor 13 is used to display the pressure of the constant volume chamber body 10.

[0057] The nitrogen purge interface 29 is opened on the side wall of the constant volume chamber body 10 and is connected to the 0.8MPa nitrogen source through a pipeline and a valve. By opening the valve on the corresponding pipeline, nitrogen is blown into the cavity of the constant volume chamber body 10 from the nitrogen purge interface 29 to purge the residual fuel.

[0058] The cooling water circulation waterway is opened inside the wall panel of the constant volume chamber body 10, and a cooling water inlet 25 and a cooling water return port 28 are respectively opened on the wall panel of the constant volume chamber body 10. Among them, the cooling water inlet 25 is externally connected to cooling water below 20°C, and a cooling water return check valve 26 and a cooling water reflux switch 27 are installed on the pipeline of the cooling water return port 28. Based on the one-way check principle of the cooling water return check valve 26, the cooling water in the pipeline of the cooling water return port 28 is prevented from flowing back. Under the action of the circulating cooling water, it is ensured that the temperature in the constant volume chamber body 10 is not higher than 30°C. By turning on and off the cooling water reflux switch 27, the circulation of the cooling water can be stopped or not. When the device is not tested, the cooling water reflux switch 27 is used to close the water circulation waterway.

[0059] The pressure vessel assembly then includes the following construction:

[0060] Pressure vessel 1, for storing dimethyl ether, has a capacity of 120 L, a rated pressure of 0.5 MPa, and a maximum pressure of 1.6 MPa. A pressurizing line connects pressure vessel 1 to a dimethyl ether injector 11 under test. This line is equipped with a pressurizing assembly for pressurizing the dimethyl ether in pressure vessel 1 and directing it to the injector 11 under test.

[0061] The liquid level sensor 2, the first temperature sensor 3, and the first pressure sensor 4 are all installed in the pressure vessel body 1. The first temperature sensor 3 is used to monitor the temperature in the pressure vessel body 1. The first pressure sensor 4 is used to monitor the pressure in the pressure vessel body 1. The liquid level sensor 2 is used to monitor the dimethyl ether residual amount in the pressure vessel body 1.

[0062] Liquid filling port 8 is provided in pressure vessel body 1. Since dimethyl ether is easily vaporized, it will be discharged from pressure vessel body 1 through exhaust valve 7 or gas return port 9 during the test process. Therefore, when liquid level sensor 2 detects that the liquid level in pressure vessel body 1 is below the low level threshold, liquid dimethyl ether can be added to pressure vessel body 1 through liquid filling port 8 at a certain pressure, such as 1.2 MPa.

[0063] The exhaust valve 7 is installed on the pressure vessel body 1 and is used to discharge nitrogen.

[0064] The gas phase return port 9 is provided in the pressure vessel body 1 and is used for discharging gas from the pressure vessel body 1. The discharged gas contains dimethyl ether vapor and therefore needs to be reprocessed.

[0065] Then, the pipeline valve assembly includes the following structures:

[0066] The first liquid return pipe has one end fixedly connected to and in communication with the tapered surface of the constant volume chamber body 10, and the other end fixedly connected to and in communication with the pressure vessel body 1. Liquid dimethyl ether can flow from the first liquid return pipe into the pressure vessel body 1. To ensure that the dimethyl ether in the constant volume chamber body 10 remains liquid, the pressure in the constant volume chamber body 10 is maintained above 1 MPa. Attached to the first liquid return pipe, along the direction of dimethyl ether flow, are, in order, a first proportional pressure valve 16, a heat exchanger 18, a third temperature sensor 19, a fourth pressure sensor 20, a throttle valve 21, a mass flowmeter 22, a second proportional pressure valve 23, a filter 24, and the first liquid return valve 5. The filter is used to filter impurities from the dimethyl ether. Cooling water at a temperature no higher than 20°C is passed through the heat exchanger 18 to ensure that the temperature of the dimethyl ether flowing through the mass flowmeter 22 is stable and does not exceed 30°C. This ensures that the pressure in the pressure vessel body 1 is maintained at approximately 0.5 MPa, improving the accuracy of injection volume measurement and reducing safety risks associated with the measurement device. The third temperature sensor 19 is used to monitor the temperature of the dimethyl ether flowing through the mass flow meter 22 .

[0067] The pressure regulating pipe is installed on the first liquid return pipe and communicated with the first liquid return pipe; its two ends are connected to the two sides of the first proportional pressure valve 16, and a pressure reducing ejector 17 is installed on the pressure regulating pipe.

[0068] The second liquid return pipe has one end fixedly connected to and in communication with the conical surface of the constant volume chamber body 10, and the other end fixedly connected to and in communication with the pressure vessel body 1. A safety valve 15 and a second liquid return valve 6 are installed on the second liquid return pipe. If back pressure regulation fails and the pressure in the constant volume chamber body 10 rises and exceeds the threshold set by the safety valve 15, the safety valve 15 automatically opens to release the pressure, ensuring the internal pressure of the chamber body 10 is safe.

[0069] Finally, the control components include:

[0070] The controller 31 is electrically connected to the liquid level sensor 2, the first temperature sensor 3, the first pressure sensor 4, the third pressure sensor 13, the second temperature sensor 14, the third temperature sensor 19, the fourth pressure sensor 20, the mass flow meter 22 and the filter 24, and is used to monitor the data of the above components.

[0071] The data acquisition card 30, model NIPCIe-6361, is used to collect data from the second pressure sensor 12. At the same time, the data acquisition card 30 is electrically connected to the controller 31, and the controller 31 sends a "collection signal" to the data acquisition card 30.

[0072] The industrial computer 32 exchanges data with the controller 31 via a CAN bus and with the data acquisition card 30 via the PCIe bus. It controls the entire test device and receives corresponding measurement results. The entire device, except for the controller 31, data acquisition card 30, and industrial computer 32, is housed within an explosion-proof enclosure. The liquid level sensor 2, all temperature sensors, and all pressure sensors are intrinsically safe.

[0073] Example 2: A method for measuring the injection pattern and injection amount of a large-flow dimethyl ether injector, comprising the following steps:

[0074] S1: Nitrogen purge.

[0075] S1 specifically includes the following steps:

[0076] S1.1: Under the control of the controller, the tested dimethyl ether injector 11, the second proportional pressure valve 23, the exhaust valve 7, the gas phase return port 9, and the second liquid return valve 6 are all closed, the first proportional pressure valve 16 and the pressure reducing injector 17 are fully opened, and the first liquid return valve 5 is opened;

[0077] S1.2: After the operator connects the nitrogen purge port 29 to 0.8 MPa nitrogen, the gas phase return port 9 is opened, and the second proportional pressure valve 23 is fully opened. The dimethyl ether residual liquid in the constant volume chamber body 10 is blown into the pressure vessel body 1 by the nitrogen. At the same time, the dimethyl ether vapor and nitrogen in the pressure vessel body 1 are discharged from the gas phase return port 9.

[0078] S1.3: When the controller detects that the value of the fourth pressure sensor 20 is stable, the controller first closes the gas phase return port 9, then opens the exhaust valve 7, and finally closes the first liquid return valve 5. The nitrogen purge process is now complete.

[0079] S2: Injection back pressure is established (see Figure 2 ).

[0080] S2 specifically includes the following steps:

[0081] S2.1: Under the control of the controller, the first liquid return valve 5, the second liquid return valve 6, and the exhaust valve 7 are opened, the first proportional pressure valve 16 and the pressure reducing ejector 17 are fully opened, the pressure of the second proportional pressure valve 23 is set to 0.5 MPa, and the gas phase return port 9 is closed. At this time, t0, the third pressure sensor 13 monitors the pressure in the constant volume chamber body 10 and sets the pressure in the constant volume chamber body 10 at this time to P0.

[0082] S2.2: At time t0, the nitrogen pressure in the constant volume chamber main body 10 is P0 (about 0.8 MPa); the tested dimethyl ether injector 11 is fully open, and high-pressure dimethyl ether is sprayed into the constant volume chamber main body 10. With the injection of dimethyl ether, the pressure monitored by the third pressure sensor 13 rises to P1 (about 1 MPa) at time t1. Since the second proportional pressure valve 23 is set to 0.5 MPa, and the pressure in the pressure vessel main body 1 is 0.5 MPa, when the pressure in the constant volume chamber main body 10 rises to P1, the front and rear pressure difference is greater than 0.5 MPa, the second proportional pressure valve 23 automatically opens, and nitrogen and liquid dimethyl ether flow into the pressure vessel main body 1, and nitrogen begins to be discharged from the exhaust valve 7; the tested dimethyl ether injector 11 remains fully open. Since the second proportional pressure valve 23 is open, the pressure in the constant volume chamber main body 10 monitored by the third pressure sensor 13 remains P1 until t2 is reached.

[0083] S2.3: Starting from time t2, the tested dimethyl ether injector 11 continuously performs N injections at the maximum injection amount. After each of the aforementioned N-1 injections, the controller adjusts the pressure of the second proportional pressure valve 23 so that the pressure monitored by the third pressure sensor 13 approaches the set value P2 (about 1.5MPa). After multiple adjustments, after the Nth injection, the controller does not change the pressure of the second proportional pressure valve 23, and the pressure monitored by the third pressure sensor 13 stabilizes at P2. This is time t3, at which point the minimum back pressure is established; continue to perform M injections continuously at the maximum injection amount. After each injection, the pressure monitored by the third pressure sensor 13 stabilizes at P2 without changing the pressure of the second proportional pressure valve 23, indicating that the exhaust is completed. This is time t4.

[0084] S2.4: Under the control of the controller, close first proportional pressure valve 16 and pressure-reducing injector 17. Tested dimethyl ether injector 11 performs a single injection at maximum injection volume. After injection, the pressure is reduced to P3 by adjusting first proportional pressure valve 16 and opening pressure-reducing injector 17, with P3 > P2. Repeat S times, each time reducing pressure to P3 while changing first proportional pressure valve 16 and pressure-reducing injector 17, indicating that the injection back pressure during the test is established. This is time t5.

[0085] S3: Get the injection pattern (see Figure 3 ).

[0086] S3 specifically includes the following steps:

[0087] S3.1: A compression-ignition engine cam generates a "6+1" tooth signal, with a multi-tooth signal between teeth 1 and 2. This multi-tooth signal is separated from tooth 1 by 15° CA (cam angle).

[0088] S3.2: The falling edge of tooth 1 sends a "pressure regulation signal" to the controller. After receiving the pressure regulation signal, the controller controls the pressure of the first proportional pressure valve 16 to be increased to 5MPa to prevent the first proportional pressure valve 16 from opening after the constant volume chamber body 10 sprays dimethyl ether; at the same time, the controller sends an "acquisition signal" to the data acquisition card, and the data acquisition card collects the data monitored by the second pressure sensor 12.

[0089] S3.3: The falling edge of the multi-tooth sends an "injection signal" to the controller. After receiving the injection signal, the controller controls the tested dimethyl ether injector 11 to inject dimethyl ether in any amount. The injection pulse width must end before the falling edge of the tooth 4 signal, that is, the maximum injection pulse width is 165°CA.

[0090] S3.4: The falling edge of tooth 4 sends an "integration signal" to the controller. After receiving the integration signal, the controller monitors the data of the third pressure sensor 13 and the set pressure of the first proportional pressure valve 16, and simultaneously controls the mass flow meter to perform flow integration and stop collecting data from the second pressure sensor 12; the data acquisition card transmits the collected data from the second pressure sensor 12 to the industrial computer, which performs low-pass filtering and differential integration on the data to obtain a waveform of the injection pattern.

[0091] S4: Measure the injection amount.

[0092] After the falling edge of tooth 4 is triggered, the controller first adjusts the control pressure of the first proportional pressure valve 16 to 3MPa to relieve the pressure and accumulate the dimethyl ether injection amount; before the falling edge of tooth 6 arrives, the pressure reducing injector 17 is used for multiple injections to reduce the pressure data of the third pressure sensor 13 to P3. During this process, the mass flow meter 22 monitors the flow rate. The total discharge amount during the decompression process is the injection amount this time. The falling edge of tooth 6 sends a "stop signal" to the controller. After receiving the stop signal, the controller controls the mass flow meter 22 to stop accumulation, and the injection amount measurement ends.

[0093] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A device for measuring the injection pattern and injection amount of a large-flow dimethyl ether injector, characterized in that: It includes a constant volume chamber assembly, a pipeline valve assembly, a pressure vessel assembly and a control assembly; wherein the constant volume chamber assembly includes: a constant volume chamber body (10); The dimethyl ether injector (11) to be tested is installed on the constant volume chamber body (10); The second pressure sensor (12) and the third pressure sensor (13) are both installed on the constant volume chamber body (10); A nitrogen purge interface (29) is provided on the constant volume chamber body (10); Pressure vessel components include: Pressure vessel body (1); an exhaust valve (7), mounted on the pressure vessel body (1), for exhausting nitrogen; A gas phase return port (9) is provided on the pressure vessel body (1) for discharging dimethyl ether vapor; Pipeline valve components include: A first liquid return pipe, one end of which is fixedly connected to and communicates with the constant volume chamber body (10), and the other end of which is fixedly connected to and communicates with the pressure vessel body (1); a first proportional pressure valve (16), a fourth pressure sensor (20), a throttle valve (21), a mass flow meter (22), a second proportional pressure valve (23), a filter (24), and a first liquid return valve (5) are sequentially installed on the first liquid return pipe in the direction of dimethyl ether flow in the first liquid return pipe; A pressure regulating pipe is installed on the first liquid return pipe and is in communication with the first liquid return pipe; its two ends are connected to both sides of the first proportional pressure valve (16); a pressure reducing ejector (17) is installed on the pressure regulating pipe; The control component includes a controller (31) and a data acquisition card (30).

2. The device for measuring the injection pattern and injection amount of a large-flow dimethyl ether injector according to claim 1, characterized in that: A second liquid return pipe is connected between the constant volume chamber body (10) and the pressure vessel body (1), one end of which is fixedly connected to and communicated with the constant volume chamber body (10), and the other end of which is fixedly connected to and communicated with the pressure vessel body (1); a safety valve (15) and a second liquid return valve (6) are installed on the second liquid return pipe.

3. The device for measuring the injection pattern and injection amount of a large-flow dimethyl ether injector according to claim 2, characterized in that: A cooling water circulation water path is provided inside the wall panel of the constant volume chamber body (10), and a cooling water inlet (25) and a cooling water return port (28) are provided on the wall panel of the constant volume chamber body (10); the cooling water inlet (25) is externally connected to cooling water below 20° C., and a cooling water return check valve (26) and a cooling water reflux switch (27) are installed on the pipeline of the cooling water return port (28).

4. The device for measuring the injection pattern and injection amount of a large-flow dimethyl ether injector according to claim 3, characterized in that: A heat exchanger (18) is installed on the first liquid return pipe, and cooling water with a temperature not higher than 20° C. is passed into the heat exchanger (18) to ensure that the temperature of the dimethyl ether flowing through the mass flow meter (22) is stable and does not exceed 30° C.

5. The device for measuring the injection pattern and injection amount of a large-flow dimethyl ether injector according to claim 4, characterized in that: The bottom surface of the cavity of the constant volume chamber body (10) is a conical bottom surface.

6. A method for measuring the injection pattern and injection amount of a large-flow dimethyl ether injector, based on the device for measuring the injection pattern and injection amount of a large-flow dimethyl ether injector according to claim 5, characterized in that: The following steps are involved: S1: nitrogen purge; S2: injection back pressure is established; Among them, S2 specifically includes the following steps: S2.1: Under the control of the controller (31), the first liquid return valve (5), the second liquid return valve (6) and the exhaust valve (7) are opened, the first proportional pressure valve (16) and the pressure reducing ejector (17) are fully opened, the pressure of the second proportional pressure valve (23) is set to 0.5 MPa, and the gas phase return port (9) is closed; at this time, which is time t0, the third pressure sensor (13) monitors the pressure in the constant volume chamber body (10), and sets the pressure in the constant volume chamber body (10) at this time to P0; S2.2: At time t0, the nitrogen pressure in the constant volume chamber body (10) is P0, the dimethyl ether injector (11) to be tested is fully opened, and high-pressure dimethyl ether is sprayed into the constant volume chamber body (10). As the dimethyl ether is injected, the pressure monitored by the third pressure sensor (13) rises to P1 at time t1. Since the pressure difference before and after the second proportional pressure valve (23) is greater than 0.5 MPa, the second proportional pressure valve (23) automatically opens, and nitrogen and liquid dimethyl ether flow into the pressure vessel body (1), and nitrogen begins to be discharged from the exhaust valve (7); the dimethyl ether injector (11 to be tested) remains fully opened. Since the second proportional pressure valve (23) is open, the pressure in the constant volume chamber body (10) monitored by the third pressure sensor (13) remains P1 until reaching t2; S2.3: Starting from time t2, the tested dimethyl ether injector (11) continuously performs N injections at the maximum injection amount. After each of the aforementioned N-1 injections, the controller (31) adjusts the pressure of the second proportional pressure valve (23) so that the pressure monitored by the third pressure sensor (13) approaches the set value P2. After multiple adjustments, after the Nth injection, the controller does not change the pressure of the second proportional pressure valve (23), and the pressure monitored by the third pressure sensor (13) stabilizes at P2. This is time t3, at which the minimum back pressure is established. Continue to perform M injections at the maximum injection amount. After each injection, if the pressure monitored by the third pressure sensor (13) stabilizes at P2 without changing the pressure of the second proportional pressure valve (23), it indicates that the exhaust is completed. This is time t4. S2.4: Under the control of the controller (31), the first proportional pressure valve (16) and the pressure reducing injector (17) are closed; the tested dimethyl ether injector (11) performs a single injection according to the maximum injection amount. After the injection is completed, the pressure of the first proportional pressure valve (16) is adjusted and the pressure reducing injector (17) is opened to reduce the pressure to P3, where P3>P2; this is repeated S times, and the pressure is reduced to P3 each time while changing the first proportional pressure valve (16) and the pressure reducing injector (17), indicating that the injection back pressure is established; this is time t5; S3: Get the injection pattern; S4: Measure the injection amount.

7. The method for measuring the injection pattern and injection amount of a large-flow dimethyl ether injector according to claim 6, characterized in that: Step S1 includes the following steps: S1.1: Under the control of the controller (31), the dimethyl ether injector (11), the second proportional pressure valve (23), the exhaust valve (7), the gas phase return port (9), and the second liquid return valve (6) are all closed, the first proportional pressure valve (16) and the pressure reducing injector (17) are fully opened, and the first liquid return valve (5) is opened; S1.2: After the operator connects the nitrogen purge interface (29) to 0.8 MPa nitrogen, the gas phase return port (9) is opened, and the second proportional pressure valve (23) is fully opened; the dimethyl ether residual liquid in the constant volume chamber body (10) is blown into the pressure vessel body (1) by the nitrogen, and at the same time, the dimethyl ether vapor and nitrogen in the pressure vessel body (1) are discharged from the gas phase return port (9); S1.3: When the controller (31) detects that the value of the fourth pressure sensor (20) is stable, the controller (31) first closes the gas phase return port (9), then opens the exhaust valve (7), and finally closes the first liquid return valve (5); the nitrogen purge process is now complete.

8. The method for measuring the injection pattern and injection amount of a large-flow dimethyl ether injector according to claim 7, characterized in that: Step S3 includes the following steps: S3.1: The compression ignition engine cam generates a "6+1" tooth signal, with a multi-tooth signal between teeth 1 and 2. This multi-tooth signal is separated from tooth 1 by 15° CA. CA stands for cam angle. S3.2: The falling edge of tooth 1 sends a "pressure regulating signal" to the controller (31). After receiving the pressure regulating signal, the controller (31) controls the pressure of the first proportional pressure valve (16) to be increased to 5 MPa to prevent the first proportional pressure valve (16) from opening after dimethyl ether is sprayed from the constant volume chamber body (10). At the same time, the controller (31) sends a "collection signal" to the data acquisition card (30), and the data acquisition card (30) collects the data monitored by the second pressure sensor (12). S3.3: The falling edge of the multi-tooth sends an "injection signal" to the controller (31). After receiving the injection signal, the controller (31) controls the tested dimethyl ether injector (11) to inject dimethyl ether in any amount. The injection pulse width must end before the falling edge of the tooth 4 signal, that is, the maximum injection pulse width is 165°CA; S3.4: The falling edge of tooth 4 sends an "integration signal" to the controller (31). After receiving the integration signal, the controller (31) monitors the data of the third pressure sensor (13) and the set pressure of the first proportional pressure valve (16), and simultaneously controls the mass flow meter (22) to perform flow integration and stop collecting data from the second pressure sensor (12); the data acquisition card (30) transmits the collected data from the second pressure sensor (12) to the industrial control computer (32), and the industrial control computer (32) performs low-pass filtering and differential integration on the data to obtain a waveform of the injection regularity.

9. The method for measuring the injection pattern and injection amount of a large-flow dimethyl ether injector according to claim 8, characterized in that: Step S4 includes: after the falling edge of tooth 4 is triggered, the controller (31) first adjusts the control pressure of the first proportional pressure valve (16) to 3MPa to relieve pressure and accumulate the dimethyl ether injection amount. Before the falling edge of tooth 6 arrives, multiple injections are performed through the pressure reducing injector (17) to reduce the pressure data of the third pressure sensor (13) to P3; during this process, the mass flow meter (22) monitors the flow rate, and the total discharge amount during the pressure reduction process is the injection amount of this time. The falling edge of tooth 6 sends a "stop signal" to the controller (31). After receiving the stop signal, the controller (31) controls the mass flow meter (22) to stop accumulating, and the injection amount measurement ends.

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