Fuel supply and return system capable of automatically switching pressure working conditions

Abstract

The application discloses an oil supply and return system capable of automatically switching pressure working conditions, comprising an oil supply and return system I and an oil supply and return system II; the oil supply and return system I comprises fuel temperature control-pressure regulating switching-oil circulation functions, and integrates oil supply temperature control, oil supply pressure regulating switching, oil return cooling, oil return pressure regulating switching, circulating overflow, oil return exhaust, and a test object oil return collecting and processing component; the oil supply and return system II comprises oil circulation switching-pipeline sealing detection-fuel purging functions, and integrates circulating oil supply and return and test object oil return switching control valve groups, and pipeline sealing detection components under fuel pre-charging pressure. The application integrates oil supply temperature control, oil return cooling and gas removal, oil supply and return branch pressure switching control, fuel bidirectional purging, and a recovery component suitable for a laboratory oil supply system. The system adopts an integrated principle and structure, and the function modules are convenient for flexible configuration and expansion, so that the control requirements of users for oil circulation diversification of an engine hot test platform are met.

Description

Technical Field

[0001] This invention belongs to the technical field of engine testing platforms, fuel pressure regulation, and fuel circulation control methods for hot test benches. Specifically, it is a fuel supply and return system that automatically switches pressure conditions. Background Technology

[0002] In engine testing platforms, the fuel circulation system is an essential piece of equipment, ensuring stable fuel supply for engine operation. Its basic configuration includes: a fuel venting mechanism, a fuel supply pump, a fuel supply pressure regulating valve, and a return fuel circulation system. Higher-performance testing platforms may also include fuel supply temperature control and a return fuel pressure regulating valve. In engine factory hot-testing platforms, due to short production cycles, the test subject and testing equipment need frequent docking, testing, and disengagement. The system has a high degree of automation, and the fuel circulation system operates repeatedly and continuously under various operating conditions and rapid control states. This necessitates not only the configuration of fuel supply and return circulation and pressure regulating mechanisms, but also the implementation of internal engine purging and fuel recovery and reuse, placing considerable demands on system integration and control strategy development.

[0003] Domestic manufacturers typically employ a multi-unit approach: fuel temperature control, supply and return pressure regulation, fuel purging, and fuel recovery are each separately configured in cabinets, resulting in low integration and essentially operating the system independently. This approach is suitable for performance testing platforms with relatively simple test subjects and ample space; however, it is unsuitable for compact hot-testing platforms, considering the diverse test subject models, varied testing conditions, stability, and safety considerations. Imported manufacturers' solutions for hot-testing platform fuel circulation systems often utilize integrated modules: fuel temperature control, supply and return pressure regulation, circulation exhaust, and fuel recovery are connected via complex piping and mounted on a modular platform. This results in a compact structure, high space utilization, and convenient centralized operation and maintenance. However, their technical solutions are rigid, unable to flexibly respond to the customized technical requirements of domestic users, have excessively long design and debugging cycles, and involve expensive system components, leading to operating costs several times higher than domestic equipment. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes an automatic pressure-switching fuel supply and return system, integrating fuel supply temperature control, return fuel cooling and degassing, fuel supply and return line pressure switching control, bidirectional fuel purging, and a recovery component adapted to laboratory fuel supply systems. The system adopts an integrated principle and structure, with functional modules that allow for flexible configuration and expansion, meeting the diverse fuel circulation control needs of users for engine hot-testing platforms.

[0005] This invention is achieved through the following technical solution: A fuel supply and return system that automatically switches pressure conditions includes a fuel supply and return system I and a fuel supply and return system II; The oil supply and return system I includes fuel temperature control, pressure regulation switching, and fuel circulation functions, and integrates components for oil supply temperature control, oil supply pressure regulation switching, oil return cooling, oil return pressure regulation switching, circulation overflow, oil return venting, and sample blowback oil collection and processing. The oil supply and return system II includes fuel circulation switching, pipeline sealing detection, and fuel purging functions. It integrates a control valve group for switching between circulating oil supply and return and test subject purging oil, as well as a pipeline sealing detection component under fuel pre-charge pressure.

[0006] Furthermore, the pressure-regulating fuel supply output of the fuel supply and return system I is connected to the fuel supply pipe of the fuel supply and return system II through the fuel supply interface, and the return fuel input of the fuel supply and return system I is connected to the return fuel pipe of the fuel supply and return system II through the return fuel interface, thus establishing a fuel circulation system. The oil supply and return system I is connected to the oil outlet, oil return port, and exhaust port of the fuel consumption measuring instrument through external fuel interface I, external fuel interface II, and external fuel interface III, respectively. The oil supply and return system I is connected to the laboratory chilled water return and chilled water inlet through external system circulating water interface I and external system circulating water interface II, respectively. The oil supply and return system II connects to the fuel inlet and return outlet of the test subject through external fuel quick interface I and external fuel quick interface II, respectively. The test subject engine is mounted on a hot test tray and is quickly transferred to the test platform, where it is connected to the fuel inlet and outlet. The oil supply and return system II is connected to the laboratory compressed air supply through the external compressed air interface I and the external compressed air interface II as the fuel purging air source for the test subject, and another air source supplies the safety shut-off valve at the front end of the fuel consumption measuring instrument.

[0007] Furthermore, chilled water enters the external circulating water interface II of the system, passes through the filter and enters the oil supply heat exchanger C port. After exchanging heat with the fuel oil, it flows out from its D port, flows through the regulating valve V01 to control the return water flow, and then connects to the chilled water return from the external circulating water interface I of the system. After being measured by the fuel consumption meter, the fuel supplied to the laboratory flows into the external fuel interface I of the system. Then, it is pumped into the fuel supply heat exchanger A by the fuel pump P01. After heat exchange and adjustment to reach the target temperature, the fuel flows out from the fuel supply heat exchanger B. The sensor T01 monitors the fuel temperature value and feeds back the closed-loop control signal, automatically adjusting the opening of the valve V01. After temperature control, the fuel passes through the diversion pipeline and enters the multi-path pressure regulation control branch.

[0008] Furthermore, the multi-path pressure regulation control branch is divided into 3 paths. The first path allows fuel to flow through the on / off valve V03, the pressure regulating valve V06, the pressure gauge PG01, and the pressure sensor PS01 to provide fuel pressure for the engine pre-filling condition. The second fuel flow passes through the on / off valve V04, the pressure regulating valve V07, the pressure gauge PG02, and the pressure sensor PS02 to provide fuel pressure for the operating conditions of the Type I engine; The third fuel flow passes through the on / off valve V05, pressure regulating valve V08, pressure gauge PG03, and pressure sensor PS03 to provide fuel pressure for the operation of the Type II engine. After the multiple fuel pressures are regulated, they are combined into one fuel supply line, which is connected to the fuel supply interface of the fuel supply and return system II.

[0009] Furthermore, chilled water enters the external circulating water interface II of the system, passes through the filter, and enters the return oil heat exchanger C port. After exchanging heat with the fuel, it flows out from its D port and then connects to the chilled water return interface I of the system. The engine return oil is connected to the return oil interface of the supply and return oil system II. After being filtered by the fuel filter, it enters the return oil heat exchanger A port and is drawn out from the return oil heat exchanger B port by the fuel pump PO2. The cooled fuel passes through the split pipeline and enters the multi-path pressure regulating control branch.

[0010] Furthermore, the multi-channel voltage regulation control branch is divided into two channels; The first fuel flow passes through the on / off valve V09, pressure sensor PS04, pressure gauge PG04, and pressure regulating valve V11, providing return oil pressure for the operating conditions of the Type I engine; The second fuel flow passes through the on / off valve V10, pressure sensor PS05, pressure gauge PG05, and pressure regulating valve V12, providing return oil pressure for the Type II engine's operating conditions.

[0011] Furthermore, at the B port of the oil supply heat exchanger and the combined outlet of the return oil pressure regulating valve V11 and the return oil pressure regulating valve V12, the inlet and outlet of the pressure regulating valve V02 are connected respectively to adjust and establish the basic pressure of the oil supply circuit, and the fuel circulation overflow is uniformly connected to the exhaust tank G01. The return oil collected in the exhaust tank G01 is connected to the return oil port of the fuel consumption measuring instrument through the external fuel interface II of the system. The exhaust tank G01 is equipped with a liquid level sensor S01. When the return oil level is lower than the limit, the system controls the exhaust valve V13 to open, and the gas is connected to the exhaust port of the fuel consumption measuring instrument through the external fuel interface III of the system to realize high-level automatic exhaust.

[0012] Furthermore, the oil supply and return system I is also equipped with a collection tank G02. The blow-back oil passes through the blow-back interface of the oil supply and return system II and the purge and recovery interface of the collection tank G02, enters the collection tank G02 for sedimentation and filtration treatment, and is then extracted by the fuel pump P03. After passing through the check valve and the external fuel recovery interface of the system, it is pumped back to the test chamber for fuel supply. The collection tank G02 is equipped with a liquid level sensor S02. When the returned oil level is higher than the upper limit, the system controls the fuel pump P03 to start; when the liquid level is lower than the lower limit, the system controls the fuel pump P03 to shut down. The collection tank G02 is equipped with a venting mechanism. The system controls the opening and closing of the on / off valve V14 in stages. The mixed oil and gas enters the separator F01. After processing, the fuel sinks back to the collection tank G02, and the exhaust rises and connects to the inlet of the exhaust valve V13. When the system controls the exhaust valve V13 to be turned on, the gas is connected to the exhaust port of the fuel consumption measuring instrument through the external fuel interface III of the system, realizing high-level automatic venting.

[0013] Furthermore, the pressure-regulated fuel supplied by the fuel supply and return system I flows through the fuel supply interface, control valve V15, pressure gauge PG06 and pressure sensor PS06, and external fuel quick interface I before entering the engine. During engine test runs, the return oil flows through the external fuel quick-connect interface II, pressure gauge PG07 and pressure sensor PS07, control valve V16, return oil interface, and back to the return oil input of the supply and return oil system I; After the fuel supply and return circulation is connected, the system control valves V15 and V16 are closed. The engine and fuel system pipeline sealing is checked by the local pressure gauge value or the feedback from the remote pressure sensor. After the engine completes the working condition test, the system control valves V15 and V16 are closed, and two bidirectional oil blowing is performed.

[0014] Furthermore, the two-way bidirectional oil blowing is specifically as follows: Compressed air flows through the external compressed air interface I, check valve, and fluid control valve V17 of the system, and then through the fuel supply line - external fuel quick interface I of the system - engine - external fuel quick interface II of the system. Control valve V19 is closed and control valve V20 is opened, and the fuel stored in the engine is blown back once. Compressed air flows through the external compressed air interface II, check valve, and fluid control valve V18, then through the return oil pipe - external fuel quick interface II - engine - external fuel quick interface I. Control valve V19 opens and control valve V20 closes, allowing the oil stored inside the engine to be blown back a second time.

[0015] The beneficial effects of this invention are as follows: (1) This invention is applicable to hot test platforms and is a highly efficient integrated device for various functions of fuel supply and return circulation; (2) Benchmark against the advantages of competitors, simplify the front-end pressure stabilizing tank of the fuel consumption meter, and combine cost reduction by outsourcing and functional integration with forward development and design; (3) The present invention has a compact structure, makes full use of the laboratory space, and the installation areas of the two parts of the system are not restricted, which facilitates flexible installation of oil pipes; (4) Effectively utilize the pressure difference between the centralized fuel supply in the laboratory and the system recovery pump to achieve a closed-loop circulation of fuel on the hot test platform; (5) Facilitates the expansion of multiple oil circuits and multiple pressure indicators, and achieves pressure value coverage within a limited range; (6) The present invention can upgrade the pressure regulating valve to a pneumatic pressure regulating valve, and the fuel pressure monitoring can be upgraded to a transmitter with full pipeline configuration. The system can realize overall automatic closed-loop pressure cycle control. (7) This invention effectively improves the integration and safety stability of the fuel supply and return system, and facilitates centralized operation and maintenance; (8) On the basis of replacing the functions of imported equipment, it can flexibly respond to the technical customization requirements of domestic users, with a short design and debugging cycle, moderate prices of system components, and user matching and operation and maintenance costs far lower than those of imported equipment. Attached Figure Description

[0016] Figure 1 This is a general functional block diagram of the system of the present invention; Figure 2 This is a schematic diagram of part I of the oil supply and return system of the present invention; Figure 3 This is a schematic diagram of the supply and return oil system II of the present invention; Reference numerals: 1. External fuel quick-connect port I, 2. External fuel quick-connect port II, 3. External compressed air port I, 4. External compressed air port II, 5. External fuel port I, 6. External fuel port II, 7. External fuel port III, 8. External fuel recovery port, 9. External circulating water port I, 10. External circulating water port II. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0018] like Figure 1 As shown, a fuel supply and return system with automatic pressure switching includes two main parts: supply and return system I and supply and return system II. The oil supply and return system I includes fuel temperature control, pressure regulation switching, and fuel circulation functions, and integrates components for oil supply temperature control, oil supply pressure regulation switching, oil return cooling, oil return pressure regulation switching, circulation overflow, oil return venting, and sample blowback oil collection and processing. The oil supply and return system II includes fuel circulation switching, pipeline sealing detection, and fuel purging functions. It integrates a control valve group for switching between circulating oil supply and return and test subject purging oil, as well as a pipeline sealing detection component under fuel pre-charge pressure.

[0019] The pressure-regulating fuel supply output of the fuel supply and return system I is connected to the fuel supply pipe of the fuel supply and return system II through the fuel supply interface, and the return fuel input of the fuel supply and return system I is connected to the return fuel pipe of the fuel supply and return system II through the return fuel interface, thus establishing a fuel circulation system. The oil supply and return system I is connected to the oil outlet, oil return port, and exhaust port of the fuel consumption measuring instrument through external fuel interface I5, external fuel interface II6, and external fuel interface III7, respectively. The laboratory fuel supply passes through coarse filter, fine filter, safety shut-off valve, and pressure reducing valve, and the pressure is stabilized in the range of 0.08-0.12MPa before being supplied to the fuel consumption measuring instrument.

[0020] The oil supply and return system I is connected to the laboratory chilled water return (7-12℃) and chilled water inlet via external circulating water interface I9 and external circulating water interface II10, respectively. The fuel supply and return system II connects to the fuel inlet and return outlet of the test subject through external fuel quick interface I1 and external fuel quick interface II2, respectively. The test subject engine is installed on a hot test tray and quickly transferred to the test platform. The fuel inlet and outlet are connected, and the system establishes fuel circulation to adapt to the fuel supply adjustment index of the internal fuel pump of various types of engines.

[0021] The oil supply and return system II is connected to the laboratory compressed air supply (filtered, depressurized and dehydrated) through the external compressed air interface I3 and the external compressed air interface II4 as the fuel purging air source for the test subject, and another air source supplies the safety shut-off valve at the front end of the fuel consumption measuring instrument.

[0022] The principle of the oil supply and return system is as follows: Figure 2 As shown, the fuel supply section is as follows: Chilled water enters the external circulating water interface II10 of the system, passes through the filter and enters the oil supply heat exchanger C port. After exchanging heat with fuel oil, it flows out from its D port, flows through the regulating valve V01 to control the return water flow, and then connects to the chilled water return water from the external circulating water interface I9 of the system. After being measured by the fuel consumption meter, the fuel supplied to the laboratory flows into the external fuel interface I5 of the system. Then, it is pumped into the fuel supply heat exchanger A by the fuel pump P01. After heat exchange and adjustment to reach the target temperature, the fuel flows out from the fuel supply heat exchanger B. The sensor T01 monitors the fuel temperature value and feeds back the closed-loop control signal, automatically adjusting the opening of the valve V01. After temperature control, the fuel passes through the diversion pipeline and enters the multi-path pressure regulation control branch.

[0023] Furthermore, as shown in the figure, the multi-path pressure regulation control branch is divided into 3 paths. The first path allows fuel to flow through the on / off valve V03, the pressure regulating valve V06, the pressure gauge PG01, and the pressure sensor PS01 to provide fuel pressure for the engine pre-filling condition. The second fuel flow passes through the on / off valve V04, the pressure regulating valve V07, the pressure gauge PG02, and the pressure sensor PS02 to provide fuel pressure for the operating conditions of the Type I engine; The third fuel flow passes through the on / off valve V05, the pressure regulating valve V08, the pressure gauge PG03, and the pressure sensor PS03 to provide fuel pressure for the operation of the Type II engine. Similarly, after multiple fuel pressure regulation, they are combined into one fuel supply line, which is connected to the fuel supply interface of the fuel supply and return system II.

[0024] The return oil section specifically includes: Chilled water enters the system's external circulating water interface II10, passes through a filter, and then enters the return oil heat exchanger C port. After exchanging heat with the fuel, it flows out from its D port and then connects to the chilled water return water through the system's external circulating water interface I9. The engine return oil is connected to the return oil interface of the return oil supply system II. After being filtered by the fuel filter, it enters the return oil heat exchanger A port. The return oil is cooled by heat exchange to reduce air bubbles and is then drawn out by the fuel pump P02 from the return oil heat exchanger B port. The cooled fuel passes through the split pipeline and enters the multi-path pressure regulating control branch.

[0025] Furthermore, as shown in the figure, the multi-channel voltage regulation control branch is divided into two channels; The first fuel flow passes through the on / off valve V09, pressure sensor PS04, pressure gauge PG04, and pressure regulating valve V11, providing return oil pressure for the operating conditions of the Type I engine; The second fuel flow passes through the on / off valve V10, pressure sensor PS05, pressure gauge PG05, and pressure regulating valve V12 to provide return oil pressure for the operation of the Type II engine, and so on.

[0026] The fuel exhaust system is specifically as follows: At the B port of the oil supply heat exchanger and the combined outlet of the return oil pressure regulating valve V11 and the return oil pressure regulating valve V12, the inlet and outlet of the pressure regulating valve V02 are connected respectively to adjust and establish the basic pressure of the oil supply circuit, and the fuel circulation overflow is uniformly connected to the exhaust tank G01. The return oil collected in the exhaust tank G01 is connected to the return oil port of the fuel consumption measuring instrument through the external fuel interface II6 of the system. The exhaust tank G01 is equipped with a liquid level sensor S01. When the return oil level is lower than the limit, the system controls the exhaust valve V13 to open, and the gas is connected to the exhaust port of the fuel consumption measuring instrument through the external fuel interface III7 of the system to realize high-level automatic exhaust.

[0027] The fuel recovery section specifically includes: The oil supply and return system I is also equipped with a collection tank G02. The blow-back oil passes through the blow-back interface of the oil supply and return system II and the purge and recovery interface of the collection tank G02, and enters the collection tank G02 for sedimentation and filtration treatment. Then it is extracted by the fuel pump P03, and connected to the laboratory fuel supply pipeline or the test recovery oil tank through the check valve and the external fuel recovery interface 8. The pressure of the laboratory fuel supply pipeline is 0.2-0.3MPa. The collection tank G02 is equipped with a liquid level sensor S02. When the returned oil level is higher than the upper limit, the system controls the fuel pump P03 to start; when the liquid level is lower than the lower limit, the system controls the fuel pump P03 to shut down. The collection tank G02 is equipped with a venting mechanism. The system controls the opening and closing of the on / off valve V14 in stages. The mixed oil and gas enters the separator F01. After processing, the fuel sinks back to the collection tank G02, and the exhaust rises and connects to the inlet of the exhaust valve V13. When the system controls the exhaust valve V13 to be turned on, the gas is connected to the exhaust port of the fuel consumption measuring instrument through the external fuel interface Ⅲ7 of the system to realize high-level automatic venting.

[0028] Furthermore, the principle of the supply and return oil system II is as follows: Figure 3 As shown: The pressure-regulated fuel output from the fuel supply and return system I flows through the fuel supply interface, control valve V15, pressure gauge PG06 and pressure sensor PS06, and external fuel quick interface I1 before entering the engine; During engine test runs, the return oil flows through the external fuel quick-connect interface II2, pressure gauge PG07 and pressure sensor PS07, control valve V16, return oil interface, and back to the return oil input of the supply and return oil system I; After the fuel supply and return circulation is connected, the system control valves V15 and V16 (i.e., system operation control valves V15 and V16) are closed. The engine and fuel system pipeline sealing is checked by feedback from the local pressure gauge or remote pressure sensor. After the engine completes the operating condition test, the system control valves V15 and V16 are closed, and two bidirectional oil blowing occurs.

[0029] Furthermore, the two-way bidirectional oil blowing is specifically as follows: Compressed air flows through the external compressed air interface I3, check valve, and fluid control valve V17 of the system, and then through the fuel supply line - external fuel quick interface I1 of the system - engine - external fuel quick interface II2 of the system. Control valve V19 is closed and control valve V20 is opened, and the fuel stored in the engine is blown back once. Compressed air flows through the external compressed air interface II4, check valve, and fluid control valve V18, then through the return oil pipe - external fuel quick interface II2 - engine - external fuel quick interface I1. Control valve V19 opens and control valve V20 closes, allowing the oil stored inside the engine to be blown back a second time.

[0030] This automatic pressure switching fuel supply and return system has been put into production in multiple sets. After actual application in the user's hot test platform laboratory, it has been running for more than 2 years, delivering fuel to more than 10,000 engines of various models. The cycle switching is smooth, the fuel pressure regulation is stable, and the fuel recovery is efficient and safe, meeting the user's diverse fuel cycle control needs for the engine hot test platform.

[0031] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope. All such changes and modifications fall within the scope of the present invention as claimed, which is defined by the appended claims and their equivalents.

Claims

1. A fuel supply and return system that automatically switches pressure conditions, characterized in that: Includes oil supply and return system I and oil supply and return system II; The oil supply and return system I includes fuel temperature control, pressure regulation switching, and fuel circulation functions, and integrates components for oil supply temperature control, oil supply pressure regulation switching, oil return cooling, oil return pressure regulation switching, circulation overflow, oil return venting, and sample blowback oil collection and processing. The fuel supply and return system II includes fuel circulation switching, pipeline sealing detection, and fuel purging functions. It integrates a control valve group for switching between circulating fuel supply and return and test subject purging, and a pipeline sealing detection component under fuel pre-charge pressure. The pressure-regulating fuel supply output from the fuel supply and return system I is connected to the fuel supply pipe of the fuel supply and return system II through the fuel supply interface. The return fuel input of the fuel supply and return system I is connected to the return fuel pipe of the fuel supply and return system II through the return fuel interface, thus establishing a fuel circulation system. The oil supply and return system I is connected to the oil outlet, oil return port, and exhaust port of the fuel consumption measuring instrument through external fuel interface I (5), external fuel interface II (6), and external fuel interface III (7), respectively. The oil supply and return system I is connected to the laboratory chilled water return and chilled water inlet through the external circulating water interface I (9) and the external circulating water interface II (10), respectively; the oil supply and return system II is connected to the fuel inlet and oil return outlet of the test subject through the external fuel quick interface I (1) and the external fuel quick interface II (2), respectively. The test subject engine is installed on the hot test tray and is quickly transferred to the test platform and connected to the fuel inlet and outlet. The oil supply and return system II is connected to the laboratory compressed air supply through the external compressed air interface I (3) and the external compressed air interface II (4) as the test fuel purging air source. Another air source supplies the safety shut-off valve at the front end of the fuel consumption measuring instrument. The chilled water inlet flows into the external circulating water interface II (10), enters the oil supply heat exchanger C port after passing through the filter, exchanges heat with the fuel and flows out from its D port, flows through the regulating valve V01 to control the return water flow, and then connects to the chilled water return water through the external circulating water interface I (9). After being measured by the fuel consumption meter, the fuel supplied to the laboratory flows into the external fuel interface I (5) of the system. Then, it is pumped into the fuel supply heat exchanger A by the fuel pump P01. After heat exchange and adjustment, the fuel reaches the target temperature and flows out from the fuel supply heat exchanger B. The sensor T01 monitors the fuel temperature value and feeds back the closed-loop control signal, automatically adjusting the opening of the regulating valve V01. After temperature control, the fuel passes through the diversion pipeline and enters the multi-path pressure regulation control branch.

2. The fuel supply and return system with automatic pressure switching according to claim 1, characterized in that: The multi-path pressure regulation control branch is divided into 3 paths. The first path is fuel flowing through the on-off valve V03, the pressure regulating valve V06, the pressure gauge PG01 and the pressure sensor PS01 to provide fuel pressure for the engine pre-filling condition. The second fuel flow passes through the on / off valve V04, the pressure regulating valve V07, the pressure gauge PG02, and the pressure sensor PS02 to provide fuel pressure for the operating conditions of the Type I engine; The third fuel flow passes through the on / off valve V05, pressure regulating valve V08, pressure gauge PG03, and pressure sensor PS03 to provide fuel pressure for the operation of the Type II engine. After the multiple fuel pressures are regulated, they are combined into one fuel supply line, which is connected to the fuel supply interface of the fuel supply and return system II.

3. The fuel supply and return system with automatic pressure switching according to claim 1, characterized in that: Chilled water enters the external circulating water interface II (10) of the system, passes through the filter and enters the return oil heat exchanger C port. After exchanging heat with the fuel, it flows out from its D port and then connects to the chilled water return from the external circulating water interface I (9). The engine return oil is connected to the return oil interface of the return oil supply system II. After being filtered by the fuel filter, it enters the return oil heat exchanger A port and is drawn out from the return oil heat exchanger B port by the fuel pump P02. The cooled fuel passes through the split pipeline and enters the multi-path pressure regulating control branch.

4. The fuel supply and return system with automatic pressure switching according to claim 3, characterized in that: The multi-channel voltage regulation control branch is divided into two channels; The first fuel flow passes through the on / off valve V09, pressure sensor PS04, pressure gauge PG04, and pressure regulating valve V11, providing return oil pressure for the operating conditions of the Type I engine; The second fuel flow passes through the on / off valve V10, pressure sensor PS05, pressure gauge PG05, and pressure regulating valve V12, providing return oil pressure for the Type II engine's operating conditions.

5. The fuel supply and return system with automatic pressure switching according to claim 1, characterized in that: At the B port of the oil supply heat exchanger and the confluence outlet of the return oil pressure regulating valve V11 and the return oil pressure regulating valve V12, the inlet and outlet of the pressure regulating valve V02 are connected respectively to adjust and establish the basic pressure of the oil supply circuit, and the fuel circulation overflow is uniformly connected to the exhaust tank G01. The return oil collected by the exhaust tank G01 is connected to the return oil port of the fuel consumption measuring instrument through the external fuel interface II (6) of the system. The exhaust tank G01 is equipped with a liquid level sensor S01. When the return oil level is lower than the limit, the system controls the exhaust valve V13 to be turned on, and the gas is connected to the exhaust port of the fuel consumption measuring instrument through the external fuel interface Ⅲ (7) of the system to realize high-level automatic exhaust.

6. The fuel supply and return system with automatic pressure switching according to claim 1, characterized in that: The oil supply and return system I is also equipped with a collection tank G02. The blowback oil passes through the blowback interface of the oil supply and return system II and the purge and recovery interface of the collection tank G02, enters the collection tank G02 for sedimentation and filtration treatment, and is then extracted by the fuel pump P03. After passing through the check valve and the external fuel recovery interface (8) of the system, it is pumped back to the test chamber for fuel supply. The collection tank G02 is equipped with a liquid level sensor S02. When the returned oil level is higher than the upper limit, the system controls the fuel pump P03 to start; when the liquid level is lower than the lower limit, the system controls the fuel pump P03 to shut down. The collection tank G02 is equipped with a venting mechanism. The system controls the opening and closing of the on / off valve V14 in different time periods. The mixed oil and gas enter the separator F01. After processing, the fuel sinks back to the collection tank G02, and the exhaust rises and connects to the inlet of the exhaust valve V13. When the system controls the exhaust valve V13 to be turned on, the gas is connected to the exhaust port of the fuel consumption measuring instrument through the external fuel interface Ⅲ (7) of the system to realize high-level automatic exhaust.

7. The fuel supply and return system with automatic pressure switching according to claim 1, characterized in that: The pressure-regulated fuel output from the fuel supply and return system I flows through the fuel supply interface, control valve V15, pressure gauge PG06 and pressure sensor PS06, and external fuel quick interface I (1) of the system, and enters the engine. During engine test run, the return oil flows through the external fuel quick interface II (2), pressure gauge PG07 and pressure sensor PS07, control valve V16, return oil interface, and returns to the return oil input of the supply and return oil system I; After the fuel supply and return circulation is connected, the system control valves V15 and V16 are closed. The engine and fuel system pipeline sealing is checked by the local pressure gauge value or the feedback from the remote pressure sensor. After the engine completes the working condition test, the system control valves V15 and V16 are closed, and two bidirectional oil blowing is performed.

8. The fuel supply and return system with automatic pressure switching according to claim 7, characterized in that: The two-way oil blowing process is as follows: Compressed air flows through the external compressed air interface I (3), check valve, and fluid control valve V17 of the system, and then through the oil supply pipe - external fuel quick interface I (1) of the system - engine - external fuel quick interface II (2) of the system. Control valve V19 is closed and control valve V20 is opened, and the oil stored in the engine is blown back once. Compressed air flows through the external compressed air interface II (4), check valve, and fluid control valve V18 of the system, and then through the return oil pipe - external fuel quick interface II (2) of the system - engine - external fuel quick interface I (1) of the system. Control valve V19 is opened and control valve V20 is closed, and the oil stored in the engine is blown back for the second time.

Images