Device and method for testing airtightness of LGIM host component

Abstract

The invention discloses a device and a method for testing the airtightness of an LGIM host component. The device comprises a nitrogen loop, a hydraulic oil loop, a compressed air loop and a water loop, the nitrogen loop comprises a nitrogen input port, a nitrogen output port and a nitrogen return port; the hydraulic oil loop comprises an oil storage tank, a low-pressure make-up oil supply pump, a high-pressure sealing oil pump, a high-pressure control oil pump, a low-pressure sealing oil pump, a main engine sealing oil pump, a low-pressure make-up oil output port, a high-pressure sealing oil output port, a high-pressure control oil output port and a low-pressure sealing oil output port, the hydraulic oil circuit comprises a hydraulic oil output port, a main engine sealing oil output port and a test cavity oil return port, the water circuit comprises a water storage tank, a water inlet, a water return port, a water pressure pump and a water outlet, and the compressed air circuit is respectively connected with the hydraulic oil circuit and the water circuit and comprises a compressed air input port and a compressed air source treatment triple piece connected with the compressed air input port. According to the invention, hydraulic oil, water and gas with specified pressure are output to the host, completion of gas tightness detection is ensured, and the device has the advantages of simple operation, convenient maintenance and high reliability.

Description

Technical Field

[0001] The present invention relates to a marine low-speed diesel engine, and particularly to a device and a method for airtightness testing of LGIM main engine components, belonging to the technical field of diesel engine manufacturing. Background Art

[0002] In order to enable ships to comply with the IMO SOx emission regulations that came into effect globally in 2020, MAN has launched a dual-fuel liquefied petroleum gas ME-LGIM engine under this background. Since methanol has a low boiling point and is toxic itself, the ME-LGIM main engine has very strict requirements for airtightness. In order to ensure the safety of the marine low-speed diesel engine during operation, after the LGIM main engine cylinder head and fuel block are installed, pump pressure and function tests must be carried out. The purpose is to check the installation of the cylinder head and fuel block, check for leaks, and check whether the inlet and outlet valves of the fuel block and the functional operation of the methanol injection valve are normal. Summary of the Invention

[0003] The purpose of the content of the present invention is to provide a device and a method for airtightness testing of LGIM main engine components, which are used to output hydraulic oil, water and gas at a specified pressure, so as to perform airtightness detection on the cylinder head and methanol control block of the installed LGIM dual-fuel main engine, achieving the effects of skid-mounted structure, convenient transportation, convenient operation, simple use and high system reliability.

[0004] Based on the above purpose, the technical solution of the present invention is as follows:

[0005] A device for airtightness testing of LGIM main engine components, which is connected to the main engine and provides a test medium during airtightness testing. It is characterized in that: the device includes a nitrogen circuit, a hydraulic oil circuit, a compressed air circuit and a water circuit;

[0006] The nitrogen circuit is used to supply nitrogen to the main engine, and includes a nitrogen input port, a nitrogen output port and a nitrogen return port; the nitrogen input port is connected to the nitrogen output port through a gas pressure reducing valve and a stop valve in sequence, the nitrogen output port and the nitrogen return port are respectively connected to corresponding interfaces of the main engine, and a safety valve is provided at the nitrogen output port;

[0007] The hydraulic oil circuit is used to supply hydraulic oil to the main engine, and includes an oil storage tank, a low-pressure supplementary oil supply pump, a high-pressure seal oil pump, a high-pressure control oil pump, a low-pressure seal oil pump, a main engine seal oil pump, and a low-pressure supplementary oil outlet, a high-pressure seal oil outlet, a high-pressure control oil outlet, a low-pressure seal oil outlet, a main engine seal oil outlet, and a test chamber oil return port that are respectively connected to corresponding interfaces of the main engine; the inlets of the low-pressure supplementary oil supply pump, the high-pressure seal oil pump, the high-pressure control oil pump, the low-pressure seal oil pump, the main engine seal oil pump, and the test chamber oil return port are respectively connected to the oil storage tank, and the outlets of the low-pressure supplementary oil supply pump, the high-pressure seal oil pump, the high-pressure control oil pump, the low-pressure seal oil pump, and the main engine seal oil pump are respectively connected to the low-pressure supplementary oil outlet, the high-pressure seal oil outlet, the high-pressure control oil outlet, the low-pressure seal oil outlet, and the main engine seal oil outlet through one-way valves, and are respectively connected to the oil return pipe leading to the oil storage tank through safety valves, and this oil return pipe is respectively connected to the inlets of the low-pressure supplementary oil supply pump, the high-pressure seal oil pump, the high-pressure control oil pump, the low-pressure seal oil pump, and the main engine seal oil pump through stop valves;

[0008] The water circuit is used to supply circulating water to the main engine, and includes a water storage tank, a water inlet, a water return port, a water pressurizing pump, and a water outlet; the water storage tank is respectively connected to the water inlet and the water return port, the inlet of the water pressurizing pump is connected to the water inlet through a one-way valve, and the outlet is connected to the water outlet through a one-way valve, this water outlet is connected to a corresponding interface of the main engine, and the outlet of the water pressurizing pump is also connected to the water return port through a safety valve, and a stop valve is connected in parallel with this safety valve;

[0009] The compressed air circuit is respectively connected to the hydraulic oil circuit and the water circuit, and is used to provide compressed air for controlling the low-pressure supplementary oil supply pump, the high-pressure seal oil pump, the high-pressure control oil pump, the low-pressure seal oil pump, the main engine seal oil pump, and the water pressurizing pump, and includes a compressed air inlet and a compressed air source treatment triple unit connected to this compressed air inlet, and this compressed air source treatment triple unit is respectively connected to the low-pressure supplementary oil supply pump, the high-pressure seal oil pump, the high-pressure control oil pump, the low-pressure seal oil pump, the main engine seal oil pump, and the water pressurizing pump through a gas stop valve and a gas pressure regulating valve in sequence.

[0010] As a further improvement, the oil storage tank is used to store hydraulic oil and is internally equipped with a permanent magnet to adsorb iron filings in the oil.

[0011] As a further improvement, the outlets of the high-pressure seal oil pump and the high-pressure control oil pump are connected to the oil return pipe leading to the oil storage tank through a two-way three-way valve for controlling pressure reduction.

[0012] As a further improvement, accumulators are connected to the outlets of the high-pressure control oil pump and the water pressurizing pump, and these accumulators have a voltage stabilizing and compensating effect.

[0013] As a further improvement, pressure gauges are provided at the inlets of the low-pressure supplementary oil supply pump, high-pressure seal oil pump, high-pressure control oil pump, low-pressure seal oil pump, main engine seal oil pump, and water pressurizing pump.

[0014] As a further improvement, the device is of a semi-enclosed skid-mounted structure, with a door on the outer shell, casters and lifting points installed at the lower part, and a compressed air filtering and drying device inside.

[0015] Another technical solution of the present invention is:

[0016] A method for airtightness testing of LGIM main engine components implemented by the above device, which includes the following steps:

[0017] 1) Fill the fuel tank with hydraulic oil, fill the water storage tank with water, connect the compressed air input port to an external compressed air source, connect the nitrogen input port to an external nitrogen cylinder, and connect the nitrogen output port, nitrogen return port, low-pressure supplementary oil output port, high-pressure seal oil output port, high-pressure control oil output port, low-pressure seal oil output port, main engine seal oil output port, test chamber oil return port, and water outlet to the corresponding interfaces on the main engine cylinder head gas components;

[0018] 2) Open all gas pressure regulating valves that control each oil pump in the compressed air circuit, boost the pressure of the hydraulic oil circuit, and at the same time adjust the oil pressure to a predetermined target value within the maximum pressure range;

[0019] 3) When the oil pressure of the hydraulic oil circuit reaches the predetermined target, open the stop valve in the nitrogen circuit. When the nitrogen pressure rises to the process-set target value, close the stop valve, and the main engine starts airtightness testing;

[0020] 4) After the test is completed, first open the stop valve in the nitrogen circuit for pressure relief. After the nitrogen is completely depressurized, open the stop valve in the hydraulic circuit for pressure relief, and the hydraulic oil flows back into the fuel tank;

[0021] 5) If an emergency occurs during the airtightness testing process, immediately open the stop valves in the hydraulic oil circuit and the nitrogen circuit, relieve the pressure of the circuit, and confirm whether the safety valves in the hydraulic oil circuit and the nitrogen circuit are working.

[0022] As a further improvement, in step 1), the input pressure of the compressed air inlet is 7 bar, the input pressure of the nitrogen inlet is 150 bar, the maximum pressure of the nitrogen output from the nitrogen output port to the main engine is 7 bar, the maximum pressure of the low-pressure supplementary oil output from the low-pressure supplementary oil output port to the main engine is 28 bar, the maximum pressure of the high-pressure seal oil output from the high-pressure seal oil output port to the main engine is 100 bar, the maximum pressure of the high-pressure control oil output from the high-pressure control oil output port to the main engine is 400 bar, the maximum pressure of the low-pressure seal oil output from the low-pressure seal oil output port to the main engine is 30 bar, the maximum pressure of the main engine seal oil output from the main engine seal oil output port to the main engine is 16 bar, and the maximum pressure of the circulating water output from the water outlet to the main engine is 13 bar.

[0023] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0024] 1. It can output hydraulic oil, water and gas with specified pressures to the LGIM dual-fuel main engine to smoothly complete the airtightness detection operation.

[0025] 2. The device adopts a semi-closed skid-mounted structure, which is convenient for equipment maintenance, movement and hoisting.

[0026] 3. The present invention has the advantages of convenient operation, simple use and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of the principle of the present invention.

[0028] In the figure, 1 - low-pressure supplementary oil supply pump, 2 - high-pressure seal oil pump, 3 - high-pressure control oil pump, 4 - low-pressure seal oil pump, 5 - main engine seal oil pump, 6 - water pressurizing pump, 7 - check valve, 8 - oil storage tank, 9 - compressed air source treatment triple unit, 10 - water storage tank, 11 - gas shut-off valve, 12 - gas pressure regulating valve, 13 - safety valve, 14 - pressure gauge, 15 - stop valve, 16 - check valve, 17 - two-position three-way valve, 18 - accumulator, 19 - air source pressure reducing valve, 20 - stop valve, 21 - accumulator, 22 - check valve, 23 - stop valve, 24 - nitrogen charging port of the accumulator, 25 - gas pressure reducing valve, 26 - silencer, 28 - safety valve, 29 - pressure gauge, 30 - pressure gauge. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The present invention will be further described in detail below with reference to the drawings and embodiments, but the scope of the present invention claimed cannot be limited thereby.

[0030] The present invention is used for the airtightness test of LGIM host components, providing media such as hydraulic oil, water, and gas for the test: supplying nitrogen for the simulated operation of the host methanol system, providing the required compressed air and hydraulic oil for driving to the cylinder head, and simulating fuel injection.

[0031] Please refer to Figure 1 , the airtightness test device is connected to the components of the LGIM host, and includes a nitrogen circuit, a hydraulic oil circuit, a compressed air circuit, and a water circuit.

[0032] The nitrogen circuit is used to supply nitrogen to the host, and includes a nitrogen input port, a nitrogen output port, and a nitrogen return port. The nitrogen input port is used to input nitrogen, and is connected to the nitrogen output port through a gas pressure reducing valve 25 and a stop valve 23 in sequence. The nitrogen output port and the nitrogen return port are respectively connected to the corresponding interfaces of the host. A pressure gauge 29, a pressure gauge 30, and a safety valve 28 are provided at the nitrogen output port. Among them, the pressure gauge 30 is a digital display pressure gauge, which is convenient for airtight detection. The safety valve 28 is connected with a silencer 26; a nitrogen charging port 24 for the accumulator is provided between the gas pressure reducing valve 25 and the nitrogen input port, and a nitrogen charging port 24 for the accumulator is provided between the gas pressure reducing valve 25 and the nitrogen output port and is connected to the silencer 26 through another stop valve 23. The nitrogen return port is connected to the silencer 26 through a gas source pressure reducing valve 19.

[0033] The hydraulic oil circuit is used to supply hydraulic oil to the host, and includes an oil storage tank 8, a low-pressure supplementary oil supply pump 1, a high-pressure seal oil pump 2, a high-pressure control oil pump 3, a low-pressure seal oil pump 4, a host seal oil pump 5, and a low-pressure supplementary oil output port, a high-pressure seal oil output port, a high-pressure control oil output port, a low-pressure seal oil output port, a host seal oil output port, and a test chamber oil return port that are respectively connected to the corresponding interfaces of the host.

[0034] The fuel tank 8 is used to store hydraulic oil and is internally equipped with permanent magnets to adsorb iron filings in the oil. The inlet of the low-pressure supplementary oil supply pump 1 is connected to the fuel tank 8, and the outlet is connected to the low-pressure supplementary oil outlet through the check valve 22. The inlet of the high-pressure seal oil pump 2 is connected to the fuel tank 8, and the outlet is connected to the high-pressure seal oil outlet through the check valve 22. The inlet of the high-pressure control oil pump 3 is connected to the fuel tank 8, and the outlet is sequentially connected to the high-pressure control oil outlet through the check valve 16 and the check valve 22. The inlet of the low-pressure seal oil pump 4 is connected to the fuel tank 8, and the outlet is sequentially connected to the low-pressure seal oil outlet through the check valve 16 and the check valve 22. The inlet of the main engine seal oil pump 5 is connected to the fuel tank 8, and the outlet is sequentially connected to the main engine seal oil outlet through the check valve 16 and the check valve 22. The outlets of the low-pressure supplementary oil supply pump 1, the high-pressure seal oil pump 2, the high-pressure control oil pump 3, the low-pressure seal oil pump 4, and the main engine seal oil pump 5 are respectively connected to the oil return pipe leading to the fuel tank 8 through the safety valve 13. The oil return pipe is respectively connected to the inlets of the low-pressure supplementary oil supply pump 1, the high-pressure seal oil pump 2, the high-pressure control oil pump 3, the low-pressure seal oil pump 4, and the main engine seal oil pump 5 through the stop valve 15, and pressure gauges 14 are provided at the inlets. The outlets of the high-pressure seal oil pump 2 and the high-pressure control oil pump 3 are connected to the oil return pipe leading to the fuel tank 8 through a two-position three-way valve 17 for controlling pressure reduction. The outlet of the high-pressure control oil pump 3 is also connected to an accumulator 18 with a pressure stabilizing and compensating function. The test chamber oil return port is connected to the corresponding interface of the main engine and is also connected to the fuel tank 8 for sending the circulating hydraulic oil from the main engine back to the fuel tank 8.

[0035] The water circuit is used to supply circulating water to the main engine and includes an external water storage tank 10, a water inlet, a water return port, a water pressure pump 6, a water outlet, and an accumulator 21.

[0036] The water storage tank 10 is respectively connected to the water inlet and the water return port. The inlet of the water pressure pump 6 is connected to the water inlet through the check valve 7, and the outlet is sequentially connected to the water outlet through the check valve 16 and the check valve 22. The water outlet is connected to the corresponding interface of the main engine. The accumulator 21 has a pressure stabilizing and compensating function and is connected between the check valve 16 and the check valve 22 through the stop valve 20, and a pressure gauge 14 is also connected. The outlet of the water pressure pump 6 is also connected to the water return port through the safety valve 13, and a stop valve 15 is connected in parallel with the safety valve 13.

[0037] The compressed air circuit is respectively connected to the hydraulic oil circuit and the water circuit, and is used to provide compressed air for controlling the low-pressure supplementary oil supply pump 1, high-pressure seal oil pump 2, high-pressure control oil pump 3, low-pressure seal oil pump 4, main engine seal oil pump 5 and water pressurizing pump 6 in two paths. It includes two compressed air inlets and two compressed air source treatment triplets 9 respectively connected to the two compressed air inlets. One of the compressed air source treatment triplets 9 is respectively connected to the low-pressure supplementary oil supply pump 1, high-pressure seal oil pump 2 and high-pressure control oil pump 3 through a gas stop valve 11 and a gas pressure regulating valve 12 in sequence. The other compressed air source treatment triplet 9 is respectively connected to the low-pressure seal oil pump 4, main engine seal oil pump 5 and water pressurizing pump 6 through a gas stop valve 11 and a gas pressure regulating valve 12 in sequence. The gas pressure regulating valve 12 can meet the working conditions of different hydraulic pressure outputs, and can automatically stop when the set pressure is reached, and automatically replenish pressure after pressure loss.

[0038] The device for airtightness test is of skid-mounted structure, and the equipment is semi-enclosed. The pumps, oil tanks, pipelines, filters, etc. are all installed inside the skid. The outer shell adopts an open-door structure, and the door is installed with hinges for convenient equipment maintenance. The control valves, pipelines and pressure gauges are installed above the pump body. The control valves, pressure gauges, etc. are all installed on a panel, and there are corresponding nameplates. The functions of the pressure gauges correspond to those of the valves, and the nameplates are fixed by rivets or bolt nuts. The skid is equipped with casters and lifting points for easy movement and hoisting. The casters adopt two fixed casters and two swivel casters, all with brakes. All metal structural parts of the device are made of stainless steel. The equipment is equipped with compressed air filtering and drying devices to avoid damage to pressurizing equipment, etc., and ensure the long-term normal operation of the system.

[0039] The airtightness test method for LGIM main engine components implemented by using the above device includes:

[0040] 1) Fill the fuel tank 8 with hydraulic oil and the water storage tank 10 with water; connect the compressed air inlet to an external compressed air source with a hose and input compressed air at a pressure of 7 bar; connect the nitrogen inlet to an external nitrogen cylinder with a hose and input nitrogen at a pressure of 150 bar; connect the nitrogen outlet, nitrogen return port, low-pressure supplementary oil outlet, high-pressure sealing oil outlet, high-pressure control oil outlet, low-pressure sealing oil outlet, main engine sealing oil outlet, test chamber oil return port and water outlet to the corresponding interfaces on the gas components of the main engine cylinder head with high-pressure hoses. Among them, the nitrogen outlet outputs nitrogen with a maximum pressure of 7 bar to the main engine, the low-pressure supplementary oil outlet outputs low-pressure oil with a maximum pressure of 28 bar to the main engine, the high-pressure sealing oil outlet outputs high-pressure oil with a maximum pressure of 100 bar to the main engine, the high-pressure control oil outlet outputs high-pressure oil with a maximum pressure of 400 bar to the main engine, the low-pressure sealing oil outlet outputs low-pressure oil with a maximum pressure of 30 bar to the main engine, the main engine sealing oil outlet outputs low-pressure oil with a maximum pressure of 16 bar to the main engine, and the water outlet outputs circulating water with a maximum pressure of 13 bar to the main engine.

[0041] 2) Open all the gas pressure regulating valves 12 that control each oil pump in the compressed air circuit to boost the pressure of the hydraulic oil circuit. At the same time, use an external adjustable pressure reducing valve to adjust the oil pressure of each circuit within the maximum pressure range to a predetermined target value.

[0042] 3) When the oil pressure of each circuit in the hydraulic oil circuit reaches the predetermined target, open the stop valve 23 in the nitrogen circuit. When the nitrogen pressure in the circuit rises to the process-set target value, close the stop valve 23 immediately, and the main engine starts the airtightness and functionality test of the gas block.

[0043] 4) After the test is completed, first open the stop valve 19 in the nitrogen circuit to relieve the pressure. After the nitrogen is completely depressurized, open the stop valve 15 in each hydraulic circuit to relieve the pressure, and the hydraulic oil in the hydraulic oil circuit automatically returns to the fuel tank 8.

[0044] 5) If an emergency occurs during the airtightness test, immediately open the stop valve 15 in the hydraulic oil circuit and the stop valve 19 in the nitrogen circuit to relieve the pressure of the circuit and confirm whether the safety valves 13 in the hydraulic oil circuit and 28 in the nitrogen circuit are working.

[0045] The above is only the preferred embodiment of the present invention and is not used to limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made according to the content of the application of the present invention should fall within the technical scope of the present invention.

Claims

1. An apparatus for airtightness testing of LGIM host components, which is connected to the host and provides a test medium during airtightness testing, is characterized in that: The device includes a nitrogen circuit, a hydraulic oil circuit, a compressed air circuit and a water circuit; The nitrogen circuit is used to supply nitrogen to the host, and includes a nitrogen input port, a nitrogen output port and a nitrogen return port; the nitrogen input port is connected to the nitrogen output port through a gas pressure reducing valve and a stop valve in sequence, the nitrogen output port and the nitrogen return port are respectively connected to corresponding interfaces of the host, and a safety valve is provided at the nitrogen output port; The hydraulic oil circuit is used to supply hydraulic oil to the host, and includes an oil storage tank, a low-pressure supplementary oil supply pump, a high-pressure seal oil pump, a high-pressure control oil pump, a low-pressure seal oil pump, a host seal oil pump, and a low-pressure supplementary oil output port, a high-pressure seal oil output port, a high-pressure control oil output port, a low-pressure seal oil output port, a host seal oil output port and a test chamber oil return port that are respectively connected to corresponding interfaces of the host; the inlets of the low-pressure supplementary oil supply pump, the high-pressure seal oil pump, the high-pressure control oil pump, the low-pressure seal oil pump, the host seal oil pump and the test chamber oil return port are respectively connected to the oil storage tank, and the outlets of the low-pressure supplementary oil supply pump, the high-pressure seal oil pump, the high-pressure control oil pump, the low-pressure seal oil pump and the host seal oil pump are respectively connected to the low-pressure supplementary oil output port, the high-pressure seal oil output port, the high-pressure control oil output port, the low-pressure seal oil output port and the host seal oil output port through one-way valves, and are respectively connected to the oil return pipe leading to the oil storage tank through safety valves, and this oil return pipe is respectively connected to the inlets of the low-pressure supplementary oil supply pump, the high-pressure seal oil pump, the high-pressure control oil pump, the low-pressure seal oil pump and the host seal oil pump through stop valves; The water circuit is used to supply circulating water to the host, and includes a water storage tank, a water inlet, a water return port, a water pressure pump and a water outlet; the water storage tank is respectively connected to the water inlet and the water return port, the inlet of the water pressure pump is connected to the water inlet through a one-way valve, and the outlet is connected to the water outlet through a one-way valve, and this water outlet is connected to a corresponding interface of the host, and the outlet of the water pressure pump is also connected to the water return port through a safety valve, and a stop valve is connected in parallel with this safety valve; The compressed air circuit is respectively connected to the hydraulic oil circuit and the water circuit, and is used to provide compressed air for controlling the low-pressure supplementary oil supply pump, the high-pressure seal oil pump, the high-pressure control oil pump, the low-pressure seal oil pump, the host seal oil pump and the water pressure pump, and includes a compressed air input port and a compressed air source treatment triple unit connected to this compressed air input port, and this compressed air source treatment triple unit is respectively connected to the low-pressure supplementary oil supply pump, the high-pressure seal oil pump, the high-pressure control oil pump, the low-pressure seal oil pump, the host seal oil pump and the water pressure pump through a gas stop valve and a gas pressure regulating valve in sequence.

2. The device for airtightness testing of LGIM host components according to claim 1, wherein: The oil storage tank is used to store hydraulic oil, and a permanent magnet is installed inside to adsorb iron filings in the oil.

3. The device for airtightness testing of LGIM host components according to claim 1, characterized in that: The outlets of the high-pressure seal oil pump and the high-pressure control oil pump are connected to the oil return pipe leading to the oil storage tank through a two-position three-way valve for controlling pressure reduction.

4. The device for airtightness testing of LGIM host components according to claim 1, wherein: An accumulator is connected to the outlets of the high-pressure control oil pump and the water pressure pump, and this accumulator has a voltage stabilizing and compensating function.

5. The device for airtightness testing of LGIM host components according to claim 1, wherein: Pressure gauges are provided at the inlets of the low-pressure supplementary oil supply pump, high-pressure seal oil pump, high-pressure control oil pump, low-pressure seal oil pump, main engine seal oil pump, and water pressurizing pump.

6. The device for airtightness testing of LGIM host components according to claim 1, characterized in that: The device is of a semi-closed skid-mounted structure, with a door on the outer shell, casters and lifting points installed at the lower part, and a compressed air filtration and drying device inside.

7. A method for airtightness testing of LGIM host components implemented by the device according to claim 1, characterized in that: The method includes the following steps: 1) Fill the fuel tank with hydraulic oil, fill the water storage tank with water, connect the compressed air input port to an external compressed air source, connect the nitrogen input port to an external nitrogen cylinder, and connect the nitrogen output port, nitrogen return port, low-pressure supplementary oil output port, high-pressure seal oil output port, high-pressure control oil output port, low-pressure seal oil output port, main engine seal oil output port, test chamber oil return port, and water outlet to the corresponding interfaces on the gas components of the main engine cylinder head; 2) Open all the gas pressure regulating valves in the compressed air circuit that control the oil pumps, boost the pressure in the hydraulic oil circuit, and at the same time adjust the oil pressure to a predetermined target value within the maximum pressure range; 3) When the oil pressure in the hydraulic oil circuit reaches the predetermined target, open the stop valve in the nitrogen circuit. When the nitrogen pressure rises to the process-set target value, close this stop valve, and the main engine starts an airtightness test; 4) After the test is completed, first open the stop valve in the nitrogen circuit to relieve the pressure. After the nitrogen is completely depressurized, open the stop valve in the hydraulic circuit to relieve the pressure, and the hydraulic oil flows back into the fuel tank; 5) If an emergency occurs during the airtightness test, immediately open the stop valves in the hydraulic oil circuit and the nitrogen circuit to relieve the pressure in the circuits and confirm whether the safety valves in the hydraulic oil circuit and the nitrogen circuit are working.

8. The method for airtightness testing of LGIM host components according to claim 7, characterized in that: In step 1) above, the input pressure of the compressed air input port is 7 bar, the input pressure of the nitrogen input port is 150 bar, the maximum pressure of the nitrogen output from the nitrogen output port to the main engine is 7 bar, the maximum pressure of the low-pressure supplementary oil output from the low-pressure supplementary oil output port to the main engine is 28 bar, the maximum pressure of the high-pressure seal oil output from the high-pressure seal oil output port to the main engine is 100 bar, the maximum pressure of the high-pressure control oil output from the high-pressure control oil output port to the main engine is 400 bar, the maximum pressure of the low-pressure seal oil output from the low-pressure seal oil output port to the main engine is 30 bar, the maximum pressure of the main engine seal oil output from the main engine seal oil output port to the main engine is 16 bar, and the maximum pressure of the circulating water output from the water outlet to the main engine is 13 bar.

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