A pneumatic injection test device for adjusting the needle valve lift

Abstract

The present invention provides an injection test device for pneumatically adjusting the needle valve lift, comprising: an injection box component, wherein the top of the injection observation box included in the injection box is provided with a nozzle and is fixedly connected with a valve body component; the valve body component comprises: a valve body, which is fixedly connected with the injection observation box; a needle valve, which is arranged in the valve body; a joint, one end of which is nested and arranged at the top of the valve body, and the other end is connected with a compression component; a connecting rod is arranged in the inner cavity of the joint; the compression component comprises: a cylinder, the bottom of which is fixedly connected with the joint; a drive cover, which is fixedly arranged at the top of the cylinder; a piston, which is arranged in the inner cavity of the cylinder; a pneumatic control component, wherein the air intake assembly and the exhaust assembly included in the pneumatic control component are arranged at the bottom of the cylinder, and the piston is controlled to move in the cylinder, driving the connection rod and the needle valve to rise or fall; a needle valve limiter component, which is arranged at the top of the drive cover, and is used to limit the displacement of the piston. The present invention has the advantages of adjustable needle valve lift, energy saving and environmental protection.

Description

Technical Field

[0001] The invention belongs to the field of high-pressure spray devices, and in particular relates to a spray test device for pneumatically regulating the lift of a needle valve. Background Art

[0002] As an important component of the internal combustion engine, the diesel engine injector has a significant impact on the diesel engine's emissions and fuel consumption. Among them, the needle valve in the injector has a significant impact on the fuel injection and atomization process. Therefore, controlling the needle valve lift to conduct injection tests is of great significance to fuel atomization. The existing injection test device only controls the maximum lift of the needle valve, and the needle valve lift is inconvenient to adjust. It is difficult to carry out research on the effect of the needle valve lift on fuel atomization, as well as further develop control strategies for the needle valve stroke on fuel spray. Considering the high-pressure characteristics of the fuel injection pressure and safe operation, it is urgent to propose a safe and reliable injection test device that can adjust the needle valve lift. Summary of the invention

[0003] In order to realize the opening and closing, rapid lifting and stroke setting of the needle valve in the injection test, the present invention proposes an injection test device with pneumatic adjustment of the needle valve lift, which controls the rapid opening and closing of two solenoid valves through a computer system to realize continuous intake and exhaust of compressed gas, so that the piston and needle valve are lifted and lowered to realize the opening or closing of the nozzle, thereby realizing the fuel spray state under different needle valve specific lifts. The needle valve lift is limited by the fine adjustment rod, and different needle valve lifts lead to different fuel flow rates in the nozzle, so the fuel atomization conditions of different fuel flow rates can be observed.

[0004] To achieve the above-mentioned purpose, the present invention provides an injection test device for pneumatically adjusting the needle valve lift, which comprises: an injection box component, wherein the top of the injection observation box included in the injection box is provided with a nozzle and is fixedly connected to a valve body component; the valve body component comprises: a valve body, which is fixedly connected to the top of the injection observation box and the bottom is connected to the nozzle; a needle valve, which is arranged in the valve body, the top end of which is aligned with the nozzle and can move vertically along the inner wall of the valve body; a fuel inlet, which is opened on one side of the valve body and is used to receive the input of high-pressure fuel; a connector, one end of which is nested in the top of the valve body and the other end of which is connected to a compression component; the connector A connecting rod is arranged in the inner cavity; the compression component includes: a cylinder body, the bottom of which is fixedly connected to the joint; a drive cover, which is fixedly arranged on the top of the cylinder body and forms a closed inner cavity with the cylinder body; a piston, which is arranged in the inner cavity of the cylinder body and the bottom is fixedly connected to the connecting rod; the end of the connecting rod not connected to the piston is fixedly connected to the tail end of the needle valve; a pneumatic control component, the air intake assembly and the exhaust assembly included in it are arranged at the bottom of the cylinder body, control the movement of the piston in the cylinder body, and then drive the connecting rod and the needle valve to rise or fall; a needle valve limiting component, which is arranged on the top of the drive cover and is used to limit the displacement of the piston.

[0005] Among them, the fuel injection tank component also includes: a base, which is fixedly installed at the bottom of the fuel injection observation box and is used to support the entire injection test device; a visual observation window, which is opened on the side wall of the fuel injection observation box and can observe the state of fuel ejected from the nozzle; a flange, which is fixedly arranged on the top of the fuel injection observation box and realizes the sealing between the fuel injection observation box and the flange through a first sealing ring; the flange is fixedly connected to the valve body through a plurality of first fixing parts; the nozzle is nested in the center of the flange, and a sealing packing is arranged between the nozzle and the valve body to prevent fuel leakage; an oil drain joint, which is connected to the bottom wall of the fuel injection observation box through a second sealing ring and is used to recover the fuel sprayed by the injection test.

[0006] Among them, the intake component includes: an intake pipe, whose input end is connected to the compressed gas tank, and the output end is connected to the bottom of the cylinder body; a first solenoid valve, which is arranged on the intake pipe to control the conduction or closing of the intake pipe; the exhaust component corresponding to the intake component includes: an exhaust pipe, whose input end is connected to the bottom of the cylinder body, and the output end is suspended; a second solenoid valve, which is arranged on the exhaust pipe to control the conduction or closing of the exhaust pipe.

[0007] Preferably, the driving cover is fixedly arranged on the top of the cylinder body through a plurality of second fixing members; a non-contact displacement sensor is also arranged at the bottom of the driving cover to obtain real-time displacement data of the piston and the needle valve.

[0008] Among them, the needle valve limiting component includes: a fine-tuning screw, which is arranged on the top of the driving cover, and the bottom of the fine-tuning screw penetrates the driving cover and extends into the cylinder body; a spring, which is arranged inside the cylinder body, one end of which is fixedly connected to the bottom of the fine-tuning screw, and the other end of which is fixedly connected to the top of the piston; the preload force of the spring is changed by adjusting the fine-tuning screw; a fine-tuning rod, which is penetrated and arranged on the top of the driving cover through a third fixing member, and the maximum displacement of the piston rise can be adjusted and limited by adjusting the length of the lower end of the fine-tuning rod extending into the cylinder body.

[0009] Among them, when the fine-tuning screw is tightened downward, the preload force of the spring increases, the pressure applied to the piston increases, and the speed at which the piston drives the needle valve to rise decreases; when the fine-tuning screw is loosened upward, the preload force of the spring decreases, the pressure applied to the piston decreases, and the speed at which the piston drives the needle valve to rise increases.

[0010] Preferably, a third sealing ring is also sleeved on the piston, and the third sealing ring is in close contact with the inner wall of the cylinder body, and is used to seal the compressed gas in the cylinder body to prevent the compressed gas from escaping.

[0011] Preferably, a sealing assembly for compressing the needle valve is provided between the lower end of the joint and the valve body to effectively prevent fuel leakage; the sealing assembly comprises: a thrust washer, a sealing packing and a down-pressure pad; the thrust washer is in contact with the lower end of the joint, the sealing packing is located below the thrust washer, and the down-pressure pad is located below the sealing packing and in contact with the valve body.

[0012] The fuel inlet is equipped with a matching high-pressure fuel supply system, and a high-pressure fuel pump included in the high-pressure fuel supply system is controlled to supply fuel to the fuel inlet.

[0013] Among them, the first solenoid valve, the second solenoid valve, the high-pressure fuel supply system and the non-contact displacement sensor are all connected to the computer control system through the circuit; when the injection test device performs fuel injection, the computer control system controls the first solenoid valve to open and the second solenoid valve to close at the same time, and the compressed gas enters the cavity formed by the piston and the cylinder through the intake pipe to move and do work, and the compression spring pushes the piston to lift, and the piston drives the connecting rod and the needle valve to move upward until the top of the piston contacts the bottom of the fine-adjustment rod, the channel between the nozzle and the fuel inlet is connected, and the high-pressure fuel is sprayed from the nozzle's spray hole into the injection observation box; when the fuel injection test is completed, the computer control system controls the first solenoid valve to close and the second solenoid valve to open at the same time, the compressed gas in the cylinder is discharged through the exhaust pipe, the piston is reset under the action of the spring, driving the connecting rod and the needle valve to descend and block the nozzle's spray hole, the channel between the fuel inlet and the nozzle is blocked, and the high-pressure fuel injection is stopped.

[0014] In summary, compared with the prior art, the injection test device for pneumatically adjusting the needle valve lift provided by the present invention has the following beneficial effects:

[0015] 1. The opening and closing frequency of the two solenoid valves is controlled according to the set needle valve lifting speed and closing speed, and the opening and closing time of the two solenoid valves is controlled according to the needle valve opening time. The computer controls the intake and exhaust of the solenoid valve, controls the continuous reciprocating movement of the piston and the needle valve, and realizes different movement speeds of the needle valve. The displacement sensor feeds back the real-time lift of the piston and the needle valve to the computer in real time through the different needle valve lift values ​​adjusted by the micro-adjustment rod, and then the injection amount can be adjusted;

[0016] 2. By manually adjusting the micro-adjustment lever, different needle valve lifts can be obtained. Different needle valve lifts result in different flow cross-sectional areas of the fuel in the nozzle and different fuel flow rates, so the fuel atomization conditions of different fuel flow rates can be observed.

[0017] 3. According to the test needs, the test personnel can operate the computer to control the opening and closing of the solenoid valve at a specific needle valve lift value to achieve multiple groups of injection tests at different needle valve speeds, record and save. The test personnel can observe the test completion status according to the control computer, adjust the micro-adjustment lever again, and conduct multiple groups of injection tests with different needle valve lift values.

[0018] 4. Test personnel can use a high-speed camera to observe the fuel injection and atomization conditions through the injection tank visualization window.

[0019] 5. The compressed gas used in this device is pollution-free, energy-saving and environmentally friendly. It can use various types of fuel and can be recycled. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of the injection test device for pneumatically adjusting the needle valve lift of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the attached embodiment of the present invention Figure 1 , the technical solutions, structural features, objectives achieved and effects in the embodiments of the present invention are described in detail.

[0022] It should be noted that the drawings are in a very simplified form and use non-precise proportions. They are only used to conveniently and clearly assist in explaining the embodiments of the present invention, and are not used to limit the conditions for the implementation of the present invention. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present invention.

[0023] It should be noted that, in the present invention, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only the elements explicitly listed, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0024] The present invention provides a pneumatic injection test device for adjusting the needle valve lift. Figure 1As shown, the injection test device includes: a fuel injection box component, which includes a fuel injection observation box 2 with a nozzle 5 on the top and a valve body component fixedly connected thereto; the valve body component includes: a valve body 10, which is fixedly connected to the top of the fuel injection observation box 2 and communicated with the nozzle 5 at the bottom; a needle valve 9, which is arranged in the valve body 10, with the top end aligned with the nozzle 5 and can move vertically along the inner wall of the valve body 10; a fuel inlet 8, which is opened on one side of the valve body 10 for receiving the input of high-pressure fuel; a connector 26, one end of which is nested in the top of the valve body 10 and the other end of which is connected to a compression component; a connecting rod 23 is arranged in the inner cavity of the connector 26; the compression component includes: a cylinder body 13, the bottom of which is fixedly connected to the connector 26; a drive cover 16, which is fixedly arranged on the top of the cylinder body 13 to form a closed inner cavity with the cylinder body 13; a piston 14, which is arranged in the inner cavity of the cylinder body 13 and the bottom is fixedly connected to the connecting rod 23; the connecting rod 23 is not One end connected to the piston 14 is fixedly connected to the tail end of the needle valve 9; the pneumatic control component, which includes an intake assembly and an exhaust assembly, is arranged at the bottom of the cylinder body 13 to control the movement of the piston 14 in the cylinder body 13, thereby driving the connecting rod 23 and the needle valve 9 to rise or fall; the needle valve limiting component is arranged at the top of the driving cover 16 to limit the displacement of the piston 14; wherein, when the intake assembly delivers compressed gas to the cylinder body 13, the piston 14 in the cylinder body 13 is thrust by the compressed gas, driving the connecting rod 23 and the needle valve 9 to rise, the channel between the nozzle 5 and the fuel inlet 8 is connected, and the nozzle 5 sprays fuel into the injection observation box 2; when the exhaust assembly discharges the compressed gas in the cylinder body 13, the piston 14 is pressed by the needle valve limiting component, pushing the connecting rod 23 and the needle valve 9 down, the needle valve 9 blocks the nozzle 5, the channel between the fuel inlet 8 and the nozzle 5 is blocked, and the nozzle 5 stops spraying fuel into the injection observation box 2.

[0025] Among them, Figure 1 As shown, the tail end cylinder connecting the needle valve 9 and the connecting rod 23 matches the inner cavity diameter of the valve body 10 , and the top tip matches the shape of the nozzle 5 , and the top tip can be inserted into the nozzle 5 .

[0026] Among them, Figure 1As shown, the fuel injection tank component also includes: a base 1, which is fixedly mounted on the bottom of the fuel injection observation box 2 and is used to support the entire injection test device; a visual observation window 3, which is opened on the side wall of the fuel injection observation box 2, and can observe the state of fuel ejected from the nozzle 5; a flange 4, which is fixedly arranged on the top of the fuel injection observation box 2, and the sealing between the fuel injection observation box 2 and the flange 4 is achieved through the first sealing ring 7; the flange 4 is fixedly connected to the valve body 10 through a plurality of first fixing members 30 (in this embodiment, 4 bolts are used as the first fixing members 30 to achieve the connection between the flange 4 and the valve body 10); the nozzle 5 is nested in the center of the flange 4, and a sealing packing 6 is provided between the nozzle 5 and the valve body 10 to prevent fuel leakage; an oil drain joint 31, which is connected to the bottom wall of the fuel injection observation box 2 through a second sealing ring 32, and is used to recover the fuel ejected in the injection test, so that the fuel ejected from the nozzle 5 can be collected again for recycling; in this embodiment, a rectangular sealing ring is used as the second sealing ring 32.

[0027] Furthermore, a sealing assembly for compressing the needle valve 9 is provided between the lower end of the connector 26 and the valve body 10 to prevent high-pressure fuel from entering the compression component; Figure 1 As shown, the sealing assembly includes: a thrust washer 27, a sealing packing 28 and a pressure pad 29; the thrust washer 27 is in contact with the lower end of the joint 26, the sealing packing 28 is located below the thrust washer 27, and the pressure pad 29 is located below the sealing packing 28 and in contact with the valve body 10. The above-mentioned multi-layer sealing setting can effectively prevent fuel leakage.

[0028] Among them, Figure 1 As shown, the intake assembly includes: an intake pipe 12, whose input end is connected to the compressed gas tank, and whose output end is connected to the bottom of the cylinder 13; a first solenoid valve 11, which is arranged on the intake pipe 12, and controls the conduction or closing of the intake pipe 12; the exhaust assembly includes: an exhaust pipe 25, whose input end is connected to the bottom of the cylinder 13, and whose output end is suspended, that is, the compressed gas discharged from the cylinder 13 is directly discharged into the air; a second solenoid valve 24, which is arranged on the exhaust pipe 25, and controls the conduction or closing of the exhaust pipe.

[0029] Among them, Figure 1 As shown, the drive cover 16 is fixed to the top of the cylinder body 13 by a plurality of second fixing members 21. The second fixing members 21 in this embodiment are four hexagon socket bolts. A non-contact displacement sensor 22 is also provided at the bottom of the drive cover 16, that is, the non-contact displacement sensor 22 is located in the inner cavity of the cylinder body 13 to obtain real-time displacement data of the piston 14 and the needle valve 9.

[0030] Among them, Figure 1As shown, the needle valve limiting component includes: a fine-tuning screw 19, which is arranged on the top of the driving cover 16, and the bottom of the fine-tuning screw 19 penetrates the driving cover 16 and extends into the cylinder body 13; a spring 20, which is arranged in the cylinder body 13, one end of which is fixedly connected to the bottom of the fine-tuning screw 19, and the other end of which is fixedly connected to the top of the piston 14; by adjusting the fine-tuning screw 19, the pre-tightening force of the spring 20 is changed. Specifically, when the fine-tuning screw 19 is tightened downward, the pre-tightening force of the spring 20 increases, the pressure applied to the piston 14 increases, and the lifting speed of the needle valve 9 decreases. On the contrary, when the fine-tuning screw 19 is loosened upward, the spring 20 The preload force is reduced, the pressure applied to the piston 14 is reduced, and the lifting speed of the needle valve 9 is increased; wherein, the minimum preload force is 0, that is, the spring 20 is neither compressed nor stretched; the maximum preload force is equal to the elastic limit of the spring 20; the fine-adjustment rod 18 is penetrated through the top of the drive cover 16 through the third fixing member 17 (the present embodiment adopts a connecting nut as the third fixing member 17), and the length of the lower end of the fine-adjustment rod 18 extending into the cylinder body 13 can be used to limit the maximum displacement of the piston 14 and the needle valve 9; wherein, the fine-adjustment rod 18 is modified from a spiral positioner, and can measure and fine-tune the lift of the needle valve 9.

[0031] Furthermore, a third sealing ring 15 is sleeved on the piston 14 , and the third sealing ring 15 is in close contact with the inner wall of the cylinder body 13 , and is used to seal the compressed gas in the cylinder body 13 to prevent the compressed gas from escaping; wherein, an O-ring is used as the third sealing ring 15 in this embodiment.

[0032] In order to provide high-pressure fuel, the device is installed with a matching high-pressure fuel supply system to control the fuel supply of a high-pressure fuel pump included in the high-pressure fuel supply system; the fuel inlet 8 is connected to the high-pressure fuel pump through a pipeline, and the high-pressure fuel provided by the high-pressure fuel pump enters the oil inlet channel through the fuel inlet 8, flows into the inside of the nozzle 5, and then is sprayed from the spray hole of the nozzle 5 into the inside of the fuel injection observation box 2.

[0033] In order to realize the automation of the injection test device, the device is also equipped with a matching computer control system, which is respectively connected to the first solenoid valve 11, the second solenoid valve 24, the high-pressure fuel supply system and the non-contact displacement sensor 22 through circuits to form a closed-loop control system; specifically, when the injection test device performs fuel injection, the computer control system controls the first solenoid valve 11 to open and the second solenoid valve 24 to close, and the compressed gas enters the cavity formed by the piston 14 and the cylinder body 13 through the intake pipe 12 to move and do work, resisting the preload force of the spring 20, thereby pushing the piston 14 to lift. Due to the different pressures of the compressed gas, the lifting speed of the needle valve 9 is also different; the piston 14 drives the connecting rod 23 and the needle valve 9 to move upward until the top of the piston 14 contacts the bottom of the fine-adjustment rod 18, and stops moving upward due to the limit of the fine-adjustment rod 18. At this time, the channel between the nozzle 5 and the fuel inlet 8 is connected and opened, and the high-pressure fuel is sprayed from the spray hole of the nozzle 5. When the fuel injection test is completed, the computer control system controls the first solenoid valve 11 to close, and controls the second solenoid valve 24 to open. The air intake pipe 12 for inputting compressed gas is cut off, and the internal compressed gas is discharged through the exhaust pipe 25. The piston 14 is quickly reset under the action of the spring 20, so that the connecting rod 23 drives the needle valve 9 to descend and block the spray hole of the nozzle 5. The channel between the fuel inlet 8 and the nozzle 5 is blocked, thereby stopping the high-pressure fuel injection; the whole process realizes the automatic opening and closing of the nozzle 5, so that the high-pressure fuel is sprayed into the injection observation box 2 through the nozzle 5; at the same time, the non-contact displacement sensor 22 records the displacement value of the piston 14 in the entire injection test in real time, and feeds it back to the computer control system.

[0034] It should be noted that before the test personnel use the injection test device with pneumatic adjustment of needle valve lift to conduct the high-pressure fuel injection test, they need to use the micro-adjustment rod 18 to adjust it to the specific needle valve lift required by the test; under this needle valve lift, the computer control system controls the opening of the solenoid valve, and the fuel injection is atomized, and the high-speed camera synchronously shoots through the visual observation window 3, so as to observe the fuel spray situation; the test personnel can adjust the position of the micro-adjustment rod 18 multiple times to observe the spray situation under different needle valve lifts.

[0035] Among them, different needle valve lifts can be obtained by manually adjusting the fine adjustment rod 18; different needle valve lifts lead to different flow cross-sectional areas of the fuel in the nozzle 5 and different fuel flow rates, so the fuel atomization conditions of different fuel flow rates can be observed.

[0036] Furthermore, the opening and closing frequencies of the two solenoid valves are controlled according to the set needle valve lifting speed and closing speed, and the opening and closing time of the two solenoid valves are controlled according to the needle valve opening time. The intake and exhaust of the two solenoid valves are controlled by a computer control system, and the control piston 14 drives the connecting rod 23 and the needle valve 9 to continuously reciprocate and realize different movement speeds of the needle valve 9.

[0037] Among them, the test personnel can operate the computer control system to control the opening and closing frequency of the solenoid valve under a specific needle valve lift according to the test needs, so as to realize multiple groups of injection tests at different needle valve speeds, record and save. The test personnel can observe the test completion status according to the control computer, adjust the fine adjustment rod 18 again, and conduct multiple groups of injection tests with different needle valve lift values.

[0038] In summary, compared with the existing injection test device, the injection test device with pneumatically adjustable needle valve lift provided by the present invention has the advantages of adjustable needle valve lift, controllable injection frequency, energy saving and environmental protection.

[0039] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A pneumatic injection test device for adjusting the needle valve lift, characterized in that: include: A fuel injection box component, comprising a fuel injection observation box (2) having a nozzle (5) disposed on the top and a valve body component fixedly connected thereto; The valve body component comprises: a valve body (10) fixedly connected to the top of the fuel injection observation box (2) and connected to the nozzle (5) at the bottom; a needle valve (9) arranged in the valve body (10), with the top end aligned with the nozzle (5) and movable vertically along the inner wall of the valve body (10); a fuel inlet (8) opened on one side of the valve body (10) for receiving input of high-pressure fuel; a connector (26) with one end nested in the top of the valve body (10) and the other end connected to a compression component; a connecting rod (23) is arranged in the inner cavity of the connector (26); The compression component comprises: a cylinder body (13), the bottom of which is fixedly connected to a joint (26); a drive cover (16), which is fixedly arranged on the top of the cylinder body (13) and forms a closed inner cavity with the cylinder body (13); a piston (14), which is arranged in the inner cavity of the cylinder body (13) and the bottom of which is fixedly connected to a connecting rod (23); the end of the connecting rod (23) not connected to the piston (14) is fixedly connected to the tail end of the needle valve (9); A pneumatic control component, which includes an air intake assembly and an exhaust assembly, which are arranged at the bottom of the cylinder (13) to control the movement of the piston (14) in the cylinder (13), thereby driving the connection rod (23) and the needle valve (9) to rise or fall; A needle valve limiting component, which is arranged on the top of the driving cover (16) and is used to limit the displacement of the piston (14); Wherein, the air intake assembly comprises: An air inlet pipe (12), the input end of which is connected to the compressed gas tank, and the output end of which is connected to the bottom of the cylinder body (13); A first solenoid valve (11), which is arranged on the air intake pipe (12) and controls the opening or closing of the air intake pipe (12); The exhaust assembly corresponding to the air intake assembly includes: An exhaust pipe (25), the input end of which is connected to the bottom of the cylinder body (13) and the output end of which is suspended; A second solenoid valve (24), which is arranged on the exhaust pipe (25) and controls the opening or closing of the exhaust pipe; The needle valve limiting component comprises: A fine-tuning screw (19) is arranged on the top of the driving cover (16), and the bottom of the fine-tuning screw (19) penetrates the driving cover (16) and extends into the cylinder body (13); The spring (20) is arranged inside the cylinder body (13), one end of which is fixedly connected to the bottom of the fine-tuning screw (19), and the other end of which is fixedly connected to the top of the piston (14); the preload force of the spring (20) can be changed by adjusting the fine-tuning screw (19).

2. The injection test device for pneumatically adjusting the needle valve lift as claimed in claim 1, characterized in that: The fuel injection box component also includes: A base (1) fixedly mounted on the bottom of the fuel injection observation box (2) and used to support the entire injection test device; A visual observation window (3) is provided on the side wall of the fuel injection observation box (2) and is used to observe the state of fuel being ejected from the nozzle (5); A flange (4) is fixedly arranged on the top of the oil injection observation box (2), and a first sealing ring (7) is used to achieve sealing between the oil injection observation box (2) and the flange (4); The flange (4) is fixedly connected to the valve body (10) via a plurality of first fixing members (30); The nozzle (5) is nested in the center of the flange (4), and a sealing packing (6) is arranged between the nozzle and the valve body (10) to prevent fuel leakage; The oil drain connector (31) is connected to the bottom wall of the oil injection observation box (2) via a second sealing ring (32) and is used to recover the oil sprayed during the injection test.

3. The injection test device for pneumatically adjusting needle valve lift according to claim 1, characterized in that: The driving cover (16) is fixedly arranged on the top of the cylinder body (13) via a plurality of second fixing members (21); a non-contact displacement sensor (22) is also arranged at the bottom of the driving cover (16) to obtain real-time displacement data of the piston (14) and the needle valve (9).

4. The injection test device for pneumatically adjusting needle valve lift as claimed in claim 1, characterized in that: The needle valve limiting component also includes: A fine adjustment rod (18) is provided on the top of the driving cover (16) through a third fixing member (17). By adjusting the length of the lower end of the fine adjustment rod (18) extending into the cylinder body (13), the maximum displacement of the piston (14) can be adjusted and limited.

5. The injection test device for pneumatically adjusting the needle valve lift as claimed in claim 4, characterized in that: When the fine-tuning screw (19) is tightened downward, the preload force of the spring (20) increases, the pressure applied to the piston (14) increases, and the speed at which the piston (14) drives the needle valve (9) to rise decreases; when the fine-tuning screw (19) is loosened upward, the preload force of the spring (20) decreases, the pressure applied to the piston (14) decreases, and the speed at which the piston (14) drives the needle valve (9) to rise increases.

6. The injection test device for pneumatically adjusting the needle valve lift as claimed in claim 1, characterized in that: The piston (14) is also sleeved with a third sealing ring (15), which is in close contact with the inner wall of the cylinder (13) and is used to seal the compressed gas in the cylinder (13) to prevent the compressed gas from escaping.

7. The injection test device for pneumatically adjusting needle valve lift as claimed in claim 1, characterized in that: A sealing assembly for compressing the needle valve (9) is arranged between the lower end of the joint (26) and the valve body (10), thereby effectively preventing fuel leakage; the sealing assembly comprises: a thrust washer (27), a sealing packing (28) and a lower pressure pad (29); the thrust washer (27) is in contact with the lower end of the joint (26), the sealing packing (28) is located below the thrust washer (27), and the lower pressure pad (29) is located below the sealing packing (28) and in contact with the valve body (10).

8. The injection test device for pneumatically adjusting the needle valve lift as claimed in claim 3, characterized in that: The fuel inlet (8) is equipped with a matching high-pressure fuel supply system, and a high-pressure fuel pump included in the high-pressure fuel supply system is controlled to supply fuel to the fuel inlet (8).

9. The injection test device for pneumatically adjusting the needle valve lift as claimed in claim 8, characterized in that: The first solenoid valve (11), the second solenoid valve (24), the high-pressure fuel supply system and the non-contact displacement sensor (22) are all connected to the computer control system via a circuit; When the injection test device performs fuel injection, the computer control system controls the first solenoid valve (11) to open and the second solenoid valve (24) to close, and the compressed gas enters the cavity formed by the piston (14) and the cylinder (13) through the intake pipe (12) to move and perform work, and the compression spring (20) pushes the piston (14) to rise, and the piston (14) drives the connecting rod (23) and the needle valve (9) to move upward until the top of the piston (14) contacts the bottom of the fine adjustment rod (18), and the channel between the nozzle (5) and the fuel inlet (8) is connected, and the high-pressure fuel is sprayed from the spray hole of the nozzle (5) into the fuel injection observation box (2); When the fuel injection test is completed, the computer control system controls the first solenoid valve (11) to close and the second solenoid valve (24) to open, the compressed gas in the cylinder (13) is discharged through the exhaust pipe (25), the piston (14) is reset under the action of the spring (20), driving the connecting rod (23) and the needle valve (9) to descend and block the spray hole of the nozzle (5), the passage between the fuel inlet (8) and the nozzle (5) is blocked, and the high-pressure fuel injection is stopped.

Images