Constant pressure stabilizing device for diesel engine oil supply system

Abstract

The application discloses a constant-pressure stabilizing device for a diesel engine oil supply system, and belongs to the field of diesel engine oil supply. The device is installed in series in an oil return pipeline of an electrically controlled unit pump, and is used for maintaining the pressure of the oil return pipeline constant. The device comprises a valve body, a valve core, a spring, a screw plug, a bushing and an adjusting gasket. The valve body is provided with fuel inlets and outlets and an inner cavity communicating the two. The valve core is in a cylindrical structure and is arranged in an axial sliding mode in the front part of the inner cavity. The front end of the valve core is in sealing cooperation with the conical surface of the fuel inlet. The outer cylindrical surface of the front end of the valve core is uniformly provided with first through holes communicating the inside of the valve core with the fuel outlet. The spring is arranged in the inside of the valve core and abuts against the closed end of the valve core. The screw plug is fixed in the rear part of the inner cavity. The front end of the screw plug is provided with a groove for the rear end of the spring to abut against, and a plurality of second through holes are formed in the screw plug. The bushing is used to press the screw plug to prevent loosening. The adjusting gasket is arranged between the rear end of the spring and the groove to adjust the opening pressure. The application meets the engineering target of keeping the pressure of the low-pressure oil circuit at 0.6 MPa, and is convenient to install and maintain.

Description

Technical Field

[0001] This invention relates to the field of diesel engine fuel supply technology, and in particular to a constant pressure stabilizing device for a diesel engine fuel supply system. Background Technology

[0002] When the electronically controlled unit pump is working, the oil chamber on the pump body must be kept full of clean diesel fuel and maintain a certain oil pressure to ensure that low-pressure fuel quickly fills the inner cavity of the plunger sleeve when the oil inlet on the plunger sleeve is opened, while preventing air from entering the oil passage and ensuring the normal operation of the engine.

[0003] To meet the above requirements, a constant pressure stabilizing device is usually installed in the fuel line. Its basic working principle is as follows: diesel fuel supplied by the diesel filter flows into the oil chamber through the oil inlet on the pump body. When the pressure inside the oil chamber exceeds the preset opening pressure of the device, the device opens, and the excess diesel fuel flows back to the fuel tank through the return port, thereby controlling the pressure in the oil chamber within the set range.

[0004] However, in actual operation, especially during startup and under heavy load conditions, electronically controlled unit pump diesel engines require a large fuel supply. If the low-pressure fuel circuit cannot establish pressure properly, it will lead to problems such as difficulty starting the engine, idling erratically, and instability at high speeds. At the same time, due to the limited installation space, specific interface types, and pipeline layout of the entire machine, existing constant pressure stabilization devices either have mismatched pressure regulation ranges or unsuitable structural dimensions, making it difficult to meet the design requirement of maintaining the low-pressure fuel circuit at 0.6 MPa. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a constant pressure stabilizing device for a diesel engine fuel supply system. The present invention designs a compact and reliable constant pressure stabilizing device within a limited space to meet the engineering goal of maintaining the low pressure oil circuit pressure at 0.6MPa, while taking into account the feasibility of installation and the convenience of maintenance.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A constant pressure stabilizing device for a diesel engine fuel supply system, wherein the constant pressure stabilizing device is installed in series in the return oil line of an electronically controlled unit pump to maintain a constant pressure in the return oil line; The constant pressure stabilizing device includes a valve body, a valve core, a spring, a screw plug, a bushing, and an adjusting shim; The valve body is provided with a fuel inlet, a fuel outlet, and a through cavity connecting the two. The valve core is a cylindrical structure that is closed at one end and open at the other end. It is axially slidably disposed in the front part of the inner cavity of the valve body. Its front end outer diameter is smaller than its rear end outer diameter, and its front end and the fuel inlet are sealed with a conical surface. The front end outer cylindrical surface of the valve core has multiple first through holes evenly distributed along the circumference to connect its interior with the fuel outlet. The spring is located inside the valve core, and its front end abuts against the inner wall of the closed end of the valve core; The screw plug is fixed to the rear part of the inner cavity of the valve body to seal the rear end of the inner cavity of the valve body; the front end of the screw plug is provided with a groove for the rear end of the spring to abut against, and the screw plug is provided with a plurality of second through holes; The bushing is located at the rear end of the screw plug and is used to tighten the screw plug to prevent it from loosening; The adjusting shim is located between the rear end of the spring and the inner wall of the groove, and is used to adjust the pre-compression of the spring, thereby setting the opening pressure.

[0007] A further improvement of the technical solution of the present invention is that: the inner cavity of the valve body consists of, from front to back, a first cavity for accommodating the valve core, a second cavity for the spring to pass through, and a third cavity for installing the screw plug; the connection between the first cavity and the fuel inlet is provided with a first conical surface that seals with the conical surface at the front end of the valve core.

[0008] A further improvement of the technical solution of the present invention is that: the cone angle of the first conical surface is 90°±15′, its surface roughness is not greater than Rz6.3, and the cone surface runout is not greater than 0.01mm.

[0009] A further improvement of the technical solution of the present invention is that: the front end of the valve core is provided with a second conical surface for sealing and cooperating with the conical surface of the fuel inlet; and the inner wall of the open end of the valve core is provided with a third conical surface.

[0010] A further improvement of the technical solution of the present invention is that: the cone angle of the second cone surface is 90°±15′, its surface roughness is not greater than Rz6.3, and the cone surface runout is not greater than 0.01mm.

[0011] A further improvement of the technical solution of the present invention is that: the rear end center of the screw plug is provided with a keyway, and its front end is provided with a boss.

[0012] A further improvement of the technical solution of the present invention is that the number of the first through holes is six.

[0013] A further improvement of the technical solution of the present invention is that the number of the second through holes is eight.

[0014] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows: 1. This invention installs a constant pressure stabilizing device in series in the return oil line of the electronically controlled unit pump, so that the low pressure oil line pressure is kept stable at 0.6MPa, ensuring constant fuel pressure in the pump chamber and effectively meeting the pressure and flow requirements of the diesel engine under different operating conditions.

[0015] 2. The present invention has a compact structure and small size, which can meet the limited installation space requirements of the electronically controlled unit pump diesel engine, while ensuring the pressure requirements in the pump chamber. At the same time, it can also prevent the electronically controlled unit pump from being damaged by a sudden increase in system pressure. In addition, the device is integrated into the return oil pipeline, without changing the main structure of the original fuel supply system, making installation and maintenance convenient.

[0016] 3. This invention uses a constant pressure stabilizing device to maintain a stable back pressure in the return oil pipeline, avoiding interference from return oil pressure fluctuations on the pump chamber pressure, preventing abnormal pressure fluctuations from affecting the operation of the individual pump, and improving the working stability and reliability of the oil supply system.

[0017] 4. This invention ensures that the unit pump plunger draws sufficient oil under conditions of high oil demand, such as when the engine is just starting or under heavy load, thus avoiding problems such as difficulty in starting the engine, idling surging, and high-speed instability caused by the inability of low-pressure oil circuit pressure to build up properly.

[0018] 5. This invention adjusts the spring preload by adjusting the shims, allowing for flexible setting of the opening pressure value to adapt to the pressure requirements of different models, thus exhibiting good versatility and adaptability. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a fuel flow diagram of the electronically controlled unit pump in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a constant pressure stabilizing device for a diesel engine fuel supply system provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the valve body structure in an embodiment of the present invention; Figure 4 This is a cross-sectional view of the valve core structure in an embodiment of the present invention; Figure 5 This is a schematic diagram of the overall structure of the valve core in an embodiment of the present invention; Figure 6 This is a cross-sectional view of the screw plug structure in an embodiment of the present invention; Figure 7 This is a schematic diagram of the overall structure of the screw plug in an embodiment of the present invention; Among them, 1. Electrically controlled unit pump; 2. Constant pressure stabilizing device; 21. Valve body; 211. First conical surface; 212. First chamber; 213. Second chamber; 214. Third chamber; 22. Valve core; 221. Second conical surface; 222. First through hole; 223. Third conical surface; 23. Spring; 24. Plug; 241. Second through hole; 242. Groove; 243. Keyway; 244. Boss; 25. Bushing; 26. Adjusting shim; 3. Oil return line; 4. Oil inlet line. Detailed Implementation

[0020] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims and accompanying drawings of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product or device.

[0021] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments: like Figures 1 to 7 As shown, a constant pressure stabilizing device for a diesel engine fuel supply system is provided. The constant pressure stabilizing device 2 is installed in series in the return oil line 3 of the electronically controlled unit pump 1 to maintain a constant pressure in the return oil line 3. The constant pressure stabilizing device 2 includes a valve body 21, a valve core 22, a spring 23, a screw plug 24, a bushing 25, and an adjusting shim 26. The valve body 21 has a fuel inlet, a fuel outlet, and a through-cavity connecting the two. The valve core 22 is a cylindrical structure closed at one end and open at the other, axially slidingly disposed at the front of the inner cavity of the valve body 21. Its front end outer diameter is smaller than its rear end outer diameter, and its front end and the fuel inlet are sealed with a conical surface. The outer cylindrical surface at the front end of the valve core 22 has multiple first through holes 222 evenly distributed circumferentially along its front end for connecting its interior with the fuel outlet. The spring... Spring 23 is located inside valve core 22, with its front end abutting against the inner wall of the closed end of valve core 22; plug 24 is fixed to the rear part of the inner cavity of valve body 21 and is used to seal the rear end of the inner cavity of valve body 21; the front end of plug 24 is provided with a groove 242 for the rear end of spring 23 to abut against, and multiple second through holes 241 are provided on plug 24; bushing 25 is located at the rear end of plug 24 and is used to press plug 24 to prevent loosening; adjusting shim 26 is located between the rear end of spring 23 and the inner wall of groove 242 and is used to adjust the pre-compression of spring 23, thereby setting the opening pressure.

[0024] Specifically, the fuel inlet of the constant pressure stabilizing device 2 is connected to the upstream end of the return oil pipeline 3, and the fuel outlet of the constant pressure stabilizing device 2 is connected to the downstream end of the return oil pipeline 3.

[0025] When the electronically controlled unit pump 1 is operating normally, excess fuel after injection flows into the fuel inlet of the constant pressure stabilizing device 2 via the return line 3. If the pressure in the return line 3 is lower than the set opening pressure of the constant pressure stabilizing device 2, the valve core 22 remains sealed to the fuel inlet under the elastic force of the spring 23, the return line 3 is closed, and the pressure in the oil chamber of the electronically controlled unit pump 1 is maintained. When the pressure in the return line 3 rises and exceeds the set opening pressure, the fuel pressure pushes the valve core 22 backward against the preload of the spring 23, the conical surface at the front end of the valve core 22 disengages from the fuel inlet, the return passage is opened, and excess fuel flows out through the first through hole 222 on the valve core 22 and the second through hole 241 on the plug, and flows back to the fuel tank via the return line 3. When the pressure in the return line 3 falls back below the set opening pressure, the valve core 22 resets under the elastic force of the spring 23, re-sealing the fuel inlet. This cycle repeats, achieving constant pressure control in the return line 3.

[0026] The constant pressure stabilizing device 2 has an opening pressure setting of 0.6MPa ± 0.02MPa. The required flow rate and inlet pressure are as follows: at idle speed with a low-pressure oil flow rate of 3.8L / min, the inlet pressure is 0.57MPa ± 0.02MPa; at rated speed with a low-pressure oil flow rate of 12.5L / min, the inlet pressure is 0.75MPa ± 0.05MPa. The inlet pressure is adjusted using shims 26 (circular thin sheets that match the shape of the groove 242). By replacing shims 26 with different thicknesses, the opening pressure can be precisely set, flexibly adapting to different operating conditions. A conical seal ensures no static leakage, and bushing 25 ensures that the plug 24 does not loosen under vibration, improving reliability.

[0027] Furthermore, such as Figure 3 As shown, the inner cavity of the valve body 21, from front to back, consists of a first cavity 212 for accommodating the valve core 22, a second cavity 213 for the spring 23 to pass through, and a third cavity 214 for installing the screw plug 24. The first cavity 212 has a first conical surface 211 at its connection with the fuel inlet, which seals against the conical surface at the front end of the valve core 22. The rear end of the third cavity 214 is used to insert the oil outlet pipe. The outer contour of the valve body 21 is adapted to the stepped structure of its inner cavity.

[0028] Furthermore, the cone angle of the first conical surface 211 is 90°±15′, its surface roughness is not greater than Rz6.3, and the cone surface runout is not greater than 0.01mm.

[0029] Furthermore, such as Figure 4 , Figure 5 As shown, the front end of the valve core 22 is provided with a second conical surface 221 for sealing and engaging with the conical surface of the fuel inlet; the inner wall of the open end of the valve core 22 is provided with a third conical surface 223. The arrangement of the third conical surface 223 makes the rear part of the inner cavity of the valve core 22 flare out in a funnel shape, which can effectively reduce the fuel flow resistance and ensure the smooth discharge of fuel through the first through hole 222. On the other hand, it can also prevent the spring 23 from getting stuck during operation, thereby improving the reliability of the valve core 22.

[0030] Furthermore, the cone angle of the second conical surface 221 is 90°±15′, its surface roughness is not greater than Rz6.3, and the cone surface runout is not greater than 0.01mm.

[0031] Furthermore, such as Figure 6 , Figure 7 As shown, the screw plug 24 has a slotted keyway 243 at its rear center and a boss 244 at its front end. The slotted keyway 243 is used to engage with a tool for screwing the screw plug 24 in or out, facilitating disassembly.

[0032] Furthermore, there are six first through holes 222 to ensure the flow rate of the oil.

[0033] Furthermore, the number of second through holes 241 is eight, ensuring the flow rate of the oil.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A constant pressure stabilizing device for a diesel engine fuel supply system, characterized in that, The constant pressure stabilizing device (2) is installed in series in the return oil line (3) of the electronically controlled unit pump (1) to maintain the constant pressure of the return oil line (3); The constant pressure stabilizing device (2) includes a valve body (21), a valve core (22), a spring (23), a screw plug (24), a bushing (25), and an adjusting shim (26). The valve body (21) is provided with a fuel inlet, a fuel outlet and a through cavity connecting the two; The valve core (22) is a cylindrical structure that is closed at one end and open at the other end. It is axially slidably disposed in the front part of the inner cavity of the valve body (21). Its front end outer diameter is smaller than its rear end outer diameter, and its front end and the fuel inlet are sealed with a conical surface. The front end outer cylindrical surface of the valve core (22) has a plurality of first through holes (222) evenly distributed along the circumference to connect its interior with the fuel outlet. The spring (23) is located inside the valve core (22), and its front end abuts against the inner wall of the closed end of the valve core (22); The screw plug (24) is fixed to the rear part of the inner cavity of the valve body (21) to seal the rear end of the inner cavity of the valve body (21); the front end of the screw plug (24) is provided with a groove (242) for the rear end of the spring (23) to abut; and the screw plug (24) is provided with a plurality of second through holes (241). The bushing (25) is located at the rear end of the screw plug (24) and is used to press the screw plug (24) to prevent loosening; The adjusting shim (26) is located between the rear end of the spring (23) and the inner wall of the groove (242) to adjust the pre-compression of the spring (23) and thus set the opening pressure.

2. The constant pressure stabilizing device for a diesel engine fuel supply system according to claim 1, characterized in that, The inner cavity of the valve body (21) consists of, from front to back, a first cavity (212) for accommodating the valve core (22), a second cavity (213) for the spring (23) to pass through, and a third cavity (214) for installing the screw plug (24); the connection between the first cavity (212) and the fuel inlet is provided with a first conical surface (211) that seals with the conical surface at the front end of the valve core (22).

3. The constant pressure stabilizing device for a diesel engine fuel supply system according to claim 2, characterized in that, The cone angle of the first conical surface (211) is 90°±15′, its surface roughness is not greater than Rz6.3, and the cone runout is not greater than 0.01mm.

4. The constant pressure stabilizing device for a diesel engine fuel supply system according to claim 1, characterized in that, The valve core (22) has a second conical surface (221) at its front end for sealing with the fuel inlet conical surface; the valve core (22) has a third conical surface (223) on the inner wall of its open end.

5. A constant pressure stabilizing device for a diesel engine fuel supply system according to claim 4, characterized in that, The cone angle of the second conical surface (221) is 90°±15′, its surface roughness is not greater than Rz6.3, and the cone runout is not greater than 0.01mm.

6. The constant pressure stabilizing device for a diesel engine fuel supply system according to claim 1, characterized in that, The screw plug (24) has a keyway (243) at the rear center and a boss (244) at its front end.

7. A constant pressure stabilizing device for a diesel engine fuel supply system according to claim 1, characterized in that, The number of the first through holes (222) is six.

8. A constant pressure stabilizing device for a diesel engine fuel supply system according to claim 1, characterized in that, The number of the second through holes (241) is eight.

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