Ultrahigh-pressure oil injector with top-mounted reset spring

Abstract

The invention discloses an ultrahigh-pressure oil injector with an overhead reset spring. The ultrahigh-pressure oil injector comprises an oil injector shell, a control valve screw, the reset spring, a control valve matching part and a needle valve matching part. A stepped middle hole in the middle of the fuel injector shell and a fuel nozzle seat face form a pressure storage cavity, and the control valve matching part abuts against the needle valve matching part to form an upper coupling cavity structure and is arranged in the pressure storage cavity. The control valve assembly is provided with a control valve sleeve, a rod, a cavity, an oil inlet throttling hole and an oil outlet throttling hole, the needle valve assembly comprises a needle valve sleeve and a rod, the needle valve sleeve and the rod form a closed coupling cavity, and the volume of the closed coupling cavity is smaller than or equal to 45 mm < 3 >. The reset spring is arranged in a spring chamber at the upper end of the control valve rod, and an oil inlet throttling hole is formed in the top of the spring chamber. The upper end face of the control valve rod is a plane, and the lower end face is a spherical face and forms a self-alignment adjusting structure with the plane end of the needle valve rod. The oil injector makes remarkable technical breakthrough in the aspects of sealing performance, oil injection pressure, precision, dynamic response, oil injection rate adjustment and the like, oil consumption and emission can be effectively reduced, the power per liter of an engine is improved, powerful support is provided for efficient and environment-friendly operation of the engine, the market application prospect is wide, and the technical value is great.

Description

Technical Field

[0001] This invention belongs to the field of fuel injection systems, specifically referring to injectors in common rail injection systems, and particularly to a top-mounted, high-pressure injector with a return spring designed to meet the high-efficiency combustion requirements of China VI and Euro VI emission regulations. Background Technology

[0002] As a key component of modern internal combustion engine fuel injection technology, the performance of the common rail injection system directly determines whether the engine can meet increasingly stringent emission regulations. Within the common rail injection system, the injector is one of the core components, responsible for injecting high-pressure fuel into the engine cylinders at precise timing, duration, and quantity. It plays a crucial role in fuel atomization quality, air-fuel mixture formation, and the combustion process.

[0003] However, the mainstream common rail injectors currently used in China under high emission standards have significant shortcomings in terms of technical specifications. The maximum injection pressure of existing common rail injectors is typically limited to 2000 bar, and they generally employ a structural design with static leakage. More critically, in existing common rail injectors, a low-pressure chamber is formed between the injector assembly and the control valve assembly. According to fluid mechanics principles, the volumetric leakage of the assembly gap is directly proportional to the pressure difference, directly proportional to the cube of the gap between the assemblies, and inversely proportional to the guide length. Under this structure, when the injector fails to inject fuel, a series of problems detrimental to engine performance will occur.

[0004] On the one hand, fuel in the high-pressure chamber at the injector end leaks into the low-pressure chamber through the gap in the injector assembly. Simultaneously, high-pressure fuel in the control chamber also leaks into the low-pressure chamber through the gap in the control valve assembly. This fuel leakage significantly increases engine fuel consumption because the leaked fuel fails to participate in the combustion process, directly resulting in fuel waste. Furthermore, fuel leakage increases engine carbon emissions, which is detrimental to environmental protection and makes it difficult to meet the carbon emission reduction requirements of China VI and Euro VI emission regulations.

[0005] On the other hand, high-pressure fuel leakage at the gaps between the fuel injectors can also damage the injector components. Leaking high-pressure fuel accelerates wear on parts, shortens the lifespan of the injectors, and increases engine maintenance costs.

[0006] Due to the aforementioned problems, traditional common rail injectors can only reach a maximum injection pressure of 2000 bar, making them unreliable at higher pressures. Ultra-high pressure injection technology is crucial for improving fuel atomization quality, promoting more complete combustion, reducing emissions, and enhancing fuel economy. Therefore, developing a new type of injector that can solve the leakage problem of existing common rail injectors, increase injection pressure, and operate reliably has become an urgent need to meet China VI and Euro VI emission regulations and improve engine performance. Summary of the Invention

[0007] To address the problems of existing technologies, this invention provides a top-mounted return spring ultra-high pressure fuel injector. The injector can achieve a fuel injection pressure of 2500-3000 bar, increasing the injection rate without increasing the nozzle area. The higher injection pressure and smaller orifice diameter facilitate fuel atomization and mixing, resulting in more complete combustion.

[0008] This invention is implemented as follows: a top-mounted return spring type ultra-high pressure injector includes an injector housing, a control valve screw, a return spring, a control valve assembly, and a needle valve assembly; the injector housing has a stepped central hole in the middle, which forms a pressure accumulator cavity between the central hole and the nozzle seat surface; the key feature is that the control valve assembly forms a top-mounted coupling cavity structure close to the needle valve assembly, and both are placed in the pressure accumulator cavity; the control valve assembly includes a control valve sleeve, a control valve stem, a control cavity, an inlet throttle orifice, and an outlet throttle orifice; the needle valve assembly includes a needle valve sleeve and a needle valve stem; a sealed coupling cavity is formed between the control valve assembly and the needle valve assembly, with a volume ≤45mm². 3 The reset spring is located in the spring chamber at the upper end of the control valve stem, and the top of the spring chamber has an oil inlet throttling hole in the radial direction; the upper end face of the control valve stem is flat, and the lower end face is spherical; the upper end face of the needle valve stem is flat, and it cooperates with the spherical surface to form a self-positioning adjustment structure.

[0009] More preferably, the control valve stem is a short rod structure, with a diameter greater than that of the needle valve stem, and the difference between the two diameters is ≥0.3mm; the inner diameter of the control valve sleeve is greater than that of the needle valve sleeve, and the difference between the two diameters is ≥0.3mm.

[0010] More preferably, the guide gap between the control valve sleeve and the control valve stem is ≤8μm, and the guide length is ≥9mm; the guide gap between the needle valve sleeve and the needle valve stem is ≤10μm, and the guide length is ≥8mm.

[0011] More preferably, the diameter of the oil inlet throttling hole at the top of the spring chamber is ≥φ0.4.

[0012] More preferably, the lower end of the control valve sleeve is provided with a sealing surface that seals with the needle valve sleeve, and the sealing surface has a chamfer at the junction with the small outer circle; the upper end of the needle valve sleeve is provided with a sealing surface that seals with the control valve sleeve.

[0013] More preferably, the needle valve sleeve has a two-stage central hole: the upper end is a large-diameter hole connecting the coupling cavity, which has a chamfer between it and the sealing surface; the lower end is a needle valve rod guide hole, which has a chamfer at its lower end.

[0014] More preferably, the control valve screw presses the control valve sleeve so that it fits tightly against the inner end face of the injector housing.

[0015] In a further preferred embodiment, the lower end face of the needle valve sleeve is provided with a needle valve spring, and a chamfer is provided at the junction of the lower end face and the outer circle.

[0016] More preferably, the upper end face of the control valve stem has a chamfer of ≤0.3mm.

[0017] Further preferably, the upper end face of the needle valve stem has a chamfer of ≤0.5mm between it and the outer diameter.

[0018] Technical advantages of the invention: Compared with the traditional 2000bar common rail injector, the common rail injector of the present invention achieves significant improvements in several key performance indicators and has the following outstanding technical advantages:

[0019] Superior sealing performance and energy-saving and emission-reduction advantages: Traditional 2000bar common rail injectors suffer from static leakage in the gaps between moving parts. This not only wastes fuel and increases fuel consumption, but also exacerbates carbon emissions. Furthermore, fuel leakage can cause wear on components, reducing the injector's reliability and lifespan. This patented injector innovatively employs a static leakage-free structural design, ensuring comprehensive injector sealing even under ultra-high pressure (2500bar-3000bar) operating conditions, effectively preventing fuel leakage. This improvement directly reduces fuel consumption, decreases carbon emissions, actively responds to environmental protection requirements, and significantly improves injector reliability and lifespan, reducing engine maintenance costs.

[0020] Higher injection pressure and superior injection performance: Traditional two-stage common rail injectors can only reach a maximum injection pressure of 2000 bar, while the injector of this invention can easily reach 2500-3000 bar. This significant increase in injection pressure greatly enhances the injection rate, allowing for a shorter injection time. The faster injection rate and shorter injection time contribute to more complete fuel-air mixing, resulting in more efficient combustion and thus improving engine power output and fuel economy.

[0021] Stable central accumulator chamber and precise injection control: Traditional common rail injectors typically employ a long and narrow fuel channel design. During injection, significant pressure fluctuations occur within these channels, leading to a decrease in average effective injection pressure. Furthermore, variations in injection intervals during multiple injections can easily result in differences in injection quantity, affecting engine combustion stability and performance. The injector of this invention features a large-volume central accumulator chamber. This unique design effectively reduces pressure fluctuations during injection, ensuring stable average effective injection pressure and significantly improving the accuracy of multiple injections. Precise injection control contributes to a more stable combustion process in the engine, improving the smoothness and reliability of power output.

[0022] Optimized return spring structure and rapid dynamic response: The injector of this invention incorporates a return spring structure and features a carefully optimized overall structural layout. Through this rational design, hydraulic interference is effectively eliminated, enabling the needle valve to respond quickly to control signals and achieve precise opening and closing actions. This rapid dynamic response allows the injector to operate more accurately according to the engine's fuel injection requirements, improving the timeliness and accuracy of fuel injection and further optimizing the engine's combustion process.

[0023] Innovative Coupled Cavity Structure and Flexible Injection Adjustment: The injector control section of this invention employs an innovative coupled cavity structure design. This structure enables flexible adjustment of the injection rate, allowing for adjustments based on different combustion conditions. Through this flexible adjustment, the engine can achieve lower fuel consumption, fewer emissions, and higher power output under various operating conditions, further optimizing overall engine performance and meeting the stringent requirements of modern engines for high efficiency, environmental friendliness, and energy conservation.

[0024] In summary, the common rail injector of this invention has achieved significant technological breakthroughs in sealing, injection pressure, injection accuracy, dynamic response, and injection rate regulation through a series of innovative designs, providing strong support for the efficient and environmentally friendly operation of engines, and has broad market application prospects and important technical value. Attached Figure Description

[0025] Figure 1 This is a diagram of the injector assembly of the present invention;

[0026] Figure 2 This is a magnified view of a portion of the control section;

[0027] Figure 3 This is a magnified view of the position of the control valve assembly;

[0028] Figure 4 This is a magnified view of a portion of the coupling cavity. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] Please see Figures 1 to 4A high-pressure fuel injector with a top-mounted return spring includes an injector housing 1, a control valve screw 2, a return spring 3, a control valve assembly 4, and a needle valve assembly 5. The injector housing 1 has a stepped central hole in its middle, forming a pressure accumulator chamber Q between the central hole and the nozzle seat surface. The control valve assembly 4 is positioned close to the needle valve assembly 5, forming a top-mounted coupling chamber structure, with both components housed within the pressure accumulator chamber Q. This structure offers significant technical advantages: because the components are completely arranged within the high-pressure fuel chamber Q of the injector housing 1, there is no pressure difference, eliminating static leakage between the components. Compared to traditional structures with static leakage, this avoids fuel consumption losses and accelerated wear of parts caused by high-pressure fuel leakage, effectively reducing engine fuel consumption and carbon emissions, while extending the injector's service life and lowering engine maintenance costs. Furthermore, the large volume of the pressure accumulator chamber Q helps reduce pressure loss and fluctuations during injection, improving the average effective injection pressure and the accuracy of multiple injections, thereby enhancing engine combustion efficiency and performance.

[0031] The control valve assembly 4 includes a control valve sleeve 41, a control valve stem 42, a control chamber K, an oil inlet throttle orifice 410, and an oil outlet throttle orifice 411; the needle valve assembly 5 includes a needle valve sleeve 51 and a needle valve stem 52; a sealed coupling cavity O is formed between the control valve assembly 4 and the needle valve assembly 5, with a volume ≤ 45 mm². 3 The design of this coupling cavity O brings several technical advantages. According to fluid mechanics principles, the volumetric flow rate of the coupling cavity is directly proportional to the pressure difference, directly proportional to the cube of the gap value between the coupling components, and inversely proportional to the guide length. The 9mm guide length and the guide gap between the control valve sleeve 41 and the control valve stem 42 (within 8μm) provide a stable volumetric flow for the coupling cavity O, ensuring consistent cyclic pressure in each cycle. This achieves overall fuel quantity cyclic stability, improves the accuracy and stability of the injector's injection, and facilitates more precise fuel injection control in the engine, optimizing the combustion process.

[0032] The return spring 3 is disposed in the spring chamber 420 at the upper end of the control valve stem 42. The top of the spring chamber 420 has a radially arranged fuel inlet throttling orifice 410. When the injector is stationary, the combined force of the spring and hydraulic pressure presses the control valve stem 42 against the needle valve stem 52. When the injector closes, the return spring 3 plays a crucial role. Under the action of the spring force, the control valve stem 42 moves rapidly downwards, transmitting the force to the needle valve for rapid closure, thus improving the dynamic response speed of the injector. Simultaneously, the fuel inlet throttling orifice 410 at the top of the spring chamber 420 has a diameter ≥ φ0.4, ensuring that the spring chamber 420 is filled with fuel when the control valve stem 42 reaches the top dead center position. Under the action of the spring force and hydraulic pressure, this further accelerates the closure of the needle valve, further enhancing the dynamic response performance of the injector. This allows the engine to respond to injection commands more quickly and accurately, improving engine efficiency and performance.

[0033] The upper end face 422 of the control valve stem 42 is flat, and the lower end face 424 is spherical; the upper end face 521 of the needle valve stem 52 is flat, and it cooperates with the spherical surface to form a self-aligning adjustment structure. This spherical-flat contact structure achieves self-aligning adjustment capability through a small gap, ensuring dynamic balance during the movement of the control valve stem, preventing local overload, improving the reliability and stability of the injector operation, reducing the risk of component damage due to local overload, and extending the service life of the injector.

[0034] More preferably, the control valve stem 42 is a short rod structure, with a diameter 417 > the diameter 520 of the needle valve stem 52, and the diameter difference between the two is ≥0.3mm; the inner diameter of the control valve sleeve 41 is > the inner diameter of the needle valve sleeve 51, and the diameter difference between the two is ≥0.3mm. This diameter difference design helps to optimize the fluid flow and mechanical properties inside the injector, improve the working efficiency and reliability of the injector, and enable the injector to better adapt to the working environment of ultra-high pressure injection.

[0035] More preferably, the guide clearance between the control valve sleeve 41 and the control valve rod 42 is ≤8μm, and the guide length is ≥9mm; the guide clearance between the needle valve sleeve 51 and the needle valve rod 52 is ≤10μm, and the guide length is ≥8mm. This reasonable guide clearance and guide length design ensures the stability and accuracy of the control valve rod 42 and the needle valve rod 52 during movement, reduces problems such as uneven fuel injection caused by movement deviations, improves the fuel injection quality of the injector, and facilitates more complete combustion in the engine, thus reducing emissions.

[0036] More preferably, the oil inlet throttling hole 410 provided at the top of the spring chamber 420 has a diameter ≥ φ0.4, and its positive effect on improving the dynamic response speed of the injector has been explained above.

[0037] More preferably, the lower end of the control valve sleeve 41 is provided with a sealing surface 414 that seals with the needle valve sleeve 51, and the sealing surface 414 and the small outer circle 415 are provided with a chamfer 416.

[0038] The upper end of the needle valve sleeve 51 is provided with a sealing surface 510 that seals with the control valve sleeve 41. The good sealing design ensures that the high-pressure fuel inside the injector will not leak, ensuring the stability and reliability of the injector operation, and improving the fuel economy and emission performance of the engine.

[0039] More preferably, the needle valve sleeve 51 has a two-stage central hole: the upper end is a large-diameter hole 512 connecting to the coupling cavity O, with a chamfer 513 between it and the sealing surface 510; the lower end is a needle valve rod guide hole 514, with a chamfer 515 at its lower end. This two-stage central hole structure and chamfer design effectively ensure that the needle valve rod does not jam during relative movement, improving the smoothness and reliability of the injector's operation and reducing injection failures caused by jamming.

[0040] In a further preferred embodiment, the control valve screw 2 presses against the control valve sleeve 41, making it fit tightly against the inner end face of the injector housing 1, ensuring high-pressure sealing between the two, preventing high-pressure fuel leakage, and improving the overall performance and reliability of the injector.

[0041] More preferably, the lower end face 511 of the needle valve sleeve 51 is provided with a needle valve spring 6, and the lower end face 511 is provided with a chamfer 516 at the junction with the outer circle, which helps the needle valve rod to reset and move stably, and improves the fuel injection performance of the injector.

[0042] More preferably, the upper end face 422 of the control valve stem 42 is provided with a chamfer 423 of ≤0.3mm, which reduces stress concentration and improves the strength and reliability of the control valve stem 42.

[0043] In a further preferred embodiment, a chamfer 522 of ≤0.5mm is provided between the upper end face 521 of the needle valve rod and the outer diameter 520, which also reduces stress concentration, improves the strength and reliability of the needle valve rod 52, and extends the service life of the injector.

[0044] In summary, the top-mounted return spring ultra-high pressure injector of the present invention solves the problems of leakage, slow dynamic response, and inaccurate injection of existing common rail injectors through its unique structural design. It has multiple technical effects such as improving fuel economy, reducing emissions, extending service life, and improving operational reliability and stability, and can better meet the requirements of China VI and Euro VI emission regulations for efficient combustion in engines.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A top-mounted return spring type ultra-high pressure injector, comprising an injector housing (1), a control valve screw (2), a return spring (3), a control valve assembly (4), and a needle valve assembly (5); the injector housing (1) has a stepped central hole in the middle, and a pressure accumulator (Q) is formed between the central hole and the nozzle seat surface; characterized in that: The control valve assembly (4) forms an upper coupling cavity structure close to the needle valve assembly (5), and both are placed in the accumulator cavity (Q); the control valve assembly (4) includes a control valve sleeve (41), a control valve stem (42), a control cavity (K), an oil inlet throttle orifice (410), and an oil outlet throttle orifice (411); the needle valve assembly (5) includes a needle valve sleeve (51) and a needle valve stem (52); the control valve assembly (4) and the needle valve assembly (5) form a closed coupling cavity (O) with a volume ≤ 45 mm. 3 The reset spring (3) is located in the spring chamber (420) at the upper end of the control valve stem (42), and the top of the spring chamber (420) is provided with an oil inlet throttling hole (410) in the radial direction; the upper end face (422) of the control valve stem (42) is a plane, and the lower end face (424) is a spherical surface; the upper end face (521) of the needle valve stem (52) is a plane, which cooperates with the spherical surface to form a self-positioning adjustment structure.

2. The injector according to claim 1, characterized in that: The control valve stem (42) is a short rod structure, and its diameter (417) is greater than the diameter (520) of the needle valve stem (52), with a diameter difference of ≥0.3mm; the inner diameter of the control valve sleeve (41) is greater than the inner diameter of the needle valve sleeve (51), with a diameter difference of ≥0.3mm.

3. The injector according to claim 1, characterized in that: The guide gap between the control valve sleeve (41) and the control valve stem (42) is ≤8μm, and the guide length is ≥9mm; the guide gap between the needle valve sleeve (51) and the needle valve stem (52) is ≤10μm, and the guide length is ≥8mm.

4. The injector according to claim 1, characterized in that: The oil inlet throttling hole (410) provided at the top of the spring chamber (420) has a diameter ≥ φ0.

4.

5. The injector according to claim 1, characterized in that: The lower end of the control valve sleeve (41) is provided with a sealing surface (414) that seals with the needle valve sleeve (51), and a chamfer (416) is provided at the junction of the sealing surface (414) and the small outer circle (415); the upper end of the needle valve sleeve (51) is provided with a sealing surface (510) that seals with the control valve sleeve (41).

6. The injector according to claim 1, characterized in that: The needle valve sleeve (51) has two-stage central holes: the upper end is a large-diameter hole (512) that connects to the coupling cavity (O), and a chamfer (513) is provided between it and the sealing surface (510); the lower end is a needle valve rod guide hole (514), and a chamfer (515) is provided at its lower end.

7. The injector according to claim 1, characterized in that: The control valve screw (2) presses the control valve sleeve (41) so that it fits tightly against the inner end face of the injector housing (1).

8. The injector according to claim 1, characterized in that: The lower end face (511) of the needle valve sleeve (51) is provided with a needle valve spring (6), and a chamfer (516) is provided at the junction of the lower end face (511) and the outer circle.

9. The injector according to claim 1, characterized in that: The upper end face (422) of the control valve stem (42) is provided with a chamfer (423) of ≤0.3mm.

10. The injector according to claim 1, characterized in that: A chamfer (522) of ≤0.5mm is provided between the upper end face (521) of the needle valve stem and the outer diameter (520).

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