Flexible integrated needle valve with throttling structure

Abstract

The invention belongs to the technical field of common rail oil sprayers, and particularly discloses a flexible integrated needle valve with a throttling structure, which comprises a valve head, a valve tail and a middle section connecting the valve head and the valve tail, the middle section is a connecting rod with elastic deformation capacity, and a plurality of throttling sections are arranged on the outer side of the valve tail along the circumference at intervals. The surface of the end, close to the connecting rod, of the throttling section is provided with throttling tables, and the throttling tables are located on the same circle center circumference. Through the connecting rod and the throttling table, in the transient process that the needle valve is started or closed, the needle valve stably controls injection of fuel oil, and the flow is stable.

Description

Technical Field

[0001] This invention belongs to the field of common rail injector technology, specifically relating to a flexible integrated needle valve with a throttling structure. Background Technology

[0002] High-pressure common rail fuel injection systems can achieve flexible control over diesel engine injection timing, injection pulse width, injection rate, and injection frequency. They are widely recognized as the most advanced fuel injection technology and one of the main means to improve diesel engine economy, optimize combustion process, and reduce harmful emissions.

[0003] The high-pressure common rail system is a complex system involving electro-magnetic-mechanical-hydraulic coupling. Studies have shown that pressure fluctuations occur internally during fuel injection, leading to instability in the needle valve's movement characteristics and injection pressure. Especially during the transient process of needle valve opening or closing, the actual injection quantity may differ from the theoretically controlled injection quantity, which deteriorates the diesel engine's operating condition, specifically as follows: 1. When the needle valve moves axially within the needle valve body cavity, it will be subjected to hydraulic or mechanical impact, causing the needle valve to be unable to stably control the fuel injection process.

[0004] 2. When the needle valve is activated, high-pressure fuel flows through the needle valve at an extremely high speed, resulting in an instantaneous opening state; while when it is closed, the flow is released rapidly and the pressure decays quickly, causing the flow opening or closing process to be unstable. Summary of the Invention

[0005] The purpose of this invention is to provide a flexible integrated needle valve with a throttling structure, which stably controls fuel injection and ensures a stable flow rate during the transient process of needle valve activation or closure.

[0006] The objective of this invention is achieved through the following technical solution: a flexible integrated needle valve with a throttling structure is provided, comprising: a valve head, a valve tail, and an intermediate section connecting the valve head and the valve tail. The intermediate section is a connecting rod with elastic deformation capability. Several throttling sections are spaced apart along the outer circumference of the valve tail. A throttling platform is provided on the surface of one end of the throttling section near the connecting rod, and each throttling platform is on the same circumference.

[0007] Preferably, the connecting rod is welded to the valve head and valve tail respectively.

[0008] Preferably, the connecting rod is made of 16CrMn.

[0009] Preferably, the ratio of the outer diameter to the length of the connecting rod is 1:35 to 1:25.

[0010] Preferably, the ratio of the outer diameter to the length of the connecting rod is 1:30.

[0011] Preferably, the throttling platform is a circular arc platform, and the upper surface of the circular arc platform is a plane with a width of 0.2 to 0.6 mm.

[0012] Preferably, the width of the plane is 0.4 mm.

[0013] Preferably, the cross-section of the throttling platform is an isosceles trapezoid, and the length of the plane is less than the overlap length between the throttling platform and the throttling section.

[0014] Preferably, the radius of the planar cross-section of the throttling platform is 0.92×r~0.96×r, where r is the radius of the cross-section of the circular arc platform.

[0015] Preferably, the number of throttling sections is three or four, and the surface of the throttling sections is either flat or concave.

[0016] Because of the adoption of the above technical solution, the present invention has the following advantages: The needle valve is integrated, eliminating the problems of clearance and unreliable force transmission between traditional components. During the transition phase of fuel injection opening or closing, the flow and pressure changes are regulated by setting a throttle body. The sudden changes in the needle valve's movement speed are slowed down by the elastic extension or bending deformation of the connecting rod. The throttle body and the connecting rod work together to improve the smoothness and reliability of the fuel injection control process. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the specific embodiments will be briefly introduced below. In all the drawings, the elements or parts are not necessarily drawn to scale.

[0018] Figure 1 This is a schematic diagram of the structure of a flexible integrated needle valve with a throttling structure according to the present invention; Figure 2 A schematic diagram of a high-pressure common rail injector; Figure 3 This is an enlarged schematic diagram of point A; Figure 4 A schematic diagram showing the needle valve section raised; Figure 5 This is a schematic diagram showing the needle valve fully raised.

[0019] Figure label: 1- Valve head, 11- Annular groove; 2- Valve tail, 21- Throttling section, 22- Throttling platform; 3- Connecting rod; 4- Solenoid valve assembly; 5-Armature assembly, 51-Metering valve, 52-Armature seat, 53-Armature shaft, 54-Armature shaft spring, 55-Switch valve; 6-Control valve sleeve, 61-Slot, 62-Control cavity; 7-Pressure regulating spring, 71-Pressure regulating spring seat; 8-Injector body, 81-First mounting cavity; 9-Needle valve body, 91-Second mounting cavity, 911-Upper cavity, 912-Lower cavity, 92-Spray hole, 93-Sealing cone surface. Detailed Implementation

[0020] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings.

[0021] Please see Figures 1 to 5 A flexible integrated needle valve with a throttling structure includes: a valve head 1, a valve tail 2, and an intermediate section connecting the valve head 1 and the valve tail 2. The intermediate section is a connecting rod 3 with elastic deformation capability. Several throttling sections 21 are spaced apart along the outer circumference of the valve tail 2. A throttling platform 22 is provided on the surface of the end of the throttling section 21 near the connecting rod 3, and each throttling platform 22 is on the same circumference. Specifically, the high-pressure common rail injector mainly includes components such as a solenoid valve assembly 4, an armature assembly 5, a control valve sleeve 6, a pressure regulating spring 7, an injector body 8, and a needle valve body 9. The armature assembly 5 includes a metering valve 51, an armature seat 52, an armature shaft 53, an armature shaft spring 54, and a switching valve 55. The injector body 8 is provided with a first mounting cavity 81 that matches the shape of the needle valve. The first mounting cavity 81 is a high-pressure cavity. The end face of the needle valve body 9 is pressed against the lower end face of the injector body 8. The needle valve body 9 is provided with several spray holes 92. The needle valve body 9 has a second mounting cavity 91 that matches the shape of the needle valve. The first mounting cavity 81 and the second mounting cavity 91 are coaxial. The needle valve is installed in the first mounting cavity 81 and the second mounting cavity 91 and moves axially along the first mounting cavity 81 and the second mounting cavity 91. The second mounting cavity 91 includes an upper cavity 911 and a lower cavity 912 that are interconnected. The control valve sleeve 6 is axially pressed on the upper part of the first mounting cavity 81 by the metering valve 51. The control valve sleeve 6 has a slot 61 along the axial direction. The valve head 1 matches the slot 61. One end of the pressure regulating spring 7 contacts the lower end face of the control valve sleeve 6, and the other end is connected to the needle valve and presses the needle valve tightly on the needle valve body sealing cone surface 93 inside the needle valve body 9. The armature shaft 53 is axially movable and is arranged in the middle hole of the solenoid valve assembly 4 and the armature seat 52. The armature assembly 5 presses the switch valve 55 tightly on the sealing plane of the oil outlet of the metering valve 51. The slot of the control valve sleeve 6 and the top of the needle valve form a control cavity 62. The working principle of the high-pressure common rail fuel injection system has long been disclosed in existing technology and will not be elaborated here.

[0022] The inner diameter of the upper cavity 911 is larger than that of the lower cavity 912, and the needle valve moves along the lower cavity 912 and the upper cavity 911. The position of the throttling platform 22 in the throttling section 21 is determined by the structure of the needle valve body 9, and it is located at the junction of the upper cavity 911 and the lower cavity 912. By matching the length of the throttling platform with the second mounting cavity 91, it is ensured that when the needle valve is closed, most of the throttling platform 22 is located in the lower cavity 912, and when the needle valve is fully raised, the throttling platform 22 is completely located in the upper cavity 911, with part of the throttling section 21 exposed in the upper cavity 911. The valve tail 2 functions the same as a conventional split-type needle valve; the valve head 1 functions the same as a conventional hydraulic plunger.

[0023] The throttling section 21 adopts the structure of existing technology, that is, a portion is cut off axially on the outer side of a section of the valve tail 2, and multiple throttling sections 21 are evenly spaced around the circumference of the valve tail 2. Based on engineering experience, it is preferable to set three or four throttling sections 21, which can be designed with planar or concave surfaces as needed. A flow section is formed between the throttling section 21 and the inner wall of the second mounting cavity 91, through which fuel can flow out through the injection hole 92. In this application, the number of throttling sections 21 is three, which are evenly distributed at 120° intervals around the circumference of the valve tail 2. The upper surface of the throttling section 21 is planar, forming the main throttling channel.

[0024] This invention discloses a flexible integrated needle valve with a throttling structure. It eliminates the traditional hydraulic plunger and push rod transmission mechanism, employing a compact integrated design that fundamentally eliminates the problems of clearance and unreliable force transmission between traditional components. The valve head 1 and valve tail 2 are located between the control chamber 62 and the second mounting chamber 91, respectively. This integrated structure enables direct force transmission, simplifies part shape and fitting requirements, and thus reduces the machining precision and cost of the components. Both the valve head 1 and valve tail 2 retain guide sealing sections to ensure the stability of the needle valve's movement and good sealing performance.

[0025] When the fuel injection signal pulse arrives, the switching valve 55 opens, the fuel pressure in the control chamber 62 drops rapidly, the needle valve lifts as a whole, and fuel is injected from the injection hole 92. In the initial stage of needle valve opening, the needle valve partially lifts, and the high-pressure fuel first passes through the flow channel formed by the throttling platform 22 and the inner wall of the lower chamber 912. Due to the presence of the throttling platform 22, the fuel entering the lower chamber 912 is throttled, reducing the flow rate. Therefore, the fuel is softened before entering the throttling section 21, resulting in more uniform oil pressure in the lower chamber 912, avoiding a "momentary opening" state. The flow rate of the injection hole 92 is effectively controlled, reducing sudden changes in the fuel injection rate and providing a relatively gentle starting pressure to the needle valve. The connecting rod 3 in the middle section of the needle valve undergoes slight deformation under oil pressure, absorbing the impact energy of the rising needle valve and slowing down the sudden change in the axial movement speed of the needle valve. The flow rate throttled by the throttling platform 22 is more stable. Therefore, the connecting rod 3 and the throttling platform 22 complement each other to suppress the impact of the opening transient. During the mid-injection phase, the needle valve fully lifts, and the throttling manifold 22 enters the upper chamber 911. The throttling manifold 22 no longer dominates the fuel flow; the throttling section 21 takes over the main flow control, ensuring a stable supply even at high flow rates. A large amount of fuel is injected into the combustion chamber through the injection orifice 92 without affecting the injection flow rate and efficiency. During the needle valve closing phase, the needle valve descends, and the throttling manifold 22 re-enters the lower chamber 912, gradually becoming the main flow path. The throttling manifold 22 provides greater flow resistance than the throttling section 21, significantly enhancing the damping during the closing process. Residual flow is released slowly, and the fuel pressure drops smoothly, effectively preventing oscillations caused by rapid pressure changes and providing a relatively gentle upward pressure to the needle valve. Simultaneously, the connecting rod 3 undergoes another slight deformation, absorbing some hydraulic or mechanical shock energy and suppressing the impact of the closing transient. This flow field regulation, characterized by softened opening and enhanced closing damping, reduces flow pulsation and impact fluctuations during fuel injection. The fuel injection quantity curve is initially gradual, then accelerates, and then gradually decreases again, with the overall injection flow rate exhibiting a "convex" curve. This avoids the impact-type injection characteristic of traditional straight needle injectors, improving the stability of the injection process. Throttling section 21 is responsible for maintaining injection stability under medium to high loads, while throttling platform 22 controls the smooth opening and closing of the flow rate during the low flow stage, acting as a secondary throttling mechanism. When the needle valve opens or closes rapidly under high pressure, the connecting rod 3 can undergo slight bending or extension, effectively mitigating the hard metal-to-metal collision between the needle valve and the valve body, reducing noise and impact stress. Simultaneously, the deformation of the connecting rod 3 at the beginning and end of the injection process makes the needle valve operation more stable, working in conjunction with throttling platform 22 to reduce sudden changes in fuel flow.

[0026] Furthermore, the connecting rod 3 is welded to the valve head 1 and valve tail 2 respectively. Specifically, the needle valve is integrally formed by welding after a transition fit, which ensures overall strength and prevents loosening during high-frequency opening and closing. The connecting rod 3 is made of steel with certain elasticity and fatigue resistance. Under high pressure and impact loads, the connecting rod 3 can undergo slight elastic deformation but can recover without permanent plastic deformation. Preferably, the material of the connecting rod 3 is 16CrMn.

[0027] Furthermore, the ratio of the outer diameter to the length of the connecting rod 3 is 1:35 to 1:25. The flexibility of the connecting rod 3 is achieved through the coordination between its slender structure and the elastic modulus and yield strength of the material. The purpose is that the slender rod can undergo slight elastic expansion or bending deformation under high-pressure fuel and mechanical impact. The connecting rod 3 is located in the middle of the needle valve and does not participate in sealing or fitting, thus not affecting the sealing effect and guiding accuracy between the needle valve end and the valve body. During the up-and-down movement of the needle valve, the deformation of the connecting rod 3 is very small, serving only a buffering function and not causing hysteresis or a decrease in control accuracy. If the ratio of the outer diameter to the length is less than 1:35, the flexibility is high, posing a risk of hysteresis or a decrease in control accuracy; while if it is greater than 1:25, the flexibility is low, with small elastic expansion or bending deformation, failing to effectively provide a buffering effect. In this application, the length of the connecting rod 3 is 90 mm and the diameter is 3 mm, meaning the ratio of the length to the outer diameter of the connecting rod 3 is 1:30. This ratio has been verified; the connecting rod 3 can elastically expand or bend under external force for approximately a few micrometers, thereby forming an effective buffer.

[0028] Furthermore, the throttling platform 22 is an arc-shaped platform, and the upper surface of the arc-shaped platform is a plane with a width of 0.2~0.6mm. Specifically, in the existing throttling structure, a small section of a complete outer circle is retained at intervals on the surface of the throttling section 21 to form an arc-shaped platform, and a very shallow plane is cut out on this outer circle with an axial width of 0.2~0.6mm. Experimental verification shows that if the width is less than 0.2mm, not only is the processing difficult, but the throttling effect is also lost; if the width is greater than 0.6mm, the contact area with the inner wall of the second mounting cavity is too large, leading to jamming or excessive wear. Preferably, the width of the plane is 0.4mm, which can balance the ease of processing and effectively prevent the throttling platform 22 from jamming or wearing.

[0029] Furthermore, the cross-section of the throttling platform 22 is an isosceles trapezoid, and the length of the plane is less than the overlap length between the throttling platform 22 and the throttling section 21. Specifically, the throttling platform 22 and the valve tail 2 are integrally formed, and the surfaces of the throttling platform and the throttling section 21 are formed by grinding. This structure enhances the strength between the throttling platform 22 and the throttling section 21.

[0030] Furthermore, the radius of the planar cross-section of the throttling platform 22 is 0.92×r~0.96×r, where r is the radius of the arc-shaped platform. Specifically, the diameter of the arc-shaped platform is determined by the diameter of the lower cavity 912. For example, if the diameter of the lower cavity 912 is φ5mm, then the diameter of the arc-shaped platform is also φ5mm. The distance from the upper surface of the throttling section 21 to the central axis of the needle valve is 0.7×r~0.8×r, and the distance from the plane of the throttling platform 22 to the central axis of the needle valve is 0.92×r~0.96×r, that is, the distance from the plane of the throttling platform 22 to the inner wall of the lower cavity 912 is 0.1~0.2mm. The distance from the plane of the throttling platform 22 to the central axis of the needle valve directly affects the throttling effect. The smaller the distance, the stronger the throttling effect. However, if the distance is too small, it will cause the risk of jamming and affect the opening speed of the needle valve. Preferably, the radius of the plane of the throttling platform 22 is 0.935×r.

[0031] Furthermore, the valve head 1 is provided with an annular groove 11. Specifically, the valve head 1 has an annular groove 11 on the outer surface near the connecting rod 3 for installing an open retaining ring. A pressure adjusting spring seat 71 is installed on the open retaining ring, and then a pressure adjusting pad is installed on the pressure adjusting spring seat. One end of the pressure adjusting spring 7 contacts the lower end face of the control valve sleeve 6, and the other end contacts the pressure adjusting pad. Needle valves are usually made of high-strength, high-wear-resistant solid materials and have a large outer diameter. Setting the annular groove 11 on the needle valve has significant advantages. On the one hand, external processing is not limited by space, and positioning operations before processing are more convenient. On the other hand, the control of processing accuracy is easier, which can ensure the straightness and cylindricity of the annular groove 11, and accurately control the width and depth of the annular groove 11, thereby improving the installation accuracy of the pressure adjusting spring 7.

[0032] The needle valve's middle section is designed as a flexible, slender rod, giving it a certain degree of elastic deformation capability. During the transient process of needle valve activation or closure, fuel pressure acts on this slender section, causing it to undergo slight elastic deformation. The good elasticity of the slender rod can absorb some of the hydraulic or mechanical impact energy, acting as a buffer. This slight elastic deformation not only does not compromise the sealing performance but also helps to mitigate the abrupt change in needle valve movement speed during the transition phase between opening and closing, improving the smoothness and reliability of the control process. The mating section between the needle valve and the valve body is traditionally a three-flat square structure. This invention adds a small throttling structure to the three-flat square structure to control the oil circuit opening during the transient process of fuel injection activation and closure. This makes the oil flow gradient when the needle valve opening changes, resulting in smoother flow changes during activation or closure, achieving gentler control of the transient flow during the fuel injection process.

[0033] This invention utilizes a flexible, integrated needle valve with a throttling structure. During the transition phase of fuel injection opening or closing, a throttling platform 22 is incorporated to regulate flow and pressure changes, providing a buffer for the elastic extension, contraction, or bending deformation of the connecting rod 3. This elastic extension, contraction, or bending deformation of the connecting rod 3 mitigates sudden changes in the needle valve's movement speed, further ensuring the stability of the fuel flow rate through the throttling platform 22. Specifically, when opening, the needle valve begins to lift, and the fuel first passes through the throttling platform 22. The throttling platform 22 restricts the instantaneous large flow of fuel, resulting in a more stable flow rate. The outer diameter to length ratio of the connecting rod 3 is 1:35 to 1:25. The slender structure and the coordination between the elastic modulus and yield strength of the material achieve flexibility in the connecting rod 3. A plane with a width of 0.2 to 0.6 mm is axially provided on the surface of the throttling platform 22 to effectively prevent jamming or excessive wear. An annular groove 11 is provided on the valve head 1 to improve the installation accuracy of the pressure regulating spring 7.

[0034] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A flexible integrated needle valve with a throttling structure, characterized in that, include: The valve head (1), valve tail (2) and the middle section connecting the valve head (1) and valve tail (2) are connected by a connecting rod (3) with elastic deformation capability. Several throttling sections (21) are provided at intervals along the outer circumference of the valve tail (2). A throttling platform (22) is provided on the surface of the throttling section (21) near the connecting rod (3), and each throttling platform (22) is on the circumference of the same center.

2. The flexible integrated needle valve with a throttling structure according to claim 1, characterized in that, The connecting rod (3) is welded to the valve head 1 and the valve tail (2) respectively.

3. The flexible integrated needle valve with a throttling structure according to claim 1 or 2, characterized in that, The material of the connecting rod (3) is 16CrMn.

4. The flexible integrated needle valve with a throttling structure according to claim 1 or 2, characterized in that, The ratio of the outer diameter to the length of the connecting rod (3) is 1:35 to 1:

25.

5. The flexible integrated needle valve with a throttling structure according to claim 4, characterized in that, The ratio of the outer diameter to the length of the connecting rod (3) is 1:

30.

6. The flexible integrated needle valve with a throttling structure according to claim 1, 2, or 5, characterized in that, The throttling platform (22) is a circular arc platform, and the upper surface of the circular arc platform is a plane with a width of 0.2~0.6mm.

7. The flexible integrated needle valve with a throttling structure according to claim 6, characterized in that, The width of the plane is 0.4mm.

8. The flexible integrated needle valve with a throttling structure according to claim 6, characterized in that, The cross-section of the throttling platform (22) is an isosceles trapezoid, and the length of the plane is less than the overlap length between the throttling platform (22) and the throttling section (21).

9. The flexible integrated needle valve with a throttling structure according to claim 7 or 8, characterized in that, The cross-sectional radius of the throttling platform (22) is 0.92×r~0.96×r, where r is the cross-sectional radius of the circular arc platform.

10. The flexible integrated needle valve with a throttling structure according to claim 1, 2, 5, 7 or 8, characterized in that, The number of throttling sections (21) is three or four, and the surface of the throttling sections (21) is either flat or concave.

Images