Micro needle valve high-pressure common rail oil injector

Abstract

The utility model discloses a micro needle valve high-pressure common-rail oil injector, which can greatly reduce the weight and the motion inertia of a needle valve through an optimized micro needle valve and a hydraulic device control chamber sinking to the deep part of a fuel oil cavity in an oil nozzle. By means of the technical scheme, the weight of the needle valve can be smaller than 0.5 g, compared with a traditional technology, the length of the needle valve is greatly shortened, the diameter can be correspondingly reduced, and the weight is reduced by more than 85%. Even, in the embodiment of the scheme, the length of the needle valve is only 9.5 mm, the diameter of the head is 1.6 mm, the weight is only about 0.15 g, and compared with a traditional technology, the weight is reduced by about 95%. Obviously, by greatly reducing the weight of the needle valve, the response speed of fuel injection opening and closing control of the fuel injector is greatly increased, the performance of the fuel injector is more excellent, the structure is simple, and the cost is low.

Description

Technical Field

[0001] The invention relates to a high-pressure common rail fuel injector for engine fuel injection, in particular to a micro needle valve high-pressure common rail fuel injector. Background Art

[0002] The high-pressure common rail injector used for engine fuel injection is a device that uses a solenoid valve to control a hydraulic device, and the hydraulic device further controls a needle valve to realize the opening and closing of the injector fuel injection.

[0003] The high-pressure common rail injector includes a housing, a solenoid valve, a hydraulic device, a nozzle and a tight cap; the nozzle includes a nozzle body, a needle valve and a preload spring. There is a hollow fuel chamber inside the nozzle body, the needle valve is arranged in the fuel chamber, and a spray hole connected to the outside is provided at the lower end of the nozzle body.

[0004] The solenoid valve consists of a yoke, a coil, an armature and a return spring.

[0005] When the solenoid valve is energized, the coil generates an electromagnetic field, attracting the armature to overcome the force of the return spring, causing it to displace axially. To meet the requirements of high-speed engine control, this displacement is typically only tens of microns. The displacement and force generated by the solenoid valve are insufficient to directly drive the needle valve, so a hydraulic device is required to amplify the motion to hundreds of microns.

[0006] The hydraulic device consists of a valve, valve body, piston, and push rod. The valve body houses a control chamber, which is a cylindrical hole with an inverted opening. A piston is positioned within the control chamber and can slide axially. The control chamber is equipped with an oil inlet and outlet orifice. The valve is located at the outlet of the orifice, blocking it in normal operation. The piston is connected to a needle valve via a push rod and moves in sync with the needle valve.

[0007] When the high-pressure common rail injector is working, a certain fuel pressure is maintained in the fuel chamber of the nozzle body, but the injector will only spray fuel outward through the spray hole when the needle valve rises, and the injector will stop spraying fuel when the needle valve falls.

[0008] Controlling the power on and off of the solenoid valve controls the opening and closing of the fuel injector. Due to the high engine speed, precise control of fuel injection performance places very high demands on the response speed of the solenoid valve armature and the nozzle needle.

[0009] Application numbers 2024113875382 and 2024224051555 optimize the solenoid valve. By adopting a snap-on solenoid valve with a lever effect, the inertia of the moving parts of the solenoid valve is greatly optimized, and the response speed and energy conversion efficiency of the solenoid valve are improved.

[0010] However, in addition to the solenoid valve, the needle valve, which turns the fuel injection on and off, is also crucial to the overall injector control response speed. Current needle valves must penetrate the entire fuel chamber within the nozzle, leaving the thrust end face of the needle valve head exposed or flush with the nozzle body's upper end face. This results in a relatively long needle valve. Furthermore, due to the need for rod stability, the needle valve's diameter cannot be too small. Consequently, the current needle valve's weight and moment of inertia are significant, hindering further improvements in the injector's fuel injection response speed. Summary of the Invention

[0011] The present invention aims to provide a micro-needle valve high-pressure common rail injector. By utilizing an optimized micro-needle valve and a hydraulic control chamber sunk deep into the fuel chamber within the nozzle, this significantly reduces the needle valve's weight and inertia. This significant reduction in needle valve weight significantly improves the injector's response speed during on / off control, resulting in superior injector performance and a simple, low-cost design.

[0012] To achieve this object, the present invention adopts the following technical solutions.

[0013] The invention provides a micro needle valve high pressure common rail injector, comprising a housing, a solenoid valve, a hydraulic device, a nozzle and a tight cap. The tight cap mounts the solenoid valve, the hydraulic device and the nozzle on the housing.

[0014] The solenoid valve consists of a yoke, a return spring, an armature and a coil.

[0015] The fuel nozzle includes a nozzle body, a needle valve and a preload spring. There is a hollow fuel chamber inside the nozzle body, and a spray hole connected to the outside is provided at the lower end of the nozzle body. The needle valve and the preload spring are both arranged in the fuel chamber. The preload spring acts on the needle valve from below, so that the sealing cone surface at the lower end of the needle valve remains closed to the spray hole entrance under normal conditions.

[0016] The hydraulic device includes a valve, a valve body, a control chamber and a piston; a slender rod is provided under the valve body, which extends deep into the fuel cavity of the nozzle, and an oil outlet throttling hole is provided inside the valve body along the axial direction of the slender rod. One end of the oil outlet throttling hole is connected to the valve above the valve body, and the other end passes through the lower end face of the slender rod and communicates with the interior of the control chamber; the control chamber is an independent component, in the shape of a sleeve, with a cylindrical hole inside, and the piston is arranged in the control chamber and can slide axially and maintain a coupled seal; the lower end face of the control chamber contacts the top of the nozzle preload spring, and under the action of the preload spring force, the upper end face of the control chamber contacts the lower end face of the slender rod of the valve body; the upper end face of the control chamber and the lower end face of the slender rod of the valve body are both precision planes, and the two planes can slide laterally to maintain a sealing trend under the action of the preload spring force.

[0017] The upper end of the needle valve is integrated with the piston of the hydraulic device, and the axial projection area of ​​the maximum sealing line of the lower end sealing cone of the needle valve is smaller than the upper end of the needle valve, that is, the top area of ​​the piston of the hydraulic device.

[0018] The hydraulic device is provided with an oil inlet throttling groove to keep the interior of the control chamber and the fuel cavity of the nozzle open. The oil inlet throttling groove is arranged on the upper end surface of the control chamber, or on the lower end surface of the slender stem of the valve body, or on the end of the slender stem of the valve body near the control chamber.

[0019] When the solenoid valve is energized, the coil generates an electromagnetic field that attracts the armature, pushing the valve open due to the fuel pressure in the outlet orifice below, releasing pressure in the control chamber. When the pressure in the control chamber falls below a threshold, the fuel pressure in the fuel chamber pushes the needle valve upward, opening the spray hole and allowing the injector to begin spraying. When the solenoid valve is de-energized, the armature, under the force of the return spring, pushes the valve of the hydraulic device to close the outlet orifice. Fuel in the fuel chamber flows into the control chamber through the hydraulic device's inlet orifice groove. The pressure in the control chamber rises, pushing the needle valve back into its seat, and the injector stops spraying.

[0020] By applying the above technical solution, the needle valve can weigh less than 0.5g. Compared with traditional technology, the length of the needle valve can be significantly shortened, and the diameter can be reduced accordingly, resulting in a weight reduction of more than 85%, and in some applications, even 95%.

[0021] Beneficial effects of the present invention:

[0022] By optimizing the micro needle valve and integrating a hydraulic control chamber sunk deep into the fuel chamber of the nozzle, the needle valve's weight and moment of inertia are significantly reduced. This significant reduction in needle valve weight significantly improves the injector's response speed when opening and closing injection, resulting in superior injector performance and a simpler, lower-cost design. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic structural diagram of a micro needle valve high-pressure common rail injector according to embodiment 1 of the present invention.

[0024] Figure 2 yes Figure 1 Schematic diagram of the locally enlarged structure of area A in the middle.

[0025] Figure 3 It is a partially enlarged structural schematic diagram of a micro needle valve high-pressure common rail injector according to the second embodiment of the present invention.

[0026] In the figure: 1-housing 1; 2-solenoid valve; 2a-yoke; 2b-reset spring; 2c-armature; 2d-coil; 3-hydraulic device; 3a-valve; 3b-valve body; 3c-oil outlet throttle hole; 3d-oil inlet throttle groove; 3e-piston; 3f-slender rod; 3g-control chamber; 4-nozzle; 4a-fuel chamber; 4b-nozzle body; 4c-needle valve; 4e-head; 4f-preload spring; 4d-spray hole; 5-tightening cap. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0028] In the description of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0029] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0030] In the description of this embodiment, terms such as "upper," "lower," "left," and "right" are used to refer to positions or locations based on those shown in the accompanying drawings. These terms are intended solely to facilitate description and simplify operation, and are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meaning. Example 1

[0031] like Figure 1~Figure 2The embodiment 1 is shown. The present invention provides a high-pressure common rail injector, comprising a housing 1, a solenoid valve 2, a hydraulic device 3, a nozzle 4 and a cap 5, wherein the cap 5 mounts the solenoid valve 2, the hydraulic device 3 and the nozzle 4 on the housing 1.

[0032] The solenoid valve 2 includes a yoke 2a, a return spring 2b, an armature 2c, and a coil 2d.

[0033] The fuel nozzle 4 includes a nozzle body 4b, a needle valve 4c and a preload spring 4f. The nozzle body 4b has a hollow fuel chamber 4a inside, and a spray hole 4d connected to the outside is provided at the lower end of the nozzle body 4. The needle valve 4c and the preload spring 4f are both arranged in the fuel chamber 4a. The preload spring 4f acts on the needle valve 4c from below, so that the sealing cone surface at the lower end of the needle valve 4c keeps the inlet of the spray hole 4d closed under normal conditions.

[0034] The hydraulic device 3 includes a valve 3a, a valve body 3b, a control chamber 3g and a piston 3e; a slender rod 3f is provided below the valve body 3b, and the slender rod 3f extends deep into the fuel chamber 4a of the oil nozzle 4. An oil outlet throttle hole 3c is provided inside the valve body 3b along the axial direction of the slender rod 3f. One end of the oil outlet throttle hole 3c is connected to the valve 3a above the valve body 3b, and the other end passes through the lower end surface of the slender rod 3f and communicates with the interior of the control chamber 3g; the control chamber 3g is an independent component in the shape of a sleeve, and its interior The top of the control chamber 3g is a cylindrical hole, and the piston 3e is arranged in the control chamber 3g and can slide axially and maintain a coupled seal; the lower end surface of the control chamber 3g contacts the top of the preload spring 4f of the oil nozzle 4, and under the action of the force of the preload spring 4f, the upper end surface of the control chamber 3g contacts the lower end surface of the slender rod 3f of the valve body 3b; the upper end surface of the control chamber 3g and the lower end surface of the slender rod 3f of the valve body 3b are both precision planes, and the two planes can slide laterally and maintain a sealing trend under the action of the force of the preload spring 4f.

[0035] The upper end head 4e of the needle valve 4c is integrated with the piston 3e of the hydraulic device 3, and the axial projection area of ​​the maximum sealing line of the lower end sealing cone surface of the needle valve 4c is smaller than the upper end head 4e of the needle valve 4c, that is, the top area of ​​the piston 3e of the hydraulic device 3.

[0036] The hydraulic device 3 is provided with an oil inlet throttling groove 3d, which ensures constant communication between the interior of the control chamber 3g and the fuel chamber 4a of the nozzle 4. The oil inlet throttling groove 3d is located on the upper end surface of the control chamber 3g, or on the lower end surface of the elongated stem 3f of the valve body 3b, or on the end of the elongated stem 3f of the valve body 3b near the control chamber 3g. In this embodiment, the oil inlet throttling groove 3d is located on the upper end surface of the control chamber 3g.

[0037] When solenoid valve 2 is energized, coil 2d generates an electromagnetic field that attracts armature 2c. Valve 3a is pushed open by the fuel pressure within the outlet orifice 3c below, releasing pressure within control chamber 3g. When the pressure within control chamber 3g falls below a threshold, the fuel pressure within fuel chamber 4a pushes needle valve 4c upward, opening the inlet of spray hole 4d and initiating fuel injection. When solenoid valve 2 is de-energized, armature 2c, under the force of return spring 2b, pushes valve 3a of hydraulic device 3 to close outlet orifice 3c. Fuel within fuel chamber 4a flows through inlet orifice groove 3d of hydraulic device 3 into control chamber 3g. The pressure in control chamber 3g rises, pushing needle valve 4c into its seat and halting fuel injection. Example 2

[0038] The difference from the first embodiment is that the oil inlet throttling groove 3d of this embodiment is arranged at the end of the slender rod 3f of the valve body 3b close to the control chamber 3g, as shown in FIG. Figure 3 The oil inlet throttle groove 3d is a small hole that communicates with the oil outlet throttle hole 3c, so that the interior of the control chamber 3g and the fuel cavity 4a of the oil nozzle 4 are always connected.

[0039] In the above embodiment, the needle valve 4c is 9.5 mm long, the head 4e is 1.6 mm in diameter, and weighs only about 0.15 g. Compared with conventional technology, the needle valve 4c is significantly shorter in length, significantly smaller in diameter, and weighs about 95% less.

[0040] Moreover, from Figures 1 to 3 It can be seen that the structure is simple and the cost is low.

[0041] Obviously, the above-described embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. A person skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A micro needle valve high-pressure common rail injector, comprising a housing (1), a solenoid valve (2), a hydraulic device (3), a nozzle (4) and a tight cap (5), wherein the tight cap (5) press-fits the solenoid valve (2), the hydraulic device (3) and the nozzle (4) onto the housing (1), and the solenoid valve (2) comprises a yoke (2a), a return spring (2b), an armature (2c) and a coil (2d), and is characterized in that: The oil nozzle (4) includes a nozzle body (4b), a needle valve (4c) and a preload spring (4f); a hollow fuel cavity (4a) is provided inside the nozzle body (4b); a spray hole (4d) communicating with the outside is provided at the lower end of the nozzle body (4b); the needle valve (4c) and the preload spring (4f) are both provided in the fuel cavity (4a); the preload spring (4f) acts on the needle valve (4c) from below, so that the sealing cone surface at the lower end of the needle valve (4c) keeps the inlet of the spray hole (4d) closed under normal conditions; The hydraulic device (3) comprises a valve (3a), a valve body (3b), a control chamber (3g) and a piston (3e); a slender rod (3f) is provided below the valve body (3b), and the slender rod (3f) extends deep into the fuel cavity (4a) of the oil nozzle (4); an oil outlet throttling hole (3c) is provided inside the valve body (3b) along the axial direction of the slender rod (3f); one end of the oil outlet throttling hole (3c) is connected to the valve (3a) above the valve body (3b), and the other end passes through the lower end surface of the slender rod (3f) and communicates with the inside of the control chamber (3g); the control chamber (3g) is an independent component, which is in the form of a sleeve. The piston (3e) is arranged in a control chamber (3g) and can slide axially and maintain a coupled seal; the lower end surface of the control chamber (3g) contacts the upper side of the preload spring (4f) of the oil nozzle (4), and under the action of the force of the preload spring (4f), the upper end surface of the control chamber (3g) contacts the lower end surface of the slender rod (3f) of the valve body (3b); the upper end surface of the control chamber (3g) and the lower end surface of the slender rod (3f) of the valve body (3b) are both precision planes, and the two planes can slide laterally and maintain a sealing tendency under the action of the force of the preload spring (4f); The upper end head (4e) of the needle valve (4c) is integrated with the piston (3e) of the hydraulic device (3), and the axial projection area of ​​the maximum sealing line of the sealing cone surface at the lower end of the needle valve (4c) is smaller than the top area of ​​the upper end head (4e) of the needle valve (4c), i.e., the top area of ​​the piston (3e) of the hydraulic device (3).

2. The micro needle valve high pressure common rail injector according to claim 1, characterized in that: The hydraulic device (3) is provided with an oil inlet throttling groove (3d) so that the interior of the control chamber (3g) and the fuel cavity (4a) of the oil nozzle (4) are kept in constant communication; the oil inlet throttling groove (3d) is provided on the upper end surface of the control chamber (3g), or on the lower end surface of the slender rod (3f) of the valve body (3b), or on the end of the slender rod (3f) of the valve body (3b) close to the control chamber (3g).

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