Micro needle valve high-pressure common rail oil injector

Abstract

The invention 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 comprises a housing, a solenoid valve, a hydraulic device, a nozzle and a tight cap; the nozzle comprises a nozzle body, a needle valve and a preload spring, the nozzle body has a hollow fuel cavity inside, the needle valve is arranged in the fuel cavity, and the lower end of the nozzle body is provided with a spray hole connected to the outside.

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

[0005] When the solenoid valve is energized, the coil generates an electromagnetic field, which attracts the armature to overcome the elastic force of the return spring and cause displacement along the armature axis. To meet the needs of high-speed engine control, the displacement is generally only about tens of microns. The displacement and force generated by the solenoid valve cannot directly drive the needle valve, so it is necessary to introduce a hydraulic device that can amplify the action to hundreds of microns.

[0006] The hydraulic device includes a valve, a valve body, a piston and a push rod; a control chamber is arranged in the valve body, and the control chamber is a cylindrical hole with an inverted opening. The piston is arranged in the control chamber and can slide axially. The control chamber is provided with an oil inlet throttle hole and an oil outlet throttle hole. The valve is arranged at the outlet of the oil outlet throttle hole, and blocks the outlet of the oil outlet throttle hole in normal state. The piston is connected to the needle valve through the push rod, and is basically synchronized with the movement of 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 can control the opening and closing of the fuel injector. Due to the high engine speed, in order to accurately control the fuel injection performance, very high requirements are placed on the response speed of the solenoid valve armature and the nozzle needle valve.

[0009] Application Nos. 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 responsible for opening and closing the injection is also crucial to the response speed of the entire injector control. The needle valve in the current technology needs to pass through the entire fuel cavity inside the nozzle so that the thrust end face of the needle valve head is exposed or basically flush with the upper end face of the nozzle body, so the needle valve is relatively long; on the other hand, due to the need for stability of the pressure rod, the needle valve diameter cannot be too small. Therefore, in the current technology, the weight and motion inertia of the needle valve are relatively large, which is not conducive to further improving the response speed of the injector injection opening and closing control. Summary of the invention

[0011] The purpose of the present invention is to provide a micro needle valve high pressure common rail injector, which can significantly reduce the weight and motion inertia of the needle valve by optimizing the micro needle valve and combining the hydraulic device control chamber sunk deep into the fuel cavity in the nozzle. By significantly reducing the weight of the needle valve, the response speed of the injector's fuel injection opening and closing control is also greatly improved, the injector has better performance, and the structure is simple and low cost.

[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 fuel injector, comprising a housing, a solenoid valve, a hydraulic device, a nozzle and a tight cap, wherein the solenoid valve, the hydraulic device and the nozzle are mounted on the housing by the tight cap.

[0014] The solenoid valve includes 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. A spray hole connected to the outside is arranged 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 keeps the spray hole entrance closed under normal conditions.

[0016] The hydraulic device includes a valve, a valve body, a control chamber and a piston; a slender rod is arranged below the valve body, and the slender rod extends deep into the fuel cavity of the nozzle; an oil outlet throttling hole is arranged 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 surface of the slender rod and communicates with the inside of the control chamber; the control chamber is an independent component, in the shape of a sleeve, and has a cylindrical hole inside; the piston is arranged in the control chamber and can slide axially and maintain a coupled seal; the lower end surface of the control chamber contacts the top of the nozzle preload spring, and under the action of the preload spring force, the upper end surface of the control chamber contacts the lower end surface of the slender rod of the valve body; the upper end surface of the control chamber and the lower end surface of the slender rod of the valve body are both precision planes, and the two planes can slide laterally to maintain a sealing tendency 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 inside of the control chamber and the fuel cavity of the oil 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 rod of the valve body, or on the end of the slender rod of the valve body close to the control chamber.

[0019] When the solenoid valve is powered on, the coil generates an electromagnetic field to attract the armature, and the valve is pushed open by the fuel pressure in the oil outlet throttle hole below, and the pressure in the control chamber is released. When the pressure in the control chamber is lower than the threshold, the fuel pressure in the fuel chamber pushes the needle valve upward, the nozzle inlet is opened, and the injector starts to spray fuel. When the solenoid valve is powered off, the armature, under the action of the return spring force, pushes the valve of the hydraulic device to close the oil outlet throttle hole, and the fuel in the fuel chamber flows into the control chamber through the oil inlet throttle groove of the hydraulic device. The pressure in the control chamber rises, pushing the needle valve to seat, and the injector stops spraying fuel.

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

[0021] Beneficial effects of the present invention: The optimized micro needle valve, combined with the hydraulic control chamber sunk deep into the fuel cavity of the nozzle, can significantly reduce the weight and motion inertia of the needle valve. By significantly reducing the weight of the needle valve, the response speed of the injector's fuel injection opening and closing control is also greatly improved, the injector performance is more superior, and the structure is simple and cost-effective. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a schematic structural diagram of a micro needle valve high pressure common rail injector according to an embodiment of the present invention.

[0023] Figure 2 yes Figure 1 Schematic diagram of the local enlarged structure of area A in the middle.

[0024] Figure 3 It is a partial enlarged structural schematic diagram of a micro needle valve high pressure common rail injector according to the second embodiment of the present invention.

[0025] 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 throttling hole; 3d-oil inlet throttling groove; 3e-piston; 3f-slender rod; 3g-control chamber; 4-oil nozzle; 4a-fuel chamber; 4b-nozzle body; 4c-needle valve; 4e-head; 4f-preload spring; 4d-spray hole; 5-tightening cap. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0027] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0029] In the description of this embodiment, the terms "upper", "lower", "left", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning. Embodiment 1

[0030] 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.

[0031] The solenoid valve 2 includes a yoke 2a, a return spring 2b, an armature 2c, and a coil 2d.

[0032] 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. The lower end of the nozzle body 4 is provided with a spray hole 4d connected to the outside. 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.

[0033] 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 arranged 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 throttling hole 3c is arranged 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 in the shape of a sleeve, and its inner The piston 3e is arranged in the control chamber 3g and can slide axially and maintain the coupling 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 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 the sealing tendency under the action of the preload spring 4f.

[0034] 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.

[0035] 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 chamber 4a of the oil nozzle 4 are always connected. The oil inlet throttling groove 3d is arranged 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. The oil inlet throttling groove 3d of this embodiment is arranged on the upper end surface of the control chamber 3g.

[0036] When the solenoid valve 2 is powered on, the coil 2d generates an electromagnetic field to attract the armature 2c, and the valve 3a is pushed open by the fuel pressure in the oil outlet throttle hole 3c below, and the pressure in the control chamber 3g is released. When the pressure in the control chamber 3g is lower than the threshold, the fuel pressure in the fuel chamber 4a pushes the needle valve 4c upward, the inlet of the spray hole 4d is opened, and the injector starts to spray fuel. When the solenoid valve 2 is powered off, the armature 2c pushes the valve 3a of the hydraulic device 3 to close the oil outlet throttle hole 3c under the action of the return spring force 2b, and the fuel in the fuel chamber 4a flows into the control chamber 3g through the oil inlet throttle groove 3d of the hydraulic device 3. The pressure in the control chamber 3g rises, pushing the needle valve 4c to seat, and the injector stops spraying fuel. Embodiment 2

[0037] 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 throttling groove 3d is a small hole connected to the oil outlet throttling hole 3c, so that the inside of the control chamber 3g and the fuel cavity 4a of the oil nozzle 4 are always connected.

[0038] 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 the conventional technology, the needle valve 4c is significantly shorter in length, significantly smaller in diameter, and reduced in weight by about 95%.

[0039] Moreover, from Figure 1~Figure 3 It can be seen that the structure is simple and the cost is low.

[0040] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope 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 cap (5), wherein the cap (5) presses the solenoid valve (2), the hydraulic device (3) and the nozzle (4) onto the housing (1), the solenoid valve (2) comprising a yoke (2a), a return spring (2b), an armature (2c) and a coil (2d), wherein: The oil nozzle (4) comprises a nozzle body (4b), a needle valve (4c) and a preload spring (4f); the nozzle body (4b) has a hollow fuel cavity (4a) inside; the lower end of the nozzle body (4) is provided with a spray hole (4d) communicating with the outside; the needle valve (4c) and the preload spring (4f) are both arranged in the fuel cavity (4a); the lower end of the preload spring (4f) acts on the needle valve (4c) 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 arranged below the valve body (3b), the slender rod (3f) extends deep into the fuel chamber (4a) of the oil nozzle (4); an oil outlet throttling hole (3c) is arranged 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, in the form of a sleeve The piston (3e) is arranged in a control chamber (3g) and can slide axially and maintain a coupling 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 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 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 piston (3e) of the hydraulic device (3).

2. The micro needle valve high pressure common rail injector according to claim 1 is 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 chamber (4a) of the oil nozzle (4) are always connected; the oil inlet throttling groove (3d) is arranged 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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