CN112879191A

CN112879191A - Surface texture guide sealing needle valve for high-pressure oil injector

Info

Publication number: CN112879191A
Application number: CN202110057127.7A
Authority: CN
Inventors: 罗福强; 金天宇; 吴习文; 王楚翘; 罗彤; 孙雨
Original assignee: Jiangsu University
Current assignee: Jiangsu University
Priority date: 2021-01-15
Filing date: 2021-01-15
Publication date: 2021-06-01

Abstract

The invention discloses a surface texture guide sealing needle valve for a high-pressure oil sprayer, wherein the needle valve is a stepped shaft and sequentially comprises a needle valve guide part, a needle valve middle section and a sealing conical surface from top to bottom, and a pressure-bearing conical surface is arranged between the needle valve guide part and the needle valve middle section; processing the surface of the needle valve guide part into a textured surface; according to the invention, the surface textures distributed in an array mode are processed on the needle valve guide part, so that the fluid dynamic pressure effect generated by a convergence area formed at the texture position can prevent the leakage of fuel oil and improve the sealing property, and meanwhile, a continuous oil film can improve the lubricating level.

Description

Surface texture guide sealing needle valve for high-pressure oil injector

Technical Field

The invention relates to the field of design of a guide sealing structure of a high-pressure precision matching part, in particular to a surface texture guide sealing needle valve for a high-pressure oil sprayer.

Background

With the stricter emission regulations, higher requirements are put on the high-pressure common rail electronic control injection technology of the diesel engine. The oil injection pressure is continuously improved to 200MPa or even higher. In diesel fuel delivery systems, the fuel injector is the key component for precisely metering fuel and forming a spray, and the needle valve assembly is one of the key assemblies.

In order to achieve high-pressure injection in common rail injection systems, the sealing of the injectors is of critical importance. Various forms of sealing exist for fuel injectors, including ways of providing a sealing valve in a cavity, mounting a combined sealing shell on a fuel injector assembly, or using a sealing gasket. And also includes high-pressure static seal and dynamic seal. The needle valve and the inner hole of the needle valve body generate relative axial movement constantly, oil injection is realized during opening and closing, and the needle valve also belongs to sliding fit and dynamic seal. The two parts are in sliding fit, and a gap is inevitably formed. The clearance is too small, the reciprocating motion cannot be reliably realized, and abrasion is easily generated, while the clearance is too large, fuel leakage is inevitably increased, the needle valve is deformed in the sliding process, and fuel pressure is difficult to establish. The traditional needle valve guide surface sealing is difficult to give consideration to guide, sealing and lubrication and improve the transient characteristic of the oil injector.

For a slip fit, a surface textured seal is used. The surface texture is a micro pit or micro groove lattice processed on the surface of the solid according to a certain size and an arrangement sequence, and the micron-sized texture forming a certain angle with the motion direction can generate a microscopic fluid dynamic pressure effect in a convergence area, so that the sliding is ensured and the leakage of fuel oil is reduced.

Patent publication No. CN110939539A entitled seal structure for fuel injector, discloses a fuel injector assembly including two mounting combination seal housings, a gasket, and a pipe joint. The oil sprayer is relatively low in development cost, simple in assembly and suitable for complex shapes of oil sprayers. The oil sprayer has the disadvantages that the oil sprayer is only sealed externally, and the precision matching parts cannot be sealed in the working process of the oil sprayer.

The patent publication No. CN 100412353 discloses a sealing device of a high-pressure common rail fuel injector. The high-pressure common rail oil injector mainly comprises a high-pressure common rail oil injector body, a wedge-shaped sealing ring and a valve sleeve. A wedge-shaped sealing ring is arranged at the lower end of an annular space formed between an inner hole of the injector body and the minimum outer cylindrical surface of the valve sleeve. The valve sleeve in the high-pressure common rail oil sprayer and the inner hole shaft of the oil sprayer are reliably sealed in a clearance mode, so that the liquid in the annular groove is guaranteed to establish ultrahigh pressure. The defect is that the guide lubrication and the sealing can not be realized at the same time.

Disclosure of Invention

In order to solve the defects in the prior art, the invention designs a surface texture guide sealing needle valve for a high-pressure oil sprayer; the needle valve coupler has the advantages of taking account of the sealing problem and the guide lubrication between the needle valve and the needle valve body in the movement process of the needle valve coupler.

The technical scheme adopted by the invention is as follows:

a surface texture guide sealing needle valve for a high-pressure oil injector is characterized in that the needle valve is a stepped shaft and sequentially comprises a needle valve guide part, a needle valve middle section and a sealing conical surface from top to bottom, and a pressure-bearing conical surface is arranged between the needle valve guide part and the needle valve middle section; the surface of the needle guide portion is machined to a textured surface.

Further, the textured surface is formed by processing an array of surface textures on the surface of the needle valve guide portion.

Further, the shape of the surface texture is circular, rhombic, square or elliptical;

further, the unit area occupancy rate S of each surface texture_pLess than 0.2;

further, the occupancy of unit area

L₁Is the center-to-center distance of the adjacent surface texture.

Further, an array distribution surface texture is processed on the surface of the needle valve guide part by adopting a laser processing method.

Furthermore, the needle valve body is in clearance fit with the needle valve guide part, and the clearance delta is kept between 1 and 5 mu m.

The invention has the beneficial effects that:

(1) compared with the existing needle valve with a smooth surface, the needle valve with the surface texture guide sealing structure has the advantages that the leakage amount of fuel oil is reduced and the sealing performance of the fuel oil is improved under the condition of lubricating in the relative sliding of the needle valve and the needle valve body. The bearing capacity is improved, and the high-pressure working condition is adapted.

(2) Because the surface texture is processed on the needle valve, the lubricating property of the sliding part of the needle valve can be enhanced, the sliding resistance is reduced, the response time of opening and closing the needle valve is shortened, and the transient response property of the fuel injector is improved.

(3) The abrasion between the needle valve and the needle valve body is reduced, the deformation of the needle valve in the movement process is reduced, and the oil injection stability is improved. The service life of the needle valve matching part is prolonged, and the reliability of the needle valve matching part is enhanced.

(4) The surface of the needle valve guide part is subjected to texture processing, so that the structure is simple, the processing is easy, and the cost is low.

(5) The needle valve guide sealing performance is improved, so that the capability of the fuel injector for adapting to fuels with different physical properties (such as methanol and the like) is enhanced.

Drawings

FIG. 1 is a cross-sectional view of a needle valve construction of the present invention;

FIG. 2 is a partially enlarged view of the textured surface of the needle guide portion;

FIG. 3 is a schematic view of a circular texture;

in the figure, 1, a needle valve body, 2, a needle valve guide part, 3, a pressure-bearing conical surface, 4, a needle valve middle section, 5, a sealing conical surface, 6 and an oil inlet channel.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in fig. 1, the surface texture guide sealing needle valve for the high-pressure fuel injector is characterized in that the needle valve is a stepped shaft and sequentially comprises a needle valve guide part 2, a needle valve middle section 4 and a sealing conical surface 5 from top to bottom, and a pressure-bearing conical surface 3 is arranged between the needle valve guide part 2 and the needle valve middle section 4; the surface of the needle guide portion 2 is processed into a textured surface.

Texturing the entire surface of the needle guide part 2, and processing the surface of the needle guide part 2 by laser processingA surface texture of the column distribution; the shape of the surface texture specifically adopts pits with shapes of circle, rhombus, square, ellipse and the like. And the center distance between adjacent surface textures is L₁And ensuring that the unit area occupancy rate of the surface texture is S_pLess than 0.2; the depth of the concave pit is 2-10 mu m according to the fit clearance between the needle valve guide part 2 and the needle valve body 1.

In this embodiment, a circular surface texture is taken as an example for explanation, and the center-to-center distance between adjacent circular textures is L as shown in FIG. 3₁. The radius of the circular texture is r, and the pit depth of the circular pits is 0.05 r-0.25 r. The calculation method of the unit area occupancy of the circular pits comprises the following steps:

the needle valve is assembled in the needle valve body 1, the needle valve body 1 shown in figure 1 is axially provided with a stepped hole, the needle valve body 1 is provided with an oil inlet channel 6, the bottom end of the oil inlet channel 6 is communicated with the stepped hole of the needle valve body 1, and oil is injected into the needle valve body 1 through the oil inlet channel 6. The needle valve body 1 and the needle valve guide part 2 are in clearance fit, and the clearance between the needle valve body 1 and the needle valve guide part 2 is delta and is kept in the range of 1-5 mu m. Because oil exists between the upper part of the needle valve body 1 and the needle valve guide part 2, an axial sealing surface is formed by the oil film between the needle valve and the needle valve body 1, and the lubricating level is improved.

Due to the action of the surface texture, the fluid dynamic pressure effect generated in the convergence area formed at the texture position can prevent the leakage of fuel oil and improve the bearing capacity. Meanwhile, in the moving friction process of the needle valve up and down, a continuous oil film is formed between the needle valve body 1 and the needle valve to improve the lubrication level and reduce the friction resistance. The dynamic response characteristic of the needle valve movement is enhanced, the deformation of the needle valve is reduced, and the eccentric movement of the needle valve is avoided.

The above embodiments are only used for illustrating the design idea and features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the content of the present invention and implement the present invention accordingly, and the protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes and modifications made in accordance with the principles and concepts disclosed herein are intended to be included within the scope of the present invention.

Claims

1. A surface texture guide sealing needle valve for a high-pressure oil injector is characterized in that the needle valve is a stepped shaft and sequentially comprises a needle valve guide part (2), a needle valve middle section (4) and a sealing conical surface (5) from top to bottom, and a pressure-bearing conical surface (3) is arranged between the needle valve guide part (2) and the needle valve middle section (4); the surface of the needle valve guide portion (2) is machined to a textured surface.

2. The surface texture guide seal needle valve for a high pressure fuel injector according to claim 1, characterized in that the textured surface is an array of surface textures machined into the surface of the needle valve guide portion (2).

3. The surface texture guide seal needle valve for a high pressure fuel injector of claim 2, characterized in that the shape of the surface texture is circular, diamond, square or oval.

4. The surface texture pilot seal needle valve for a high pressure fuel injector of claim 2, characterized by a surface texture unit area occupancy S of each surface texture_pLess than 0.2.

5. The surface texture pilot seal needle valve for a high pressure fuel injector of claim 4, characterized by a unit area occupancy

L₁Is the center-to-center distance of the adjacent surface texture.

6. A surface texture guide seal needle valve for a high pressure fuel injector according to any one of claims 1 to 5, characterized in that the surface texture of the needle valve guide part (2) is processed in an array by laser processing.

7. The surface texture guide sealing needle valve for the high-pressure fuel injector is characterized in that the needle valve body (1) and the needle valve guide part (2) are in clearance fit, and the clearance delta is kept between 1 and 5 microns.