A method for preparing a hydrophobic textured surface of an axial piston pump plunger friction pair and a liner

Abstract

The present invention relates to a method for preparing a plunger friction pair of an axial piston pump and a hydrophobic textured surface of a bushing, wherein the plunger friction pair comprises a plunger friction pair composed of a plunger and a cylinder body, the plunger of the plunger friction pair reciprocates in the bushing of the plunger cavity of the cylinder body, the plunger comprises a plunger body and a plunger ball head, a groove structure is provided on the plunger body, the groove structure is composed of a plurality of grooves I, a bushing groove structure is provided on the inner surface of the bushing, and a hydrophobic microstructure is provided on the inner surface of the bushing and the bushing groove structure. The groove structure in the present invention will reduce the flow of oil through the gap of the plunger pair, thereby reducing the leakage of the plunger pair, and this structure also has a pressure equalization effect, the pressure change amplitude in the plunger pair is very small, the pit-type microstructure surface has super hydrophobicity, and due to its special wetting characteristics, it can change the state of the liquid during the flow process, so the pit-type microstructure surface has the effect of lubrication and drag reduction.

Description

Technical Field

[0001] The invention belongs to the technical field of plunger pumps, and in particular relates to a method for preparing a plunger friction pair and a bushing hydrophobic texture surface in a high power density axial plunger pump having a multi-scale hydrophobic texture surface. Background Art

[0002] Axial piston pumps have the advantages of high rated pressure, compact structure, high efficiency and convenient flow regulation, so they are widely used in various engineering equipment. As one of the three major friction pairs that affect the working performance of the piston pump, the piston pair is composed of the piston and the cylinder body, so the study of the piston pair has practical significance.

[0003] The working principle of the axial piston pump is to rely on the reciprocating motion of the plunger in the bushing of the cylinder plunger cavity to change the volume of the sealed working chamber to achieve oil suction and oil pressure. As the key components of the axial piston pump, the plunger and bushing have a decisive influence on whether the plunger pump can work normally and its life, and are also the difficulties in the design of the plunger pump. Some scholars and technicians have conducted research on the plunger pair, such as the patent "A high wear-resistant plunger" (ZL202220689126.4), the plunger structure is too complicated and difficult to process and produce. The patent "High-pressure seawater axial piston pump plunger friction pair with bionic non-smooth surface" (ZL201410061751.4) requires high-precision special processing equipment, which is costly and difficult to mass produce. The article "Design and finite element analysis of the key part of the high-pressure water pump plunger" optimizes the design and performs finite element analysis on the plunger, mainly comparing the yield force and deformation of plungers of different materials.

[0004] The above patents and papers have not been able to significantly improve the lubrication performance of the plunger pair, and the life extension is not significant. In summary, it is urgent to design a new plunger friction pair structure to solve the above problems. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a method for preparing an axial piston pump plunger friction pair with a hydrophobic texture surface and a bushing hydrophobic texture surface, an axial piston pump plunger friction pair with improved plunger and bushing surface structures, a groove structure that reduces the oil flow through the plunger pair gap, thereby reducing the leakage of the plunger pair, and this structure also has a pressure equalization effect, the pressure change amplitude in the plunger pair is very small, the pit-type microstructure surface is super hydrophobic, and due to its special wetting characteristics, it can change the state of the liquid during the flow process, so the pit-type microstructure surface has the effect of lubrication and drag reduction, and combined use can improve the load-bearing capacity of the axial piston pump plunger pair, improve wear resistance, reduce the friction coefficient of the friction pair, and achieve high power density and long life of the axial piston pump.

[0006] Technical solution: In order to solve the above technical problems, the present invention describes an axial piston pump plunger friction pair with a hydrophobic texture surface, which includes a plunger friction pair composed of a plunger and a cylinder body, the plunger of the plunger friction pair reciprocates in the bushing of the plunger cavity of the cylinder body, the plunger includes a plunger body and a plunger ball head, a groove structure is provided on the plunger body, the groove structure consists of a plurality of grooves I, a bushing groove structure is provided on the inner surface of the bushing, and a hydrophobic microstructure is provided on the inner surface of the bushing and the bushing groove structure.

[0007] Furthermore, the cross-sectional shape of the groove I is a rectangle.

[0008] Furthermore, the width b of the groove I is 2 mm, the depth h is 1 mm, and the spacing between adjacent grooves I is 5 mm.

[0009] Furthermore, the length L2 of the groove structure is 1 / 2 of the length L1 of the plunger, and the number of grooves I on the surface of the plunger body n1= L2 / 7 is an integer.

[0010] Furthermore, the bushing groove structure is composed of a plurality of grooves II, the length of the bushing groove structure is L3, and the number of grooves II on the inner surface of the bushing is n2 = L3 / 7 which is an integer.

[0011] Furthermore, the hydrophobic microstructure is a pit-type microstructure, wherein the pit depth is 6 μm, the pit width is 20 μm, and the spacing between adjacent pits is 4 μm.

[0012] Furthermore, the groove structure and the bushing groove structure have the same size, and grooves I and grooves II are distributed at equal distances.

[0013] A method for preparing a hydrophobic textured surface of a bushing in an axial piston pump plunger friction pair, the method comprising the following steps:

[0014] (1) Use 600 mesh to 2000 mesh SiC The inner surface of the bushing was physically polished with sandpaper, surface stains were washed off with deionized water, and fine particles remaining on the metal surface were removed by ultrasonic cleaning in anhydrous ethanol for 10 minutes using an ultrasonic cleaning instrument;

[0015] (2) Rinse again with deionized water and place the cleaned bushing in a 10% concentration of H 2 SO 4 After soaking in the aqueous solution for 10 seconds, the bushing is taken out and washed with deionized water for the third time, and finally dried for later use;

[0016] (3) The electrolyte solution is 10.04 g / L CuSO 4 ·5H 2 O A mixed solution of 0.05M sulfuric acid solution, with a distance of 2cm between the cathode and cathode, a current of 1A, and an electrochemical deposition time of 60s. During the reaction, bubbles are continuously generated from the cathode copper sheet, and red deposits are obviously seen. After the reaction is completed, the cathode copper sheet is taken out, washed with deionized water, and dried to obtain a pit-type microstructure.

[0017] (4) The obtained concave-shaped microstructure bushing is immersed in anhydrous ethanol solution of octadecyl mercaptan for 10 minutes and then subjected to modification treatment to obtain a super-hydrophobic concave-shaped microstructure surface.

[0018] The plunger in the present invention is an axisymmetric structure with a length L 1 ,diameter D 1 The plunger includes a plunger body and a plunger ball head. The plunger has a plunger hole inside. The plunger hole provides an oil source for static pressure support for the plunger and the sliding shoe to prevent them from wear. Under high power density working conditions, the plunger hole can effectively improve the pressure shock situation.

[0019] The screenshot was taken using an antennae measuring instrument to obtain the form of a water droplet when it fell on the sample surface for 1 second and reached stability. It was found that the contact angle of the water droplet on the microscopic multi-scale pit-textured surface was greater than 150°.

[0020] The pit-shaped microstructure has superhydrophobic properties. Inspired by the "lotus leaf effect", it was discovered that the superhydrophobic phenomenon is caused by the special water-repellent phenomenon on the lotus leaf surface. The superhydrophobic surface can change the state of the liquid during the flow process due to its special wetting properties, especially in the field of microfluidics. Through this special wetting property, the metal surface can perform particularly well in terms of lubrication and drag reduction.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0022] (1) The hydrophobic microstructure can form an air film layer on the inner surface of the bushing, blocking the solid-liquid contact area as much as possible, and allowing more air-liquid contact to achieve the effect of dynamic pressure lubrication and drag reduction;

[0023] (2) Abrasive particles and lubricating oil can be stored in the groove structure and the bushing groove structure space, thereby improving the load-bearing capacity of the axial piston pump piston pair, improving the wear resistance, and reducing the friction coefficient between the friction pairs;

[0024] (3) The flow rate through the gap in the piston pair is small, and the friction pair oil film has a good pressure equalization effect, which can reduce wear and achieve high power density and long life of the axial piston pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a front cross-sectional view of the present invention;

[0026] Figure 2 It is a schematic diagram of the external structure of the plunger in the present invention;

[0027] Figure 3 It is a schematic diagram of the dimensions of the plunger in the present invention;

[0028] Figure 4 yes Figure 2 A local enlarged schematic diagram of the middle A;

[0029] Figure 5 is a front cross-sectional view of the bushing in the present invention;

[0030] Figure 6 It is a partial structural schematic diagram of the hydrophobic microstructure in the present invention;

[0031] Figure 7 is a SEM schematic diagram of the hydrophobic texture of the bushing in the present invention;

[0032] Figure 8 Schematic diagram of static contact angle of the hydrophobic texture of the bushing in the present invention;

[0033] Fig. 9 It is a schematic diagram of the spreading state of water droplets on the hydrophobic texture surface of the bushing in the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0035] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 and Fig. 9As shown, the axial piston pump plunger friction pair with a hydrophobic texture surface described in the present invention includes a plunger friction pair consisting of a plunger 1 and a cylinder 2. The plunger 1 of the plunger friction pair reciprocates in a bushing 3 of a plunger cavity of the cylinder 2. The plunger 1 includes a plunger body 4 and a plunger ball head 5. A groove structure is provided on the plunger body 4. The groove structure consists of a plurality of grooves Ⅰ6. The length L2 of the groove structure is 1 / 2 of the length L1 of the plunger 1. The number n1 of the grooves Ⅰ6 on the surface of the plunger body 4 is equal to 1 / 2 of the length L1 of the plunger 1. L2 / 7 is an integer, the cross-sectional shape of the groove Ⅰ6 is a rectangle, the width b of the groove Ⅰ6 is 2 mm, the depth h is 1 mm, the spacing between adjacent grooves Ⅰ6 is 5 mm, a bushing groove structure is provided on the inner surface of the bushing 3, and a hydrophobic microstructure is provided on the inner surfaces of the bushing and the bushing groove structure. The bushing groove structure is composed of a plurality of grooves Ⅱ7, the groove structure is the same size as the bushing groove structure, and grooves Ⅰ6 and grooves Ⅱ7 are equidistantly distributed, the length of the bushing groove structure is L3, the number n2= L3 / 7 of grooves Ⅱ7 on the inner surface of the bushing 3 is an integer, the hydrophobic microstructure is a pit-type microstructure, wherein the depth of pit 8 is 6 μm, the width of pit 8 is 20 μm, and the spacing between adjacent pits 8 is 4 μm.

[0036] A method for preparing a hydrophobic textured surface of a bushing in an axial piston pump plunger friction pair, the method comprising the following steps:

[0037] (1) Use 600 mesh to 2000 mesh SiC The inner surface of the bushing was physically polished with sandpaper, surface stains were washed off with deionized water, and fine particles remaining on the metal surface were removed by ultrasonic cleaning in anhydrous ethanol for 10 minutes using an ultrasonic cleaning instrument;

[0038] (2) Rinse again with deionized water and place the cleaned bushing in a 10% concentration of H 2 SO 4 After soaking in the aqueous solution for 10 seconds, the bushing is taken out and washed with deionized water for the third time, and finally dried for later use;

[0039] (3) The electrolyte solution is 10.04 g / L CuSO 4 ·5H 2 OA mixed solution of 0.05M sulfuric acid solution, with a distance of 2cm between the cathode and cathode, a current of 1A, and an electrochemical deposition time of 60s. During the reaction, bubbles are continuously generated from the cathode copper sheet, and red deposits are obviously seen. After the reaction is completed, the cathode copper sheet is taken out, washed with deionized water, and dried to obtain a pit-type microstructure.

[0040] (4) The obtained concave-shaped microstructure bushing is immersed in anhydrous ethanol solution of octadecyl mercaptan for 10 minutes and then subjected to modification treatment to obtain a super-hydrophobic concave-shaped microstructure surface.

[0041] The hydrophobic microstructure in the present invention can form an air film layer on the inner surface of the bushing, blocking the solid-liquid contact area as much as possible, and more air-liquid contact, so as to achieve the dynamic pressure lubrication and drag reduction effect; abrasive particles and lubricating oil can be stored in the groove structure and the bushing groove structure space, improving the bearing capacity of the axial piston pump plunger pair, improving wear resistance, and reducing the friction coefficient between the friction pairs; the flow rate through the gap in the plunger pair is small, and the friction pair oil film pressure equalization effect is good, which can reduce wear and realize high power density and long life of the axial piston pump.

[0042] The present invention provides a thought and method. There are many methods and ways to implement the technical solution. The above is only the preferred implementation mode of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. An axial piston pump plunger friction pair with a hydrophobic texture surface, comprising a plunger friction pair consisting of a plunger (1) and a cylinder (2), wherein the plunger (1) of the plunger friction pair reciprocates in a bushing (3) of a plunger cavity of the cylinder (2), the plunger (1) comprising a plunger body (4) and a plunger ball head (5), characterized in that: A groove structure is provided on the plunger body (4), the groove structure is composed of a plurality of grooves I (6), a bushing groove structure is provided on the inner surface of the bushing (3), and a hydrophobic microstructure is provided on the inner surface of the bushing and the bushing groove structure; The cross-sectional shape of the groove I (6) is a rectangle; The width b of the groove I (6) is 2 mm, the depth h is 1 mm, and the spacing between adjacent grooves I (6) is 5 mm; The length L2 of the groove structure is 1 / 2 of the length L1 of the plunger (1), and the number n1 of the grooves I (6) on the surface of the plunger body (4) is an integer of L2 / 7; The bushing groove structure is composed of a plurality of grooves II (7), the length of the bushing groove structure is L3, and the number of grooves II (7) on the inner surface of the bushing (3) is n2 = L3 / 7, whichever is greater. The hydrophobic microstructure is a pit-type microstructure, wherein the pit (8) has a depth of 6 μm, a width of 20 μm, and a spacing between adjacent pits (8) of 4 μm; The groove structure has the same size as the bushing groove structure, and the grooves I (6) and the grooves II (7) are distributed at equal distances.

2. A method for preparing a hydrophobic textured surface of a bushing in an axial piston pump plunger friction pair having a hydrophobic textured surface according to claim 1, characterized in that: It includes the following steps, (1) Use 600 mesh to 2000 mesh SiC The inner surface of the bushing was physically polished with sandpaper, surface stains were washed off with deionized water, and fine particles remaining on the metal surface were removed by ultrasonic cleaning in anhydrous ethanol for 10 minutes using an ultrasonic cleaning instrument; (2) Rinse again with deionized water and place the cleaned bushing in a 10% concentration of H 2 SO 4 After soaking in the aqueous solution for 10 seconds, the bushing is taken out and washed with deionized water for the third time, and finally dried for later use; (3) The electrolyte solution is 10.04 g / L CuSO 4 ·5H 2 O A mixed solution of 0.05M sulfuric acid solution, with a distance of 2cm between the cathode and cathode, a current of 1A, and an electrochemical deposition time of 60s. During the reaction, bubbles are continuously generated from the cathode copper sheet, and red deposits are obviously seen. After the reaction is completed, the cathode copper sheet is taken out, washed with deionized water, and dried to obtain a pit-type microstructure. (4) The obtained concave-shaped microstructure bushing is immersed in anhydrous ethanol solution of octadecyl mercaptan for 10 minutes and then subjected to modification treatment to obtain a super-hydrophobic concave-shaped microstructure surface.

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