Cylinder sleeve for novel fuel and machining process for inner surface of cylinder sleeve

Abstract

The invention relates to the technical field of cylinder sleeves adopting novel fuel, in particular to a cylinder sleeve for novel fuel, and the inner surface of the cylinder sleeve is provided with a chromium coating. High-density scribed lines are etched on the inner surface of the air cylinder sleeve and close to a piston reversing area of the air cylinder cover; low-density scribed lines are etched on the inner surface of the air cylinder sleeve and the piston ring operation position except a piston reversing area. The high-density scribed lines and the low-density scribed lines are respectively etched on the chromium-plated layer on the inner surface of the cylinder sleeve, so that the problem of corrosive wear caused by novel fuels such as methanol and hydrogen can be effectively resisted through the chromium-plated layer. Meanwhile, the lubricating performance of the inner surface of the cylinder sleeve is guaranteed through the scribed lines.

Description

Technical Field

[0001] The present invention relates to the technical field of cylinder liners using new fuels. The new fuels are methanol fuel and hydrogen fuel. Specifically, the present invention relates to a cylinder liner for new fuels and a processing technology for the inner surface of the cylinder liner. Background Art

[0002] With the urgent demand for clean energy due to global climate change, methanol fuel and hydrogen energy, as new transportation fuel options, have attracted much attention. After the engine uses new fuels such as methanol and hydrogen fuel, the combustion products contain a large amount of water, formic acid, formaldehyde and other products. On the one hand, it will cause corrosive wear on the surface of the cylinder liner. On the other hand, when the water cannot be completely discharged, it will cause oil emulsification, affecting the lubrication effect, and further accelerating the wear of the cylinder liner surface.

[0003] In order to solve the above problems of corrosive wear on the surface of the cylinder liner and oil emulsification caused by the incomplete discharge of water. In the prior art, the patent document with the publication number: CN216111036U discloses a piston ring and a methanol engine. This solution provides a new piston ring, in which a first compression ring, a second compression ring and a combined oil ring are arranged in sequence on the piston ring along the direction pointing to the cylinder block. Among them, the second compression ring is changed from the original nose-shaped ring to a positive twist structure with a chamfer on the inner side of the upper end surface, so as to reduce the leakage channel on the outer circumferential surface of the second compression ring, and achieve: reducing the piston air leakage, effectively controlling the oil consumption by using the twisted state of the ring during operation, thereby improving the lubrication effect of the oil and the performance of the closed crankcase ventilation system. However, the above prior art cannot realize the oil distribution work of the cylinder liner, resulting in poor uniformity of the oil film on the cylinder wall. The blowing of the in-cylinder gas and the scouring of the unatomized fuel will thin the local oil film of the cylinder liner, causing problems of in-cylinder wear.

[0004] In order to solve the problem of corrosive wear on the surface of the cylinder liner caused by the application of new fuels such as methanol and hydrogen to the engine. It is necessary to re-enable the surface treatment process of chromium plating, which is wear-resistant and corrosion-resistant, so as to improve the oil consumption and emission problems. However, due to the high hardness of the coating in the prior art hard chromium plating process, it is difficult to process and reliable reticulations cannot be formed on the surface. Therefore, in the prior art, loose chromium plating is adopted on the inner surface of the cylinder liner to form the above reticulations. However, the grooves on the loose chromium plating surface are connected to each other and arranged irregularly, which will lead to uncontrollable oil consumption and excessive emissions. And the intersecting crack grooves will also reduce the strength of the coating, and then lead to phenomena such as coating cracking and peeling, causing the problem of aggravated local wear of the cylinder liner.

[0005] Therefore, those skilled in the art need a new cylinder liner and a processing technology for the inner surface of the cylinder liner, so as to achieve the purpose of ensuring the lubrication performance of the inner surface of the cylinder liner while resisting corrosion and wear caused by new fuels such as methanol and hydrogen, and realizing controllable oil consumption and emissions. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is that the cylinder liner for new fuels cannot ensure the lubrication performance of the inner surface of the cylinder liner while resisting corrosion and wear caused by new fuels such as methanol and hydrogen. For this reason, the present invention provides a cylinder liner for new fuels, the inner surface of the cylinder liner has a chromium plating layer; high-density engraved lines are etched at the position of the piston commutation area close to the cylinder head on the inner surface of the cylinder liner; low-density engraved lines are etched at the piston ring running positions other than the piston commutation area on the inner surface of the cylinder liner.

[0007] Optionally, the material of the cylinder liner is gray cast iron; a copper plating layer and the chromium plating layer are sequentially arranged on the inner surface of the gray cast iron cylinder liner from the inside to the outside, and the high-density engraved lines and the low-density engraved lines are arranged on the chromium plating layer; or,

[0008] The material of the cylinder liner is steel; the inner surface of the steel liner is provided with the chromium plating layer, and the high-density engraved lines and the low-density engraved lines are arranged on the chromium plating layer.

[0009] Optionally, the density range value of the high-density engraved lines is: 20 lines / cm 2 to 35 lines / cm 2 ; the density range value of the low-density engraved lines is: 5 lines / cm 2 to 20 lines / cm 2 ;

[0010] The width of all density engraved lines is 0.05 mm.

[0011] Optionally, the high-density engraved lines and the low-density engraved lines form engraved lines in a mixed pitch form;

[0012] The engraved line length of the high-density engraved lines is 3 mm, the circumferential pitch of the engraved lines is 2 mm, and the axial pitch of the engraved lines is 1 mm; the engraved line length L of the low-density engraved lines is 3 mm, the circumferential pitch D1 of the engraved lines is 2 mm, and the axial pitch D2 of the engraved lines is 3 mm.

[0013] Optionally, in the inner surface of the cylinder liner, the interval with a depth range of 8 mm to 50 mm from the top position close to the cylinder head is the high-density engraved lines;

[0014] In the inner surface of the cylinder liner, the interval from a depth of 50 mm from the top of the cylinder liner to a height value of 30 mm from the bottom of the cylinder liner is the low-density engraved lines.

[0015] Optionally, the high-density engraved lines and the low-density engraved lines are formed by performing texturing before electroplating the chromium plating layer and performing engraving operations after electroplating the chromium plating layer.

[0016] Optionally, the coating thickness of the chromium plating layer is ≥ 40 μm, and the coating hardness of the chromium plating layer is ≥ 750 HV; and / or,

[0017] The roughness Rz of the cylinder liner before engraving is ≤ 5 μm; the inner hole roughness Rpk of the cylinder liner after engraving and polishing is ≤ 0.25 μm; and / or,

[0018] The engraved depth of the inner surface of the cylinder liner is 6 μm to 12 μm.

[0019] Optionally, the material of the cylinder liner is steel, and the steel liner is No. 45 steel to improve the machining performance of the material and prevent deformation during the material processing.

[0020] An inner surface processing process of a cylinder liner, when used for processing a cylinder liner made of steel material, includes the following steps:

[0021] Step S1, cutting the material and performing rough machining on the steel to form a cylinder liner;

[0022] Step S2, performing semi-finishing machining on the cylinder liner and performing fine honing on the inner hole of the cylinder liner;

[0023] Step S3, performing chromium plating treatment on the inner cavity wall of the cylinder liner to form a chromium plating layer; ensuring that the coating thickness of the chromium plating layer is ≥ 40 μm and the coating hardness of the chromium plating layer is ≥ 750 HV;

[0024] Step S4, performing dehydrogenation treatment and inner hole polishing treatment on the cylinder liner respectively to remove residues and impurities on the surface of the cylinder liner;

[0025] Step S5, performing precision turning of the outer circle and precision honing of the inner hole on the cylinder liner respectively;

[0026] Step S6, performing laser engraving on the chromium plating layer of the cylinder liner; forming high-density engraved lines at the piston commutation area position of the cylinder liner, and forming low-density engraved lines at the piston ring operating area position of the cylinder liner except the piston commutation area;

[0027] Step S7, performing polishing treatment on the cylinder liner.

[0028] An inner surface processing process of a cylinder liner, when used for processing a cylinder liner made of gray cast iron material, includes the following steps:

[0029] Step S1, cutting the material and performing rough machining on the gray cast iron material to form a cylinder liner;

[0030] Step S2, semi-finish machining the cylinder liner and finish honing the inner hole of the cylinder liner;

[0031] Step S3, the cylinder liner is successively subjected to copper electroplating treatment, water washing treatment and chromium plating treatment to form a chromium plating layer on the surface of the copper plating layer; ensuring that the coating thickness of the chromium plating layer ≥ 40μm and the coating hardness of the chromium plating layer ≥ 750HV;

[0032] Step S4, perform dehydrogenation treatment and inner hole polishing treatment on the cylinder liner respectively to remove residues and impurities on the surface of the cylinder liner;

[0033] Step S5, perform finish turning the outer circle treatment and finish honing the inner hole treatment on the cylinder liner respectively;

[0034] Step S6, perform laser engraving on the chromium plating layer of the cylinder liner; form high-density engraved lines at the piston commutation area position near the cylinder head on the inner surface of the cylinder liner, and form low-density engraved lines at the piston ring running area position on the inner surface of the cylinder liner except for the piston commutation area;

[0035] Step S7, perform polishing treatment on the cylinder liner.

[0036] The technical solution of the present invention has the following advantages:

[0037] 1. The cylinder liner for a new fuel provided by the present invention has a chromium plating layer on its inner surface; high-density engraved lines are etched at the piston commutation area position near the cylinder head on the inner surface of the cylinder liner; low-density engraved lines are etched at the piston ring running position on the inner surface of the cylinder liner except for the piston commutation area.

[0038] In the present invention, in order to solve the problem of corrosion and wear on the surface of the cylinder liner caused by the use of new fuels such as methanol and hydrogen, it is necessary to chrome-plate the inner surface of the cylinder liner, so as to effectively resist the corrosion and wear problems caused by new fuels such as methanol through the chrome-plated layer. Further, due to the hard chromium plating process, it is difficult to process because of the high hardness of the coating, and it is impossible to form a reliable reticulation on the surface, resulting in the connection of the grooves on the surface of the porous chromium plating in the prior art, showing an irregular arrangement, which will lead to uncontrollable oil consumption and excessive emissions. In order to solve the above problems of uncontrollable oil consumption and excessive emissions, the present invention performs zoned laser etching on the inner surface of the cylinder liner. High-density line etching is carried out at the upper end of the cylinder liner, in the piston commutation area close to the cylinder head. Low-density line etching is carried out in the middle and lower parts of the cylinder liner, at the piston ring running position except the piston commutation area. Since the lubrication requirements in the piston commutation area are higher, high-density lines are needed to improve the lubricating oil storage capacity of the cylinder liner. In addition, since the lubrication is better at the piston ring running position except the piston commutation area, low-density lines are used. The above-mentioned high-density lines and low-density lines etched on the surface of the chrome-plated layer can effectively resist the corrosion problems caused by new fuels, and at the same time reduce friction, so as to achieve controllable oil consumption and emissions.

[0039] 2. The cylinder liner for new fuels provided by the present invention, the material of the cylinder liner is gray cast iron; a copper plating layer and the chrome-plated layer are sequentially arranged on the inner surface of the gray cast iron cylinder liner from the inside to the outside, and the high-density lines and the low-density lines are arranged on the chrome-plated layer.

[0040] When the material of the cylinder liner is gray cast iron, in the present invention, copper plating is used as a primer on the gray cast iron surface, and then chrome plating is carried out. The above method can effectively improve the bonding strength between the chrome-plated layer and the gray cast iron cylinder liner. In addition, when the material of the cylinder liner is steel, the steel cylinder liner can be directly chrome-plated without priming.

[0041] 3. The cylinder liner for new fuels provided by the present invention, the high-density lines and the low-density lines form a mixed pitch form of lines;

[0042] The length of the high-density lines is 3 mm, the circumferential pitch of the lines is 2 mm, and the axial pitch of the lines is 1 mm; the length L of the low-density lines is 3 mm, the circumferential pitch D1 of the lines is 2 mm, and the axial pitch D2 of the lines is 3 mm;

[0043] In the present invention, by setting the specific parameters of the high-density lines and the low-density lines as above, the high lubrication requirements in the piston commutation area where the high-density lines are located can be effectively ensured. At the same time, the relatively low lubrication requirements at the piston ring running position where the low-density lines are located are ensured.

[0044] 4. The cylinder liner for the new fuel provided by the present invention has a chromium plating layer with a plating thickness ≥ 40 μm and a plating hardness ≥ 750 HV. The chromium plating layer in the present invention has good wear resistance, with a hardness of 750 HV, enabling it to resist friction loss when the chromium plating layer moves and rubs against other components. Moreover, the combination of the high-density engraved lines and low-density engraved lines effectively reduces the friction coefficient of the cylinder liner, helping to reduce wear and lower oil consumption.

[0045] 5. The cylinder liner for the new fuel provided by the present invention is made of steel, and the steel liner is No. 45 steel to improve the machining performance of the material and prevent deformation during the machining process.

[0046] The steel cylinder liner in the prior art is a thin-walled cylinder liner that needs to be restored after being pressed into the cylinder block. Therefore, the cylinder liner material requires a certain amount of toughness. At the same time, due to the low hardness of the steel material, it is not wear-resistant. Therefore, the cylinder liner in the prior art is chromium-plated, and its main purpose is to increase the wear resistance of the cylinder liner.

[0047] In the present invention, however, the technical problems to be solved by the chromium plating treatment are completely different from those in the prior art. First of all, the chromium plating layer adopted in the present invention is a dense metal plating layer. In an organic acid environment, due to the relatively stable chemical properties of chromium, a passivation film can be formed, which can prevent the acid from eroding the plating layer, isolate the acid from the base metal, and effectively solve the corrosion problem of the new fuel, thus playing a protective role. Further, the material of the cylinder liner in the present invention is No. 45 steel, which can effectively improve the machining performance of the material and reduce the deformation caused by the material, thus facilitating the laser etching work on the surface of the chromium plating layer.

[0048] 6. The inner surface processing technology of the cylinder liner provided by the present invention, when processing a cylinder liner made of steel material, forms high-density engraved lines at the piston commutation area position of the cylinder liner by means of laser engraving, and forms low-density engraved lines at the piston ring running area position of the cylinder liner except the piston commutation area. In the present invention, by forming a corrosion-resistant chromium plating layer on the inner surface of the cylinder liner and performing laser engraving after honing the cylinder liner with the chromium plating layer, regularly arranged engraved lines can be formed.

[0049] 7. The inner surface processing technology of the cylinder liner provided by the present invention, when processing a cylinder liner made of gray cast iron, first performs electroplating copper treatment on the cylinder liner before chromium plating treatment, thereby forming a copper plating layer. The above copper plating layer can improve the bonding strength between the chromium plating layer and gray cast iron and ensure the structural strength of the cylinder liner. Description of the Drawings

[0050] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0051] Figure 1 Schematic diagram of the internal structure of the cylinder liner provided by the present invention;

[0052] Figure 2 Relative schematic diagram of the high-density lines and low-density lines at the inner wall position of the cylinder liner provided by the present invention;

[0053] Figure 3 Relative position schematic diagram of the line length L, the circumferential line spacing D1, and the axial line spacing D2 of the lines at the inner cavity wall position of the cylinder liner provided by the present invention.

[0054] Explanation of the reference numerals:

[0055] 1 - cylinder liner; 2 - chromium plating layer; 3 - high-density lines; 4 - low-density lines. Specific embodiments

[0056] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the drawings. Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0057] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0058] Embodiment 1

[0059] Refer to Figure 1 and Figure 2 , Figure 1 which show the schematic diagram of the internal structure of the cylinder liner in the embodiment of the present invention. Figure 2 which show the relative schematic diagram of the high-density lines and low-density lines at the inner wall position of the cylinder liner in the embodiment of the present invention.

[0060] The cylinder liner 1 provided by the present invention is used for new fuels such as methanol and hydrogen. The material of the cylinder liner 1 is steel; a chromium plating layer 2 is provided on the inner surface of the steel liner. As Figure 2 shown, high-density engraved lines 3 are etched on the inner surface of the cylinder liner 1, at the position of the piston commutation area close to the cylinder head; low-density engraved lines 4 are etched on the inner surface of the cylinder liner 1, at the piston ring running position except the piston commutation area. The chromium plating layer 2 used in the present invention is a dense metal plating layer. In an organic acid environment, due to the relatively stable chemical properties of chromium, a passivation film can be formed, which can prevent the acid from eroding the plating layer, isolate the acid from the base metal, effectively solve the corrosion problem of new fuels, and thus play a protective role.

[0061] Specifically, in this embodiment, considering that the texture of the honing mesh pattern of the cylinder liner in the prior art adopts a uniform distribution structure. The smooth mesh pattern in the prior art will cause insufficient oil storage. When the mesh pattern is too deep, the lubricating oil will be extruded along the grooves, reducing the lubrication effect. The problems of insufficient oil storage in the mesh pattern and the extrusion of the lubricating oil along the grooves will both cause large wear between the cylinder liner and the piston and poor wear resistance of the cylinder liner, not only reducing the service life of the cylinder liner, but also further increasing the fuel consumption. At the same time, because the chromium plating layer 2 obtained by electroplating on the inner surface of the cylinder liner has a high hardness, it leads to the problem of difficult processing. The above high-density engraved lines 3 and low-density engraved lines 4 in the present invention are obtained by performing mesh pattern processing before electroplating the chromium plating layer 2 and performing engraving operations after electroplating the chromium plating layer 2, so as to obtain a surface texture with excellent corrosion resistance, friction reduction and good lubrication.

[0062] Specifically, in a further preferably embodiment, considering that the upper part of the cylinder liner 1 bears a large pressure, and the flushing and dilution of the fresh air and methanol fuel on the lubricating oil will exacerbate the deterioration of the conditions in the upper part of the inner cavity of the cylinder liner 1, making it difficult to form and maintain the lubricating oil film in the upper part of the cylinder. Therefore, in the present invention, high-density engraved lines 3 with high density and relatively large depth are required to improve the lubricating oil storage capacity of the cylinder liner 1. And the lubrication at the piston ring running position except the piston commutation area is better, so low-density engraved lines 4 with low density and small depth are used. The above high-density engraved lines 3 and low-density engraved lines 4 etched on the surface of the chromium plating layer 2 can effectively resist the corrosion problem caused by new fuels, and at the same time reduce friction, so as to achieve controllable engine oil consumption and emissions.

[0063] In the present invention, the influence of the surface roughness of the inner cavity of the cylinder liner 1 on oil storage is considered. Since it is measured that the inner hole roughness of the workpiece after scribing and polishing is ≤0.25 μm, the inner cavity of the cylinder liner 1 is approximately a smooth surface. When the crank angle is 0°, the oil film thickness in the initial state is greater than 3 μm, and the maximum oil film thickness during the traveling process is approximately 7 μm. It is measured that: as the excess oil in the upper working area is scraped downwards, the minimum oil film thickness in the smooth transition area of the cylinder liner is about 2.3 μm to 4.7 μm; the minimum oil film thickness at the top dead center during the entire stroke cycle is less than 1 μm. Because in the functional oil storage area of the present invention, that is, the high-density scribing 3 area, the flushing and dilution of fresh air and methanol fuel also need to be considered, in the present invention, the average oil film thickness of this area is set to 3 μm to 8 μm, so that the lubricating oil scraped off during the downward movement of the piston can reach a maximum average oil film thickness of 2 μm to 7 μm. In addition, the average oil film thickness of the initial smooth transition area, that is, the low-density scribing 4 area, is set to 0.3 μm to 2.7 μm.

[0064] For the above reasons, as Figure 3 shown, the density range value of the high-density scribing 3 is: 20 lines / cm 2 to 35 lines / cm 2 ; the density range value of the low-density scribing 4 is: 5 lines / cm 2 to 20 lines / cm 2 ; the width of all density scribings is 0.05 mm. And, the high-density scribing 3 and the low-density scribing 4 form a mixed pitch form scribing; as Figure 3 shown, the scribing length of the high-density scribing 3 is 3 mm, the circumferential pitch of the scribings is 2 mm, and the axial pitch of the scribings is 1 mm; the scribing length L of the low-density scribing 4 is 3 mm, the circumferential pitch D1 of the scribings is 2 mm, and the axial pitch D2 of the scribings is 3 mm. Moreover, in the inner surface of the cylinder liner 1, in the interval with a depth range of 8 mm to 50 mm from the top position close to the cylinder head is the high-density scribing 3; in the inner surface of the cylinder liner 1, in the interval with a depth of 50 mm from the top of the cylinder liner 1 to a height value of 30 mm from the bottom position of the cylinder liner 1 is the low-density scribing 4. In order to ensure that the chromium plating layer 2 effectively resists frictional wear, in the present invention, the chromium plating layer 2 has a plating thickness of 40 μm, and the plating hardness of the chromium plating layer 2 is 750 HV.

[0065] In addition, the material of the cylinder liner 1 in this embodiment is 45 steel. 45# steel can effectively improve the machining performance of the material, reduce the deformation caused by the material, and thus facilitate the laser scribing work on the surface of the chromium plating layer 2.

[0066] Of course, in this embodiment, there are no specific limitations on the mixed pitch form of the high-density lines 3 and the low-density lines 4, and there are no specific limitations on the line length, the circumferential line pitch, and the axial line pitch. In other embodiments, the densities of the high-density lines 3 and the low-density lines 4 can be adjusted separately as needed.

[0067] Of course, in this embodiment, there are no specific limitations on the coating thickness and the coating hardness of the chromium plating layer 2. In other embodiments, the coating thickness of the chromium plating layer 2 is greater than 40 μm, and the coating hardness of the chromium plating layer 2 is greater than 750 HV.

[0068] Of course, in this embodiment, there is no specific limitation on whether the material of the cylinder liner 1 is selected as 45 steel. In other embodiments, other types of steel can also be selected for the cylinder liner 1 as needed.

[0069] Of course, in this embodiment, there are no specific limitations on the coverage ranges of the high-density lines 3 and the low-density lines 4 on the inner surface of the cylinder liner 1. In other embodiments, the coverage ranges of the high-density lines 3 and the low-density lines 4 of the chromium plating layer 2 can be adjusted arbitrarily as needed.

[0070] An inner surface processing process of a cylinder liner, when used for processing a cylinder liner 1 made of steel material, includes the following steps:

[0071] Step S1, cutting the material and rough machining the steel to form the cylinder liner 1;

[0072] Step S2, semi-finishing the cylinder liner 1 and precision honing the inner hole of the cylinder liner 1;

[0073] Step S3, performing chromium plating treatment on the inner cavity wall of the cylinder liner 1 to form a chromium plating layer 2; ensuring that the coating thickness of the chromium plating layer 2 ≥ 40 μm, and the coating hardness of the chromium plating layer 2 ≥ 750 HV;

[0074] Step S4, performing dehydrogenation treatment and inner hole polishing treatment on the cylinder liner 1 respectively to remove the residues and impurities on the surface of the cylinder liner 1;

[0075] Step S5, performing precision turning of the outer circle and precision honing of the inner hole on the cylinder liner 1 respectively;

[0076] Step S6, performing laser engraving on the chromium plating layer 2 of the cylinder liner 1; forming high-density lines 3 at the piston commutation area position of the cylinder liner 1, and forming low-density lines 4 at the piston ring running area position of the cylinder liner 1 except for the piston commutation area;

[0077] Step S7, performing polishing treatment on the cylinder liner 1.

[0078] Embodiment 2

[0079] Refer toFigure 1 and Figure 2 , Figure 1 shows a schematic diagram of the internal structure of a cylinder liner in an embodiment of the present invention. Figure 2 shows a relative schematic diagram of high-density engraved lines and low-density engraved lines at the inner wall position of the cylinder liner in an embodiment of the present invention.

[0080] The cylinder liner provided by the present invention is used for new fuels such as methanol and hydrogen. The material of the cylinder liner 1 is gray cast iron; a copper plating layer and the chromium plating layer 2 are sequentially arranged on the inner surface of the gray cast iron cylinder liner from the inside to the outside, and the high-density engraved lines 3 and the low-density engraved lines 4 are arranged on the chromium plating layer 2. In the present invention, before the chromium plating treatment of the cylinder liner 1, the cylinder liner 1 is first subjected to electroplating copper treatment to form a copper plating layer. The above copper plating layer can improve the bonding strength between the chromium plating layer 2 and the gray cast iron and ensure the structural strength of the cylinder liner 1.

[0081] As Figure 2 shown, high-density engraved lines 3 are etched at the inner surface of the cylinder liner 1, at the position of the piston commutation area close to the cylinder head; low-density engraved lines 4 are etched at the inner surface of the cylinder liner 1, at the piston ring running position except the piston commutation area.

[0082] Specifically, in this embodiment, considering that the texture of the honing mesh pattern of the cylinder liner in the prior art adopts a uniform distribution structure. The smooth mesh pattern in the prior art will cause insufficient oil storage. When the mesh pattern is too deep, the lubricating oil will be extruded along the grooves, reducing the lubrication effect. The problems of insufficient oil storage in the mesh and the extrusion of the lubricating oil along the grooves will both cause large wear between the cylinder liner and the piston and poor wear resistance of the cylinder liner, not only reducing the service life of the cylinder liner, but also further increasing the fuel consumption. At the same time, because the chromium plating layer 2 obtained by electroplating on the inner surface of the cylinder liner has a high hardness, it causes a problem of large processing difficulty. The above high-density engraved lines 3 and low-density engraved lines 4 in the present invention obtain excellent corrosion resistance, anti-friction, and well-lubricated surface textures by performing mesh processing before electroplating the chromium plating layer 2 and performing engraving operations after electroplating the chromium plating layer 2.

[0083] Specifically, in a further preferred embodiment, considering that the upper part of the cylinder liner 1 bears a large pressure, the flushing and dilution of the fresh air and methanol fuel to the lubricating oil will exacerbate the deterioration of the conditions at the upper part of the inner cavity of the cylinder liner 1, making it difficult to form and maintain the lubricating oil film at the upper part of the cylinder. Therefore, in the present invention, high-density engraved lines 3 with high density and relatively large depth are required to improve the lubricating oil storage capacity of the cylinder liner 1. And the lubrication at the piston ring running position except the piston commutation area is better, so low-density engraved lines 4 with low density and small depth are adopted. The above high-density engraved lines 3 and low-density engraved lines 4 etched on the surface of the chromium plating layer 2 can effectively resist the corrosion problem caused by the new fuel, and at the same time reduce friction, so as to achieve controllable engine oil consumption and emissions.

[0084] In the present invention, the influence of the surface roughness of the inner cavity of the cylinder liner 1 on oil storage is considered. Since it is measured that the inner hole roughness of the workpiece after scribing and polishing is ≤ 0.25 μm, the inner cavity of the cylinder liner 1 is an approximately smooth surface. When the crank angle is 0°, the oil film thickness in the initial state is greater than 3 μm, and the maximum oil film thickness during the traveling process is about 7 μm. It is measured that: as the excess oil in the upper working area is scraped downwards, the minimum oil film thickness in the smooth transition area of the cylinder liner is about 2.3 μm to 4.7 μm; the minimum oil film thickness at the top dead center during the entire stroke cycle is less than 1 μm. Because in the functional oil storage area in the present invention, that is, the high-density scribing 3 area, the flushing and dilution of fresh air and methanol fuel also need to be considered, the average oil film thickness in this area is set to 3 μm to 8 μm in the present invention, so that the lubricating oil scraped off during the downward movement of the piston can reach a maximum average oil film thickness of 2 μm to 7 μm. In addition, the average oil film thickness of the initial smooth transition area, that is, the low-density scribing 4 area, is set to 0.3 μm to 2.7 μm.

[0085] For the above reasons, as Figure 3 shown, the density range value of the high-density scribing 3 is: 20 lines / cm 2 to 35 lines / cm 2 ; the density range value of the low-density scribing 4 is: 5 lines / cm 2 to 20 lines / cm 2 ; the width of all density scribings is 0.05 mm. And, the high-density scribing 3 and the low-density scribing 4 form a mixed pitch form scribing; as Figure 3 shown, the scribing length of the high-density scribing 3 is 3 mm, the circumferential scribing pitch is 2 mm, and the axial scribing pitch is 1 mm; the scribing length L of the low-density scribing 4 is 3 mm, the circumferential scribing pitch D1 is 2 mm, and the axial scribing pitch D2 is 3 mm. Moreover, in the inner surface of the cylinder liner 1, in the interval with a depth range of 8 mm to 50 mm from the top position close to the cylinder head is the high-density scribing 3; in the inner surface of the cylinder liner 1, in the interval from a depth of 50 mm from the top of the cylinder liner 1 to a height value of 30 mm from the bottom of the cylinder liner 1 is the low-density scribing 4. In order to ensure that the chromium plating layer 2 effectively resists frictional wear, in the present invention, the plating thickness of the chromium plating layer 2 is 40 μm, and the plating hardness of the chromium plating layer 2 is 750 HV.

[0086] An inner surface processing process of a cylinder liner, when processing a cylinder liner 1 made of gray cast iron, includes the following steps:

[0087] Step S1, cutting the material and rough machining the gray cast iron material to form the cylinder liner 1;

[0088] Step S2, semi-finish machining the cylinder liner 1 and precisely honing the inner hole of the cylinder liner 1;

[0089] Step S3, the cylinder liner 1 is successively subjected to copper electroplating treatment, water washing treatment and chromium plating treatment to form a chromium plating layer 2 on the surface of the copper plating layer; ensuring that the coating thickness of the chromium plating layer 2 ≥ 40 μm and the coating hardness of the chromium plating layer 2 ≥ 750 HV;

[0090] Step S4, dehydrogenation treatment and inner hole polishing treatment are respectively carried out on the cylinder liner 1 to remove residues and impurities on the surface of the cylinder liner 1;

[0091] Step S5, finish turning the outer circle of the cylinder liner 1 and precisely honing the inner hole;

[0092] Step S6, laser engraving the chromium plating layer 2 of the cylinder liner 1; forming high-density engraved lines 3 at the piston commutation area position of the cylinder liner 1 and forming low-density engraved lines 4 at the piston ring running area position of the cylinder liner 1 except the piston commutation area;

[0093] Step S7, polishing the cylinder liner 1.

[0094] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or alterations can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or alterations derived therefrom are still within the protection scope of the present invention.

Claims

1. A cylinder liner for a new type of fuel, characterized in that, The inner surface of the cylinder liner (1) has a chromium plating layer (2); high-density engraved lines (3) are etched on the inner surface of the cylinder liner (1) at the position of the piston commutation area near the cylinder head; low-density engraved lines (4) are etched on the inner surface of the cylinder liner (1) at the piston ring running positions except the piston commutation area.

2. The cylinder liner for a new fuel according to claim 1, characterized in that, The material of the cylinder liner (1) is gray cast iron; a copper plating layer and the chromium plating layer (2) are sequentially arranged on the inner surface of the gray cast iron cylinder liner from the inside to the outside, and the high-density engraved lines (3) and the low-density engraved lines (4) are arranged on the chromium plating layer (2); or, The material of the cylinder liner (1) is steel; the chromium plating layer (2) is arranged on the inner surface of the steel liner, and the high-density engraved lines (3) and the low-density engraved lines (4) are arranged on the chromium plating layer (2).

3. The cylinder liner for a new fuel according to claim 1 or 2, characterized in that, The density range value of the high-density engraved lines (3) is: 20 lines / cm 2 to 35 lines / cm 2 ; The density range value of the low-density engraved lines (4) is: 5 lines / cm 2 to 20 lines / cm 2 ; The width of all density engraved lines is 0.05 mm.

4. The cylinder liner for a new fuel according to claim 3, characterized in that, The high-density engraved lines (3) and the low-density engraved lines (4) form engraved lines in a mixed pitch form; The engraved line length of the high-density engraved lines (3) is 3 mm, the circumferential pitch of the engraved lines is 2 mm, and the axial pitch of the engraved lines is 1 mm; the engraved line length L of the low-density engraved lines (4) is 3 mm, the circumferential pitch D1 of the engraved lines is 2 mm, and the axial pitch D2 of the engraved lines is 3 mm.

5. The cylinder liner for a new fuel according to claim 4, characterized in that, In the inner surface of the cylinder liner (1), the interval with a depth range of 8 mm to 50 mm from the top position near the cylinder head is the high-density engraved lines (3); In the inner surface of the cylinder liner (1), the interval from the depth of 50 mm from the top of the cylinder liner (1) to the height value of 30 mm from the bottom of the cylinder liner (1) is the low-density engraved lines (4).

6. The cylinder liner for a new fuel according to any one of claims 3 to 5, characterized in that, The high-density engraved lines (3) and the low-density engraved lines (4) are formed by performing reticulation processing before electroplating the chromium plating layer (2) and performing engraved line operations after electroplating the chromium plating layer (2).

7. The cylinder liner for a new fuel according to claim 1 or 2, characterized in that, The coating thickness of the chromium plating layer (2) ≥ 40 μm, and the coating hardness of the chromium plating layer (2) ≥ 750 HV; and / or, The surface roughness Rz of the cylinder liner (1) before engraving ≤ 5 μm; the inner hole surface roughness Rpk of the cylinder liner (1) after engraving and polishing ≤ 0.25 μm; and / or, The engraved line depth on the inner surface of the cylinder liner (1) is 6 μm to 12 μm.

8. The cylinder liner for a new fuel according to claim 2, characterized in that, The material of the cylinder liner (1) is steel, and the steel liner is 45 steel to improve the machining performance of the material and prevent deformation during the material processing.

9. A machining process for the inner surface of a cylinder liner, characterized in that, When machining the cylinder liner (1) made of steel material, the following steps are included: Step S1, cutting the material and performing rough machining on the steel to form the cylinder liner (1); Step S2, performing semi-finishing machining on the cylinder liner (1) and performing fine honing on the inner hole of the cylinder liner (1); Step S3, performing chromium plating treatment on the inner cavity wall of the cylinder liner (1) to form the chromium plating layer (2); ensuring that the coating thickness of the chromium plating layer (2) ≥ 40 μm and the coating hardness of the chromium plating layer (2) ≥ 750 HV; Step S4, performing dehydrogenation treatment and inner hole polishing treatment on the cylinder liner (1) respectively to remove the residues and impurities on the surface of the cylinder liner (1); Step S5, performing fine turning on the outer circle of the cylinder liner (1) and fine honing on the inner hole of the cylinder liner (1) respectively; Step S6, laser engrave the chromium plating layer (2) of the cylinder liner (1); form high-density engraved lines (3) at the piston commutation area position of the cylinder liner (1), and form low-density engraved lines (4) at the piston ring running area position of the cylinder liner (1) except for the piston commutation area; Step S7, perform a polishing treatment on the cylinder liner (1).

10. A machining process for the inner surface of a cylinder liner, characterized in that, When machining a cylinder liner (1) made of gray cast iron, the following steps are included: Step S1, cut the material and perform rough machining on the gray cast iron material to form the cylinder liner (1); Step S2, perform semi-finishing on the cylinder liner (1) and perform fine honing on the inner hole of the cylinder liner (1); Step S3, the cylinder liner (1) is successively subjected to electroplating copper treatment, water washing treatment, and chromium plating treatment to form a chromium plating layer (2) on the surface of the copper plating layer; ensure that the plating thickness of the chromium plating layer (2) ≥ 40μm, and the plating hardness of the chromium plating layer (2) ≥ 750HV; Step S4, perform dehydrogenation treatment and inner hole polishing treatment on the cylinder liner (1) respectively to remove residues and impurities on the surface of the cylinder liner (1); Step S5, perform finish turning on the outer circle of the cylinder liner (1) and finish honing on the inner hole respectively; Step S6, laser engrave the chromium plating layer (2) of the cylinder liner (1); form high-density engraved lines (3) at the piston commutation area position of the cylinder liner (1), and form low-density engraved lines (4) at the piston ring running area position of the cylinder liner (1) except for the piston commutation area; Step S7, perform a polishing treatment on the cylinder liner (1).

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