A crankshaft and a method of manufacturing and using the same

Abstract

This invention belongs to the field of crankshaft technology, and specifically relates to a crankshaft, its manufacturing method, and its applications. The crankshaft of this invention includes a crankshaft body and a composite layer disposed on the surface of the crankshaft body; the composite layer includes a nitrided layer, a phosphate layer, and a lubricating layer arranged sequentially from the inside out. The nitrided layer improves the fatigue strength and wear resistance of the crankshaft. The phosphate layer formed on the nitrided layer serves as a base layer, providing a good adhesion foundation for the lubricating layer and improving the bonding between the phosphate layer and the lubricating layer, i.e., improving the bonding between the lubricating layer and the crankshaft body, allowing the lubricating layer to better perform its function of reducing friction and wear. When the crankshaft-bearing friction pair enters the boundary lubrication state, the lubricating layer is consumed first, forming a solid lubrication transfer film on the bearing surface. This avoids direct contact between the crankshaft's nitrided layer and the bearing, while also achieving a friction-reducing and lubricating effect, thus improving the wear of the crankshaft-bearing friction pair.

Description

Technical Field

[0001] This invention belongs to the field of crankshaft technology, and specifically relates to a crankshaft, its preparation method, and its application. Background Technology

[0002] The crankshaft is one of the core components of a compressor. It converts the rotational motion of an electric motor or engine into reciprocating motion, thereby driving the compressor piston to perform compression. During crankshaft operation, a friction pair is formed between the crankshaft and bearings or rollers, bearing a huge mechanical load. The bearings or rollers support the crankshaft and reduce its frictional resistance, ensuring that the crankshaft can rotate smoothly and transmit power. The crankshaft is subjected to the combined effects of centrifugal force from the rotating mass, periodically changing gas inertial force, and reciprocating inertial force, which subject the crankshaft bearing to bending and torsional loads. Therefore, the crankshaft is required to have sufficient strength and rigidity, and its surface must be wear-resistant.

[0003] Currently, although the wear resistance of crankshafts has been improved to some extent, frictional wear still exists between the crankshaft and bearings or rollers under high-load, high-speed operating environments, accelerating surface wear and severely affecting the service life of the crankshaft. Meanwhile, the trend towards higher speeds and smaller sizes in rotary compressors makes the operating conditions of crankshafts even more demanding. Conventional phosphating treatment is no longer sufficient to prevent abnormal wear between the compressor crankshaft and bearings. Nitriding is a commonly used method to improve the surface hardness and wear resistance of workpieces. Nitriding can introduce a high-hardness nitride white layer onto the crankshaft surface, significantly improving its wear resistance, but it may exacerbate wear on bearings when entering boundary lubrication conditions. CN209637960U proposes introducing a composite diffusion layer consisting of a nitrided layer and an oxide layer on the crankshaft surface to improve its surface hardness and wear resistance. By sequentially performing nitriding and oxidation treatments, a relatively shear-resistant oxide layer can be generated in situ on the nitrided layer surface, enhancing the resistance of the friction pair to sintering under boundary friction conditions. However, the surface oxide layer often has a friction-increasing effect. After the oxide particles in the surface oxide layer detach from the matrix, they may enter the clearance between the crankshaft and the bearing, becoming abrasive particles, increasing frictional losses during crankshaft operation, reducing compressor unit efficiency, and exacerbating bearing wear. Furthermore, the presence of the oxide layer limits the correction of excessive crankshaft runout after nitriding, making it impossible to simultaneously maintain crankshaft dimensional accuracy to meet usage requirements and maintain the oxide layer's enhanced sintering resistance, thus affecting the practical feasibility of this technology. Therefore, there is an urgent need to provide a crankshaft with good wear resistance, which can reduce the wear of the crankshaft-bearing friction pair, ensure the reliability and service life of the crankshaft-bearing friction pair, and thus ensure the reliability and operational performance of the compressor. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art.

[0005] Therefore, a first aspect of the present invention provides a crankshaft.

[0006] Specifically, the crankshaft includes a crankshaft body and a composite layer disposed on the surface of the crankshaft body; the composite layer includes a nitriding layer, a phosphate layer and a lubricating layer disposed sequentially from the inside to the outside.

[0007] Specifically, during compressor operation, the crankshaft rotates at high speed within the bearing bore, resulting in friction with the bearing. Under certain harsh conditions, such as when refrigerant deposits occur in the compressor, a large amount of refrigerant dissolves into the refrigeration oil, causing a decrease in the oil viscosity and a significant reduction in the oil film's carrying capacity. This leads to the crankshaft and bearing friction pair entering a boundary lubrication state, where the crankshaft and bearing substrate come into contact. Due to the extremely high hardness of the nitrided layer on the crankshaft surface, this can cause severe bearing wear. This invention first sets a layer of extremely hard nitride on the crankshaft body surface as a nitriding layer, which can significantly improve the crankshaft's fatigue strength and wear resistance. Then, a phosphate layer and a lubricating layer are sequentially set on the nitrided layer. The phosphate layer formed on the nitrided layer serves as a base layer, providing a good adhesion foundation for the lubricating layer, which helps enhance the adhesion of the lubricating layer and improves the bonding between the phosphate layer and the lubricating layer. This improves the bonding between the lubricating layer and the crankshaft body, reducing lubrication or protective failures caused by interlayer peeling or detachment, allowing the lubricating layer to better perform its function of reducing friction and wear. When the crankshaft-bearing friction pair enters the boundary lubrication state, the lubricating layer is first consumed, forming a solid lubricant transfer film on the bearing surface. This avoids direct contact between the crankshaft's nitride layer and the bearing, while also providing friction reduction and lubrication. Secondly, the presence of the lubricating layer increases the actual contact area between the crankshaft-bearing friction pair, reduces interfacial contact stress, and lowers the risk of the nitride layer cracking due to excessive load. In other words, this invention, by sequentially setting a nitride layer, a phosphate layer, and a lubricating layer on the surface of the crankshaft body, improves the crankshaft's own wear resistance while ensuring lubrication between the crankshaft and bearing friction pairs, reducing the risk of the nitride layer cracking due to excessive load, significantly improving the wear of the crankshaft-bearing friction pair, and significantly reducing the risk of bearing wear.

[0008] According to some embodiments of the present invention, the thickness of the nitrided layer is 4.5-18 μm.

[0009] According to some embodiments of the present invention, the thickness of the nitrided layer is 5-15 μm.

[0010] According to some embodiments of the present invention, the microVickers hardness HV of the nitrided layer 0.05 The range is 550-900, of which HV 0.05 It refers to the Vickers hardness value measured under a load of 0.05 kgf.

[0011] According to some embodiments of the present invention, the microVickers hardness HV of the nitrided layer 0.05 It is 600-800.

[0012] According to some embodiments of the present invention, the ratio of the thickness of the nitrided layer to the diameter of the crankshaft is (0.00027-0.0009):1.

[0013] According to some embodiments of the present invention, the ratio of the thickness of the nitrided layer to the diameter of the crankshaft is (0.0003-0.0008):1.

[0014] Specifically, the nitriding layer, as a hard layer, can significantly improve the fatigue strength and wear resistance of the crankshaft. If the nitriding layer is too thin and has low load-bearing capacity, its improvement on the fatigue strength and wear resistance of the crankshaft is limited, and it cannot play its wear-resistant role well, increasing the probability of wear of the crankshaft-bearing friction pair. If the nitriding layer is too thick, it takes longer to reach a certain thickness or the nitrogen potential is higher, which may cause obvious loose structure on the surface of the nitriding layer, generating ε-Fe2N brittle phase, increasing the brittleness of the nitriding layer, and leading to deterioration of wear resistance. This invention, by reasonably limiting the thickness of the nitriding layer, can ensure the fatigue strength and wear resistance of the crankshaft, thereby ensuring the reliability of the crankshaft-bearing friction pair and reducing the wear of the crankshaft-bearing friction pair.

[0015] According to some embodiments of the present invention, the composition of the nitrided layer includes iron nitride.

[0016] According to some embodiments of the present invention, the iron nitride comprises ε-Fe 2-3 Fe4N in N and γ' phases.

[0017] According to some embodiments of the present invention, the components of the phosphate layer include manganese phosphate.

[0018] According to some embodiments of the present invention, the thickness of the phosphate layer is 1.2-3.0 μm.

[0019] According to some embodiments of the present invention, the roughness Rz of the phosphate layer is greater than 1.8.

[0020] According to some embodiments of the present invention, the roughness Rz of the phosphate layer is greater than 2.0.

[0021] According to some embodiments of the present invention, the roughness Rz of the phosphate layer is greater than 2.0 and less than or equal to 4.0.

[0022] Specifically, the bonding force between the lubricating layer and the substrate is positively correlated with the contact area between them. A phosphate layer with a certain degree of roughness increases the contact area between the lubricating layer and the substrate, thus improving the bonding strength. However, the roughness of the phosphate layer should not be too large. If the roughness is too large, the corresponding manganese phosphate particles will be too large, resulting in a smaller contact area between the lubricating layer and the substrate, a decrease in bonding strength, and a deterioration in the wear resistance of the lubricating layer, reducing its lifespan. Conversely, the roughness of the phosphate layer should not be too small either, as this will also reduce the contact area between the lubricating layer and the substrate, decrease the interlayer meshing force, and reduce the bonding strength between the phosphate layer and the lubricating layer. This prevents the lubricating layer from adhering well to the phosphate layer, reducing its stability and durability, increasing the risk of lubrication failure due to interlayer peeling or detachment, and consequently increasing friction and wear, exacerbating the wear of the crankshaft-bearing friction pair, and increasing the risk of bearing wear. This invention, by reasonably limiting the roughness of the phosphate layer, allows the lubricating layer to fully exert its function of reducing friction and wear, thereby better ensuring the wear resistance and service life of the crankshaft, reducing the wear of the crankshaft-bearing friction pair, and reducing the risk of bearing wear.

[0023] According to some embodiments of the present invention, the components of the lubricating layer include resin and friction reducer.

[0024] Specifically, the lubricating layer is a composite coating formed by organic resin and friction reducer. The polymer material is easy to plastically deform and is compatible with the mating surfaces, so it can increase the actual contact area between the friction pairs, reduce the interfacial contact stress, and reduce the risk of the nitrided layer cracking and failing due to excessive load.

[0025] According to some embodiments of the present invention, the mass ratio of the friction reducer to the resin is (0.45-2.2):1.

[0026] According to some embodiments of the present invention, the mass ratio of the friction reducer to the resin is (0.5-2):1.

[0027] Specifically, if the mass ratio of the friction reducer to resin is too low, i.e., the friction reducer content is low, it is difficult to form a stable solid lubricating layer. The lubricating layer has poor friction-reducing performance, a high wear rate, and is prone to wear. Conversely, if the mass ratio of the friction reducer to resin is too high, i.e., the friction reducer content is high, although the friction-reducing performance is good, the excessive presence of friction reducer will lead to a decrease in the overall strength and hardness of the lubricating layer, poor density, and deteriorated wear resistance, thus exacerbating the wear of the crankshaft-bearing friction pair. This invention, by appropriately limiting the ratio of friction reducer to resin, enables the lubricating layer to possess both excellent friction-reducing and wear-resistant properties, reducing the wear of the crankshaft-bearing friction pair and ensuring its reliability.

[0028] According to some embodiments of the present invention, the resin includes at least one selected from polyimide, polyamide-imide, polyphenylene sulfide, polyetheretherketone, and epoxy resin.

[0029] According to some embodiments of the present invention, the friction reducing agent includes at least one of metal disulfide, graphite and polytetrafluoroethylene (PTFE).

[0030] According to some embodiments of the present invention, the metal disulfide includes at least one of molybdenum disulfide and tungsten disulfide.

[0031] Specifically, the resin in the lubricating layer of this invention acts as a binder. By selecting appropriate resin types and combining them with appropriate friction-reducing agents, the lubricating layer achieves good adhesion to the phosphate layer, reducing the probability of interlayer peeling or detachment. Furthermore, it ensures the friction-reducing agent remains stably within the resin to exert its friction-reducing effect, guaranteeing the friction-reducing and wear-resistant properties of the lubricating layer. In addition, the resin-based lubricating coating is easily plastically deformable, adapting to the mating surfaces, increasing the actual contact area between the friction pairs, alleviating stress concentration, reducing the risk of the nitrided layer cracking due to excessive load, improving the wear resistance of the crankshaft-bearing friction pair, and reducing the wear of the crankshaft-bearing friction pair.

[0032] According to some embodiments of the present invention, the thickness of the lubricating layer is 5-15 μm.

[0033] According to some embodiments of the present invention, the thickness of the lubricating layer is 8-12 μm.

[0034] Specifically, the lubricating layer reduces friction and wear. A suitable lubricating layer thickness ensures the organic lubricating layer achieves optimal lubrication, enhances crankshaft lubrication performance, reduces friction and heat generation during operation, and thus improves the overall efficiency of the compressor. If the lubricating layer thickness is too low, its lubricity will decrease, consequently reducing its friction-reducing and wear-resistant effects. If the lubricating layer thickness is too high, the bonding strength between the lubricating layer and the phosphate layer may decrease, leading to easy delamination and preventing the lubricating, friction-reducing, and wear-resistant functions from being performed, thus reducing the crankshaft's wear resistance and exacerbating the wear of the crankshaft-bearing friction pair. This invention, by limiting the thickness of the lubricating layer, ensures its friction-reducing and wear-resistant properties, giving the crankshaft good wear resistance while reducing the wear of the crankshaft-bearing friction pair and ensuring its reliability.

[0035] According to some embodiments of the present invention, the base material of the crankshaft includes any one of cast ductile iron, forged structural carbon steel, and forged alloy steel.

[0036] According to some embodiments of the present invention, the matrix structure of the crankshaft includes any one of ferrite / pearlite mixed structure, pearlite structure, and tempered martensite structure.

[0037] Specifically, the ferrite / pearlite mixed structure, pearlite structure, or tempered martensite structure accounts for more than 80% of the volume of the matrix structure.

[0038] A second aspect of the present invention provides a method for preparing the crankshaft described in the first aspect of the present invention.

[0039] Specifically, the method for manufacturing the crankshaft includes the following steps:

[0040] The surface of the crankshaft body is subjected to nitriding and phosphating treatments in sequence to form the nitriding layer and the phosphate layer. The components of the lubricating layer are prepared into a slurry and then sprayed onto the crankshaft that has undergone nitriding and phosphating treatments. After curing, the lubricating layer is formed, and the crankshaft is obtained.

[0041] According to some embodiments of the present invention, the nitriding treatment method includes any one of gas soft nitriding and salt bath soft nitriding.

[0042] According to some embodiments of the present invention, the nitriding treatment temperature is 560-580°C, and the nitriding treatment time is 0.5-6 hours.

[0043] According to some embodiments of the present invention, the nitriding treatment temperature is 560-570°C, and the nitriding treatment time is 0.5-3 hours.

[0044] According to some embodiments of the present invention, the phosphating treatment is performed using a phosphating solution, wherein the phosphating solution comprises manganese phosphate.

[0045] According to some embodiments of the present invention, the temperature of the phosphating treatment is 85-95°C, and the time of the phosphating treatment is 5-30 min.

[0046] According to some embodiments of the present invention, the temperature of the phosphating treatment is 90-95°C, and the time of the phosphating treatment is 10-30 min.

[0047] Specifically, through specific nitriding and phosphating treatments, a high-hardness nitride layer is first obtained on the surface of the crankshaft body as a nitriding layer, which can significantly improve the fatigue strength and wear resistance of the crankshaft. Then, a phosphate layer is obtained on the nitriding layer. Finally, a lubricating layer is formed on the phosphate layer by spraying. The phosphate layer, as the underlayer, helps to enhance the adhesion of the solid lubricating coating and improve the bonding between the phosphate layer and the lubricating layer. This allows the lubricating layer to better play its role in reducing friction and wear, ensuring the wear resistance of the crankshaft while significantly improving the wear of the crankshaft-bearing friction pair and significantly reducing the risk of bearing wear.

[0048] According to some embodiments of the present invention, the slurry is prepared by mixing the components of the lubricating layer and a solvent.

[0049] According to some embodiments of the present invention, the process prior to curing also includes a surface drying process.

[0050] A third aspect of the present invention provides a compressor.

[0051] Specifically, the compressor includes the crankshaft described in the first aspect of the present invention.

[0052] Specifically, the crankshaft provided by this invention possesses excellent lubrication, friction reduction, and wear resistance properties, ensuring lubrication between the crankshaft and bearing friction pairs, significantly improving wear on these pairs, and markedly reducing the risk of bearing wear. When applied to compressors, it enhances compressor reliability, enabling stable operation under higher loads and for longer periods. Furthermore, due to the effective protection and lubrication of the crankshaft surface, the wear risk of the crankshaft-bearing friction pairs is greatly reduced, lowering compressor maintenance frequency, thereby reducing maintenance costs and downtime, improving production efficiency, and resulting in significant economic benefits.

[0053] A fourth aspect of the present invention provides a temperature regulating device.

[0054] Specifically, the temperature regulating device includes the crankshaft described in the first aspect of the present invention, or the compressor described in the third aspect of the present invention.

[0055] According to some embodiments of the present invention, the temperature regulating device includes any one of an air conditioner and a refrigerator.

[0056] Specifically, the crankshaft provided by this invention has good lubrication, friction reduction and wear resistance properties, which can ensure lubrication between the crankshaft and bearing friction pairs, significantly improve the wear of the crankshaft and bearing friction pairs, and make the compressor have good reliability and stability, thereby ensuring the reliability of temperature regulation equipment such as air conditioners and refrigerators during use and extending the service life of the equipment. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the crankshaft structure in Embodiment 1 of the present invention.

[0058] Among them, 11 is the crankshaft body, 12 is the nitrided layer, 13 is the phosphate layer, and 14 is the lubricating layer. Detailed Implementation

[0059] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0060] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0061] A first aspect of the present invention provides a crankshaft, including a crankshaft body and a composite layer disposed on the surface of the crankshaft body; the composite layer includes a nitriding layer, a phosphate layer and a lubricating layer disposed sequentially from the inside to the outside.

[0062] In the above "from the inside out" description, "inside" refers to the layer closest to the crankshaft body, and "outside" refers to the layer furthest from the crankshaft body. Specifically, the nitrided layer is close to the crankshaft body, while the lubricating layer is furthest from the crankshaft body.

[0063] In this embodiment of the invention, a high-hardness nitride layer is first formed on the crankshaft surface as a nitride layer, which can significantly improve the fatigue strength and wear resistance of the crankshaft. Then, a phosphate layer and a lubricating layer are sequentially formed on the nitride layer. The phosphate layer formed on the nitride layer can serve as a base layer, providing a good adhesion foundation for the lubricating layer, which is beneficial to enhancing the adhesion of the lubricating layer and improving the bonding between the phosphate layer and the lubricating layer, that is, improving the bonding between the lubricating layer and the crankshaft body. This reduces lubrication failure or protective failure caused by interlayer peeling or detachment, allowing the lubricating layer to better perform its function of reducing friction and wear. When the crankshaft-bearing friction pair enters the boundary lubrication state, the solid lubricating layer is consumed first, forming a solid lubricating transfer film on the bearing surface. This avoids direct contact between the crankshaft nitride layer and the bearing, and also achieves the effect of friction reduction and lubrication.

[0064] In other words, by sequentially setting a nitrided layer, a phosphate layer and a lubricating layer on the surface of the crankshaft body, the present invention can improve the wear resistance of the crankshaft itself, while ensuring the lubrication between the crankshaft and bearing friction pairs, significantly improving the wear of the crankshaft and bearing friction pairs, and significantly reducing the risk of bearing wear.

[0065] According to some embodiments of the present invention, the thickness of the nitride layer is 4.5-18 μm, and the microVickers hardness of the nitride layer is HV. 0.05 It is 550-880.

[0066] According to some embodiments of the present invention, the thickness of the nitrided layer is 5-15 μm, and the microVickers hardness of the nitrided layer is HV. 0.05 The value is 600-800; for example, the thickness of the nitrided layer is 4.5μm, 5μm, 8μm, 10μm, 12μm or 15μm; the microVickers hardness of the nitrided layer is HV. 0.05 It is 680-700HV.

[0067] According to some embodiments of the present invention, the ratio of the thickness of the nitrided layer to the crankshaft diameter is (0.00027-0.0009):1.

[0068] According to some embodiments of the present invention, the ratio of the thickness of the nitrided layer to the crankshaft diameter is (0.0003-0.0008):1.

[0069] The crankshaft diameter mentioned above refers to the diameter of the crankshaft.

[0070] In this invention, the nitrided layer, as a hard layer, can significantly improve the fatigue strength and wear resistance of the crankshaft. If the nitrided layer is too thin, its improvement on the fatigue strength and wear resistance of the crankshaft is limited, and it cannot play its wear-resistant role well, increasing the probability of wear of the crankshaft-bearing friction pair. If the nitrided layer is too thick, loose and brittle phases are prone to appear, which deteriorates the wear resistance. This invention, by reasonably limiting the thickness of the nitrided layer, can ensure the fatigue strength and wear resistance of the crankshaft. While improving the wear resistance of the crankshaft itself, it can also improve the wear of the crankshaft-bearing friction pair and significantly reduce the risk of bearing wear.

[0071] According to some embodiments of the present invention, the composition of the nitrided layer includes iron nitride.

[0072] According to some embodiments of the present invention, iron nitride comprises ε-Fe 2-3 Fe4N in N and γ' phases.

[0073] According to some embodiments of the present invention, the components of the phosphate layer include manganese phosphate.

[0074] According to some embodiments of the present invention, the thickness of the phosphate layer is 1.2-3.0 μm.

[0075] According to some embodiments of the present invention, the roughness Rz of the phosphate layer is greater than 1.8.

[0076] According to some embodiments of the present invention, the roughness Rz of the phosphate layer is greater than 2.0.

[0077] According to some embodiments of the present invention, the roughness Rz of the phosphate layer is greater than 2.0 and less than or equal to 4.0.

[0078] According to some embodiments of the present invention, the roughness Rz of the phosphate layer is 2.2-2.8.

[0079] This invention, by reasonably limiting the roughness of the phosphate layer, can better ensure the bonding force between the lubricating layer and the phosphate layer, allowing the lubricating layer to fully exert its function of reducing friction and wear, thus better ensuring the wear resistance and service life of the crankshaft, and ultimately improving the wear of the crankshaft-bearing friction pair. The bonding force between the lubricating layer and the substrate is positively correlated with the contact area between them. A phosphate layer with a certain roughness increases the contact area between the lubricating layer and the substrate, thereby improving the bonding strength between the lubricating layer and the substrate. However, the roughness of the phosphate layer should not be too large. If the roughness is too large, the corresponding manganese phosphate particles will be too large, resulting in a smaller contact area between the lubricating layer and the substrate, a decrease in bonding strength, and a deterioration in the wear resistance of the lubricating layer, thus reducing its lifespan. Conversely, the roughness of the phosphate layer should not be too small either, as this will also reduce the contact area between the lubricating layer and the substrate, decrease the interlayer meshing force, and reduce the bonding strength between the phosphate layer and the lubricating layer. This will prevent the lubricating layer from adhering well to the phosphate layer, reducing the stability and durability of the lubricating layer, increasing the risk of lubrication failure due to interlayer peeling or detachment, and consequently increasing friction and wear, exacerbating the wear of the crankshaft-bearing friction pair, and increasing the risk of bearing wear.

[0080] According to some embodiments of the present invention, the components of the lubricating layer include resin and friction reducer.

[0081] The lubricating layer in this embodiment of the invention is a composite coating formed by bonding an organic resin with a friction reducer. The polymer material is easy to plastically deform and is compatible with the mating surfaces, so it can increase the actual contact area between the friction pairs, reduce the interfacial contact stress, and reduce the risk of the nitrided layer cracking and failing due to excessive load.

[0082] According to some embodiments of the present invention, the mass ratio of friction reducer to resin is (0.45-2.2):1.

[0083] According to some embodiments of the present invention, the mass ratio of friction reducer to resin is (0.45-2.0):1.

[0084] According to some embodiments of the present invention, the mass ratio of friction reducer to resin is (0.5-1.8):1.

[0085] According to some embodiments of the present invention, the mass ratio of friction reducer to resin is 1:1.

[0086] This invention, by limiting the appropriate ratio of friction reducer to resin, enables the lubricating layer to possess both excellent friction reduction and wear resistance properties. This improves the wear resistance of the crankshaft while reducing wear on the crankshaft-bearing friction pair. If the mass ratio of friction reducer to resin is too low (i.e., the friction reducer content is low), it is difficult to form a stable solid lubricating layer, resulting in poor friction reduction performance, a higher wear rate, decreased crankshaft wear resistance, and accelerated wear on the crankshaft-bearing friction pair. Conversely, if the mass ratio of friction reducer to resin is too high, although the friction reduction performance is good, the excessive presence of friction reducer leads to a decrease in the overall strength and hardness of the lubricating layer, poor density, and deteriorated wear resistance, similarly reducing crankshaft wear resistance and increasing the probability of wear on the crankshaft-bearing friction pair.

[0087] According to some embodiments of the present invention, the resin includes at least one of polyimide, polyamide-imide, polyphenylene sulfide, polyetheretherketone, and epoxy resin.

[0088] According to some embodiments of the present invention, the friction reducer includes at least one of metal disulfide, graphite and polytetrafluoroethylene (PTFE).

[0089] According to some embodiments of the present invention, the metal disulfide includes at least one of molybdenum disulfide and tungsten disulfide.

[0090] In this embodiment of the invention, the resin in the lubricating layer is used as an adhesive. By selecting a reasonable type of resin and a reasonable type of friction reducer, the lubricating layer has a good adhesion effect on the phosphate layer, giving full play to its lubrication and friction reduction functions. The friction reducer is stably present in the resin to exert its friction reduction effect, so that the lubricating layer has good friction reduction and wear resistance. While improving the wear resistance of the crankshaft, it reduces the wear of the crankshaft-bearing friction pair.

[0091] According to some embodiments of the present invention, the thickness of the lubricating layer is 5-15 μm.

[0092] According to some embodiments of the present invention, the thickness of the lubricating layer is 8-12 μm.

[0093] According to some embodiments of the present invention, the thickness of the lubricating layer is 10 μm.

[0094] This invention, by limiting the thickness of the lubricating layer, ensures its friction-reducing and wear-resistant properties, thereby giving the crankshaft good wear resistance and reducing wear on the crankshaft-bearing friction pair. The lubricating layer reduces friction and wear; a reasonable thickness ensures the organic lubricating layer achieves optimal lubrication, enhances crankshaft lubrication performance, reduces friction and heat generation during operation, and thus improves the overall efficiency of the compressor. If the lubricating layer thickness is too low, its lubricity will decrease, thereby reducing its friction-reducing and wear-resistant effects. If the lubricating layer thickness is too high, the bonding strength between the lubricating layer and the phosphate layer may decrease, leading to easy delamination between the layers, failing to effectively perform its lubrication, friction-reducing, and wear-resistant functions, reducing the crankshaft's wear resistance and service life, and increasing wear on the crankshaft-bearing friction pair.

[0095] According to some embodiments of the present invention, the base material of the crankshaft includes any one of cast ductile iron, forged structural carbon steel, and forged alloy steel.

[0096] According to some embodiments of the present invention, the matrix structure of the crankshaft includes any one of ferrite / pearlite mixed structure, pearlite structure, and tempered martensite structure.

[0097] In the matrix structure of the crankshaft of the present invention, ferrite / pearlite mixed structure, pearlite structure or tempered martensite structure accounts for more than 80% of the matrix structure.

[0098] A second aspect of this invention provides a method for manufacturing a crankshaft according to the first aspect of this invention, comprising the following steps:

[0099] The surface of the crankshaft body is subjected to nitriding and phosphating treatments in sequence to form a nitriding layer and a phosphate layer. The components of the lubricating layer are prepared into a slurry and then sprayed onto the nitrided and phosphated crankshaft. After curing, the lubricating layer is formed, and the crankshaft is obtained.

[0100] According to some embodiments of the present invention, the nitriding treatment method includes any one of gas soft nitriding and salt bath soft nitriding.

[0101] According to some embodiments of the present invention, the nitriding temperature is 560-580°C and the nitriding time is 0.5-6 hours.

[0102] According to some embodiments of the present invention, the nitriding temperature is 560-570°C and the nitriding time is 0.5-3 hours.

[0103] According to some embodiments of the present invention, the nitriding temperature is 560°C and the nitriding time is 2 hours.

[0104] According to some embodiments of the present invention, the phosphating treatment is carried out by using a phosphating solution, which includes manganese phosphate.

[0105] According to some embodiments of the present invention, the phosphating temperature is 85-95°C and the phosphating time is 5-30 min.

[0106] According to some embodiments of the present invention, the phosphating temperature is 90-95°C and the phosphating time is 10-30 min.

[0107] According to some embodiments of the present invention, the phosphating temperature is 95°C and the phosphating time is 10 min.

[0108] This invention employs specific nitriding and phosphating treatments to first obtain a high-hardness nitride layer on the surface of the crankshaft body as a nitriding layer, which can significantly improve the fatigue strength and wear resistance of the crankshaft. Then, a phosphate layer is obtained on the nitriding layer. Finally, a lubricating layer is formed on the phosphate layer by spraying. The phosphate layer, as a base layer, helps to enhance the adhesion of the solid lubricating coating and improve the bonding between the phosphate layer and the lubricating layer. This allows the lubricating layer to better play its role in reducing friction and wear, ensuring the wear resistance of the crankshaft while significantly improving the wear of the crankshaft-bearing friction pair and significantly reducing the risk of bearing wear.

[0109] According to some embodiments of the present invention, the slurry is prepared by mixing the components of the lubricating layer and a solvent.

[0110] According to some embodiments of the present invention, a surface drying process is also included before curing.

[0111] A third aspect of the present invention provides a compressor.

[0112] The compressor of this invention includes the crankshaft of the first aspect of this invention.

[0113] The crankshaft provided in this invention has excellent lubrication, friction reduction, and wear resistance properties, which can improve the wear of the crankshaft-bearing friction pair, reduce the risk of bearing wear, and thus improve the reliability of the compressor, enabling it to remain stable under higher loads and longer operating times. Furthermore, due to the effective protection and lubrication of the crankshaft surface, the compressor maintenance frequency can be reduced, thereby lowering maintenance costs and downtime, improving production efficiency, and resulting in good economic benefits.

[0114] A fourth aspect of the present invention provides a temperature regulating device.

[0115] The temperature regulating device of this invention includes a crankshaft according to the first aspect of this invention, or a compressor according to the third aspect of this invention.

[0116] According to some embodiments of the present invention, the temperature regulating device includes any one of an air conditioner and a refrigerator.

[0117] The crankshaft provided in this embodiment of the invention has good lubrication, friction reduction and wear resistance properties, which can ensure lubrication between the crankshaft and bearing friction pair. The good wear resistance of the crankshaft and bearing friction pair makes the compressor have good reliability and stability, thereby ensuring the reliability of temperature regulation equipment such as air conditioners and refrigerators during use and extending the service life of the equipment.

[0118] The present invention will be further described in detail below through specific embodiments and comparative examples.

[0119] The salt bath nitriding treatment in the embodiments and comparative examples of the present invention is a conventional process in the art, and the AB salt bath oxidation treatment in Comparative Example 3 is a conventional process in the art.

[0120] Example 1

[0121] A crankshaft includes a crankshaft body and a composite layer disposed on the surface of the crankshaft body; the composite layer consists of a nitriding layer, a phosphate layer and a lubricating layer disposed sequentially from the inside to the outside;

[0122] The thickness of the nitrided layer is 4 μm, and the microVickers hardness of the nitrided layer is HV. 0.05 480-520 HV;

[0123] The nitrided layer is composed of iron nitride, consisting of ε-phase Fe. 2-3 The Fe4N composition consists of N and γ' phases;

[0124] The phosphate layer is composed of manganese iron phosphate particles ((Mn,Fe)5H2(PO4)4·4H2O), with a roughness Rz of 1.1-1.5;

[0125] The lubricating layer consists of resin and friction reducer, with a mass ratio of resin to friction reducer of 1:1.

[0126] The resin is polyamide-imide; the friction reducer is molybdenum disulfide, graphite and PTFE, and the mass ratio of molybdenum disulfide, graphite and PTFE is 4:2:1;

[0127] The thickness of the lubricating layer is 10μm; the base material of the crankshaft is 45# steel.

[0128] A method for manufacturing a crankshaft includes the following steps:

[0129] (1) The crankshaft body after fine machining is degreased and pickled to remove surface oil and oxide layer, and then subjected to salt bath nitriding treatment. The salt bath nitriding treatment temperature is 560℃ and the salt bath nitriding treatment time is 2h, and a nitriding layer is obtained on the outer surface of the crankshaft body. Then it is placed in a phosphating tank for manganese phosphating treatment. The phosphating treatment temperature is 95℃ and the phosphating treatment time is 10min, and a fine manganese phosphate salt layer with an average thickness of 2.2μm is obtained on the surface of the nitriding layer.

[0130] (2) Mix the resin, friction reducer, solvent N-methylpyrrolidone and dimethylacetamide evenly to obtain a slurry. Spray the prepared slurry onto the surface of the phosphate layer obtained in step (1). First, dry the surface at 80°C for 15 minutes to promote the evaporation of most of the solvent. Then transfer it to an oven and cure it at 230°C for 1 hour to obtain a lubricating layer. Thus, the crankshaft body has a nitriding layer, a phosphate layer and a lubricating layer on its surface from the inside out.

[0131] A schematic diagram of the crankshaft structure in Embodiment 1 of the present invention is shown below. Figure 1 As shown.

[0132] Example 2

[0133] The only difference between Example 2 and Example 1 is that the thickness of the nitrided layer in Example 2 is 10 μm, and the microVickers hardness of the nitrided layer is HV. 0.05 The voltage is 680-700 HV, and other parameters are the same as in Example 1.

[0134] Example 3

[0135] The only difference between Example 3 and Example 1 is that the thickness of the nitrided layer in Example 3 is 10 μm, and the microVickers hardness of the nitrided layer is HV. 0.05 The value is 680-700 HV, and the roughness Rz of the phosphate layer is 2.2-2.8. Other parameters are the same as in Example 1.

[0136] Comparative Example 1

[0137] The only difference between Comparative Example 1 and Example 1 is that Comparative Example 1 only undergoes salt bath nitriding treatment, that is, the crankshaft body surface only has a nitriding layer, and the parameters and preparation process of the nitriding layer are the same as those of Example 1.

[0138] Comparative Example 2

[0139] The only difference between Comparative Example 2 and Example 1 is that Comparative Example 2 was not phosphated. That is, the composite layer on the surface of the crankshaft body of Comparative Example 2 consists of a nitrided layer and a lubricating layer from the inside out, and does not contain a phosphate layer. Otherwise, it is the same as Example 1.

[0140] Comparative Example 3

[0141] The only difference between Comparative Example 3 and Example 1 is that the composite layer on the surface of the crankshaft body in Comparative Example 3 consists of a nitrided layer and an oxide layer from the inside out, without a lubricating layer. The thickness of the oxide layer is the same as that of the phosphate layer in Example 1, and the composition of the oxide layer is Fe3O4. Everything else is the same as in Example 1.

[0142] The preparation method of the crankshaft in Comparative Example 3 includes the following steps:

[0143] Using the same method as in Example 1, a nitrided layer was first obtained on the surface of the crankshaft body, followed by AB salt bath oxidation treatment at 430°C for 1 hour to obtain an oxide layer on the nitrided layer, thus obtaining the crankshaft.

[0144] Comparative Example 4

[0145] The only difference between Comparative Example 4 and Example 1 is that Comparative Example 4 does not have a lubrication layer. That is, the composite layer on the surface of the crankshaft body of Comparative Example 4 consists of a nitrided layer and a phosphate layer from the inside out. Otherwise, it is the same as Example 1.

[0146] Comparative Example 5

[0147] The only difference between Comparative Example 5 and Example 1 is that Comparative Example 5 does not have a nitriding layer. That is, the composite layer on the surface of the crankshaft body of Comparative Example 5 consists of a phosphate layer and a lubricating layer from the inside out. Otherwise, it is the same as Example 1.

[0148] Performance testing

[0149] The wear resistance and coefficient of friction of the crankshafts of Examples 1-3 and Comparative Examples 1-5 were determined. The specific test methods are as follows:

[0150] Wear resistance and coefficient of friction: Test blocks with the same base material and composite layer structure as the crankshaft body in the examples / comparative examples were used. The wear resistance of the friction pair was evaluated by a standard ball-disc friction and wear test. Disc-shaped specimens made of 45# steel with composite layers from Examples 1-3 and Comparative Examples 1-5 were prepared as the lower friction pair, while the upper friction pair used SUS304 stainless steel balls. The load was set to 5N. The wear resistance of the crankshaft friction pairs with different composite layer structures in Examples 1-3 and Comparative Examples 1-5 was evaluated by measuring the wear amount of the upper and lower friction pairs after running at a certain speed for the same amount of time. The wear volume was calculated by measuring the wear track profile integral using a laser scanning confocal microscope. Furthermore, the coefficient of friction was measured using a multi-functional friction tester. During a single friction test, the coefficient of friction changes over time. Typically, after the initial break-in period, the coefficient of friction decreases compared to the initial value, forming a relatively stable plateau. This plateau was used as the range for the coefficient of friction.

[0151] The wear resistance and friction coefficient results of the crankshafts in Examples 1-3 and Comparative Examples 1-5 are shown in Table 1.

[0152] Table 1: Test results of wear resistance and coefficient of friction of crankshafts in Examples 1-3 and Comparative Examples 1-5 (wear amount unit: 10) - 4 mm 3 )

[0153] Group Wear (disk) Wear (ball) coefficient of friction Example 1 18.4 0.9 0.042～0.058 Example 2 14.2 0.3 0.040～0.056 Example 3 10.7 0.3 0.040～0.056 Comparative Example 1 45.9 848.7 0.154～0.278 Comparative Example 2 18.6 9.1 0.048～0.123 Comparative Example 3 35.5 437.6 0.151～0.263 Comparative Example 4 42.6 184.3 0.118～0.236 Comparative Example 5 27.3 2.1 0.041～0.058

[0154] As shown in Table 1, in the standard ball-disc friction and wear test, the wear of the standard disk with the same composite layer structure as the present invention is lower, and the wear of the ball is also lower. This indicates that the composite layer on the surface of the crankshaft body of the present invention has good wear resistance and can improve the wear between the disk and the ball. This also shows that the crankshaft prepared by the present invention has good wear resistance. While ensuring the wear resistance of the crankshaft itself, it can also ensure the reliability of the crankshaft-bearing friction pair and reduce the wear of the crankshaft-bearing friction pair.

[0155] Compared with Example 1, Comparative Example 1 only contains a nitrided layer, which significantly increases the wear of both the disc and the ball in the standard ball-disc friction and wear test of the crankshaft of Comparative Example 1, resulting in poor wear resistance of the crankshaft-bearing friction pair.

[0156] Compared with Example 1, Comparative Example 2 does not contain a phosphate layer, but only a nitriding layer and a lubricating layer. As a result, in the standard ball-disc friction and wear test, the wear of the ball in Comparative Example 2 crankshaft is significantly increased, the wear resistance of the crankshaft-bearing friction pair is worse, and the wear of the bearing is aggravated.

[0157] Compared with Example 1, the composite layer on the surface of the crankshaft body of Comparative Example 3 consists of a nitrided layer and an oxide layer from the inside out, without a lubricating layer. As a result, the wear of the ball is significantly increased in the standard ball-disc friction and wear test of the crankshaft of Comparative Example 3, which aggravates the wear of the bearing.

[0158] Compared to Example 1, Comparative Example 4 does not contain a lubricating layer, which significantly increases the wear of the balls in the standard ball-disc friction and wear test of the crankshaft in Comparative Example 4, thus aggravating the wear of the bearing.

[0159] Compared with Example 1, Comparative Example 5, which does not contain a nitrided layer, significantly increased the wear of the disc, reduced the wear resistance of the crankshaft, and worsened the wear resistance of the crankshaft-bearing friction pair.

[0160] It is known that the nitrided layer, phosphate layer and lubricating layer in the composite layer on the surface of the crankshaft body are all indispensable. The absence of any one of these layers will significantly increase the wear of the crankshaft-bearing friction pair and reduce the wear resistance of the crankshaft friction pair-bearing.

[0161] In summary, this invention first sets a high-hardness nitride hard layer on the crankshaft surface as a nitride layer, which can significantly improve the fatigue strength and wear resistance of the crankshaft. Then, a phosphate layer and a lubricating layer are sequentially set on the nitride layer of the crankshaft. The phosphate layer formed on the nitride layer can serve as a base layer, providing a good adhesion foundation for the lubricating layer, which is beneficial to enhancing the adhesion of the lubricating layer and improving the bonding between the phosphate layer and the lubricating layer, that is, improving the bonding between the lubricating layer and the crankshaft body. This reduces lubrication failure or protection failure caused by interlayer peeling or detachment, allowing the lubricating layer to better play its role in reducing friction and wear. When the crankshaft-bearing friction pair enters the boundary lubrication state, the solid lubricating layer is consumed first, forming a solid lubricating transfer film on the bearing surface. This avoids direct contact between the crankshaft nitride layer and the bearing, and also plays a role in reducing friction and lubrication. This ensures lubrication between the crankshaft-bearing friction pair, significantly improves the wear of the crankshaft-bearing friction pair, and significantly reduces the risk of bearing wear.

[0162] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A crankshaft, characterized in that, It includes a crankshaft body and a composite layer disposed on the surface of the crankshaft body; the composite layer includes a nitriding layer, a phosphate layer and a lubricating layer disposed sequentially from the inside to the outside.

2. The crankshaft according to claim 1, characterized in that, The thickness of the nitrided layer is 4.5-18 μm; and / or, the micro Vickers hardness HV of the nitrided layer is... 0.05 It is 550-900.

3. The crankshaft according to claim 1, characterized in that, The ratio of the thickness of the nitrided layer to the diameter of the crankshaft is (0.00027-0.0009):

1.

4. The crankshaft according to claim 1, characterized in that, The nitrided layer comprises iron nitride.

5. The crankshaft according to claim 1, characterized in that, The phosphate layer comprises manganese phosphate; and / or the roughness Rz of the phosphate layer is greater than 1.

8.

6. The crankshaft according to claim 1, characterized in that, The components of the lubricating layer include resin and friction reducer.

7. The crankshaft according to claim 6, characterized in that, The mass ratio of the friction reducer to the resin is (0.45-2.2):

1.

8. The crankshaft according to claim 6, characterized in that, The resin includes at least one of polyimide, polyamide-imide, polyphenylene sulfide, polyetheretherketone, and epoxy resin; and / or the friction reducer includes at least one of metal disulfide, graphite, and polytetrafluoroethylene.

9. The crankshaft according to claim 1, characterized in that, The thickness of the lubricating layer is 5-15 μm.

10. The crankshaft according to any one of claims 1-9, characterized in that, The matrix structure of the crankshaft includes any one of the following: ferrite / pearlite mixed structure, pearlite structure, and tempered martensite structure.

11. The method for preparing a crankshaft according to any one of claims 1-10, characterized in that, Includes the following steps: The crankshaft body is subjected to nitriding and phosphating treatments in sequence to form the nitriding layer and the phosphate layer. The components of the lubricating layer are prepared into a slurry and then sprayed onto the crankshaft that has undergone nitriding and phosphating treatments. After curing, the lubricating layer is formed, thus obtaining the crankshaft.

12. The preparation method according to claim 11, characterized in that, The nitriding treatment method includes any one of gas soft nitriding and salt bath soft nitriding; and / or, the nitriding treatment temperature is 560-580℃, and the nitriding treatment time is 0.5-6h; and / or, the phosphating treatment method is to use a phosphating solution, the phosphating solution including manganese phosphate; and / or, the phosphating treatment temperature is 85-95℃, and the phosphating treatment time is 5-30min.

13. A compressor, characterized in that, Includes the crankshaft as described in any one of claims 1-10.

14. A temperature regulating device, characterized in that, Includes the crankshaft as described in any one of claims 1-10, or the compressor as described in claim 13.

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