Layered composite coating damping wear-resistant bearing for automobile

Abstract

The invention relates to the technical field of automobile bearings, and discloses a layered composite coating damping wear-resistant bearing for an automobile. The bearing comprises an inner ring, an outer ring, rolling balls, an elastic bushing and a retainer, wherein layered composite coatings are arranged on the outer surface of the inner ring and the inner surface of the outer ring; the layered composite coating sequentially comprises a nickel-phosphorus alloy bottom layer (the thickness is 5-8 microns, and the chemical plating process is adopted), a polyurethane-nano silicon dioxide composite middle layer (the thickness is 10-15 microns, and the mass ratio of nano silicon dioxide is 15%-20%) and a diamond-like carbon (DLC) surface layer (the thickness is 2-3 microns, and the magnetron sputtering process is adopted) from the base material to the outside. And the elastic bushing is made of hydrogenated nitrile rubber (ShoreA hardness is 65-70) and is embedded in a gap between the outer ring and the mounting seat. Through the synergistic effect of the layered composite coating and the elastic lining, the problem that wear resistance and shock absorption of a traditional automobile bearing coating are difficult to consider at the same time is solved, the bearing operation noise is reduced by 8-12 dB, the service life is prolonged by 40% or above, and the automobile bearing coating is suitable for an automobile transmission system.

Description

Technical Field

[0001] This invention relates to the field of automotive bearing technology, and specifically to a layered composite coating shock-absorbing and wear-resistant bearing for automobiles. Background Technology

[0002] As the core hub for power transmission in a vehicle, the stability of the automotive transmission system directly determines the vehicle's handling, comfort, and reliability. Bearings, as key load-bearing components in the transmission system, must operate under complex conditions for extended periods: they must withstand radial loads of 5-15kN and alternating axial impacts, adapt to a wide speed range of 1500-3000r / min, and cope with extreme environmental temperature differences from -40℃ to 120℃. To improve bearing performance, traditional technologies often employ a single coating to modify the inner and outer raceways of the bearing. Common solutions fall into two main categories, both of which have significant technical shortcomings: One category is high-hardness wear-resistant coatings, such as chrome plating or ordinary diamond-like carbon (DLC) coatings. These coatings can achieve a hardness of HV1500 or higher and a friction coefficient as low as 0.01-0.02, effectively reducing raceway wear. However, these coatings have a high elastic modulus and poor ductility, offering almost no vibration damping capability. During bearing operation, the rigid contact between the balls and the raceway generates high-frequency noise of 65-75 dB, and the coating is prone to cracking and peeling under thermal cycling conditions. The other category is elastic damping coatings, such as pure polyurethane coatings. These coatings can achieve an elongation at break of over 300%, absorbing some vibration impact. However, they suffer from insufficient wear resistance, with raceway wear reaching 0.05 mm / 1000 hours. The actual service life of the bearing typically does not exceed 8000 hours, far from meeting the durability requirements of over 10000 hours for automotive transmission systems.

[0003] Besides the inherent limitations of coating systems, the traditional connection methods between automotive bearings and their mounting bases further restrict overall performance. Existing bearings are mostly assembled to their mounting bases using rigid interference fits or bolt fastening. This connection structure cannot prevent the vibrations generated during bearing operation from being transmitted to the vehicle body. This not only amplifies the vehicle's NVH (noise, vibration, and harshness) problems, affecting ride comfort, but also leads to stress concentration at the contact points between the mounting base and the bearing outer ring. Under long-term alternating loads, this can easily cause secondary failures such as mounting base deformation and bearing outer ring wear. Furthermore, traditional bearing lubrication systems rely heavily on external grease application, lacking built-in grease reservoirs. Under high-speed operating conditions, grease is prone to loss and drying, further accelerating bearing wear and shortening service life.

[0004] Current industry solutions largely focus on optimizing a single performance dimension or making only localized improvements to coating materials and mating methods, failing to establish a synergistic design system encompassing "coating modification + structural adaptation + lubrication enhancement." Neither single wear-resistant coatings nor elastic damping coatings can simultaneously meet the core requirements of "high wear resistance, low noise, and long lifespan." Furthermore, rigid connections and simple lubrication schemes further constrain the overall performance of bearings. Therefore, developing an automotive bearing structure capable of achieving synergistic improvements in multiple performance aspects has become a pressing technical challenge for the industry. Summary of the Invention

[0005] The present invention aims to provide a layered composite coating for automotive bearings to reduce vibration and wear, thereby solving the problem that traditional automotive bearing coatings cannot simultaneously achieve both wear resistance and vibration reduction.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a layered composite coating shock-absorbing and wear-resistant bearing for automobiles, comprising an inner ring, an outer ring, balls, a cage, and an elastic bushing, wherein the outer surface of the inner ring and the inner surface of the outer ring are both provided with a layered composite coating; the layered composite coating consists of a nickel-phosphorus alloy underlayer, a polyurethane-nano silica composite intermediate layer, and a diamond-like carbon surface layer from the substrate outwards; the elastic bushing is embedded between the outer ring and the external mounting base.

[0007] Preferably, as an improvement, the nickel-phosphorus alloy substrate has a thickness of 5-8 μm, is prepared by chemical plating, has a phosphorus content of 8%-12%, and has a bonding strength with the substrate ≥60 MPa.

[0008] Preferably, as an improvement, the thickness of the polyurethane-nano silica composite interlayer is 10-15 μm, wherein the nano silica particle size is 50-100 nm, the mass percentage is 15%-20%, and the elongation at break is ≥400%.

[0009] Preferably, as an improvement, the diamond-like surface layer has a thickness of 2-3 μm, is prepared by magnetron sputtering, has a hardness ≥ HV2000, and a coefficient of friction ≤ 0.008.

[0010] Preferably, as an improvement, the elastic bushing is made of hydrogenated nitrile rubber with a Shore A hardness of 65-70 and a compression set of ≤20%.

[0011] Preferably, as an improvement, the inner surface of the elastic bushing is provided with an axial groove, the groove being 2-3 mm wide and 1-1.5 mm deep, for storing grease.

[0012] Preferably, as an improvement, the ball is made of GCr15SiMn bearing steel, which has been carburized and quenched, with a surface hardness of HRC60-62 and a roundness error of ≤0.5μm.

[0013] Preferably, as an improvement, the cage is made of glass fiber reinforced nylon 66 material, with the reinforcing fiber accounting for 30%-35% of the mass and a heat distortion temperature ≥220℃.

[0014] Preferably, as an improvement, the porosity of the layered composite coating is ≤1%, and the salt spray resistance is ≥1000h.

[0015] Preferably, as an improvement, the contact stress between the inner ring and the ball is ≤2800MPa, and the interference fit between the outer ring and the elastic bushing is 0.02-0.04mm.

[0016] Advantages of this solution: 1. Synergistic achievement of high wear resistance and excellent vibration reduction, improving operational quietness. This invention solves the technical contradiction of traditional automotive bearing coatings in achieving both wear resistance and vibration reduction through a layered composite coating on the outer surface of the inner ring and the inner surface of the outer ring, combined with an elastic bushing between the outer ring and the mounting seat. The diamond-like carbon surface layer has a hardness ≥ HV2000 and a coefficient of friction ≤ 0.008, effectively improving raceway wear resistance; the polyurethane-nano silica composite intermediate layer has a breaking elongation ≥ 400%, combined with a ShoreA hardness 65-70 hydrogenated nitrile rubber elastic bushing, effectively buffering vibration and blocking vibration transmission, ultimately reducing bearing operating noise by 8-12 dB, significantly optimizing the overall vehicle's operational quietness.

[0017] 2. Enhanced overall bearing durability and extended service life: The nickel-phosphorus alloy underlayer has a bonding strength of ≥60MPa with the substrate, ensuring that the layered composite coating does not peel off or crack after 1000 cycles of thermal cycling from -40℃ to 120℃, thus ensuring the coating's long-term effectiveness. The axial grooves on the inner surface of the elastic bushing can store grease, ensuring the bearing's lubrication stability. Meanwhile, the balls are made of GCr15SiMn bearing steel, carburized and quenched, with a surface hardness of HRC60-62 and a roundness error of ≤0.5μm. The cage is made of 30%-35% glass fiber reinforced nylon 66 with a heat distortion temperature of ≥220℃. The synergistic effect of these components increases the overall bearing service life by more than 40%, reducing the frequency of subsequent maintenance.

[0018] 3. Enhanced adaptability to operating conditions and guaranteed performance stability: The layered composite coating has a porosity of ≤1% and a salt spray resistance of ≥1000h, enabling it to withstand complex corrosive environments; the elastic bushing has a compression permanent deformation rate (100℃×70h) of ≤20%, providing excellent resistance to high-temperature aging; the contact stress between the inner ring and the ball is ≤2800MPa, and the interference fit between the outer ring and the elastic bushing is controlled at 0.02-0.04mm, allowing the bearing to adapt to the load and assembly requirements of automotive transmission systems and maintain stable operating performance under various operating conditions.

[0019] 4. Optimize structural adaptability and lower application threshold. The elastic bushing is directly embedded in the gap between the outer ring and the mounting seat. Its elasticity can compensate for the small dimensional errors of the mounting seat and avoid stress concentration caused by rigid fit. The specifications of each bearing component are adapted to the conventional assembly requirements of automotive transmission systems. It can directly replace the same model of traditional bearing without modifying the installation structure, combining assembly convenience and system compatibility. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the inner ring and the layered composite coating of the present invention.

[0021] The reference numerals in the accompanying drawings include: inner ring 1, ball 2, cage 3, outer ring 4, elastic bushing 5, nickel-phosphorus alloy bottom layer 6, polyurethane-nano silica composite intermediate layer 7, and diamond-like carbon surface layer 8. Detailed Implementation

[0022] The following detailed description illustrates the specific implementation method: The basic implementation examples are as follows: Figure 1 -Appendix Figure 2 As shown: A layered composite coating shock-absorbing and wear-resistant bearing for automobiles, with both the inner ring 1 and the outer ring 4 made of GCr15 bearing steel. It undergoes forging (initial forging temperature 1050℃, final forging temperature 850℃), spheroidizing annealing (780℃ for 4 hours), quenching (850℃ for 30 minutes, oil cooling), and low-temperature tempering (180℃ for 2 hours), achieving a final hardness of HRC59 and a dimensional accuracy grade of P5. The inner ring has an inner diameter of φ40mm, the outer ring has an outer diameter of φ68mm, and a width of 15mm.

[0023] A layered composite coating is sequentially prepared on the outer surface of inner ring 1 and the inner surface of outer ring 4, with the parameters of each layer as follows: Nickel-phosphorus alloy underlayer 6: A chemical plating process was used. The plating bath composition was 25 g / L nickel sulfate, 30 g / L sodium hypophosphite, 15 g / L sodium acetate, and 10 g / L trisodium citrate. The plating bath temperature was 88℃, pH 4.8, and the plating time was 90 min, resulting in a final coating thickness of 6 μm. A pull-out test showed a bonding strength of 65 MPa; X-ray fluorescence spectroscopy revealed a phosphorus content of 10%.

[0024] Polyurethane-nano silica composite intermediate layer 7: Nano silica particles with a diameter of 80 nm are mixed with a waterborne polyurethane emulsion with a solid content of 35% at a mass ratio of 18:82, and 0.5% silane coupling agent KH550 is added. An air spraying process is used, with a spray gun pressure of 0.4 MPa and a spraying distance of 200 mm. After spraying, it is cured in an oven at 85℃ for 2 hours, resulting in a final coating thickness of 12 μm. Tensile testing shows an elongation at break of 420% and a Shore hardness of A85.

[0025] Diamond-like carbon (DLC) surface layer 8: A medium-frequency magnetron sputtering system was used, with 99.99% pure high-purity graphite as the target material. The sputtering gases were acetylene and argon at a flow ratio of 1:5, and the vacuum level was 5 × 10⁻⁶. - The sputtering power was 320W, the bias voltage was 150V, the deposition time was 60min, and the final coating thickness was 2.5μm. Nanoindentation test showed a hardness of HV2200; tribological test (dry friction conditions, load 5N, speed 500r / min) showed a friction coefficient of 0.007.

[0026] The elastic bushing 5 is made of hydrogenated nitrile rubber, with 20% carbon black reinforcing agent and 3% antioxidant 4010NA added. It is manufactured by intensive mixing (holding at 150℃ for 10 min) and compression molding vulcanization (holding at 170℃ for 15 min). The dimensions are inner diameter φ68mm, outer diameter φ75mm, width 15mm, and Shore A hardness 68. After a 100℃×70h hot air aging test, the tensile strength retention rate is 92%, and the compression set is 18%. The inner surface has 6 evenly distributed axial grooves 9, with a width of 2.5mm and a depth of 1.2mm. The grooves are filled with lithium-based grease (dropping point 185℃, cone penetration 280 (0.1mm)).

[0027] Ball 2 is made of GCr15SiMn bearing steel, with a diameter of 8mm. It has undergone carburizing treatment (holding at 920℃ for 4h), quenching (holding at 840℃ for 20min and oil cooling) and low-temperature tempering (holding at 160℃ for 3h). The surface hardness is HRC61, the roundness error is 0.4μm, and the surface roughness is Ra0.02μm.

[0028] The cage 3 is made of 30% glass fiber reinforced nylon 66 and manufactured through injection molding. During injection molding, the barrel temperature is set to 260℃ and the mold temperature is maintained at 80℃. The cage 3 has 12 pockets with a clearance of 0.15mm between them and the balls 2, which can precisely limit the position of the 12 balls 2 and prevent the balls from shifting or colliding during operation. The cage 3 has been tested and found to have a heat distortion temperature of ≥225℃ under a load of 1.8MPa, which can adapt to the high-temperature conditions of automotive transmission systems. Its high fiber content structure can ensure the structural stability during long-term operation and will not deform or break due to high-speed friction or load impact.

[0029] The bearing is equipped with 10 fluororubber double-lip seals at both ends, with an interference fit of 0.1 mm and a sealing contact pressure of 0.3 MPa.

[0030] Implementation of testing process and results The bearing of this embodiment and a traditional single-DLC coated bearing (control group, with identical structure except for a single-layer DLC coating, 2μm thick, and HV2000 hardness) were respectively installed on the output shaft of a compact car transmission (CVT-7 speed). The test conditions were: radial load 10kN, axial load 3kN, speed 2000r / min, and ATF transmission fluid (temperature 80℃). The bearings were run continuously for 5000 hours, and environmental adaptability and reliability tests were also performed. The test data are shown in the table below.

[0031] Based on the above systematic test data, it can be seen that the bearing in this embodiment achieves a comprehensive breakthrough in core performance through the synergistic design of a layered composite coating (nickel-phosphorus alloy bottom layer + polyurethane-nano silica intermediate layer + diamond-like carbon surface layer) and a hydrogenated nitrile rubber elastic bushing: noise is reduced by 12-13 dB(A) at different speeds compared to traditional single-DLC coated bearings; the wear of the raceways within 5000 hours is only 22.9% of the control group; rated life is increased by 42.0%; and it maintains stable performance without functional degradation or structural damage in 1000 cycles of thermal cycling, 1500 hours of neutral salt spray, and 100,000 impact load tests. Its innovative coating structure not only solves the technical pain point of traditional bearings in "difficulty in balancing wear resistance and vibration reduction," but also enhances environmental adaptability and reliability, perfectly matching the stringent requirements of automotive transmission systems for low noise, long life, and high stability, and possesses significant technical advantages and practical application value.

[0032] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A layered composite coating vibration-damping and wear-resistant bearing for automobiles, characterized in that: It includes an inner ring, an outer ring, balls, a cage, and an elastic bushing. The outer surface of the inner ring and the inner surface of the outer ring are both provided with a layered composite coating. The layered composite coating consists of a nickel-phosphorus alloy bottom layer, a polyurethane-nano silica composite intermediate layer, and a diamond-like carbon surface layer from the substrate outward. The elastic bushing is embedded between the outer ring and the external mounting base.

2. The automotive layered composite coating shock-absorbing and wear-resistant bearing according to claim 1, characterized in that: The nickel-phosphorus alloy substrate has a thickness of 5-8 μm, is prepared by chemical plating, has a phosphorus content of 8%-12%, and has a bonding strength with the substrate ≥60 MPa.

3. The automotive layered composite coating shock-absorbing and wear-resistant bearing according to claim 2, characterized in that: The thickness of the polyurethane-nano silica composite intermediate layer is 10-15 μm, wherein the nano silica particle size is 50-100 nm, the mass percentage is 15%-20%, and the elongation at break is ≥400%.

4. The automotive layered composite coating shock-absorbing and wear-resistant bearing according to claim 3, characterized in that: The diamond-like carbon surface layer has a thickness of 2-3 μm, is prepared by magnetron sputtering, has a hardness ≥ HV2000, and a coefficient of friction ≤ 0.

008.

5. The automotive layered composite coating shock-absorbing and wear-resistant bearing according to claim 4, characterized in that: The elastic bushing is made of hydrogenated nitrile rubber with a Shore A hardness of 65-70 and a compression set of ≤20%.

6. The automotive layered composite coating shock-absorbing and wear-resistant bearing according to claim 5, characterized in that: The inner surface of the elastic bushing is provided with an axial groove, the groove being 2-3 mm wide and 1-1.5 mm deep, for storing grease.

7. The automotive layered composite coating shock-absorbing and wear-resistant bearing according to claim 6, characterized in that: The ball is made of GCr15SiMn bearing steel, which has been carburized and quenched, with a surface hardness of HRC60-62 and a roundness error of ≤0.5μm.

8. The automotive layered composite coating shock-absorbing and wear-resistant bearing according to claim 7, characterized in that: The cage is made of glass fiber reinforced nylon 66, with the reinforcing fiber accounting for 30%-35% of the mass, and the heat distortion temperature is ≥220℃.

9. The automotive layered composite coating shock-absorbing and wear-resistant bearing according to claim 8, characterized in that: The porosity of the layered composite coating is ≤1%, and its salt spray resistance is ≥1000h.

10. The automotive layered composite coating shock-absorbing and wear-resistant bearing according to claim 9, characterized in that: The contact stress between the inner ring and the ball is ≤2800MPa, and the interference fit between the outer ring and the elastic bushing is 0.02-0.04mm.

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