Magnetorheological damper

Abstract

The utility model discloses a magnetorheological damper. The magneto-rheological damper comprises a graphene composite coating which is coated on the magneto-rheological damper. After the graphene composite coating is formed on the structural surface of the magneto-rheological damper, the heat radiation performance of the surface of the magneto-rheological damper is directly improved, the heat dissipation efficiency of the magneto-rheological damper is remarkably improved, the temperature of damper equipment is effectively reduced, and the service life of the magneto-rheological damper is prolonged; particularly, the application scene of the magnetorheological damper is special, for example, the application space is narrow, and a large radiator is difficult to increase.

Description

Technical Field

[0001] The utility model relates to the technical field of magnetorheological fluid, in particular to a magnetorheological damper coated with a graphene composite coating. Background Art

[0002] Magnetorheological technology and equipment are experiencing massive growth in both technology and application globally and in China. Magnetorheological dampers, using magnetorheological fluid as the working medium, are increasingly being used in military and civilian applications such as automobiles, construction machinery, engineering vehicles, medical devices, seating, and industrial processing and equipment vibration reduction to achieve technical advantages such as vibration reduction, cushioning, noise reduction, and improved vehicle handling and comfort.

[0003] When a magnetorheological damper is operating, its internal magnetorheological fluid and components generate a large amount of heat due to internal components such as coils, friction, and the conversion of mechanical energy into thermal energy. This heat is then transferred to the damper surface through heat conduction. However, due to the low emissivity of metals (less than 0.2), most of the heat accumulates on the surface in a short period of time and cannot be effectively dissipated. If the heat on the surface of the magnetorheological damper cannot be dissipated promptly and effectively, it will cause the temperature inside and outside the magnetorheological damper, especially inside, to rise sharply. This increased temperature not only leads to unstable equipment performance, shortened service life, and reduced equipment reliability, but can also cause the magnetorheological damper to become scrapped and inoperable.

[0004] In particular, when magnetorheological dampers frequently operate under medium and heavy loads, such as in vehicles using magnetorheological electromagnetic suspension, the temperature of the dampers can rise to over 100 degrees Celsius or even higher under certain operating conditions. Therefore, heat dissipation becomes a significant and prominent issue. Suspension systems with magnetorheological dampers, as a crucial component of vehicles, play a vital role in ensuring smoothness, comfort, and stability during driving. However, due to varying road conditions and vehicle speeds during driving, the vehicle suspension system and its magnetorheological dampers must constantly operate, constantly adjusting and adapting to maintain optimal driving conditions. This requires the suspension system to possess a certain degree of adaptability and intelligence. Magnetorheological dampers used in vehicle suspension systems utilize the magnetorheological effect to achieve damping adjustment. They can adjust the damping force in real time by varying the magnetic field strength. These intelligent and adaptable dampers play a positive role in improving vehicle suspension performance, reducing vibration and noise, and extending vehicle life. As people's demand for comfort and control performance increases, the performance standards of magnetorheological dampers, including working stability, reliability, service life, etc., have also been raised to new heights. This trend has made the heat dissipation challenge of magnetorheological dampers increasingly severe.

[0005] Generally speaking, piston-type MR dampers used in medium- and heavy-load applications, such as vehicle suspensions, primarily consist of a piston, a cylinder, and a MR fluid. When the MR damper is operating, the piston reciprocates within the cylinder. By varying the operating current of the excitation coil on the piston rod, the magnetic field strength of the magnetic field circuit is altered, thereby varying the damping force of the MR damper. The operation of the MR damper is often accompanied by a series of energy conversion processes, such as the conversion of electrical energy into magnetic field energy and mechanical energy into internal energy. The internal energy generated by the system is released as heat, causing localized temperature increases in the MR damper. Excessive localized temperature increases in the MR damper can have a variety of negative impacts that directly affect the damper's performance, stability, and service life. For example, elevated temperature reduces the viscosity and yield stress of the MR fluid, diminishes the MR effect, increases thermal stresses between internal components, affecting the overall stability of the damper, accelerates the aging and hardening of seals, and increases the resistance of the electromagnetic coil. Therefore, during use, it is necessary to pay close attention to the temperature and working heat dissipation status of the magnetorheological damper, and take effective heat dissipation and cooling measures to ensure its normal operation and long-term stability.

[0006] In response to the heat dissipation problem of magnetorheological dampers, some people have proposed methods such as installing heat sinks, using heat pipe technology, forced air cooling, optimizing magnetorheological formulas, and improving damper structural design to reduce the local high temperature of the damper. However, there is no related application technology involving the application of coatings to dissipate heat on magnetorheological dampers.

[0007] CN117946559A discloses a method for preparing a heat dissipation coating, comprising the following steps: adding, by percentage, 22%-30% of a resin, 0.25%-4% of a dispersant, 0.05%-0.2% of a defoaming agent, 2%-7% of a cosolvent, 0.5%-5% of graphene, and 55%-68% of water to a container in a certain order to obtain a resin mixture; dispersing the resin mixture using a physical dispersion method to obtain a graphene composite resin slurry; and grinding the graphene composite resin slurry to obtain a heat dissipation coating. The graphene in the heat dissipation coating has reduced graphene agglomeration and has good heat dissipation performance. However, the graphene-containing coating disclosed in CN117946559A is designed for heat dissipation in 5G base stations and is required to have excellent salt spray corrosion resistance. However, this type of heat-dissipating coating is not suitable for effectively dissipating heat from magnetorheological dampers. Given the operating characteristics of magnetorheological dampers, their temperatures rise dramatically and continuously under high-frequency, heavy-load conditions, placing higher performance requirements on heat-dissipating coatings for efficient and rapid heat dissipation. The graphene-containing composite coating disclosed in CN117946559A has an excessively high resin content and a single, low-content graphene heat-dissipating component. Neither its design objectives nor its intended applications are disclosed, and it cannot meet the performance requirements for efficient and rapid heat dissipation in magnetorheological dampers.

[0008] The information included in this background section of the present specification, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not to be construed as subject matter that will limit the scope of the present invention. Utility Model Content

[0009] In view of the above and other more ideas, the present utility model is proposed.

[0010] Aiming at the heat dissipation problem of magnetorheological damper, the utility model designs and prepares a graphene composite coating with high radiation heat dissipation and applies it to the magnetorheological damper structure. It not only has the advantages of simple process, low cost and high space utilization, but also can significantly improve the heat dissipation, reliability, working stability and service life of the magnetorheological damper.

[0011] Specifically, this utility model addresses the heat dissipation issues inherent in magnetorheological dampers by applying a specialized graphene composite coating tailored to the damper's operating conditions to specific components. This coating effectively and rapidly dissipates the heat that rapidly accumulates during operation. Testing of the damper's cooling performance demonstrates that the graphene composite coating significantly reduces heat and temperature, meeting industrial applicability and practical requirements.

[0012] Through the heat dissipation and cooling test of the magnetorheological damper, it is confirmed that the graphene-containing composite coating with high heat dissipation performance of the utility model, when applied to specific components of the magnetorheological damper to form a composite coating structure, has a significant improvement in the heat dissipation of the magnetorheological damper.

[0013] More specifically, according to one aspect of the present invention, a magnetorheological damper is provided, comprising a graphene composite coating coated on the magnetorheological damper.

[0014] According to one embodiment, the graphene composite coating includes graphene dispersed in a resin.

[0015] According to an embodiment, the graphene includes at least one of single-layer graphene, multi-layer graphene, graphene oxide, modified graphene, nanographene, nitrided graphene, and graphene-like materials.

[0016] According to one embodiment, the graphene composite coating further includes at least one composite heat dissipation component selected from silicon carbide, aluminum oxide, boron nitride, aluminum nitride, magnesium oxide, zinc oxide, and diamond powder.

[0017] According to one embodiment, the thickness of the graphene composite coating is in the range of 50-300 microns.

[0018] According to one embodiment, the thickness of the graphene composite coating is in the range of 80-200 microns.

[0019] According to one embodiment, the thickness of the graphene composite coating is in the range of 100-150 microns.

[0020] According to one embodiment, the magnetorheological damper is a piston-type magnetorheological damper, which includes: a cylinder, the cylinder having an inner cavity, in which a magnetorheological fluid is sealed and filled as a working fluid; a piston assembly that reciprocates in the inner cavity, the piston assembly including a piston rod and a piston assembled together, wherein the piston rod extends from one end of the cylinder; and an excitation coil and at least one magnetorheological fluid channel arranged in the piston, wherein the magnetorheological fluid channel connects the inner cavity at both ends of the piston and the magnetorheological fluid therein; wherein the graphene composite coating is coated on the outer surface of the cylinder.

[0021] According to one embodiment, the magnetorheological damper is a magnetorheological rotational damper, which includes: a magnetorheological cavity; a main shaft rotatably installed through the magnetorheological cavity; a damping device fixed on the main shaft and capable of rotating with the main shaft in the magnetorheological cavity; a magnetorheological fluid contained in the magnetorheological cavity; and an excitation coil for generating an excitation magnetic field; wherein the damping device is placed in the magnetorheological fluid; and wherein the graphene composite coating is coated on the outer surface of the magnetorheological cavity.

[0022] According to an embodiment, the piston-type magnetorheological damper is a magnetorheological damper used in vehicles.

[0023] According to an embodiment, the vehicle is a motor vehicle, wherein the piston-type magnetorheological damper is applied to an electromagnetic suspension of a chassis of the motor vehicle.

[0024] According to one embodiment, the magnetorheological damper further includes a heat sink with heat dissipation fins arranged on the cylinder or body of the magnetorheological damper or operably connected to the magnetorheological damper, wherein the graphene composite coating is coated on at least a portion of the cylinder or body and is also coated on the heat dissipation fins of the heat sink.

[0025] According to another aspect of the present invention, the use of applying the graphene composite coating to a magnetorheological damper for heat dissipation is also disclosed.

[0026] According to one embodiment, the graphene composite coating is coated on at least the outer surface of the cylinder or body of the magnetorheological damper to improve its radiative heat dissipation.

[0027] According to one embodiment, the graphene composite coating is further coated on the external heat sink (including its heat dissipation fins) of the magnetorheological damper to improve its radiation heat dissipation.

[0028] According to one embodiment, the graphene composite coating comprises graphene dispersed in a resin, and at least one of silicon carbide, aluminum oxide, boron nitride, aluminum nitride, magnesium oxide, zinc oxide, and diamond powder; wherein the thickness of the graphene composite coating is in the range of 50-300 microns.

[0029] According to another aspect of the present invention, a graphene-containing composite coating suitable for heat dissipation of magnetorheological dampers and a preparation method thereof are disclosed. By adding graphene (such as but not limited to modified graphene oxide) and other types of thermally conductive materials, such as silicon carbide, aluminum oxide, boron nitride, aluminum nitride, magnesium oxide, zinc oxide, diamond powder, etc., to the composite coating, a thermal conductive network is formed in the composite heat dissipation coating finally applied to the magnetorheological damper, thereby achieving the purpose of efficient and rapid heat dissipation. At the same time, the present invention also proposes to add a water-based acrylic resin and a polyurethane resin to the composite coating in a certain proportion, and to add silicon dioxide to obtain a composite coating with high hardness and high adhesion, so that the obtained composite coating not only has efficient heat dissipation, but also has a surface that is more scratch-resistant and rub-resistant.

[0030] According to another aspect of the present invention, a graphene composite coating for a magnetorheological damper is disclosed, comprising the following ingredients in parts by weight: 1-5 parts of graphene; 0.5-4 parts in total of at least one of silicon carbide, aluminum oxide, boron nitride, aluminum nitride, magnesium oxide, zinc oxide, and diamond powder; 0.25-1 part of sodium lauryl sulfate; 10-40 parts of water-based acrylic resin; 10-40 parts of polyurethane resin; 1-4 parts of dispersant; 1-4 parts of film-forming aid; 0.5-3 parts of cross-linking agent; 1-4 parts of defoaming agent; and the balance being water.

[0031] According to one embodiment, the graphene composite coating further comprises 0.5-2 parts by weight of silicon dioxide.

[0032] According to one embodiment, the graphene includes at least one of single-layer graphene, multi-layer graphene, graphene oxide, modified graphene, nanographene, nitrided graphene, and graphene-like materials.

[0033] According to one embodiment, the graphene is modified graphene oxide.

[0034] According to one embodiment, the dispersant is VOK-4950, which can be selected from the following four dispersants: VOK-Disper 41000, VOK-4950, VOK-7050 and Sago-9780; the film-forming aid is dipropylene glycol butyl ether, which can be selected from dipropylene glycol butyl ether and diethylene glycol propyl ether; the cross-linking agent is butanol, which can be selected from butanol and butanediol; and the defoaming agent is AFE-1247, which can be selected from AFE-1247, AFE-168, AFE-7610 and AFE-1267.

[0035] According to another aspect of the present invention, a method for preparing a graphene composite coating for a magnetorheological damper is also disclosed, the method comprising the following steps: a. dissolving 1-3 parts of graphene in 30-50 parts of deionized water, and ultrasonically dispersing for 1 hour to form a stable dispersion; b. adding 0.5-4 parts of at least one of silicon carbide, aluminum oxide, boron nitride, aluminum nitride, magnesium oxide, zinc oxide, and diamond powder, and 0.25-1 part of sodium lauryl sulfate to the dispersion obtained in step a, and magnetically stirring for 0.5-2 hours to form a mixed solution; c. adding 10-40 parts of A water-based acrylic resin and 10-40 parts of a polyurethane resin are mechanically stirred for 1-3 hours, and then added to the mixed solution of step b and stirred evenly. d. 1-4 parts of a dispersant, 1-4 parts of a film-forming aid, 0.5-3 parts of a cross-linking agent, and 1-4 parts of a defoaming agent are added to the solution obtained in step c and stirred evenly. e. The solution obtained in step d is placed in a ball mill and ball-milled at a speed of 800-1000 rpm for 1-2 hours. After filtering through a 300-mesh filter, the filtrate is placed in an ultrasonic oscillator and vibrated for 0.5 hours. The final slurry obtained is the graphene composite coating for magnetorheological dampers.

[0036] According to one embodiment, the method further comprises adding 0.5-2 parts by weight of silicon dioxide in step b.

[0037] According to one embodiment, the graphene includes at least one of single-layer graphene, multi-layer graphene, graphene oxide, modified graphene, nanographene, nitrided graphene, and graphene-like materials.

[0038] According to one embodiment, the dispersant is VOK-4950, which can be selected from the following four dispersants: VOK-Disper 41000, VOK-4950, VOK-7050 and Sago-9780; the film-forming aid is dipropylene glycol butyl ether, which can be selected from dipropylene glycol butyl ether and diethylene glycol propyl ether; the cross-linking agent is butanol, which can be selected from butanol and butanediol; and the defoaming agent is AFE-1247, which can be selected from AFE-1247, AFE-168, AFE-7610 and AFE-1267.

[0039] According to one embodiment, the weight ratio of the water-based acrylic resin to the polyurethane resin is in a range of 1:2 to 2:1.

[0040] In one embodiment of the preparation method of the graphene-containing composite coating according to the utility model, a ball mill is used for high-speed milling to reduce the size of the heat dissipation particles so as to obtain a coating with smaller particles. The surface of the composite coating obtained after spraying is smoother and has higher adhesion. The method may include the following steps: a. Add 1-3 parts of modified graphene oxide to 30-50 parts of deionized water, and ultrasonically disperse for 1 hour to form a stable dispersion; b. Add 0.5-2 parts of silicon carbide, 0.5-2 parts of aluminum oxide, and at least one of 0.5-2 parts of silicon dioxide to the dispersion obtained in step a, and then add 0.25-1 part of sodium lauryl sulfate, and stir magnetically to form a mixed solution; c. Add 10-40 parts of water-based acrylic resin and 10-40 parts of polyurethane resin to the mixed solution described in step b after mechanical mixing in a special proportion, and stir the mixed solution in a mechanical stirrer for 1-3 hours; d. Add the mixture obtained in step c At least one of 1-4 parts of a dispersant, 1-4 parts of a film-forming aid, 0.5-3 parts of a cross-linking agent, and 1-4 parts of a defoaming agent is added to the solution and stirred evenly; e. the solution obtained in step d is placed in an ultrasonic oscillator and oscillated for 0.25-2 hours to obtain an oscillated solution; f. the solution obtained in step e is further magnetically stirred for 0.5-1 hour; and g. the solution obtained in step f is placed in a ball mill and milled at a speed of 800-1000 r / min for 1-2 hours, and then large particles of impurities are filtered out with a 300-mesh filter. The filtered filtrate is placed in an ultrasonic oscillator and oscillated for 0.5-1 hour to obtain a graphene composite coating suitable for heat dissipation of a magnetorheological damper.

[0041] In the above-mentioned method for preparing a graphene composite coating suitable for magnetorheological dampers, the dispersant described in step c may be BYK-110, the film-forming aid may be N,N-dimethylformamide, the cross-linking agent may be isopropyl alcohol, and the defoaming agent may be polydimethylsiloxane.

[0042] In the above-mentioned method for preparing the graphene composite coating suitable for magnetorheological dampers, the stirring time in step b, such as magnetic stirring, can be about 0.5 h to 2 h.

[0043] In the above-mentioned method for preparing the graphene composite coating suitable for magnetorheological dampers, the mechanical stirring time in step c can be about 0.5h-3h.

[0044] In the above-mentioned method for preparing the graphene composite coating suitable for magnetorheological dampers, the stirring time in step d, such as magnetic stirring, can be about 0.5 h to 5 h.

[0045] Compared with the prior art, the technical problems that can be effectively solved and the beneficial effects achieved by the present invention include the following:

[0046] The utility model provides a graphene composite coating for magnetorheological dampers, which has excellent heat dissipation performance, especially fast and efficient high-temperature radiation heat dissipation, and a coating applied on the magnetorheological damper. Due to the addition of well-dispersed, such as modified graphene oxide, and the mixing of other different types of high thermal conductivity powders such as aluminum oxide and silicon carbide, a heat conduction network is formed in the final coating, thereby achieving the purpose of efficient and rapid heat dissipation.

[0047] The graphene composite heat dissipation coating slurry of the present invention is designed to be coated on a magnetorheological damper. The cylinder, cavity or main body of the damper can be, for example, a straight cylinder, and is generally made of steel (ordinary steel, such as 20 steel, or stainless steel, etc.). After coating, the graphene composite heat dissipation coating slurry of the present invention can be tightly combined with the steel material of the cylinder, has strong adhesion, is not easy to fall off even at high temperatures or when heated, and can dissipate heat efficiently and durably.

[0048] After the graphene composite heat dissipation coating of the utility model forms a coating on the structural surface of the magnetorheological damper, it directly and significantly increases the thermal radiation performance and heat dissipation area of the damper surface, significantly improving the heat dissipation efficiency; effectively reduces the temperature of the damper equipment and extends its service life; especially in the special application scenarios of the magnetorheological damper, such as when the application space is small and it is difficult to add a larger radiator, it can solve the technical problem of efficient and rapid heat dissipation in a small space, and improve the operating performance, reliability, life and resistance to higher operating temperatures of the damper; in some specific embodiments, it can help improve the corrosion resistance and scratch resistance of the magnetorheological damper equipment.

[0049] More embodiments of the present invention can also achieve other advantageous technical effects that are not listed one by one. These other technical effects may be partially described below and can be anticipated and understood by those skilled in the art after reading the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The above features and advantages of these embodiments and other features and advantages and the manner in which they are achieved will become more apparent, and embodiments of the present invention may be better understood, by referring to the following description taken in conjunction with the accompanying drawings, in which:

[0051] Figure 1A is an overall picture of an example of a conventional piston-type magnetorheological damper to which no graphene composite coating is applied.

[0052] Figure 1B According to an embodiment of the present invention, Figure 1A The overall picture of an example of a piston-type magnetorheological damper is shown, in which the cylinder of the same piston-type magnetorheological damper is coated with the graphene composite coating of the present invention.

[0053] Figure 2A Under the same working conditions, Figure 1A and Figure 1B The graph shows a comparison of the working time of two piston-type magnetorheological dampers at multiple identical temperature values.

[0054] Figure 2B Under the same working conditions, Figure 1A and Figure 1B The graph shows a comparison of the number of normal cycles required for two piston-type magnetorheological dampers to reach multiple temperature values.

[0055] Figure 3 This is a schematic diagram of the test data and comparison curves of the dynamic equilibrium temperature of a C50 piston-type magnetorheological damper with a graphene composite coating and a C50 piston-type magnetorheological damper without a coating under low working current conditions under the same working conditions.

[0056] Figure 4 The overall schematic diagram of the piston-type magnetorheological damper with no coating applied on the cylinder is further shown.

[0057] Figure 5 The overall schematic diagram of a piston-type magnetorheological damper according to an embodiment of the present invention is further shown, in which the outer surface of the cylinder is coated with the graphene composite coating of the present invention.

[0058] Figure 6 Shown Figure 5 The diagram shows a suitably enlarged schematic longitudinal sectional view of the cylinder of the piston-type magnetorheological damper coated with the graphene composite coating. In particular, for the sake of clarity, the diagram shows the graphene composite coating coated on the outer surface of the cylinder of the piston-type magnetorheological damper in a non-scaled and intentionally enlarged manner. DETAILED DESCRIPTION

[0059] In the following description of the drawings and specific embodiments, details of one or more embodiments of the present invention will be described. From these descriptions, drawings and claims, other features, purposes and advantages of the present invention will be clear.

[0060] It should be understood that the illustrated and described embodiments are not limited in application to the details of the construction and arrangement of the components set forth in the following description or illustrated in the accompanying drawings. The illustrated embodiments may be other embodiments and can be implemented or executed in various ways. Each example is provided in an explanation of the disclosed embodiments, not in a limiting manner. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the various embodiments of the present invention without departing from the scope or essence of the present invention. For example, a feature illustrated or described as part of one embodiment may be used in conjunction with another embodiment to still produce another embodiment. Therefore, the present invention discloses such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0061] Likewise, it is understood that the phrases and terms used herein are for descriptive purposes and should not be considered restrictive. The use of "include," "comprising," or "having" and variations thereof herein is intended to encompass the items listed thereafter and their equivalents as well as additional items.

[0062] The various aspects and embodiments of the present invention will be described in more detail below with reference to specific embodiments of the present invention and with reference to the accompanying drawings.

[0063] Example 1 of a method for preparing a graphene composite coating

[0064] An exemplary preparation process of the graphene composite coating according to Example 1 may include the following steps:

[0065] (1) Add 1-1.5 g of graphene oxide (e.g., graphene oxide numbered XF002-2 produced by Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.) to 50 ml of deionized water and ultrasonically disperse to form a stable dispersion. Then, add 0.5 g of silicon carbide, 0.5 g of aluminum oxide, 0.5 g of silicon dioxide, and 0.1 g of sodium lauryl sulfate, and stir magnetically for 2 h to obtain a mixed solution.

[0066] (2) 15 ml of water-based acrylic resin and 35 ml of polyurethane resin were mechanically stirred for 3 h to mix uniformly, and then added to the mixed solution in step (1), and magnetically stirred for 5 h;

[0067] (3) Add 2 ml BYK VOK-4950, 3 ml dipropylene glycol butyl ether, 3 ml butanol, and 2 ml AFE-1247 to the solution obtained in step (2) and stir evenly;

[0068] (4) The solution obtained in step (3) was then placed in a ball mill for ball milling, stirred at a speed of 800-1000 r / min for 1 hour, and then large particles of impurities were filtered out with a 300-mesh filter. The filtrate was then placed in an ultrasonic oscillator for 0.5 hours to finally obtain the target graphene composite coating in the form of a slurry.

[0069] In industrial production, by preparing and providing the components of the graphene composite coating according to the above proportions and performing the operations according to the above steps, a batch-produced graphene composite coating product in the form of a slurry can be obtained.

[0070] Example 2 of the preparation method of graphene composite coating

[0071] An exemplary preparation process of the graphene composite coating according to Example 2 may include the following steps:

[0072] (1) Add 2-2.5 g of graphene oxide (e.g., graphene oxide numbered XF002-2 produced by Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.) to 50 ml of deionized water and ultrasonically disperse to form a stable dispersion. Then, add 1 g of silicon carbide, 0.5 g of aluminum oxide, 0.5 g of silicon dioxide, and 0.1 g of sodium lauryl sulfate and stir magnetically to form a mixed solution.

[0073] (2) 20 ml of water-based acrylic resin and 30 ml of polyurethane resin were mechanically stirred for 3 h to mix uniformly, and then added to the mixed solution in step (1), and magnetically stirred for 5 h;

[0074] (3) Add 2 ml BYK VOK-4950, 3 ml dipropylene glycol butyl ether, 3 ml butanol, and 2 ml AFE-1247 to the solution obtained in step (2) and stir evenly;

[0075] (4) The solution obtained in step (3) was then placed in a ball mill for ball milling, stirred at a speed of 800-1000 r / min for 1 hour, and then large particles of impurities were filtered out with a 300-mesh filter. The filtrate was then placed in an ultrasonic oscillator for 0.5 hours to finally obtain the target graphene composite coating in the form of a slurry.

[0076] In industrial production, by preparing and providing the components of the graphene composite coating according to the above proportions and performing the operations according to the above steps, a batch-produced graphene composite coating product in the form of a slurry can be obtained.

[0077] Example 3 of the preparation method of graphene composite coating

[0078] An exemplary preparation process of the graphene composite coating according to Example 3 may include the following steps:

[0079] (1) 3 g of graphene oxide (e.g., graphene oxide numbered XF002-2 produced by Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.) was added to 50 ml of deionized water and ultrasonically dispersed to form a stable dispersion. 0.5 g of silicon carbide, 1 g of aluminum oxide, 1 g of silicon dioxide, and 0.1 g of sodium lauryl sulfate were then added and magnetically stirred to form a mixed solution.

[0080] (2) 30 ml of water-based acrylic resin and 20 ml of polyurethane resin were mechanically stirred for 3 h to mix uniformly, and then added to the mixed solution in step (1), and magnetically stirred for 5 h;

[0081] (3) Add 2 ml BYK VOK-4950, 3 ml dipropylene glycol butyl ether, 3 ml butanol, and 2 ml AFE-1247 to the solution obtained in step (2) and stir evenly;

[0082] (4) The solution obtained in step (3) was then placed in a ball mill for ball milling, stirred at a speed of 800-1000 r / min for 1 hour, and then large particles of impurities were filtered out with a 300-mesh filter. The filtrate was then placed in an ultrasonic oscillator for 0.5 hours to finally obtain the target graphene composite coating in the form of a slurry.

[0083] In industrial production, by preparing and providing the components of the graphene composite coating according to the above proportions and performing the operations according to the above steps, a batch-produced graphene composite coating product in the form of a slurry can be obtained.

[0084] Those skilled in the art will appreciate that the graphene used in the graphene composite coating of the present invention can be in various forms, including single-layer graphene, multi-layer graphene, graphene oxide, modified graphene, nanographene, nitrided graphene, and graphene-like materials. Considering industrial applicability, cost, stable and controllable chemical properties, good solubility, corrosion resistance, and corrosion resistance, graphene oxide is a preferred embodiment in the present invention. For example, single-layer graphene oxide with a thickness of 6-10 nm and a sheet size of 100-200 mesh, as well as certain specific modified graphene oxides, can be used. In the present invention, the primary consideration for modifying the modified graphene is to improve its hydrophilicity and solubility.

[0085] Those skilled in the art will appreciate that, in addition to adding silicon carbide and / or aluminum oxide as composite heat dissipation particles, other or alternative particles with good stability may also be added as composite heat dissipation particles, such as boron nitride, aluminum nitride, magnesium oxide, zinc oxide, aluminum oxide, diamond powder, etc., all of which fall within the scope of the present invention. In the graphene composite coating of the present invention, the addition of silicon dioxide is optional but not essential, and its main function is to enhance the scratch resistance of the coating. Other types of wear-resistant and anti-friction powders are also optional.

[0086] Examples of graphene composite coatings applied to magnetorheological dampers

[0087] An embodiment of applying the graphene composite coating of the present invention to a magnetorheological damper to form a graphene composite coating will be described below with reference to the accompanying drawings.

[0088] Figure 1A is an overall picture of an example of a conventional piston-type magnetorheological damper to which no graphene composite coating is applied. Figure 4 The overall schematic diagram of the piston-type magnetorheological damper with no coating applied on the cylinder is further shown.

[0089] The inventor of the present utility model first proposed to apply the above-mentioned graphene composite coating to a magnetorheological damper to form a graphene composite coating, so as to improve the heat dissipation of the magnetorheological damper.

[0090] Magnetorheological dampers, such as those used in vehicles such as electromagnetic suspensions of vehicle chassis, generally refer to piston-type magnetorheological dampers, such as Figure 1A and Figure 4 As shown. This type of piston-type magnetorheological damper 1 generally includes: a cylinder 10, the cylinder having an inner cavity, in which magnetorheological fluid is sealed and filled as a working fluid; a piston assembly that reciprocates in the inner cavity, the piston assembly including a piston rod and a piston fixedly assembled together, wherein the piston rod extends from one end of the cylinder; an excitation coil and at least one magnetorheological fluid channel provided in the piston, wherein the magnetorheological fluid channel connects the inner cavity at both ends of the piston and the magnetorheological fluid therein. Both ends of the cylinder are sealed; and a floating piston may be provided on the side of the inner cavity opposite to the piston rod, and a high-pressure gas chamber is also provided at the end of the piston-type magnetorheological damper close to the floating piston for buffering. For examples of piston-type magnetorheological dampers, for example, but not limited to, please refer to the utility model patent "Piston-type magnetorheological damper" with application number 202223006989.6 applied by the applicant on November 11, 2022, and the piston-type magnetorheological damper disclosed in the utility model patent "Seated chest press trainer equipped with magnetorheological damper" with application number 202223116891.6 applied by the applicant on November 23, 2022. The contents related to piston-type magnetorheological dampers in these patents are incorporated into this application by reference, just as if directly described in this application.

[0091] Magnetorheological dampers, such as those used in electromagnetic suspension systems for vehicle chassis, typically operate in temperatures between -50°C and 50°C. After a period of operation, the damper's cylinder temperature typically reaches approximately 90°C. Under heavy loads and high-frequency continuous operation, the temperature can reach as high as 90-130°C, or even as high as 90-150°C. It is generally considered normal and acceptable for a damper's cylinder temperature to remain below approximately 90°C, for example, around 70-90°C or lower, after a period of operation. However, if the damper's cylinder temperature remains excessively high for an extended period, it can negatively impact the damper's performance, stability, and lifespan. In extreme cases, it can even cause the damper to cease functioning properly. Therefore, improving the rapid heat dissipation performance of MR dampers is an ongoing and pressing need within the industry.

[0092] The graphene composite coating prepared according to the utility model is sprayed on a surface such as Figure 1A A graphene composite coating 11 is formed on the piston-type magnetorheological damper of the same type as shown in FIG. Figure 1B and Figure 5 shown. Figure 1B According to an embodiment of the present invention, Figure 1A The overall picture of an example of a piston-type magnetorheological damper is shown, in which the cylinder 10 of the same piston-type magnetorheological damper 1 is coated with the graphene composite coating 11 of the present invention. Figure 5 The overall schematic diagram of a piston-type magnetorheological damper 1 according to an embodiment of the present invention is further shown, in which the outer surface of the cylinder 10 is coated with the graphene composite coating 11 of the present invention.

[0093] Figure 6 It shows Figure 5 The diagram shows a suitably enlarged schematic longitudinal sectional view of the cylinder 10 of the piston-type magnetorheological damper coated with the graphene composite coating 11. In particular, for the sake of clarity, the diagram shows the graphene composite coating 11 coated on the outer surface of the cylinder 10 of the piston-type magnetorheological damper in a non-scaled and intentionally enlarged manner.

[0094] According to the existing public technical information and test data, the surface (heat) emissivity of the cylinder 10 (steel cylinder) of the magnetorheological damper and the graphene composite coating 11 of the present invention are shown in Table 1 below. As shown in Table 1, the surface emissivity of the graphene composite coating 11 is ≥0.95, which is much higher than the surface emissivity of the steel cylinder 10 (about 0.1). Therefore, coating the steel cylinder 10 with the graphene composite coating 11 can significantly improve the surface thermal radiation. In other words, the graphene composite coating 11 can allow heat to be radiated and dissipated more quickly from the outer surface of the steel cylinder 10. Nevertheless, on the other hand, the thermal conductivity of the graphene composite coating 11 is lower than that of the steel cylinder 10, that is, the thermal conductivity of the graphene composite coating 11 is inferior to that of the cylinder (steel cylinder). Therefore, the thickness of the graphene composite coating 11 cannot be too thick, otherwise it will affect the heat conduction from the inside to the outside of the magnetorheological damper 1.

[0095] Table I Thermal conductivity and surface emissivity of different materials

[0096] Material Surface emissivity steel cylinder 0.1 Graphene composite coating ≥0.95

[0097] The thicker the graphene composite coating 11, the higher its surface emissivity, but the thermal conductivity will be reduced. Therefore, it is necessary to select an appropriate thickness of the graphene composite coating 11 to achieve a balance between the surface thermal radiation effect and the thermal conductivity effect of the magnetorheological damper. In this regard, the inventors of the present invention have found through extensive practice and testing that the thickness of the graphene composite coating 11 coated on the outer surface of the magnetorheological damper cylinder 10 is acceptable within the range of 50-300 microns, preferably within the range of 80-200 microns, and more preferably within the range of 100-150 microns. This can significantly improve the surface radiation heat dissipation effect of the cylinder 10 without substantially affecting the internal-external thermal conductivity of the damper.

[0098] Although the above description is combined with the coating of a graphene composite coating on the outer surface of the magnetorheological damper cylinder to improve the heat dissipation of the magnetorheological damper, it is fully understood by those skilled in the art that the present invention is not limited to coating the graphene composite coating on the outer surface of the magnetorheological damper cylinder, but can be coated with the graphene composite coating of the present invention in an optional or additional manner on other required components / structures of the magnetorheological damper without affecting the normal operation of the magnetorheological damper, so as to further enhance and improve the heat dissipation effect. For example, in the case where the magnetorheological damper is a magnetorheological rotary damper, the graphene composite coating can also be coated on the outer surface of the cylinder (or magnetorheological cavity or body, etc., that is, the body or cylinder having an inner cavity for accommodating working components such as magnetorheological fluid and excitation coil) of the magnetorheological rotary damper and other required components. For examples of magnetorheological rotational dampers, for example, but not limited to, refer to the magnetorheological damper disclosed in the utility model patent "Magnetorheological Rotational Damper, Electric Power Steering System and Motor Vehicle" with application number 202220528018.9 filed by the present applicant on March 11, 2022. The content related to the magnetorheological rotational damper in the patent is incorporated into this application by reference, just as if directly described in this application.

[0099] Moreover, if a magnetorheological damper (whether it is a piston-type magnetorheological damper, a magnetorheological rotary damper, or other types of magnetorheological dampers or magnetorheological damping vibration reduction / buffering devices) is provided with a heat sink, for example, a heat sink with heat sink fins arranged on (for example, sleeved on) the cylinder of the magnetorheological damper or the magnetorheological cavity / main body (for example, an outer sleeve with a large number of radial heat sink fins, which is arranged on the cylinder or the magnetorheological cavity / main body, for example, approximately in the middle position), the graphene composite coating of the present invention can also be coated on the heat sink and its heat sink fins, etc., all of which are within the scope of the present invention.

[0100] Comparative Experiment 1

[0101] right Figure 1A and Figure 1B The two piston-type magnetorheological dampers shown in Figure 1 were subjected to comparative testing under identical experimental conditions. Heat dissipation performance was measured for both the damper with and without the graphene composite coating. The operating time and number of operating cycles required to reach each temperature were recorded. This allowed for a comparison and assessment of the heat dissipation performance of the magnetorheological damper with and without the graphene composite coating of the present invention applied to the outer surface of the cylinder under the same operating conditions. The comparative testing conditions were as follows.

[0102] Experimental objects: a C50 piston-type magnetorheological damper with the graphene composite coating of the utility model and a C50 piston-type magnetorheological damper without coating.

[0103] Experimental conditions: current 3A, damper stroke 80mm, starting position temperature of room temperature 25℃, damper test speed 100mm / s.

[0104] Experimental equipment: dynamometer test machine.

[0105] Figure 2A Under the same working conditions as above, Figure 1A and Figure 1B The graphs and data show the comparison of the normal working time required for two piston-type magnetorheological dampers to reach multiple temperature values.

[0106] Specifically, if Figure 2A As shown in FIG, the applicant tested the two piston-type magnetorheological dampers under the same working conditions, starting from the outer surface temperature of the cylinder being 30°C, and tested the time required for the outer surface temperature of the piston-type magnetorheological damper cylinder to reach 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C and 150°C respectively. Figure 2A It can be seen that under the same working conditions, for the time spent rising from 30°C to 50°C, 60°C, 70°C, and 80°C, the time spent by the piston-type magnetorheological damper coated with the graphene composite coating and the piston-type magnetorheological damper without the graphene composite coating in each stage of the test is basically the same. This is because when the temperature of the outer surface of the magnetorheological damper cylinder is relatively low, the effect of heat dissipation through radiation from the outer surface does not account for a sufficiently high proportion. Therefore, the cylinder coated with the graphene composite coating does not show any special effect at this time. However, as the temperature of the outer surface of the magnetorheological damper cylinder continues to rise, when it reaches above 90°C (that is, a state where fast and efficient heat dissipation is required), the effect of the outer surface of the magnetorheological damper cylinder at a relatively high temperature dissipating heat through thermal radiation becomes more and more significant. At this time, the graphene composite coating on the outer surface of the magnetorheological damper cylinder exhibits superior thermal radiation heat dissipation capabilities because its surface radiation (heat dissipation) rate is much higher than that of the steel cylinder of the magnetorheological damper. This is reflected in the data and drawings as follows: under the same working conditions, the time taken for the outer surface of the magnetorheological damper cylinder coated with the graphene composite coating to rise from the same relatively low temperature to the same relatively high temperature is longer than that of the magnetorheological damper cylinder without the graphene composite coating. This means that the piston-type magnetorheological damper coated with the graphene composite coating has a better heat dissipation effect than the piston-type magnetorheological damper without the graphene composite coating.

[0107] Figure 2B Under the same working conditions, Figure 1A and Figure 1BThe graph shown is a comparison graph of the normal cycle times (ie, the number of reciprocating motions of the piston of the damper) required for two piston-type magnetorheological dampers to reach multiple temperature values.

[0108] Specifically, if Figure 2B As shown, the applicant tested the two piston-type magnetorheological dampers and tested their normal operation under the same working conditions starting from the outer surface temperature of the cylinder being 30°C, and tested the number of normal cycle operation required for the outer surface temperature of the piston-type magnetorheological damper cylinder to reach 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C and 150°C respectively.

[0109] from Figure 2B It can be seen that under the same working conditions, for the number of cycle operations corresponding to the magnetorheological damper cylinder temperature ranging from 30°C to 50°C, 60°C, 70°C, and 80°C, the number of cycle operations of the piston-type magnetorheological damper coated with the graphene composite coating and the piston-type magnetorheological damper without the graphene composite coating in the tests at each temperature stage is basically the same. This is because when the outer surface temperature of the magnetorheological damper cylinder is relatively low, the effect of heat dissipation through radiation from the outer surface does not account for a sufficiently high proportion. Therefore, at this time, the damper cylinder coated with the graphene composite coating does not show a particularly significant heat dissipation effect. However, as the temperature of the outer surface of the magnetorheological damper cylinder continues to rise, when it reaches above 90°C (that is, a state where fast and efficient heat dissipation is required), the effect of the outer surface of the magnetorheological damper cylinder at a relatively high temperature dissipating heat through thermal radiation becomes more and more significant. At this time, the graphene composite coating on the outer surface of the magnetorheological damper cylinder has a much higher surface radiation (heat dissipation) rate than the steel cylinder of the magnetorheological damper, and therefore exhibits superior thermal radiation heat dissipation capabilities. This is reflected in the data and drawings as follows: under the same working conditions, the outer surface of the magnetorheological damper cylinder coated with the graphene composite coating can perform more cycles of work from the same relatively low temperature to the same relatively high temperature than the magnetorheological damper cylinder without the graphene composite coating. This means that the piston-type magnetorheological damper coated with the graphene composite coating has a better heat dissipation effect than the piston-type magnetorheological damper without the graphene composite coating, because each cycle of work / piston reciprocating motion of the magnetorheological damper generates heat.

[0110] In summary, the above comparative experiment 1 shows that by spraying the graphene composite coating on the steel cylinder of the magnetorheological damper, the magnetorheological damper with the graphene composite coating can work longer and perform more cycles in the same temperature rise range compared with the magnetorheological damper without the coating. This proves that spraying the graphene composite coating on the cylinder of the magnetorheological damper has a significant improvement and enhancement on the rapid heat dissipation and cooling of the magnetorheological damper.

[0111] Comparative Experiment 2

[0112] Test 2.1 Dynamic Equilibrium Temperature Comparison

[0113] The comparative test 2.1 tests the dynamic equilibrium temperature of the magnetorheological damper with and without graphene composite coating under low current.

[0114] The test conditions of the comparative test 2.1 are as follows.

[0115] Experimental objects: a C50 piston-type magnetorheological damper with the graphene composite coating of the utility model and a C50 piston-type magnetorheological damper without coating.

[0116] Experimental conditions: current 0.5A, MR damper stroke 80mm, starting temperature 25℃, MR damper test speed 100mm / s.

[0117] Temperature sampling location: outer surface of the main body (cylinder) of the magnetorheological damper.

[0118] Experimental equipment: dynamometer test machine.

[0119] The dynamic equilibrium temperature of the C50 piston-type magnetorheological damper with graphene composite coating and the C50 piston-type magnetorheological damper without coating under low working current conditions were tested and compared. The test data comparison and curve diagram are as follows: Figure 3 shown.

[0120] Figure 3 The figure is a schematic diagram of the test data and comparison curves of the dynamic equilibrium temperature of the C50 piston type magnetorheological damper with graphene composite coating and the C50 piston type magnetorheological damper without coating under the same working conditions as above. Figure 3 As can be seen from the graph, after 150 minutes of continuous operation at low current, the temperature of the uncoated C50 piston-type MR damper gradually increases from 25°C to approximately 85°C, maintaining a continuous temperature increase during this period. In contrast, under the same operating conditions, after 150 minutes of continuous operation at low current, the temperature of the C50 piston-type MR damper coated with the graphene composite coating according to the present invention remains lower than the temperature of the uncoated C50 piston-type MR damper during the entire 150-minute test period. Furthermore, after gradually increasing from 25°C to approximately 65°C, the operating temperature of the C50 piston-type MR damper coated with the graphene composite coating at low current remains essentially constant, reaching a substantial dynamic equilibrium and stabilizing at approximately 65°C, while the temperature of the uncoated C50 piston-type MR damper continues to rise during the same period.

[0121] The results of test 2.1 clearly show that the graphene composite coating according to the present invention significantly improves the heat dissipation of the magnetorheological damper, especially after the temperature rises to a certain temperature, because its radiation heat dissipation effect is significantly enhanced, the magnetorheological damper, especially the radiation heat dissipation effect, is significantly improved, so that the magnetorheological damper can maintain its temperature no longer rising and achieve a rough dynamic balance when operating at a relatively low current.

[0122] Test 2.2 Static Equilibrium Temperature Comparison

[0123] The comparative test 2.2 tests the static equilibrium temperature of coated and uncoated magnetorheological dampers under low current.

[0124] The test conditions of this comparative test 2.2 are as follows.

[0125] Experimental objects: a C40 piston-type magnetorheological damper with the graphene composite coating of the utility model and a C40 piston-type magnetorheological damper without coating.

[0126] Experimental conditions: currents of 0.5A, 1A, and 3A, and starting temperature of room temperature (25°C).

[0127] Temperature sampling location: outer surface of the main body (cylinder) of the magnetorheological damper.

[0128] Experimental equipment: DC power supply.

[0129] The static equilibrium temperatures of C40 piston dampers with and without a graphene composite coating were tested at different operating currents (0.5A, 1A, and 1.5A). This refers to the temperature at which the damper, operating current alone but without piston reciprocating cycles (static operation), remains. The test results are shown in Table II below.

[0130] Table II Comparison of static equilibrium temperature of coated and uncoated magnetorheological dampers

[0131]

[0132] The results of Test 2.2 clearly demonstrate that the graphene composite coating according to the present invention can effectively reduce the standby (operating) temperature of the magnetorheological damper under different operating currents, even when the magnetorheological damper is only powered (standby) and does not provide cyclic reciprocating buffering operation. The higher the standby temperature, the more significant the heat dissipation effect of the graphene composite coating of the present invention, as shown in Section II above. Obviously, this is because the graphene composite coating of the present invention significantly improves the heat dissipation of the magnetorheological damper, especially after it is raised to a certain temperature, its radiative heat dissipation effect is significantly enhanced, which can more significantly improve the heat dissipation effect of the magnetorheological damper, so that the standby temperature of the magnetorheological damper can be effectively reduced even when the magnetorheological damper is powered (standby) and not operating under different operating currents.

[0133] The foregoing description of several embodiments of the present invention has been presented for illustrative purposes. It is not intended to be exhaustive or to limit the present invention to the precise steps, configurations, and / or forms disclosed. Obviously, many modifications and variations are possible in light of the above teachings. It is intended that the scope of the present invention and all equivalents thereof be defined by the appended claims.

Claims

1. A magnetorheological damper, characterized in that: The magnetorheological damper includes a graphene composite coating coated on the magnetorheological damper.

2. The magnetorheological damper according to claim 1, characterized in that The graphene composite coating comprises graphene dispersed in a resin.

3. The magnetorheological damper according to claim 1, characterized in that: The thickness of the graphene composite coating is in the range of 50-300 microns.

4. The magnetorheological damper according to claim 3, characterized in that: The thickness of the graphene composite coating is in the range of 80-200 microns.

5. The magnetorheological damper according to any one of claims 1 to 4, characterized in that: The magnetorheological damper is a piston-type magnetorheological damper, comprising: a cylinder having an inner cavity, wherein the inner cavity is sealed and filled with a magnetorheological fluid as a working fluid; a piston assembly that reciprocates in the inner cavity, wherein the piston assembly comprises a piston rod and a piston assembled together, wherein the piston rod extends from one end of the cylinder; and an excitation coil and at least one magnetorheological fluid channel disposed in the piston, wherein the magnetorheological fluid channel connects the inner cavities at both ends of the piston and the magnetorheological fluid therein. Wherein, the graphene composite coating is coated on the outer surface of the cylinder.

6. The magnetorheological damper according to any one of claims 1 to 4, characterized in that: The magnetorheological damper is a magnetorheological rotation damper, comprising: a magnetorheological cavity; a main shaft rotatably installed through the magnetorheological cavity; a damping device fixed to the main shaft and capable of rotating together with the main shaft in the magnetorheological cavity; a magnetorheological fluid contained in the magnetorheological cavity; and an excitation coil for generating an excitation magnetic field; wherein the damping device is placed in the magnetorheological fluid; Wherein, the graphene composite coating is coated on the outer surface of the magnetorheological cavity.

7. The magnetorheological damper according to claim 5, characterized in that: The piston-type magnetorheological damper is a magnetorheological damper used in vehicles.

8. The magnetorheological damper according to claim 7, characterized in that: The vehicle is a motor vehicle, wherein the piston-type magnetorheological damper is applied to an electromagnetic suspension of a chassis of the motor vehicle.

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