Wheel unit and vehicle

Abstract

The invention discloses a wheel unit and a vehicle. According to the method, a rim (1) and a spoke (2) are included, the rim (1) and the spoke (2) are connected in a welded mode, the top face of the rim (1) makes contact with a tire bead and a flap respectively, and composite heat insulation coatings (3) are arranged between the top face of the rim (1) and the tire bead and between the top face of the rim (1) and the flap respectively; the composite heat insulation coating (3) comprises a bonding layer (4) sprayed on the top face of the rim (1) and a heat insulation layer (5) sprayed on the bonding layer. The composite heat insulation coating (3) is sprayed on the rim (1), braking heat can be effectively prevented from being transmitted to a tire through the rim (1), the tire burst risk caused by overheat aging of the tire can be avoided, and the service life of the tire is prolonged. And a spraying device does not need to be used for cooling the tire, so that serious pollution to the road environment is avoided, and the driving safety problem caused under the cold condition in winter is avoided.

Description

Technical Field

[0001] The present application relates to the technical field of automobile wheels, and in particular to a wheel unit and a vehicle. Background Art

[0002] Most of the commercial vehicles in my country, especially mining vehicles and slag transport vehicles, use brake drum brakes. The brake drum brake achieves braking through the friction between the brake pads and the brake drum. When the driver steps on the brake pedal, the brake pads are pushed against the inner surface of the brake drum, and the friction between the two converts the vehicle's kinetic energy into heat energy, thereby slowing down or stopping the vehicle. During the braking process, the friction between the brake pads and the brake drum generates a lot of heat, which is transferred to the rim through the axle. Since the rim is in close contact with the tire, the high temperature will also be further transferred to the tire bead area and rubber parts such as the flap and inner tube. Long-term high temperature environment will accelerate the aging process of the tire bead area and rubber parts such as the flap and inner tube, leaving great hidden dangers to vehicle and personal safety.

[0003] In the prior art, the brakes and tires are cooled by installing a water spray device on the vehicle. That is, when braking frequently, the driver operates the control system to start the water pump of the water spray device to extract cooling water from the water tank and transport it to each nozzle through a pipeline. The nozzle is aimed at the heat-generating parts of the brakes and tires for spraying, and the heat is taken away by the evaporation and cooling effect of water, thereby reducing the temperature of the brakes and tires.

[0004] However, when the water spraying device is in use, the water will carry pollutants such as metal particles and rubber debris generated by brake wear and directly discharge to the road surface, causing pollution to the road environment. In addition, in winter, the sprayed water may freeze quickly, causing the road surface to be slippery, seriously affecting driving safety. Summary of the invention

[0005] The embodiments of the present application provide a wheel unit and a vehicle to solve the problem that when cooling the tires by a water spraying device, it is very easy to cause environmental pollution to the road and affect driving safety.

[0006] In a first aspect, an embodiment of the present application provides a wheel unit, comprising: a rim (1) and a spoke (2), wherein the rim (1) and the spoke (2) are connected by welding, the top surface of the rim (1) is in contact with a tire bead and a cushioning strip respectively, and a composite heat-insulating coating (3) is provided between the top surface of the rim (1) and the tire bead, and between the top surface of the rim (1) and the cushioning strip;

[0007] The composite heat-insulating coating (3) comprises: an adhesive layer (4) sprayed on the top surface of the rim and a heat-insulating layer (5) sprayed on the adhesive layer.

[0008] In a possible implementation, the bonding layer (4) is made of NiCrAlY material, and the composition ratio of the NiCrAlY material is nickel Ni: 66%, chromium Cr: 25%, aluminum Al: 8%, and yttrium Y: 1%.

[0009] In a possible implementation, the thickness of the bonding layer (4) is 100 micrometers to 300 micrometers.

[0010] In a possible implementation, the porosity of the bonding layer (4) is 5% to 15%.

[0011] In a possible implementation, the thickness of the heat insulation layer (5) is 200 micrometers to 500 micrometers.

[0012] In a possible implementation, the thermal insulation layer (5) is made of ZrO ceramic material.

[0013] In a possible implementation, the composite thermal insulation coating (3) is sprayed by plasma spraying.

[0014] In a possible implementation, the thermal conductivity of the composite thermal insulation coating (3) is 0.539 W / (m·K).

[0015] In a possible implementation manner, the rim (1) and the spokes (2) are both made of steel.

[0016] In a second aspect, an embodiment of the present application provides a vehicle, comprising a wheel unit provided in the first aspect of the embodiment of the present application.

[0017] The embodiment of the present application provides a wheel unit and a vehicle, wherein a composite heat-insulating coating (3) is provided between the top surface of the rim (1) and the tire bead and between the rim (1) and the cushioning strip, wherein the composite heat-insulating coating (3) comprises a bonding layer (4) sprayed on the top surface of the rim (1) and a heat-insulating layer (5) sprayed on the bonding layer. The bonding layer (4) is sprayed on the surface of the rim (1), thereby improving the mechanical bonding strength between the rim (1) substrate and the heat-insulating layer (5). Under the premise of ensuring the mechanical bonding strength, the heat-insulating performance is improved while the anti-oxidation capacity of the rim (1) substrate is improved by setting a suitable porosity. The heat-insulating layer (5) is made of ZrO ceramic material, which has excellent heat-insulating performance and can effectively prevent the braking heat from being transferred to the tire through the rim (1), thereby slowing down the aging of the tire. The rim (1) of the present application can effectively prevent the braking heat from being transferred to the tire through the rim (1) by spraying the composite heat-insulating coating (3), thereby avoiding the risk of tire blowout caused by tire overheating and aging, thereby improving the service life of the tire. Furthermore, the present application no longer requires the use of a spray device to cool the tires, thereby avoiding serious pollution to the road environment and problems with driving safety in cold winter conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0019] Figure 1 A schematic diagram of the wheel unit structure provided in an embodiment of the present application;

[0020] Figure 2 A schematic diagram for comparing the temperatures of a wheel unit provided in an embodiment of the present application to determine whether the wheel unit contains a composite thermal insulation coating.

[0021] Reference numerals:

[0022] 1- wheel rim; 2- wheel spoke; 3- composite thermal insulation coating; 4- bonding layer; 5- thermal insulation layer.

[0023] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the specific technical solution of the present application will be further described in detail below in conjunction with the drawings in the embodiments of the present application. The following embodiments are used to illustrate the present application, but are not used to limit the scope of the present application.

[0025] In the embodiments of the present application, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more.

[0026] In addition, in the embodiments of the present application, directional terms such as "up", "down", "left" and "right" are defined relative to the orientation of the components in the drawings. It should be understood that these directional terms are relative concepts. They are used for relative description and clarification, and they may change accordingly according to the changes in the orientation of the components in the drawings.

[0027] In the embodiments of the present application, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0028] In the embodiments of the present application, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0029] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0030] In the prior art, a water spraying device is installed on the tire of the vehicle. When frequent braking occurs on the road, the driver needs to manually operate the control system to start the water pump of the water spraying device to extract cooling water from the water tank, and then transport it to each nozzle through a pipeline. The nozzle is aimed at the heating parts of the brake and tire for spraying, and the heat is taken away by the evaporation and cooling effect of water, thereby reducing the temperature of the brake and tire. However, during the use of the spraying device, water will carry pollutants such as metal particles and rubber debris generated by brake wear and be discharged directly onto the road surface, causing pollution to the road environment. Moreover, in cold winter conditions, the sprayed water may freeze quickly, causing the road surface to be slippery, seriously affecting driving safety.

[0031] The wheel unit and vehicle provided by the present application no longer need to install or use a water spraying device to cool the tire, thereby avoiding tire heating and causing tire aging. The present application avoids tire heating and causing tire aging by providing a composite heat-insulating coating (3) between the top surface of the wheel rim (1) and the tire bead, and between the top surface of the rim (1) and the cushioning strip. The composite heat-insulating coating (3) includes a bonding layer (4) sprayed on the top surface of the rim (1) and a heat-insulating layer (5) sprayed on the bonding layer. First, a suitable porosity is set for the bonding layer (4), and the bonding layer (4) is sprayed onto the top surface of the rim (1) by plasma spraying. Since the thermal conductivity of air is much smaller than that of solid materials, the gas in the tiny pores in the bonding layer (4) makes the thermal conductivity very small, and since the gas flow in most of the micropores is restricted, the gas flow speed in the air is very small, and the worse the gas flowability, the smaller the convective heat transfer. Therefore, under the premise of ensuring the mechanical bonding strength between the rim (1) and the heat-insulating layer, the heat-insulating capacity is improved. The thermal conductivity of the ZrO ceramic material used in the heat insulation layer (5) is much lower than that of metal, so it can effectively reduce the transfer of heat from the high temperature area to the low temperature area, that is, reduce the heat transfer from the rim (1) to the tire, thereby reducing the temperature of the tire. In addition, the present application does not require the use of a spray device to cool the tire, thereby avoiding serious pollution to the road environment and the problem of seriously affecting driving safety in cold winter conditions.

[0032] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0033] Figure 1 A schematic diagram of the wheel unit structure provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the wheel unit provided in the embodiment of the present application comprises: a rim (1) and a spoke (2), wherein the rim (1) and the spoke (2) are connected by welding, the top surface of the rim (1) is in contact with the tire bead and the cushioning strip respectively, and a composite heat-insulating coating (3) is provided between the top surface of the rim (1) and the tire bead, and between the top surface of the rim (1) and the cushioning strip.

[0034] In an embodiment of the present application, the wheel unit is composed of a rim (1) and spokes (2), wherein the rim (1) and the spokes (2) are connected together by welding. Optionally, the rim (1) and the spokes (2) can be connected by fasteners such as bolts, or the rim (1) and the spokes (2) can be integrally formed by forging or casting.

[0035] Furthermore, the top surface of the rim (1) contacts the tire bead and the flap respectively. The tire bead is the part of the tire mounted on the rim (1). The tire bead fits tightly on the top surface of the rim (1). The close fit between the tire bead and the rim (1) ensures that the tire can be securely mounted on the wheel. The flap is usually used in tire structures with inner tubes. It is located between the inner tube and the rim (1) to protect the inner tube and seal. The flap will also contact the top surface of the rim (1) to ensure that the inner tube can be securely mounted on the rim (1) and prevent gas leakage. When the vehicle is running, the tire bead and the flap will be subjected to the heat transferred from the rim.

[0036] Furthermore, since the tire bead and the fob are subjected to the heat transferred from the rim when the vehicle is running, the embodiment of the present application can effectively slow down the transfer of heat by providing a composite heat-insulating coating (3) between the top surface of the rim (1) and the tire bead, and between the top surface of the rim (1) and the fob, thereby reducing the temperature of the tire and the fob, slowing down the aging process of the tire and the fob, and thus extending the service life of the tire.

[0037] The composite heat-insulating coating (3) comprises: an adhesive layer (4) sprayed on the top surface of the wheel rim and a heat-insulating layer (5) sprayed on the adhesive layer.

[0038] In the embodiment of the present application, a composite heat-insulating coating (3) is provided between the top surface of the rim (1) and the tire bead, and between the top surface of the rim (1) and the cushioning strip, wherein the composite heat-insulating coating (3) comprises: an adhesive layer (4) sprayed on the top surface of the rim, and a heat-insulating layer (5) sprayed on the adhesive layer. The adhesive layer (4) is used to improve the mechanical bonding strength between the rim (1) and the heat-insulating layer, and ensure that the heat-insulating layer (5) can be firmly attached to the rim (1). The heat-insulating layer (5) is used to effectively prevent the braking heat from being transferred to the tire through the rim (1), significantly reducing the temperature of the tire, thereby slowing down the phenomenon of accelerated aging of the tire due to high temperature.

[0039] In the embodiment of the present application, an adhesive layer (4) is sprayed on the surface of the rim (1), thereby improving the mechanical bonding strength between the rim (1) substrate and the heat insulation layer (5). Under the premise of ensuring the mechanical bonding strength, the heat insulation performance is improved while the anti-oxidation ability of the rim (1) substrate is improved by setting a suitable porosity. The heat insulation layer (5) is made of ZrO ceramic material, which has excellent heat insulation performance and can effectively prevent the brake heat from being transferred to the tire through the rim (1), thereby slowing down the aging of the tire. The rim (1) of the present application can effectively prevent the brake heat from being transferred to the tire through the rim (1) by spraying the composite heat insulation coating (3), thereby avoiding the risk of tire blowout caused by tire overheating and aging, and improving the service life of the tire. In addition, the embodiment of the present application no longer needs to use a spray device to cool the tire, thereby avoiding serious pollution to the road environment and driving safety issues in cold winter conditions.

[0040] See also Figure 1 In the embodiment of the present application, the bonding layer (4) is made of NiCrAlY material, and the composition ratio of the NiCrAlY material is nickel Ni: 66%, chromium Cr: 25%, aluminum Al: 8%, and yttrium Y: 1%.

[0041] In the embodiment of the present application, the bonding layer (4) in the composite thermal insulation coating (3) is made of NiCrAlY material, wherein the composition ratio of the NiCrAlY material is nickel Ni: 66%, chromium Cr: 25%, aluminum Al: 8%, and yttrium Y: 1%. Nickel Ni is the main element in NiCrAlY, which provides good high-temperature strength and toughness, so that NiCrAlY can still maintain good mechanical properties under high temperature environment. Chromium Cr can enhance the oxidation resistance and corrosion resistance of the alloy. At high temperature, chromium Cr can form a dense chromium oxide layer, which effectively prevents oxygen from further invading the interior of the tire, thereby extending the service life of the tire. Aluminum Al can form an aluminum oxide layer, which can further improve the oxidation resistance of the tire. Yttrium Y is a trace additive element in NiCrAlY alloy, and its main function is to improve the microstructure of the alloy, thereby improving the mechanical properties and oxidation resistance of the alloy. NiCrAlY, as a bonding layer material, not only improves the mechanical bonding strength between the rim (1) and the heat insulation layer (5), but also protects the rim (1) from high-temperature oxidation corrosion through its good anti-oxidation performance.

[0042] See also Figure 1 In the embodiment of the present application, the thickness of the adhesive layer (4) is 100 micrometers to 300 micrometers.

[0043] In the embodiment of the present application, the thickness of the bonding layer (4) in the composite heat-insulating coating (3) is 100 micrometers to 300 micrometers. The thickness of the bonding layer (4) within this range ensures that it can provide sufficient mechanical bonding strength on the wheel and achieve the expected heat-insulating effect. If the thickness of the bonding layer (4) is too thin, it cannot fully support the heat-insulating layer (5) or the wear during use, while if the thickness of the bonding layer (4) is too thick, it will increase unnecessary weight and material cost.

[0044] See also Figure 1 In the embodiment of the present application, the porosity of the bonding layer (4) is 5% to 15%.

[0045] In the embodiment of the present application, the porosity refers to the proportion of the pore volume in the bonding layer (4). Since the thermal conductivity of air is much lower than that of solid materials, an appropriate amount of pores can reduce the conduction of heat, thereby improving the thermal insulation performance. Therefore, the porosity of the bonding layer (4) is set to 5% to 15%, and the overall thermal insulation efficiency of the composite thermal insulation coating (3) is further improved under the premise of ensuring good mechanical bonding strength between the bonding layer (4) and the thermal insulation layer (5).

[0046] Furthermore, since the pores can reduce the direct contact area between the rim (1) and oxygen, thereby slowing down the oxidation process, the porosity of the bonding layer (4) is designed to be 5% to 15%, thereby improving the anti-oxidation ability of the rim (1).

[0047] See also Figure 1 In the embodiment of the present application, the thickness of the thermal insulation layer (5) is 200 microns to 500 microns.

[0048] In the embodiment of the present application, the thickness of the heat insulating layer (5) in the composite heat insulating coating (3) is set to 200 microns to 500 microns, which ensures that the heat can be effectively isolated while also ensuring the economy of the material and the feasibility of processing. An overly thick heat insulating layer (5) will increase the weight and cost of the wheel, while an overly thin heat insulating layer (5) will not achieve the expected heat insulating effect. Therefore, the thickness of the heat insulating layer (5) is selected to be 200 microns to 500 microns, which can effectively isolate the heat generated during the vehicle braking process and reduce unnecessary weight and material costs.

[0049] See also Figure 1 In the embodiment of the present application, the thermal insulation layer (5) is made of ZrO ceramic material.

[0050] In the embodiment of the present application, since the thermal conductivity of the ZrO ceramic material is much lower than that of the metal material and it has excellent heat insulation performance, it can effectively prevent the transfer of heat during vehicle braking. In the composite heat insulation coating (3) of the wheel, the ZrO ceramic material is used as the heat insulation layer (5), which can significantly reduce the transfer of braking heat from the rim (1) to the tire, thereby slowing down the accelerated aging process of the tire due to high temperature and improving the service life of the tire.

[0051] See also Figure 1 In the embodiment of the present application, the spraying method of the composite thermal insulation coating (3) is plasma spraying.

[0052] In the embodiment of the present application, the composite heat-insulating coating (3) is sprayed by plasma spraying. Specifically, the bonding layer (4) is first sprayed on the surface of the rim (1) by plasma spraying. The bonding layer (4) can improve the mechanical bonding strength between the rim (1) substrate and the heat-insulating layer (5). At the same time, the bonding layer (4) has a certain porosity. Under the premise of ensuring the mechanical bonding strength, setting a suitable porosity can also improve the heat-insulating performance. The heat-insulating layer (5) is sprayed on the bonding layer (4) by plasma spraying. The heat-insulating layer (5) is a ZrO ceramic material with excellent heat-insulating performance, which can effectively prevent the braking heat from being transferred to the tire through the rim (1), thereby slowing down the aging of the tire.

[0053] See also Figure 1In the embodiment of the present application, the thermal conductivity of the composite thermal insulation coating (3) is 0.539 W / (m·K).

[0054] In the embodiment of the present application, thermal conductivity is a thermal property parameter of a material, which indicates the amount of heat that passes through a unit area per unit time for a material of unit thickness at a unit temperature difference. The thermal conductivity of the composite thermal insulation coating (3) is 0.539 W / (m·K), which means that for each meter of the composite thermal insulation layer (3), when the temperature difference is 1 Kelvin, the amount of heat that passes through a unit area per second is 0.539 watts. Therefore, the thermal conductivity of the composite thermal insulation coating (3) is relatively small, and it has good thermal insulation performance.

[0055] See also Figure 1 In the embodiment of the present application, the rim (1) and the spokes (2) are both made of steel.

[0056] In the embodiment of the present application, when a vehicle is carrying heavy cargo and traveling on a road with complex road conditions, such as vehicles in mining areas and slag transport vehicles, such vehicles need to withstand heavy loads and frequent braking, so the wheel rim (1) and spokes (2) are made of steel. Steel has high strength and good durability, and can therefore withstand the load pressure and frequent braking pressure of the vehicle.

[0057] Figure 2 A temperature comparison diagram of whether the wheel unit provided in the embodiment of the present application contains a composite heat-insulating coating. The wheel unit of the present application and the common wheel of the prior art are installed on the same vehicle. The vehicle is loaded with goods and driven on a long downhill slope, and then the vehicle is driven by frequent braking. The temperature of the wheel unit rim (1) of the present application is measured and recorded, and the temperature of the common wheel rim of the prior art is measured and recorded. The temperature comparison result is shown in the figure below. Figure 2 As shown, the straight line represents the temperature of the wheel unit rim (1) of the present invention, and the dotted line represents the rim temperature of the conventional wheel in the prior art. It is obvious that the temperature of the wheel unit rim (1) of the present invention is lower than the rim temperature of the conventional wheel in the prior art from beginning to end. Moreover, at the highest temperature, the temperature of the wheel unit rim (1) of the present invention is reduced by 40 to 50 degrees Celsius compared to the rim temperature of the conventional wheel in the prior art. Therefore, the wheel unit of the present invention can effectively prevent the high braking temperature from being transmitted to the tire through the rim.

[0058] In summary, the wheel unit provided in the embodiment of the present application reduces the heat transferred from the rim (1) to the tire during braking by setting a suitable porosity for the bonding layer (4), spraying the bonding layer (4) onto the top surface of the rim (1) by plasma spraying, and then spraying a heat insulating layer (5) made of ZrO ceramic material on the bonding layer (4). Therefore, the present application protects the tire from high temperature damage and extends the service life of the tire. In addition, when using the wheel unit of the present application, there is no need to install an additional spray device to cool the tire, thereby avoiding serious pollution to the road environment and avoiding the problem of ice on the road surface caused by the spray device in the cold winter, which in turn causes the road surface to be slippery and seriously affects driving safety.

[0059] Based on the same technical concept, the embodiment of the present application further provides a vehicle, including the above wheel unit provided by the embodiment of the present application. The vehicle provided by the embodiment of the present application can be applied to all application scenarios using the above wheel unit.

[0060] The serial numbers of the embodiments of the present application are only for description and do not represent the advantages and disadvantages of the embodiments. The above are only preferred embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A wheel unit, characterized in that: include: A rim (1) and a spoke (2), wherein the rim (1) and the spoke (2) are connected by welding, the top surface of the rim (1) is in contact with a tire bead and a cushioning strip respectively, and a composite heat-insulating coating (3) is provided between the top surface of the rim (1) and the tire bead, and between the top surface of the rim (1) and the cushioning strip; The composite heat-insulating coating (3) comprises: an adhesive layer (4) sprayed on the top surface of the rim (1) and a heat-insulating layer (5) sprayed on the adhesive layer.

2. The wheel unit according to claim 1, characterized in that The bonding layer (4) is made of NiCrAlY material, and the composition ratio of the NiCrAlY material is nickel Ni: 66%, chromium Cr: 25%, aluminum Al: 8%, and yttrium Y: 1%.

3. The wheel unit according to claim 2, characterized in that: The thickness of the bonding layer (4) is 100 micrometers to 300 micrometers.

4. The wheel unit according to claim 1, characterized in that: The porosity of the bonding layer (4) is 5% to 15%.

5. The wheel unit according to any one of claims 1 to 4, characterized in that: The thickness of the heat insulation layer (5) is 200 micrometers to 500 micrometers.

6. The wheel unit according to any one of claims 1 to 4, characterized in that: The heat insulation layer (5) is made of ZrO ceramic material.

7. The wheel unit according to claim 1, characterized in that: The composite heat-insulating coating (3) is sprayed by plasma spraying.

8. The wheel unit according to claim 1, characterized in that: The thermal conductivity of the composite heat-insulating coating (3) is 0.539 W / (m·K).

9. The wheel unit according to claim 1, characterized in that: The rim (1) and the spokes (2) are both made of steel.

10. A vehicle, characterized in that: A wheel unit comprising any one of claims 1 to 9.

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