Patent Application
20220136575
The present disclosure generally relates to wheels, systems, and methods for braking and, more particularly, to automotive alloy wheels with an integral braking surface and methods for providing deceleration, reducing weight, and enhancing energy efficiency.
Wheels made from aluminum, magnesium, or titanium alloys are becoming standard features for many automobiles. Generally termed as “alloy wheels,” they are significantly lighter than steel ones, and benefit vehicles in terms of fuel economy, braking, and accelerating. Steering and handling is also often improved with lighter wheels. The alloy wheels also help limit wear and tear on other vehicle components such as the engine, transmission, suspension, and the like. Alloy wheels also permit better heat conduction and dissipation, which directly translates to better braking. Enhanced heat dissipation also keeps tires cooler and reduces wear. Further, alloy wheels are more resistant to corrosion and rust, and aesthetically look far more stylish compared to steel wheels.
While aluminum, magnesium, or titanium alloy wheels provide many benefits, for braking, heavier steel or cast iron disc or drum rotors are generally used, which are separately manufactured and fastened to a hub. Besides significant weight addition to the vehicle, galvanic incompatibility between iron and aluminum/magnesium/titanium alloys often necessitates isolation between the wheel and the brake rotor. Further, the steel/cast iron rotors are prone to corrosion and rust, which affect the braking performance and dust generation, as well as impact the aesthetics of the vehicle. Furthermore, hybrid and electric vehicles are prone to enhanced corrosion and rust due to reduced use of mechanical brakes.
If the same light alloys that are used to make the wheels can be utilized to make the brake rotor, then the vehicle weight can be further reduced, leading to higher energy efficiency as well as better braking performance. Furthermore, the brake rotor/braking surface can then be integrated into the alloy wheel as a single component to improve heat dissipation and simplify manufacturing and assembly.
Accordingly, a need exists for improved automotive alloy wheels that provide deceleration, reduce weight, and enhance energy efficiency.
In one embodiment, a braking assembly for inhibiting rotation of a wheel around a rotation axis includes a drive gear, an actuator, an electric braking assembly, a mechanical braking assembly, and a brake rotor. The drive gear is configured to rotate with the wheel and includes a pinion. The electric braking assembly includes a coil surrounding the rotation axis, and a magnetic disc assembly concentric with the coil and configured to rotate relative to the coil. The magnetic disc assembly includes a plurality of magnets at a perimeter of the disc. The mechanical braking assembly includes a brake pad. The brake rotor is fixedly coupled to the wheel. The actuator engages the pinion to mechanically couple the drive gear and the magnetic disc assembly to cause relative rotation between the plurality of magnets and the coil to generate an electro motive force that inhibits rotation of the wheel around the rotation axis. The actuator also engages the brake pad such that the brake pad contacts the brake rotor causing friction that inhibits relative rotation between the wheel and the brake pad.
In another embodiment, a wheel assembly includes a wheel and an integrated brake rotor. The wheel includes a hub, a rim, and one or more spokes extending between the hub and the rim. The integrated brake rotor includes a braking surface, a plurality of fins, and an alloy.
In yet another embodiment, a wheel and brake assembly for inhibiting rotation of a wheel around a rotation axis includes a wheel, a mechanical braking assembly, and a brake rotor fixedly coupled to the wheel. The wheel includes a hub, a rim, and one or more spokes extending between the hub and the rim. The mechanical braking assembly includes an actuator and a brake pad. The actuator engages the brake pad such that the brake pad contacts the brake rotor causing friction that inhibits relative rotation between the wheel and the brake pad. The brake rotor and the wheel are each formed from one or more alloys.
In yet another embodiment, a motor/generator assembly for rotating and inhibiting rotation of a wheel on a vehicle includes a rotating bearing, a rotor coil mounted to an axle such that it rotates with the axle as the wheel rotates, a stator including one or more magnets, the stator coupled to the rotor coil via the rotating bearing and concentric with the rotor coil about the axle, and an actuation assembly including an actuation arm, the actuation assembly configured to actuate the actuation arm to contact the stator. Contact of the actuation arm with the stator inhibits rotation of the stator with respect to the vehicle, thereby causing relative rotation between the rotor coil and the stator.
These and additional features provided by the embodiments described herein will be more fully understood in view of the following detailed description, in conjunction with the drawings.
The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, wherein like structure is indicated with like reference numerals and in which:
Referring now to
In embodiments described herein, the brake rotor 102 is an integrated brake rotor. As used herein, the term “integrated” or “integral” refers to two components being integrally formed as a one piece, monolithic structure formed of the same material. The integrated brake rotor 102 may be monolithic with one or more of the hub 108, the rim 110, and the one or more spokes 112. In some embodiments, the brake rotor 102 is an alloy such as, for example, an alloy of one or more metals such as aluminum, copper, tin, magnesium, and other materials. In some embodiments, the brake rotor 102 is a reinforced composite, such as, for example, an alloy matrix of one or more metals such as aluminum, copper, tin, magnesium with fiber or particle reinforcement such as C, SiC, or Al2O3. In some embodiments, the alloy is a composite material. In some embodiments, the alloy is a SiC (silicon carbide) reinforced aluminum alloy composite. The brake rotor 102 and the other wheel assembly components may be produced using one or more methods, for example, forging, casting (e.g., high pressure die casting, low pressure die or sand casting, gravity casting, and the like), extrusion, MIG welding, and powder coating. In some embodiments, the brake rotor is machined into shape from a 6061 aluminum block and the wheel 101 is cast from an A356 aluminum alloy by sand casting. The wheel assembly 100 is then formed by MIG welding of the brake rotor 102 and the wheel 101. As shown in
The fins 106 may extend away from the braking surface 104 to remove heat from the braking surface 104 as the brake is actuated and friction is created. In addition, the fins 106 also provide mechanical support to the braking surface 104 (e.g., increase the stiffness). In some embodiments, as described herein, the brake rotor 102 may include multiple braking surfaces and the fins 106 may be situated between the multiple braking surfaces. In the particular illustrated embodiment in
Referring now to
As shown in the inset in
In some embodiments, the liner 116 may be an alloy layer on a metal (including metal alloys). The liner 116 may contact and overly at least a portion of the substrate, i.e., the base or brake rotor 102. The liner 116 may comprise a mechanically tough alloy having dissolved nitrogen and may having a substantially homogeneous composition. In embodiments, the composition of the liner 116 may be, by weight percent, 0.1 wt % to 2 wt % nitrogen (N). Further, the liner 116 may include a single phase nitrogen alloy. The wheel assembly 100 or components thereof may include a metal substrate having a substrate composition and a substrate interface. The substrate interface may include thereon a protective nitrogen containing alloy layer. It is contemplated that the alloy or overlying layer may be an iron containing alloy.
In some embodiments, the wheel assembly 100 and the liner 116 may be prepared using solid precursor materials having the desired dissolved nitrogen deposed to form the protective alloy layer on the substrate surface. Methods of forming may include exposing a liquid alloy having alloying elements that promote dissolution of nitrogen to a high partial pressure nitrogen atmosphere to induce high dissolved nitrogen, and then solidifying the alloy in a manner such that the dissolved nitrogen in the liquid alloy is substantially captured in the solid precursor material. In some embodiments, the methods further include avoiding any intermediate phase formation that has low nitrogen solubility and/or rapid solidification to prevent nitrogen loss. The form of the precursor solid may be micron sized powders. In some embodiments, the form of the precursor solid is a thin strip having a thickness of from 0.1 millimeters (mm) to 5 mm.
In embodiments, the wheel assembly 100 may be a composite article. An overlying layer of nitrogen containing alloy may be overlaid onto a substrate by processes wherein the nitrogen containing alloy precursor material is kept substantially solid during fabrication, thus preventing dissolved nitrogen loss. The methods may include providing a cold spray deposition process to deposit micron sized powder precursor having dissolved nitrogen, thereby forming the overlying layer. In some aspects, the methods include a joining process forming the overlying layer, wherein both a thin strip of precursor material and the substrate are kept substantially in solid state. In yet other aspects, the methods include a casting process, wherein a thin strip precursor is kept substantially in solid state and contacting a substantially liquid metal/alloy. Upon cooling, the liquid metal solidifies forming the substrate while the thin strip precursor forms the overlying layer.
“Precursor” as used herein means the material deployed to fabricate the nitrogen containing liner 116 (e.g., a protective layer) on a substrate, such as the brake rotor 102. In specific aspects, the precursor is the solid powder or the thin strip intended for making the layer. “Composite” as used herein means an article made up of several parts or elements. Specifically, the composite is an object having a substrate and the liner 116 intended to provide functionalities that are not otherwise provided by the individual elements alone. “Compound” as used herein, means a material formed by reactions between elements having a stoichiometric ratio, for example, Cr2N, F2N, TiN, and the like.
The addition of nitrogen may improve the strength, ductility, and impact toughness in austenitic steels, while the fracture strain and fracture toughness are not affected at elevated temperatures. The strength of nitrogen alloyed austenitic steels arises from three components: strength of the matrix, grain boundary hardening, and solid solution hardening. The matrix strength is not appreciably impacted by nitrogen, rather, the matrix strength correlates to the friction stress of the FCC (face centered cubic) lattice that is mainly controlled by the solid solution hardening of the substitutional elements like chromium and manganese. Grain boundary hardening, which occurs due to dislocation blocking at the grain boundaries, increases proportionally to the alloyed nitrogen content. The highest impact on the strength results from the interstitial solid solution of nitrogen. Nitrogen increases the concentration of free electrons promoting the covalent component of the interatomic bonding and the formation of Cr—N short range order (SRO). The occurrence of Cr—N SRO and the resultant interactions with dislocations and stacking faults are believed to play a major role in the deformation behavior of these alloys and can be tailored to enhance the strength, ductility, and impact toughness.
The composition and temperature strongly influence the stacking fault energy (SFE) and, in turn, the deformation mechanisms and strengthening behavior of austenitic steels. Increasing the SFE causes the active deformation mechanisms to change and is generally favored to achieve pure dislocation glide and enhanced toughness. Specifically, the effect of N additions on the SFE in Cr and Mn alloyed steels are reported to be non-monotonic, exhibiting a minimum SFE at about 0.4 wt % nitrogen. The decrease in SFE at low nitrogen contents is believed due to the segregation of interstitial nitrogen atoms to stacking faults. However, at higher nitrogen contents, the SFE increases as the bulk effect of interstitial solid solution becomes more pronounced. The formation of nitrides, such as Cr2N, TiN, AlN, and the like, at elevated nitrogen content affects the distribution of alloying elements within the lattice and, in turn, diminishes the bulk effect of interstitial solid solution and the SFE. The formation of nitrides such as Cr2N occurs when the nitrogen content goes beyond certain threshold value (depends on the overall composition of the alloy) and should be discouraged to take advantage of the interstitial solid solution hardening phenomenon described above.
High nitrogen containing austenitic steels also exhibit excellent resistance to atmospheric corrosion. However, the corrosion resistance is also strongly influenced by the nitrogen content. At low nitrogen contents, the formation of σ phase (an intermetallic compound with Cr) at the grain boundaries as well as the formation of nitrides such as Cr2N at high nitrogen content are detrimental to the corrosion resistance of these steels. Optimal corrosion resistance can be achieved if all nitrogen is in solid solution, i.e., no nitrides are precipitated.
An optimal combination of toughness and corrosion resistance can be achieved by limiting the nitrogen content within a range, wherein a substantially or completely precipitation free homogeneous microstructure with nitrogen in solid solution form can be obtained. This range of dissolved nitrogen depends on other alloying elements present in the alloy as well as the process thermal history, which is discussed in more detail herein. Reductions in toughness and corrosion resistance may occur rapidly as the nitrogen content either decreases or increases from a desired range. As will be appreciated, the widely used industrial techniques such as nitriding or nitride PVD coatings cannot provide the liner 116 with homogenous nitrogen content on a substrate, wherein the nitrogen is in the desirable solid solution state. During nitriding, the nitrogen content will vary considerably at the surface forming compounds having high nitrogen to a very low level toward the core. In the case of nitride sputter coating, a coating may be made of brittle compounds even though the composition may mostly stay relatively uniform across a layer.
One approach to obtain a homogeneous dissolved nitrogen content in a metallic alloy, specifically in austenitic steel is to: (i) dissolve the nitrogen into the alloy in liquid state; and (ii) subsequently solidify the alloy without losing the dissolved nitrogen during solidification. However, both the tasks have their own challenges. For example, the nitrogen solubility in liquid iron at atmospheric pressure is very low (0.045 wt % at 1,600° C.). Nitrogen in liquid alloy increases by the square root of the partial pressure (Sievert's square root law). Hence, to introduce higher nitrogen into liquid iron/steel, melting should be done using a high pressure nitrogen environment. Nitrogen alloying in the molten state may be achieved by high pressure induction or electric arc furnaces, pressure electro slag remelting furnace (PERS), and plasma arc and high-pressure melting with hot isostatic processing (HIP) or the like.
The addition of certain elements such as chromium, manganese vanadium, niobium, and titanium increases the nitrogen solubility, while the addition of elements such as carbon, silicon, and nickel reduces the nitrogen solubility. Hence, in order to induce high nitrogen concentrations into the melt, chromium and manganese can be added and nickel should be avoided. Furthermore, in some aspects, elements such as vanadium, niobium, and titanium are absent or present in insignificant amounts as they are powerful nitride formers.
The production of high nitrogen containing austenitic steels by prior methods requires a balanced control of the alloy composition and precise adjustment of the melting and solidification conditions. Toughness and corrosion resistance of such alloys can also be exploited to provide protective layers on articles as an effective solution to the problems associated with traditional nitriding and nitride coatings.
The wheel assembly 100 may comprise the liner 116 and a base. It should be understood that reference to the base may refer to the brake rotor 102 and, specifically, the braking surface 104 of the brake rotor 102. When the brake rotor 102 is integrated with the wheel 101, the base may refer to composition of both the brake rotor 102 and the wheel 101. The base and the liner 116 may have a metallurgical bond at an interface of the base and the liner 116. The dissolved nitrogen content within the liner 116 may be uniform and may be higher than the solubility limit of nitrogen in the base in its liquid state at atmospheric pressure. The liner 116 may be devoid of a nitride compound or nitride compound layer such as that which occurs in nitriding or nitride coating processes. Although, the desired dissolved nitrogen content will vary from one application to another, the nitrogen content may be adjusted such that undesirable precipitation formation is avoided to improve mechanical toughness and corrosion resistance. The nitrogen content in the liner 116 may be between 0.1 wt % and 2.0 wt %. In some embodiments, the nitrogen content in the liner 116 is between 0.4 wt % and 0.9 wt %.
The base may be a surface that is flat, substantially flat, curvilinear, or any other desired shape with concave, convex, or other surface configuration as described herein. The base may be or include a metal alloy. Illustrative examples of metal alloys include, but are not limited to, alloys that include Al, Si, B, Cr, Co, Cu, Ga, Au, In, Fe, Pb, Mg, Ni, C, a rare earth (e.g. La, Y, Sc, or the like), Na, Ti, Mo, Sr, V, W, Sn, Ur, Zn, Zr, or any combination thereof. In some aspects, the base includes Al or an alloy of Al. In some embodiments, the base includes Al from 80 wt % to 100 wt %. In some embodiments, the base includes a cast iron or a steel. In some embodiments, the base includes a Ti alloy. In some embodiments, the base includes a reinforced composite, including one of the above metal alloy matrix and fiber/particulate reinforcement. Illustrative examples of reinforcement phase include SiC, Al2O3, or C. In some embodiments, the volume fraction of the reinforcement phase is between 5% and 75%. In some embodiments, the volume fraction of the reinforcement phase is between 20% and 35%. In some embodiments, the volume fraction of the reinforcement phase is between 40% and 55%.
The liner 116 includes a metal or metal alloy with dissolved nitrogen at a desired concentration so as to provide desired functionality in terms of toughness and corrosion resistance. The liner 116 may be an austenite metal alloy and, in some embodiments, includes Fe as a predominant metal in the alloy. The metal alloy may include N and Fe, referred to herein as an FeN layer, whereby the N is present at a sufficient amount so as to promote an austenite structure. In some embodiments, N present at a weight percent from 0.05 wt % to 2 wt % or any value or range therebetween. In some embodiments, N is present at a weight percent from 0.1 wt % to 1.5 wt %, in some embodiments from 0.2 wt % to 2 wt %, in some embodiments from 0.2 wt % to 1.9 wt %, in some embodiments from 0.3 wt % to 1.9 wt %, in some embodiments from 0.3 wt % to 1.8 wt %, in some embodiments from 0.4 wt % to 2 wt %, in some embodiments from 0.4 wt % to 1.9 wt %, in some embodiments from 0.4 wt % to 1.8 wt %, or in some embodiments from 0.4 wt % to 1.5 wt %. The amount of N may be dependent on the desired fraction of austenite in the final material and the final composition of the material.
As discussed herein, in embodiments including the liner 116, the liner 116 may include Fe, which may be present at a predominant amount at a weight percent of 51 wt % or greater, in some embodiments at a weight percent of 52 wt % or greater, and in some embodiments at a weight percent of 55 wt % or greater. With Fe as a predominant metal, an alloy may be a solid solution with FCC structure, at the temperature at which the material is expected to be used, in some embodiments from −150° C.±5% to 1,000° C.±5%. The amount of N and other elements is designed to promote the FCC structure of the metal alloy such that this structure is promoted and maintained at temperatures up to 1,000° C.±5%. As such, the metal alloy in some embodiments is substantially 100% FCC structure and in some embodiments 99% FCC structure. In some embodiments, a metal alloy of the liner 116 is 95% FCC structure or greater. In some embodiments, a metal alloy of the liner 116 is 50% FCC structure or greater. In some embodiments, the liner 116 alloy is free of other structures such as FCC. It is to be appreciated that the wheel 101 and the brake rotor 102 themselves may also include a similar composition to that of the liner 116 described herein. Thus, the wheel 101 and the brake rotor 102 may also comprise a FeN alloy.
In addition to nitrogen, the liner 116 may include one or more other elements that will promote FCC structure. For example, the liner 116 may include Mn. When present, Mn may be provided at a weight percent from 0 wt % to 35 wt %. In some embodiments, the weight percent of Mn is less than 30 wt %. In some embodiments, the weight percent of Mn is from 19 wt % to 27 wt %. In some embodiments, the weight percent of Mn is from 20 wt % to 26 wt %. The presence of N in such alloys serves to promote and stabilize a desired FCC structure even when the amount of Mn or other FCC promoting metal is less than 20 wt %. As such, the dissolved N and Mn work in concert to promote austenitic structure to the protective layer metal alloy. The liner 116 may include Ni, which also promotes austenitic structure. When present, Ni may be provided at a weight percent from 0 wt % to 20 wt %. Since Ni reduces the N solubility in the liner 116, the Ni may be from 0 wt % to 5 wt %. The liner 116 may include C. When present, C may be provided at a weight percent from 0 wt % to 0.2 wt %. While C improves N solubility, it also reduces the toughness of the resulting alloy. The C may be present in the alloy from 0 wt % to 0.1 wt %.
Cr may be included in the provided N alloy. In order to control the phase of the liner 116, the ferrite stabilizing effect of Cr may be countered by adjusting the amount of N and/or Mn, both of which serve as austenite stabilizers. Further, the substrate material properties may also be taken into consideration in designing the provided alloy. For example, if the substrate is an aluminum alloy which has a FCC structure, the liner 116 alloy may be 100% austenite (FCC) phase in order to match the thermal coefficient of expansion of the base and other components of the wheel assembly 100. When the base is a ferritic cast iron or steel, a mixture of austenite and ferrite structure may be chosen. In some embodiments, a protective layer is 100% austenite, in some embodiments 90% austenite or greater, in some embodiments 80% austenite or greater, in some embodiments 70% austenite or greater, in some embodiments 60% austenite or greater, and in some embodiments 50% austenite or greater.
The liner 116 may include one or more other metals. The liner 116 may include molybdenum (Mo). When present, Mo may be provided at a weight percent of 0 wt % to 5 wt %. A protective layer metal alloy may include aluminum (Al). When present, Al may be provided from 0.01 wt % to 10 wt %. In some embodiments, Al is present at or less than 10 wt %, in some embodiments at or less than 8 wt %, and in some embodiments at or less than 6 wt %.
Still referring to
Disposing the alloy precursor on the components of the wheel assembly 100 may be achieved either manually by placing the substrate in a desired manner or via an automated system that disposes the substrate in accordance to a predetermined program. The latter approach may be used, for example, in industrial implementation. The surface quality of the precursor N alloy may be considered as a factor in the joining process. Two types of bonding can occur between the substrate and the protective layer. In the case of nitriding, wherein the protective layer grows on the substrate through diffusion process, resulting bonding may be referred to as metallurgical bonding. Similarly, fusion joining as is achieved in this disclosure may also establish a metallurgical bond. On the other hand, deposition processes such as plasma spraying establish a mechanical adhesion, wherein extensive surface preparation such as grit blasting or surface grooving is necessary for good adhesion.
Additionally, a strip precursor may be disposed onto one or more surfaces of the wheel assembly 100 (e.g., at the interface between the liner 116 and the wheel assembly 100). The strip precursor may be joined to the substrate and may remain substantially solid during the joining process, ensuring the retention of the dissolved nitrogen in the liner 116. The joining process may be a linear friction welding process, wherein the interfacial layer may soften into a plastic state due to oscillating linear motion between the precursor and the substrate and upon cooling may form a metallurgically bonded joint. In some embodiments, the strip precursor comprises preformed anchors and is deposed onto a molten alloy, the latter upon solidification forms the substrate. The embedment of the anchors into the solid substrate ensures the adhesion to the substrate. The molten alloy temperature may be below the melting point of the precursor alloy so that the precursor does not appreciably melt and lose its dissolved nitrogen, although surface interaction may promote metallurgical bonding.
In some embodiments, a solid powder precursor may be deposed onto the substrate at high velocity which may form a metallurgical bonding with the wheel assembly 100 upon impact to form the liner 116. This can be suitably achieved by a supersonic nozzle, wherein the solid powder precursor is injected into a high velocity gas jet which accelerates the powders. The gas may be heated to increase the powder temperature, but to keep it below the melting point. Additional energy may be provided onto the powder or both the substrate and the powder. However, the precursor and the layer remain below the melting point throughout the forming process.
In embodiments, the energy source may be a laser, an electron beam, a plasma, or an infrared source. The deposition nozzle may move forward according to CAD data or tool path generated by a control system to build the nitrogen alloy protective layer over the substrate. The nozzle movement can be done manually.
In some embodiments, a logic gate may determine the need for additional thickness of the liner 116 (e.g., more layers). If an additional layer is required, one or more of the previously listed steps may be repeated. When the powder precursor is used, only thin layers (˜micrometers) may be built in one pass and hence the process is repeated multiple times to build an appreciable thickness of the protective alloy layer. If the desired layer thickness has been fabricated, the composite object may be cooled to ambient temperature. It is to be understood that the steps described herein are not necessarily discrete and that there may be overlap between some steps leading to a continuous fabrication process. Additionally, one or more of the above steps or components thereof may be omitted.
In yet other embodiments, a strip precursor may be disposed onto the wheel assembly 100 and may be subject to a mechanical load and oscillating movement with an amplitude sufficient to generate friction and heat along the interface. The substrate may be held stationary and the strip precursor may make the oscillating movement to generate friction. The mechanical friction and heat along the interface may generate a thin plastic zone at the interface. Much of this plasticized material may be removed from the weld, as flash, because of the combined action of the applied force and part movement. Surface-oxides and other impurities may be removed, along with the plasticized material, which may allow metal-to-metal contact between parts and enable a metallurgic joint to form. The process may be referred to as friction welding. The motion between the substrate and the strip precursor can be rotary depending upon the geometry. Such an effect may take place in the solid state and involve no melting of the parts to be joined, ensuring the retention of the dissolved nitrogen in the protective alloy layer. The strip precursor thickness may be between 0.5 mm and 10 mm, and may be between 0.5 mm and 2 mm. Further, the strip precursor may be cut into a size that can either cover a portion of a surface of the wheel assembly 100 or entirely cover a surface of the wheel assembly 100. To obtain a strong joint, a specific power input should be exceeded. The frequency, amplitude, and pressure have an effect on this parameter, which was defined as:
with α being the amplitude; f the frequency; P the pressure; and A the interface area. From this relationship, it can be seen that the power input can be increased by increasing the frequency, amplitude, or pressure. For example, to join the nitrogen alloy strip precursor with 40×25 mm area onto an aluminum substrate, the parameters may be: frequency 30 Hz to 60 Hz; amplitude±2 mm to ±3 mm; pressure 80 MPa to 150 MPa; and time 7 seconds to 25 seconds.
For a large article, the mechanical force required to make a friction weld across a large area may be difficult to control. Additional manufacturing methods may include use of a solid nitrogen alloy precursor having anchors deposed adjacent to a liquid or semi-solid metal/alloy substrate such that the anchors are immersed in the fluid. The melting point of the fluid metal/alloy point may be lower than that of the nitrogen alloy layer such that the precursor solid does not melt. Upon solidification, the fluid may form the substrate and the precursor may become the protective layer. As one example, the solid precursor may be a nitrogen alloy steel and the substrate may be an aluminum alloy. Both wear and corrosion resistance of an aluminum article may be enhanced using such a process. The contact time between the solid precursor and the substrate fluid may be minimized to prevent any detrimental reaction and intermetallic formation between the precursor and the substrate alloy. The fluid substrate metal may be supplied from a bottom of a casting assembly so that it comes into contact with the solid precursor at an end of the casting assembly, and upon contact immediately solidifies minimizing the interfacial reaction. The fluid metal may be supplied by an electromagnetic pump from the bottom of a casting assembly having the precursor solid disposed at a top of a mold cavity. The substrate alloy may be a semi-solid that behaves like a fluid due to heavy shear action during the feeding process. Thus, the overall temperature of the fluid may be at a few hundred degrees C. below the melting point, but can be filled into the cavity easily. This may further limit the surface interaction between the precursor and the substrate fluid. Such a casting process may be referred to as thixocasting.
In embodiments, manufacturing the liner 116, i.e., coating, on the wheel assembly 100 may include use of a cold spray nozzle operably connected to a gas heater and a powder feeder. A gas inlet may supply gas to the gas heater at high pressure. This may be referred to as process gas. Further, gas may also be supplied to the powder feeder. This may generally referred to as carrier gas. The process gas pressure may be the same as the carrier gas pressure, however, they may operate at different pressures. The process gas pressure may be 100 pounds per square inch (PSI)±10%, 200 PSI±10%, 300 PSI±10%, 400 PSI±10%, 500 PSI±10%, 600 PSI±10%, 700 PSI±10%, 800 PSI±10%, or higher. The process gas pressure may be from 100 PSI to 800 PSI, or any value or range therebetween. In some embodiments, the process gas may be 40 scfm±10% (standard cubic feet per minute), 50 scfm±10%, or 60 scfm±10%. The process gas may be heated by a gas heater prior to entering into a convergent and divergent nozzle, wherein the gas attains very high velocity in the divergent section. There are many known variants of the nozzle geometry in the art. In some embodiments, the nozzle speed is 5 mm/s±10%, 10 mm/s±10%, 15 mm/s±10%, and 20 mm/s±10%. The process gas temperature may be 50° C., 100° C., 200° C., 300° C., 400° C., 500° C., 600° C., 700° C., 800° C., 900° C., or higher. The process gas temperature may be from 50° C. to 900° C., or any value or range therebetween. The nitrogen alloy precursor powder may be supplied by the powder feeder and may be carried by the carrier gas and may be delivered to the process gas stream. The precursor powder can be delivered in a convergent section of a nozzle or a divergent section of a nozzle. The powder feeder temperature may be 50° C., 100° C., 200° C., 300° C., 400° C., 500° C., 600° C., 700° C., 800° C., 900° C., or higher. The carrier gas pressure may be 100 PSI±10%, 200 PSI±10%, 300 PSI±10%, 400 PSI±10%, 500 PSI±10%, 600 PSI±10%, 700 PSI±10%, 800 PSI±10%, or higher. The powder feeder rate may be between 3 g/min (grams per minute) and 10 g/min. In some embodiments, the powder feeder rate is between 6 g/min and 8 g/min. The cycle time may be between 1 minute and 5 minutes. In some embodiments, the cycle time may be between 3 minutes and 4 minutes. The carrier gas pressure may be from 100 PSI to 800 PSI, or any value or range therebetween. In some embodiments, the process gas may be between 1 scfm and 5 scfm and, in some embodiments, the process gas may be between 1 scfm and 2 scfm. The precursor solid powder having the dissolved nitrogen absorbs heat from the process gas as well as accelerates towards the substrate due to drag force exerted by the process gas. Unlike conventional plasma spraying, the bonding occurs through a process termed as “adiabatic shear instability” that leads to a metallurgical bonding. The powder particle must attain a required velocity to form a metallurgical bond with substrate, which is known as the critical velocity in the art. The critical velocity depends on the precursor powder properties, size, temperature as well as the properties of the substrate and substrate temperature. The process parameters are adjusted accordingly to provide critical velocity to maximum number of the particles in the particle stream. For example, a nitrogen alloy powder having 0.7 wt % N, 19 wt % Mn, 15 wt % Cr and the rest iron with powder size ranging from 20 μm to 45 μm requires a critical velocity in excess of 500 m/s at 500° C. particle temperature to successfully form a consolidated alloy layer. In some embodiments, the precursor powder size is between 5 microns and 250 microns, in some embodiments between 5 microns and 150 microns, and in some embodiments between 10 microns and 75 microns. The particle stream may be directed onto the substrate and upon impact and bonding, a protective layer is consolidated. The powder temperature as well as the target temperature remains substantially below the melting point of the alloy, thereby retaining the alloyed nitrogen in the protective layer. Thus, the coating layer fabrication can be carried in open atmosphere without requiring a high pressure nitrogen environment. Further, the spray nozzle may be operably connected to a robot that can traverse the nozzle according to a preprogrammed path. Further, the protective layer can be built layer by layer until the required thickness is achieved. Depending upon the application, in some embodiments the thickness of the layer is 5 microns, in some embodiments 10 microns±10%, in some embodiments 100 microns±10%, in some embodiments 1,000 microns±10%, and in some embodiments greater than 1,000 microns. The ancillary componentry such as the power supply, control systems, auxiliary heating source, and gas tanks are not shown and their inclusion in the system is understood. The manufacturing system can be configured in a variety of ways. For example, a CNC motion system can be utilized instead of a robot. Further, another robot can be deployed to manipulate the substrate. The entire system can be enclosed in a controlled environmental chamber.
In some embodiments, a nitrogen alloy layer may be fabricated in various forms. The nitrogen content across the entire layer may be uniform. Some embodiments may include a protective layer that has two different nitrogen contents along the thickness. This can be achieved by utilizing two different powder precursors with different nitrogen content. Additionally, the nitrogen content can be progressively varied along the thickness by deploying several powders with progressively varying nitrogen content.
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The mechanical braking assembly 120a includes a pair of brake shoes 122a, each including a brake pad, such as the brake pad 122, one or more biasing springs 108a, and an actuator 110a. The actuator 110a actuates forcing the brake shoes 122a apart from one another radially such that the contact of the brake shoes 122a on the braking surface 104a of the brake rotor 102a inhibits rotation of the wheel 101a. The brake shoes 122a include an exterior surface 123 that extends at least partially around a circumference of the mechanical braking assembly 120a and is configured to contact the braking surface 104a upon actuation of the mechanical braking assembly 120a to inhibit rotation of the wheel assembly 100a. Upon actuation of the actuator 110a, the brake shoes 122a expand radially outward, thereby contacting the braking surface 104a of the brake rotor 102a. The biasing spring 108a may return the brake shoes 122a to their original position when the actuator 110a is released.
Referring now to
Referring now to
The braking assembly 205 further includes a mechanical braking assembly 222 that includes a brake pad 224, and a brake rotor 202 that is fixedly coupled to the wheel 201. In some embodiments, the brake rotor 202 is an integrated brake rotor, but it is to be understood that the brake rotor 202 may be separate from the other components of the wheel 201 in some embodiments. The mechanical braking assembly 222 may operate similarly and be constructed similarly to the mechanical braking assembly 120 and the mechanical braking assembly 120b, as described herein and in some embodiments may be substituted. Thus, the disclosure above with regard to the mechanical braking assembly 120 is equally applicable to the mechanical braking assembly 222 and, therefore, includes like reference numerals where appropriate. Similarly, it should also be appreciated that the brake rotor 202 may be substituted for either of the brake rotor 102, the brake rotor 102′, the brake rotor 102a, and the brake rotor 102b as like components discussed herein may be applicable between wheel assemblies.
The actuator 208 may actuate to couple the pinion 220 between the drive gear 206 and the disc gear 232. The pinion 220 may include a pinion gear piston 221 that is fluidly coupled with the actuator 208, such as a hydraulic actuator, in which hydraulic fluid may be applied to enter the pinion gear piston 221 from the actuator 208 forcing the pinion 220 into place. This may cause relative rotation between the coil 212, which does not rotate with respect to a body of a hypothetical vehicle to which the braking assembly 205 may be attached, and the disc 218. Additionally, the actuator 208 may actuate to cause the brake pad 224 to extend parallel to the rotation axis 114 to contact the brake rotor 202. For example, the brake pad 224 may be actuated by applying hydraulic fluid to fill the piston 128 and force the brake pad 224 into contact with the brake rotor 202, similarly to the mechanical braking assembly 120 as described herein.
In embodiments that include an integrated brake rotor and a single braking surface and brake pad, such as the integrated brake rotor 102 of
In embodiments, the braking assembly 205, namely, the actuator 208, may actuate the electric braking assembly 210 and the mechanical braking assembly 222 based on different criteria. For example, the electric braking assembly 210 may be actuated to inhibit rotation of the wheel 201 around the rotation axis 114 based on a first engagement criteria (e.g., actuation at a particular rotational velocity of the wheel 201) and the mechanical braking assembly 222 may be actuated to inhibit rotation of the wheel 201 around the rotation axis 114 based on a second engagement criteria (e.g., actuation at a particular rotational velocity of the wheel 201). In embodiments, the first engagement criteria may be based on a first range of rotational velocities and the second engagement criteria may be based on a second range of rotational velocities that may or may not overlap the first range of rotational velocities. For example, a vehicle may include the electric braking assembly 210 and the mechanical braking assembly 222 and may travel at a particular speed. For example, the vehicle may travel at various speeds including, for example, 30 miles per hour (MPH), 45 MPH, and 70 MPH. In embodiments, the vehicle may actuate the electric braking assembly 210 to slow the vehicle when it is operating at high speeds (e.g., 70 MPH) and/or low speeds (e.g., 30 MPH) and may actuate the mechanical braking assembly 222 when it is operating at high speeds and/or at low speeds. In embodiments, the vehicle may engage the electric braking assembly 210 and/or the mechanical braking assembly 222 when it is travelling at medium speeds (e.g., 45 MPH). The particular rotational velocities of the wheel 201 and the speed of the vehicle and ranges thereof at which the electric braking assembly 210 and the mechanical braking assembly 222 may actuate are variable.
The electric braking assembly 210 may be electrically coupled to one or more systems to regenerate electrical energy to store, for example, in a battery bank of a vehicle to which the electric braking assembly 210 is attached. That is, relative rotational motion between the coil 212 and the plurality of magnets 214, which surrounds the coil 212, may induce a current in the coil 212 that can be used to charge a battery. In some embodiments, engagement of the electric braking assembly 210, and thus inducement of current, may be based on a vehicle speed. For example, the electric braking assembly 210 may be activated only when the vehicle is operating above, for example, 50 MPH, 60 MPH, 70 MPH, etc. The vehicle speed may be determined, as one example, based on a rotational velocity of the wheel 201. In embodiments, the mechanical braking assembly 222 may engage regardless of whether or not the electric braking assembly 210 is actuated. In some embodiments, engagement of one or both of the electric braking assembly 210 and the mechanical braking assembly 222 is based on a sensed magnitude of the braking force. For example, if a user of the vehicle pushes a brake pedal with a particular level of force (e.g., a relatively high level of force), both the electric braking assembly 210 and the mechanical braking assembly 222 may engage. In embodiments, if the user pushes a brake pedal with a relatively low level of force, only one of the electric braking assembly 210 and the mechanical braking assembly 222 may engage. In such embodiments, which of the two assemblies engages may be based on a vehicle speed (as determined, for example, based on a rotational velocity of the wheel).
Referring now to
Referring to
In operation, the actuation assembly 312 actuates the piston 316 to push or pull the actuation arm 314 outward or inward, respectively. As the piston 316 moves, the actuation arm 314 makes contact with the stator 310 and prevents it from rotating with respect to the rotor coil 308. That is, the rotor coil 308 is directly coupled with the axle 306, and thus rotates with the axle 306. As the actuation arm 314 engages, rotation of the stator 310 is inhibited and an electromotive force is generated and a current is induced by the relative motion between the rotor coil 308 and the stator 310. This electromotive force tends to inhibit rotation of the axle 306 and the wheel 302. The induced current can be stored in a battery or other charge store as described herein.
Conversely, the motor/generator assembly 300 can act as a motor, generating an electromotive force that turns the wheel 302. That is, the actuation arm 314 may be engaged with the stator 310 to inhibit its rotation and an electric current may be applied to the rotor coil 308 creating an electromotive force that tends to cause the rotor coil 308, and thus the wheel 302 to rotate. Such an electromotive force may cause a hypothetical vehicle to which the wheel 302 may be attached to be propelled forward or backward depending on the direction the current is applied to the rotor coil 308.
While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications may be made without departing from the scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter.
It should be understood that the figures described herein are not necessarily to scale. However, it is to be understood that the disclosed aspects are merely illustrative and may be embodied in various and alternative forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for any aspect of the methods, systems, and devices described herein and/or as a representative basis for teaching one skilled in the art to variously employ the methods, systems, and devices described herein.
It is also to be understood that the methods, systems, and devices described herein are not limited to the specific aspects and methods described herein, as specific components and/or conditions may, of course, vary. Furthermore, the terminology used herein is used only for the purpose of describing particular aspects and is not intended to be limiting in any way.
It will be understood that, although the terms “first,” “second,” “third,” etc., may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, “a first element,” “component,” “region,” “layer,” or “section” discussed below could be termed a second (or other) element, component, region, layer, or section without departing from the teachings herein.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms, including “at least one,” unless the content clearly indicates otherwise. “Or” means “and/or.” As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof. The term “or a combination thereof” means a combination including at least one of the foregoing elements.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Various modifications of the present invention, in addition to those shown and described herein, will be apparent to those skilled in the art of the above description. Such modifications are also intended to fall within the scope of the appended claims.
It is appreciated that all reagents are obtainable by sources known in the art unless otherwise specified.
Patents, publications, and applications mentioned in the specification are indicative of the levels of those skilled in the art to which the invention pertains. These patents, publications, and applications are incorporated herein by reference to the same extent as if each individual patent, publication, or application was specifically and individually incorporated herein by reference.
The foregoing description is illustrative of particular embodiments of the invention, but is not meant to be a limitation upon the practice thereof.
This application is a non-provisional application which claims priority to co-pending U.S. Provisional Patent Application No. 62/810,686, filed Feb. 26, 2019, for “Wheel and Brake Assemblies,” which is hereby incorporated by reference in its entirety including the drawings.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2020/019934 | 2/26/2020 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62810686 | Feb 2019 | US |
