Patent Application
20250157706
The present disclosure relates generally to a modular resistor grid system that includes a modular resistor grid assembly, such as a resistor grid assembly used for resistive braking in a machine. More specifically, the present disclosure relates to a modular resistor grid system configured to interchangeably receive modular resistor grid assemblies that provide a designated or “black box” resistance. The modular resistor grid assemblies may be formed from multiple modular resistor grids and may have identical or similar electrical resistances between their respective input and output terminals despite having different sizes and different thermodynamic properties. Interchangeably coupling the modular resistor grid assemblies with a target black box resistance to a modular resistor grid system can achieve improved resistive breaking capacity in variable operating environments, among other benefits.
Resistor grid systems used for dynamic braking in machines, such as electric and diesel-electric locomotives, off-highway machines, and other heavy equipment, are well known. Typically, the resistor grid system includes a plurality of resistor elements to dissipate the electric power generated during braking of the machine as heat. Thus, the resistor grid system may supplement the friction-based brakes and minimize the wear in friction-based braking components of the machine. However, the ability of a resistor grid system to dissipate heat may be reduced based on the component design of the system, ambient conditions surrounding the machine, and the altitude of machine operation. Improved resistor grid system designs are needed to increase the longevity of resistive braking systems and to allow for maximum braking capacity under varied operating conditions.
Further, existing resistor grid systems operate in environments prone to extreme conditions such as inclement weather, rain, exposure to dust and debris, and the like. Accordingly, wet conditions may lead to DC ground faults and other shortages which reduce resistive breaking capacity. Further, current resistor grid systems fail to account for variations in machine operating conditions. Changes in altitude and corresponding changes in air density, for example, may reduce the resistive breaking capacity of current resistive braking systems due to their inability to adapt based on the target operating locale or based on changes in ambient operating conditions.
One embodiment relates to a modular resistor grid assembly. The modular resistor grid assembly includes an input terminal, an output terminal, a first plurality of resistor grids configured to couple together, and a second plurality of resistor grids configured to couple together. The first plurality of resistor grids, when coupled together, and the second plurality of resistor grids, when coupled together, are configured to interchangeably connect to the input terminal and the output terminal. When the first plurality of resistor grids connects to the input terminal and the output terminal, the first plurality of resistor grids provides a target electrical resistance between the input terminal and the output terminal. Similarly, when the second plurality of resistor grids connects to the input terminal and the output terminal, the second plurality of resistor grids also provides the target electrical resistance between the input terminal and the output terminal. Each of the first plurality of resistor grids includes a first housing and a first plurality of resistor plates disposed within the first housing. Each of the first plurality of resistor plates has a first thickness. Similarly, each of the second plurality of resistor grids includes a second housing and a second plurality of resistor plates disposed within the second housing. Each of the second plurality of resistor plates has a second thickness. Further, the first thickness is greater than the second thickness.
Another embodiment relates to a modular resistor grid assembly. The modular resistor grid assembly includes a first plurality of resistor plates disposed within a first housing. Each of the first plurality of resistor plates has a first thickness. The first housing has a first input terminal and a first output terminal. The first plurality of resistor plates is configured to provide a target electrical resistance between the first input terminal and the first output terminal. The modular resistor grid assembly also includes a second plurality of resistor plates disposed within a second housing. Each of the second plurality of resistor plates has a second thickness. The second housing has a second input terminal and a second output terminal. The second plurality of resistor plates is configured to provide the target electrical resistance between the second input terminal and the second output terminal. Further, the first housing and the second housing are configured interchangeably couple to a resistive braking system of a machine. Additionally, the first plurality of resistor plates includes a first number of resistor plates, and the second plurality of resistor plates includes a second number of resistor plates less than the first number of resistor plates. Finally, the first thickness of the first plurality of resistor plates is greater than the second thickness of the second plurality of resistor plates.
Still another embodiment relates to a method of using a modular resistor grid assembly. The method includes installing a first modular resistor grid assembly to a resistive braking system of a vehicle by coupling an input terminal and an output terminal of the first modular resistor grid assembly to the resistive braking system such that a target electrical resistance and a first watt density are defined between the input terminal and the output terminal. The method also includes operating the vehicle at a first location and moving the vehicle to a second location. The method further includes uninstalling the first modular resistor grid assembly from the resistive braking system by decoupling the input terminal and the output terminal of the first modular resistor grid assembly from the resistive braking system. Additionally, the method includes installing a second modular resistor grid assembly to the resistive braking system of the vehicle by coupling an input terminal and an output terminal of the second modular resistor grid assembly to the resistive braking system such that the target electrical resistance and a second watt density, greater than the first watt density, are defined between the input terminal and the output terminal. Finally, the method includes operating the vehicle at the second location.
This summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of the devices or processes described herein will become apparent in the detailed description set forth herein, taken in conjunction with the accompanying figures, wherein like reference numerals refer to like elements.
Before turning to the figures, which illustrate certain exemplary embodiments in detail, it should be understood that the present disclosure is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the terminology used herein is for the purpose of description only and should not be regarded as limiting.
The modular resistor grid systems including modular resistor grid assemblies having a “black box” resistance disclosed herein can interchangeably vary in thermodynamic properties and system size while providing uniform resistive breaking capacity to suit their environment of operation. In some aspects, the descriptor “black box” resistance illustrates that, from a systems or circuit perspective, the modular resistor grid assemblies disclosed herein may be connected between an input and an output and create identical resistances across the input and the output. For illustrative purposes, a first modular resistor grid assembly may have a resistance of 3 Ohms. A second modular resistor assembly may also have a resistance of 3 Ohms but have differing physical and thermodynamic properties than the first modular resistor grid assembly. However, a resistance measurement across the input and output terminal would yield only a reading of 3 Ohms for each despite these differences. In this way, despite the varying physical and thermodynamic properties, each of the plurality of modular resistor grid assemblies disclosed herein may be treated as a “black box” having a shared resistance value that enables interoperability with a modular resistor grid system.
According to an exemplary embodiment, a modular resistor assembly is configured to interchangeably, electrically couple to an input terminal and an output terminal of a machine (e.g., to an input terminal and an output terminal of a resistive braking system of a machine). In other words, one modular resistor assembly having a “black box” resistance may be removed from the machine's input terminal and output terminal, and a second modular resistor assembly having the “black box” resistance may be electrically coupled to the input terminal and the output terminal. Advantageously, in response to or in anticipation of changes in the machine's operating environment, the modular resistor assembly having a “black box” resistance may be exchanged or swapped for a different modular resistor assembly that provides different physical and thermodynamic properties but similar electrical properties and specifically an identical “black box” resistance between the input terminal and output terminal. In this way, the modular resistor assemblies having a “black box” resistance allow for a machine or a resistive braking system thereof to interchangeably adapt to changes in operating conditions without sacrificing resistive breaking capacity and with minimal changes to system architecture.
For example, and as discussed herein, multiple modular resistor grid assemblies having a “black box” resistance for a modular resistor grid system are disclosed. Each modular resistor grid assembly may include an input terminal, an output terminal, a housing, and one or more modular resistor grids. Specifically, multiple modular resistor grids may couple together to form a modular resistor grid assembly having a “black box” resistance. The modular resistor grids, in turn, include terminals, a housing, and resistor elements disposed within the housing. The resistor elements may be disposed in rows within the housing and may be connected in series or in parallel to form a conductive path between the terminals. When the modular resistor grids couple together, they form respective modular resistor grid assemblies having a “black box” resistance. In this way, by varying the structural and geometric properties of the resistor elements and associated resistor grid assemblies and components thereof, modular resistor grid assemblies of varying sizes, masses, and thermodynamic properties can interchangeably couple to the input terminal and the output terminal of a resistive braking system while the electrical resistance between the input terminal and output terminal remains the same. Further, the resistor elements may be composed of a resistor plate and insulators. By varying the number and thickness of the resistor plates, the watt-density, size, and surface area exposed for convective heat transfer associated with varied modular resistor grid assemblies having a “black box” resistance may be coupled to the resistive braking system of a machine to avoid losses to resistive breaking capacity due to changes in the environment of operation.
Specifically, the modular resistor grid assemblies having a “black box” resistance may vary in (i) the number of resistor plates disposed within their housings, (ii) the thickness and/or width of the resistor plates disposed within their housings, and (iii) the axial length of their housings. Further, a first modular resistor grid assembly and a second modular resistor grid assembly may vary in (iv) respective watt-densities of the modular resistor grid assemblies, (v) a number of modular resistor grids coupled together to form the respective modular resistor grid assemblies, and (vi) a number of resistor rows disposed within the respective modular resistor grid assemblies. Also, the first modular resistor grid assembly and the second modular resistor grid assembly may be similar and share at least one or more of (i) the same target resistance between the input terminal and the output terminal, (ii) the same radial height (e.g., size of an inner radius of the housing and/or size of the outer radius of the housing, and (iii) the general profile/form and structure of insulators within each respective housing such that the insulators may be manufactured utilizing the same base processes. Beneficially, the interchangeable quality of the modular resistor grid assemblies having a “black box” resistance and the similarities in form and structure allow for common insulator tooling, common resistor element tooling, common cooling fan (e.g., blower) assemblies, and common mounting features (e.g., frames, fan mounts, and the like) to be used across a fleet of machines. Common tooling and overlapping structural components save costs associated with fabrication, assembly, installation, and use of the modular resistor grid system.
Additionally, the “black box resistance” shared by the modular resistor grid assemblies allows for each of the plurality of modular resistor grid assemblies to variability and interchangeability couple to a modular resistor grid system of a vehicle as needed (e.g., for a specific operating environment, a modular resistor grid assembly having a particular geometry suited for the environment may be chosen and installed, and the vehicle resistive breaking systems will compatibly operate with the modular resistor grid assembly due to the shared electrical properties between one modular resistor grid assembly and another). Beneficially, and in short, providing modular resistor grid assemblies with a “black box” resistance allows for various modular resistor grid assemblies to be interchanged in a modular resistor grid system of a machine to suit changes in the machine's environment of operation. For example, at high altitudes, air density is lower than air density at lower altitudes. Accordingly, a machine operating a fan to cool a modular resistor grid assembly will provide equal volumetric flow rates of cooling air at both altitudes, however the mass flow rate of air through the high-altitude modular resistor grid assembly may be substantially less than the mass flow rate of air through the low altitude modular resistor grid assembly due to the difference in air density. Accordingly, a machine would benefit from including a modular resistor grid assembly having a lower watt-density of power dissipation and a larger axial length (e.g., surface area for heat convection) at the high-altitude location. Similarly, the machine at the lower altitude location would benefit from having a higher-watt density of power dissipation and a smaller axial length (e.g., surface area for heat convection) to achieve the same restive braking capacity while reducing machine mass and occupied space.
The apparatuses, systems, and methods disclosed herein allow for interchangeable adaptation of resistive breaking assemblies to optimize physical, electrical, and thermodynamic properties of a machine's resistive braking system based on such changes to the machine's operating environment. Further, although the interchangeable modular resistive grid assemblies having a “black box” resistance may vary in watt-density, mass, surface area for heat dissipation, and the like, they may in some respects be treated the same from systems perspective. For example, and beneficially, a resistance across the input and output terminals of different modular resistor grid assemblies having a “black box” resistance would be the same, allowing for vehicle control systems and circuits to operate with the interchangeable modular resistor grid assemblies with little to no adjustment or calibration.
A machine 100 in which disclosed embodiments may be implemented is schematically illustrated in
For the purpose of the present disclosure, in
The machine 100 may further include a set of drive wheels 108 to propel the machine 100. In an embodiment, a set of idle wheels 110 may also be provided to steer the machine 100 in different directions. Further, the machine 100 may also include an articulated chassis for steering. Together, the set of drive wheels 108 and the set of idle wheels 110 may act as the ground engaging members for the machine 100. As illustrated in
The machine 100 of the present disclosure may be an electric machine having an electric drive 112. The electric drive 112 may provide the electric power to drive various components in the machine 100. In an embodiment, the electric power may be generated onboard by a generator, alternator, or another power-generation device, which may be driven by an engine or any other power source. Alternatively, the electric power may not be generated onboard but supplied externally from an overhead conductor via a pantograph trolley, a battery, a series of capacitors, or the like to drive the machine 100.
In the illustrated embodiment, the electric drive 112 includes a power source 114, which may be an engine, for example, an internal combustion engine such as a diesel engine, a gasoline engine, a natural gas engine or the like. The power source 114 may provide an output torque at an output shaft 116 in the machine 100. The output shaft 116 may be connected to a generator 118, which may be a multiple-phase alternating current (AC) synchronous alternator. During operation, the output shaft 116 rotates a rotor of the generator 118 to produce electric power, for example, in the form of alternating current (AC). This generated electric power may be used to run a plurality of drive motors 120 coupled directly or via intermediate assemblies to the set of drive wheels 108. For the purpose of the present disclosure, the drive motors 120 may be variable speed, reversible AC motors.
A schematic of the electric drive 112 is illustrated in
A person skilled in the art will understand that the generator 118 may produce electric power in the form of alternating current (AC) power. This electric power may be supplied to a rectifier 122 and converted to direct current (DC) power. The rectified DC power may be converted again to AC power by an inverter circuit 124. The inverter circuit 124 may be capable of selectively adjusting the frequency and/or pulse-width of the output, such that the drive motors 120 that are connected to an output of the inverter circuit 124 may be operated at variable speeds. In an embodiment, a plurality of inverter circuits 124 may be disposed in connection with the drive motors 120 in the machine 100.
According to the present disclosure, the dynamic braking system 200 may include a control unit 202, which may be a combination of, but not limited to, a set of instructions, a Random Access Memory (RAM), a Read Only Memory (ROM), flash memory, a data structure, and the like. The control unit 202 may be configured to receive the operator command in the machine 100. Further, the control unit 202 may determine whether to put the machine 100 in the braking mode or not, based at least in part on the operator command. To initiate braking of the machine 100, the control unit 202 may generate a braking signal (illustrated by dotted line) for the inverter circuit 124.
The braking signal may be received by the inverter circuit 124 in the machine 100. The braking signal may carry instructions to reverse a torque polarity of the drive motors 120. This makes the drive motors 120 to act as generators, using the mechanical power in the form of rotational energy from the set of drive wheels 108 to produce electric power. This electric power may be supplied back to the electric drive 112 in the machine 100.
The dynamic braking system 200 may further be configured to provide regenerative braking in the machine 100. For this purpose, the dynamic braking system 200 may include an energy storage unit 204. The energy storage unit 204 may include a battery, a plurality of capacitors or the like disposed in connection with the drive motors 120 in the electric drive 112. As during braking mode, the drive motors 120 may produce electric power, the energy storage unit 204 may store this electric power for later use in the machine 100.
The present disclosure is applicable to many machines, for example, a large off-highway truck, such as a dump truck, which are commonly used in mines, construction sites and quarries. The machine 100 may have a high payload capability and a travel speed of a few miles per hour when fully loaded. The machine 100 may further be required to operate in a variety of environments, at a variety of altitudes, and to negotiate steep inclines in dry or wet conditions.
Typically, to halt or slow down such machines, friction-based brakes coupled to the set of drive wheels and idle wheels are used. These friction-based brakes are effective but may wear out with prolonged use. To overcome this, the dynamic braking system 200 of the machine 100 of the present disclosure may work in combination with or without these friction-based brakes. The dynamic braking system 200 may supplement these friction-based brakes in the machine 100 and thus helps in reducing the wear of such brakes.
The dynamic braking system 200 may act on the operator command to put the machine 100 in the braking mode. Specifically, the operator command may be received by the control unit 202 in the dynamic braking system 200. The control unit 202 generates the braking signal determined at least in part by the operator command. This determination or calculation may be based on various operating parameters of the machine 100, such as, the current speed, the current payload, the rate of acceleration, the desired speed and so forth.
Subsequently, the braking signal may be received by the inverter circuit 124 in the electric drive 112 of the machine 100. In the braking mode, the electric drive 112 may switch the torque polarity of the drive motors 120, which makes the drive motors 120 to act as generators. In this mode, the drive motors 120 may use the power from the set of drive wheels 108, which ultimately discharges the mechanical energy of the set of drive wheels 108 and achieves retarding of the machine 100. Further, the drive motors 120, consuming the mechanical power from the set of drive wheels 108, may generate electric power in the electric drive 112.
This generated electric power may be fed to the dynamic braking system 200 in the electric drive 112. The generated electric power, which may be in the form of AC, may be fed via the inverter 124 which converts AC electric power into DC electric power. In an embodiment, with the machine 100 having regenerative braking, a part of the generated electric power may be supplied to the modular resistor grid system 111 to be dissipated as heat and the remainder of the generated electric power may be supplied to the energy storage unit 204 for later use in the machine 100.
The dynamic braking system 200 may include the modular resistor grid system 111 disclosed herein. The modular resistor grid system 111 may dissipate some or all of the generated electric power in the form of heat.
Referring to
The modular resistor grid system 111 also includes a fan 310. The fan 310 is configured to blow cooling air through a modular resistor grid assembly having a “black box” resistance 400 in order to dissipate heat, for example, during a resistive braking mode of the machine 100. In some embodiments, the fan 310 may include a blower, a pressurized air source, a coolant delivery source, or the like. The fan 310 may include a blade assembly 312 configured to direct air towards or through the modular resistor grid assembly having a “black box” resistance 400 as the blade assembly 312 rotates. A power source 314 (e.g., a motor, battery, etc.) may power the fan 310, and a hub assembly 316 may direct air towards the modular resistor grid assembly having a “black box” resistance 400 and/or encase and protect the components of the fan 310.
The modular resistor grid system 111 includes two or more modular resistor grid assemblies having a “black box” resistance 400 (e.g., a first modular resistor grid assembly 500, a second modular resistor grid assembly 600, etc.). The modular resistor grid assembly having a “black box” resistance 400 is configured to facilitate resistive braking by receiving and dissipating power from the machine 100 in the form of heat. In some embodiments, the modular resistor grid assemblies having a “black box” resistance 400 may be formed as a single unit or may be formed from a single modular resistor grid (e.g., a single cylindrical modular resistor grid). In other embodiments, the modular resistor grid assemblies having a “black box” resistance 400 may be formed by coupling together two or more modular resistor grids (e.g., first modular resistor grid 502, second modular resistor grid 602 shown
The modular resistor grid assemblies having a “black box” resistance 400 and their respective modular resistor grids include at least one resistor element 410 disposed between the inner wall 406 and the outer wall 408 of the housing 404. The modular resistor grid assembly having a “black box” resistance 400 and/or the modular resistor grids may include two or more resistor elements 410 (e.g., a plurality of resistor elements 410) that are closely packed in a stacked configuration abutting in an end-to-end orientation. The two or more resistor elements 410 form a conductive path between an input terminal 419 and an output terminal 420 of the modular resistor grid assembly having a “black box” resistance 400. The resistor elements 410 may be uniformly arranged in the housing 404 to maintain air spaces between each other. This uniform spacing provides for flow of cooling air between the resistor elements 410 in the modular resistor grid system 111. Moreover, one or more cooling air vents may be provided in the housing 404 for circulation of cooling air in the modular resistor grid system 111.
As illustrated, the first insulator 412 and the second insulator 414 may be in the shape of a block made of insulating material such as silicon bonded laminated mica, ceramic, glass reinforced material, etc. However, other suitable materials with insulating properties may be used to form the first insulator 412 and the second insulator 414. Similarly, the first insulator 412 and second insulator 414 may be formed in a variety of shapes such as blocks, blocks separated by winged or flared connectors, arcuate shapes, round, triangular, hexagonal shapes and the like. Preferably, the shape and profile of the first insulator 412 and the second insulator 414 are configured to allow air to flow freely in an axial direction relative to the housing 404 and across a large, exposed surface area of the resistor elements 410 when assembled within the housing 404. Additionally, the first insulator 412 and the second insulator 414 may be shaped to achieve a predetermined electrical property (e.g., creepage, clearance, etc.) between conductors of the modular resistor grid assembly having a “black box” resistance 400. The first insulator 412 may be affixed to the outer wall 408 of the housing 404 by some fastening member, such as, nuts and bolts, screws, etc. The second insulator 414 may be similarly fastened to the inner wall 406 of the housing 404. The first insulator 412 and the second insulator 414 may each include one or more mounting features (e.g., apertures 418) formed therein and configured to receive one or more resistor plates 416. Further, the apertures 418 may not extend entirely through the first insulator 412 or the second insulator 414 and may be configured to receive a tip portion 424 of a resistor plate 416 and mount the resistor plate 416 between the first insulator 412 and the second insulator 414.
The resistor plate 416 may be formed of a resistive material, such as stainless steel, carbon, nichrome, tungsten, ceramics, polymeric materials, graphite, semiconductors, metal oxides, photocells, resistive inks, or any other resistive material. The resistor plate may take a variety of shapes and be contoured to increase surface area exposed to air flowing through the housing 404 for thermal convection. For example, the resistor plate 416 may be a continuous strip of resistive material such as stainless steel. The resistor plate 416 may include a body portion 421 extending along a longitudinal direction XX′ of the resistor plate 416. In an embodiment, the resistor plate 416 may also include a series of reflexed portions 422 disposed at opposite longitudinal sides in the body portion 421 of the resistor plate 416. In an exemplary configuration, the resistor plate 416 may extend a length, LR, of about 150 millimeters to about 200 millimeters along the longitudinal direction XX′. In a specific example, the resistor element 410 may have a length LR of about 175 millimeters. The resistor plate 416 may have a tip portion 424 disposed at an end 426 of the body portion 421. Alternatively, the resistor plate 416 may include two or more tip portions 424 disposed from both the ends 426. The tip portions 424 may include curved profiles configured to abut the tip portions 424 of an adjacent resistor plate 416 to be fastened together via a seem weld, clamp, binding, pin, cover, or the like. The tip portions 424 of the resistor plate 416 may be adapted to be received in the apertures 418 of the first insulator 412 and the second insulator 414. The apertures 418 may provide some clearance for movement of the tip portions 424 within. This allows for the resistor plate 416 to move in the longitudinal direction XX′ in the resistor element 410 upon thermal expansion and thermal contraction.
The resistor plate 416 may also include a thickness, T, as shown in
During a resistive braking mode, the generated electric power may pass into the modular resistor grid system 111 via the input terminal 419. The generated electric power may flow through the resistor plates 416 in the resistor element 410 of the modular resistor grid system 111, to be dissipated as heat. Specifically, the heat is generated by the body portion 421 of the resistor plate 416. This generated heat may be radiated to the first insulator 412 and the second insulator 414 and raise the temperature of the first insulator 412 and the second insulator 414 in the resistor element 410. The normal continuous operating temperature for the first insulator 412 and the second insulator 414 may be in the range of 300 to 400 degrees Celsius, according to industry standards. For short intervals, the temperature of the first insulator 412 and the second insulator 414 may reach higher values due to surges, but if the temperature rises above a critical or maximum operating temperature for extended periods of time, the lifetime of the first insulator 412 and the second insulator 414 may be greatly reduced.
Turning to
The first housing 504 includes a first input terminal 519 and a first output terminal 520 configured to connect to a modular resistor grid system 111 and/or a resistive braking system. For example, the first housing 504 may be coupled to the mount 302 and connect to the modular resistor grid system 111. In other embodiments, the mount 302 may have additional terminals that connect to terminals of the machine 100. In such embodiments, the first input terminal 519 and the first output terminal 520 may connect to a corresponding input terminal and a corresponding output terminal of a braking system of the machine 100 (e.g., to a dynamic braking system 200 or a resistive braking system of the machine 100). The first housing 504 may also include terminals 517 shown in
The first housing 504 of the first modular resistor grid assembly having a “black box” resistance 500 may also have a first axial length L1 and a first height H1 (shown in
Accordingly, in some embodiments, the modular resistor grid system 111 may occupy a volume of space roughly 1300 mm by 1300 mm by 1250 mm. As shown in
The first modular resistor grid assembly 500 includes a first plurality of first resistor elements 510 which includes a first number of first resistor elements 510. The first plurality of first resistor elements 510 and/or a first plurality of first resistor plates 516 are connected between the first input terminal 519 and the first output terminal 520. The first plurality of first resistor plates 516 may be components of the first plurality of first resistor elements 510, which may also be assembled/disposed as a first number of first resistor rows 512 within the first housing 504 of the first modular resistor grid assembly 500 (shown in
Turning to
Turning to
Also, like the first modular resistor grid assembly 500, cooling air may flow from the fan 310 in an axial direction between a second inlet 640 and a second outlet 641 of the second modular resistor grid assembly 600 and across the surface area of multiple resistor elements 410 (e.g., second resistor elements 610) within the second housing 604. The second housing 604 may also define one or more air vents or flow paths to further facilitate convective cooling of the second resistor elements 610 disposed therein. The second housing 604 also includes a second input terminal 619 and a second output terminal 620 which may be configured to couple to the modular resistor grid system 111 and/or to a machine 100 (e.g., to a dynamic braking system 200 or a resistive braking system of the machine 100). The terminals 617 shown in
Turning to
The second modular resistor grid assembly 600 includes a second plurality of second resistor elements 610 which includes a second number of second resistor elements 610. In the embodiment shown in
As shown, in some embodiments, each of the second plurality of second resistor elements 610 and/or second resistor plates 616 extend between the second inner wall 606 and the second outer wall 608 of the second housing 604. Each of the second resistor plates 616 has a second thickness T2, which may be the same for each of the second resistor plates 616 disposed within the second housing 604. The second resistor plates 616 and/or the second resistor elements 610 may also have a second width, which together with the second thickness T2, defines a second cross sectional area. The second cross sectional area may differ from the first cross sectional area. However, the total length of the second plurality of second resistor elements 616 may correspond to the second cross sectional area such that the target resistance between the second input terminal 619 and the second output terminal 620 is the same as the target resistance between the first input terminal 519 and the first output terminal 520.
Turning to
The modular resistor grid system 111 may have a target electrical resistance defined between the input terminal 619 and the output terminal 620. In this way, when the modular resistor grid system 111 is coupled to a machine 100, electric current may flow from the input terminal 619 to the output terminal 620 and the modular resistor grid system 111 may dissipate power as heat. Notably, the plurality of modular resistor grid assemblies having a “black box” resistance 400 (e.g., the first modular resistor grid assembly 500, the second modular resistor grid assembly 600, other modular resistor grid assemblies of varying shapes/sizes having the “black box” resistance and configured to interchangeably couple to the modular resistor grid system 111) may all have the same target resistance between their respective input terminals 419, 519, 619, etc. and output terminals 420, 520, 620, etc.
Specifically, the thickness and/or width of the respective resistor elements 410 within each modular resistor grid assembly 400 may be varied/designated to achieve a uniform target resistance for each of the plurality of modular resistor grid assemblies 400. In this way, the plurality of modular resistor grid assemblies 400 have a “black box” resistance such that-despite the differing size, thermodynamic properties, weight, and spatial profiles of the modular resistor grid assemblies—from an electrical systems perspective each may be viewed as a “black box” having the same resistance and thus be readily interchangeable in a resistive braking system of a machine 100. In this regard, each modular resistor grid assembly 400-600 may each have “black box” resistances which are uniform, despite having different sizes, thermodynamic properties, material compositions, etc.
For example, the first modular resistor grid assembly 500 (
In order to maintain the same target electrical resistance between the input terminals 519, 619 and the output terminals 520, 620 of the first and second modular resistor grid assembly 500, 600, the first thickness T1 (and/or first width) of the first resistor plates 516 and the second thickness T2 (and/or the second width) of the second resistor plates 616 may differ. Specifically, the first thickness T1 of the first plurality of first resistor plates 516 may be larger than the second thickness T2 of the second plurality of second resistor plates 616. Similarly, the first widths and/or second widths (e.g., the cross-sectional area of the respective resistor plates) may be varied to maintain a set resistance given the conducting path disposed in each resistor grid assembly. In this way, the target resistance between each input terminal 419, 519, 619 and output terminal 420, 520, 620 of a respective modular resistor grid assembly 400, 500, 600 may be 3.0 Ohms. In other embodiments, the target resistance may be 1.0 Ohms, 2.0 Ohms, between 3.5 Ohms and 3.8 Ohms, 4.0 Ohms, or other suitable resistance values.
By varying the size of each modular resistor grid assembly 400 and the thicknesses of the resistor plates 416 within each respective modular resistor grid assembly 400, the capacity to dissipate power associated with each modular resistor grid assembly having a “black box resistance” may remain uniform while the watt-density of each of the plurality of modular resistor grid assemblies having a “black box” may vary from one assembly to another. For example, a modular resistor grid system 111 may include the first modular resistor grid assembly 500 and be configured to dissipate 1 MW of power with a watt-density of approximately 20 watts/inch2. The first modular resistor grid having a “black box” resistance may be removed and replaced by the second modular resistor grid assembly 600. With the second modular resistor grid assembly 600, the modular resistor grid system 111 may then be configured to dissipate 1 MW of power with a watt-density of approximately 40 watts/inch2. In some embodiments, the watt density of the modular resistor grid system 111 may vary between 10 watts/inch2 and 60 watts/inch2 based on the particular modular resistor grid assembly having a “black box” resistance 400 installed/coupled to the modular resistor grid system 111.
Because the first modular resistor grid assembly 500 and the second modular resistor grid assembly 600 may be interchangeably coupled to the modular resistor grid system 111, an operator may selectively install or interchange the active modular resistor grid assembly depending on the environment in which the machine 100 is operating. This interchangeability beneficially allows the selection of optimized thermodynamic, electrical, and spatial properties tailored to current operating conditions. For example, the first modular resistor grid assembly 500, having a relatively low watt-density and relatively large surface area for heat convection, may be referred to as a “high-altitude” assembly. At high altitudes where air density is lower and mass flow rate of cooling air decreases for fan assemblies when compared to low altitude conditions, installing the first modular resistor grid assembly 500 increases the likelihood that the modular resistor grid system 111 receives cooling air over a sufficient surface area to operate at maximum resistive breaking capacity. Conversely, the second modular resistor grid assembly 600, having a relatively high watt-density and smaller surface area for heat convection, may be referred to as a “low-altitude” assembly. At low altitudes where air density increases and mass flow rate of cooling air is greater for fan assemblies when compared to high altitude conditions, less surface area for cooling may be required to operate at maximum resistive breaking capacity and mass/space can be saved by installing a modular resistor grid assembly with a smaller size (e.g., smaller axial length). Table 1 below demonstrates an example of the variety an operator may be presented with when choosing which modular resistor grid assembly having a “black box” resistance 400 to install:
Beneficially, a particular grid may be chosen to maintain full resistive breaking capacity at a specific location, while also optimizing the mass and spatial requirements of the modular resistor grid installed. These benefits may be achieved with common tooling and manufacturing processes and minimum changes (e.g., changes to thickness, width, cross sectional area of the resistor elements, changes to axial length of housing size, etc.) to overall resistor grid architecture.
While the modular resistor grid assemblies having a “black box” resistance 400, 500, 600, may be interchangeably coupled to the modular resistor grid system 111, the modular resistor grid system 111 may be configured to dissipate a predetermined amount of power as heat during the resistive breaking mode regardless of which modular resistor grid assembly 400, 500, 600 is installed. For example, the modular resistor grid system 111 may be configured to have a continuous power capacity of about 100 KW, 250 KW, 500 KW, 750 KW, 1 MW, 2 MW, 5 MW, 6 MW, 7 MW, 8 MW, 9 MW, 9.5 MW, or 10 MW. In other embodiments, the modular resistor grid system 111 has a continuous capacity of about 10 MW or greater. In some embodiments, the modular resistor grid system 111 has a continuous power capacity of about 500 kW to about 2 MW.
At step 1302, the method includes installing a first modular resistor grid assembly 500 (e.g., a first modular resistor grid assembly 500 having a “black box” resistance) to a resistive braking system of a machine 100 by coupling an input terminal (e.g., input terminal 519) and an output terminal (e.g., output terminal 520) of the first modular resistor grid assembly to the resistive braking system such that a target electrical resistance and a first watt density are defined between the input terminal and the output terminal. At this step, a machine 100 may include a modular resistor grid system 111 having a modular resistor grid assembly or a resistor grid previously/already installed. In this case, the installed resistor grid may be removed, and an operator may select an appropriate first modular resistor grid assembly 500 based on the conditions of the operating environment. Alternatively, the modular resistor grid system 111 may have no resistor grid installed. The machine 100 may have a designated first location of operation. For example, the machine 100 may be deployed to a mining site at a high altitude (e.g., 3000 meters above sea level, 5000 meters above sea level, etc.). At the high-altitude first location, the air density is much lower than air density at sea level, meaning that a fan 310 of the modular resistor grid system 111 will provide a lower mass flow rate of cooling air. Accordingly, a first modular resistor grid assembly 500 may be selected based on its properties that are advantageous for use at the high-altitude first location. For example, the first modular resistor grid having a “black box” resistance 500 as shown in
Accordingly, at this step, the first modular resistor grid assembly 500 may be chosen and installed on the resistive braking system of the machine 100. As shown in
At step 1304, the method includes operating the machine 100 at the first location. At this step, the machine 100 operates and preforms restive braking via the modular resistor grid system 111 having the first modular resistor grid assembly 500 installed. In this way, power is dissipated via the first modular resistor grid assembly 500 and cooling air is directed through the inlet 540 and out of the outlet 541 to cool the first modular resistor grid assembly 500 during operation.
At step 1306, the method includes moving the machine 100 to a second location. At this step, the machine 100 may be transported, reassigned, etc. and change its location of operation. For example, the second location may be a mining site at or below sea level (e.g., a “low altitude” location). At the low altitude second location, the air density is higher than the air density at the high-altitude location and thus the fan 310 provides a greater mass flow rate of cooling air.
The change in the air density and other environmental or operating conditions may prompt step 1308, uninstalling the first modular resistor grid assembly from the resistive braking system by decoupling the input terminal and the output terminal of the first modular resistor grid assembly from the resistive braking system. For example, at the low altitude second location, the first modular resistor grid assembly 500 having a larger first axial length L1 and a relatively large surface area for heat convection (e.g., when compared to a modular resistor grid having only 2, 3, 4, etc. rows) may not be optimized for the low altitude location. Specifically, the first modular resistor grid assembly 500 may take up excessive space and add additional weight/mass to the machine 100 than a smaller modular resistor grid assembly that would provide the sufficient cooling at the low altitude location and the same power dissipation of 1 MW. To reduce the mass of the machine 100 and increase the available space, the first modular resistor grid assembly 500 may be decoupled from the input terminal and output terminal of the resistive braking system and removed from the machine 100.
At step 1310, the method includes installing a second modular resistor grid assembly to the resistive braking system of the machine by coupling an input terminal and an output terminal of the second modular resistor grid assembly to the resistive braking system such that the target electrical resistance and a second watt density greater than the first watt density are defined between the input terminal and the output terminal. In other embodiments, such as when a machine 100 operates at a low altitude first location and is moved to a high altitude second location, this step may include coupling an input terminal and an output terminal of the second modular resistor grid assembly to the resistive braking system such that the target electrical resistance and a second watt density less than the first watt density are defined between the input terminal and the output terminal.
In embodiments where the machine 100 is moved from a high altitude first location to a low altitude second location, the second modular resistor grid assembly 600 may be chosen and installed on the resistive braking system of the machine 100. Installation may occur in a similar manner to that of the first modular resistor assembly 500. The second input terminal 619 and the second output terminal 620 are coupled a circuit of the resistive braking system, allowing the machine 100 to brake and adjust its speed by dissipating energy as heat via the modular resistor grid system 111. Additionally, at this step, the second modular resistor grid assembly 600 has a second number of second resistor plates 616 of the plurality of second resistor plates 616 disposed and/or located in the second housing 604. The second number may define the total length of the conductive path for the second modular resistor grid assembly 600. In light of the total length, the density of the second resistor plate 616 material, and the cross-sectional area of each plate, the plurality of second resistor plates 616 has a second thickness T2 (and/or a second width) which achieves the target resistance between the input terminal 619 and the output terminal 620 of the second modular resistor grid assembly 600. For example, in the embodiment where a machine 100 moves from a high-altitude location to a low altitude location, the second number of second resistor plates 616 may be smaller than the first number of first resistor plates 516. Additionally, the second thickness T2 and/or the second width may be smaller than the first thickness T1 and/or the first width. The second number of second resistor plates 616 may be provided to fill, for example, three rows in the second housing 604, the rows may include approximately 50-100 resistor plates in each row and connected in series between the input terminal 619 and output terminal 620. By disposing the second resistor elements 610 in the second housing 604, the second modular resistor grid assembly 600 may achieve a target resistance approximately between 3.1 and 3.8 Ohms and be configured to dissipate 1 MW of power while utilized in the resistive braking system. The second thickness may be about 0.56 mm for each of the second resistor plates 616. The second modular resistor grid assembly 600 may also include a second axial length L2 less than the first axial length L1 (e.g., about 400 mm, 500 mm, 800 mm, etc.) of the first housing 504 to encase and house the second number of second resistor elements 610. Given the lower surface area and size of the “low altitude” resistor grid assembly compared to the “high altitude” resistor grid assembly, the second modular resistor grid assembly may have a second watt density greater than the first watt density. For example, the watt density of the second modular resistor grid assembly 600 may be greater than 30 Watts/in2.
At step 1312, the method includes operating the vehicle at the second location. At this step, the machine 100 operates and preforms restive braking via the modular resistor grid system 111 having the second modular resistor grid assembly 600 installed. In this way, power is dissipated via the second modular resistor grid assembly 600 and cooling air is directed through the second inlet 640 and out of the second outlet 641 to cool the second modular resistor grid assembly 600 during operation. Notably, when moving from a high altitude to a low altitude, the second resistor grid assembly 600 may have a higher watt density and thus take up less space, have less mass, and have less surface air for heat convection than the first modular resistor grid assembly 500. However, given the increase in air density and increase in the mass flow rate of cooling air generated by the same fan 310, the modular resistor grid system 111 may still operate to dissipate 1 MW of power while the temperature is managed to prevent thermal degradation of the components thereof. Accordingly, a plurality of modular resistor grid assemblies having a “black box” resistance 400 may be manufactured and selected for use based on the location of the machine 100. In embodiments where a machine 100 begins in a low altitude location and moves to a high-altitude location, the second modular resistor grid assembly 600 may be installed first and replaced with the first modular resistor grid assembly 500 (e.g., installing the second modular resistor grid assembly results in an increased axial length, mass, surface area for convection, resistor thickness, etc.).
As utilized herein with respect to numerical ranges, the terms “approximately,” “about,” “substantially,” and similar terms generally mean +/−10% of the disclosed values, unless specified otherwise. As utilized herein with respect to structural features (e.g., to describe shape, size, orientation, direction, relative position, etc.), the terms “approximately,” “about,” “substantially,” and similar terms are meant to cover minor variations in structure that may result from, for example, the manufacturing or assembly process and are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the disclosure as recited in the appended claims.
It should be noted that the term “exemplary” and variations thereof, as used herein to describe various embodiments, are intended to indicate that such embodiments are possible examples, representations, or illustrations of possible embodiments (and such terms are not intended to connote that such embodiments are necessarily extraordinary or superlative examples).
The term “coupled” and variations thereof, as used herein, means the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent or fixed) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members coupled directly to each other, with the two members coupled to each other using a separate intervening member and any additional intermediate members coupled with one another, or with the two members coupled to each other using an intervening member that is integrally formed as a single unitary body with one of the two members. If “coupled” or variations thereof are modified by an additional term (e.g., directly coupled), the generic definition of “coupled” provided above is modified by the plain language meaning of the additional term (e.g., “directly coupled” means the joining of two members without any separate intervening member), resulting in a narrower definition than the generic definition of “coupled” provided above. Such coupling may be mechanical, electrical, or fluidic.
References herein to the positions of elements (e.g., “top,” “bottom,” “above,” “below”) are merely used to describe the orientation of various elements in the figures. It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure.
The hardware and data processing components used to implement the various processes, operations, illustrative logics, logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose single- or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, or, any conventional processor, controller, microcontroller, or state machine. A processor also may be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some embodiments, particular processes and methods may be performed by circuitry that is specific to a given function. The memory (e.g., memory, memory unit, storage device) may include one or more devices (e.g., RAM, ROM, Flash memory, hard disk storage) for storing data and/or computer code for completing or facilitating the various processes, layers and modules described in the present disclosure. The memory may be or include volatile memory or non-volatile memory, and may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described in the present disclosure. According to an exemplary embodiment, the memory is communicably connected to the processor via a processing circuit and includes computer code for executing (e.g., by the processing circuit or the processor) the one or more processes described herein.
The present disclosure contemplates methods, systems, and program products on any machine-readable media for accomplishing various operations. The embodiments of the present disclosure may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general-purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.
Although the figures and description may illustrate a specific order of method steps, the order of such steps may differ from what is depicted and described, unless specified differently above. Also, two or more steps may be performed concurrently or with partial concurrence, unless specified differently above. Such variation may depend, for example, on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations of the described methods could be accomplished with standard programming techniques with rule-based logic and other logic to accomplish the various connection steps, processing steps, comparison steps, and decision steps.
It is important to note that the construction and arrangement of the various exemplary embodiments is illustrative only. Additionally, any element disclosed in one embodiment may be incorporated or utilized with any other embodiment disclosed herein.
