Patent Application
20190351895
The instant disclosure relates to an all-wheel, digitized integrated electric propulsion and steering configuration for vehicles propelled with electro-mechanical devices or, with electro-mechanical devices in combination with other means of propulsion. Since many billions were spent on AVs R&D emulating human sensing physiology and humans behavior while driving a vehicle; engineers and scientists overlooked the insufficient concerns and funds-dedication to precision propulsion of the wheels and the steering process, which are the actual components that translates the sensing-information—obtained with multiple cameras, ultrasonic sensors, long and short range radars and LiDAR systems—into the vehicle mobility. The disclosure provides the answer to a seamless driving and handling of any EV, autonomous EVs, buses, heavy-duty trucks and semi-trailers by spreading the propulsion and steering task among verity of differently designed, multi-electro-mechanical devices, independently propelling and steering—with merely digitized electronic means—each individual wheel independently while integrating the propulsion and steering system, by emulating animal's four-Pedi motoric.
Level-Five AVs collapses traditional steering value chains by rendering mechanical linkages and steering wheels redundant. Because, there is no common-sense in having sophisticated sensory systems in AVs providing exclusively sensing information of the environment around the vehicle—and then translating this precise information to the wheels, with a 130 years old mechanical-gears technology. The digital, sensory and command tasks performed by the AV's ECUs is unable to communicate with mechanical gears that propel and steer the wheel, yet it easily communicates with all kind of sensors, DC-DC converters, DC-AC inverters, energy-storage units, and all electro-mechanical devices that propel and steer the vehicle's wheels.
Electric Power Steering (EPS) is today a standard fitment across most of vehicles. However, autonomous driving poses several challenges to the steering technology manufacturing community:
First, once a vehicles starts to operate without a driver, steering systems will expect to cater loss-of-assist mitigation in order to provide a safety net as and when the EPS power-pack fails to provide assist for steering the vehicle. This will therefore force steering suppliers to migrate from fail safe systems1 to fail operational systems for steering. However, the major stumbling block for the steering suppliers is NHTSA [National Highway Transportation and Safety Administration] regulatory compliance, which manufacturer are expecting some modifications to accommodate AVs steering functionality. This disclosure's integrated propulsion and steering concept should be adopted in future technology of choice because:
In other words: while all wheels are activated with differently computed propulsion power, and all wheels are steered with differently computed steering angles, it is obvious that all-wheel propulsion will take-over the power-steering function of the vehicle; while the integration of the propulsion in the steering process will provide an exceptional stability and maneuverability.
Second, autonomous driving does not require humans to drive the vehicle, in which case the use of steering wheel is made redundant. This then allows OEMs and steering suppliers to concentrate on technologies that will help either eliminate the steering wheel or allow the steering to retract to the dashboard if not required. The bottom line: OEMs realized that steer-by-wire must be the system of choice.
In short; this disclosure attempts to indoctrinate the taboos in mechanical engineering perceptions because, the inventor's philosophy is that vehicles have to be contemplated as an animal and not as a machine. Robots in the industry, should be classified as machines because robots are carrying-out one or at the most very limited, repetitive, pre-programmed functions. Yet a vehicle operates under constant changing driving conditions. Every driving mode is different than the previous one or the next one, which compels to sustain complex multi-objective optimization algorithm to calculate all possible operatives for the next move in milliseconds.
The Philosophy Behind Integrated Propulsion & Steering
The supremacy of mankind materialized about 5,500-years ago with the invention of the wheel, which outperformed evolution since there are no wheels in any known species. Yet, the first most efficient propulsion emerged 5,300-years later when Jun. 12, 1817, Karl von Drais (1785-1851) realized the first self-propelled mobility when he travelled through the streets of Mannheim, Germany with his “Laufmaschine,” the first bicycle. Human muscles create super-efficient propulsion since it is the direct result of close-to-perfection human muscle motoric physiology. The lower part of the brain—with “algorithm” precision activates only the muscles, and their electric degree of intense that is essential to propel the bicycle's pedals; then the pedal motion is transferred to the rear wheel to reach the best efficiency in any given load condition, which is the gist of this disclosure. The nanotechnology in the molecular level—engaging the precise electro-chemical process that excites only the exact number of Actin and Myosin proteins needed to perform precision contraction of the muscle—is not yet worked-out in vitro; but it eventually will become the leading technology in future science because, every bio-technology utilized in lighting, television and a long list of products, makes it many-time-over superior efficient, compared with any other technologies.
The reason the industry needed 130 years to look at a vehicle as an animal, is first because the convenience of cheap fuel, and second, because the dogma taught in engineering schools that only mechanical components in machines are reliable and provide the best alternative to operate a vehicle. The turning point emerged when AV researchers realized the necessity to emulate human physiology ‘perception of the environment’ while driving a vehicle. Yet, the “end-product” of multi-billion-dollar AV-research, translates the ‘environment perception’ into the old, traditional mechanical controlled propulsion and steering, does not make sense.
When visiting Thomas Alva Edison's museum in Fort Myers, Florida man can witness the “old time” philosophy of ‘power transfer’ when one electric motor actuates several ‘consumers’ with one leather belt. In the past—and unfortunately also in the present automobile industry—one crankshaft actuated since 1885 all “consumers” in IC (internal combustion) engines automobiles: the crankshaft rotates the: camshaft with belt or chain, to activate the valve; water pump' oil pump; power-steering pump; alternator; pollution air pump; ignition distributor shaft; AC compressor; transmission and differentials to mechanically synchronize mostly only two wheels.
In system 10 as depict in
The first philosophy behind this disclosure is the notion that propulsion and steering complement each other, which seems to be the only way to perform any perfect and stable mobility. Traditional automobile engineering, and new EVs, are constructed with propulsion and steering with no coordination between the two systems. It is obvious that propelling the wheels with one system and steering the same wheels with another is an imperfect arrangement, especially when it is carried out by mechanical means.
The second concept is to centralize and digitize-control of all components by exclusively electronic means for precision integration of the propulsion into the steering process; providing AVs the ability to precisely translate the perception of the environment around the vehicle into digitized vehicle propulsion & steering.
The third perception is to split power between multiple electro-mechanical devices to follow the steps of evolution where thousands of muscle-fibers are involved in certain motoric procedure, but a super-efficient precision is arrived at when the brain (controller, ECU in vehicles) elects only those muscle fibers [e.g. electro-mechanical devices] that are sufficient to do the job. Therefore, coupling, de-coupling and precision rotation of plurality of relatively small electro-mechanical devices while steering four wheels, is the ultimate approach to achieve optimization of efficient propulsion and steering mobility.
The fourth philosophy is that one electro-mechanical device can do limited undertaking. Add another electro-mechanical device for different task, sensors, and further relationship becomes possible. Yet, gradually adding more, differently designed electro-mechanical devices constructed to different specifications and different assignment-tasks, with individual, electronically controlled coupling and de-coupling clutches, then the number of complex inter-relationships grows exponentially.
The fifth philosophy teaches us that complex systems accommodating large number of elements that operate in coordination with one another, flinches new mode of actions. This disclosure exhibits relatively simple form of coordination between propulsion and steering, which results from interaction of multiple aggregates in non-linear behaviour. Complexity of multiple-component in non-linear system could never be predicted from just computing a single component and adding it up. Human precision complex motoric is typically acquired during very young age and becomes programmed in the lower brain with association to the cortex. Later on, most motoric undertakings are performed subconsciously through interactions of millions of neurons. The same “specific learned motoric sequence” in humans—with reliance on GPS's memorized road topography and location—may be programmed in the EV controller to accomplish specific turns and down- and up-hill maneuvers with improved efficiency. For example, when the EV faces a down-hill road, and after certain distance it changes to up-hill; with the GPS memory, the controller can calculate the best velocity down-hill to take the up-hill portion easy and efficiently. The same procedure relates to complex turns to be steered efficiently.
The sixth concept is to move into digitized controls and to throw-away the obsolete traditional mechanical gears in propulsion and steering systems. This will result in drastic reduction in weight, in manufacturing cost, and at the same time boost efficiency, precision maneuverability and safety, which will extend the vehicle driving-range, reduce components wear; and, perfectly accommodate any AV's engineering demands to translate the data collected by cameras, radars and LiDAR into a perfect propulsion & steering mobility.
The seventh concept is to completely electrify the trucking industry and pave the road to autonomous heavy-duty trucks and semi-trailers. There is a wide consensus that—concomitant to the enormous transition in the electrification of the light-duty vehicles—the trucking and buses industry has to be revolutionized as well. Diesel engines in trucks, semi-trucks and buses are to become obsolete for the extensive pollution of NOx and CO2 emission and respiratory health detriments. The damage to the environment and the expenditure of health-care will always exceed by far the unsupported claims of the trucking industry that manufacturing and operating electric semi-trailer is much more expensive than diesel. Unsupported arguments as presented infra with supported calculations.
Traditional Mechanical Gears are Obsolete in EVs
This disclosure is obviously not following the steps of engineering schools which support the notion that “bigger is always better.” As a matter of fact, up to last decade, automobile industry only rated vehicles by how fast they go from 0 to 60 mph; totally ignoring efficiency and pollution while neglecting the rest 99.9999% of time traveled. It makes no technological, economical or environmental sense to continuously operate an EV with a single or dual, 175 to 200 HP electro-mechanical device[s] when this level of power is needed only for the first few seconds of propulsion, and in acceleration modes that last only seconds.
It took IC engine engineers about 100-years to register that the classic 350 CID (5,735 cc) Chevy engine could be downsized to 122 CID (2,000 cc), and while equipped with turbo charging system (2018 Camaro), which is only engaged for intervals of seconds at start and in accelerating modes—could produce the same pep as a V8, 350 CID engines, thus pollutes 300% less, and consumes one third fuel.
Today, most vigorous R&D is in artificial intelligence (AI) technologies, which is nothing but a computer science that emulates human's perception of their environment; at the same time that vehicles with IC engines are still equipped with Electronic Control-Systems (ECUs) developed in the 1980s, for the convenience of cheap fuel, indicating that the automotive industry was too long in the technological ‘stone age.’
The Assessment of Battery-Pack Size, Weight and Cost
To follow government regulations to meet CAFE (Corporate Average Fuel Economy) requirements, automakers specific intent is to electrify by 2025 their vehicle portfolios.
At first glance into
A different approach to EVs manufacturing is presented in
The right column in
23% better efficiency results than Tesla's semi was arrived at with the semi equipped with the subject disclosure, and for enumerate reasons:
In most cases, the decision how to design a vehicle does not begin in the engineering department. The decision is made in the new vehicle showroom by sale personal, providing the information what sells. New-car customers are not interested in efficiency; only the look, the pep and the price of the car usually makes a sale. To meet buyers' demands, several manufacturers listed in
There is huge gulf in opinions about EVs design among manufacturers. Most of them believe that battery technology is the only factor to be improved and the rest of the EV has to be manufactured with the same, traditional die-cutting because, they refuse to accept the fact that EV manufacturing is eventually going to evolve as merely a computer with wheels. The EV chassis and body will be produced by robots, and the few ‘other’ electro-mechanical devices and digital computers—which are not traditional vehicles manufacturing doctrine—will be manufactured by subcontractor. When this stage evolves, it will be indicating the start of revolution in vehicle manufacturing, with the main concern—how to deal with the huge unemployment the EV era will generate.
The size of the battery-pack; the contribution to the vehicle weight and the contribution to manufacturing cost—and how the subject disclosure will contribute in reducing the size of battery-packs, and at the same time improve efficiency—is the core of this disclosure. A rigorous and thorough analysis considering battery metrics as well as vehicle design's parameters was done to decide how to reduce the weight and the cost of the battery-pack. Since personal vehicles are designed with no weight-limitations, the following battery-pack evaluations is concentrating in semi-trucks—since the size of energy-storage needed is more than 10-times larger than in cars—although the equations presented infra should apply to any EV.
The average payload carried by diesel semi-trucks for commodities from different industries is up to 17,300 Kg. The starting point is the fact that Class 8 semi-trailer has to comply with federal requirements of 36,364 Kg GVW; consisting of (i) tractor-truck 8,600 Kg; (ii) empty trailer 6,200 Kg; (iii) battery pack determined weight; and (iv) the size of the payload. The semi-truck empty weight Wv is about 14,800 Kg. Cummins X-15 engine and transmission weight about 1,750 Kg; and differential gears about 400 Kg. Then, a diesel ‘empty weight’ without gears is about 12,650 Kg. Four-motors in Tesla's semi-truck weight 35 Kg.×4=140 Kg. and four differentials about 200 Kg. Then, the electric semi-trailer empty weight Wv should be considered as: 12,990 Kg. The only variable to determine the payload is the battery-pack weight Wbp:
(WLoad)=Wt−(Wbp+Wv)=36,364 Kg.−(Wbp+12,990 Kg); Eq. 1.0
then:
W
Load=23,374 Kg.−Wbp Eq. 1.1
when:
Wbp is the battery-pack weight; and WLoad is the permissible load of 36,364 Kg. Theoretically, the maximum payload is 23,374 Kg., less the battery-pack weight.
EP energy, battery-pack size depends on the energy density in Wh/kg. One of the leading battery used in EVs is Panasonic's 3.2 Volt, Lithium Ion battery: LiFePO4 model NCR18650B with specific energy density of 243 Wh/kg. Lithium batteries contain much lower energy-density than petrol 12,889 Wh/kg, and hydrogen 39,443 Wh/kg. But, battery-to-wheels efficiency is 85%, which includes battery discharge efficiency of 95% and a drive-train efficiency, e.g. batteries propelling electro-mechanical devices are several times over more efficient than IC engines, with 20-28% power reach the wheels. In hydrogen fuel-cell only 36% reach the wheels. Electric Semi-truck will have to meet certain performance requirements at a reasonable cost of operation in order to be a practical alternative to existing diesel semi-trucks. Based on standard dynamics of motor-vehicles, including light- and heavy-duty vehicles up to semi-trucks; to estimate the energy-pack EP size in kWh, the vehicles have to meets dynamic requirements as presented in Eq. 2.0 infra:
ρ=density of air (1.2 kg/m3)
Cd=Coefficient of drag (0.23-0.63)
A=frontal area of the vehicle (2.8-7.2 m2)
Crr=coefficient of tires rolling resistance (0.0005-0.01)
g=acceleration due to gravity (9.8 m/s2)
Wr=gross on-road vehicle weight (GVW) maximum 36364 Kg. for semi-trucks
Z=the road gradient (r/100)
r=the percentage road grade
tf=the fraction of time the vehicle spends at a road grade of r %
ηbw=battery-to-wheels efficiency 85%, discharge efficiency 95%, drivetrain efficiency 90%
ηbrk=brakes efficiency 97%
ν=average velocity for trucks (m/s) (mph); (16-21); (36-47)
νrms=root-mean-square of the velocity for trucks (m/s) (mph); (19-24); (43-54); and
Each of the above parameters is cast as truncated multivariate Gaussian Distribution (truncated within the limits of future projections and known max/min values as depict in
Based on distributions of variables, a standard simulation test considering the mean values of an output, the distribution of output values, and the minimum/maximum output values brought the following results:
Tesla claims its electric semi-truck achieves 2 miles/kWh. This is probably correct when driving downhills. Tesla's tractor power-train consists of four-192 kW motors and gear assemblies taken from Tesla's model 3. EPA test records confirms that Tesla Model 3 with a single 192 kW motor achieves about 6 Km/kWh with about 1,773 Kg curb weight, and Cd=0.36. Tesla's semi-truck definitively produces much lower than 3.2 Km/kWh results because:
Applying the EP energy results to 480- and 960-Km traveled distance; then, fully loaded semi-truck will consumes 470 kWh, and 940 kWh respectively. The WP Battery-Pack Weight calculations are set forth as follows:
SP=uses the Panasonic's NCR18650B cell with 243 Wh/kg as current.
To calculate limit payload, the above weights are inserted in Eq. 1:
W
Load=23,374−1,930˜21,500 Kg, with 470 kWh battery-pack; Eq. 1.1
W
Load=23,374−3,870˜19,500 Kg, with 940 kWh battery-pack. Eq. 1.2
CostP, the battery pack cost: After calculating the battery-pack required energy and weight for Class 8 semi-trailer, the cost is given as follows:
CostP=EP×CostkWh Eq. 4.0
The cost of batteries based on several prices available in the market is assumed to have a current mean value of $100/kWh.
CostP=470 kWh×$100=$47,000 for 480 Km range; and Eq. 4.1
CostP=940 kWh×$100=$94,000 for 960 Km range. Eq. 4.2
For beyond current Li-ion batteries, it is assumed to be at mean cost of $80/kWh with a minimum value of $50/kWh (see Bloomberg's BNEF estimate in
Silicon is leading in battery research for two peerless advantages:
To make useful sense of this disclosure, the future social-economic considerations were scrutinized before drafting the disclosure since automobiles in particular, are devices of culture and behavior, not just economics. Both culture and behavior can change quickly for the following reasons:
Defeating Electric Motors Inefficiencies & Cost
IC engines waste most of their energy they consume; only 28% in diesel and 20% in gasoline engines get to the wheels.
Most electro-mechanical devices are designed to run at 50% to 100% of rated load; maximum efficiency is usually near 75% of rated load. The specific example of Motor #3 in
Unfortunately, drive-train design in most EVs listed in
How far efficiency can go was demonstrated 2009 by VW with the XL-1 concept-car, first presented in the 2013 Geneva automobile show. In addition to its super-aerodynamic (Cd=0.189); its light-weight carbon-fiber reinforced polymer (CFRP) which facilitates only 1,749 Lb. curb weight, and its hybrid propulsion of two pistons, 800 cc diesel engine, producing 50 HP with an electric-motor that adds 27 HP; brings about the impressive efficiency of 280 to 313 mpg, more than twice the average current EVs. In full power mode, the XL-1 can also run 125 mph. The attainment relating to the subject disclosure is by virtue of the fact that cruising in a windless highway at 62 mph (100 km/h) with only 8.3 HP supports the philosophy that most of the time, 175-200 HP electro-mechanical devices are inefficient.
Synchronous motors are rated with better efficiency than induction motors attributable to their permanent magnets in the rotor, while induction motors consume part of the current's energy to create the rotor's magnetic field. Yet, synchronous motors have many “side effects” and high price that diminishes their efficiency issues. Synchronous-motors are very expensive; they overheat, which calls for an extensive water-cooling system, especially with 175 to 200 HP and larger motors. Torque ripple and rotor skew produces annoying vibrations, similar to the annoying vibrations in high compression IC engines. Manufacturing synchronous motors with Neodymium is very expensive, and dependable on monopolized supply, which could lead to dis-economy.
Induction motors are very simple, require no ‘rare-earth-elements,’ are robust, air-cooled, and cost a fraction of synchronous motors. Tesla's best-selling model S is equipped with induction motors. The German magazine “Das Elektroauto & E-Mobilitats-Portal” reports that in March 2019 that the Tesla Model S is sees by “Schwake” [German Blue Book] as a three-year-old with 60,000 kilometers “at a considerable 60% residual value [considering the Model S has an induction-motor] while Porsche Panamera stands at 57.4%.”
In spite of induction-motors' lower-efficiency, power distribution among four-pairs of electro-mechanical devices as depict in system 10 (
Electro-mechanical devices operate with over 90% efficiency when mechanical losses during transmission of power to the wheels are curtailed, which predicts that EVs are great potential in reducing transportation's energy demand. EVs are likewise envisioned to play a significant role in the future of personal mobility and central role in transformation of energy; especially after car-sharing will become the norm. But to achieve the energy turnaround, BEVs must be much more efficient.
To justify an EV design with single electro-mechanical device, all kind of Intelligent Motor Controller (IMC) in the market, and in the patent application process, claim to have solved efficiency problems in electric motors by utilizing microprocessors to monitor motor load and accordingly match motor torque to motor load—maybe in laboratory testing. The process is reducing or increasing the voltage to the AC terminals and at the same time lowering or elevating the current to bring the motor to operate within ‘High-Efficiency Range.’ Unfortunately, IMC provides limited efficiency improvement for a single electro-mechanical devices because, for substantial part of traveled-time, EVs are operating under low load conditions; and Electro-mechanical devices operate inefficient at low and at high angular speed (RPM). The same problem take place at low power output levels, e.g. below 30% rated load and beyond the point of ‘break-down torque.’ Design and mechanical limitations of electro-mechanical device cannot be resolved merely by electronic means. A sophisticated IMCs designed and equipped with all electronic gadgets could not possibly maintain efficient propulsion with a single electro-mechanical device through all driving modes; in every possible vehicle speed, and load situation.
If emulating human physiology to create AI (artificial intelligence) is so widespread, then why human's and certain mammals' motoric physiology is not considered in manufacturing EVs?
In principle, the decisive difference between this disclosure and other EV designs is the notion that not all electro-mechanical devices have to be engaged in the propulsion and steering all the time. It took engineers many decades to realize that running power-steering pump all the time is extremely inefficient. Today's norm is EPS that assist steering only when the driver moves the steering-wheel. If all muscles, by humans and animals, would be in motion all the time, when only the legs are used to walk, humans and animals would be sleeping every 2-hours to “charge their batteries.” The concept of this disclosure is a design of a multiple, distinctively designed electro-mechanical devices, participating most of the time only in their highest efficiency range of propulsion as depict in
This intricate mechanism is designed to preserve small portions of battery-pack energy that adds-up, especially when a vehicle is driven for several hours. This additional energy saved by running a vehicle much more efficient, goes a long way.
It was tested and proven many times over that three fundamental factors affect most of the efficiency in vehicles with IC-engine: 12% for the vehicle's aerodynamics; 22% tires rolling-resistance; and 59% for IC-engines inefficiency. Aerodynamics is a vehicle design issue—in particular, but not limited to the frontal area—which is not a part of this disclosure. The 22% tire rolling resistance and tire dragging, as well as inefficiencies of electro-mechanical devices in certain loads and angular velocities will be drastically reduce with the application of this disclosure, which in addition will ease trucking maneuverability and overcome manufacturing cost barrier of semi-trailers. This disclosure will reduce the battery-pack seize, weight and cost; and at the same time increase the payload capacity.
The concept that electro-mechanical devices operate at over 90% efficiency is only partially correct because it only materializes under specific loads and during specific angular speeds as depicted in
The big advantage of electric-motors over IC engines is the ability to design infinite electro-mechanical devices to fit a diversity of specifications. The industry world-wide utilizes almost only electric power; and therefore, IC engines numbers in the industry are fractional because of their narrow torque output, narrow efficiency range, low durability and cost for having multiple moving parts in all directions. IC engines were only manufactured for the extremely low price, and high energy content of gasoline. Yet, the wider range of efficiency in electro-mechanical devices is not enough to operate an EV with a single electro-mechanical device because it cannot operate efficiently without a transmission across the range of zero to 90 mph and under variable loads. Several manufacturers who built EVs with a single motor are introduced in the model years 2019-2020 EVs with 2-motors: Tesla (first Model S came with one motor), VW I.D. BOOMZZ, Audi e-Tron and Jaguar I-Pace, for engineers realized that distributing power among all wheels leads to better efficiency and stability of the automobile. However, the two motors are not equipped with de-coupling mechanism, and therefore they consume energy all the time when the vehicle is in motion, while the subject disclosure engages only these electro-mechanical propulsion devices that will deliver the best efficiency results.
In consideration of the relatively low load consumption during driving in real world environment, most driving-modes after start are not within the optimum efficiency range, especially when a single electro-mechanical device is utilized. The solution must be a distribution of the vehicle's power demand—in different driving mode—between several electro-mechanical devices, designed with different ‘high-efficiency range of operation.’ Controller 100 [in
Controller 100 may be programmed to start propulsion with all electro-mechanical devices with 100 kW power to accelerate the vehicle from zero to 100 Kph in less than 5 seconds, which solves the problem EVs No. 3, 4 and 5 in
De-coupling electro-mechanical devices promotes efficiency, prevents overheating, and components wear-away. 5 to 10 kW electro-motors cost less than 5% of synchronous 130-kW motor with all attachments. The same applies to small DC-DC converters; and DC to AC inverters. The reason for low prices: small electro-motors and small electronics are manufactured in millions as they are used in diversity of technologies.
Trace 150 in
It is to be understood, however, that electro-mechanical devices 53, 54 and 57, 58 are not “pairs” although they operate the same joint shaft. Electro-mechanical devices 53, 54 and 57, 58 may be constructed with different design and specification. Electro-mechanical devices 53, 54 and 57, 58 that are on the right side of the vehicle are “paired” with electro-mechanical devices 51, 52 and 55, 56 that are on the left side of the vehicle, respectively. Because electro-mechanical devices pairs may have the same design and specification, they are engaged in propulsion at the same time except in precision turning modes—for example in tight parking conditions—when controller 100 disables one of the wheels, and slowly activates the other three wheels, using the non-operating wheel as pivoting axis.
Controller 100 may elect to de-couple electro-mechanical devices 53, and/or 54—or any other electro-mechanical devices in system 10—when:
In
As reliance on Einstein's theory, the actual operative sequence of dog-clutches—coupling and de-coupling of each individual electro-mechanical devices—is illustrated in
When dog-clutches have to be de-coupled as presented in
To overcome the sluggish start as mentioned supra with EVs No. 3, 4 and 5 in
Two systems, as detailed below, are integrated in one another for much better vehicle dynamics, stability, and exceptional handling and efficiency:
Improving Traditional Inefficiencies in Vehicle Dynamics
Two traditional engineering concepts in current EVs are the paramount contribution to vehicles inefficiencies:
EPA motor vehicle's Federal Test Procedure is a dynamo-meter driving, which is not a real-world driving environment since in the real world, vehicles don't drive only strait forward as on a dynamo-meter. The scenario of mechanical steering inefficiency is unaccounted for in dynamo-meter testing because during turning procedures, on the road, three tires are dragged to different degrees, especially the two rear ones, and especially in short-radii turns. Cd [Coefficient of drag] and the vehicle weight are entered in the dynamo-meter's calculations, yet, the consideration that are ignored are four tires side-slip in their contact-patch, the deformation affecting all four tire carcasses caused by cornering shear-stress-forces and rear wheels dragging. The energy lost in mechanical steering affects EVs efficiency the same way it affects IC engine vehicles, which dramatically curtails the driving range; and, wheel dragging diminishes life expectancy of tires.
A layout of a traditional fixed rear-wheel suspension (
Since traditionally only the front wheels are steerable, a traditional layout of front-wheel suspension (
The fact that AWD (all-wheel drive) system provides partial solution for better dynamics and road stability improvement was the first choice by EV manufacturers who utilized one electro-mechanical device in the rear axle, and one electro-mechanical devices in the front axle, coupled via differentials to four wheels and are engage in the propulsion at all times the vehicle is in motion. AWD systems that greatly improve vehicle dynamics were manufactured in limited numbers for their economic expense, and massive mechanical components that caused the vehicle to ‘gain weight,’ and the need for bigger engines. However, AWD systems faded away, for being heavy, costly and inefficient.
The next step in improving stability and efficiency in EVs is the incorporation of single electro-mechanical device inside the wheel. Protean Electric in Michigan claims to improve stability and efficiency in EVs by incorporating a single electro-mechanical device inside the wheel, as represented in
A sophisticated, mechanical AWD architecture manufactured by Audi, a subsidiary of VW, assists the steering to a certain degree. However, this ‘Quattro’ system (
Audi engineered a different version of AWD. It is a hybrid AWD system (
The Ultimate Integration of AWD & AW-Steering
The concept of making vehicles turn better by steering all four wheels has inspired engineers for decades. United States Army experimented with all-wheel-steering jeeps during World War II. Currently, BMW's ‘Integral Active Steering’ featured on the 7-Series and 5-Series, Infiniti (in their G and M cars), the 2014 Acura RLX, and Renault (on the Laguna) are the ones that make use of this technology.
In 2014, Infiniti Q50 was the market's first “steer-by-wire” vehicle, meaning there's no mechanical connection between the steering-wheel in your hands and the wheels on the street. “Turning the steering wheel sends just electronic signals to the steering force actuator, which sends data to the electronic control unit, which forwards it to the steering angle actuator, which turns the wheels” [according to Nissan specs information]. Steering response is quicker and more precise than in a mechanical setup. The results are quicker and more precise steering response, keeps vibrations from the road from annoying the driver, and improves the car's active lane control system. Electronic control includes a car's lane control system, which steps in when the driver drifts out of his lane. The system can adjust steering by electronic means instead of mechanical force, which requires less work.
‘Steer by wire’ cuts the vehicle's weight since no mechanical gears are utilized, which boost efficiency; it make it easier and cheaper to produce left- and right-hand drive versions of the car; it's an easy jump to systems that can be used by drivers who are paralyzed or have other handicaps; it reduces maintenance cost, and creates designing AVs a lot easier.
‘Steer by Wire’ option was initially not welcomed by all drivers because:
Back to evolution; most living species are controlling their motoric “by wire” (brain-neurons-muscles). Humans are at the top of the list for their muscle control precision (speech, piano and violin playing.) However, motoric “by-wire” was also utilized by very primitive species that no longer exist, including dinosaurs who lived over hundred million years ago and moved their huge bodies with muscles actuated “by wire.” If it was not safe during 2.5 billion years of evolution, species who carry motoric “by-wire” would have disappeared and replaced by species with better systems. It did not materialize, which makes NHTSA's arguments that “by wire” is unsafe without merit; considering steer-by-wire—approved by FAA—is the norm in aviation for decades. A pilot cannot stop in midair to fix his steering.
The instant disclosure relates to an integrated all-wheel electric propulsion and steering, which may be applied to any class of vehicles—with two or more wheels—in infinite configurations. The comprehensive aspects of this disclosure suggest that EV manufacturers should throw-out all mechanical assemblies utilized in traditional automotive engineering; skip the design stage of manufacturing EVs in admixture with IC engines; and design vehicles propelled only with electro-mechanical devices, and with battery-pack or fuel-cells as energy supply.
This disclosure comprises of plurality of electro-mechanical embodiment, sharing a joint shaft in series, which comprises the basic propulsion aggregate that propels each wheel, with or without reduction gear[s], which is connected with or without a drive-shaft directly to each, independently propelled wheel instead of a speed changing transmission and/or a differential assembly. Each electro-mechanical propulsion device may have its own individual DC-DC converter; and may have its own DC to AC inverter. If DC motor is utilized in any section of the design, then no inverter is necessary. To secure precise diverse torque and angular speed among each individual electro-mechanical device that is active, the controller may actuate all or less than all electro-mechanical devices to reach fast response from stop position to the desired propulsion speed. After gaining sufficient kinetic energy, the controller may de-couple certain motors, and in any given speed and load, actuate the motors that were designed to operate most efficient in that specific speed range and load.
Coupling and decoupling electro-mechanical devices in and out of the vehicle's propulsion process, is carried out by electronic means with an individual dog-clutch for each electro-mechanical propulsion device. If one or more of the propulsion motors are utilized with no dog-clutches—as depict in
Four-wheel steering systems comprises of 4 electro-mechanical devices, where each system is assigned to specific wheel. This small electro-mechanical, wheel-steering device is installed on the vehicle's frame and is connected through a tie-rod and a wheel-position sensor to the knuckle's steering-arm of each wheel. Each wheel-position sensor acts also as a traditional tie-rod-end, and at the same time registers and informs the controller of the actual angular-position of the wheel.
During steering modes, the controller integrates the propulsion into the steering systems by applying different speed to each wheel to perfect the steering process and substitute the power-steering undertaking. Each wheel-position sensor, in any given point and time, sends ‘by wire’ a continuous, precise information about the instant position of each wheel, with which information the controller's data base computes the precise [mostly different] angle and speed for each wheel; and during any speed and load conditions. At the same time, the controller actuates each wheel-steering motor to bring each individual wheel to the precise calculated angle for optimum steering to meet the driver's [or the AV ECU's] set turning angel via the steering-wheel sensor.
A control logic, which may comprise of software, may be stored in the controller's memory as computer-readable memory to receive information from multiple sensors; process information received, and precisely, in conformity with the program stored in the controller, executes a coordinate the integration of propulsion and steering. This logical operation of all four wheels transpires by actuating precise power, torque, speed and proper angle of each wheel—rather than only two wheels in the front or the rear—to accomplish overall traction stability with no wheel dragging, and thus, enhanced maneuverability, safety and optimal efficiency.
This disclosure provides all the safety and stability benefits of mechanical AWD and mechanical AW steering without the “side-effects” of imperfect handling control; poor stability and maneuverability; unnecessary weight; poor efficiency; excessive tire wear; and high manufacturing cost caused by multiple redundant mechanical gears. In addition, with electronic precision control of power, torque, speed and precise position of each wheel, vehicle performance results in catlike (Cheetah-like) handling—resembling a super-efficient model of man-bicycle propulsion efficiency—by consuming the least energy for better efficiency, and at the same time satisfying propulsion demand. This form of precise calculated energy consumption would provide much longer driving range in one charge, and with up to 50% smaller battery pack, 50% off manufacturing cost; and 50% less weight.
Various other features and advantages will be made apparent from the following detailed description and drawings.
The drawings illustrate embodiment presently contemplated for carrying out the invention. In the drawings:
Various other features and advantages will be made apparent from the following detailed description and drawings.
The embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosure embodiment can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular component[s]. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as variously employ the present invention. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiment that are not explicitly illustrated or described. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular application or implementation.
Referring now to the drawings wherein like reference numerals are used to identify identical components in the various views.
Digitized, Awd-System with Differently-Designed Motors
In various embodiment of this invention, the AWD propulsion segment of system 10 is configured to be incorporated into various types of vehicles, including but not limited to, automobiles, buses, light-duty trucks, semi-trailers, commercial and industrial vehicles such as mining and construction equipment, marine craft, aircraft, off-road vehicles, and personal carrier vehicles.
Propulsion system 10 may include a singular, or divided energy storage-system 12, with front energy storage 14 and rear energy storage 16. Each energy storage unit 14, 16 may have four positive terminals that are directly connected to each individual bi-directional DC-DC Converter, 21, 22, 23, 24, 25, 26, 27 and 28. Each energy storage unit 14, 16 may also have four negative terminals that are directly connected to each individual bi-directional DC-DC Converter, 21, 22, 23, 24, 25, 26, 27 and 28. Each of the energy storage units 14, 16 may have a separate or an integrated power management energy storage system [not shown], which may be configured as a battery management system. According to another embodiment, DC-DC converters 21, 22, 23, 24, 25, 26, 27 and 28 are bi-directional buck/boost voltage converters.
In energy storage units 14, 16, within system 10, sensors 30, 40 may be provided to monitor and calculate the state-of-charge of energy storage units 14, 16. According to one embodiment, sensors 30, 40 may include voltage and current sensors configured to measure the voltage and current of first and second energy storage units 14, 16 during operation of system 10.
According to various embodiment, first and second energy storage units 14, 16 may include one or more energy storage or energy producing devices such as batteries, ultra-capacitors, photovoltaic cells, flywheels, fuel cell or a combination of all five components, in various percent of their representation within each energy storage units 14, 16. Other embodiment may be where energy storage units 14, 16 incorporate ultra-capacitors with numerous capacitor-cells couple to one another, where every single capacitor-cell may have a capacitance between 500 and 3000 Farads—or greater. Ultra-capacitors offer nearly instantaneous power bursts during periods of peak power demand, therefore they may be implemented as secondary energy source that complements primary sources with batteries that suffer fast deterioration when repeatedly providing quick bursts of power; and since traditional battery energy storage have problems supporting high-power features—such as frequent start-stop vehicle applications, especially at lower temperatures—a secondary energy source with ultra-capacitors may be utilized to overcome this limitation.
In different embodiment, first and second energy storage units 14, 16 may be high power battery, with density more than 800-Wh/Kg. Other embodiment may be where energy storage units 14, 16 integrate high density batteries detailed above, in combination with several ultracapacitors.
In other embodiment, first and second storage units 14, 16 are a low-cost lithium ion battery. Alternatively, first and second storage units 14, 16 may comprise of a Silicon or Magnesium-anodes in Lithium-Sulfur battery; Sodium metal hydride battery; a Sodium Sulfur battery; a Nickel metal hydride battery; a Zinc-air battery, a Lead-Acid or any other combinations of low-constituent battery.
Propulsion system 10 may include: four bi-directional DC-DC converters 21, 22, 23 and 24, as integral components of the propulsion of the front wheels; and four bi-directional DC-DC converters 25, 26, 27 and 28, as integral components of the propulsion of the rear wheels, which are coupled across the positive DC link 20 and link 29 in the front and the rear bi-directional DC-DC converters respectively. The negative link begins in energy storage units 14, 16, and is coupled on the negative side of each component in system 10.
System 10 may include front left bi-directional DC-DC converters 21, 23 that may be connected across the positive and the negative DC link with DC bus 31 that may be connected to voltage sensor 35 to monitor the bus voltage. Bi-directional DC-DC converters 22, 24, 25, 27, 26 and 28 may maintain the same set-up as bi-directional DC converters 21, 23 respectively; that is, DC bus 32, 33 and 34 may be connected in parallel with a separate voltage sensor 36, 37, 38 to monitor the voltage in DC bus 32, 33 and 34 respectively.
To reduce the number of components in system 10; a different embodiment may be fitted where the front and rear energy storage units 14, 16 may be equipped with specific batteries that the respective bi-directional DC-DC converters may be left out. This will simplify production and reduce overall production cost. In such embodiment, a solenoid may be provided to selectively couple energy storage units 14, 16 to the respective DC bus.
All bi-directional DC-DC converters 21, 22, 23, 24, 25, 26, 27 and 28, when in use, are configured to convert one DC voltage to another DC voltage either by bucking or boosting the DC voltage. According to one embodiment, each bi-directional DC-DC converter 21, 22, 23, 24, 25, 26, 27 and 28 includes an inductor coupled to a pair of electronic switches and coupled to a pair of diodes. Each switch is coupled to a respective diode, and each switch/diode pair forms a respective half phase module. Switches may be isolated gate bipolar transistors (IGBT), metal oxide semiconductor field effect transistors (MOSFET), silicon carbide (SiC) MOSFET, gallium nitrite (GaN) devices, bipolar junction transistors (BJT), and metal oxide semiconductor-controlled thyristors (MCT).
In system 10, both energy storage units 14, 16 may be coupled via DC bus 31, 32, 33 and 34 to all electro-mechanical device or any other combination of partial loads. The controller may actuate any number of electro-mechanical devices in any driving mode, speed or load conditions, using multi-objective optimization algorithm to determine which of the electro-mechanical device configurations would consume the least Kw in any given driving mode to reach the best, most efficient propulsion.
In one embodiment of system 10, each DC to AC inverter 41, 42, 43, 44, 45, 46, 47 and 48 includes six half phase modules that are paired to form three phases, with each phase is coupled between the positive DC links 20, 29 of the DC bus 31, 32, 33 and 34 and the overall negative links of system 10.
Each electro-mechanical device 51, 52, 53, 54, 55, 56, 57, and 58 includes a plurality of winding coupled to respective phases of its respective DC-to-AC voltage inverter 41, 42, 43, 44, 45, 46, 47 and 48. The arrangements and design of the electro-mechanical devices 51, 52, 53, 54, 55, 56, 57, and 58 is limitless. Electro-mechanical devices 51, 52, 53, 54, 55, 56, 57, and 58 may either be a variety of AC motors, DC motors, fraction motors, and/or alternators. It is contemplated thus, that three-phase inverters 41, 42, 43, 44, 45, 46, 47 and 48 described herein may utilize any number of phases in alternative embodiment.
According to other embodiment, system 10 could be configured as genuine electric propulsion and steering. Alternatively, system 10 could be configured in a hybrid electric vehicle (HEV) propulsion system, which also includes an IC engine [not shown], coupled to electric propulsion system by mean of shared transmission [not shown]. System 10 could be configured in as fuel cell electric vehicles (FCEV) propulsion system, which also includes fuel cell [not shown] that may be coupled to different design of energy storage unit 14, 16.
Propulsion and steering system 10 may include geared power-transmissions [not shown in detail], 65, 66, 67 and 68 coupled to four joint shafts 61, 62, 63 and 64 that may be shared by two electro-mechanical devices when actuated by controller 100. The four-geared power-transmissions 65, 66, 67 and 68 [not shown in detail], may be constructed as single or multi-gear drive assemblies; toothed belt drive; chain drive assemblies or combinations thereof, according to innumerable embodiment. According to other embodiment, four geared power-transmissions 65, 66, 67 and 68 [not shown in detail], may be configured as electronic-variable transmission (EVT) that couples the outputs joint shafts 61, 62, 63 and 64 of electro-mechanical devices 51, 52, 53, 54, 55, 56, 57, and 58 to an internal planetary gear [not shown]. In operation, electro-mechanical devices 51, 52, 53, 54, 55, 56, 57, and 58, may be operated interchangeably over their specific high-efficiency range of bi-directional speed, torque and power commands to minimize energy loss and maintain high degree of overall system efficiency while system 10 is operating in either charge depleting (CD) or charge sustaining (CS) mode of operation.
The power outputs of four geared power-transmissions 65, 66, 67 and 68 are coupled directly to each corresponding driveshaft 71, 72, 73 and 74 of the vehicle since no differentials are necessary in the electric AWD propulsion and steering of system 10.
Controller 100 that runs and operates System 10 is connected to all eight bi-directional DC-DC converters 41, 42, 43, 44, 45, 46, 47 and 48 by control lines 15, 17. In one embodiment, control lines 15, 17 may include a real or virtual communication data link that conveys the voltage commands to the respective bi-directional DC-DC converters 21, 22, 23, 24, 25, 26, 27 and 28. Through appropriate control of switches in the front bi-directional DC-DC converters 21, 22, controller 100 is configured to boost voltage of first energy storage unit 14 to higher voltage and to supply the higher voltage to DC bus 31, 32 during the various modes of propulsion. Likewise, through appropriate control of switches in the front bi-directional DC-DC converters 23, 24, controller 100 is configured to boost voltage of first energy storage unit 14 to higher voltage and to supply the higher voltage to DC bus 31, 32 during various modes of propulsion. In the same way, through appropriate control of the switches in the rear bi-directional DC-DC converters 25, 26 controller 100 is configured to boost voltage of second energy storage unit 16 to higher voltage and to supply the higher voltage to DC bus 33, 34 during various modes of propulsion. Likewise, through appropriate control of the switches in the rear bi-directional DC-DC converters 27, 28 controller 100 is configured to boost voltage of second energy storage unit 16 to higher voltage and to supply the higher voltage to DC bus 33, 34 during the various modes of propulsion.
Additionally, during charging or during regenerative mode of operation, controller 100 is configured to control switching bi-directional DC-DC converters 21, 22, 23 and 24 in the front of the vehicle; and bi-directional DC-DC converters 25, 26, 27 and 28 in the rear of the vehicle to buck voltage of DC bus 31, 32 in the front and DC bus 33, 34 in the rear and supply the bucked voltage to the respective first and second energy storage units 14, 16.
To fit this integrated all-wheel electric propulsion and steering in any vehicle, system 10 may be implemented in infinite configurations. The variables may include the number and design of the electro-mechanical devices, the power and torque rating, and the design of the algorithm inside the logic data base of controller 100. System 10, as depict in
In all propulsion and steering modes, controller 100 is coupled individually to all four DC to AC voltage inverters 41, 42, 43 and 44 in the front of the vehicle through control lines 49. Controller 100 is also configured to control the half phase modules of the front DC to AC voltage inverters 41, 42, 43 and 44 to convert the DC voltage on DC bus 31, 32 to AC voltage for supply individually to each electro-mechanical device 51, 52, 53 and 54, as part of the front propulsion. Starting propulsion from zero, changing speed in acceleration or deceleration, controller 100 may increase or decrease the voltage and increase or decrease the frequency modulation in selected DC to AC inverters 4142, 43 and 44, through lines 49, with which the revolutions—in electro-mechanical devices 51, 54 or 52 and 53, or in all four electro-mechanical devices together—are boosting or bucking to increase or decrease the speed of the vehicle.
Similar operation takes place through control line 50. Controller 100 is configured to control the half phase modules of the rear DC to AC voltage inverters 4546, 47 and 48 to convert the DC voltage on DC bus 33, 34 to AC voltage for supply to electro-mechanical devices 55, 56, 57 and 58 as part of the rear propulsion. Starting propulsion from zero, changing speed to acceleration or deceleration, controller 100 may increase or decrease the voltage and increase or decrease the frequency modulation in selected DC to AC inverters 45, 46, 47 and 48, through lines 50, with which the revolutions—in electro-mechanical devices 55, and 58 or in electro-mechanical devices 56, and 57 or all four electro-mechanical devices together—are boosting or bucking to increase or decrease the speed of the vehicle. DC to AC inverters, and electro-mechanical devices may be different in size and specifications. Nevertheless, controller 100 MO does not change thus, it may be programmed to fit all kind of specifications.
In a regenerative [charge sustaining] mode, controller 100 is configured to control DC to AC voltage inverters 41, 42, 43 and 44 in front of the vehicle through control lines 49 to invert an AC voltage received from its corresponding electro-mechanical devices 51, 52, 53 and 54 into a DC voltage to be supplied to DC bus 31, 32. Similar condition of operation takes place through control line 50 in the rear of the vehicle, which may contain the same configuration as the front of the vehicle.
As part of the operation of controller 100, the controller may receive feedback from plurality of sensors, or transmit control commands to other components within the propulsion and steering operation. In this instance of system 10, controller 100 receives via control line [not shown], specific feedback from voltage sensors 35, 36 coupled in parallel to DC bus 31, 32; and from energy storage unit sensor 30 via control line 18. Controller 100 also receives via control line [not shown], specific feedback from voltage sensors 37, 38 coupled in parallel to DC bus 33, 34; and from energy storage unit sensor 40 via control line 19.
The Ultimate All-Wheel Electronic Steering
The steering portion of system 10 is configured to be incorporated into various embodiment, in miscellaneous types of vehicles, including but not limited to, automobiles, light-duty trucks, delivery trucks, buses, semi-trailers, commercial and industrial vehicles such as mining and construction equipment, marine craft, aircraft, off-road vehicles, material transport vehicles and personal carrier vehicles.
According to the embodiment of the present invention, at some point during vehicle steering—as pre-programmed in the data base—controller 100 may apply various speeds to the left- and/or the right-side wheels; and concomitant, activate all four steering electro-mechanical devices, to position each wheel facing the turning center, which is the central part of this integrated propulsion and steering disclosure, as depicted in
To achieve the precise steering maneuver—which is to steer and propel all 4-wheels at the same time—the following steering steps must be fulfilled:
Steering a vehicle begins when the driver or the AV (AV) ECU elects to change the direction of the vehicle.
If one contact leaflet is defective, broken, disconnected or malfunctioning, controller 100 may be programmed to utilize the last and/or the next leaflet reading—which may be just 1° difference between the leaflets—to keep the wheel within safe range of only 1.66% error; and activate specific warning signal to alert the driver of the malfunctioning leaflet. This fail-assist maneuver complies with NHTSA's “fail operational systems” for steering.
The steering-sensor configuration in
In the embodiment of system 10, steering-sensor 90, comprises of sixty leaflets, thirty for the right turns, and thirty for the left turns. Each leaflet represents a specific angle [in degrees], which is pre-programmed in the data base of controller 100. However, in different configurations, a leaflet may represent any angle; and the number of leaflets on each side of the steering sensor may be elected to fit specific vehicle's applications.
The Integration of the Propulsion with the Steering
The integration of the propulsion into the steering process begins when the driver moves the steering-wheel to a position other than 0°. In AVs, it begins when the ECU initiates a specific turning mode. As a part of system 10, the vehicles schematics in
Gradually turning steering sensor 90 [in
Simultaneously, the front-right wheel speed may be reduced, remain unchanged or increased (see
Simultaneously, the front-left wheel speed—in case where the front-right wheel's speed remains unchanged—will be gradually increased to 43.6 mph to make a perfect turn without a standard EPS (see
Simultaneously, the rear-right wheel speed may be reduced, remain unchanged or increased. It usually matches the front-right wheel's speed (see
Simultaneously, the rear-left wheel speed—in case where the front-right wheel's speed remains unchanged—will be gradually increased to 43.6 mph to match the front-left wheel speed (see
Since at 30° steering the right wheels' turning center has only a radius of about 10′, a 43.6 mph or even 30 mph velocity is not realistic because it may knock the vehicle off balance. While the relationship between speed and turning angle could be empirically determined for each vehicle or calculated by using wheel-base measurements, weight distribution and center of gravity; in the model of 43.6/30 mph turn, the controller is configured to execute control logic stored in a data base associated with the stability of the vehicle. Controller 100 can determine the highest permissible speed at 30° turning mode that will keep the vehicle's velocity below the speed that might endanger the vehicle stability. The program stored in Controller 100 may allow the driver to make the 30° turn safely, yet, only in permissible speed; no matter how hard the driver pushes the accelerator-pedal.
Beside the safety issue, without the ‘overturn prevention system,’ drivers would nervously apply the braking-system, trying to stabilize the vehicle and in the process drive down efficiency. In view of stability benefits—while the propulsion system is involved in the steering process—a vehicle could easily manage lateral acceleration of 0.07 g in 30° turning mode without to apply the braking system. The same applies to AVs because every time brake pads are applied; it cuts down in the vehicle efficiency.
Steering assemblies as depicted in
To push or pull the wheels to the proper angle, system 10 embodiment utilizes ball-screw 112 as a device for converting electro-mechanical rotation of the electro-mechanical device 111 into linear motion of the outer tie rods 113. To minimize friction in ball-screw 112, bearing balls 114 are captured between the nut 118 and the screw-threads. Since controller 100 determines how far the outer tie rod 113 needs to travel to bring the wheel to the desired angle, electro-mechanical device 111 turns the ball-screw 112 and applies axial force through outer tie rod 113 directly to the modified into wheel-position sensor—outer tie rod end 115. Rotor 116 in the electro-mechanical device rotates a shaft that is configured with direct gear 117, or with toothed belt drive wheel [not shown], or with chain drive [not shown] or with any other form of power transmission to nut 118, which rotates and moves ball-screw 112 forward and backwards.
System 10 is configured with four-wheel-position-sensors 115 attached to each wheel's steering knuckle-arm to accomplish the same function as a mechanical tie-rod end, yet, at the same time the sensor monitors, and transmits by electronic means the precise wheel-position to controller 100.
A wheel-position sensor may in fact be configured as a miniature version of steering sensor 90 and may also be constructed that way. Pointer 121 is fixed to the axle of the center-gear 120, which is in tight contact with the teeth of a side-gear 124 and said side-gear teeth are in tight contact with teeth molded inside the wheel-position sensor housing 115. When the nut 118 rotates; the outer tie rod 113 is following the axial movement of screw 112 to the left or the right, triggering a change in the angle between outer tie rod 113 and knuckle steering arm 126, which is proportional to the change in the wheel's angle, i.e. to 0°. The proximate result is rotation of cylinder 125 inside wheel-position sensor's housing 115, triggers the movement of the toothed area 123, molded inside the wheel-position sensor housing, which initiates the following chain reaction: movement of toothed area 123 rotates toothed side-gear 124, which rotates center-gear 120, which causes the movement of pointer 121, that sends by electronic means the ‘change of position’ information to controller 100.
In situations where any of the wheel-position sensors is totally ‘out-of-order,’ controller 100 may be programmed to apply the reading of the opposite side wheel-position sensor to the defective side to keep the vehicle in relatively safe driving conditions and notify the driver by electronic means about the location and the cause of the malfunction. In AVs, a flushing-light and a buzzer will make the passengers aware of the malfunctioning device. This fail-assist maneuver complies with NHTSA's “fail operational systems” for steering.
The myth that mechanical propulsion and steering is safer than electric propulsion and steering is no longer factual. It was vastly demonstrated supra that digital controls can monitor, calculate and actuate EV's aggregates in milliseconds, giving rise to precision in propulsion and steering, which translates also into safety; including but not limited to, electronic malfunction warning systems—as described in the steering section [0110] above-which correct defects by electronic means, and notifying the driver/owner of AV that the vehicle has malfunction that needs repair. Mechanical components brake because of defective materials installed during manufacturing; due to material wear and tear and/or deficient or lack of maintenance results in malfunctions that are not monitored because mechanical propulsion and steering system lack the electronic monitoring systems to inform the driver that the tie rod end is going to brake at the next 90° turn or that speeding at 40 mph in a 90° turn will cause a roll-over.
Integrated Propulsion & Steering for Heavy-Duty Vehicles
Heavy-duty trucks and semi-trailers are widely used for transportation of goods due to their low operation cost; and, since the world population is moving into cities, public transportation is expected to increase dramatically leading to increased number of buses for city and inter-cities transportation. So far, inherent to these class of vehicles, only electrification—in particular with this disclosure—will solve the vehicles' two paramount nuisances and complications they trigger off:
The future semi-trailer's business is projected to be autonomous; well, the only way to bring about autonomous mobility for semi-trailers is propulsion and steering with digitized electronic means while the energy source could be batteries or fuel-cells, both of which provide electric power from different starting points. Traditional diesel engines in buses, heavy-duty and semi-trucks should be abandoned.
Current electric semi-trucks need numerous improvements to be economic viable, and profitable. It is not sufficient to just replace the diesel engine with four electro-motors and propel the same traditional rear-wheels of the tractor; or lower the tractor nose for better coefficient of drag, and continue to steer with the same traditional, mechanical system where only two front-wheels of the tractor are steering a 58′-feet long vehicle. Interpreting system 10 as depict in
Steering an articulated vehicle, with only the front two-wheels is a massive obstacle not only to the semi-driver, but also to all other drivers on the road as presented in
Low-speed multi-wheel vehicle's maneuverability was always a problem in resolving the amount of space required by the vehicle to make a turn as depicted in
When the rear-axles are steered and propelled; this disclosure's design for heavy-duty and articulated vehicles will eventually provide much better result than just improve steering when propulsion is integrated in the steering process:
The design of various electro-mechanical devices may secure that the vehicle never stops because power distribution among about various, and different electro-mechanical devices will eventually eliminate mechanical break-downs because, even though one or several electro-mechanical devices may malfunction, the rest will suffice to keep the vehicle running, which is a top priority, especially in the trucking industry to deliver goods on time. Utilizing induction motors will also eliminate the necessity of water-cooling system and overheating.
The design of the two, relatively large electro-mechanical devices in the rear of the tractor (see
Manufacturing and maintenance cost computations is a very important issues when operating trucking business. Purchase price of a new, standard diesel eighteen-wheeler semi-tractor and trailer is about $170,000 where, standard tractor with diesel engine cost about $130,000; and standard trailer for 18-wheeler, cost about $40,000. Adding steerable rear-wheel system will cost at least additional $20,000; total $190,000. All estimates are on the low-side.
The same new tractor without diesel engine, transmission, drive-shafts and differentials; exhaust system; water-cooling system, pollution prevention system; power-steering system; starting system; alternator charging system; hydraulic-brakes system; and air-conditioning system will cost about $40,000. Then, the trailer $40,000, and a stripped tractor $40,000 will cost together about $80,000.
To manufacture eighteen-wheeler semi-tractor and trailer according to this disclosure, with electric integrated propulsion and steering, may include in general: (i) stripped tractor and trailer $80,000; (ii) 10 propulsion electro-mechanical devices; eight 50 HP induction-motors $960 [@ $120] and two 100 HP induction motors $1,000 [@ $500]; (iii) Adding; 6 dog-clutch mechanisms [4 induction motors, two in the tractor and two in the trailer may be connected to the wheels at all times] $1,800; (iv) six steering electro-mechanical devices $3,000 [@ $500]; (v) 10 DC to DC converters $1,000 [@ $100]; 10 DC to AC inverters $1,000 [@ $100]; (vi) digital system-controller with all wiring at $4,000; (vii) 10 electric-brake systems $2,000 [@ $200] brakes won't be as powerful as in semi-trailers with diesel-engine since regenerative braking by 10 induction motors will do most of the job and evenly distributed along the tractor and trailer; and (viii) air-conditioning system $1,800; total without the battery-pack is about $97,000˜$100,000.
Under previous considerations in ¶ [0026] at 17 supra, the battery-pack weight and cost ¶ [0028] at 18 have a decisive role in designing electric buses, heavy-duty trucks and semi-trailers. Using Tesla semi's specifications, it was computed supra that for 480 Km range the battery-pack will cost $47,000 in today's $100/kWh price, and $23,500 when kWh price will reach $50/kWh in 2024 (see
Maintenance cost of a semi-trailer with this disclosure will be significantly lower than diesel semi-trailer. Average annual distance traveled by Class 8 diesel semi-trucks is about 75,000 miles; and the average efficiency is 6.5 miles per gallon, with yearly consumption of 75,000/6.5=11,540 gallons within a price of $3.90/gal, annual cost of fuel is about $45,000.
Semi-trailer with this disclosure and with the efficiency of 0.75 miles/kWh will consume 100,000 kWh to drive 75,000 miles; with $0.07/kWh commercial price of electricity=$7,000 and with 90% efficiency, annual ‘fuel’ cost=$7,700, which is $37,300 less than semi-truck with diesel engine. 3-years just fuel savings will buy a new electric semi-trailer. The additional expenses with diesel semi-trucks, such as tires replacement, engine lubrication and maintenance, are not available in e-semi-trailers because induction-motors are practically maintenance-free. The battery-pack replacement is only due after about 5-years, depending on the charging methods.
The Modular E-Drive Concept in this Disclosure
The modularity in assembling components of this disclosure is another advantageous aspect that could ease fitting this disclosure in any vehicle type.
Attributable to Modularity of the Design, this disclosure further simplifies, and lowers manufacturing cost.
It should be understood that in certain embodiment electronic controller may include conventional processing apparatus known in the art, and capable of executing pre-programmed instructions stored in associated memory, all performed in accordance with the functionality described herein. To the extent that the methods described herein are embodied in software, the resulting software may be stored in an associated memory where so described, may also constitute the means for performing such methods. Implementation of certain embodiment of the invention, where done so in software, would require no more than routine application of programming skills by one of ordinary skill in the art, in view of the foregoing enabling description. Such a controller be of the type having both ROM, RAM, a combination of non-volatile memory so that the software can be stored and yet allow storage and processing of dynamically produced data and/or signal
