20-04-2010, 05:15 PM
[attachment=3260]
BOSE ELECTROMAGNETIC SUSPENSION
Abstract:
Now a dayâ„¢s comfort and control are two major aspects in field of design and manufacturing. At present condition spring and damper system are used as shock absorber in automobiles. As concerned to comport and control their system are lagging to provide optimum level of performance. With view of increase the comfort and control electromagnetic suspension system introduced to fulfill the requirement of modern days. This seminar intended to explain the resurgence of interest in the suspension system in recent year and outline the significant challenges that lie a head in commercializing suspension system.
Introduction:
Bose, mention that word and music comes to mind specifically, audio systems for upscale cars, as well as expensive but worth-the-cost systems for the home. Business travelers might even connect that name with noise-canceling headphones that reduce some of the stress of flying. What one doesn't associate with Bose is automobile suspension. By and large, todayâ„¢s vehicle suspensions use hydraulic dampers (shock absorbers) and springs that are charged with the tasks of absorbing bumps, minimizing the car's body motions while accelerating, braking and turning and keeping the tires in contact with the road surface. Typically, these goals are somewhat at odds with each other. Luxury cars are great at swallowing bumps and providing a plush ride, but handling usually suffers as the car is prone to pitch and dive under acceleration and braking, as well as body lean under cornering .On the other end of the spectrum, stiffly sprung sports cars exhibit minimal body motion as the car is driven aggressively, as cornering is flat, but the ride quality generally suffers. In an ongoing research project that has spanned over 24 years Bose has created a unique electromagnetic suspension system for automobiles that is close to commercial release and is set to replace traditional shocks and springs with electronic actuators. "This is the first time a suspension system is the same for a sports car and for a luxury car", said its creator, Dr Amar Bose, chairman and head of technical design. The result is a ride that is level and bump free over incredibly rough terrain and when the vehicle turns in to corners.
Suspension:
The main objectives of the suspension system are:
¢ To prevent the road shocks from being transmitted to the vehicle parts, thereby providing suitable riding and cushioning effect to the occupants.
¢ To keep the vehicle stable while in motion by providing good road holding during driving cornering and braking.
¢ Provides safe vehicle control and free of irritating vibrations and reduce wear and tear.
The different types of suspension system which are available are mentioned below.
1. Front Suspension:
Solid I-Beam:
Itâ„¢s a Non-independent design .These is used on trucks and other large vehicles. Its economical and simple .It has low maintenance but poor handling.
Twin I-Beam:
Found on many Ford trucks. Its Forged, cast, or stamped axles. Has excellent load capacity. It requires special equipment for alignment adjustments.
Mac Pherson Strut:
One of the most popular systems .It has one Control Arm. Ideal for front wheel drive. Light weight and economical. Good ride quality and handling characteristics. Itâ„¢s used for both front and rear suspensions.
Short-Long Arm:
Independent design uses an upper and a lower control arm uses either torsion bars or coil springs Good ride quality and handling characteristics Heavy and complex design requires a lot of space.
2. Rear Suspension:
Non Independent Rear Leaf Springs:
Itâ„¢s a non-independent design Similar to front solid I-beam axle. Used for large load carrying capacity.
Non Independent Rear Coil Springs:
Itâ„¢s a non-independent design .Uses coils and control arms instead of leaf springs. Has good load carrying capacity.
Trailing Arm:
Itâ„¢s an Independent Design Uses individual lower control arms. Uses coil springs and shocks for good ride quality.
Beam:
Non-independent design Stamped beam axles. Uses coil springs and trailing arms. Used for light and simple design.
Challenges:
Every automotive suspension has two goals: passenger comfort and vehicle control. Isolating the vehicleâ„¢s passengers from road disturbances like bumps or potholes provides comfort. Control is achieved by keeping the car body from rolling and pitching excessively, and maintaining good contact between the tire and the road.
Unfortunately, these goals are in conflict. In a luxury sedan the suspension is usually designed with an emphasis on comfort, but the result is a vehicle that rolls and pitches while driving and during turning and braking. In sports cars, where the emphasis is on control, the suspension is designed to reduce roll and pitch, but comfort is sacrificed. Bose engineers took a unique approach to solving this problem, and the result is an entirely new approach to suspension design.
Solution:
In 1980, Bose founder and CEO Dr. Amar Bose conducted a mathematical study to determine the optimum possible performance of an automotive suspension, ignoring the limitations of any existing suspension hardware. The result of this 5-year study indicated that it was possible to achieve performance that was a large step above anything available. After evaluating conventional and variable spring/damper systems as well as hydraulic approaches, it was determined that none had the combination of speed, strength, and efficiency that is necessary to provide the desired results. The study led to electromagnetics as the one approach that could realize the desired suspension characteristics.
The Bose suspension required significant advancements in four key disciplines: linear electromagnetic motors, power amplifiers, control algorithms, and computation speed. Bose took on the challenge of the first three disciplines and bet on developments that industry would make on the fourth item. The above figure shows the front module of a BOSE suspension. Prototypes of the Bose suspension have been installed in standard production vehicles. These research vehicles have been tested on a wide variety of roads, on tracks, and on durability courses.
Working:
The Bose system uses a linear electromagnetic motor (L.E.M.) at each wheel, in lieu of a conventional shock and spring setup. The L.E.M. has the ability to extend (as if into a pothole) and retract (as if over a bump) with much greater speed than a fluid damper (taking just milliseconds). These lightning-fast reflexes and precise movement allow the wheel's motion to be so finely controlled that the body of the car remains level, regardless of the goings-on at the wheel level.
The L.E.M. can also counteract the body motion of a car while accelerating, braking and cornering, giving the driver a greater sense of control and passengers less of a need for Dramamine. To further the smooth ride goal, wheel dampers inside each wheel hub smooth out small road imperfections, isolating even those nuances from the passenger compartment. Torsion bars take care of supporting the vehicle, allowing the Bose system to concentrate on optimizing handling and ride dynamics.
A power amplifier supplies the juice to the L.E.M.s. The amplifier is a regenerative design that uses the compression force to send power back through the amplifier. Thanks to this efficient layout, the Bose suspension uses only about a third of the power of a vehicleâ„¢s air conditioning system. There are a few other key components in the system, such as control algorithms that Bose and his fellow brainiacs developed over a few decades of crunching numbers. The target total weight for the system is 200 pounds, a goal Bose is confident of attaining.
Bose suspension front corner module
The Bose suspension system installs easily into the front of the vehicle. A new engine cradle connects the front suspension to the car body using the original factory mounting hardware, creating a drop-in replacement module. Bose's front suspension modules use a modified MacPherson strut layout and the rear suspension modules use a double-wishbone linkage to attach a linear electromagnetic motor between the vehicle body and each wheel. Torsion springs are used to support the weight of the vehicle. In addition, the Bose suspension includes a wheel damper at each wheel to keep the tire from bouncing as it rolls down the road. Unlike conventional dampers, which transmit vibrations to the vehicle occupants and sacrifice comfort, the wheel damper in the Bose system operates without pushing against the car body, maintaining passenger comfort.
Linear Electromagnetic Motor:
A linear electromagnetic motor is installed at each wheel of a Bose equipped vehicle. Inside the linear electromagnetic motor are magnets and coils of wire. When electrical power is applied to the coils, the motor retracts and extends, creating motion between the wheel and car body. One of the key advantages of an electromagnetic approach is speed.
The linear electromagnetic motor responds quickly enough to counter the effects of bumps and potholes, maintaining a comfortable ride. Additionally, the motor has been designed for maximum strength in a small package, allowing it to put out enough force to prevent the car from rolling and pitching during aggressive driving maneuvers. The Bose linear electromagnetic motor offers easy two-point mounting. The only electrical connections to the motor are for power and control.
Linear motor:
Linear motor is essentially a multi-phase alternating current (AC) electric motor that has had its stator "unrolled" so that instead of producing a torque (rotation) it produces a linear force along its length. The most common mode of operation is as a Lorentz-type actuator, in which the applied force is linearly proportional to the current and the magnetic field (F = qv × B). Many designs have been put forward for linear motors, falling into two major categories, low-acceleration and high-acceleration linear motors. Low-acceleration linear motors are suitable for maglev trains and other ground-based transportation applications. High-acceleration linear motors are normally quite short, and are designed to accelerate an object up to a very high speed and then release the object, like roller coasters. They are usually used for studies of hypervelocity collisions, as weapons, or as mass drivers for spacecraft propulsion. The high-acceleration motors are usually of the linear induction design (LIM) with an active three-phase winding on one side of the air-gap and a passive conductor plate on the other side. The low-acceleration, high speed and high power motors are usually of the linear synchronous design (LSM), with an active winding on one side of the air-gap and an array of alternate-pole magnets on the other side. These magnets can be permanent magnets or energized magnets. The Transrapid Shanghai motor is an LSM.
Research Vehicle:
In many of todayâ„¢s production vehicles, the suspension system is comprised of front and rear suspension modules that bolt to the underside of the vehicle. The Bose suspension takes advantage of this configuration by creating replacement front and rear suspension modules. Using this approach, the research team has been able to retrofit the Bose suspension into existing production vehicles with minimal modifications. Boseâ„¢s front suspension modules use a modified McPherson strut layout and the rear suspension modules use a double-wishbone linkage to attach a linear electromagnetic motor between the vehicle body and each wheel. Torsion springs are used to support the weight of the vehicle. In addition, the Bose suspension includes a wheel damper at each wheel to keep the tire from bouncing as it rolls down the road. Unlike conventional dampers, which transmit vibrations to the vehicle occupants and sacrifice comfort, the wheel damper in the Bose suspension system operates without pushing against the car body, maintaining passenger comfort.
Comparison of Factory Installed & BOSE Suspension System
On A Bumpy Surface
Two vehicles of the same make and model are driven over a bump course at night. The vehicle on the top has the original factory installed suspension and the vehicle on the bottom has a BOSE suspension system. Both vehicles are being driven at the same speed. The lexus with the standard factory installed suspension (below).
A Lexus with a standard suspension
Joggles as it coasts along a bumpy surface, while another Lexus with the BOSE suspension system (below) sails along the same road unperturbed.
A Lexus with the Bose system
Body Roll While Cornering:
Two vehicles of the same make and model are shown performing an aggressive cornering maneuver.
A Lexus with a standard suspension
A Lexus with the BOSE suspension
In the photo, the Lexus car without the BOSE system leans as it turns a corner, while the car with the Bose system remains stable.
Body Pitch on braking & accelerating:
The front end of the car dips when the driver of a Lexus fitted with the standard factory fitted suspension system slams brakes. In a Lexus with the BOSE suspension system; drivers quickly notice the elimination of body pitch during hard braking and acceleration. Professional test drivers have reported an increased sense of control and confidence resulting from these behaviors.
Vehicle Performance:
Vehicles equipped with the Bose suspension have been tested on a variety of roads and under many different conditions, demonstrating the comfort and control benefits drivers will encounter during day to-day driving. In addition, the vehicles have undergone handling and durability testing at independent proving grounds. When test drivers execute aggressive cornering maneuvers like a lane change, the elimination of body roll is appreciated immediately. Similarly, drivers quickly notice the elimination of body pitch during hard braking and acceleration. Professional test drivers have reported an increased sense of control and confidence resulting from these behaviors. When test drivers take the Boss suspension over bumpy roads, they report that the reduction in overall body motion and jarring vibrations results in increased comfort and control.
Features:
The system draws about two horsepower or one-third the load of a typical air conditioner. While it can exert 50 kilowatts (67 horsepower) of energy to leap a 2x6(plank) covers 49 kilowatts cushioning the landing, with the shocks working like generators.
Torsion bars and shock units weigh about what two conventional springs and shocks. The controllers and upsized alternator also add some weight, but the total should be less than that of a hydraulic active suspension.
The system lets a vehicle ride lower at highway speeds to produce less drag and improve handling
To save power the system is regenerative. When the far side of a pothole helps to push the wheel up almost all the power is recovered. The motors momentarily become generators, shunting the recovered energy to storage, either in the engine battery or in some other device. The system ends up consuming one-third of the energy used by a cars air-conditioner.
Disadvantages:
Every system has some disadvantages attached to it.Some of the drawbacks can be grouped as below
The main drawback of the system is the cost.As it uses nyodinium magnets which are costly to manufacture.Thus this makes this suspension system costlier than any other suspension available.Thus this system can be seen in only high end cars
The second drawback is ,when this system breakdowns its very difficult and costly affair to repair it .The other system available can be easily be repaired
The system is very complex and requires high precision machinery and skilled workers to manufacture
Future Prospects:
Dr. Bose stated that within five years the company hopes to have the Bose suspension offered on one or more high-end luxury cars, and thanks to the system's modular design, it shouldn't be much of a problem to install at the factory. A manufacturer will be chosen to co-develop a production application for sale after three or four years. GM is expected to be the first development partner, given the long relationship between the companies. The biggest setback would be the cost as it is going to cost more than any suspension does now. The neodymium iron in the magnets is the most expensive part. Expect to see electromagnetic suspensions only on very expensive cars first, and probably never on cheap ones, though we imagine that the cost would come down as production goes up.
Conclusion:
For the first time, the Bose suspension demonstrates the ability to combine in one automobile a much smoother ride than any luxury sedan, and less roll and pitch than any sports car. This performance results from a proprietary combination of suspension hardware and control algorithms
References:
¢ Electromagnetic Suspension Systems, http://boselearning/project_sound/bose_suspension.jsp.
¢ Bose Redefines Automobile Suspension System, http http://gizmaggo/3259/
¢ Electronic Suspension http://auto.howstuffworkscar-suspension9.htm.
¢ Future of Car Suspensions, http://wikipedia.com.
INDEX:
1. Abstract¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦..5
2. Introduction¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦6
3. Suspension¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦......7
4. Challenges¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦......8
5. Solution¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦......9
6. Working¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦. ..10
7. Bose suspension front corner module¦¦¦¦¦¦¦¦¦¦¦¦......11
8. Linear electromagnetic motor¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦..12
9. Linear motor¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦.13
10. Research vehicle¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦.. 14
11. Comparison of factory installed and Bose suspension system¦¦¦¦.14
12. Body pitch on braking and accelerating¦¦¦¦¦¦¦¦¦¦¦¦...15
13. Vehicle performance¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦....16
14. Features ¦¦¦¦¦¦¦. .¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦... 16
15. Disadvantages¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦..17
16. Future prospects¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦...17
17. Conclusion¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦...17
18. Reference¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦.18
????
