Fluid-pressure and analogous brake systems – Speed-controlled – Regenerative brakes
Reexamination Certificate
2001-12-20
2004-03-09
Schwartz, Christopher P. (Department: 3683)
Fluid-pressure and analogous brake systems
Speed-controlled
Regenerative brakes
C180S065310, C188S162000
Reexamination Certificate
active
06702404
ABSTRACT:
BACKGROUND OF THE INVENTION
Control of power transmission and torque is a frequent problem in many fields of application. In automobiles and trucks, clutches and brakes are used to transmit torque, or to accelerate or decelerate a vehicle. Normal wear on the friction components of these systems results in periodic and expensive repairs in countless applications not only in the United States, but worldwide wherever such systems are used.
Friction systems for deceleration typically used are one of two types: drum systems with traditional wear pads, or disc systems with a friction rotor/stator arrangement. Both types have wear components that must periodically be checked and replaced. Failure to check and repair or replace worn components can result in damage to the actuation system, such as warped rotors or wearing by application calipers directly on drums or other components. Such systems are also typically equipped with hydraulic systems for easier application and control. While the hydraulic systems make application easier, hydraulics do nothing to ease the wear situation and may indeed aggravate the wear on these systems by more aggressive application and use. The net result of these systems is to convert kinetic energy from wheels and axles into heat in the brake pads or discs, which then suffer further wear.
As a result of the deficiencies of these systems, electromagnetic retarders have been used for braking and deceleration systems. The concept behind electromagnetic retardation is to use an electric motor as an eddy current machine, that is, to retard the rotation of a rotor by applying a reluctance on a matching stator. The energy so used may recharge a battery (as in a regenerative braking system) or may be dissipated as heat if the application requires converting a large amount of kinetic energy (torque) to electrical energy or heat. Such a system may not always convert braking energy to another useful form of energy, but it may work for its intended primary purpose: stopping motion of a car, a truck or other moving or rotating body.
Present systems using electromagnetic retarders do not consider the effect of braking on the entire vehicle or body, but tend to consider only an individual wheel or other moving unit. For example, U.S. Pat. No. 5,743,599 reveals an electromagnetic retarding system for a vehicle in which there is an electromagnetic retarder for each wheel, but no consideration of the overall effect on the entire vehicle. Such a system may work for each wheel individually, but provides no balancing mechanism for the automobile or car employing the electromagnetic retarding system. For instance, electromagnetic retarders lose their effectiveness at low speeds, since little torque is available for conversion at low speeds. In some instances, torque may be available at one wheel or moving portion but not at another wheel or another portion of the vehicle employing the retarding system. As a result, the electromagnetic actuation system may not have the ability to control those retarders at which energy or torque is not otherwise available. What is needed is a way to balance the energy-conversion or torque-conversion needs of the entire vehicle or device using an electromagnetic retarding system. What is needed is a better way to control an electromagnetic retarding system to decelerate a vehicle or other moving object.
BRIEF SUMMARY OF THE INVENTION
The present invention meets this need with an electromagnetic retarding system. One aspect of the invention is an electromagnetic retarding system comprising a plurality of electromagnetic retarders, each retarder operably connected to a rotating shaft. The electromagnetic retarding system also comprises a sensor for measuring at least one of a speed and a torque of the shaft. There is a brake controller receiving inputs from the sensors, the controller controllably connected to each of the plurality of magnetic retarders, and means for supplying power to each of the electromagnetic retarders, the means controllably connected to the controller. In this aspect, the controller routes power to each of the plurality of electromagnetic retarders to oppose the rotating shafts connected to each retarder, and the power routed to each retarder depends on an error signal between an actual and a desired amount of at least one of a speed and a torque set by the controller for each of the plurality of retarders.
Another aspect of the invention is an electromagnetic retarding system for a motor vehicle. The electromagnetic retarding system comprises an electromagnetic retarder operatively coupled to each axle of the motor vehicle, and a sensor operably connected to each axle to indicate at least one of an axle speed and an axle torque. There is a power source or sources providing power for the electromagnetic retarders, and at least one sensor operably connected to a brake pedal of the vehicle for indicating at least one of a brake pedal displacement and a brake pedal force. The electromagnetic retarding system also comprises a controller in operable communication with the electromagnetic retarders, the sensors, and the power source or sources. In this electromagnetic retarding system for a motor vehicle, the controller applies power from the power source or sources to the electromagnetic retarders to decelerate the vehicle. The controller controls the application of the power by using at least one of a wheel speed, an axle torque, a brake pedal displacement, a brake pedal force, and a temperature.
Another aspect of the invention is a method for decelerating a moving object having at least two rotating shafts. The method comprises providing an electromagnetic retarding system for each rotating shaft. The method also comprises indicating for each shaft at least one of an actual deceleration, a desired deceleration, an actual torque and a desired torque, and then calculating a retarding force for each shaft. The method then applies an electromagnetic retarding force to each shaft, wherein the force applied to each shaft is dependent on at least one of a difference between the actual and the desired deceleration, and the actual and the desired torque of the shaft.
Yet another aspect of the invention is a method of braking a motor vehicle. The method provides an electromagnetic retarding system for providing a braking force to each axle of the motor vehicle. The method then indicates an actual parameter and a desired parameter for each axle, the parameter selected from the group consisting of torque and deceleration. For vehicles having dual wheels/tires, a single indicator for a pair or for four wheels on a shaft or an axle is sufficient. The method then calculates a braking force for each wheel or axle of the vehicle, and then applies the braking force to each axle of the vehicle via one or more electromagnetic retarders. The force applied to each axle is dependent on the difference between the actual and the desired parameter. The applied torque is also a function of the power available from the power source.
There are many aspects and embodiments of the invention, many of which will become clearer from the accompanying drawings and descriptions.
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Anwar Sohel
Pavlov Kevin J.
Brinks Hofer Gilson & Lione
Schwartz Christopher P.
Visteon Global Technologies Inc.
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