Brakes – Internal-resistance motion retarder – Using magnetic flux
Reexamination Certificate
2003-04-03
2004-11-23
Siconolei, Robert A. (Department: 3683)
Brakes
Internal-resistance motion retarder
Using magnetic flux
C188S161000, C310S093000, C310S105000
Reexamination Certificate
active
06820728
ABSTRACT:
TECHNICAL FIELD
The invention relates to an electrical system for road vehicles and the relationship between the vehicle's electrical system and drive-train for controlling torque, power generation, and engine start-up; specifically where a permanent magnet generator is coupled to a secondary shaft.
BACKGROUND ART
Commercial vehicles such as semi-trucks, garbage haulers, buses and the like, often incorporate a retarder as a way to reduce the vehicle's velocity without having to utilize friction brakes every time the vehicle is required to slow. Use of a retarder would therefore be a way to extend the useful life of a vehicle's brakes and avoid frequent and costly brake maintenance.
The power supply for these retarder devices can come from several sources. Some retarders operate by controlling the intake and exhaust valves of an engine; some by restricting engine exhaust; while other retarders are designed to utilize hydraulic power, magnetic or electromagnetic interaction. All retarders function to absorb or dissipate the kinetic energy associated with a moving vehicle.
In this specification, retardation is defined as the use of an electromagnetic retarder to slow a vehicle.
For electromagnetic retarders, two methods are known in the prior art for exciting its magnetic field:
One method uses the vehicle's battery and alternator, as a power source. As illustrated in.
FIG. 2
, retarder
30
competes with the rest of the vehicle loads for available power. During retardation, which occurs for example when traveling downhill, the engine is operating at a lower RPM. For this situation, the output of alternator
22
is insufficient to maintain the battery fully-charged. Also, retardation causes depletion of the battery charge.
The second method uses permanent magnets instead of a field winding. In this configuration, there is no demand placed upon the vehicle battery and alternator for retardation. However, the torque produced by retardation is limited primarily to either a full ON or full OFF condition. Alternatively, a costly rotor displacement can be incorporated, which would provide the ability to vary the retardation torque.
Besides electromagnetic retardation, it is well known in the prior art to employ hydraulic retardation as a means for assisting vehicular braking.
Disclosure of Invention
The invention is best described as an electromagnetic retarder system for use with motorized vehicles. Additional functions can comprise the retarder system, which can be adapted to include one or a combination of the following: 1) a brushless DC alternator; 2) a brushless DC starter; 3) a passive/active damper that replaces the vehicle's flywheel; 4) a transmission-synchronizing inertia brake; and, 5) a booster to offset the lag associated with using a turbocharger. A retarder system incorporating one or more of these functions can be collectively referred to as an Integrated Retarder And Accessory Device package (IRAAD). The IRAAD is explained below and has also been described in U.S. Pat. No. 6,543,588.
The purpose of this application is to introduce two improvements that may be incorporated as part of an IRAAD The first improvement is directed to a combination hydraulic-electromagnetic retarder and the second is directed to the use of a PMG in cooperation with a gear-box running off of the drive-train.
Original IRAAD Disclosure
The housing which contains the retarder system may be integrated with the engine or with the transmission. While the engine is operating, it produces torque on the drive shaft for powering the transmission. When required, the retarder produces retardation torque, or negative torque, to reduce the velocity of a vehicle.
The retarder system can be positioned either at the input or the output of the transmission. Positioning is determined by the desired application, as each location has its own advantages.
For example, a retarder system placed at the output of a transmission can be made small and lightweight by providing it with a high speed shaft. However, at this position, the retarder system could not be an effective starter or generator because it rotates only when the transmission is engaged by the clutch or other torque link.
Conversely, a retarder system located at the input of a transmission, while large, may take advantage of gear ratios obtained from downshifting, to produce an even greater torque. Also, when the retarder rotor assembly, which will be discussed in detail below, is positioned between the engine and transmission, its function as a generator is unimpaired, as rotation occurs as long as the engine is running. Finally, because the rotor assembly of the retarder system is coupled directly to the crankshaft, the device can be used as a starter. For these stated reasons, the retarder system is preferably positioned between engine and transmission. Also, for this configuration, it is preferred that the induction ring, sometimes referred to as the retarder drum, be adapted for a coolant to pass through so that it can be connected to the vehicle's existing cooling system (i.e. radiator) for dissipating the heat generated during retardation.
The invention comprises an electromagnetic retarder connected along the drive-shaft to an exciter generator. A permanent magnet generator (PMG) is drivingly coupled to the drive shaft. It can be located about the drive shaft but it is not directly connected to either the retarder or exciter generator in the physical sense although output from the PMG will be used for the exciter generator. At least one rectifier is positioned between and hard-wired to the field winding and exciter rotor. In the preferred embodiment, the field winding, the rectifier and the rotors of the exciter and PMG are collectively referred to as the retarder rotor assembly.
Positioned about the rotor assembly is a housing which can be integrated with either the engine or transmission housing, or as a separate housing. This housing preferably comprises the induction ring, and the stators of the exciter generator and PMG. Therefore, the retarder, exciter generator and PMG each have relatively rotatable elements, the stationary retarder induction ring and stators of the exciter generator and PMG, and their respective rotatable elements, the field winding and exciter rotor and PM rotor which rotate when the drive train is operable.
The exciter generator allows for brushless operation, while the PMG is referred to as “self-excited” because its rotor is coupled to the vehicle's drive-shaft and will produce current so long as the drive-shaft is rotating.
The electromagnetic retarder operates by energization of the rotating field winding of the rotor assembly to interact with a stationary induction ring to produce torque, which, together with drive-shaft rotation, generates power. Therefore, both of the retarder elements, the field winding and the induction ring are in surrounding relation to the main drive shaft.
It is important to note that, although torque may exist between the field winding of the rotor assembly and the induction ring even at a standstill due to magnetic attraction, for torque to be produced according to the invention, there must exist relative motion between the PMG rotor and stator. In other words, the field winding requires energization by an electric current which is created as a result of the output produced by the PMG.
This allows the PMG to convert mechanical power to the electrical energy required to energize the exciter generator and ultimately the field winding of the rotor assembly. Since the PMG will produce electricity whenever the drive-shaft is rotating, it is necessary to use a regulator to regulate the level of current reaching the exciter stator. Operation of the regulator would depend upon the type of external signal received. In addition, a power conditioning unit (PCU) is required to condition the alternating current (AC) produced by the PMG into direct current (DC).
The invention will operate equally as well if the induction ring is made to rotate, and the magnetic field
Chabot Ralph D.
Kramer Devon
Pacific Scientific Electrokinetics Division
Siconolei Robert A.
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