Conveyors: power-driven – Conveyor section – Live roll
Reexamination Certificate
1999-04-19
2001-03-27
Ellis, Christopher P. (Department: 3652)
Conveyors: power-driven
Conveyor section
Live roll
C198S784000
Reexamination Certificate
active
06206181
ABSTRACT:
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT
BACKGROUND OF THE INVENTION
The present invention relates to roller conveyors and motorized rollers used to move packages along roller conveyors.
Roller conveyors are used to move packages, trays, or containers where accumulation of individual containers is required. Roller conveyors may be advantageously used when items are accumulated from a number of locations and dispatched to multiple destinations, for example in moving sorted mail contained in trays from sorting locations to a loading dock where mail destined for a particular vehicle or container is accumulated. Roller conveyors consist of a roller tube which is mounted for rotation about the cylindrical axis of the roller. The rollers are spaced on the conveyors so that the minimum sized package is supported by at least three rollers at all times. Drive rollers are positioned between idler rollers and used to move and stop packages on the conveyor. The spacing and number of drive rollers relative to idler rollers depends on the size of the packages anticipated and the torque or drive force which is required. Groups of drive rollers may be used if greater drive forced is required.
Although drive rollers may be driven by belts from external motors, the typical modem approach is to use rollers with internal electric motors which are mounted to a fixed shaft and drive the roller through a gear system. The use of internal-motor-driven rolls simplifies the assembly of the roll conveyor and eliminates a large number of pulleys and external motors which occupy space and require guards to protect workers.
Roller conveyors can be used to precisely control the motion of many packages with each motor under the control of a central computer or programmable controller.
By controlling the individual drive motors, a package can be moved forward or can be brought to a stop by using the drive rollers as a brake. The rollers can operate individually or as an integrated system to accumulate packages with zero pressure, and release packages in a slug release or singulation mode. A roller conveyor can be used to combine streams of packages onto a single conveyor going to a single or multiple destinations. Packages on a first conveyor line which intersects a second conveyor line can be held and injected one by one as space becomes available on the second conveyor. Thus the conveyors will typically be used with multiple sensors which sense the passage of discrete packages, and a controller which is designed and programmed for a particular application.
Standard rollers of both the drive and idler types are 1.9 inches in diameter. The drive rollers are typically supplied as a sealed unit and utilize small high speed brush motors. The roller sealed units are typically disposed of when the brushes wear out. The typical life of a drive roller and motor unit is less than 2,000 hours. A typical drive roller costs $90.00 and has a service life of less than one year. Although units using brushless D.C. motors are known, the life of the units is still limited by the life of the gears which drive the roller tube.
Cost is a very important consideration in the design of drive rollers for roller conveyors. A typical installation may contain hundreds to thousands of feet of conveyor and, with one drive roller spaced every two to three feet, the number of drive rollers which must be purchased yearly to maintain such a system can be a considerable expense.
What is needed is a drive roller with a longer life and a lower cost.
SUMMARY OF THE INVENTION
The drive roller of this invention utilizes a brushless D.C. motor which has a stator or armature mounted on a fixed shaft which directly drives a permanent magnet rotor mounted inside a roller tube. A variable frequency drive supplies three-phase 24-volt power to a Y-connected three phase winding which is composed of three groups of four coils. Thus twelve electromagnets are formed. The electromagnets are used to drive the permanent magnet rotor which has sixteen poles. The brushless D.C. motor is of a modular design and can be easily built in two inch length increments to supply 2 lb-in of torque for each two-inch increment. The variable frequency controller operates at a relatively low frequency of 15-75 Hz. Because of the low drive frequency, hysteresis losses in the armature laminations are extremely low and ordinary mild steel can be used to form them. The armature laminations making up the brushless D.C. motor core are also relatively thick because of the relatively low frequency power necessary to drive the motor and the resultant relatively low eddy currents present in the motor core. For a motor with a 4.0 lb-in design torque and a rotor and stator length of four inches, the current draw will be approximately 1.5 amps at rated torque consuming about 35 watts of power. The motor will drive the roller at approximately 265 rpm which corresponds to a conveyor speed of approximately two feet per second or 120 feet per minute.
Because the only moving parts of the drive roller are the bearings, which have a life of approximately 100,000 hours, the overall life of the drive unit is expected to be considerably more then ten times that of conventional units. In addition, the cost of the units is expected to be less than existing units because of the elimination of gears and brushes. The motor itself utilizes low-cost ferrite magnets in the rotor and low-cost armature cores utilizing mild steel and relatively few laminations. Further, the construction of the motor is simplified because the windings are inserted into the core from the outside of the core and thus are cost-effectively manufactured.
It is an object of the present invention to provide a drive roller for a roller conveyor which has a longer operational life.
It is a further object of the present invention to provide a drive roller for a roller conveyor which is designed for cost-effective production.
It is another object of the present invention to provide a drive roller in which the drive speed can be precisely controlled.
It is also an object of the present invention to provide a drive roller for a roller conveyor which can be used to position articles on a roller conveyor.
Further objects, features and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 1448712 (1923-03-01), Pool
patent: 1743223 (1930-01-01), Lowy
patent: 1825119 (1931-09-01), Mug
patent: 1889173 (1932-11-01), Drexler
patent: 2013858 (1935-09-01), Lawlor
patent: 2175860 (1939-10-01), Walmann
patent: 2915167 (1959-12-01), Berger
patent: 4047609 (1977-09-01), Nazuka
patent: 4082180 (1978-04-01), Chung
patent: 4998052 (1991-03-01), Erdman et al.
patent: 5022513 (1991-06-01), Huber
patent: 5025915 (1991-06-01), Huber
patent: 5030864 (1991-07-01), Van Hout et al.
patent: 5033611 (1991-07-01), Huber
patent: 5088596 (1992-02-01), Agnoff
patent: 5127513 (1992-07-01), Huber
patent: 5131527 (1992-07-01), Huber
patent: 5180344 (1993-01-01), Hall
patent: 5336956 (1994-08-01), Haner
patent: 5413209 (1995-05-01), Werner
patent: 5462156 (1995-10-01), Kobayashi et al.
patent: 5548173 (1996-08-01), Stephenson
patent: 5923111 (1999-07-01), Eno et al.
patent: 5927477 (1999-07-01), Meitunnen
patent: 518773 (1931-02-01), None
patent: 2616418 A1 (1987-06-01), None
patent: 54-159982 (1979-12-01), None
patent: 3-98905 (1991-04-01), None
patent: 1486199 (1989-06-01), None
“Kane Magnetics Materials” Advertizing document, p. 3,1998.*
“ITOH Power Moller® J-Series,” Somfy Systems, Inc., Cranbury, NJ, 4 pages.
“ITOH Power Moller® S-Series,” Somfy Systems, Inc., Cranbury, NJ, 4 pages.
“Power Moller®,” Somfy Systems, Inc., Cranbury, NJ Aug. 16, 1993, 7 pages.
“Motorola Brushless DC Motor Controller”, Motorola, Inc., 1998
Deuble Mark A.
Ellis Christopher P.
Lathrop & Clark LLP
Motion Systems, L.C.
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