Electricity: motive power systems – Braking – Dynamic braking
Reexamination Certificate
1999-08-12
2001-05-15
Nappi, Robert E. (Department: 2837)
Electricity: motive power systems
Braking
Dynamic braking
C318S376000, C318S471000, C388S934000
Reexamination Certificate
active
06232732
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of and circuit for braking an electric drive motor and, more particularly, to a method and circuit for braking a drive motor for driving a grooved drum of a winding head in a bobbin winding machine wherein the motor is braked in a direction opposite to a rated nominal current by loading the motor with a braking current whose strength can be a multiple of the rated current.
In many applications of electric drive motors, attempts are made to brake the motors to a standstill as rapidly as possible. In the case of bobbin winding machines, e.g., in which an electric drive motor drives a grooved drum of a winding head, attempts are made to brake the drive motors as rapidly as possible as required in order to keep the standstill times of the winding heads short and thereby to keep the efficiency of the bobbin winding machine high. Spinning cops are rewound at the winding heads to large-volume cross-wound bobbins. The yarn are monitored during the rewinding for yarn errors. If a yarn error is determined, the rewinding process is interrupted, the yarn piece with the error is cut out, a yarn connection is established between the remaining yarn pieces, and the winding process is restarted. In order to carry this out in as short a time as possible, it is also necessary to bring the grooved drum to a standstill as rapidly as possible.
In order to brake an electric drive motor electrically, it is loaded with a brake current in a direction opposite to the rated current of the motor. The braking time is thereby a function of the magnitude of the braking current, which can be a multiple of the rated current without any concern for damage to the drive motor in the normal instance. Usually, a thermal monitoring device is provided for such drive motors which determines a thermal overload and then interrupts the operation of the drive motor and thereby prevents severe motor damage from occurring as a consequence of overheating of the motor. Such a thermal overloading can occur if a drive motor of a grooved drum is repetitively braked and re-accelerated for short periods of time in succession. The drive motor is then deenergized by the temperature monitoring device and remains deenergized until the temperature has dropped back below the set safety value. As a rule, a red light is also placed at the winding head concerned, which indicates that there is a problem at this winding head which requires an intervention of the operating personnel. This results in standstill times and, in turn, in not insignificant losses of output efficiency of the device or machine involved.
SUMMARY OF THE INVENTION
The present invention thus has the object of creating a braking method and a braking circuit of the initially described type in which an element driven by the drive motor or the associated machine can operate with the greatest efficiency possible.
This object is basically achieved by a braking method and circuit in which the instantaneous thermal load of the drive motor is constantly detected and the strength of the braking current is selected as a function of this thermal load of the drive motor.
Thus, upon each initiation of a braking process, the highest possible strength of the braking current suitable for the braking process is determined so that, even in the case of several braking processes repeated at short intervals in succession, the work can be performed with a maximum braking force which minimizes the braking time without any overloading of the drive motor occurring. Different braking times accordingly result as a function of the instantaneous thermal loading of the drive motor, that is, relatively higher braking times occur upon a relatively higher thermal load without, however, the drive motor entering into a temperature range requiring the motor to be deenergized.
In order to keep the equipment expense as low as possible, one aspect of the invention provides that the instantaneous thermal loading of the drive motor is detected from the loading of the drive motor with current over time. In this manner, the expense for measuring technology or equipment can be kept relatively low.
A further development of the invention provides that graduated values are set for braking currents which are associated with an area of thermal loading. Such a stepped fixing of the suitable braking current is quite sufficient for a practical realization of the invention objectives.
The braking circuit of the invention basically provides means for detecting the instantaneous thermal load of the drive motor and means for selecting the braking current to be applied for a braking process as a function of this thermal load.
According to a further aspect of the invention, the braking circuit provides means for assigning the detected thermal load to values of thermal loads stored in a memory and means for activating a braking current with a strength set for the assigned thermal load value.
Further features and advantages of the invention are explained in the following description of exemplary embodiments of the invention shown in the accompanying drawings.
REFERENCES:
patent: 4173732 (1979-11-01), Anderson
patent: 4581565 (1986-04-01), Van Pelt et al.
patent: 4696435 (1987-09-01), Hermanns
patent: 5735473 (1998-04-01), Hermanns et al.
patent: 5778703 (1998-07-01), Imai et al.
patent: 2 106 898 (1972-08-01), None
patent: 38 05 662 A1 (1989-09-01), None
patent: 39 11 505 A1 (1990-10-01), None
patent: 41 06 331 A1 (1991-09-01), None
patent: 40 21 663 A1 (1992-01-01), None
patent: 0 773 623 A1 (1997-05-01), None
patent: 09110298A (1997-04-01), None
Haasen Rolf
Hermanns Ferdinand-Josef
Wedershoven Hans-Gunter
Kennedy Covington Lobdell & Hickman L.L.P.
Leykin Rita
Nappi Robert E.
W. Schlafhorst AG & Co.
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