Electricity: motive power systems – Plural diverse motor controls – Motor braking
Reexamination Certificate
2000-06-09
2001-10-30
Nappi, Robert E. (Department: 2834)
Electricity: motive power systems
Plural diverse motor controls
Motor braking
C318S286000, C318S371000, C318S375000
Reexamination Certificate
active
06310452
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to positioning systems and, more particularly, to an improved single cycle positioning system which utilizes a DC motor to accurately position a cyclicly movable member at a precise location within its movement cycle.
There are numerous machines where a member is cyclicly driven and it is required to stop the member at a precise location within its positional cycle. One such type of machine is a crimping press which is utilized repetitively to attach electrical terminals to the ends of wires. U.S. Pat. No. 3,343,398 discloses one such machine wherein a ram is coupled to a shaft and, during each single revolution of the shaft, the ram is moved downwardly and then back to its initial position thereby to move a crimping die on the end of the ram into engagement with a terminal. The shaft is coupled through a single revolution clutch to a flywheel which is continuously driven by a continuously operated motor. When it is desired to crimp a terminal onto a wire, the single revolution clutch is engaged to drive the shaft through a single revolution so that the ram is moved through its cycle.
While the aforedescribed arrangement is effective for its intended purpose, it suffers from a number of disadvantages. Thus, for example, the continuous running of the motor is wasteful of electrical energy and results in the generation of heat. Also, the use of a single revolution clutch causes noise and vibration. Further, the clutch has to be properly maintained and worn parts replaced.
U.S. Pat. No. 5,449,990, discloses a single cycle positioning system which substitutes electronic control of an induction motor for a single revolution clutch. While effective and well received in the industry, the electronic control system for operating the induction motor is relatively expensive. It would therefore be desirable to provide a lower cost single cycle positioning system of the type described.
SUMMARY OF THE INVENTION
In accordance with this invention, there is provided a single cycle positioning system utilizing a DC motor having a winding with two ends. The system comprises a source of DC power, a movable member coupled to the motor for controlled cyclical movement thereby, means for providing a start signal to initiate movement of the member, and means associated with the member for providing a stop signal when the member is at a predetermined position within its cycle of movement. A motor controller in the system includes a first switch coupled between the DC power source and a first end of the motor winding, a second switch coupled between the second end of the motor winding and a reference level, and a third switch coupled between a first end of the motor winding and the reference level. The system also includes a control means coupled to receive the start signal and the stop signal for controlling the motor control switches. The control means is operative in response to the start signal for controlling closure of the first and second switches so as to apply DC power to the winding of the motor. The control means is operative in response to the stop signal for opening the first switch and closing the second and third switches to effect a dynamic braking of the motor so that the movable member comes to rest at a desired position within a defined range of the predetermined position.
In accordance with an aspect of the present invention, the source of DC power includes a pair of terminals connected to a source of AC power and rectification means coupled to the pair of terminals and effective to convert AC power applied to the terminals to DC power. The control means is operative to determine the AC voltage across the pair of terminals and to pulse width modulate closure of the second switch at a rate inversely related to the determined AC voltage so as to provide a predetermined effective DC voltage across the motor winding after receipt of the start signal and before receipt of the stop signal.
REFERENCES:
patent: 3343398 (1967-09-01), Kerns
patent: 3694721 (1972-09-01), Henry
patent: 3819997 (1974-06-01), Morton et al.
patent: 3911342 (1975-10-01), Herwig
patent: 4124812 (1978-11-01), Naito et al.
patent: 4132934 (1979-01-01), Morton et al.
patent: 4633154 (1986-12-01), Maeda
patent: 5033187 (1991-07-01), Gloe et al.
patent: 5449990 (1995-09-01), Bowling et al.
patent: 5789885 (1998-08-01), Seel
patent: 5831403 (1998-11-01), Kanki et al.
Deck Gary Lee
Pfautz Douglas Sebastian
Strong Michael David
Leykin Rita
Nappi Robert E.
Tyco Electronics Corp
LandOfFree
Single cycle positioning system utilizing a DC motor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Single cycle positioning system utilizing a DC motor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Single cycle positioning system utilizing a DC motor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2602181