Linear shuttle motor assembly and a controller therefor

Details Linear shuttle motor assembly and a controller therefor Linear shuttle motor assembly and a controller therefor

2000-02-22

2001-05-29

Ramirez, Nestor (Department: 2853)

Electrical generator or motor structure

Dynamoelectric

Linear

C400S322000, C101S093040, C310S017000

Reexamination Certificate

active

06239517

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a linear shuttle motor assembly and a controller for controlling the same, wherein the linear shuttle motor is used for linearly moving a load, such as a print head, at a high speed back and forth between two extremes.
2. Description of the Related Art
Heretofore, some printers employ linear motor assemblies which include a stator made up of permanent magnets, and a rotor made up of coils. The stator is fixedly mounted on a printer housing. The rotor is driven in accordance with the principal of Fleming's left-hand rule. A print head is connected to the rotor so as to move reciprocally with reciprical movement of the rotor. In order to suppress generation of moment in the stationary components but obtain couple, a counter balance is connected to the rotor through a vector force conversion mechanism. The drive force of the rotor is transmitted through the vector force conversion mechanism to the counter balance, to recriprically move the rotor and the counter balance in opposite directions in order to maintain a fixed center of gravity for the overall system.
The conventional linear shuttle motor assembly requires a great deal of thrust, because so much thrust is consumed to move the rotor, the print head, and the counter balance and because so much thrust is wasted as transmission loss in the vector force conversion mechanism. In particular, inertial force must be overcome each time the print head reverses movement direction during its reciprical transport. In order to generate repulsion thrust that overcomes the inertial force, it was required that a reverse drive be operated with a large current, say about 20 Amperes, with a D.C. power source generating 40 volts.
A further disadvantage exists in that the transmission loss at the vector force conversion mechanism increases instantaneously each time the head transport direction is reversed. This high transmission loss causes wearing down of the vector force conversion mechanism by abrasion. In order to relieve such disadvantages, it has been proposed to use repulsion springs or repulsion magnets to weaken inertial force generated at the time when the rotor reverses its direction and to supplement repulsion thrust.
SUMMARY OF THE INVENTION
It is an objective of the present invention to provide a linear shuttle motor assembly that reduces power transmission loss and driving energy required when the print head reverses direction, so that energy conversion efficiency is improved without the need for an urging means of some kind.
The above-described objectives can be achieved using the following configuration:
1. A motor is configured from a rotor and a stator having the same mass or weight. The rotor and the stator are supported to be reciprocally movable along the same axis and between two extremes, and are driven to reciprocally move in mutually opposite directions while maintaining a positional relationship such that a distance from one extreme to the center of rotor is equal to a distance from the other extreme to the center of stator. A 180 degree phase synchronizing mechanism is used to synchronize phases of the rotor and the stator. The 180 degree phase synchronizing mechanism is fixed to the housing of the linear shuttle motor assembly, and connected to the rotor and the stator.
2. The rotor includes permanent magnets that are juxtaposed in a line, which defines the axis of the rotor. Ferromagnetic material is disposed between adjacent magnets. The magnets are oriented with the same poles in confrontation. With this configuration, magnetic lines of force are concentrated and extend in a direction perpendicular to the axis of the rotor.
3. The stator includes a pair of permanent magnets, one magnet being attached to each end of the stator. The magnets of the stator and the rotor are oriented with the same poles, that is, repelling poles, facing each other. That is, either the N pole of the stator magnet faces the N pole of the end rotor magnet, or the S pole of the stator magnet faces the S pole of the end rotor magnet. Also, four solenoids, that is, a fixed-speed solenoid, a reversing solenoid, a left-end solenoid, and a right-end solenoid, are attached around the periphery of the stator, at positions as shown in FIGS.
2
(
a
) to
2
(
h
).
4. A variety of components are provided for driving the linear shuttle motor assembly. That is, a fixed-speed solenoid drive, a reversing solenoid drive, left- and right-end solenoid drives, a stop controller, a start controller, a fixed-speed controller, and a reversal controller are provided for driving the linear shuttle motor assembly.
5. An auxiliary magnetic circuit can be provided around the exterior periphery of the solenoids to increase the density of magnetic flux that are out by the solenoids.


REFERENCES:
patent: 5229670 (1993-07-01), Kagawa
patent: 5281880 (1994-01-01), Sakai
patent: 5338121 (1994-08-01), Kobayashi et al.

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