Electrical generator or motor structure – Dynamoelectric – Linear
Reexamination Certificate
2000-05-26
2002-06-04
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Linear
Reexamination Certificate
active
06400046
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a linear motor driver, and more particularly to a linear motor driver for driving a permanent magnet movable type linear motor by partly exciting a movable element employed therein.
2. Description of the Conventional Art
Generally speaking, a linear motor employs a stator containing coil block and a movable element containing permanent magnets. The coil block and the permanent magnets are installed parallel to each other in a horizontal direction, respectively, so that the coil block faces the permanent magnets.
The supply of an electric current into the coil block of the stator generates a thrust force between the coil block and the permanent magnets under Fleming's left-hand rule. The generated thrust force permits direct linear motion of the movable element along the longitudinal direction of the stator.
A conventional linear motor made it possible such a direct linear movement is disclosed in U.S. Pat. No. 4,595,870, which will be described below.
FIGS. 1 and 2
used in the referenced patent application are also here shown, in which
FIG. 1
is a perspective view of a linear motor according to the prior art, and
FIG. 2
is a control system for the linear motor shown in FIG.
1
.
FIG. 1
shows a configuration of the conventional typical linear motor
10
. The linear motor shown in
FIG. 1
includes a U-shaped channel
12
and a movable element
18
. The U-shaped channel
12
mounted on a mounting surface (not shown) encloses a wound stator
16
. On an upper surface of wound stator
16
, the movable element
18
is disposed to be moved in a direction indicated by a double-headed arrow
22
.
Movable element
18
includes a plurality of permanent magnets (not shown) facing upper surface
20
of wound stator
16
for producing a magnetic field for interaction with the magnetic field produced by the coil block (not shown) of wound stator.
Referring to
FIG. 2
, a control system is employed which controls generation of magnetic fields between the stator
16
containing coil block and the movable element
18
containing a plurality of permanent magnets, and further controls a thrust force created due to interaction between the magnetic fields produced.
Control system
28
receives commands from a host (not shown). Upon receipt of commands, control system
28
receives through information channel
30
positional information representing positional relationship between the permanent magnets
32
of movable element
18
and respective coils
24
a
,
24
b
,
24
c
of the stator
16
, and in response thereto, the control system
28
selectively controls the switches
26
a
,
26
b
,
26
c to control an application of power supply into each of coils
24
a
,
24
b
,
24
c.
On the other hand, the above-described control system, which is used to selectively control said switches
26
a
,
26
b
,
26
c
, receives information through the information channel
30
when the movable element
18
leaves the coil
24
a
, and in response thereto, opens the switch
26
a
connected the coil
24
a
to block the supply of the power supply. Namely, the control system
28
serves to partly excite the respective coils
24
a
,
24
b
,
24
c
based upon the movement of the movable element
18
.
The above-described prior art uses a magnetic sensor and a Hall-effect device (not shown) in order to partly excite the respective coils
24
a
,
24
b
,
24
c
provided to the stator
16
. In the case of the use of such a magnetic sensor and the Hall-effect device, the magnetic fields from the permanent magnets in the movable element causes an erroneous operation of the Hall-effect device, which results in malfunction of the linear motor.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a driver for a linear motor which senses position of movable element to partly excite coils provided to a stator, with the influence of magnetic fields from permanent magnets directly associated with thrust force of the linear motor being minimized.
Further, another object of the present invention is to reduce power consumption by partly exciting respective coils of the stator and to minimize heat generation by selectively exciting respective coils.
To accomplish the above-mentioned objects, this invention provides a driver for a linear motor, the driver comprising: a stator having coil block and disposed on an inner bottom surface of a U-shaped frame; a movable element having a plurality of permanent magnets at an armature frame; a shield member provided on one side surface of the movable element, and having a magnet sensing unit formed on one side surface thereof for blocking magnet fields generated from the plurality of permanent magnets; and a controller board disposed on an inner wall of the U-shaped frame, and for sensing magnet fields generated from the magnet sensing unit to selectively supply an electric current into the coil block.
Thus, an erroneous recognition of the position of the movable element can be prevented which may occur due to the magnet fields generated from the permanent magnets used for creating a thrust force of the motor. Therefore, an optimum driving condition for the linear motor can be accomplished. Further, by partly exciting the coils to drive the movable element, the power consumption by the coils can be reduced, and heat generated when the current flows into the coils can be minimized.
REFERENCES:
patent: 4595870 (1986-06-01), Chitayat
patent: 5977664 (1999-11-01), Chitayat
patent: 6008552 (1999-12-01), Yagoto et al.
patent: 6259220 (2001-07-01), Hays et al.
Chun Jang Sung
Hwang Ji Hyun
Kim Do Hyun
Fleshner & Kim LLP
Jones Judson H.
Mirae Corporation
Ramirez Nestor
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