Sliding means with built-in moving-magnet linear motor
First Claim
1. A sliding means with built-in moving-magnet linear motor, comprising a bed and a table constituting paired members arranged for sliding movement relatively of each other, the table being movable lengthwise of the bed in a sliding manner with respect to the bed, a field magnet having unlike magnetic end poles juxtaposed alternately in polarity in a moving direction of the table, an armature winding assembly having armature windings installed on the bed in opposition to the field magnet, a magnetic sensor element installed on the bed in opposition to the field magnet to monitor a strength and direction of magnetic flux, and an auxiliary magnet arranged adjoining to one of the magnetic end poles of the field magnet and magnetized in a polarity opposite to the polarity of the one of the end poles, wherein a current in each armature winding interacts with magnetic flux created by the field magnet to produce an electromagnetic force to apply propulsion to the field magnet to drive the table with a desired position control, and the auxiliary magnet makes up for the magnetic flux at the one of the end poles of the field magnet, thereby making the magnetic sensor element detect an accurate position of the field magnet,wherein the field magnet is made of rare earth magnet and has therein the magnetic poles of a multiple of 4, which are juxtaposed alternately in polarity.
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Accused Products
Abstract
A sliding means with built-in moving-magnet linear is disclosed, which makes it possible to sense accurately a table position with a magnetic sensor element. To this end, a magnetic flux pattern is rectified outside any one N-pole of forward and aft end poles of a field magnet. Position of the table is monitored with a magnetic sensor element arranged on the bed in opposition to the field magnet. Arranged outside the end pole of the field magnet is an auxiliary magnet unlike in polarity and made as small as possible in effect on propulsion exerted on the table. The auxiliary magnet is to rectify the magnetic flux pattern outside the end pole of the field magnet to the same distribution pattern as found at a boundary between the adjacent poles opposite in polarity in the field magnet, thus making it possible to identify the accurate positions of the forward and aft end pole of the field magnet.
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Citations
16 Claims
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1. A sliding means with built-in moving-magnet linear motor, comprising a bed and a table constituting paired members arranged for sliding movement relatively of each other, the table being movable lengthwise of the bed in a sliding manner with respect to the bed, a field magnet having unlike magnetic end poles juxtaposed alternately in polarity in a moving direction of the table, an armature winding assembly having armature windings installed on the bed in opposition to the field magnet, a magnetic sensor element installed on the bed in opposition to the field magnet to monitor a strength and direction of magnetic flux, and an auxiliary magnet arranged adjoining to one of the magnetic end poles of the field magnet and magnetized in a polarity opposite to the polarity of the one of the end poles, wherein a current in each armature winding interacts with magnetic flux created by the field magnet to produce an electromagnetic force to apply propulsion to the field magnet to drive the table with a desired position control, and the auxiliary magnet makes up for the magnetic flux at the one of the end poles of the field magnet, thereby making the magnetic sensor element detect an accurate position of the field magnet,
wherein the field magnet is made of rare earth magnet and has therein the magnetic poles of a multiple of 4, which are juxtaposed alternately in polarity.
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11. A sliding means with built-in moving-magnet linear motor, comprising a bed and a table constituting paired members arranged for sliding movement relatively of each other, the table being movable lengthwise of the bed in a sliding manner with respect to the bed, a field magnet having unlike magnetic end poles juxtaposed alternately in polarity in a moving direction of the table, an armature winding assembly having armature windings installed on the bed in opposition to the field magnet, a magnetic sensor element installed on the bed in opposition to the field magnet to monitor a strength and direction of magnetic flux, and an auxiliary magnet arranged adjoining to one of the magnetic end poles of the field magnet and magnetized in a polarity opposite to the polarity of the one of the end poles, wherein a current in each armature winding interacts with magnetic flux created by the field magnet to produce an electromagnetic force to apply propulsion to the field magnet to drive the table with a desired position control, and the auxiliary magnet makes up for the magnetic flux at the one of the end poles of the field magnet, thereby making the magnetic sensor element detect an accurate position of the field magnet,
wherein the auxiliary magnet is made less in width in the sliding direction than a width of a coil side of the armature winding to reduce any effect on propulsion rendered to the table.
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12. A sliding means with built-in moving-magnet linear motor, comprising a bed and a table constituting paired members arranged for sliding movement relatively of each other, the table being movable lengthwise of the bed in a sliding manner with respect to the bed, a field magnet having unlike magnetic end poles juxtaposed alternately in polarity in a moving direction of the table, an armature winding assembly having armature windings installed on the bed in opposition to the field magnet, a magnetic sensor element installed on the bed in opposition to the field magnet to monitor a strength and direction of magnetic flux, and an auxiliary magnet arranged adjoining to one of the magnetic end poles of the field magnet and magnetized in a polarity opposite to the polarity of the one of the end poles, wherein a current in each armature winding interacts with magnetic flux created by the field magnet to produce an electromagnetic force to apply propulsion to the field magnet to drive the table with a desired position control, and the auxiliary magnet makes up for the magnetic flux at the one of the end poles of the field magnet, thereby making the magnetic sensor element detect an accurate position of the field magnet,
wherein the table is provided with an origin mark to define an origin of the table, and a sensor magnet arranged adjoining to the magnetic end pole fore-and-aft opposite to the auxiliary magnet and magnetized in a polarity unlike the associated magnetic end pole, while the bed is provided with an origin sensor to detect the origin mark, and the armature winding assembly is mounted with a before-the-origin sensor to respond to the sensor magnet at a before-the-origin position just before the origin sensor detects the origin during a linear movement of the table along the bed, and a limit sensor to respond any one of the magnetic end poles and the sensor magnet when the table reaches any dead end position of a tolerated stroke range.
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16. A sliding means with built-in moving-magnet linear motor, comprising a bed and a table constituting paired members arranged for sliding movement relatively of each other, the table being movable lengthwise of the bed in a sliding manner with respect to the bed, a field magnet having unlike magnetic end poles juxtaposed alternately in polarity in a moving direction of the table, an armature winding assembly having armature windings installed on the bed in opposition to the field magnet, a magnetic sensor element installed on the bed in opposition to the field magnet to monitor a strength and direction of magnetic flux, and an auxiliary magnet arranged adjoining to one of the magnetic end poles of the field magnet and magnetized in a polarity opposite to the polarity of the one of the end poles, wherein a current in each armature winding interacts with magnetic flux created by the field magnet to produce an electromagnetic force to apply propulsion to the field magnet to drive the table with a desired position control, and the auxiliary magnet makes up for the magnetic flux at the one of the end poles of the field magnet, thereby making the magnetic sensor element detect an accurate position of the field magnet,
wherein the table is provided with an end plate at a position adjoining the auxiliary magnet to keep the magnetic flux established in the field magnet against leakage.
Specification