Non-contact rotational position sensor and throttle valve assembly including non-contact rotational position sensor
First Claim
1. A non-contact rotational position sensor comprising;
- a permanent magnet having a circular or arc-shaped outer circumference;
a shaft for supporting and fixing said permanent magnet;
upper and lower magnetic plates sandwiching said permanent magnet from above and below, at least one of said upper and lower magnetic plates being horizontally separated from each other with an air gap formed therebetween;
at least one protruded magnetic substance portion disposed between said upper and lower magnetic plates; and
a magnetic sensitive device disposed on a protruded surface of said protruded magnetic substance portion, said permanent magnet and said shaft constituting a rotor which is rotatable relative to said upper and lower magnetic plates vertically spaced from each other, said permanent magnetic being magnetized substantially in the direction of a rotating axis, whereby the amount of magnetic flux passing said magnetic sensitive device is varied with rotation of said permanent magnet.
1 Assignment
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Accused Products
Abstract
A non-contact sensor for sensing a rotational position of a rotating object is provided. A ring-shaped permanent magnet magnetized in the axial direction is sandwiched between two pairs of magnetic plates from above and below. Two pairs of upper and lower protruded magnetic substance portions are provided between the upper and lower magnetic plates at opposite outer ends thereof. Magnetic sensitive devices are inserted in air gaps between the two pairs of upper and lower protruded magnetic substance portions. A magnetic flux generated from the ring-shaped permanent magnet is substantially concentrated to the protruded magnetic substance portions and passes the magnetic sensitive devices. The amount of magnetic flux passing each magnetic sensitive device is substantially proportional to the rotational angle of the ring-shaped permanent magnet. The rotational position of the ring-shaped permanent magnet and hence the rotational position of a rotating shaft supporting the ring-shaped permanent magnet can be sensed in a non-contact manner as a signal output from the magnetic sensitive device. Since the magnetic flux is effectively concentrated to positions where magnetic sensitive devices are attached, a non-contact rotational position sensor having high accuracy and high sensitivity can be obtained.
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Citations
28 Claims
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1. A non-contact rotational position sensor comprising;
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a permanent magnet having a circular or arc-shaped outer circumference;
a shaft for supporting and fixing said permanent magnet;
upper and lower magnetic plates sandwiching said permanent magnet from above and below, at least one of said upper and lower magnetic plates being horizontally separated from each other with an air gap formed therebetween;
at least one protruded magnetic substance portion disposed between said upper and lower magnetic plates; and
a magnetic sensitive device disposed on a protruded surface of said protruded magnetic substance portion, said permanent magnet and said shaft constituting a rotor which is rotatable relative to said upper and lower magnetic plates vertically spaced from each other, said permanent magnetic being magnetized substantially in the direction of a rotating axis, whereby the amount of magnetic flux passing said magnetic sensitive device is varied with rotation of said permanent magnet. - View Dependent Claims (2, 3, 4, 5, 6, 7, 10, 11, 12, 14, 16, 17, 18, 19, 20, 21)
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8. A non-contact rotational position sensor comprising;
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a permanent magnet having a circular or arc-shaped outer circumference;
a shaft for supporting and fixing said permanent magnet;
magnetic plates sandwiching said permanent magnet from opposite outer sides in the radial direction;
a magnetic circuit having a portion formed by narrowing part of each of said magnetic plates for concentrating a magnetic flux generated from said permanent magnet;
an air gap formed at a fore end of the magnetic flux concentrating portion of said magnetic circuit; and
a magnetic sensitive device disposed in said air gap, said permanent magnet and said shaft constituting a rotor which is rotatable relative to said magnetic plates arranged outwardly of said permanent magnet in the radial direction, said permanent magnetic being magnetized substantially in the radial direction, whereby the amount of magnetic flux passing said magnetic sensitive device is varied with rotation of said permanent magnet. - View Dependent Claims (9)
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13. A non-contact rotational position sensor comprising a permanent magnet as a magnetic field generating source, a magnetic substance yoke for forming a magnetic path, and a magnetic sensitive device for detecting a magnetic field, wherein a magnetic substance cover is attached to a housing cover of said non-contact rotational position sensor, or another dedicated cover is disposed on a housing cover of said non-contact rotational position sensor and a magnetic substance cover is attached to said dedicated cover, said magnetic substance cover preventing any external magnetic substance situated near said non-contact rotational position sensor from affecting a magnetic flux density signal detected by said magnetic sensitive device.
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15. A non-contact rotational position sensor comprising;
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a rotating axis;
an annular or semi-annular magnet fixed to said rotating axis;
magnetic substance assemblies arranged in opposing relation to sandwich said magnet therebetween with a spacing greater than a thickness of said magnet left between said magnetic substance assemblies in the axial direction of said rotating axis, such that a uniform air gap is formed between said magnet and a surface of each of said magnetic substance assemblies confronting said magnet;
a pair of small air gaps formed in said magnetic substance assemblies and being smaller than said air gap; and
a magnetic sensitive device disposed in said small air gap.
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22. A throttle valve assembly comprising:
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an annular or semi-annular magnet attached to one end of a throttle valve;
a resin cover attached to a body in which said throttle valve is mounted;
an auxiliary caver attached to said resin cover;
magnetic path forming members attached to said resin cover and said auxiliary cover, respectively, and forming magnetic paths with said annular or semi-annular magnet situated therebetween;
a magnetic flux converging portion formed in each of said magnetic paths and concentrating a magnetic flux passing said magnetic path to a particular position; and
a magnetic sensitive device attached to said magnetic flux converging portion and detecting change of the magnetic flux in said magnetic flux converging portion caused upon rotation of said throttle valve. - View Dependent Claims (23, 24, 25)
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26. A non-contact rotational position sensor comprising:
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a permanent magnet;
a magnetic path member allowing a magnetic flux generated from said permanent magnet to pass therethrough;
a magnetic sensitive device disposed in said magnetic path and detecting change of the magnetic flux in said magnetic path caused upon relative rotation between said magnetic path member and said permanent magnet; and
a slit formed in said magnetic path member for adjusting a nonlinear characteristic between change of the magnetic flux in said magnetic path and a rotational angle resulted from the relative rotation between said magnetic path member and said permanent magnet.
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27. A non-contact rotational position sensor comprising:
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a permanent magnet;
a magnetic path member allowing a magnetic flux generated from said permanent magnet to pass therethrough;
a magnetic sensitive device disposed in said magnetic path and detecting change of the magnetic flux in said magnetic path caused upon relative rotation between said magnetic path member and said permanent magnet; and
a magnetic resistance forming slit formed in said magnetic path member for converging the magnetic flux passing said magnetic path member to a position where said magnetic sensitive device is attached.
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28. A non-contact rotational position sensor comprising:
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a permanent magnet;
a magnetic path member allowing a magnetic flux generated from said permanent magnet to pass therethrough;
a magnetic flux converging portion provided in said magnetic path member for converging the magnetic flux passing said magnetic path member to a particular position;
a magnetic sensitive device disposed in said magnetic flux converging portion and detecting change of the magnetic flux in said magnetic path caused upon relative rotation between said magnetic path member and said permanent magnet; and
a magnetic member for magnetic shielding arranged to surround said magnetic path member in a non-contact state with respect to said magnetic path member.
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Specification