EP0190918A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Position sensor/tachometer
Assignee: Garrett Corp
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Filing: 1986-02-04
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Granted: —
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Expires: 2006-02-04
Abstract
Abstract A sensor for use with a d.c. brushless motor or other electrical device is disclosed which provides both angular position information and rate of rotation information from an integrated device. The device, which is preferably mounted at the end of the motor (82), uses a ferrite rotor (70) to connect the flux path between a single primary coil (30) and six secondary coils (32-42) arranged in reverse polarity pairs configuration (Figure 5). The resulting waveform (Figure 7) includes zero crossings and relatively straight rising and failing edges, with the zero crossings being used to provide information (at 104) used to electronically commutate (at 94) the d.c. brushless motor, and the rising and falling edges of the waveform providing (at 92) information about the speed of the motor.
Inventors
- 👤 Richard Keith Larsen
- 👤 Frederick Briggs Mccarty
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 04:50
CPC Classifications
H; H01; H01F; H01F29/00; H01F29/08; H01F29/10; G; G01; G01P; G01P3/00; G01P3/42; G01P3/44; G01P3/48; G01P3/481; H02; H02K; H02K29/00; H02K29/06; H02K29/12
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
64 words
A sensor, for example for sensing the instantaneous angular position and/or the speed of rotation of a rotating shaft (84), comprising a stator (20) having primary (301 and secondary (32-42) coils, and a rotor (70) arranged when rotating to vary cyclicly the magnetic coupling between the coils, whereby an output (7, 8) from the secondary coil is characteristic of the rotor speed and/or position.
Claim 2
Dependent Claim
64 words
A sensor, for example for sensing the instantaneous angular position and/or the speed of rotation of a rotating shaft (84), comprising a stator (20) having primary (301 and secondary (32-42) coils, and a rotor (70) arranged when rotating to vary cyclicly the magnetic coupling between the coils, whereby an output (7, 8) from the secondary coil is characteristic of the rotor speed and/or position.
Claim 3
Dependent Claim
34 words
A sensor as claimed in Claim 1 in which the stator (20) has a magnetisable core (50) e.g. of moulded ferrite,having discrete core segments (54,56 - 66) for the primary and secondary coils (30,32-42).
Claim 4
Dependent Claim
21 words
A sensor as claimed in Claim 2 in which the core segments are open-ended,enabling pre-wound coils to be placed over them.
Claim 5
Dependent Claim
41 words
A sensor as claimed in Claim 2 or Claim 3 in which there is a single primary coil core segment (54) and spaced secondary coil core segments (56-66) arranged in a sector of an annulus around the primary coil core segment.
Claim 6
Dependent Claim
30 words
A sensor as claimed in Claim 4 in which the primary coil core segment (54) has an opening (52) for a shaft,the characteristics of whose rotation are to be sensed.
Claim 7
Dependent Claim
32 words
A sensor as claimed in any of Claims 3 to 5 in which the rotor is arranged to rotate in a plane closely spaced from the open ends of the core segments.
Claim 8
Dependent Claim
52 words
A sensor as claimed in any of the preceding claims in which the rotor (70) is of magnetisable material e.g. of moulded ferrite, and has a body portion adjacent the primary coil core segment (54) and one or more lobes which pass adjacent the secondary coil core segments as the rotor rotates.
Claim 9
Dependent Claim
51 words
A sensor as claimed in Claim 7 in which the, or each,rotor lobe has an angular arcuate extent at one radial extremity of the secondary coil core segments of B and an angular arcuate extent at the other radial extremity of the secondary coil core segments of B + 2 0.
Claim 10
Dependent Claim
46 words
A sensor as claimed in any of the preceding claims arranged so that as the rotor rotates the output over at least a part of a cycle will increase or decrease substantially linearly at a rate related to the speed of rotation of the rotor (70).
Claim 11
Dependent Claim
53 words
A sensor as claimed in any of the preceding claims in which there are a plurality of secondary coils (32-42), the two coils of each pair being electrically connected with their outputs in opposition to produce from each pair an output having zero crossing points where the increasing or decreasing output changes sign.
Claim 12
Dependent Claim
25 words
A sensor as claimed in Claim 10 in which the outputs from all the pairs of secondary coils are combined to provide a sensor output.
Claim 13
Dependent Claim
56 words
A sensor as claimed in any of the preceding claims having its rotor connected to be rotated by a shaft whose speed of rotation and/or instantaneous angular position is to be sensed, for example the shaft of an electrical machine,for example a brushless d.c. motor controlled by cyclicly switching the power supply to its stator windings.
Claim 14
Independent Claim
37 words
A method of measuring the speed of rotation and/or the instantaneous angular position of a rotating shaft using a sensor as claimed in any preceding Claim of which the rotor (70) is rotated by the shaft (84)
Claim 15
Dependent Claim
36 words
A method as claimed in Claim 13 in which the primary coil (30) of the sensor is energised at a frequency at least several times the frequency at which a motor driving the shaft is driven.
Claim 16
Independent Claim
66 words
A method of controlling a brushless d.c. machine having windings arranged to be cyclicly switched to and from a d.c. supply,in which a sensor as claimed in any of Claims 1-12 has its rotor (70) driven by the motor shaft (84) and in which the output (Figure 7,8) from the secondary coils (32-42) is used to define the instants at which the motor windings are switched.
Claim 17
Independent Claim
46 words
A method of controlling the speed of an electric motor in which the motor shaft drives the rotor of a sensor as claimed in any of Claims 1-12 and the output from the sensor is used to provide a feedback signal related to the motor speed.
References Cited (Backward Citations)
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