US3758859A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic tachometer pickup
Assignee: Motorola Solutions Inc
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Filing: 1971-10-29
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Granted: 1973-09-11
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Expires: 1991-10-29
Abstract
Abstract An encapsulated magnetic tachometer pickup for insertion in an aperture of a fuel or oil pump housing for detecting the rotational speed of a gear in the pump which is driven in proportion to engine RPM includes a pole piece adapter substantially perpendicular to and radially extending from the axis of the pole piece and connected thereto. The adapter is positioned to have the teeth of the pump gear move transversely across its sensing portion when the gear rotates. A magnet connected to the pole piece causes a magnetic field to be generated in the pole piece and pole piece adapter which changes as the result of the rotation of the gear across the sensing portion of the pole piece adapter. The changing flux induces a current in a coil mounted on the pole piece which in turn is connected to a signal translating network for indicating engine RPM.
Inventors
- 👤 A Damijonaitis
- 👤 D Wiley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 06:22
CPC Classifications
G; G01; G01P; G01P3/00; G01P3/42; G01P3/44; G01P3/48; G01P3/481; G01P3/488
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
224 words
A tachometer pickup for use in an engine having fuel and oil pumps, a gear mounted in one of said fuel and oil pumps for rotation about an axis, the gear being driven in proporTion to engine RPM, said one of said pumps having an aperture through the wall of its housing, with the axis of the aperture being substantially perpendicular to the axis of the gear, said axes being displaced from one another, the tachometer pickup including in combination, a magnetic pickup mounted in a casing which is inserted in said aperture, said magnetic pickup including a core having a magnet for providing a magnetic field therein, a coil mounted on said core, an adapter of flux conducting material secured to said core and extending radially therefrom toward and substantially normal to the axis of said gear, said adapter having a sensing area in proximity to the gear, said casing having a flattened area formed at the free end thereof, said flattened area being undercut toward the axis of said casing a distance sufficient to maintain said casing mechanically free of the gear being positioned adjacent thereto, whereby the rotation of the gear causes magnetic flux in said sensing area of said adapter to change, thereby causing a change in the magnetic flux of the core and inducing a current in said coil.
Claim 2
Dependent Claim
224 words
A tachometer pickup for use in an engine having fuel and oil pumps, a gear mounted in one of said fuel and oil pumps for rotation about an axis, the gear being driven in proporTion to engine RPM, said one of said pumps having an aperture through the wall of its housing, with the axis of the aperture being substantially perpendicular to the axis of the gear, said axes being displaced from one another, the tachometer pickup including in combination, a magnetic pickup mounted in a casing which is inserted in said aperture, said magnetic pickup including a core having a magnet for providing a magnetic field therein, a coil mounted on said core, an adapter of flux conducting material secured to said core and extending radially therefrom toward and substantially normal to the axis of said gear, said adapter having a sensing area in proximity to the gear, said casing having a flattened area formed at the free end thereof, said flattened area being undercut toward the axis of said casing a distance sufficient to maintain said casing mechanically free of the gear being positioned adjacent thereto, whereby the rotation of the gear causes magnetic flux in said sensing area of said adapter to change, thereby causing a change in the magnetic flux of the core and inducing a current in said coil.
Claim 3
Dependent Claim
15 words
The tachometer pickup arrangement according to claim 1 wherein said magnet comprises a permanent magnet.
Claim 4
Dependent Claim
205 words
In a diesel engine system having a tachometer and a pump with a helical gear therein driven in relation to the engine RPM, said pump having a housing with an aperture for receiving a mechanical pickup for the engine tachometer, which pickup meshes with the gear in the pump for mechanically sensing the engine RPM and transmitting the same to the tachometer, the pump housing further having means for securing the mechanical tachometer pickup thereto with the same being fitted into the aperture therein, the combination including a magnetic tachometer pickup for replacing the mechanical pickup, said magnetic pickup including a magnet, a pole piece connected to said magnet, a coil mounted on said pole piece with changes in magnetic flux in said pole piece inducing a current in said coil, mounting means for mounting said magnetic pickup in the aperture of the pump housing in a spaced relation to the gear therein, said mounting means utilizing the means provided on the housing for securing the mechanical tachometer pickup to the housing, whereby movement of the gear by the engine generates pulses in said pickup in relation to engine RPM, and circuit means responsive to the pulses for operating a tachometer for indicating engine RPM.
Claim 5
Dependent Claim
205 words
In a diesel engine system having a tachometer and a pump with a helical gear therein driven in relation to the engine RPM, said pump having a housing with an aperture for receiving a mechanical pickup for the engine tachometer, which pickup meshes with the gear in the pump for mechanically sensing the engine RPM and transmitting the same to the tachometer, the pump housing further having means for securing the mechanical tachometer pickup thereto with the same being fitted into the aperture therein, the combination including a magnetic tachometer pickup for replacing the mechanical pickup, said magnetic pickup including a magnet, a pole piece connected to said magnet, a coil mounted on said pole piece with changes in magnetic flux in said pole piece inducing a current in said coil, mounting means for mounting said magnetic pickup in the aperture of the pump housing in a spaced relation to the gear therein, said mounting means utilizing the means provided on the housing for securing the mechanical tachometer pickup to the housing, whereby movement of the gear by the engine generates pulses in said pickup in relation to engine RPM, and circuit means responsive to the pulses for operating a tachometer for indicating engine RPM.
Claim 6
Dependent Claim
35 words
The magnetic pickup according to claim 3 wherein said mounting means includes a casing having flange portions with indexing means, and mounting studs fitting said indexing means for securing said flange portion to the pump.
Claim 7
Dependent Claim
32 words
The magnetic pickup according to claim 3 wherein said pickup includes fingers projecting therefrom, said fingers sensing changes in magnetic flux with teeth of said helical gear passing said fingers substantially simultaneously.
Claim 8
Dependent Claim
24 words
The combination according to claim 3 wherein said pickup extends into the aperture, said pickup being substantially normal to the axis of said gear.
References Cited (Backward Citations)
CA613185A
Cited
US3581561A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-10 | 1977-03-12 | 1977-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-10 | 1981-03-12 | 1981-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-10 | 1985-03-12 | 1985-09-11 | $7700.00 | Window Closed / Lapsed |