US3348181A - Broadband rotary transformer - Google Patents

Broadband rotary transformer Download PDF

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Publication number
US3348181A
US3348181A US450980A US45098065A US3348181A US 3348181 A US3348181 A US 3348181A US 450980 A US450980 A US 450980A US 45098065 A US45098065 A US 45098065A US 3348181 A US3348181 A US 3348181A
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US
United States
Prior art keywords
primary
conductor
loop
coupling
rotary transformer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US450980A
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English (en)
Inventor
Stromswold Chester
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Lockheed Martin Corp
Original Assignee
Sanders Associates Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sanders Associates Inc filed Critical Sanders Associates Inc
Priority to US450980A priority Critical patent/US3348181A/en
Priority to GB15948/66A priority patent/GB1111464A/en
Priority to DE19661563330 priority patent/DE1563330A1/de
Priority to NL6605587A priority patent/NL6605587A/xx
Application granted granted Critical
Publication of US3348181A publication Critical patent/US3348181A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
    • H01F38/18—Rotary transformers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F19/00—Fixed transformers or mutual inductances of the signal type
    • H01F19/04—Transformers or mutual inductances suitable for handling frequencies considerably beyond the audio range
    • H01F19/06—Broad-band transformers, e.g. suitable for handling frequencies well down into the audio range

Definitions

  • This invention relates to a rotary coupling for transferring electrical energy between two members arranged for rotation relative to each other. More particularly, it relates to a broadband rotary transformer in which the primary is the outer conductor of a substantially coaxial system having the transformer secondary as its inner conductor. This configuration greatly reduces the leakage inductance, thereby materially extending the bandwidth limit of operation.
  • Rotary couplings are required for the transmission of electrical energy between fixed base'members and rotating elements such as radar antennas or the like.
  • a coupling of this type may take the form of a pair of'abutting circular waveguide sections with a rotary joint between them.
  • the energy to be transferred through the coupling includes relatively low frequency components a waveguide is impractical because of the size required. Therefore, two other types of coupling have been used.
  • One of these is a conventional slip ring arrangement comprising rings on the rotating member contacted by stationary brushes. This device is characterized by undesirable electrical noise as well as brush wear, both of which detract from serviceability, particularly where long periods of unattended operation are contemplated.
  • Rotary transformers have also been used prior to the present invention to transfer electrical energy between two relatively rotating parts.' While these transformers avoid the problems encountered with slip rings, they have exhibited another characteristic of their own. Specifically, the leakage inductance severely limits the attainable bandwidth. 7
  • Another object of the invention is to provide a rotary coupling of the above type having a low-loss characteristic.
  • a further object of the invention is to provide a coupling of the above type having a uniformly low attenuation over a broad range of frequencies.
  • Yet another object of the invention is to provide a coupling of the above type characterized by minimal generation of electrical noise.
  • FIG. 1 is an axial section of ing the invention
  • FIG. 2 is an axial section of the primary section of the coupling
  • FIG. 3 is a plan View of the face of the primary section of the coupling
  • FIG. 4 is an axial section of the secondary section of the coupling
  • FIG. 5 is a plan view of the section.
  • the present invention is embodied in a rotary transformer whose primary and secondary are in the form of loops having a common axis and mounted for rotation relative to each other about this axis.
  • the primary is constructed as a circular tube having a longitudinal slot therein; the secondary is disposed within the tube, with the secondary leads extending from the slot.
  • the primary and secondary have a combined structure similar to a coaxial cable.
  • a rotary transformer embodying the invention includes a primary section 10 and a secondary section 12 mounted for relative rotation about an axis 14.
  • the secondary sect'ion 12 is supported at the end of a stationary tube 16 and the primary section 10 is supported by set screws 17 in an outer tube 18 suitably coupled to a drive system (not shown) capable of rotating the tube 18 about the axis 14;
  • the primary section 10 includes a base 20 provided with an annular recess 22 opening toward the secondary section 12 and centered on the axis 14.
  • the recess 22 has a metallic lining which serves as a primary loop 24, i.e. the primary winding of the transformrer.
  • Primary .loop 24, which is in the form of a circular tube, has an aperture or slot 38 facing base 28 of the secondary.
  • the loop 24 is interrupted to provide ends 24a and 24b connected respectively to the outer and inner conductors of a coaxial cable 26.
  • the cable 26 extends upwardly through an aperture 27 (FIG. 2) in the base 20 for connection to a source of electrical signals (not shown).
  • the secondary section 12 includes a circular base 28 to which is secured a dielectric ring 30.
  • the ring 30, which fits within the primary loop 24, carries on its upper surface a metallic annulus serving as a secondary loop 32.
  • the loop 32 is interrupted, providing ends 32a and 32b to which the outer and inner conductors of a coaxial cable 34 are connected.
  • the cable 34 extends downwardly through an aperture 36 in the base 28 for connection to a device (not shown) receiving the signals passing through the transformer.
  • the primary and secondary sections 10 and 12 are preferably spaced from each other.
  • the dielectric ring 30 does not touch the primary a rotary coupling embodyface of the secondary loop 24, and there is a small gap, of the order of 0.005 inch between the bases and 28.
  • the primary loop 24 is in the form of a tube, except for the circular aperture or slot 38 thereof facing the base 28 (FIG. 1), almost all of the magnetic field associated with current conducted by this loop is outside the loop. Thus, almost the entire magnetic field links the secondary loop 32. Even the portion of this field which is within the interior of the loop 24 because of fringing effects largely links the secondary loop 32 because of the distance from the aperture 38 to the loop 32. Accordingly, the leakage inductance of the transformer is very small, and this materially extends the high frequency range of the coupling.
  • the bases 20 and 28 are preferably made of ferrite so as to provide a low reluctance path for magnetic fields in the desired regions surrounding the primary loop 24. This is particularly helpful in maintaining a high coupling coefficient at the lower frequency end of the operating range.
  • the coupling coefficient of the transformer is relatively independent of the angular position of the primary with respect to the secondary as long as the circumference of the primary and secondary loops is substantially shorter than a wavelength at the frequencies of the signals to be transferred by the coupling.
  • the transformer may be provided with a step-up ratio by providing the secondary loop 32 with a plurality of turns instead of the single turn in the illustrated embodiment of the invention,
  • the slot 38 need not face in the axial direction as shown in the drawings. It may face radially outward or inward from the primary loop 24, although the illustrated configuration provides for easier fabrication of the transformer.
  • a rotary transformer comprising (A) a substantially circular single turn primary conductor having (1) a tubular cross-section, and (2) a longitudinal slot,
  • (C) means for mounting said primary and secondary conductors for continuous relative rotation about the axis of the circle defined by said primary conductor.
  • a rotary transformer comprising (A) a single turn primary in the form of a tubular first conductor (1) whose axis describes a first circle, and 2) having a longitudinal slot therein, (B) a single turn secondary in the form of a second conductor (1) disposed within said primary conductor, and (2) describing a circle substantially concentric with said first circle,
  • (D) means mounting said primary and secondary for relative rotation about the center of said circles.
  • a rotary transformer comprising (A) first and second base members of high permeability magnetic. material,
  • (B) means forming a circular recess in said first base member opening toward said second base member
  • (G) means mounting said first and second base members for relative rotation thereof about the center of said first and second circles.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Multimedia (AREA)
  • Recording Or Reproducing By Magnetic Means (AREA)
  • Water Treatment By Electricity Or Magnetism (AREA)
  • Apparatus For Radiation Diagnosis (AREA)
  • Waveguide Connection Structure (AREA)
US450980A 1965-04-26 1965-04-26 Broadband rotary transformer Expired - Lifetime US3348181A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US450980A US3348181A (en) 1965-04-26 1965-04-26 Broadband rotary transformer
GB15948/66A GB1111464A (en) 1965-04-26 1966-04-12 Broadband rotary transformer
DE19661563330 DE1563330A1 (de) 1965-04-26 1966-04-16 Drehtransformator
NL6605587A NL6605587A (forum.php) 1965-04-26 1966-04-26

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US450980A US3348181A (en) 1965-04-26 1965-04-26 Broadband rotary transformer

Publications (1)

Publication Number Publication Date
US3348181A true US3348181A (en) 1967-10-17

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Family Applications (1)

Application Number Title Priority Date Filing Date
US450980A Expired - Lifetime US3348181A (en) 1965-04-26 1965-04-26 Broadband rotary transformer

Country Status (4)

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US (1) US3348181A (forum.php)
DE (1) DE1563330A1 (forum.php)
GB (1) GB1111464A (forum.php)
NL (1) NL6605587A (forum.php)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3531748A (en) * 1968-10-23 1970-09-29 Himmelstein & Co S Rotary transformer construction
US3531749A (en) * 1969-03-27 1970-09-29 Himmelstein & Co S Rotor structure
US3611230A (en) * 1970-11-23 1971-10-05 Lebow Associates Inc Rotary transformer structure
US3921114A (en) * 1972-11-30 1975-11-18 Eastern Electronics Norwich Transformer with relatively movable sections
US4060799A (en) * 1974-09-05 1977-11-29 Control Systems Research, Inc. Two-speed resolver employing differential reduction techniques
US5864223A (en) * 1996-11-05 1999-01-26 Meyer; Dennis R. Battery life extender apparatus
US5969507A (en) * 1998-04-06 1999-10-19 Meyer; Dennis R. Battery life extender apparatus
US6101084A (en) * 1997-02-12 2000-08-08 Rakov; Mikhail A. Capacitive rotary coupling
US7068015B1 (en) * 1999-10-07 2006-06-27 Vestas Wind Systems A/S Wind power plant having magnetic field adjustment according to rotation speed

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US428618A (en) * 1890-05-27 Transformer for heavy currents
DE515865C (de) * 1931-01-15 Siemens & Halske Akt Ges Transformator mit in einem Eisenmantel eingeschlossenen Wicklungen fuer elektroakustische Zwecke
US2894231A (en) * 1953-12-01 1959-07-07 Maxwell R Krasno Signal coupling device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US428618A (en) * 1890-05-27 Transformer for heavy currents
DE515865C (de) * 1931-01-15 Siemens & Halske Akt Ges Transformator mit in einem Eisenmantel eingeschlossenen Wicklungen fuer elektroakustische Zwecke
US2894231A (en) * 1953-12-01 1959-07-07 Maxwell R Krasno Signal coupling device

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3531748A (en) * 1968-10-23 1970-09-29 Himmelstein & Co S Rotary transformer construction
US3531749A (en) * 1969-03-27 1970-09-29 Himmelstein & Co S Rotor structure
US3611230A (en) * 1970-11-23 1971-10-05 Lebow Associates Inc Rotary transformer structure
US3921114A (en) * 1972-11-30 1975-11-18 Eastern Electronics Norwich Transformer with relatively movable sections
US4060799A (en) * 1974-09-05 1977-11-29 Control Systems Research, Inc. Two-speed resolver employing differential reduction techniques
US5864223A (en) * 1996-11-05 1999-01-26 Meyer; Dennis R. Battery life extender apparatus
US6101084A (en) * 1997-02-12 2000-08-08 Rakov; Mikhail A. Capacitive rotary coupling
US5969507A (en) * 1998-04-06 1999-10-19 Meyer; Dennis R. Battery life extender apparatus
US7068015B1 (en) * 1999-10-07 2006-06-27 Vestas Wind Systems A/S Wind power plant having magnetic field adjustment according to rotation speed

Also Published As

Publication number Publication date
GB1111464A (en) 1968-04-24
NL6605587A (forum.php) 1966-10-27
DE1563330A1 (de) 1970-01-29

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