US2999218A

US2999218A - Coaxial rotary joint

Info

Publication number: US2999218A
Application number: US862731A
Authority: US
Inventors: William J Moulds
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-12-29
Filing date: 1959-12-29
Publication date: 1961-09-05
Anticipated expiration: 1978-09-05

Description

p 1961 w. J. MOULDS 2,999,218

COAXIAL ROTARY JOINT Filed Dec. 29, 1959 2,999,218 CDAXIAL RQTARY JOINT William J. Moulds, Albuquerque, N. Mere, assignor to the United States of America as represented by the Secretary of the Air Force Filed Dec. 29, 1959, Ser. No. 362,731 1 Claim. (Cl. 339-8) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the United States Government for governmental purposes without payment to me of any royalty thereon.

This invention relates to a coaxial rotary joint for obtaining data from a rotating system for application to a stationary system or device such as an oscilloscope.

One object of the invention is to provide a rotary joint with low attenuation and low noise generation within the range of from 0 to 250 rpm.

This and other objects will be more clearly understood from the following detailed description taken with the drawing, wherein:

FIG. 1 shows a front elevational view partially in section of a rotary joint according to the invention.

PEG. 2 shows a full sectional view of the device of FIG. 1 along the line 2-2.

FIG. 3 shows a full sectional view of the device of HG. 1 along the line 33.

Referring more particularly to FIG. 1 of the drawing which shows a rotary joint having a movable assembly 11 and a stationary assembly 12.

The stationary assembly consists of an upper cylindrical housing 13, with a polished inner surface, a lower housing 14, an upper plate member 15, a lower plate member 16, an upper bearing 17 and a lower bearing 18.

The upper housing 13 has four studs 20, two of which are shown in this figure extending out of the upper end thereof and four studs 21, three of which are shown, extending out of the lower end. The upper bear-ing 17 and upper plate member 15 are secured by means of nuts 22 and the lower bearing 18, the lower housing 14 and the lower plate member 16 are secured by means of nuts 23. in the device built the upper and lower housings, the upper and lower plate members and studs were made of brass and the upper and lower bearings were made of Teflon, but it is obvious that other materials could be used if desired.

The rotating assembly consists of a connector member, having an inner conductor 26 and an outer conductor 27 which are separated by means of an insulator 28.

The connector member rotates together with the apparatus to which it is attached at 19 within bearings 17 and 1-8 and is held in place by means of flange 29 and shoulder 30. The outer conductor of the rotor assembly is connected to the outer conductor of a cable 31 by means of a pair of wipers 32 made of beryllium copper springs 33 with silvered contact buttons 34. The buttons 34 wipe against the polished inner surface of the upper housing member 13 which is connected to the outer conductor of cable 31 through brass stud bolts 21, the lower plate member 16 and flange 24. The wipers are attached to the outer conductor 27 by means of screws 35.

The inner conductor 26 is connected to the inner conductor of cable 31 by means of a pair of wipers 40 made of the same material as wipers 32 which wipe against the polished surface of a copper disk 42. The disk 42 is connected to the inner conductor 26 at 43. A Teflon ring 44 fits over outer conductor 27 and has a brass ring 45 fitted around the end thereof adjacent disk 42. Disk 42 is silver soldered to ring 45 to add support for disk 42. The space between outer conductor 27 and disk 42 should be great enough to prevent a short. For device shown the spacing is .031 inch. A static brush mount 46 is secured to the lower plate member 16 as shown in FIG. 3.

The springs 47 for wipers 40 are attached to brush mount 4d by means of screw 43 as shown in FIG. 3; The inner conductor of cable 31 is connected to springs 47 at this point.

The device has been tested for a frequency range from DC. to 20 MC. while rotating up to 400 rpm. with less than 0.5 millivolt of noise generation. The device has also been tested with 0.1 microsecond pulses and found to be satisfactory.

There is thus provided a coaxial rotary joint with low attenuation and low noise generation.

While certain specific embodiments have been described in some detail, it is obvious that numerous changes can be made without departing from the general principles and scope of the invention.

I claim:

A joint for connecting a rotating coaxial system to a stationary coaxial system comprising; a cylindrical electrically conductive housing having a portion of the inner surface polished, a first electrically conductive plate member attached to one end of the housing, a second plate member attached to the other end of the housing, means for connecting the housing to the outer conductor of the stationary coaxial system through the first plate, a first bearing member located within the housing and spaced between the first and second plates, a second bearing member located within the housing and adjacent to the second plate, a coaxial connector member rotatable and supported within said bearings, the coaxial connector member having an inner conductor member and an outer conductor member insulated from one another, the outer conductor member adapted to be connected to the outer conductor of the rotating coaxial system and the inner conductor member adapted to be connected to the inner conductor of the rotating coaxial system; a plurality of spring Wiper elements connected to and rotatable with the outer conductor of the coaxial connector member, each of the wiper members having a contact button, the contact buttons engaging the polished inner surface of the housing during rotation of the connector member; an electrically conductive disk connected to and rotatable with the inner conductor of the connector member and spaced from the outer conductor, one surface of the disk being polished, an insulating wiper mount mounted in the housing adjacent the first plate, a plurality of stationary spring wipers having contact buttons mounted in the hous ing on the wiper mount, the contact buttons of the stationary wipers engaging the polished surface of the disk during rotation of the disk and means for connecting the stationary wiper elements with the inner conductor of the stationary coaxial system.

References Cited in the file of this patent UNITED STATES PATENTS 1,657,306 Gursky Ian. '24, 1928 1,925,095 Halliburton Sept. 5, 1933 2,190,295 Miller et a1 Feb. 13, 1940 2,473,526 Hood et a1. June 21, 1949 FOREIGN PATENTS 89,032 Switzerland Apr. 16, 1921