Title of Invention	A HIGH FREQUENCY SLIPRING WITH EMBEDDED BEARINGS FOR RADARS
Abstract	A high frequency slipring with embedded bearings for radars, such as doplar weather radar which provides self and independent rotation of high speed. The slipring comprises a conductor ring surrounded by an inner and an outer insulation rings which are housed between an inner and an outer casings. The conductor ring, said inner insulation ring and said inner casing are attached together forming an inner part. A top cover plate and a bottom cover plate are fixed to said inner casing by fixing means. A first embedded bearing is located between the outer casing and the top cover plate and a second embedded bearing is located between the outer casing and the bottom cover plate to provide relative movement between the conductor ring and the outer casing. At least one inner connector and one outer connector are provided for external connections.

Title of Invention

A HIGH FREQUENCY SLIPRING WITH EMBEDDED BEARINGS FOR RADARS

Abstract

A high frequency slipring with embedded bearings for radars, such as doplar weather radar which provides self and independent rotation of high speed. The slipring comprises a conductor ring surrounded by an inner and an outer insulation rings which are housed between an inner and an outer casings. The conductor ring, said inner insulation ring and said inner casing are attached together forming an inner part. A top cover plate and a bottom cover plate are fixed to said inner casing by fixing means. A first embedded bearing is located between the outer casing and the top cover plate and a second embedded bearing is located between the outer casing and the bottom cover plate to provide relative movement between the conductor ring and the outer casing. At least one inner connector and one outer connector are provided for external connections.

Full Text	The present invention relates to a high frequency slipring with embedded bearings for radars such as doplar weather radar. Sliprings are electromechanical devices used in radars. Various types of sliprings are known in the art. A slipring is a critical subsystem to interface electrical power and signal circuitry between stationary and rotating parts of a radar system. Electrical information representing various parameters are transferred from a rotary or rotating tables to stationary control panels without any loss or deviation of data with the help of precision sliprings, Sliprings which can be operated with high frequency video circuits are used in radars for data transfer, and as substitute of rotary joint in certain cases. In one type of conventional slipring, concentric conductor rings are embedded in glass epoxy providing insulation between the conductor rings. The main drawback of this type of sliprings are that the glass epoxy insulator is hygroscopic and hence soaks in water. This brings down the insulation of the glass epoxy insulator to below 20 Megohm instead of the specified 1000 Megohm when 500 volt DC is applied. Indian patent application 544/MAS/99 describes a precision slipring which has improved water resistance. The * epoxy compound used for embedding the conductor rings is non hygroscopic. This slipring is capable of transferring electrical signals from kilovolts to 440 volts at a frequency range of 50Hz to 50MHz. This slipring comprises a plurality of co-planner concentric conductor rings supported by an inner support member and embedded in at least one side of an insulator disc made of molded epoxy resin. Two movable contacts are provided from opposite sides of each conductor ring. The following disadvantages are experienced with this type of slip ring. 1. The inter-distance of the conductor rings has to be increased for increasing the operation frequency level. 2, The conductor rings may pick up signals from the adjacent conductor ring resulting in cross talk 3. Dirt and environment can affect the slipring and its performance as it is open to atmosphere. 4, The slipring cannot work independently as it has no bearings. It has to be installed in a rotating shaft so that the contact brush can be made to slide on the conductor ring. The object of the present invention is to provide a high frequency slipring with embedded bearings which avoids or minimizes the above mentioned disadvantages. Accordingly the present invention provides a high frequency slipring with embedded bearings for radars such as doplar weather radar, comprising a conductor ring surrounded by an inner insulation ring and an outer insulation ring; an inner casing and an outer casing housing said insulation rings and said conductor ring; the said conductor ring and the inner insulation ring being attached to the inner casing; a top cover plate and a bottom cover plate being fixed to said inner casing by fixing means; a first embedded bearing located between the outer casing and the top cover plate; a second embedded bearing located between the outer casing and the bottom cover plate, the said embedded bearings providing relative movement between the conductor ring and the outer casing; and at least one inner connector and one outer connector for external connections. The sliprings according to the present invention provides self and independent rotation of high speed, greater than the regular rotary shaft, The two self embedded slim bearings' along the cover plates of the slipring provides free rotation of high speech upto 300 rpm. This type of sliprings are used in video tracking, data transfer etc. for which the frequencies upto 30 to 40 MHz is required. The conventional disk type or coplanar type sliprings have to go with other conventional circuits on the assembly while the bearing embedded slipring of the present invention is independent and self operative at different speeds as required. The other advantage is that the shielding is also better due to their metallic bearings with good contacts on either side of the circuits. The sliprings of the present invention is used in star tracking radars, observatories, weather and cyclone warning radars^ surveillance radars etc. in which video data is also necessary. The invention will now be described, by way of example only, with reference to the accompanying drawings, in which : Fig. 1 is a plan view of a slipring according to the invention. Fig, 2 is a cross sectional view along A^A of figure 1, Fig. 3 is an enlarged view of the portion indicated as B in fig. 2. The conductor ring (7) which is preferably made of silver alloy (coin silver) is surrounded by inner insulation ring (3) and an outer insulation ring (4), An inner casing (1) and an outer casing (2) are placed in such a way to house the conductor ring (7) and the inner and outer insulating rings (3,4). The insulation rings may be made of teflon or modified epoxy. The whole arrangement is covered by a top cover plate (5) and a bottom cover plate (6). The top cover plate (5) and the bottom cover plate (6) are fixed to the inner casing (1) by fixing means (13), such as a screw. The said casings (1,2) and the said cover plates (5,6) are preferably made of brass. A first embedded bearing (8) is located between the top cover plate (5) and the outer casing (2). A second embedded bearing (9) is located between the bottom cover plate (6) and the outer casing (2). The said bearings (8,9) are preferably ball bear ings having a plurality of balls. At least one inner connector (12) and one outer connector (11) are provided for external connection. In use, one connector is kept stationary and the other connector is moved around the conductor ring. The said outer connector (11) has a contact (10) preferably in the form of a brush made of silver which slides on the conductor ring (7). The outer casing (2) may be provided with locking means to prevent the outer part of the slipring from rotating while the inner part is rotated. The slipring according to the inventions can have a size from 100mm diameter to 35Gmm diameter with a thickness varying upto 40mm. The slipring according to the invention is capable of independent rotation on its own bearings and hence it can also be used without a separate rotary shaft with bearing assembly. There are ample number of contacts for shield with the outer shell. The entire circuit is placed in a shielded box and hence pickup from the next circuit is avoided. Each circuit can be isolated using epoxy isolators in between and thereby cross-talk can be reduced. The frequency level can be changed by adjusting the length of the stub used, thereby the VHP capacity is increased or decreased* It is possible to obtain VSWR in the range of 1,65 to 1,3 which is better than the existing sliprings. The slipring according to the invention can be replaced and maintained easily, since it is separate and not assembled with the main bulk system. Further, the slipring according to the invention can be made to have any diameter irrespective of the other sliprings. Hence, the size reduction or enlargement is possible for the VHP circuits alone or with the other parts. This saves the fabrication cost and time. The slipring according to the invention can be made without using the moulding technique* It is used in star tracking radars, video circuits in weather warning radars etc. This type of slipring can be made to adapt any frequency level from lOMHz; to even lOOMHz by changing the insulator and capacitance. WE CLAIM : 1. A high frequency slipping with embedded bearings for radars such as doplar weather radar, comprising a conductor ring (7) surrounded by an inner insulation ring (3) and an outer insulation ring (4); an inner casing (1) and an outer casing (2) housing said insulation rings (3,4) and said conductor ring (7); the said conductor ring (7) and the inner insulation ring (3) being attached to the inner casing (1); a top cover plate (5) and a bottom cover plate (6) being fixed to said inner casing (1) by fixing means (13); a first embedded bearing (8) located between the outer casing (2) and the top cover plate (5); a second embedded bearing (9) located between the outer casing (2) and the bottom cover plate (6), the said embedded bearings (8,9) providing relative movement between the conductor ring (7) and the outer casing (2); and at least one inner connector (12) and one outer connector (11) for external connections. 2. The slipring as claimed in claim 1, wherein the said bearings (8,9) are ball bearings having plurality of balls, 3. The slipring as claimed in claim 1, wherein the inner and the outer casings (1,2) are made of brass. 4. The slipring as claimed in claim 1, wherein the conductor ring (7) is made of silver alloy. 5. The slipring as claimed in claim 1, wherein the inner and the outer insulation rings (3,4) are made of teflon or modified epoxy. 6. The slipring as claimed in claim 1 wherein the outer casing (2) is provided with locking means for self locking while the inner casing (1) is rotated. 7. A high frequency slipring with embedded bearings for radars substantially as hereinbefore described with reference to the accompanying drawings.

Full Text

The present invention relates to a high frequency

slipring with embedded bearings for radars such as doplar weather radar.
Sliprings are electromechanical devices used in radars. Various types of sliprings are known in the art. A slipring is a critical subsystem to interface electrical power and signal circuitry between stationary and rotating parts of a radar system. Electrical information representing various parameters are transferred from a rotary or rotating tables to stationary control panels without any loss or deviation of data with the help of precision sliprings, Sliprings which can be operated with high frequency video circuits are used in radars for data transfer, and as substitute of rotary joint in certain cases.
In one type of conventional slipring, concentric conductor rings are embedded in glass epoxy providing insulation between the conductor rings. The main drawback of this type of sliprings are that the glass epoxy insulator is hygroscopic and hence soaks in water. This brings down the insulation of the glass epoxy insulator to below 20 Megohm instead of the specified 1000 Megohm when 500 volt DC is applied.
Indian patent application 544/MAS/99 describes a

precision slipring which has improved water resistance. The
*
epoxy compound used for embedding the conductor rings is non hygroscopic. This slipring is capable of transferring electrical signals from kilovolts to 440 volts at a frequency range of 50Hz to 50MHz. This slipring comprises a plurality of co-planner concentric conductor rings supported by an inner support member and embedded in at least one side of an insulator disc made of molded epoxy resin. Two movable contacts are provided from opposite sides of each conductor ring. The following disadvantages are experienced with this type of slip ring.
1. The inter-distance of the conductor rings has to be
increased for increasing the operation frequency level.
2, The conductor rings may pick up signals from the
adjacent conductor ring resulting in cross talk
3. Dirt and environment can affect the slipring and
its performance as it is open to atmosphere.
4, The slipring cannot work independently as it has no
bearings. It has to be installed in a rotating shaft so that the
contact brush can be made to slide on the conductor ring.
The object of the present invention is to provide a high frequency slipring with embedded bearings which avoids or minimizes the above mentioned disadvantages.

Accordingly the present invention provides a high frequency slipring with embedded bearings for radars such as doplar weather radar, comprising a conductor ring surrounded by an inner insulation ring and an outer insulation ring; an inner casing and an outer casing housing said insulation rings and said conductor ring; the said conductor ring and the inner insulation ring being attached to the inner casing; a top cover plate and a bottom cover plate being fixed to said inner casing by fixing means; a first embedded bearing located between the outer casing and the top cover plate; a second embedded bearing located between the outer casing and the bottom cover plate, the said embedded bearings providing relative movement between the conductor ring and the outer casing; and at least one inner connector and one outer connector for external connections.
The sliprings according to the present invention provides self and independent rotation of high speed, greater than the regular rotary shaft, The two self embedded slim bearings' along the cover plates of the slipring provides free rotation of high speech upto 300 rpm. This type of sliprings are used in video tracking, data transfer etc. for which the frequencies upto 30 to 40 MHz is required. The conventional disk type or coplanar type sliprings have to go with other conventional circuits on the assembly while the bearing embedded

slipring of the present invention is independent and self operative at different speeds as required. The other advantage is that the shielding is also better due to their metallic bearings with good contacts on either side of the circuits.
The sliprings of the present invention is used in star
tracking radars, observatories, weather and cyclone warning
radars^ surveillance radars etc. in which video data is also
necessary.
The invention will now be described, by way of example only, with reference to the accompanying drawings, in which :
Fig. 1 is a plan view of a slipring according to the
invention.
Fig, 2 is a cross sectional view along A^A of figure 1, Fig. 3 is an enlarged view of the portion indicated as
B in fig. 2.
The conductor ring (7) which is preferably made of silver alloy (coin silver) is surrounded by inner insulation ring (3) and an outer insulation ring (4), An inner casing (1) and an outer casing (2) are placed in such a way to house the conductor ring (7) and the inner and outer insulating rings (3,4). The insulation rings may be made of teflon or modified epoxy. The

whole arrangement is covered by a top cover plate (5) and a bottom cover plate (6). The top cover plate (5) and the bottom cover plate (6) are fixed to the inner casing (1) by fixing means (13), such as a screw. The said casings (1,2) and the said cover plates (5,6) are preferably made of brass. A first embedded bearing (8) is located between the top cover plate (5) and the outer casing (2). A second embedded bearing (9) is located between the bottom cover plate (6) and the outer casing (2). The said bearings (8,9) are preferably ball bear ings having a plurality of balls. At least one inner connector (12) and one outer connector (11) are provided for external connection. In use, one connector is kept stationary and the other connector is moved around the conductor ring. The said outer connector (11) has a contact (10) preferably in the form of a brush made of silver which slides on the conductor ring (7). The outer casing (2) may be provided with locking means to prevent the outer part of the slipring from rotating while the inner part is rotated.
The slipring according to the inventions can have a size from 100mm diameter to 35Gmm diameter with a thickness varying upto 40mm.
The slipring according to the invention is capable of independent rotation on its own bearings and hence it can also be

used without a separate rotary shaft with bearing assembly. There are ample number of contacts for shield with the outer shell. The entire circuit is placed in a shielded box and hence pickup from the next circuit is avoided. Each circuit can be isolated using epoxy isolators in between and thereby cross-talk can be reduced. The frequency level can be changed by adjusting the length of the stub used, thereby the VHP capacity is increased or decreased* It is possible to obtain VSWR in the range of 1,65 to 1,3 which is better than the existing sliprings.
The slipring according to the invention can be replaced and maintained easily, since it is separate and not assembled with the main bulk system. Further, the slipring according to the invention can be made to have any diameter irrespective of the other sliprings. Hence, the size reduction or enlargement is possible for the VHP circuits alone or with the other parts. This saves the fabrication cost and time.
The slipring according to the invention can be made without using the moulding technique* It is used in star tracking radars, video circuits in weather warning radars etc.
This type of slipring can be made to adapt any frequency level from lOMHz; to even lOOMHz by changing the insulator and capacitance.

WE CLAIM :
1. A high frequency slipping with embedded bearings for radars such as doplar weather radar, comprising a conductor ring (7) surrounded by an inner insulation ring (3) and an outer insulation ring (4); an inner casing (1) and an outer casing (2) housing said insulation rings (3,4) and said conductor ring (7); the said conductor ring (7) and the inner insulation ring (3) being attached to the inner casing (1); a top cover plate (5) and a bottom cover plate (6) being fixed to said inner casing (1) by fixing means (13); a first embedded bearing (8) located between the outer casing (2) and the top cover plate (5); a second embedded bearing (9) located between the outer casing (2) and the bottom cover plate (6), the said embedded bearings (8,9) providing relative movement between the conductor ring (7) and the outer casing (2); and at least one inner connector (12) and one outer connector (11) for external connections.
2. The slipring as claimed in claim 1, wherein the said bearings (8,9) are ball bearings having plurality of balls,
3. The slipring as claimed in claim 1, wherein the inner and the outer casings (1,2) are made of brass.

4. The slipring as claimed in claim 1, wherein the
conductor ring (7) is made of silver alloy.
5. The slipring as claimed in claim 1, wherein the inner
and the outer insulation rings (3,4) are made of teflon or
modified epoxy.
6. The slipring as claimed in claim 1 wherein the outer
casing (2) is provided with locking means for self locking while
the inner casing (1) is rotated.
7. A high frequency slipring with embedded bearings for
radars substantially as hereinbefore described with reference to
the accompanying drawings.

Documents:

028-mas-2000-abstract.pdf

028-mas-2000-claims filed.pdf

028-mas-2000-claims granted.pdf

028-mas-2000-correspondnece-others.pdf

028-mas-2000-correspondnece-po.pdf

028-mas-2000-description(complete)filed.pdf

028-mas-2000-description(complete)granted.pdf

028-mas-2000-drawings.pdf

028-mas-2000-form 1.pdf

028-mas-2000-form 19.pdf

028-mas-2000-form 26.pdf

028-mas-2000-form 3.pdf

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Patent Number

213925

Indian Patent Application Number

28/MAS/2000

PG Journal Number

13/2008

Publication Date

31-Mar-2008

Grant Date

23-Jan-2008

Date of Filing

12-Jan-2000

Name of Patentee

INDIAN SPACE RESEARCH ORGANISATION

Applicant Address

ISRO HEADQUARTERS DEPARTMENT OF SPACE, ANTHARIKSH BHAVAN, NEW BEL ROAD, BANGALORE 560 094,

Inventors:

#	Inventor's Name	Inventor's Address
1	KARUNAKARAN RAJAPPA KAIMAL	VIKRAM SARABHAI SPACE CENTRE, THIRUVANANTHAPURAM - 695 022,
2	VALIAVALAPPIL KARUNAKARAN	VIKRAM SARABHAI SPACE CENTRE, THIRUVANANTHAPURAM - 695 022,
3	VETTITHUVUTHIL CHELLAPPAN VIJAYAKUMAR	VIKRAM SARABHAI SPACE CENTRE, THIRUVANANTHAPURAM - 695 022,
4	KAMAPALAN RAVINDRAN	VIKRAM SARABHAI SPACE CENTRE, THIRUVANANTHAPURAM - 695 022,

PCT International Classification Number

G0 1 S 7/12

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA