Sealed rotary joint for turret rotator

• US 20060033288A1
• Filed: 08/10/2004
• Published: 02/16/2006
• Est. Priority Date: 08/10/2004
• Status: Active Grant

• Current Assignee: Teledyne FLIR LLC (Teledyne Technologies Incorporated)
• Original Assignee: FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Inventors: Hughes, Michael R., Sommer, Thomas M., Rosi, Ronald J.
• Granted Patent: US 7,090,178 B2
• Time in Patent Office: Days
• US Class Current: 277/412
• CPC Class Codes: F16J 15/43 kept in sealing position by magnetic force
• CPC Class Codes: F16J 15/4476 with radial path
• CPC Class Codes: F16M 11/10 around a horizontal axis F16M11/12 takes precedence
• CPC Class Codes: F16M 11/2014 around a vertical axis F16M11/2035 takes precedence

Abstract

A rotatable payload support turret for operation in a potentially hazardous environment includes a fixed element attached to a vehicle or fixed structure and a rotatable element, supported for rotation with respect to the fixed element. The turret includes a camera payload having a pointing direction configured to be upwardly pointing. An annular clearance gap formed between the fixed element and the rotatable element is sealed by a conventional gas tight magnetic fluid seal element. A wiper seal is also provided in the clearance gap between the location of the magnetic fluid and the external environment to prevent breakdown of the magnetic fluid by elements of the potentially hazardous environment. The clearance gap may also form a labyrinth seal having up to three legs that are oriented to oppose a gravitational force direction. In addition, the fixed element may include a fluid repelling feature for repelling streams of incoming fluids thereby deflecting elements of the potentially hazardous environment away from an outer opening of the clearance gap.

Claims

1. A rotary joint for operating in an environment of potentially harmful elements comprising:

a fixed element having an internal cavity formed therein and wherein one or more elements housed within the internal cavity may be damaged by said potentially harmful elements;

a rotatable element supported for rotation with respect to said fixed element;

an annular clearance gap formed between opposing surfaces of the fixed element and the rotatable element, said annular clearance gap extending from said environment of potentially harmful elements to said internal cavity;

a labyrinth seal formed between said opposing surfaces of the fixed element and the rotatable element, said labyrinth seal comprising at least one leg of the clearance gap formed to resist infiltration of said potentially harmful elements; and

,

a wiper seal positioned in the clearance gap for closing the clearance gap, said wiper seal comprising a fixed annular seal surface, attached to said fixed element, and an annular flexible seal element, attached to the rotatable element, said annular flexible seal element being forced into contact with said fixed annular seal surface by a bending force generated by an interference contact between the annular flexible seal element and the fixed annular seal surface.

2. The rotary joint of claim 1 wherein said wiper seal further comprises an annular seal wiper element captured between said annular flexible seal member and said seal surface, said annular seal wiper element comprising a layer of material having a dry lubricating, wear resistant compound incorporated therein.

3. The rotary joint of claim 2 wherein said annular seal wiper element comprises a polymetric reinforced layer of polytetrafluroroethylene, (PTFE).

4. The rotary joint of claim 1 wherein the labyrinth seal comprises at least one leg of the clearance gap oriented generally opposed to a gravitational force direction.

5. The rotary joint of claim 1 further comprising a gas tight seal attached to the fixed element and interacting with the rotating element to support a magnetic fluid in the clearance gap, said gas tight seal being positioned within the clearance gap between the internal cavity and the position within the clearance gap of the wiper seal.

6. The rotary joint of claim 1 wherein the clearance gap has an annular outer opening formed between the fixed element and the rotating element and wherein the fixed element further comprises a fluid repelling feature positioned for repelling an incoming fluid stream away from the annular outer opening.

7. The rotary joint of claim 6 wherein the fluid repelling feature comprises a radially outwardly facing annular recess formed between opposing surface of the fixed element and wherein a radially inner end of the annular recess is closed by a radius formed between said opposing surfaces.

8. The rotary joint of claim 1 wherein the clearance gap has an annular outer opening formed between the fixed element and the rotating element and wherein a surface of the fixed element forming one of the opposing surfaces for forming the clearance gap comprises a sloped surface and wherein said sloped surface is oriented to drain fluids out of the clearance gap through the annular outer opening.

9. The rotary joint of claim 1 wherein said fixed member is fixedly attached to a first support element and wherein said rotatable member comprises a second support element for supporting a sensor/emitter payload having a pointing direction and further wherein the second support element is oriented to direct the pointing direction vertically up.

10. A rotatable payload support turret for operation in a potentially hazardous environment, the support turret comprising a fixed element and a rotatable element, supported by the fixed element, for rotation with respect thereto, comprising:

a annular rotary seal attached to the fixed element in an annular clearance gap formed between said fixed element and said rotatable element, said annular rotary seal comprising a magnetic circuit formed to capture a magnetic fluid in the annular clearance gap thereby sealing the clearance gap with a gas tight seal; and

,

an annular wiper seal assembly positioned in said annular clearance gap between said potentially hazardous environment and said annular rotary seal for sealing the clearance gap to prevent elements of said potentially hazardous environment from contaminating said magnetic fluid, the annular wiper seal comprising;

an annular flexible member attached to the rotatable element for rotation therewith, and an annular sealing surface attached to said fixed element, said annular flexible member being forced into contact with said annular sealing surface during rotation of said rotatable element.

11. The rotatable payload support turret of claim 10 wherein each of said fixed element and said rotatable element are configured with opposing surfaces for forming said clearance gap there between, and further wherein said opposing surfaces are configured to form a labyrinth seal comprising at least one leg of the clearance gap formed to resist infiltration of said potentially harmful elements.

12. The rotatable payload support turret of claim 11 wherein said opposing surfaces are configured to form the labyrinth seal with three legs of the clearance gap formed to resist infiltration of said potentially harmful elements.

13. The rotatable payload support turret of claim 10 wherein the clearance gap includes an annular outer opening formed between opposing surfaces of the fixed element and the rotatable element and further wherein said fixed element is configured with a surface sloping downwardly toward said annular opening for draining potentially hazardous elements from the clearance gap.

14. The rotatable payload support turret of claim 10 wherein the clearance gap includes an annular outer opening formed between opposing surfaces of the fixed element and the rotatable element and further wherein said fixed element is configured with an annular fluid repelling feature positioned adjacent to said annular opening for repelling an incoming fluid stream away from the annular outer opening.

15. The rotatable payload support turret of claim 14 wherein the fluid repelling feature comprises an annular recess formed by opposing surfaces of the fixed element, the annular recess having an radially outward facing open end and a radially inward facing closed end, said inward facing closed end being formed by a radius between the opposing surfaces, and wherein the outward facing open end is positioned adjacent to said clearance gap annular outer opening.

16. The rotatable payload support turret of claim 10 wherein said fixed element comprises an azimuth housing having an internal cavity formed therein and wherein said rotatable element comprises a yoke for supporting the payload for rotation about an elevation axis, said yoke including a shaft extending from a bottom end thereof for mating with rotary bearings installed in the azimuth housing further comprising:

a cascade hood attached to the yoke and rotatable therewith, the cascade hood including an annular cover portion extending radially outward from the shaft and overhanging upward facing surfaces of the azimuth housing for protecting an annular clearance gap formed between the azimuth housing and the cascade hood from downwardly directed elements of the potentially hazardous environment.

17. The rotatable payload support turret of claim 16 wherein the cascade hood further comprises a first annular lip extending substantially vertically downward from a radially distal end of the annular cover portion to oppose a circumferential surface of the azimuth housing thereby forming an annular opening of the annular clearance gap.

18. The rotatable payload support turret of claim 17 wherein the cascade hood further comprises a second annular lip positioned radially inward from the first annular lip, said second annular lip having surfaces opposed to a substantially vertical surface of the azimuth housing for forming a leg of the clearance gap that is formed to resist infiltration of said potentially harmful elements.

19. The rotatable payload support turret of claim 18 wherein the azimuth housing includes a substantially upwardly extending third annular lip positioned radially between the first annular lip and the second annular lip, said third annular lip including a plurality of surfaces formed opposed to surfaces of an underside of the annular cover portion and to surfaces of said first annular lip and said second annular lip for defining the shape and dimension of the clearance gap and particularly for forming two additional legs of the clearance gap that are formed to resist infiltration of said potentially harmful elements.

20. The rotatable payload support turret of claim 18 wherein the third annular lip is formed with a plurality of drain openings passing therethrough for draining portions of the clearance gap that are radially inward of said third annular lip.

21. A method for supporting a rotatable payload support turret for operation in a potentially hazardous environment the support turret comprising a fixed element and a rotatable element supported by the fixed element for rotation with respect thereto, comprising the steps of:

magnetically capturing a magnetic fluid in the annular clearance gap thereby forming a gas tight rotary seal between the fixed element and the rotatable element; and

,

forcibly contacting an annular flexible element attached to the rotating element with a fixed annular seal ring attached to the fixed element thereby forming an annular wiper seal in the clearance gap, said wiper seal being positioned between said potentially hazardous environment and said gas tight rotary seal.

22. The method of claim 21 further comprising the step of reducing friction and wear between in the wiper seal by installing an annular wiper element between said annular flexible element and said annular seal ring, said annular wiper seal comprising a layer of material having a dry lubricating, wear resistant compound incorporated therein.

23. The method of claim 22 further comprising the step of forming said annular wiper seal element from a polymetric reinforced layer of polytetrafluroroethylene, (PTFE).

24. A wiper seal assembly for sealing an annular clearance gap formed between a fixed element and rotatable element said wiper seal assembly being attached to the rotatable element and being forced into contact with an annular seal ring attached to the fixed element, during rotation of the rotatable element, said wiper seal assembly comprising:

a annular flexible seal element having an inside diameter and a width, the annular flexible seal element further including a plurality of flexible fingers formed on a radially outer edge thereof by a plurality of evenly spaced apart slots passing through a portion of the width;

an annular seal wiper element having an inside diameter and a width each substantially matching the inside diameter and width of the annular flexible seal element, said annular seal wiper element being formed from a material having a dry lubricating, wear resistant compound incorporated therein and being mounted to the rotating element in a position between the annular flexible seal element and the annular seal ring;

an annular seal support element having an inside diameter substantially matching the inside diameter of the annular flexible seal element and a width that is less than the width of the annular flexible seal element and the annular seal wiper element, and wherein said annular seal support is mounted to the rotatable element in a position between the annular flexible seal element and a mounting surface of the rotatable element; and

,

wherein each of the annular flexible seal element, the annular seal wiper and the annular seal support includes a plurality of mounting holes formed therein for mounting the seal assembly to the rotatable element to support the radially distal ends of the annular flexible seal element and the annular wiper seal element cantilevered into the clearance gap and forced into contact with the seal ring.

25. A wiper seal assembly according to claim 24 wherein each of said annular flexible seal element and said annular seal support element is formed from a material comprising a composite of layers of epoxy reinforced fiberglass.

26. A wiper seal assembly according to claim 24 wherein said annular seal wiper element is formed from a polymetric reinforced layer of PTFE.