Self-contained propulser with two-degree-of-freedom actuation

Abstract

An invention disclosed herein pertains to a thruster suitable for underwater vehicles. Such a thruster includes a steerable duct and propeller. The thruster motor, the two directional servo motors and all necessary electronics are contained in a single fluid filled and pressure compensated container. This is made possible, by a compact steering mechanism that allows the propeller and duct to be steered about the pitch and yaw axis of the vehicle and a spherical rolling seal which allows the fluid in the thruster to be maintained at a pressure of 2-5 psig. A gimbal that features a ring drive element enables efficient use of space. An actuation to drive the thruster may fit inside the ring drive element.

1 . A seal member comprising a flexible membrane comprising a substantially symmetrical section of a spherical surface.  
   
   
       2 . The seal member of  claim 1 , the section of a spherical surface comprising an inner end having an inner radius, coupled by a skirt to an outer end, having an outer radius that is larger than the inner radius.  
   
   
       3 . The seal member of  claim 2 , at least one of the inner and outer ends of the seal member comprising a bead.  
   
   
       4 . The seal member of  claim 1 , the flexible membrane consisting essentially of a material selected from the group of urethane and silicone.  
   
   
       5 . The seal member of  claim 1 , the flexible membrane comprising an extent between the inner and outer end of a spherical arc of slightly more then one half the maximum deflection of a joint in which the seal member seals.  
   
   
       6 . The seal member of  claim 1 , the membrane having a flexibility and thickness such that the membrane is foldable upon itself so as to align the inner and the outer ends to be concentric with each other.  
   
   
       7 . The seal member of  claim 1 , further comprising: 
 a. an inner housing member, having an outer edge, sized to couple with the inner end of the spherical section; and    b. an outer housing member, having an inner edge sized to couple with the outer end of the spherical section.    
   
   
       8 . The seal member of  claim 1 , the membrane having a strength capable of maintaining a seal against a relative pressure across it of between one and five pounds per square inch.  
   
   
       9 . The seal member of  claim 7 , further having a flexibility such that, starting from a 0° position in which the inner and outer ends of the seal are concentric, the outer end is rotatable, relative to the inner end, around two orthogonal axes that are coincident in the 0° position with diameters of both ends of the seal member.  
   
   
       10 . The seal member of  claim 9 , the two orthogonal axes comprising yaw and pitch axes of a vehicle, of which the housing members are a component.  
   
   
       11 . A vessel comprising: 
 a. an outer housing member having a spherical inner surface;    b. an inner housing member having a spherical outer surface, located with the outer surface of the inner housing member concentric with, spaced from, and inside the inner surface of the outer housing member; and    c. spanning from the inner surface of the outer housing member to the outer surface of the inner housing member, a flexible seal member comprising a membrane that is a substantially symmetrical section of a spherical surface.    
   
   
       12 . The vessel of  claim 11 , further wherein the section of a spherical surface of the seal comprises an inner end having an inner circumference, coupled by a skirt to an outer end, having an outer circumference that is stretched to be larger than the inner circumference.  
   
   
       13 . The vessel of  claim 11 , the inner end of the spherical surface of the seal member being coupled to the inner housing member and the outer end of the spherical surface of the seal member being coupled to the outer housing member, and the skirt being folded.  
   
   
       14 . A vessel comprising: 
 a. an inner housing having a first portion;    b. an outer housing having a first portion, concentric with and at least in part surrounding the first portion of the inner housing; and    c. coupled to both the inner and the outer housings, a spherical section rollable seal member.    
   
   
       15 . The vessel of  claim 14 , the first portion of the inner housing comprising a section of a sphere having a center and an inner housing circumference, and the first portion of the outer housing comprising a section of a sphere having a center and an outer housing circumference, that is larger than the inner housing circumference.  
   
   
       16 . The vessel of  claim 15 , the seal being coupled to the inner housing at an inner end and to the outer housing at an outer end.  
   
   
       17 . The vessel of  claim 16 , the seal arranged relative to the inner and outer housings such that in a 0° position, the seal member is folded, such that the inner and outer ends of the seal member are substantially adjacent each other.  
   
   
       18 . The vessel of  claim 16 , the folded seal member defining a concave surface and a convex surface at its fold, the concave surface being closer to the inner and outer ends of the seal member than is the convex surface, when the seal member is in a 0° position.  
   
   
       19 . The vessel of  claim 14 , the inner and outer housings and seal member being arranged such that rotation of the inner housing relative to the outer housing about a first axis that passes through: 
 a. the center of the section of the sphere of the spherical portion of the inner housing;    b. the center of the section of the sphere of the spherical portion of the outer housing; and    c. the seal equator;    causes the seal to roll along itself so that an extent of a different region of overlap of the seal member changes.    
   
   
       20 . The vessel of  claim 19 , the inner and outer housings and seal member being arranged such that rotation of the inner housing relative to the outer housing about a second axis, that is perpendicular to the first axis and that passes through: 
 a. the center of the section of the sphere of the spherical portion of the inner housing;    b. the center of the section of the sphere of the spherical portion of the outer housing; and    c. the seal equator;    causes the seal to roll along itself so that a different extent of a region of overlap of the seal member changes.    
   
   
       21 . The vessel of  claim 20 , the inner and outer housings and seal member being arranged such that the inner housing is rotatable relative to the outer housing simultaneously about both the first and second axes without disrupting sealing integrity of the seal.  
   
   
       22 . The vessel of  claim 14 , there being a region inside the vessel adjacent the concave surface of the sealing member that is pressureizeable to a relatively higher pressure than a region adjacent the convex surface of the sealing member.  
   
   
       23 . The vessel of  claim 22 , further comprising a pressure compensator that couples the relatively higher pressure region of the vessel to an ambient environment outside of the vessel, such that pressure in the higher pressure region exceeds that of the ambient environment.  
   
   
       24 . The vessel of  claim 14 , further comprising a pressure compensator that hydraulically couples a relatively higher pressure region of the vessel to an ambient environment outside of the vessel, such that pressure in the higher pressure region exceeds that of the ambient environment by an amount within a set range, and further comprising, within the higher pressure compensated region: 
 a. a first actuator that is coupled to the inner housing;    b. a second actuator that is coupled to the inner housing;    c. electronic components that provide inputs to the first and second actuators.    
   
   
       25 . The vessel of  claim 24 , the first actuator comprising a servo-motor.  
   
   
       26 . The vessel of  claim 24 , the first and second actuators being coupled to a gimbal assembly that is movable with respect to a first and a second degree of freedom.  
   
   
       27 . The vessel of  claim 26 , the first actuator being coupled to the gimbal assembly to actuate motion of the inner housing with respect to the first degree of freedom.  
   
   
       28 . The vessel of  claim 26 , the second actuator being coupled to the gimbal assembly to actuate motion of the inner housing with respect to the second degree of freedom.  
   
   
       29 . The vessel of  claim 26 , the first and second actuators being coupled to the gimbal assembly to independently actuate motion of the inner housing with respect the first and second degrees of freedom.  
   
   
       30 - 47 . (canceled)