Flow guide

Abstract

A flow guide directs a fluid flow across a surface of a device, for example a lens surface of an endoscope, in a controlled manner to facilitate flow attachment to the surface. Embodiments include features that impart a non-uniform velocity profile and/or include guide surfaces for facilitating flow attachment and/or coverage.

The invention claimed is: 
     
       1. A flow guide for directing a fluid flow across a surface of an endoscope, the flow guide comprising:
 a locating arrangement for locating the endoscope with respect to the flow guide such that the surface of the endoscope is disposed generally in a first plane defined along first and second mutually perpendicular directions;   a channel for directing the fluid flow, the channel having sides spaced with respect to each other in the first direction and extending in a third direction perpendicular to the first and second directions;   an outer channel surface extending between the sides of the channel; and   wherein an edge of the outer channel surface is convex-shaped to define an outlet of non-uniform height relative to the first plane, thereby imparting a non-uniform velocity profile to fluid constrained to flow between the edge of the outer channel surface and the first plane.   
     
     
       2. The flow guide of  claim 1 , wherein the edge of the outer channel surface is symmetrical about a third plane perpendicular to the first plane and a second plane defined by the first and third directions. 
     
     
       3. The flow guide of  claim 1 , wherein the edge of the outer channel surface is curved. 
     
     
       4. The flow guide of  claim 1 , wherein the outlet 10 is approximately 5.5 mm wide in the first direction. 
     
     
       5. The flow guide of  claim 1 , wherein the outlet is approximately 0.3 mm high in the third direction at the center of the outlet and approximately 0.7 mm high in the third direction at the sides of the outlet. 
     
     
       6. The flow guide of  claim 1 , wherein the edge of the outer channel surface forms an arc with a radius of approximately 9.5 mm. 
     
     
       7. The flow guide of  claim 1 , wherein the locating arrangement includes a base of a limb disposed generally in the first plane and arranged to rest against the surface of the endoscope. 
     
     
       8. The flow guide of  claim 1 , wherein the flow guide includes a respective limb extending from each of the sides generally in the second direction, each limb defining a limb guide surface extending generally in the third direction and being convex in a plane parallel to the first plane to cause fluid flow from the channel to diverge in the first direction as it flows across the surface of the endoscope. 
     
     
       9. The flow guide of  claim 8 , wherein the locating arrangement includes a base of the respective limb disposed generally in the first plane and arranged to rest against the surface of the endoscope so that the limb guide surfaces extend in the third direction from the surface of the endoscope. 
     
     
       10. The flow guide of  claim 8 , wherein each of the limb guide surfaces is generally curved in a plane defined by the first and second directions. 
     
     
       11. The flow guide of  claim 1 , wherein the edge of the outer channel surface is convex in a plane defined by the first and second directions. 
     
     
       12. The flow guide of  claim 1 , wherein the flow guide is arranged to direct the fluid flow at an angle of approximately 20° to the first plane. 
     
     
       13. The flow guide of  claim 1 , wherein the channel has an inner channel surface extending in the first direction between the sides of the channel, the inner channel surface generally facing the outer channel surface. 
     
     
       14. The flow guide of  claim 13 , wherein the inner channel surface is shaped to form a substantially continuous surface with the surface of the endoscope when the endoscope is secured to the flow guide. 
     
     
       15. The flow guide of  claim 1 , wherein the endoscope is substantially cylindrical and the surface of the endoscope is an end surface of the endoscope, wherein the flow guide is arranged to define a portion of the channel longitudinally along the endoscope for guiding the fluid flow longitudinally along the endoscope. 
     
     
       16. The flow guide of  claim 15 , wherein the channel comprises a chamber between the portion of the channel along the endoscope and a portion of the channel adjacent the edge of the outer channel surface, the chamber being shaped to turn the fluid flow from flowing along the endoscope to flowing across the end surface of the endoscope. 
     
     
       17. The flow guide of  claim 16 , wherein the chamber is shaped to turn the fluid flow through an angle of approximately 110°. 
     
     
       18. The flow guide of  claim 16 , wherein the chamber has a larger cross-sectional flow area than the portion of the channel adjacent the edge of the outer channel surface. 
     
     
       19. The flow guide of  claim 16 , wherein the cross-sectional flow area of the channel decreases from an inlet of the flow guide that is in fluidic communication with the channel to an entrance of the chamber. 
     
     
       20. The flow guide of  claim 19 , wherein the cross-sectional flow area of the chamber increases after the entrance. 
     
     
       21. The flow guide of  claim 1 , wherein the flow guide comprises an inlet in fluidic communication with the channel, the inlet having a larger cross-sectional flow area than the portion of the channel adjacent the edge of the outer channel surface. 
     
     
       22. The flow guide of  claim 1 , wherein the channel is continuous and has no internal obstructions to the fluid flow. 
     
     
       23. The flow guide of  claim 1 , wherein the flow guide is integrally formed with the endoscope or detachable from the endoscope. 
     
     
       24. The flow guide of  claim 23 , wherein the endoscope is substantially cylindrical and the surface of the endoscope is an end surface of the endoscope. 
     
     
       25. The flow guide of  claim 23 , wherein the surface of the endoscope includes a lens or optical window of the endoscope. 
     
     
       26. The flow guide of  claim 23 , in which the endoscope is a laparoscope. 
     
     
       27. A flow guide for directing a fluid flow across a surface of a device, the flow guide comprising:
 a locating arrangement for locating the device with respect to the flow guide such that the surface of the device is disposed generally in a first plane defined along first and second mutually perpendicular directions;   a channel for guiding the fluid flow, the channel having sides spaced with respect to each other in the first direction; and   a respective limb extending from each of the sides generally in the second direction, each limb defining a limb guide surface extending generally in a third direction perpendicular to the first and second directions and being convex in a plane parallel to the first plane to cause fluid flow from the channel to diverge in the first direction as it flows across the surface of the device.   
     
     
       28. The flow guide of claim 27, wherein each of the limb guide surfaces is generally curved in a plane defined by the first and second directions. 
     
     
       29. The flow guide of claim 27, wherein the channel has an outer channel surface extending in the first direction between the sides of the channel. 
     
     
       30. The flow guide of claim 29, wherein an edge of the outer channel surface is convex-shaped to define an outlet of non-uniform height relative to the first plane, thereby imparting a non-uniform velocity profile to fluid constrained to flow between the edge of the outer channel surface and the first plane. 
     
     
       31. The flow guide of claim 29, wherein an edge of the outer channel surface is convex in a plane defined by the first and second directions. 
     
     
       32. The flow guide of claim 29, wherein the flow guide is arranged to direct the fluid flow at an angle of approximately 20° to the first plane. 
     
     
       33. The flow guide of claim 29, wherein the channel has an inner channel surface extending in the first direction between the sides of the channel, the inner channel surface generally facing the outer channel surface. 
     
     
       34. The flow guide of claim 33, wherein the inner channel surface is shaped to form a substantially continuous surface with the surface of the device when the device is secured to the flow guide. 
     
     
       35. The flow guide of claim 29, wherein an inner channel surface facing the outer channel surface is defined by the device when the device is located such that the surface is disposed in the first plane. 
     
     
       36. The flow guide of claim 27, wherein the locating arrangement includes a respective base of each limb disposed generally in the first plane and arranged to rest against the surface of the device so that the limb guide surfaces extend in the third direction from the surface of the device. 
     
     
       37. The flow guide of claim 27, wherein the device is substantially cylindrical and the surface is an end surface of the device, wherein the flow guide is arranged to define a portion of the channel longitudinally along the device for guiding the fluid flow longitudinally along the device. 
     
     
       38. The flow guide of claim 37, wherein the channel comprises a chamber between the portion of the channel along the device and a portion of the channel adjacent the limbs, the chamber being shaped to turn the fluid flow from flowing along the device to flowing across the end surface of the device. 
     
     
       39. The flow guide of claim 38, wherein the chamber is shaped to turn the fluid flow through an angle of approximately 110°. 
     
     
       40. The flow guide of claim 38, wherein the chamber has a larger cross-sectional flow area than the portion of the channel adjacent the limbs. 
     
     
       41. The flow guide of claim 27, wherein the flow guide comprises an inlet in fluidic communication with the channel, which inlet has a larger cross-sectional flow area than the portion of the channel adjacent the limbs. 
     
     
       42. The flow guide of claim 41, wherein the cross-sectional flow area of the inlet is larger than the portion of the channel adjacent the limbs by a factor of at least 6. 
     
     
       43. The flow guide of claim 41, wherein the cross-sectional flow area of the channel decreases from the inlet to an entrance of the chamber. 
     
     
       44. The flow guide of claim 43, wherein the cross-sectional flow area of the chamber increases after the entrance. 
     
     
       45. The flow guide of claim 27, wherein the channel is continuous and has no internal obstructions to the fluid flow. 
     
     
       46. The flow guide of claim 27, wherein a longitudinal portion of the flow guide comprises an inner surface and an outer surface, the inner surface and outer surface being connected to form two tips so that the device is only partially enclosed by the longitudinal portion. 
     
     
       47. The flow guide of claim 46, wherein a distal tip surface is defined between the inner surface and the outer surface adjacent each tip, the distal tip surfaces being in a plane parallel to the first plane but not coplanar with the first plane, such that the surface of the device protrudes longitudinally beyond the distal tip surfaces when the surface of the device is disposed in the first plane. 
     
     
       48. An optical device comprising a transverse end surface including a lens or optical window and a flow guide as claimed in claim 27 for guiding a fluid flow longitudinally along the device and directing the fluid flow across the transverse end surface of the device, wherein the flow guide is integrally formed with the device or detachable from the device. 
     
     
       49. The device of claim 48, wherein the device is substantially cylindrical and the surface is an end surface of the device. 
     
     
       50. The device of claim 48, wherein the device is a medical device. 
     
     
       51. The device of claim 48, in which the device is an endoscope. 
     
     
       52. The device of claim 48, in which the device is a laparoscope. 
     
     
       53. The flow guide of claim 29, wherein an edge of the outer channel surface extends in a second plane defined by the first and third directions to define an outlet. 
     
     
       54. The flow guide of claim 53, wherein the edge of the outer channel surface is convex in the second plane such that the outlet has a non-uniform height relative to the first plane. 
     
     
       55. The flow guide of claim 53, wherein the edge of the outer channel surface is configured such that the outlet has a non-uniform height relative to the first plane. 
     
     
       56. The flow guide of claim 29, wherein an edge of the outer channel surface is arranged to define an outlet between the edge of the outer channel surface and the first plane. 
     
     
       57. The flow guide of claim 56, wherein the fluid flow from the channel passes through the outlet.