1. A radial clearance measurement system, comprising:
one or more reference features disposed on a rotating component having an otherwise continuous surface geometry, wherein the rotating component is subject to a range of axial displacement along an axis about which the rotating component rotates;
a radial clearance sensor disposed on a housing held relatively stationary relative to the rotating component, wherein the radial clearance sensor is configured to generate a signal indicative of capacitance between the radial clearance sensor and the rotating component, the radial clearance sensor comprising:
a probe tip comprising an electrode, wherein the electrode comprises a length along the axis greater than the range of axial displacement of the rotating component, wherein an aspect ratio of an axial length of at least one of the one or more reference features on the rotating component to an axial length of the probe tip ranges from about 1:2 to about 1:8;
a processing unit configured to process the signal to estimate a clearance between the rotating component and the housing.
2. The radial clearance measurement system of claim 1, wherein the radial clearance sensor is configured to generate the signal while the rotating component moves relative to the housing.
3. The radial clearance measurement system of claim 1, further comprising:
an excitation source configured to supply excitation signals to the radial clearance sensor; and
a phase detector configured to detect a plurality of reflected signals and to perform a plurality of phase measurements to determine a phase between each of the reflected signals and the respective excitation signals.
4. The radial clearance measurement system of claim 1, wherein the one or more reference features comprise a first notch having a first depth and a second notch having a second depth different than the first depth.
5. The radial clearance measurement system of claim 1, further comprising a clearance control unit coupled to the processing unit for controlling the clearance between the rotating component and the housing based upon the clearance estimated by the processing unit.
6. The radial clearance measurement system of claim 1, wherein the electrode comprises a rectangular head, and wherein the width of the rectangular head is less than a corresponding width of the one or more reference features.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1-36. (canceled)
37. A safety needle attachment for surrounding a needle having a longitudinal axis, comprising:
a hub;
a sleeve surrounding the hub and slidable relatively to hub in the axial direction;
wherein the sleeve has a radially elastically deformable portion, and the hub has a radially converging or diverging portion,
and wherein the sleeve is slidable in a first axial direction between a first position for fully or substantially fully surrounding the needle with the sleeve, and a second position for exposing the needle, wherein sliding between the first and second positions causes elastic radial deformation of the expandable portion engaging with the converging or diverging portion, and wherein the sleeve is further slidable in a second, opposite, axial direction between the second position and a third position for fully surrounding the needle by the sleeve, the force for sliding between the second and third positions being provided by the stored elastic energy in the radially deformable portion.
38. An attachment as claimed in claim 37, wherein the portion of the sleeve is elastically deformable radially outwardly, and the hub has a radially diverging portion.
39. An attachment as claimed in claim 37, wherein the third position of the sleeve is further towards the injection end of the needle than the first position.
40. An attachment as claimed in claim 39, wherein a latching arrangement engages when the sleeve reaches the third position to prevent subsequent movement of the sleeve in the first axial direction.
41. An attachment as claimed in claim 40, wherein the latching arrangement comprises a tab of the sleeve which engages with an end face of the hub.
42. An attachment as claimed in claim 39, further comprising a mechanism for initially limiting movement of the sleeve in the second axial direction when the sleeve is in the first position.
43. An attachment as claimed in claim 39, wherein mechanism releases after initial movement in the first axial direction, and thereafter permits the sleeve to move in the second axial direction to the third position.
44. An attachment as claimed in claim 42, wherein the mechanism comprises a radially extending pin of the sleeve which is held in a first position, and a pawl of the hub which is tripped by the pin upon initial movement of the sleeve in the first axial direction.
45. An attachment as claimed in claim 37, wherein an intermediate position is provided between the first and second positions of the sleeve, in which the sleeve is retained in position.
46. An attachment as claimed in claim 45, wherein the injection end of the needle projects partially from the sleeve in the intermediate position.
47. An attachment as claimed in claim 37, wherein the third position of the sleeve is the same axially as the first position.
48. An attachment as claimed in claim 47, wherein movement of the sleeve in the first axial direction causes rotation of the sleeve about the longitudinal axis.
49. An attachment as claimed in claim 48, wherein an intermediate position is provided between the first and second positions of the sleeve, in which the sleeve is retained in position.
50. An attachment as claimed in claim 49, wherein the injection end of the needle projects partially from the sleeve in the intermediate position.
51. An attachment as claimed in claim 49, wherein the sleeve is held in the intermediate position by engagement of the expandable portion of the sleeve over a tab of the hub.
52. An attachment as claimed in claim 51, wherein the rotation of the sleeve about the longitudinal axis is such that the expandable portion does not engage the tab of the hub when the sleeve moves from the second to the third positions.
53. An attachment as claimed in claim 37, wherein the radially converging or diverging portion of the hub comprises at least one recess for engaging with the deformable portion of the sleeve in a starting position of the sleeve, and otherwise has a substantially smooth outer surface.
54. An attachment as claimed in claim 53, wherein the smooth outer surface is conical.
55. An attachment as claimed in claim 53, wherein the smooth outer surface is polygonal in cross section perpendicular to the longitudinal axis.
56. An attachment as claimed in claim 53, wherein the starting position of the sleeve causes the needle to project from the sleeve, and wherein the attachment further comprises a cap.
57. An attachment as claimed in claim 53, wherein the hub further comprises a head, and wherein the deformable portion engages under the head in the third position of the sleeve.
58. An attachment as claimed in claim 37, wherein the radially converging or diverging portion of the hub comprises at least one track running the length of the hub, and a branch to the track which defines a recess for engaging with the deformable portion of the sleeve in a starting position of the sleeve.
59. An attachment as claimed in claim 58, wherein the starting position of the sleeve causes the needle to project from the sleeve, and wherein the attachment further comprises a cap.
60. An attachment as claimed in claim 58, wherein the hub further comprises a head, and wherein the deformable portion leaves the track in the third position of the sleeve and engages under the head.
61. An attachment as claimed in claim 37, wherein the deformable portion of the sleeve comprises a plurality of circumferentially spaced tines.
62. An attachment as claimed in claim 37, wherein the vessel for containing a medicament comprises a syringe.
63. An attachment as claimed in claim 37, further comprising a removable locking ring connected to the hub andor the sleeve for preventing movement of the sleeve relative to the hub.
64. An attachment as claimed in claim 63, wherein the removable locking ring is frangibly connected to the needle hub andor the sleeve.
65. An attachment as claimed in claim 37, wherein the sleeve is, prior to use, not under any substantial load.
66. An attachment as claimed in claim 37, wherein an end of the hub is adapted for connection to a Luer connector.
67. An attachment as claimed in claim 37, wherein the radially converging or diverging portion comprises a frusto-conical surface.
68. An attachment as claimed in claim 37, wherein the elastic properties of the deformable portion of the sleeve are provided by a circumambient spring.
69. A safety needle assembly, comprising:
a needle having a longitudinal axis having one end for connection to an outlet of a vessel for containing a medicament; and
an attachment as claimed in any preceding claim disposed over the needle.
70. An injection device comprising:
a vessel for containing a medicament; and
an assembly as claimed in claim 69.
71. An injection device as claimed in claim 70, wherein the needle hub is integral with the vessel.
72. A syringe comprising an injection device as claimed in claim 70, wherein the vessel comprises a barrel and the syringe further comprises a piston in the barrel.
73. A safety needle assembly according to claim 69, wherein the vessel is prefilled and sealed to prevent evaporation or loss of medicament.