X-ray tube casing with integral heat exchanger

Abstract

An x-ray tube casing is provided which includes a housing having a heat exchanger integrally formed thereon in an additive manufacturing process. The additive manufacturing process allows for tight tolerances with regard to the structure for the casing and the internal passages of the heat exchanger to significantly reduce the size and weight of the casing. The casing additionally includes a fluid distribution manifold that effectively distributes the cooling fluid within the casing to more efficiently provide cooling to the x-ray tube insert disposed within the casing.

Claims

1. An x-ray tube casing for an x-ray tube insert, the casing comprising: a housing adapted to receive at least a portion of the x-ray tube insert therein; a heat exchanger including a number of fluid flow passages, the heat exchanger formed on an exterior surface of the housing; and a fluid expansion bellows disposed within the housing.

2. The x-ray tube casing of claim 1 wherein the number of fluid flow passages include first fluid flow passages and second fluid flow passages.

3. The x-ray tube casing of claim 2 wherein first fluid flow passages and the second fluid flow passages are countercurrent to one another.

4. The x-ray tube casing of claim 2 wherein the first fluid flow passages and the second fluid flow passages have different dimensions.

5. The x-ray tube casing of claim 2 wherein one of the first or second fluid flow passages is in fluid communication with an interior space of the housing.

6. The x-ray tube casing of claim 1 further comprising a fluid distribution manifold disposed within an interior of the housing.

7. The x-ray tube casing of claim 6 wherein the manifold is integrally formed with the housing.

8. The x-ray tube casing of claim 1 wherein the housing includes an oil pump chamber formed on the exterior of the housing.

9. The x-ray tube casing of claim 8 wherein the oil pump housing is fluid communication with the number of fluid passages in the heat exchanger.

10. The x-ray tube of claim 1 wherein the bellows includes a peripheral sealing bead engaged with the housing.

11. The x-ray tube casing of claim 1 wherein the housing is formed in a direct metal laser melting additive manufacturing process.

12. The x-ray tube casing of claim 1, wherein the housing comprises: a mid casing within which at least a part of the x-ray tube insert is disposed; and an end casing secured to the mid casing within which at least a portion of the x-ray tube insert is disposed, the end casing including the heat exchanger having a number of fluid flow passages formed on an exterior surface of the end casing.

13. An x-ray tube comprising: an x-ray tube insert; and an x-ray tube casing including a housing formed in an additive manufacturing process and within which the x-ray tube insert is placed, the housing including a side wall and a heat exchanger formed on an exterior of the side wall; wherein the heat exchanger comprises: a first internal passage having an inlet and an outlet, wherein the first internal passage is not in fluid communication with an interior space defined by the housing; and a second internal passage having an inlet and an outlet, wherein the second internal passage is in fluid communication with the interior space defined by the housing.

14. The x-ray tube of claim 13 wherein the housing includes a fluid distribution manifold disposed within an interior space defined by the housing.

15. The x-ray tube of claim 13 wherein the housing includes a fluid expansion bellows disposed over one end of the housing.

16. The x-ray tube of claim 13 wherein the housing comprises: a mid casing within which at least a part of the x-ray tube insert is disposed; and an end casing secured to the mid casing within which at least a portion of the x-ray tube insert is disposed, the end casing including the heat exchanger having a number of fluid flow passages formed on an exterior of a side wall of the end casing.

17. A method for exchanging heat from a cooling fluid disposed within an x-ray tube, the method comprising the steps of: additively manufacturing an x-ray tube casing including a housing having a heat exchanger formed on an exterior surface of a side wall of the housing, the heat exchanger including at least one passage in communication with an interior space defined by the housing; placing an x-ray tube insert within the interior space defined by the central frame; placing an amount of cooling fluid in the interior space between the x-ray tube insert and the housing; and directing a flow of the cooling fluid through the at least one passage to exchange heat from the cooling fluid wherein the housing includes a fluid distribution manifold disposed within the interior of the housing.

18. The method of claim 17 further comprising the step of directing the cooling fluid to various areas of the interior of the housing through the manifold after directing the flow of cooling fluid through the at least one passage.

19. An x-ray tube casing for an x-ray tube insert, the casing comprising: a housing adapted to receive at least a portion of the x-ray tube insert therein; a heat exchanger including a number of fluid flow passages, the heat exchanger formed on an exterior surface of the housing; wherein the number of fluid flow passages include first fluid flow passages and second fluid flow passages; and wherein first fluid flow passages and the second fluid flow passages are countercurrent to one another.

20. An x-ray tube casing for an x-ray tube insert, the casing comprising: a housing adapted to receive at least a portion of the x-ray tube insert therein; a heat exchanger including a number of fluid flow passages, the heat exchanger formed on an exterior surface of the housing; and wherein the housing comprises: a mid casing within which at least a part of the x-ray tube insert is disposed; and an end casing secured to the mid casing within which at least a portion of the x-ray tube insert is disposed, the end casing including the heat exchanger having a number of fluid flow passages formed on an exterior surface of the end casing.

21. An x-ray tube comprising: an x-ray tube insert; and an x-ray tube casing including a housing formed in an additive manufacturing process and within which the x-ray tube insert is placed, the housing including a side wall and a heat exchanger formed on an exterior of the side wall; wherein the housing includes a fluid expansion bellows disposed over one end of the housing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an isometric view of a prior art x-ray tube casing.

(2) FIG. 2 is a schematic view of the prior art x-ray casing of FIG. 1.

(3) FIG. 3 is an isometric view of an x-ray tube casing in accordance with an exemplary embodiment of the invention.

(4) FIG. 4 is an isometric view of the x-ray end casing in accordance with an exemplary embodiment of the invention.

(5) FIG. 5 a schematic view of the x-ray tube and x-ray casing of FIG. 3.

(6) FIG. 6 is a partially broken away, isometric view of the x-ray tube end casing of FIG. 4.

(7) FIG. 7 is a partially broken away, isometric view of the x-ray tube end casing of FIG. 4.

(8) FIG. 8 is a partially broken away cross-sectional view of the x-ray tube end casing of FIG. 4.

(9) FIG. 9 is a cross-sectional view along line 9-9 of FIG. 4.

(10) FIG. 10 is a partially broken away cross-sectional view of the x-ray casing of FIG. 9.

(11) FIG. 11 is an isometric view of an x-ray tube casing in accordance with another exemplary embodiment of the invention.

(12) FIG. 12 is a top plan view of the x-ray tube casing of FIG. 11.

DETAILED DESCRIPTION OF THE DISCLOSURE

(13) In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments, which may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments, and it is to be understood that other embodiments may be utilized and that logical, mechanical, electrical and other changes may be made without departing from the scope of the embodiments. The following detailed description is, therefore, not to be taken in a limiting sense.

(14) Looking now at FIGS. 3 and 4, in the illustrated exemplary embodiment the x-ray tube insert (not shown) is disposed within an x-ray tube casing 100 to form the x-ray tube 11. The casing 100 includes a hollow housing or body 102, a high voltage (HV) connector/end cap 104 secured to the housing 102 adjacent the cathode assembly (not shown) and a cover plate 106 (FIG. 10) secured to the housing 102 opposite the HV connector 104. The hollow housing 102 is formed of a generally cylindrical mid casing 108 that is open at each end 107, 109 and within which the cathode assembly and anode (not shown) of the x-ray tube 11 are disposed. The housing 102 additionally includes a generally cylindrical end casing 110 mounted to and/or disposed around one open end 109 of the mid casing 108 which itself includes an open end 111 opposite the mid casing 108 and which encloses the shaft 61 and bearing assembly 63 (FIG. 9) of the x-ray source (not shown) that extend outwardly from the mid casing 108.

(15) Referring now to the exemplary embodiments illustrated in FIGS. 3-4, the end casing 110 additionally encloses a stator basket (not shown) disposed within the interior of the end casing 110 around the shaft 61 and bearing assembly 63. The stator basket is operably connected to a voltage source (not shown) via a suitable connector (not shown) extending through an aperture 116 in the end casing 110 in order to supply current to the stator basket to enable the basket to interact with and spin the shaft 61 when the x-ray tube insert is operated.

(16) Looking now at the exemplary embodiment illustrated in FIGS. 9-10, the open end 111 of the end casing 110 is enclosed by the cover plate 106 that engages a flexible bladder or fluid expansion bellows 117 between the cover plate 106 and the open end 111 of the end casing 110. The bellows 117 is formed of a suitable material, such as a rubber bladder, and extends over the entire open end 111 of the end casing 110. In the exemplary illustrated embodiment, the bellows 117 is generally circular in shape and includes a curved cross-section to provide the bellows 117 with the capacity to expand and contract upon differential pressures exerted on the bellows 117. To maintain a fluid-tight seal in conjunction with the cover plate 106 and the end casing 110, the bellows 117 includes a peripheral cylindrical bead 118 formed around the entire periphery of the bellows 117. The bead 118 is disposed within and compressed by aligned complementary recesses 120, 122 formed in the cover plate 106 and end casing 110, respectively, to provide a fluid tight seal, while also allowing the bellows 117 to expand and contract between the cover plate 106 and the end casing 110. To accommodate for the expansion and contraction, the cover plate 106 includes a vent 124 that allows air to enter and exit the space 126 defined between the bellows 117 and the cover plate 106.

(17) Opposite the cover plate 106, the end casing 110 is secured to the mid casing 108 in a suitable manner to seal the end casing 110 to the mid casing 108. With the end casing 110 thus sealed, it is possible to fill the end casing 110 with an amount of dielectric oil 136, such as via sealable oil fill port 139, in order to provide cooling to the operation of the shaft 61 and beating assembly 63.

(18) As illustrated in the exemplary embodiment of FIG. 5, when assembled with the connector/end cap 104 and cover plate 106, the housing 102 defines an interior space (not shown) within which the portion of the x-ray tube insert including the cathode assembly and anode/target 56 is located. The mid casing 108 and end casing 110 of the housing 102 effectively form a fluid-tight enclosure around the interior space 134 in order to retain an amount of a cooling fluid/dielectric oil 136 in the interior space 134 between the x-ray tube insert/source 14 and the housing 102. The oil 136 is introduced through a sealable fill port 139 formed in the end casing 110 and functions to cool the internal components of the x-ray tube insert 14 by flowing around and thermally contacting the frame 50 of the x-ray tube/source 14 and drawing the heat generated by the operation of the x-ray tube insert 14 out of the x-ray tube insert 14 via contact with the frame 50.

(19) Referring now to FIGS. 4-8, in order to remove the heat from the insert cooling fluid/dielectric; oil 136, the casing 100, or a component part or parts of the casing 100, e.g. the entire housing 102, the mid casing 108, the end casing 110, the end cap 104, or any combination thereof can be formed to include a passage(s) 138 or channels 152,154 therein to enable a cooling fluid 140 to pass through a side wall 121 of the casing 100 or component part thereof. This provides the casing 100 with an integral cooling functionality to enable the casing 100 to effectively remove the heat generated by the operation of the shaft 61 and bearing assembly 63.

(20) In one exemplary embodiment schematically illustrated in FIG. 5, the passage(s) 138 can be formed as a continuous passage 138 throughout the side wall 121 of the housing 102 or portion thereof, or can be formed as individual passages 138 each extending through the side wall 121. The passage(s) 138 are each connected to a source of a cooling fluid 140, such as water, a water/glycol mixture or any other suitable fluid having desirable heat exchange properties, that is directed into the passages 138 to flow from an water inlet header 142, 157 of each passage 138 to a water outlet header 144, 159. The heat transfer properties of water are significantly superior to dielectric oil, so the total heat transfer is determined by the heat transfer from the vacuum vessel wall/frame 50 to the oil 136. Each passage 138 is formed within the side wall 121 to retain a thickness of the side wall 121 between the interior space 134 of the housing 102 and the passages 138 that is sufficient to enable the cooling fluid 140 flowing through the passages 138 to thermally contact the oil 136 located within the interior space 134, but without enabling the oil 136 and fluid 140 to come into direct contact with one another. This provides effective heat exchange due to the large surface area of the side wall 121 that is in direct contact with the dielectric oil 136 flowing in the space or gap 180 between the x-ray tube insert 14 and the side wall 121. The cooling fluid 140 can be introduced into the inlet end 142 of the passages 138 by a pump 146 connected to a chilled reservoir 148 of the cooling fluid 140 that operates to cool the heated cooling fluid 140 exiting the passages 138 in the housing 102. The operation of the pump 146 can be controlled to direct the cooling fluid 140 into the passages 138 at a rate commensurate with the operation of the x-ray tube 14 in order to provide the proper cooling to the dielectric oil 136.

(21) The dielectric oil 136 can be allowed to come into thermal contact with the cooling fluid 140 in passage(s) 138 solely by convection, where the heat absorbed by the oil 136 adjacent the frame 50 causes the heated oil 136 to move outwardly from the frame 50 where it is heated through the interior space 134 towards the housing 102. Upon reaching the housing 102, the heated oil 136 thermally contacts the cooling fluid 140 flowing through the passage(s) 138 in order to cool the oil 136, which subsequently flows back towards the flame 50 to displace heated oil 136 near the frame 50. This embodiment is applicable for lower average power x-ray tubes 14 employed on surgical C-arms and further reduces cost, size and weight due to elimination of the oil pump 150.

(22) Alternatively, the oil 136 can be circulated into thermal contact with the cooling fluid 140 by a pump 150 that withdraws heated oil 136 from the interior space 134 via suitable conduit connected to an outlet header 153 and through an oil filter 149 prior to re-introduction of the oil 136 from the filet 149 via a suitable conduit into the interior space 134 of the housing 102 through an inlet header 155. In this manner the oil 136 is drawn into thermal contact with the cooling fluid 140 flowing through the passage(s) 138 in order to cool the oil 136.

(23) With particular regard to the illustrated exemplary embodiment in FIGS. 4 and 6-8, the casing 100, or a component part of the casing 100, such as the entire housing 102, the mid casing, the end casing 110, or any combination thereof can be formed to have internal countercurrent channels 152,154 separated by plates 151 and extending through the side wall 121 of the end casing 110/component part of the casing 100 as an alternative to the passages 138. As illustrated with respect to the end casing 110, the channels 152,154 and plates 151 are located within an integral heat exchanger 160 formed directly on and integrally with the exterior of the side wall 121 of the end casing 110.

(24) Within the heat exchanger 160, as shown in the illustrated exemplary embodiment of FIGS. 6 and 7, the channels 152 are connected between an oil inlet header 153 and an oil outlet header 155 to provide a first flow path 156 for the heated dielectric oil 136. Oil 136 is drawn from the outlet header 155 via suitable conduit connected to a pump 150, which can be disposed directly in a pump chamber or housing 170 on the end casing 110 (FIGS. 11-12), that is operable to withdraw heated oil 136 from the interior 134 of the end casing 110. Additionally, the end casing 110/heat exchanger 160 can he formed to additionally integrally connect the oil outlet header 155 with the manifold 164 for directing the cooled oil 136 back into the interior 134 of the casing 100. In the exemplary embodiment illustrated in FIGS. 11 and 12, the housing 170 is formed integrally with the remainder of the end casing 110, such as in the additive manufacturing process, and includes an oil inlet and an oil outlet formed therein. In this manner, the oil inlet port 153 and oil outlet port 155 are eliminated from the end casing 110, thereby further reducing the number of hoses and other connections required for operation of the tube 11.

(25) Further, as shown in the illustrated exemplary embodiment of FIGS. 12-13, the channels 154 are connected between a water inlet header 157 and a water outlet header 159 to provide a second, countercurrent flow path 158 for the cooling fluid/water 140 that is directed into and out of the channels 154 from a reservoir 148 by suitable conduits connected to a pump 146. While any configuration for the channels 152,154 is contemplated as being within the scope of the invention, as shown in the exemplary embodiment of FIG. 8, either or both of the channels 152,154 can be manufactured as a number of conduits 161 separated by fins 162 in order to increase the thermal contact and consequent heat transfer between the oil 136 and cooling fluid 140 flowing through the channels 152,154. These channels 152,154 can also be manufactured to have an angular slope in order to provide additional structural integrity to the channels 152,154. Additionally, the number of conduits 161 formed in the respective channels 152 and 154 can be formed to be the same or different from one another in order to achieve the desired heat exchange within the heat exchanger 160 including the channels 152,154.

(26) Referring now to the exemplary illustrated embodiment of FIGS. 9 and 10, from the oil outlet header 155 the cooled dielectric oil 136 is directed into a fluid distribution manifold 164 disposed within the end casing 110 adjacent the bellows 117, and in the illustrated exemplary embodiment integrally formed with the end casing 110. The manifold 164 extends across the interior of the end casing 110 and includes a number of spaced nozzles or orifices 166,168 extending therethrough. The orifices 166 are located around the periphery of the manifold 164 and serve to direct an amount of the cooled dielectric oil 136 into the interior 134 of the end casing 110, where the oil 136 can thermally contact the frame 50 of the x-ray tube insert 14. The orifice 168 is disposed generally centrally on the manifold 164 in alignment with the bearing assembly 63 in order to direct an amount of the cooled dielectric oil 136 into the shaft 61 and bearing assembly 63.

(27) As the passages 138 or channels 152,154 are formed directly within the side wall 121 of the casing 100, manufacturing processes with tight tolerance controls are necessary to form the casing 100. In order to reduce costs, weight and to provide the intricately formed side wall 121 with the internal passages 138 or channels 152,154 as described, the casing 100/housing 102/mid casing 108/end casing 110 may be manufactured or formed, at least in part or entirely, via one or more additive manufacturing techniques or processes, thus providing for greater accuracy and/or more intricate details within the casing 100/housing 102/mid casing 108/end casing 110 than previously producible by conventional manufacturing processes. As used herein, the terms additively manufactured or additive manufacturing techniques or processes include but are not limited to various known 3D printing manufacturing methods such as Extrusion Deposition, Wire, Granular Materials Binding, Powder Bed and Inkjet Head 3D Printing, Lamination and Photo-polymerization.

(28) In one embodiment, the additive manufacturing process of Direct Metal Laser Melting (DMLM) is an exemplary method of manufacturing the casing 100/housing 102/mid casing 108/end casing 110 or components thereof described herein. DMLM is a known manufacturing process that fabricates metal components using three-dimensional information, for example a three-dimensional computer model of the casing 100/housing 102/mid casing 108/end casing 110. The three-dimensional information is converted into a plurality of slices where each slice defines a cross section of the component for a predetermined height of the slice. The casing 100/housing 102/mid casing 108/end casing 110, such as the side wall 121 of the end casing 110, is then built-up slice by slice, or layer by layer, until finished. Each layer of the casing 100/housing 102/mid casing 108/end easing 110 is formed by melting or fusing layers of metallic powders, such as aluminum powders, or other materials/metals, such as stainless steel, to one another using a laser.

(29) Although the methods of manufacturing the casing 100/housing 102/mid casing 108/end casing 110 including the internal passages 138 or channels 152,154 have been described herein using DMLM as an exemplary method, those skilled in the art of manufacturing will recognize that any other suitable rapid manufacturing methods using layer-by-layer construction or additive fabrication can also be used, These alternative rapid manufacturing methods include, but not limited to, Direct Metal Laser Sintering (DMLS), Selective Laser Sintering (SLS), 3D printing, such as by inkjets and laserjets, Sterolithography (SLS), Direct Selective Laser Sintering (DSLS), Electron Beam Sintering (EBS), Electron Beam Melting (EBM), Laser Engineered Net Shaping (LENS), Laser Net Shape Manufacturing (LNSM) electron beam powder bed fusion and Direct Metal Deposition (DMD).

(30) With the precise manufacturing tolerances provided through the use of the additive manufacturing process for the construction of the casing 100, the passages 138 or channels 152,154 can be formed with a width and/or height of between 1.0 mm-2.0 mm, and in other embodiments between 1.4 mm and 1.8 mm, within the heat exchanger 160. Further, the precise control of the overall shape of the casing 100, including the mid casing 108 and end casing 110, relative to the shape of the x-ray tube insert 14 allows for a reduction in size of the oil gap 180 between the frame 50 of the x-ray tube insert 14 and the side wall 121 of the casing 100 to significantly increase the heat transfer coefficient compared to traditional x-ray casings, which is achieved by maintaining a smaller hydraulic diameter of the oil layer/gap 160.

(31) In addition, while the additive manufacturing process employed to construct the casing 100, e.g., the end casing 110, allows for precise manufacturing tolerances, the nature of the material(s) used in these processes results in relatively rough or uneven surfaces for the end casing 110. As a result, these uneven or rough surfaces within the passages 138 or channels 152,154 provide even further enhancement to the heat exchange properties of the heat exchanger 160 including the passages 138 or channels 152,154 due to the increased surface area within the passages 138 or channels 152,154 from the rough surfaces.

(32) With the additive manufacturing process for the casing 100 and/or component parts thereof, such as the entire housing 102, the mid casing 108 and/or in particular the end casing 110, the incorporation of the heat exchanger 160 directly onto the end casing 110 allows for a significant reduction in the size and weight of the x-ray tube 12, including the insert 14 and the casing 100. The end casing 110 structurally incorporates a number of previously external or additional components into the end casing 110 to accomplish this, as well as to eliminate a number of connecting hoses, seals and resulting potential leak points. The end casing 110 also provides directed cooling to the insert 14 and the bearing assembly via the manifold 164 and internally accommodates for expansion of the oil 136 through the use of the bellows 117, all within the structure of the end casing 110.

(33) As a result of this improved structure for the casing 100, and in certain exemplary illustrated embodiments the end casing 110, the smaller and lighter x-ray tube 11 provides improved angulation of the tube 11 around a patient to improve view angles and provide better treatment. In addition, the smaller footprint foe the tube x-ray tube 11 provides better access to a patient and enables lower C-arm static and dynamic loads, with resulting faster spin speeds and lower costs for the gantry.

(34) The written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.