US2821634A - X-ray tube head for hazardous locations - Google Patents

Description

Jan. 28, 1958 ca. B. MYERS ETAL 2,821,634

-X-RAY TUBE HEAD FOR HAZARDOUS LOCATIONS Filed Sept. 1, 19s; v 2 She'ets-Sheet 1 INVEN TOR. 650055 5. My!

R'IMARO vV. Comm/v BY Jan. 28, 1958 G. B. MYERS E L 2,321,634

X-RAY TUBE HEAD FOR HAZARDOUSVLOCATQIONS Filed Sept. 1, 1953 2 Sheets-Sheet 2 Ian, 4/

- INVENTOR. @AORGE B. MYERS file/MR0 vv. 6'08EAN add/Mg fin ATTGRNE'XJ X-RAY TUBE HEAD "FOR HAZARDOUS LOCATIONS George B, Myers, Chesterland, and Richard W. Cobean, Clarendon Hills, hlo,"'assignors to Picker X-Ray Corporation Waite Manufacturing Division, Inc., a corporation of Ohio Application September 1, 1253, Serial No. 377,868 4 Claims. (Cl. 250-87) This invention relates to the improvements in an X-ray tube head or similar housing-for use in hazardous locations and more particularly to one in whichthe X-ray tube or other electrical device submerged in a liquid dielectric is ,deenergi'zedor disabled in case a predetermined amount ofdielectric liquidis lost out at a liquidtight housing.

flIhe inventionisembodie'd in an X-ray tube head and one of the objects of the present invention is to provide an X-ray tube head including a liquid-tight housing with an'X-ray tube and electrical energizing means therefor inside of the housing and surrounded by a dielectric liquid substantially filling the housing around the X-ray tube and the energizing means. A chamber in communication with the liquid-containing portion of this housing,

and therefore filled with the dielectric liquid, is provided 1 with a movable wall and means is provided urging this movable wall against the liquid in the chamber. The electrical energizing means includes a switch normally in enabling position, but movable to a disabling position upon predetermined movement of the movable wall upon the loss of a relatively small amount of dielectric liquid from the housing and chamber. In this manner, operation of theX-ray tube is rendered impossible upon the loss of a small amount of dielectric liquid from the tube head.

A further object of the present invention is, to provide novel means for carrying out the above describedpurpose, a preferred form including a liquid-tight expansible bellows as will later appear.

Other objects and advantages of the present invention will be apparent from the accompanying drawings and description and the essential features thereof will be set forth in the appended claims.

' In the drawings Fig. l is a side elevational View of an X-ray tube head embodying this invention,

Fig. 2 is a transverse sectional view enlarged taken along the line 2-2 of Fig. l,

'Fig.- 3 is a fragmental sectional view taken along the line 3-3 of Fig. 2, while 1 Fig. 4 is a diagrammatic showing of the electrical circuits necessary for the operation of this invention.

The invention is shown as applied to a tube head including a housing of liquid-tight character in which is housed an X-ray tube 1 1, a high-tension transformer impeller for moving housing.

Electrical conductors are shown at 14 for energizing;

the head. A pair of arms mounted on trunnions at opposite sides ofsthe head permit a tiltingof'the head.

2,821,634 Patented Jan. 28, 1958 chamber 17 in fixed position at one side of the housing 10.. Communication is provided for the dielectric liquid to pass from housing 10 into the chamber 17 through openlugs 13. It will be understood by anyone skilled in this art that the dielectric liquid surrounds all of the electrical parts housed within the main housing 10, so as to completely insulate the housing from all of the electrical parts and provide a shock proof head. It is possible for Y ('0 12, a filament transformer 13, and, if desired, a pump or j the dielectric liquid around the this dielectric liquid to leak out of the housing 10, which 7 would result in sufiicient loss of dielectric liquid that a short circuit might occur either causing an explosion in the operating room or causing harm to the operator. A very dangerous situation might arise if oil leaked out of the housing 10 and explosive vapors from an operating room entered the housing 10. Then a spark inside the housing due to a discharge to ground, or to a short circuit, might explode the housing. It is the purpose of the present invention to obviate this difiiculty.

Referring to Fig. 2, the liquid holding portion of the chamber 17 is provided with a liquid-tight partition 19 near one end thereof upon which is mounted a switch 20. This structure includes a sleeve 21 which is welded to the cylindrical auxiliary housing or chamber 17 at 22 in a liquid-tight manner. A solid disc-like member 23 is threaded down within the threads 21a of the sleeve and holds a sealing gasket 24 tightly against the shoulder 21b of the sleeve. A lock ring 25 holds the member 23 firmly locked in position. A cap 26 closes the lower end of chamber 17 as viewed in Fig. 2 and this is held in place by meansof a screw 27 which enters a threaded boss 23a which is part of the member 23. Switch 20 is supported on the member 23 by means of binding posts 28 and 29. The binding posts are Welded to the base of the switch 20. The switch 20 has an operating member 20a which bears against a springlike actuator 30.

Another wall confining the dielectric liquid in the chamber 17 comprises a movable diaphragm or bellows 31. In the form shown, an expansible bellows of accordion type is formed in a liquid-tight manner with oil on the outside of the bellows and air on the inside. To this end, the bellows has a sealed connection at the upper end 31a as shown in Fig. 2 so that oil or other dielectric liquid cannot leak out of the space between the auxiliary housing or chamber 17 and the bellows 31. The upper end of the bellows is shown as closed by means of a cap 32, the central opening of which is closed by a button 33, having spring fingers 33a holding it in place. This is not an air-tight connection and permits communication between the interior of the bellows and atmosphere.

Means is provided for urging the movable diaphragm or bellows 31 inwardly against the dielectric liquid in chamber 17. In the form shown this means comprises a long helical spring 34. A plurality of fingers 35 are rigidly secured to the periphery of the circular inner head of the bellows 31 and extend parallel to the axis of the bellows or upwardly as viewed in Fig. 2. Spaced between and parallel to the fingers 35 are a plurality of fingers 36 which are rigidly secured to the cap 32 and extend downwardly as viewed in Fig. 2. These sets of fingers 35 and 36 permit free expansion and contraction of the bellows 31 while at all times guiding the helical spring 34 and holding it in centered operative position.

Various operating circuits for my device will occur to those familar with this art, but a representative energizing diagram has been shown in Fig. 4. Low tension current is supplied from the sourceL-ll, L-2 to an auto transformer 37. Lines 38 and 39 lead to-the'primary of the high-tension transformer 12, with suitable taps being provided so as tovary. thekilovoltage. Another conductor-14tl leads to the filament transformer primary; at 13a, the other side of this winding being connected through line 41 to conductor 38. The central secondary 12b of the high-tension transformer 12 is grounded through resistances 42. These resistances are preferably of nonlinear type and may be of the ceramic resistance known as Thyrite. It is a characteristic of this resistance that it is very high at low voltage but very low resistance at high voltage. Within this central secondary grounded circuit is a milli-ammeter 43 and relay coils 44a grounded at 45 and adapted to energize relay winding 44a which closes normally open switch 44b upon too high an overload in the central secondary circuit. Upon the occurrence of such an overload, the presence of the non-linear resistances 42 prevents dangerous sparking. Closing of switch 44b energizes relay winding 47a and lights warning light L. Energization of winding 47a moves its armature 47b from its normal full-line position to its broken line position thus opening the control circuit for energizing transformer 12. For initiating an exposure of the X-ray tube, a line 46 is tapped into the auto transformer and leads through a normally closed switch 47b, line 48, normally closed switch 49b, and line 50, to one contact of the normally open exposure switch 51. The other contact of this switch is connected through line 52, switch 53 in fiuoroscopy position F, line 54, relay winding 55a and lines 56 and 57 back to the auto transformer. Another relay winding 53a is connected between line 52 and line 56. This relay is provided with an armature 58b which connects line 39 to line 59 bypassing the normally open armature 55b of relay 55 as presently will appear.

An exposure for fluoroscopy is initiated by pressing the actuator 53 to close the switch there, thus completing the circuit previously mentioned which energizes transformer 12 and tube 11, through starting resistance R1. Switch 60 is then on its F contact. Upon energization of relay coil 55a, the armature 55b is caused to close against contact 61 so as to start the energization of the X-ray tube. Energization of winding 55a also closes the armature 550 so as to energize relay coil 58a which in turn attracts the armature 58b to close this switch against contact 62, thus by-passing the starting resistance R1.

For radiography the switches 53, 60 and 64 are placed in contact with the R buttons or contacts. The timer 65 is then set for the desired time and the timer switch T is moved to its broken line position. This completes a circuit from the auto transformer 37 through line 46, switch 47b, line 48, switch 4%, line 50, switch T, line 66, relay coil63a, and lines 56 and 57 back to the transformer. Energization of relay 63a moves its armature or switch 63b from its normal full line position to the broken line position. Closing of the timer switch T initiates an exposure through relays 55a and 58a as previously described.

Upon the loss of suflicient dielectric liquid from the main housing 10 and the auxiliary housing 17, to permit the bellows 31 to be pushed by spring 34 against the actuator 30, the switch 20 is closed to the broken line position of Fig. 4, thus completing a circuit through the secondary 62b of transformer 62, the primary of which 62a is energized from the auto transformer. This energizes the relay coil 49a which causes the normally closed switch or armature 49b to open against contact 67, thus opening the circuit controlling energizing the primary 12a of the high-tension transformer'12 and stopping an exposure if one is in progress or preventing one otherwise. Light L is also energized. This light will remain energized until additional dielectric liquid has been placed in the housings 10 and 17 so as to cause the bellows 31 to move away from the actuator 30 thus allowing switch 20 to resume its normally open position.

What we claim is:

1. In combination, an X-ray tube head including a liquid-tight housing, an X-ray tube within said housing, an electrical energizing circuit for said tube including a switch normally enabling said circuit and movable to a circuit disabling position, a dielectric liquid substantially filling said housing around said tube, means providing a chamber in communication with said liquidcontaining portion of said housing whereby said chamber is filled with liquid, said last named means including a movable wall of said chamber, means urging said movable wall against said liquid in said chamber, and means responsive to predetermined movement of said wall into said chamber by said urging means for causing movement of said switch to said disabling position.

2. In combination, an X-ray tube head including a liquid-tight housing, an X-ray tube and electrical energizing means therefor within said housing, said energizing means including a switch normally enabling said means and movable to a means disabling position,-a dielectric liquid substantially filling said housing around said tube and said means, there being a liquid-tight auxiliary chamber mounted on said housing in communication with said liquid containing portion of said housing whereby said auxiliary chamber is filled with liquid, a movable diaphragm forming a portion of a wall of said auxiliary chamber, a spring urging said diaphragm into said chamber, a second switch having an actuator nor-. mally spaced from said diaphragm and in the path of movement of said diaphragm for movement to a means disabling position under urging of said spring upon loss of a predetermined amount of liquid from said housing and said auxiliary chamber, and an operative connection between said second switch in means disabling position and said first-named switch for moving the latter to means disabling position. I

3. In combination, an X-ray tube head including a liquid-tight housing, an X-ray tube and electrical energi'zing means therefor within said housing, said energizing means including a switch normally enabling said means and movable to a means disabling position, a dielectric liquid substantially filling said housing around said tube and said means, there being a liquid-tight auxiliary chamber mounted on said housing in communication with said liquid containing portion of said housing whereby said auxiliary chamber is filled with liquid, an expansible liquid-tight bellows in said auxiliary chamber having an exterior face in contact with said liquid and having an interior face in communication with atmosphere, spring means urging said bellows against said liquid, a second switch having an actuator normally spaced from said bellows and in the path of movement of said bellows for movement of 'said'seccnd switch to a means disabling position by expansion of said bellows u nd'erurging of said spring means upon loss of a predetermined amount of liquid from said housing and said auxiliary chamber, and an operative connection between said second switch in means disabling position and said first-named switch for moving the latter to means disabling position.

4. In combination, a liquid-tight housing, an electrical device within said housing, energizing means for said electrical device including a switch normally enabling said means and movable to a means-disabling position, a dielectric liquid substantially filling said housing around said device, means providing a chamber in communication with said liquid-containing portion of said housing whereby said chamber is filled with liquid, said last named means including a movable wall ofsaid chamber, means urging said movable wall against said liquid in said chamber, and means responsive to predetermined movement of said wall into said chamber by said urging means for causing movement of said switch to said disabling position.

References Cited in the file of this patent UNITED STATES PATENTS 1,543,654 Coolidge June 23, 1925 1,866,141 Wantz July 5, 1932 1,869,176 St. Palley July 26,1932 1,877,260 Wantz Sept. 13, 1932 2,259,037 Graves Oct. 14, 1941

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