US 3023791 A
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March 6, 1962 R. c. STRAIN 3,023,791
FLUID FILLING APPARATUS Filed Sept. 4, 1957 IN VEN TOR.
'2 H 5 ROBERT C. STRAIN J BY ATTORNEY United States Patent 3,023,791 FLUID FILLING APPARATUS Robert C. Strain, Danville, Ill., assignor to General Electric Company, a corporation of New York Filed Sept. 4, 1957, Ser. No. 681,985 Claims. (Cl. 141270) My invention relates to apparatus for filling containers with fluid, and more particularly to apparatus for filling enclosed electrical devices with hardenable liquid insulating material.
Electrical apparatus such as fluorescent lamp ballasts are often placed in metal containers and embedded in a hardenable liquid insulating material such as hot sandfilled asphalt by manually pouring the hot asphalt into the container over the ballast components until the container is full. The container is then covered and the asphalt allowed to cool and set. This manual potting operation, as it has become called, has many disadvantages heretofore believed inherent and insurmountable. For example, the asphalt must be kept at a fairly high temperature and can burn the hands of an operator. It must be poured very rapidly into the container in order to prevent freezing and resultant voids and yet must be controlled to fill the container completely so as to produce good thermal contact with the cover. There is, therefore, considerable spilling and spattering of the hot asphalt even in the hands of an experienced operator. Attempts to prevent spilling by conventional liquid level controlling apparatus have not been successful since the surface of the hot asphalt is not level at the time flow must be stopped. In general, this potting operation may be characterized as messy.
In addition, there is a high rate of ballast spoilage due to voids, especially with shallow ballasts because of insuflicient flow clearance between the ballast components and the case. Raising the temperature of the asphalt to reduce viscosity and increase flow penetration causes damage to the electrical connections within the ballast and results in flow of the asphalt out through the lead-accommodating apertures in the case. Conventional automatic gravity flow filling apparatus are no more eflective in eliminating these voids than this manually controlled potting operation, while conventional pressure rlling apparatus are not suitable since they result in the extrusion of the hot asphalt through the lead accommodating apertures and through the filling aperture.
Accordingly, an important object of my invention is to provide apparatus for automatically and mechanically performing this potting operation.
Another object of the invention is to provide apparatus for embedding an electrical device in hardenable liquid insulating material within an enclosing case in a manner completely filling the case without voids and without appreciable overflow even when there is only slight clearance between the components of the enclosed device or between these components and the enclosing case.
In general, in accord with the invention, pressure filling apparatus is provided having means responsive to the movement of a fluid ejector for developing an increasing pressure to counteract the fluid ejecting pressure so that these two pressures approach but do not reach equilibrium as a container enclosing an electrical device is filled by this apparatus. The nozzle of the fluid ejector is located within a filling aperture in the container such that a continuous confined stream of fluid is produced when the fluid reaches the top thereby to generate an additional impedance or load upon the fluid ejector and immediately stop fluid flow before a build up of back pressure suiflcient to extrude fluid from any openings can occur. In this way, the fluid is first driven into the interstices of the enclosed electrical device at high speed and under high pressure until the container is almost completely filled, whereupon the speed and pressure of fluid flow gradually reduces and stops automatically as soon as the container is saturated. In addition, the greater speed of fluid injection resulting from this apparatus permits the use of a fluid consisting of a hardenable liquid insulating material having a considerably lower temperature than that permissible with gravity flow, whereby there is less shrinkage and possibility of voids during cooling and the viscosity of the liquid is greater, resulting in a lesser degree of extrusion through vents, such as lead-accommodating holes and other small openings at the joints of the case.
In accord with further features of the invention, means are provided for applying and removing the driving and counteracting pressures automatically in sequence, and for making this sequence responsive to the presentation and removal of a container to and from the nozzle whereby a succession of containers may be filled automatically. A special nozzle movable between open and closed positions is provided for this purpose.
The novel features believed to be characteristic of the invention are set forth in the appended claims. The invention itself together with further objects and advantages thereof can be easily understood by referring to the following description taken in connection with the accompanying drawing in which,
FIGURE 1 is a schematic diagram of a fluid filling apparatus embodying the invention; and
FIGURE 2 is a sectional view of a nozzle preferably employed in the apparatus of FIGURE 1.
Referring to FIGURE 1, one form of the invention is shown as comprising a nozzle assembly 1&5, and means for ejecting fluid from said nozzle assembly including a fluid ejector 11 and a fluid pump 12 preferably pneumatic, as shown. A fluorescent lamp ballast 13 having an enclosing case or container 14 is shown in position to be filled by fluid ejected from nozzle ltl. Ballast 13 is presented for filling after it has been completely manufactured except for this final potting operation. Cover plate 15, having a fluid receiving aperture 16 therein, is already fastened to the body of the case 14 and leads 17 extend through lead-accommodating apertures 18 in the ends of this case 14. Ballast 13 is supported on a movable carrier 19 which may be raised or lowered as indicated by arrow 20 to bring successive ballasts 13 into and out of engagement with the lower end of nozzle assembly 1t).
Nozzle assembly 10, best seen in FIGURE 2, comprises a base 21 and a head assembly 22 connected together by a bellows 23 surrounded by a metal jacket 29, a heating tube 29a, and a compression spring 24. Head assembly 22 has a central conical bore 25 opening into an outlet orifice or nozzle 26 surrounded by a gasket 22a. This orifice is normally covered by a plug 27 carried by an axial rod 28 attached to base 21. When head assem- J bly 22 is elevated against the force of spring 24, however, the end of head assembly 22 is moved away from plug 27 and the outlet orifice 26 is opened.
Fluid ejector 11 is connected through check valve 39 and conduit 31 to deliver fluid into nozzle assembly 1%), and is connected through another check valve 32 and conduit 33 to receive fluid in the form of hot asphalt 34 from a tank or other source of supply 35. Fluid ejector 11 comprises a fluid chamber 36 which may be T-shaped "as shown, having a piston 37 reciprocable within one cylindrical open end of chamber 36. Reciprocation of piston 37 in one direction as indicated by arrow 38 produces suction within fluid chamber 36 which causes the injection or intake of hot asphalt 34 into chamber 36 through inlet check valve 32 from tank 35 while closing outlet check valve 30. Reciprocation of piston 37 in an opposite direction, indicated by arrow 39, produces a fluid pressure Within chamber 36 closing inlet checkvalve 32 and driving any hot asphalt within fluid chamber 36 through outlet check valve 30 and conduit 31 into nozzle assembly 10.
Pneumatic pump 12 is mechanically connected to connecting rod 40 to control the operation of piston 37. Pump 12 comprises a cylindrical gas chamber 41 containing a piston 42 reciprocable within and "against the walls of chamber 41, piston 42 being attached to connecting rod 40. Gas chamber 41 has its opposite ends closed by end walls 43 and 44 whereby the chamber 41 is divided 7 by piston 42 into two pressure chambers 45 and 46' respectively. Connecting rod 40 is reciprocable through end wall 44 by means of a substantially fluid tight seal (not shown). Fluid conduits 47 and 48 open through end walls 43 and 44 into these pressure chambers 45 and 46 respectively. Piston 42 is, of course, movable in response to the difference in gas pressure within chambers 45 and 46.
A first gas or other fluid pressure for driving pistons 42 and 37 in an asphalt ejecting direction 39 of fluid ejector 11 is arranged to be delivered into pressure chamber 45 from. a suitable source of air or other gas or fluid pressure through a first regulating valve 50 and a first solenoid controlled valve 51 connected in series with one another in. conduit 47. Gas pressure for counteracting this driving pressure and for moving pistons 42 and 37 inan asphalt intake direction 38 is supplied to pressure chamber 46 through a second flow regulating valve 52 and a second solenoid actuated valve 53 in series with one another in conduit 48. Regulating valves 50 and 52 are adjusted so that the driving pressure delivered to chamber 45 is substantially greater than the counteracting fluid pressure delivered to chamber 46 of pump 12.
Solenoid valve 51 is controlled by its solenoid 55 to open when the solenoid 55 is energized and to close and vent on its outlet side when the solenoid 55 is de-energized. Solenoid valve 53, however, is of the type having one solenoid 56 which opens valve 53 when energized and a second solenoid 57 which closes and vents valve 53 on the outlet side when this second solenoid 57 is energized. Solenoids 55, 56 and 57 are respectively electrically connected to be energized by three limit switches 58, 59 and 60. As can be seen from the circuit connections of FIG- URE 1, limit switch 58 is connected in series with solenoid 55 across a source S of suitable voltage; limit switch 59 is connected in series with solenoid 56 across electric voltage source S; while limit switch 6% is connected in series with solenoid 57 across source S. Limit switch 58 is located to be actuated when the orifice 26 of nozzle is opened by the elevation of head assembly 22. Limit switch S8 is thus responsive to the presentation and removal of a ballast 13 to and from the nozzle. Limit switches 59 and 6% are arranged on opposite sides of a blade 62 rigidly fastened to connecting rod 40. Limit switch 59 is arranged to be actuated by blade 62 near the end of the driving stroke of piston 42 while limit switch 69 is arranged to be actuated by blade 62 near the end of its return stroke. The position of switch 59 relative to that of blade 62 is preferably made adjustable for a purpose to be explained. It will thus be seen that the operation of limit switches 59 and 60 and their associated solenoids 56 and 57 are responsive to predetermined positions in the cyclical movement of piston 42.
in the operation of the pressure filling apparatus of FIGURE 1, presume piston 42 of pneumatic pump 12 at the left hand end of its cylinder 41 and presume no ballast under nozzle assembly 10. Under these conditions fluid ejector chamber 36 will be filled with hot asphalt but no asphalt will flow from nozzle assembly 10 since the nozzle 26 will be closed as the head assembly 22 is depressed against plug 27 by compression spring 24. Limit switch 58 will be open whereby solenoid 55 is de-energized and valve 51 is closed and vented. Limit switch 59 will be open and limit switch 60 will be closed whereby solenoid 56 will be de-energized and solenoid 57 energized to close and vent valve 53. When a ballast 13 is placed. on carrier 19 and elevated, the ballast first engages gasket 22a of nozzle head assembly 22 with its filling aperture 16 registering with the outlet nozzle or orifice 26, and upon continued elevation, nozzle head assembly 22 is retracted away from plug 27 both to open orifice 26 and close limit switch 58. The closure of limit switch 58 energizes solenoid 55 and opens valve 51 to admit regulated driving gas pressure into pressure chamber of pump 12. Since pressure chamber 46 is vented through valve 53, the piston 42 is driven rapidly toward the right hand end of pump 12 under the influence of this driving gas pressure. Piston 37 of fluid ejector 11 is correspondingly driven at a high rate of speed to eject the hot liquid asphalt 34 through check valve 30 and nozzle assembly 10 into ballast '13. This high pressure injection of fluid into the ballast container continues during the major portion of the piston stroke until the ballast is almost full whereupon blade 62 engages the operating arm of limit switch 59. The closure of limit switch 59 completes the circuit to energize solenoid 56 and open valve 53 whereupon a counteracting gas pressure is supplied into chamber 46 of pump 12 through regulating valve 52 and conduit 48. This counteracting gas pressure automatically increases as piston 42 continues to drive forward under the influence of inertia and of the 5 driving gas pressure in chamber 45 and is adjusted by means of regulating valve 52 to approach but not quite reach equilibrium at the time the ballast container 14 becomes completely full. It will be appreciated that the point of introduction of this counteracting gas pressure during the driving stroke can be adjusted by varying the position of limit switch 59 relative to that of actuating blade 62. Once the ballast 13 becomes completely full, the increased load upon the fluid ejector 11 resulting from the increased impedance upon and confinement of the fluid stream has been found to be sufficient to stop completely the movement of piston 42 and thereby to stop the further flow of fluid from nozzle assembly 10.
Carrier 20 is then lowered permitting nozzle head assembly 22 to move downward first to open limit switch 58, and subsequently to close the nozzle or orifice 26 as the ballast moves out of engagement with the head 22. When limit switch 58 opens, solenoid is de-energized thereby closing and venting valve 51 so that piston 42 is driven to the left on a return stroke under the influence of the gas pressure still existing in gas chamber 46. During this return stroke, piston 37 of fluid ejector 11 injects a fresh supply of hot asphalt into the fluid ejector 11. Also, during this return stroke, limit switch 59 is opened and limit switch is closed by the leftward movement of actuating blade 62. The closure of limit switch 6%} at the end of the return stroke energizes solenoid 57 to close and vent valve 53 and prepare the pump for the next operation. A succession of ballasts may thus be filled automatically by merely presenting and removing them in succession to and from nozzle assembly by means of carrier 19. It will be appreciated that because of the high pressure injection of the hot asphalt into the ballast during the initial portion of the driving stroke, the possibility of voids is virtually eliminated and relatively low temperature asphalt of high viscosity may be used.
As an example of my invention, ballasts having a flow clearance between enclosed electrical device and case of less than 3' inch have been successfully filled by the above described apparatus using an asphalt filled with 53% silica maintained at a temperature of approximately 180 C. and using a driving air pressure regulated by valve 50 at 95 lbs/sq. inch and a counteracting air pressure regulated by valve 53 at 60 lbs/sq. inch introduced after the ballast was filled 90% of its complete charge.
Although I have described my invention in connection with hot asphalt, other fluids, especially liquids whose viscosity decreases with temperature increases, may be employed. It will also be appreciated that although I have shown only one embodiment of my invention, many modifications may be made, and I intend by the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.
What I claim as new and desire to secure by Letters Patent of the United States is:
1. Apparatus for fluid filling of containers comprising a nozzle, means movable in response to a first driving pressure for initially ejecting fluid from said nozzle at a first rate of flow, means responsive to the movement of said ejecting means for generating an increasing counteracting pressure on said ejecting means to reduce gradually the rate of flow from said nozzle, said driving and counteracting pressures approaching equilibrium after a predetermined volume of fluid flow, and means for additionally appyling to said ejecting means the back pressure generated by impedance in the flow of fluid ejected by said nozzle, thereby to terminate the movement of said ejecting means and stop the flow of fluid into the container being filled.
2. For use with a substantially closed container to be filled, said container having a filling aperture and being vented, fluid filling apparatus comprising a nozzle fitting snugly within said filling aperture, means movable in response to a first driving pressure for initially ejecting fluid from said nozzle at a first rate of flow, means responsive to the movement of said ejecting means for generating an increasing counteracting pressure on said ejecting means to reduce gradually the rate of flow from said nozzle and means for additionally applying to said ejecting means the fluid pressure built-up within said container thereby to arrest the movement of said ejecting means and stop the flow of fluid from said nozzle.
3. Apparatus for fluid filling of containers comprising a nozzle, pneumatic means including a reciprocable piston, means connected to said piston for ejecting fluid from said nozzle at a rate of flow dependent upon the speed of motion of said piston during its stroke in one direction, means for introducing a driving air pressure on one side of said piston to initiate a stroke of said piston in said one direction, means responsive to the motion of said piston during said stroke for introducing a counteracting air pressure on the other side of said piston, said counteracting air pressure increasing as said stroke continues to reduce gradually the speed of motion of said piston toward the end of said stroke.
4. Apparatus for fluid filling of containers comprising a movable nozzle, means movable in response to fluid pressure for ejecting fluid from said nozzle, means responsive to the movement of said nozzle for delivering a first driving fluid pressure to said fluid ejecting means, and means responsive to the movement of said ejecting means automatically introducing a second fluid pressure to said ejecting means counteracting said first fluid pressure to reduce gradually the rate of flow of fluid ejected from said nozzle.
5. Apparatus for fluid filling of containers comprising a nozzle, means movable in response to a first driving fluid pressure for ejecting fluid from said nozzle, a limit switch arranged to be operated by said fluid ejecting means during its movement, means including a solenoid valve energized by the operation of said limit switch for delivering a second fluid pressure into said fluid ejecting means in a direction counteracting said driving fluid pressure to gradually reduce the movement of said fluid ejecting means and the ejection of fluid from said nozzle.
6. Apparatus for fluid filling of enclosed electrical devices comprising a nozzle, a fiuid chamber connected to said nozzle and having a first reciprocable piston for ejecting fluid from said nozzle, a gas chamber having a second reciprocable mechanical piston mechanically connected to said first piston, means for delivering gas under a first pressure into said gas chamber on one side of said second piston to initiate a stroke of said first piston, a limit switch arranged to be operated by said pistons during said stroke, and means including a solenoid valve energized by the operation of said limit switch for delivering gas under a second gas pressure into said gas chamber on the other side of said second piston at a pressure less than said first pressure, said second pressure increasing as said stroke progresses and functioning together with the fluid load on said first piston to arrest said stroke of said pistons.
7. Apparatus for fluid filling of containers comprising a nozzle movable between open and closed positions, a fluid chamber opening into said nozzle and having a first reciprocable piston for injecting fluid into said chamber upon movement in one direction and for ejecting fluid out of said chamber into said nozzle during movement in an opposite direction, and means including a pneumatic pump for reciprocating said piston in response to the movement of said nozzle between its open and closed positions, said last mentioned means moving said piston a single stroke in said one direction in response to the movement of said nozzle to said closed position, and moving said piston a single stroke in said opposite direction in response to the movement of said nozzle to said open position.
8. Apparatus for fluid filling of containers comprising a nozzle movable between open and closed position, a fluid chamber opening into said nozzle and having a reciprocable piston for injecting fluid into said chamber upon movement in one direction and for ejecting fluid out of said chamber into said nozzle during movement in an opposite direction, a pneumatic pump connected to operate said piston, solenoid valve means for controlling the operation of said pneumatic pump, and limit switch means responsive to the movement of said nozzle for energizing and de-energizing said solenoid valve means.
9. Apparatus for fluid filling of containers comprising a nozzle movable between open and closed positions, a fluid chamber opening into said nozzle and having a first reciprocable piston for ejecting fiuid out of said chamber into said nozzle upon movement in one direction and for injecting into said chamber upon movement in an opposite direction, a gas chamber having a second reciprocable piston mechanically connected to said first piston, means for delivering gas under a first pressure into said gas chamber on one side of said second piston to drive said first piston in said one direction, means for delivering gas under a second pressure into said gas chamber on the other side of said piston during its movement in said one direction, and means responsive to the closing movement of said nozzle for venting said gas chamber on said one side of said second piston.
10. Apparatus for fluid filling of containers comprising a nozzle movable between open and closed positions, a fluid chamber opening into said nozzle and having a first reciprocable piston for ejecting fluid out of said chamber into said nozzle upon movement in one direction and for injecting fluid into said chamber upon movement in an '5 opposite direction, a gas chamber having a second reciprocable piston mechanically connected to said first piston, means responsive to the opening movement of said nozzle for delivering gas under a first pressure intosaid gas chamber on one side of said second piston to drive said first piston in said one direction, means responsive to the movement of said pistons during its stroke in said one direction for delivering gas under a. second pressure less than said first pressure into said gas chamber on the other side of said second piston, and means responsive to a closing movement of said nozzle for vent- References Cited in the file of this patent UNITED STATES PATENTS 1,586,770 Badoux et a1 June 1, 1926 2,096,499 Mandell Oct. 19, 1937 2,613,023 Reich Oct. 7, 1952 2,661,885 McBean Dec. 8, 1953 2,689,075 Morton et a1 Sept. 14, 1954