Title:
A SEALING DEVICE FOR INTRODUCTION OF A VERTICAL ROTARY SHAFT THROUGH AN UPPER WALL OF A CONTAINER OR PIPE
United States Patent 3700246


Abstract:
A sealing device for introduction of a vertical rotary shaft through an opening in an upper wall of a container or pipe filled with liquid under pressure, the purpose being to prevent the liquid from contact with a packing box supporting the shaft above said wall. A vessel surrounding a shaft portion below the packing box has a bottom opening coinciding with the opening in said upper wall and dimensioned to receive the shaft with clearance. The upper part of the vessel communicates with a source of pressurized gas through a throttle valve, and a diaphragm inserted in the bottom wall of the vessel is adapted to cause the valve to open for supply of gas when liquid from the underlying container rises above a predetermined level in the vessel.



Inventors:
ENARSSON KNUT
Application Number:
05/115560
Publication Date:
10/24/1972
Filing Date:
02/16/1971
Assignee:
AB. KALLE-REGULATORER
Primary Class:
Other Classes:
277/409, 277/513, 277/516
International Classes:
F16J15/40; (IPC1-7): F16J15/00; F16J15/40
Field of Search:
277/3,12,17,18,19,27,28,29,32,135
View Patent Images:



Primary Examiner:
Rothberg, Samuel B.
Claims:
What I claim is

1. A device for sealing around a vertical, rotary shaft extended through an opening in an upper wall of a container filled with liquid under pressure for preventing liquid contact with a shaft supporting, packing box spaced above said upper wall, comprising a substantially closed vessel surrounding a shaft portion between said packing box and said upper wall dimensioned to receive said shaft with clearance permitting said liquid to rise into the lower end of said vessel, control means including a throttle valve for connecting the upper end of said vessel with a source of pressurized gas to balance and control the level of liquid therein above said opening, diaphragm means in a bottom wall of said vessel for opening said throttle valve to supply gas when said liquid from said container rises above a predetermined level in said vessel, a closed fluid chamber in communication with said diaphragm means including a wall portion comprising a second diaphragm, a gas chamber in communication with said upper portion of said vessel and said second diaphragm, said throttle valve positioned to control the input of gas to said gas chamber from said source of pressurized gas, and linkage means interconnecting said throttle valve for actuation by said second diaphragm.

2. The sealing device of claim 1, wherein said linkage means includes an adjustable resilient member mounted to subject said second diaphragm to a predetermined bias against the fluid in said closed fluid chamber.

3. The sealing device of claim 1 including vent means in said upper portion of said vessel for relieving excessive gas pressure therein from leakage of said throttle valve.

Description:
BACKGROUND OF THE INVENTION

The invention relates to a sealing device for introduction of a vertical rotary shaft through an opening in an upper wall of a container or pipe filled with a liquid under pressure, and its purpose is to prevent the liquid from contact with a packing box which supports the shaft above said wall.

As an example, a device of the kind mentioned above may be of interest for a consistency meter in which a rotary body to be immersed in a liquid is secured to the lower end of a vertical shaft. If the liquid consists of a rather viscous slurry, its penetration into the packing box may result in an increased friction which causes a poorer accuracy of the measuring. A quite particular problem arises, if the slurry contains abrasive particles, such as slurries of china clay in ceramic industries. When such a slurry penetrates into packing boxes and bearings, it causes a rapid wear of parts movable in relation to each other. The difficulty in preventing a penetration is considerably increased, if a slurry flowing through a pipe is influenced by varying overpressures.

SUMMARY OF THE INVENTION

According to the invention the problem mentioned above has been solved by means of a substantially closed vessel surrounding a shaft portion below the packing box, said vessel having a bottom opening coinciding with the opening in the upper wall of the container etc. and dimensioned to receive the shaft with clearance. The upper part of the vessel communicates with a source of pressurized gas through a throttle valve, and a diaphragm box inserted in the bottom of the vessel is adapted to cause the valve to open for supply of gas when liquid from the underlying container rises above a predetermined level in the vessel. Thus, when the valve is opened, a higher gas pressure arises in the vessel, and in this way it is possible to ensure that the liquid never comes into contact with the packing box or bearing of the shaft.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The invention will be described in more detail with reference to the accompanying drawing which shows a vertical section through an embodiment in which for better clarity a diaphragm box pertaining to the device is shown on a considerably larger scale than the other details.

It has been assumed that it is desirable to control the consistency of a porcelain slurry flowing under pressure through a horizontal pipe 1. For this purpose, the pipe 1 is provided with a widened portion in the form of an upright cylinder 2 in which the measuring is carried out by means of a consistency meter. In the known way, this consistency meter comprises a vertical motor driven shaft 3 carrying a disk-shaped sensing member 4 at its lower end. The shaft 3 is introduced axially through the top of the cylinder 2 to such a depth that the axis of the pipe 1 extends approximately through the point of gravity of the sensing member 4.

The top of the cylinder 2 is closed by a ring 5 surrounding the shaft 3 with clearance. The upper side of the ring 5 is provided with a circumferential chute 6 which is covered by a horizontal annular diaphragm 7. The ring 5 and the diaphragm 7 form together the bottom of a cylindrical vessel 8 placed over the ring axially in alignment with the lower cylinder 2. The shaft 3 passes through the vessel 8 and is journalled in a packing box 10 which is axially mounted in a cover 9 closing the top of the vessel 8. In the known way, means 11 may be provided to permit rinsing liquid to pass the packing box 10. The clearance between the shaft 3 and the surrounding ring 5 is dimensioned such that the slurry flowing through the pipe 1 can freely pass into the vessel 8.

A diaphragm box 14 mounted outside the vessel 8 is divided into two chambers 13 and 16 by a horizontal diaphragm 15. From the lower chamber 13 a passage 12 extends to the diaphragm chamber formed by the chute 6 and its diaphragm 7. The chamber 6, the passage 12 and the chamber 13 are filled with a neutral liquid, such as a mixture of glycol and water, for example. The upper chamber 16 of the diaphragm box 14 communicates with the top of the vessel through a conduit 17.

A conduit 18 from a source of pressurized air is connected to a passageway 19 extending through the wall of the box 14 to the upper diaphragm chamber 16. The passageway 19 is controlled by a valve which consists of a cone 20 cooperating with an annular seat. The valve cone 20 has a spindle 21 directed downwardly in the chamber 16. The lower end of the valve spindle 21 rests against a lever 22 directed radially within the chamber 16. The lever 22 has one end mounted on a horizontal pivot 23 which is carried by a bracket 24 close to the cylindrical wall of the chamber 16, and the opposite end of the lever 22 rests on a vertical pin 25 projecting from the center of the diaphragm 15.

The upper wall of the diaphragm box 14 has a central bore 26 axially in alignment with a pipe socket 27 connected to the outside of said wall and threaded externally. A cup-shaped cap 28 threaded internally is screwed on the end of the pipe socket 27. A helical spring 29 inserted in the bore 26 has its lower end supported by a bracket 30 which is mounted centrally of the diaphragm 15. The bracket 30 carries a pin 31 serving as a guide for the end of the spring 29, and another pin 32 directed downwardly from the inside of the cap 28 engages the upper end of the spring 29. Obviously, by turning the threaded cap 28 it is possible to impart a greater or lesser pretension to the diaphragm 15, if required. This may be necessary inter alia because of the difference in specific gravity between the liquid in the vessel 8 and the liquid in the diaphragm chambers 6,13.

The device described operates in the following manner. When the liquid in the pipe 1 is subjected to an overpressure it rises into the vessel 8, where the liquid column causes a depression of the diaphragm 7. Thereby the diaphragm 15 in the box 14 is raised and moves the arm 22 upwards so that the valve 20 is opened to increase the air pressure in the upper diaphragm chamber 16 and thus in the vessel 8. The increased air pressure thus acting on the upper sides of both diaphragms 7,15 prevents the liquid level from rising further in the vessel 8. Some liquid may be pressed back from the vessel 8 into the pipe 1 through the clearance between the shaft 3 and the ring 5. Equilibrium has been reached when the liquid level in the vessel a is constant. The diaphragm 15 has then returned to a position in which the air valve 20 has been throttled or entirely closed. The liquid level in the vessel 8 may be adjusted by turning the screw cap 28 so that the spring 29 imparts the required pretension to the diaphragm 15.

If, for some reason, the air valve 20 should leak, e.g. due to impurities caught between the valve member and its seat, this might result in an undesirable increase of the pressure in the vessel 8. However, this risk may be avoided by a vent 33 provided on the upper part of the vessel 8 and preferably dimensioned to blow off an amount of air at least equal to that which may enter at a maximum leakage in the air valve 20. Because of the vent 33 the valve 20 must, of course, always be slightly open to compensate for the loss of air, but the amounts of air consumed in this way would cartainly be rather small.