US1517902A - Stuffing box - Google Patents

Description

@am 2, i924. 1,517,902

J. C. GOOSMANN v STUFFING BOX Filed Feb. 23. 1922 Patented ec. 2, 1924.

JUSTUS C. GOOSMANN,

OF CHICAGO, ILLINOIS.

STUFFING BOX.

Application filed February 23, 1922.

T0 @ZZ whom t may concern:

Be it known that I, JUsTUs C. GoosMANN, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Stuffing Boxes, of which the following is a specification. i

This invention relates in general to stuffing boxes, and is particularly efficacious' in connection with high pressure cylinders forl the purpose of preventing leakage of gas or other iiuid, as the case may be, around the piston rod which reciprocates through one end wall of the cylinder.

In apparatus such as reciprocatory compressors for refrigerating machines for instance, it is difficult to prevent the leakage of the gaseous refrigerant around and past the reciprocating piston rod, since ordinary packings and stuffing boxes soon become sufficiently worn to permit the escape of a considerable amount of gas. I am aware that it has heretofore been proposed to overcome such leakage by maintaining a greater pressure of oil or other liquid in the stuffing box around the piston rod, but unless a very hi'ghioil pressure be maintained, the leakage will not be obviated, and if an excess oil pressure is maintained', the expense is high. and furthermore a considerable quantity of the oil will be forced around the piston rod into the cylinder upon 'the intake stroke of the piston.

One of the primary purposes of the present invention is to prevent leakage and loss of gas. or other Huid which may be used, in an apparatus of the character indicated, and to accomplish this result without maintaining a high oil pressure in the stuffing box and without loss of either oil or gas.

With this general aim in view, my invention contemplates a stufHng box provided with a plurality of channels or lanterns surrounding the piston in spaced relation, and mechanism connected with said channels which ensures the maintenance of a predetermined pressure in each channel, the pressures, 'however7 being progressively stepped down in the successive channels so that the lowest pressure is maintained in that channel most remote from the cylinder. As a result there are no abrupt pressure changes in the stuffing box, but on'the contrary, there exists a gradually decreasing pressure which serves to prevent leakage and loss of gas around the reciprocating piston rod.

Serial N0. 538,745.

For the purpose of facilitating an understanding of my invention, I have'illustrated in the accompanying drawing a preferred embodiment thereof, and in the single view, the invention is shown somewhat diagrammatically and partially in section as applied to the compressor of a refrigerating apparatus.

On the drawings, reference character 5 indicates generally the cylinder of a compressor of the double acting type, in which cylinder the piston 8 is reciprocated by means of a piston rod 9 actuated from a reciprocatory cross head 11 which in turn is driven through the connecting rod 12 from a crank 13. At its outer end the cylinder is connected with the intake pipe 14 and the delivery pipe 15, and similarly at its inner end the cylinder is connected with the intake pipe 16 and the delivery pipe 17. The two branches 14 and 16 of the intake merge into a common intake pipe 18, while the delivery branches 15 and 17 merge into the common delivery pipe 19. Suitable valves (not shown) are provided to ensure flow of gas in the proper direction through these various pipes.

The outer end of the cylinder is closed and effectively sealed by the cylinder head 21. the inner end however is necessarily open to accommodate the piston rod 9, and it is for the purpose of preventing leakage around this rod that my present invention was devised.

The stuffing box proper through which the piston rod projects may be of well known or preferred construction, but the packing employed therein is so constructed and arranged as to provide a plurality, in the present instance two, of channels or lanterns 22 and 23, surrounding the piston rod and spaced apart, substantially as shown. While a greater number of these lanterns or channels may be provided in the stuffing box, I have found that for ordinary purposes two will suffice, one located near the outer end of the stuffing box and the other about intermediate the outer lantern and the end 0f the cylinder proper.

The gas or other fluid which escapes from the cylinder around the piston rod upon the compression stroke of the piston, enters the channel or lantern 22 from which it is conducted through a pipe 24 connected with this lantern to the casing of a controlling vvalve indicated generally by reference character 25, rl`his controlling valve of the pressure reducing type and comprises a valve scat 26 disposed within the chamber 27 with which pipe 241e communicates, and a hollow valve proper 28 adapted to =close against this seat and shut ofte or limit the case may be, communication between the chamber 27 and a pipe 29 connected at one end with the controlling valve beneath the seat thereof and at its other end with the intake pipes leading to the compressor cylinder.

rllhe upper end of the chamber 2'? is closed by a flexible diaphragm 3l centrally perforated to receive the valve 28 to which it is ,sc-- curely clamped. Above the chamber 2? there is formed in the valve casing a second chamber 32, providing a simila but larger diaphragm 33 also centrally perforated to receive the valve member 28 and securely clamped thereto. Both diaphragms are clamped to seal the respective chambers at their margins. A passage 34 extending longitudinally through the valve member 28 communicates through the branches 35 with the chamber 32 above the diaphragm 83. A light expansionspring 36 is interposed between the upper end of the valve mechanism, and washers 3'? disposed in the upper end of the chamber 38, serve to normally maintain the valve 28 in seated relation againstits seat 26. The tension of this spring may be increased or diminished, if desired, by increasing or reducing` the number of washers 37 employed.

The stuffing box lantern 23 is connected by a pipe 39 with an oil pump tl of any preferred construction automatically actuated from the cross-head ll through suitable mechanism including` the oscillatory link 42, the pump and driving mechanism being so proportioned as to supply sufficient eil for tl e lubrication of the piston rod and n'laintain the lantern full of oil which will be kept under a iireeletermiued iu'essure as will be later explained 'lhe oil is delivered from the lantern 28 hrough pipe from which it is discharged into the chainliier 38 of the controlling valve from which chamber it flows through the passage 3st into the pipe 29, thence through the intake branches 14; and 16 into the cylinder to lubricate the piston 8.

lt will be manifest that the pressures in the oil lantern 23, the valve chamber 327 and in the return pipe 29, will all be equal and that the pressure in the gas` lantern 22 will be the same as that in the valve chamber 27. The diaphragms 31 and 33 are so Vproportioned that the exposed area on the upper face of diaphragm 33 is substantially twice the area of the lower exposed face 0f 'diaphragm 31. l/Vhen there is a pressure in chamber 27 equal to twice the pressure 1n chamber 32, plus the downward pressure retrasos exerted by the spring 36, the valve 28 will be exactly balanced, and if the pressure in chamber 27 rises, the valve will be correspondingly lifted from its seat to permit an escape of pressure from the chamber 27 into the passage 34 and pipe 29. lVhen the pres sure in chamber 27 has lowered, the valve will again be closed with the result that by this mechanism a substantially uniform pressure is maintained in the lantern approximately twicek as great as the pressure which will be maintained in the lantern For the purpose of determining the amount of pressure in the lantern 22, the pipe 211- is preferably equipped with a pressure gage 4A.

ln the operation of my invention, assuming that the machine is designed to maintain an intake pressure leading` to the cylinder of twenty-two atmospheres and a compres sion pressure in the cylinder and the discharge pipes leading therefrom of sixty# sin atmospheres, the controlling valve will maintain a pressure in the intermediate lantern 22 of forty-four atmospheres. As the piston 8 reciprocates, it will upon its compression stroke toward the left, viewing the drawing, cause some of the gas being compressed to escape around the piston rod at a pressure of sixty-six atmospheres. This escaping pressure will be opposed by a lesser pressure of forty-four atmospheres maintained in the lantern and in the pipe 24 by the controlling` valve and when the pressure in this lantern and pipe rises above fortyfour atmospheresS the valve 28 will be opened suliiciently to permit the escape of this pressure into the pipe 29, whence the gas is returned to the cylinder. Leakage outwardly along the piston rod from the lantern 22 `is opposed by an oil pressure of twenty-two atmospheres maintained in the lantern 23, and the surplus oil delivered to this lauternin addition to that required for piston rod lubrication purposes 'is returned through pipe 43, the controlling valve and the pipe 29 to the intake pipes leading to the cylinder where the oil is employed for lubricating the piston 8. lt will be apparent, therefore, that there is a gradual step down or reduction in pressure around the piston rod, which not only obviates the employment of high oil pressure in the stuffing box and consequent leakage and oil losses resulting therefromr` but it also prevents the direct leakage and escape of gas from the cylinder and such gas as will inevitably leali` into the stufing box is also returned to the cylinder and retained within the apparatus.

lt is believed that my invention and many of its inherent advantages will be understood and appreciated from the foref ;oing` without further description, and it should be obvious that the structural details shown and described may be' varied Within wide gill limits without departing from the essence of the invention as deiined in the following claims.

claim:

l. The combination of a compression cylinder, a piston operating therein, a stuffing box surrounding the piston rod and provided with an inner and an outer annular channel surrounding said rod, means for maintaining a predetermined pressure in the inner channel, and a predetermined but lower pressure in the outer channel, and a pipe :tor delivering gas leakage trom both channels together with lubricating oil to said cylinder.

2. The combination of a compression cylinder, a piston operating therein, a stuifing box surrounding the pist-on rod and having a plurality of annular channels surrounding the rod, means Jfor establishing continuous communication between the outer one of said channels and the suction side of said cylinder, means for supplying lubricant under pressure to said channel against the pressure existing in the cylinder intake, and a pressure controlling valve connected with the other of said channels and adapted when the pressure in said last mentioned channel exceeds by a predetermined amount the intake pressure of said cylinder, to establish communication between said second channel and the intake of said cylinder.

3. The combination of a compression cylinder, a piston operating therein, a stuffing box surrounding the piston rod, inner and outer channels around said rod, a pipe leading from the suction side of said cylinder, means for establishing communication between said pipe and the inner one of said channels when the pressure in said channel exceeds by a predetermined amount the pressure in said pipe, whereby a predetermined ratio of pressures between the suction side of said cylinder and said channel is maintained, means for establishing continuous communication between said pipe and the outer one oi said channels, and means for supplying lubricant against the suction pressure of the cylinder to said last mentioned channel.

4. The combination of a compression cylinder, a piston operating therein, a stuffing box surrounding the piston rod and provided with an inner and an outer annular channel surrounding said rod, automatic means for maintaining a predetermined ratio of pressures in said channels, and a connection for returning pressure leakage along the piston rod from both of said channels back to said cylinder.

5. The combination of a compression cyl inder, a piston therein, a piston rod projecting from the cylinder, and al stuffing box surrounding the piston rod and provided with a plurality of annular channels, means for creating a predetermined fluid pressure in the outer one of said channels, a connection from said channel tothe intake of said cylinder through which lubricating fluid and gas leaking from the cylinder along said piston rod are delivered to the cylinder, ia valve interposed in said connection and provided with a pair of diaphragms of diiierent diameters controlling the opening and closing of the valve proper, a connection between the inner one of said channels and the valve casing through which the pressure of the inner channel is exerted upon the smaller of said diaphragms, and mea-ns co-operating with the pressure from the outer channel for urging said valve against its seat to shut oil' communication between the inner channel and the cylinder until the pressure in said inner channel exceeds by a predetermined amount the pressure in said outer channel whereupon communication between said inner channel and said cylinder is established.

JUSTUS C. GOOSMANN.

Images