US1787700A - Packing for pumps - Google Patents

Description

IParental' Jan; 6, 1931 UNITED STATEs LAURENCEM, IERSONS, F CHICAGO, ILLINOIS 'Paciano Fon PUMPS Application leei August 1,` 1928. Serial No. 296,811.

vMy invention relates to improvements packings for pumps and the like, and has for one object to provide a new and improved form of packing particularly in connection 6 with or rotary reciprocating positive displacement vpumps for ice machines and the like, wherein a bellows is used as the packing medium. Another object is to provide a new and improved form of pump arrangeL ment and pump and packing bellows arrangement. Other objects will appear from time to time in the specification and claims.

My invention is illustrated more or less diagramlnatically in the accompanying drawings, wherein- A f Figure 1 is alongitudinal section through a single acting pump, showing my device, with the pump piston at one end of its stroke; Figure 2 is a similar yiew showing the piston at the other end of its stroke; y

Figure 3 is a longitudinal section through -a rotary positive displacement pump;

Figure 4 is a section along the line 4 4 of Figure 3; Figure Figure 4.

Like parts are indicated -by like characters throughout the specification vand drawings.

A is a pump cylinder closed at its bottom by a head A1. A2 is an intake passage inthe head A1 communicating with the intake pipe A1. A4 is a bleeder passage leading. from the suction chamber A2 along the axis of the pump, removed from the pump cylinder and communicating at A5 with the upper or low pressure side of the pump piston. A is a crank end head or cover lfor the piston and it carries a sleeve A'fto guide the piston rod A8. A9 is the piston carried by the piston rod and reciprocating in the cylinder. A1 is an ec centricfwhich, when rotated, drives the pump, the eccentric rod A11 riding on the eccentric and pivoted on the pump piston rod AS.

The cap-A6 is perforated as at B about the periphery so as to provide a free and unobstructed passage from the low pressure side 25 5 is a section along the line 5-5 of of the pump cylinder and piston into the spacev outside of the sleeve A7. This space is inclosed by a exible'bellows B1. This bellowsy 'is anchored at one end on the cap A? and at the other end is carried by and reciprocates with the piston rod A8, there being a gas and water tight closure at each end of the bellows, the bellows elements themselves being tight to prevent leakage. 55 Atone side of the cylinder barrel is avalve y pocket. -In it are two s ring seated intake and exhaust valves C 1, respectively. A port C2 leads from the high pressure end of the cylinder into the valve chamber adja- 00 cent the intake valve C. This intake valve C closes the port C3 leading from the suction chamber A2. The exhaust valve C1 closes the port C1 and when unseated permits discharge of fluid by the pump through the valve chamvber and through the dischargepipe C5.

Rotation of the eccentric, of course, causes reciprocation of the pump piston in the usual manner. When the pump piston is drawn -up it 'sucks fluid in through the pipe A3, chamber 70 A1, port C, lifting the intake valve C. As the plunger starts down the pressure immediately seats the intake valve C but lifts the dischargevalve C1 and fluid flows out through the' port C1 and pipe C5. Of course. 75 on the suction vstroke the valve C1 is seated by its spring. y

There must always be a certain amount of leakage between the pump and the cylinder-that is, leakage from the high pressure 3Q to the low pressure side of the piston.l Such leakage, when refrigerants such as ammonia and the like are used, is 'fatal and a positive closure must be provided to prevent thel escape of any material leaking past the plunger into the atmosphere. This is provided by the bellows. Any material which may leak past the piston will be segregated on the low pressure side thereof and in thc space inclosed within the bellows, and will be 9 0 drawn off by the bleeder pipe A comm unicating with the suction side of the pump. The presence of this bleeder passage A4 insures that the pressure o n the low pressure side of the plunger can never exceed\suction line 95.

pressures, and therefore there isno possibility of thebellows packing being compelled to stand high pump pressures. The opening and closing ofthe bellows in response to the reciprocati'on of\ the plunger may ICT' merely slightly change the volumetric capacityv of the low. pressure chamber. It is possible that the bellows may even act as a pump under some conditions and suck in fluid from the low pressure side as it goes up, and blow it back into the low pressure side as it goes down. More likely, however, the leakage will merely churn around in the spaceincluded in the low pressure side of the cylinder and the bellows, but in no event will any material be able to escape because the bellows provides a positive-` tight closure and in no case will the bellows be subjected to any pressure which would cause it unduly short life.

In the modilied forni shown in Figures 3, 4 and 5, there is shown a different type of pump. D lis a pump cylinder. In it gyratesv a propeller head D1. This propeller head does not rotate, being `held against rotation by the weber' lug D2, which is mounted to reciprocate along radial lines in a slot D3 vin the cylinder, D1v is a slee-ve upon lwhich the head D is loosely mounted. l)5 is an eccentric-carrying the sleeve D4, so that when thc eccentric is rotated the sleeve and the pump head D1 will be gyratedin the cylinder, the arrangement of the parts being such that the head always engages the inside of the cylinder along a line parallel with its axis of rotation. -As this head gyrates this line constantly travels around the periphery of the cylinder but the head itself does not rotate. Rotation of the eccentric and gyration of the head in the direction of thearrow shown in Figure 4 causes the pipe D6 to be the intake, the pipe D1 to be the exhaust, and causes Huid toVv pass around the peripheral wall of the housing from the intake to the exhaust pipe, since it cannot get straight across owing to the presence of the web D1.

The eccentric D5 is mounted on the end of a shaft E, which shaft rotates in a bearing sleeve E1'in the housing E2, being driven by a belt or any suitable means applied to the pulley E3. 'The sleeve E1 is provided with a flange E4l which is bolted to the housing E2 so as to provide a tight chamber. To prevent leakage of pump `material through or along -the bearing Aof the eccentric shaft, and to make it unnecessary to have tight packings to prevent leakage, a bellows packing is provided. This bellows takes the form of two separate bellows elements F, F1,both surrounding the sleeve E1 and the shaft E, the

bellows F being closed at one end by the web or flange E", at its otherend carrying a filler, sleeve F2 which engages and makes a closed chamber with the bellows F1, and the opposed end of the bellows F1 is anchored on the lange F3 of the sleeve D4. Any leakageof material being pumped will come along the outside of the sleeve D* into the chamber on the outside of the bellows, on the outside of the illei` sleeve, on the inside of the housing E2, and no leakage will be able to reach an of the driving or working parts, and no lea age will therefore be able to escape. In order to protect the bellows against undue pressures, a bleeder'pipe F4l leads from the inlet D8 to the space immediately outside' by the bellows is of the utmost importance,

because experience shows that reversal of pressures and excess pressures greatly decrease the effective life ofthe bellows. If the pressures can be maintained substantially constant, and if little violent reversal of pressures prevail, the bellows will stand a static load, even when vibrated as indicated, for surprisingly long periods of time.

It will be noted that the bellows in the form shown. in Figure .3 might be continuous, but it is. cheaper and more satisfactory to provide two separate bellows elements joined by a tube,as the major bending resultant upon the gyration of the plug hat shaped sleeve which carries the eccentric takes place "at the two ends and the long tube, giving a fairly long radius, reduces to the minimum the burden upon the bellows.

I claim:

1. In a pump, a housing, a reciprocating piston, a piston rod therefor, a bellows one end of which is rigidly tilted` on and closed by the housing, surrounding the piston rod, theFother end of which is rigidly mounted on and closed by the piston rod,' passages` leading from the low pressure side of the plunger to the interior of the bellows and means forlimiting the pressures developed within the bellows, said means comprising a bleeder conduit leading from the bellows to the intake side of the pump.

2. vA pump comprising a housing, a single action piston reciprocating therein, intake and discharge valves associated with the working side of the piston, a sleeve projecting from the housing, a piston rod s lidable in and guided by the sleeve, ableeder passage leading from the vinactive side of the piston to the suction line, a bellows anchored on and closed by the housing on one end, anchored on and closed by the piston rod atthe other and enclosing the piston rod and sleeve, there being bleeder ports through the wall of the housing between the interior of thebellows and the inactive side of the piston.

Signed at Chicago, county of Cook and 'State of Illinois, this 28th day of July, 1928.

LAURENCE M. PERSONS.

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