US2578746A - Fluid pump - Google Patents

Description

Dec. 18, 1951 M. H SCHERGER ErAL 2,578,746

FLUID PUMP Filed Dec. 12, 1946 Patented Dec. 18, A1951 UNITED .STATES PATENT OFFICE VFLUID PUMP 1' Milton H.v Sch-erger` and Earl BJ Terrill, Jr., Chicago,` Ill., assignors itc Mills industries, Incorporated, Chicago, Ill., a corporation of vIllinois Application December 12, 194B, Serial N o. 715,748

. 3-Claims. (Cl. ID3-44) This invention relates to" pumps ofl thetype used for pumping -a liquid or other iiuid and more particularly to a pistonpump in "which a diaphragm is employed in conjunction with-,a body of oil or other hydraulic fluid between the piston and the diaphragm.

Anv important object of Vthe inventionis the provision in such a pump of means for controlling the quantity and conditionl of the contents ofthe hydraulic liuid chamber so'that the pump will be automatically maintained at maximum efliciency over a long period of time.

To this end provision is made for replacing any liquid that may yescape from said chamber and for eliminating any excess liquid or air `that may gain admission to the chamber, al1 -without human intervention or the necessity .of stopping the operation of the pump tocorrect any improper conditions.

A further object is to provide a pump for this purpose which is so constructed that the diaphragm will notk be subject to as much strain asin the usual diaphragm pump construction and therefore will not require frequent, if any, repair or replacement during the life of the pump.

Another object is to provide a pump without a stuiing box or rotary seal which will nevertheless handle corrosive or valuable fluids automatically without loss of such-fluids.

Other objects and advantages of theinventionwill be apparentfrom the following description and accompanying drawing in which the single view is a cross section of a'uid pump in which the principles of the invention are embodied.

In the embodiment of the invention shown in the drawing the numeral I I indicatesa crankcase, which preferably is arranged in horizontal position and is supported by anend member I2 having a horizontal portion I3 resting lupon any suitable supporting base. y

The crankcase is formedto provide acylinder I4 at one end thereof lin whichal plston'lis reciprocably mounted, 4said piston being vconnected by the usual connecting rod I6 with va crank I'I on a crank shaft I8 adaptedfto be driven'from 'any suitable source of power. The crankcase containsY a body of oil," 'lndicatedby the numeral -I 9, and` when .the crankca'seisdisposed in horizontal position, ,as shown, the bottom oil `sump side-portion lthereof will provide an in which said oil is contained.

-A pumpchamber' 2l :is provided. beyond-the.'` head of the Vpiston by-meansf" of `an .enlarged cylinder head 22 and a .cap'231 secured theretov by screws 24.

The outer face of said cylinder head or block y 22 is of concave or dished formation, as indicated at 25, and the central part thereof is in the form of a grid having openings 26 therein communieating with the space 2l in the cylinder beyond the head of the piston I5.

The inner face of the cap 23 is also of concave or dished formation, as indicated at 28, the concavity therein complementing the concavity in the cylinder head 25 so as to form a chamber of generally elliptical shape, with the opposed faces thereof sloping gradually from the peripheral portions of the cylinder head and cap, the inner faces of which are preferably at.

A diaphragm 29 made of rubber sheeting, or other suitable material, is tightly clamped between the peripheral portions of the cylinder head 22 and cap 23 by the screws 24 and extends vertically across the center of the chamber 2I when the piston is in its central position.

The space between the head of the piston I5 and the diaphragm 29 is lled with a suitable hydraulic uid, such as oil, and the space on the opposite side of the diaphragm is adapted to l receive the liquid or other fluid to be pumped.

Such fluid is drawn into the latter space through an intake pipe 3I connecting with an intake check valve 32 communicating with passages 33 extending through the cap 23 into which said check valve is screwed, or otherwise suitably attached. Said valve includes a disc 34 normally held in engagement with a valve seatV 35 by means of a spring 35, said valve disc being adapted to be unseated against the tension of said spring when a vacuum is created in the pumping chamber upon the suction stroke of the piston which draws the diaphragm to its innermost position against the face 25.

A discharge check valve 31 is provided in the cap 23 on the opposite side from the intake valve 32- and' communicates with an outlet pipe 38.

. Said discharge valve includes a valve disc 39 normally heldV against a valve seat 4I by means of aspring 42. Communication is provided between r: the pumping chamber 2I and the'valve 31 by passages 43 extending through the cap 23 and the pumped uid is forced out through said passages and said discharge valve upon the compression stroke of the piston which unseats the l valvedisc 39 in obvious manner.

each compression stroke ofk the piston, thedia- 3 phragm being actuated through the medium of the hydraulic iiuid in the space between the piston and said diaphragm.

In case of loss of hydraulic fluid from said space by leakage past the piston I5, or otherwise, the lost fluid will be replaced by fluid drawn from the oil sump in the crankcase through a conduit 44 extending from said sump to yan oil` check valve 45 which in turn communicates with the space 21 through a hole 46 extending radially through the cylinder head 22. Said oil check valve may be of the ball type with a ball 41 normally held against a seat 48 by means of a spring 49. The inner face 25 of the pump chamber limits the inward movement of the diaphragm and, in case of any shortage of hydraulic fluid in the space between the piston and the diaphragm, further movement of the piston on the suction stroke will create a vacuum in said space which will result in the unseating of the valve 41 and the drawing of suicient oil from the crankcase to completely ll the hydraulic fluid space.

Any loss of iiuid from said space can only be between the piston and the cylinder wall, in which case it will be returned to the crankcase so there will be no loss of fluid from the pumping system.

It is possible that some air or excess oil might bedrawn into the space between the piston and the diaphragm on the suction stroke of the piston under centain conditions and we provide means for bleeding olf such air or excess oil, which means will now be described.

A metering valve 5I is provided in the periphl ery of the cylinder head 22 and provides intermittent communication between the pumping chamber and the crankcase with which said valve is connected by means of a conduit 52. A passageway 53 leads from the high point in the pumping chamber 2| to a reservoir 54 formed in the cylinder head inwardly from said metering valve 5I, and an oil hole 55 extends from the space 21 in the cylinder to said reservoir.

The valve 5l comprises an outer shell 55 screwed into the cylinder head 22 and having plugs 51 and 58 screwed into the interior thereof, with packing rings 59 and 6I interposed between said'shell and plugs.

seat 63 is provided on the bottom of the outer plug 51. A passageway 64 extends through the plug 58 and the plug 51 has passageways 65 and 56 therein through which fluid may pass when permitted by the action of the valve. A central partition 51 extending horizontally between the walls of the shell 56 has passageways G8 therein and is interposed betweenvtwo valve discs 69 and 1l Vcarried on a stem4 12', which is mounted in a central opening in said partition 5 1. Said discs 69 and 1| are normally held in their lowermost position by means of a spring 13 mounted on the upper end of said stem 12 and located in a cavity 14 in the plug 51, said spring bearing against a lock nut 15 above the disc 1I. The spring thus holds the disc 59 normally in contact with the seat 62, with the disc 1| unseated.

Upon the compression stroke of the piston the valve disc 69 will be unseated and the disc 1l will be seated. Thus as one part of the lvalve opens the other is moved to closed position, and the reverse action takes place on the return stroke of the piston. On the compression stroke any air or gas collected at the top of the pump- A valve seat 62 is pro-v vided on the top of the inner plug 58 and a valve ing chamber will be forced into the space 54 and, on succeeding strokes, into the space 16 between the /two parts of the valve. If no air or gas is present in the top of the pumping chamber a small amount of oil will be bled off on. each stroke, the amount not being enough, however, to materially impair the efficiency of the Pump- J Since the-*valve disc 1I will be rapidly seated against the seat B3 only a very small amount of gas or oil (perhaps less than a drop in the case of oil) will be bled on each stroke. The continuous bleeding, however, is suicient to dispose of any air or oil that may leak past the piston or to purge any air or gas which may be present in the hydraulic uid chamber when the pump n is first put into operation.

It will now be apparent that provision has been made for automatically maintaining the proper quantity and conditionof the hydraulic fluid and for preventing undue wear on the diaphragm so that the pump will operate with high eiciency for along period of time without requiring any servicing Vor the replacement or adjustment of any of the parts. Furthermore a pump constructed as herein described' is adaptable to a wide Variety of suction and discharge pressure applications for which previous constructionsv have not been well adapted.

- The foregoing detailed description has been givenfor clearnessvof understanding only, and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible in view of the prior art.

lWe claim:

l. A pump for liquids or other fluid, comprising a cylinder, apiston reciprocably mounted in said cylinder, a crankcase containing an oil sump and having a crankshaft mounted therein operativelyyconnected with said piston, a pumping chamber beyond the head of the piston, a diaphragm mounted in a midposition in said chamber,'the space between the diaphragm and the piston being adapted to receive a hydraulic fluid and the space on the opposite side of the diaphragm being adapted to receive a fluid to be pumped, intake and Outlet passages for the pumped fluid communicating with the latter space, a one-way conduit between said hydraulic fluid space and said oil sump whereby oil may be drawn from kthe latter on the suction stroke of the piston in casey of a deciency in the quantity' of the hydraulic uid in said hydraulic uid space, and means for bleeding from said hydraulic fluid space upon the compression stroke ofsthe piston, any gas which may accumulate in said hydraulic fluid space, said last-mentioned means comprising a second conduit between the high point in said hydraulic'fluid space and said crankcase and ametering valve in said second conduitconstructed and arranged to momentarily open on such compression stroke of the piston to bleed 'a small amount of gas from such hydraulic fluid space on each such stroke.

`2. A pump for liquids or other uid, comprising a cylinder, a piston reciprocably mounted in said cylinder,.a crankcase containing an oil sump and having a crankshaft mounted therein operatively connected with said piston, a pumping chamber beyond the head of the piston, a diaphragm mounted in a midposition in said chamber, the space between the diaphragm and the piston being adapted to receive a hydraulic fluid and the space on the opposite side of the diaphragm being adapted to receive a uid to be pumped, intake and outlet passages for the pumped lluid communicating with the latter space, a one-way conduit between said hydraulic uid space and said oil sump whereby oil may be drawn from the latter on the suction stroke of the piston in case of a deficiency in thel quantity of the hydraulic fluid in said hydraulic uid space, and means for bleeding from said hydraulic fluid space upon the compression stroke of the piston, any gas which may accumulate in said hydraulic fluid space, said last-mentioned means comprising a second conduit between said hydraulic fluid space and said crankcase and a metering Valve in said second conduit, said metering valve comprising a two-seat valve adapted to momentarily open on such compression stroke of the piston to bleed a small amount of gas from the hydraulic uid space on each such stroke.

3. A pump for liquids or other fluid, comprising a cylinder, a piston reciprocably mounted in said cylinder, a crankcase containing an oil sump and having a crankshaft mounted therein operatively connected with said piston, a pumping chamber beyond the head of the piston, a diaphragm mounted in a midposition in said chamber, the space between the diaphragm and the piston being adapted to receive a hydraulic fluid and the space on the opposite side of the diaphragm being adapted to receive a iluid to be pumped, intake and outlet passages for the pumped fluid communicating with the latter space, a one-way conduit between said hydraulic fluid space and said oil sump whereby oil may be drawn from the latter on the suction stroke of the piston in case of a deciency in the quantity of the hydraulic uid in said hydraulic uid space, and means for bleeding from said hydraulic iluid space upon the compression stroke of the piston, any gas which may accumulate in said hydraulic fluid space, said last-mentioned means comprising a second conduit between said hydraulic fluid space and said crankcase and a metering valve in said second conduit, said metering valve comprising a movable element having two spaced discs thereon, and a valve block having passageways for the fluid therein, said block having two spaced valve seats adapted to be engaged by said discs, respectively, one thereof being normally seated, one of the discs being unseated when the other is seated and both discs being momentarily unseated upon the compression stroke of the piston whereby a small amount of gas will be bled through said valve upon each such stroke.

MILTON H. SCHERGER. EARL B. TERRILL, JR.

REFERENCES CITED The following references are of record in the Warren July 29, 1947

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