US3172369A

US3172369A - Pump assembly

Info

Publication number: US3172369A
Application number: US183622A
Authority: US
Inventors: Vincent P M Ballu
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-01-02
Filing date: 1962-03-29
Publication date: 1965-03-09
Anticipated expiration: 1982-03-09
Also published as: FR81610E; GB1017453A

Description

March 9, 1965 v. P. M. BALLU 3,172,369

PUMP ASSEMBLY Filed March 29, 1962 3 Sheets-Sheet 1 IAWENTOQ Arroliuevs March 9, 1965 y. P. M. BALLU 3, 7 ,3

PUMP ASSEMBLY Filed March 29, 1962 3 Sheets-Sheet 2 lwemox March 9, 1965 v. P. M. BALLU PUMP ASSEMBLY 3 Sheets-Sheet 3 Filed March 29, 1962 United States Patent 1 Claims. (31. 103-175 This invention relates to pumping assemblies of a type that has come into use of recent years especially in the pumping of abrasive, corrosive and other deleterious fluids, and wherein a double-acting reciprocating piston assembly operates to pump the fluid from an inlet to an outlet of the pump casing by the creation of oppositely, cyclically, varying pressures in a pair of opposed pumping chambers, the ends of the double-acting piston assembly serving, on reciprocation of the assembly, to vary the pressures in said chambers by way of scaled deformable diaphragms so that no part of the rnOVing mechanism of the pump will at any time be exposed to the flow of deleterious fluid being pumped.

The objects of this invention relate to the solution of a number of practical difliculties that have been found to arise in the construction and operation of such pumps. Thus, objects of the invention are to provide an improved construction of the sealed, double-acting reciprocatory piston assembly, whereby its construction will be simplified, driving efliciency improved, efiicient lubrication facilitated. Another object is to improve the design and mounting of the flexible diaphragms used in such a pump. A further object lies in the provision, in association with a pump of the above character, of gas pressure accumulator means serving to reduce fluctuations in outlet fluid pressure over the pumping cycle. Other objects relate to the general construction of the pump assembly and its various components including the inlet and outlet valve means used therein, whereby manufacture and assembly are facilitated and made more economical, ruggedness and service life are improved, and dismantling and remounting operations are facilitated to expedite inspection and repairs. Other objects may appear from the detailed description to follow.

An exemplary embodiment of the invention will now be described for purposes of illustration but not of limitation with reference to the accompanying drawings, which are more or less simplified for purposes of clarity, and wherein:

FIG. 1 is an outer plan View of an improved doubleacting pump assembly according to the invention.

FIG. 2 is a side elevational view of the pump assembly, as seen from the left hand end of the assembly shown in FIG. 1.

FIG. 3 is a vertical section, with parts shown in elevation, and as seen generally on the line indicated by III III in FIG. 1.

FIG. 4 is a vertical section, with parts in elevation, generally on the broken line lV-IV indicated in FIG. 1 as regards the upper part of FIG. 4, and along an axial plane of the reciprocatory assembly as regards the lower part of said figure.

FIG. 5 is a fragmentary sectional view on an enlarged scale illustrating part of a flexible diaphragm according to a preferred feature of the invention, and

FIG. 6 is a separate view, on an enlarged scale, showing a modified form of the double-acting reciprocatory piston assembly, with the left side of the figure shown in section and the right half in outer elevation.

Referring to FIGS. 1 to 4, the improved pump structure comprises a casing 1 defining an inner cavity 2 having opposite aligned side openings providing bearing 3,172,369 Patented Mar. 9, 1965 surfaces 3a and 3b. The cavity 2 further has a top opening 4 provided with a sealing plug 5 which may be made of suitable plastic material. Bodily movable as a unit in sealing relationship with the side bearing surfaces 311 and 3b are a pair of similar pistons 6a and 611 having flat outer faces merging over rounded surfaces with the cylindrical side surfaces of said pistons. Both pistons are rigidly interconnected into a unitary structure by means of a spacer sleeve 11 having its opposite ends press-fitted around respective cylindrical bosses 7a and 7b projecting inwards from the inner end faces of the pistons 6a and 6b. Seated within the sleeve 11 and spaced inwardly from the side walls of it is an actuator bush 8 formed with a bore 9 in central relation with the pistons and sleeve, and having its end faces seated against the inner ends of bosses 7a and 7b. The end faces of bush 8 are formed with lubricating grooves 8a and 8b. Openings 12 formed through the top and bottom of the sleeve 11 permit the free circulation of oil filling the cavity 2 for an efficient lubrication of the mechanism therein.

The sleeve 11 is further formed with aligned

openings

13 and 14 through its sides (see FIG. 3) through which extends an eccentric intermediate portion 16 of a drive shaft 15 serving to reciprocate the piston unit. The shaft 15 is formed beyond the ends of the intermediate eccentric part 16 with journal portions of larger and smaller diameter than the intermediate portion, which journal portions are rotatably mounted in respective bearing sleeves 17 and 18 positioned in apertured

bosses

19 and 20 respectively formed in the corresponding sides of the casing 1.

Annular seals

21 and 22 serve to seal said apertures around the shaft journals. The boss 20 housing the larger-diameter journal of shaft 15 is formed as a flange having holes 23 in it for securing the pump casing to supporting structure as with bolts. The end of shaft 15 projecting beyond said flange outwardly of the casing is shown provided with a slotted type of coupling sleeve 24 for connection to a suitable motor not shown.

A pair of strong, flexible, cup-

shaped diaphragms

25a, 25b, have their rim flange portions 26a, 26b securely attached to the opposite ends of casing 1 around the piston bearing surfaces 3a, 3b in rebates 27a, 27b formed on the casing. The

diaphragms

25a, 25b are arranged to have their intermediate wall portions in engagement with the flat outer faces of pistons 6a, 6b.

The structure so far described including the casing 1 is partly surrounded by an outer casing structure including a pair of shell members 28a, 2812 having tapered flanges 29a, 29]) at the bottom thereof, adapted to engage around the

lower rebates

27a, 2% so as to contribute to retaining the

diaphragms

25a, 25b in position thereon. For assembling the

shell members

28a, 28b around the inner casing there are provided e.g. four tie-bolts 311 which extend through apertured lugs 31 of the shell members and through recesses 32 in the inner casing. In operation a film of oil is present between the outer faces of pistons 6a, 6b and the inner surfaces of the

diaphragms

25a, 25b. To complete the outer casing structure there is provided a domed cover 40 fitted over the flat top surfaces of the

shell members

28a, 28b and assembled thereon by means of bolts 54-.

Formed in each of the

shell members

28a, 28b is an inlet channel 33 and an outlet channel 34 separated by a partition Web 35 visible in FIG. 4, left. Both channels in each shell member communicate at their lower ends with the variable-pressure chamber in which the related diaphragm 251: or 25b is movable. The upper end of the inlet channel 33 in each shell member communicates with I a related one of two inlet valves such as the valve 36 shown at the right of FIG. 4, while the upper end of the outlet channel 34 in each shell member connects with a Q a related one of two outlet valves such as the valve 37 shown at the left of FIG. 4. As will be seen from this figure, the inlet valves 36 are housed in recesses 38 provided in the related shell member at the upper end of the inlet channel 33, while the outlet valves 37 are housed in recesses 39. formed in the pump cover 46. Each of the four valves includes a valve seat member 36a or 37a respectively and an overlying

perforate cup member

36b or 37b in which is movably positioned a vlve member 360 or 37c biassed against the valve seat by a spring 36d or 37d.

Overlying the inner casing 1, between the

shell members

28a and 28b, is a pressure accumulator 41 having the form of a two-part reservoir including a lower body element 41 and an upper cover element 53 between which a flexible diaphragm 43 is clamped. The under side of element 52 is formed with a concavity or depression facing the inner casing. The diaphragm 43 is in the form of a generally flat cup-like member similar to the

diaphragms

25a and 25b, and has its outer rim flange engaged in a rebate 44 formed in the under surface of the cover element 53, while the edge flange of the body element 41 is formed with another rebate 45 of rounded contour to participate in clamping the rim of the diaphragm under the action of bolts 46 (see FIGS. 1 to 3). An inflating air valve 42 (FIGS. 1 and 2) extends outwardly from the body 41 of the pressure accumulator and permits the pumping into the cavity beneath diaphragm 43 of the body of air or other gas under high pressure to inflate the diaphragm for a purpose later described.

FIG. illustrates an advantageous construction of the diaphragm 43 which may also be used in connection with the

diaphragms

25a and 25b earlier described. As shown, the rim flange of the diaphragm 43 is formed with an outer peripheral circumferential groove 43b and an inner circumferential groove 43a. The walls of each groove lie at an acute angle to each other with the apex inclined towards the outer end of the diaphragm so as to form circumferential lips 43c providing an extremely tight seal.

The pump cover 40 above the cover element 53 of the pressure accumulator defines a pair of parallel spaced

passages

48, 49 separated by a partition web 47 (see especially FIG. 3). Passage 48 is an inlet passage and terminates at each of its ends, on each side of the pump assembly, just above the related one of the two inlet valves 36. Similarly passage 49 is the outlet passage of the pump and terminates at each end just above the related one of the two outlet valves 37. Further, intake passage 48 at substantially its midpoint communicates with an inlet opening 5t) formed in the pump cover 40, while outlet passage 49 atits midpoint communicates with an outlet opening 51 formed in the pump cover 40 next the inlet opening. In addition, the outlet passage 49 communicates through a port 52 with the upper chamber in the pressure accumulator defined above diaphragm 43.

In the operation of the pump system described, it will be understood that the system actually performs as two separate pumps both taking in fluid from the common inlet 50 and both discharging into the common outlet 51. More specifically, on the shaft being driven in rotation from a motor not shown, the eccentric 16 acting on the actuator member 8 imparts reciprocation to the dual piston structure 6a-6b. Considering one side of the dual pump system, say the right side in FIG. 4, as the piston 6b covered by sealing diaphragm b recedes leftward to the retracted position shown, liquid is drawn in from inlet 50 through inlet passage 48 past the right hand inlet valve 36 and through the intake channel 33 into the variable-volume chamber adjacent diaphragm 251) on the right hand side of the pump. Then as the piston 6b advances rightward on continued rotation of shaft 15, the liquid thus drawn into the said chamber is discharged by the outgoing piston through the right-hand outlet channel 34, past the right-hand outlet valve (not shown, but

similar to the left-hand outlet valve 37), and into the outlet passage 49 and out through the outlet 51.

The operation on the left hand side of the pump system is identical to that just described, but occurs with a phase displacement as will be readily understood.

The function of the pressure accumulator 41 is to impart continuity to the pumping operation by averaging out the pressure differences over the pumping cycle. More precisely, as the liquid under pressure is being discharged through outlet passage 49 to the outlet 51, its pressure is applied by way of port 52 tothe air-inflated diaphragm 43, and since the gas below the diaphragm is compressible whereas the liquid above the diaphragm is not, the diaphragm yields elastically, compressing the body of gas beneath it. In the next half of the cycle when no liquid is being discharged under pressure from the piston through outlet passage 49, the compressed body of gas expands and gives up the pressure accumulated in it, through diaphragm 43, to the liquid; Thus a substantially continuous, pulse-free discharge outflow of liquid is obtained from the pump.

In the modified piston structure shown in F166, the sleeve 54 which corresponds in function to sleeve 11 in the first embodiment described, comprises a length of sheet metal tubing formed with perforations 55 for the free circulation of lubricating oil and holes 56 through which the drive shaft extends. Thesleeve54 is pressfitted at its ends around the bosses 57 'of the respective piston members 58. The piston members are desirably made from a light alloy. In each boss 57 there is formed a peripheral groove 59 into' which the sleeve 11 is crimped or swaged as shown at 60. The actuator member 61 is formed with the central bore 62 surrounding the eccentric portion of the drive shaft and has its ends 63 seated against thin-gauge discs 64 of hardened steel lining the inner faces of the piston members for reducing wear. After assembly of the parts just described, a cup-like capping member 65 is injection-molded over each end of the assembly from a suitable plastic material such as a polyamide (nylon). Preferably a circumferential gap 66 is provided between the larger-diameter part of the piston 58 and the adjacent end of sleeve 54, into which the plastic flows during the injection molding step to improve the bond.

The construction just described provides a substantial saving in weight and reduces machining operations, since the only parts of the structure requiring tobemachined to close tolerances are the cylindrical piston surfaces around which the sleeve ends are fitted and the flat surfaces on which the actuator vmember applies its thrust. The actuator member 61 preferably made of suitable antifriction metal operates in engagement with the hard steel surfaces of the insert discs 64, and the molded plastic caps 65 provide an excellent seal both Withthe casing bearing surfaces 3a, 3b and the diaphragms such as 25a, 25b. The provision of the plastic caps molded over the piston members eliminates close machining tolerances, since the depth of plastic liable to dimensional variations is small as compared to piston diameter.

It will be understood that various modifications may be made in the structural details illustrated and described without exceeding the scope of the invention.-

What I claim is:

1. A pumping system comprising in combinationz an inner casing formed with opposite axially aligned cylinders; a pair of opposite pistons respectively mounted for reciprocation in said cylinders, said pistons having cylindrical bosses projecting toward each other; a driver member provided with a bOre perpendicular to the! axis of said cylinders and slidably mounted between said bosses; a spacer sleeve, provided with holes registering with said bore and rigidly secured onto said bosses for interconnecting said pistons coaxially; a driving shaft mounted for rotation across said casing and passing through said holes and through said bore, said shaft being provided with an eccentric section engaging said bore; a pair of cup-shaped flexible diaphragms externally fitted onto the ends of said cylinders and engaging the outer faces of said pistons respectively; shell members fitted to said casing around said diaphragms for clamping said diaphragm around said cylinders and defining variable pressure chambers on each side of said casing; an outer casing provided with a fluid inlet and outlet and fitted to said shell members and valve means interposed between said outer casing and said shell members for connecting said chambers to said fluid inlet and outlet, whereby a fluid may be pumped by the system on actuation of said driving shaft.

2. The combination of claim 1 wherein said outer casing is provided with a depression facing said inner casing and with a port allowing a communication between said depression and said fluid outlet; a protruding circular edge surrounding said depression, a cup-shaped flexible diaphragm engaged onto said edge, a cup-shaped rigid member engaged onto said diaphragm and adapted for clamping it on said edge when said outer casing is fitted to said shell members; and valve means for introducing a gas under pressure between said diaphragm and said rigid member.

3. The combination of claim 2 wherein said inner casing is provided with an aperture facing said outer casing; an obturating member for said aperture, said obturating member abutting onto said cup-shaped rigid member when said outer casing is fitted onto said shell members.

4. The combination of claim 2 wherein said cup-shaped flexible diaphragms are provided with circumferential sealing grooves.

5. The combination of claim 1 wherein said spacer sleeve has ends press-fitted around said bosses, capshaped plastic coatings being molded over the outer surface of said pistons and an adjacent part of the ends of said spacer sleeve.

6. The combination of claim 5 wherein said pistons are provided with peripheral grooves for improving the bond between said pistons, said spacer sleeve and said cap-shaped coatings.

7. The combination of claim 5 wherein said pistons and said driver member are made out of a light metal alloy, resistant insert discs being interposed between said pistons and said driver member.

Rererences Cited by the Examiner UNITED STATES PATENTS 1,658,850 2/28 Mars 103-175 2,076,732 4/37 Kuehne 103-175 2,083,073 6/37 Loeber 103175 FOREIGN PATENTS 336,671 1/04 France. 599,933 3/48 Great Britain.

ROBERT M. WALKER, Primary Examiner.

LAWRENCE V. EFNER, Examiner.

Claims

1. A PUMPING SYSTEM COMPRISING IN COMBINATION: AN INNER CASING FORMED WITH OPPOSITE AXIALLY ALIGNED CYLINDERS; A PAIR OF OPPOSITE PISTONS RESPECTIVELY MOUNTED FOR RECIPROCATION IN SAID CYLINDERS, SAID PISTONS HAVING CYLINDRICAL BOSSES PROJECTING TOWARD EACH OTHER; A DRIVER MEMBER PROVIDED WITH A BORE PREPENDICULAR TO THE AXIS OF SAID CYLINDERS AND SLIDABLY MOUNTED BETWEEN SAID BOSSES; A SPACER SLEEVE, PROVIDED WITH HOLES REGISTERING WITH SAID BORE AND RIGIDLY SECURED ONTO SAID BOSSES FOR INTERCONNECTING SAID PISTON COAXIALLY; A DRIVING SHAFT MOUNTED FOR ROTATION ACROSS SAID CASING AND PASSING THROUGH SAID HOLES AND THROUGH SAID BORE, SAID SHAFT BEING PROVIDED WITH AN ECCENTRIC SECTION ENGAGING SAID BORE; A PAIR OF CUP-SHAPED FLEXIBLE DIAPHRAGMS EXTERNALLY FITTED ONTO THE ENDS OF SAID CYLINDERS AND ENGAGING THE OUTER FACES OF SAID PISTONS RESPECTIVELY; SHELL MEMBERS FITTED TO