US3620649A

US3620649A - Metering pump

Info

Publication number: US3620649A
Application number: US73360A
Authority: US
Inventors: Francis H Cary
Original assignee: General Signal Corp
Current assignee: SPX Corp
Priority date: 1970-09-18
Filing date: 1970-09-18
Publication date: 1971-11-16
Anticipated expiration: 1988-11-16

Abstract

The disclosure concerns a metering pump of the type in which a primary hydraulic pump pulses a diaphragm which serves as a pumping unit for a secondary circuit. The primary unit is so constructed that its maximum rate of delivery can be changed in the field by substitution of a few parts and without using special tools or emptying the reservoir for the primary circuit.

Description

United States Patent [56] References Cited UNITED STATES PATENTS 2,945,444 7/1960 Leissner 417/269 3,285,182 11/1966 Pinkerton... 417/395 X Primary Examiner-Robert M. Walker Attorney-Dodge & Ostmann ABSTRACT: The disclosure concerns a metering pump of the type in which a primary hydraulic pump pulses a diaphragm which serves as a pumping unit for a secondary circuit. The primary unit is so constructed that its maximum rate of delivery can be changed in the field by substitution of a few parts and without using special tools or emptying the reservoir for the primary circuit.

PATENTEUuuv 16 Ian 3, 620 649 SHEET 1 or 3 INVENTOR FRANC IS H. CARY ATTORNEYS PATENTEDNUV 1 6 I8" SHEET 2 OF 3 INVENTOR FRANCIS H. CARY ATTORNEYS FIG. 2

PATENTEUNUV I 6 ISTI SHEET 3 OF 3 FIG. 2A

INVENTOR ATTORNEYS FIG.3

METERING PUMP BACKGROUND AND SUMMARY OF THE INVENTION Pulsator pumps are used extensively in the chemical and water and waste treatment industries to deliver liquids at precisely controlled flow rates. A popular metering pump of this kind includes a diaphragm which acts as the pumping unit for the metered or secondary liquid, and which is pulsed by a piston pump which acts upon it through a primary or operating liquid. The quantity of secondary liquid delivered during each pulsation of the diaphragm depends upon the displacement of the primary pumping unit, and many metering pumps on the market include a displacement-varying mechanism which can be adjusted during operation. However, no pump design of which I am aware provides a practical way of changing the maximum delivery rate in the field. This characteristic limits the utility of the pump and imposes considerable burdens on users whose process requirements undergo large changes during the service lives of the metering pumps.

The object of this invention is to provide an improved pulsator pump which allows the maximum delivery rate to be changed in the field without need of special tools and without the necessity for draining the primary liquid reservoir. The new pump includes a rate-setter sleeve for the primary pumping unit which extends into the pump casing from above the liquid level in the enclosed reservoir, and which coacts with a reciprocable piston to determine the length of the piston stroke during which the primary unit discharges oil to the diaphragm of the secondary pumping unit. The maximum delivery rate of the primary pumping unit depends upon the diameter of the mating sleeve and piston portions, and both the sleeve and the piston are designed to be withdrawn easily from the casing through an opening in its upper region. Therefore, changes in the maximum delivery rate can be efiected by merely substituting sleeves and pistons of different sizes. In the preferred embodiment, the portion of the piston which coacts with the rate-setter sleeve is easily detachable from the main part of the piston so that a change in maximum delivery rate requires replacement of only a portion of the piston.

BRIEF DESCRIPTION OF THE DRAWINGS The preferred embodiment of the invention is described herein with reference to the accompanying drawings in which:

FIG. 1 is a plan view of the new pulsator pump.

FIG. 2 is an enlarged sectional view taken on line 2-2 of FIG. 1.

FIG. 2A is a partial sectional view showing the piston-ratesetter sleeve combination which afiords the greatest maximum delivery rate.

FIG. 3 is a sectional view, on slightly reduced scale, taken on line 33 ofFlG. 1.

FIG. 4 is a sectional view taken on line 4-4 ofFlG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Referring to the drawings, and particularly to FIG. 2, the improved metering pump comprises an upright casing 11 which is supported by base 12 and encloses a reservoir 13 containing the operating oil for the primary pumping unit 14. Casing 11 is formed to provide a primary pumping chamber 15 which communicates with a pulsation chamber 16 at one side of the diaphragm 17 of secondary pump 18 through a plurality of transverse passages 19, and which is intersected by a pair of coaxial

vertical bores

21 and 22 which are aligned with a threaded opening 23 in the top casing wall 24. A rate-setter sleeve 25 is screwed into opening 23 and depends from wall 24 through a portion of reservoir 13 and into upper bore 21. The mating surfaces of sleeve 25 and bore 21 are sealed by an elastomeric O-ring 26.

Primary pumping unit 14 also includes a reciprocable piston 27 having a main portion 28 dimensioned to fit lower casing bore 22, and a reduced diameter, detachable upper portion 29 which fits the axial bore 31 of rate-setter sleeve 25. Detachable piston portion 29 comprises a slotted sleeve 32, a sealing ring 33 in the form of a glass-filled Teflon washer 33, and a rigid backup ring 34, the three parts 32-34 being held together and in assembled relation with main piston portion 28 by a stud bolt 35 and a pair of nuts 36 and 37. The displacement of piston 27 per inch of travel depends upon the difference between the diameters of

bores

22 and 31, since the relative sizes of these bores determines the effective radial width of the annular shoulder 38 on main piston portion 28. The bore 31 of the sleeve 25 shown in FIG. 2 has the largest permissible diameter, so obviously this combination of sleeve and piston affords the smallest maximum delivery rate. The maximum delivery rate of pumping unit 14 can be increased by using a sleeve 25 having a smaller bore 31, and by replacing parts 32-34 with counterparts sized to match the new bore 31. When the pump is assembled for the greatest maximum delivery rate, the reduced diameter upper end 39 of main piston portion 28 will fit bore 31 and serve to backup washer 33. Therefore, in this case, which is illustrated in FIG. 2A, a separate backup ring 34 is not needed.

The upper portion of sleeve bore 31 is in continuous communication with reservoir 13 through a pair of transverse passages 41 extending through the wall of sleeve 25 and located so that in all operative positions of the sleeve they are below the liquid level 42 in the reservoir. Therefore, when piston 27 moves down on its suction stroke, and washer 33 crosses the lower edge 43 of bore 31, operatingoil may flow into pumping chamber 15 through the grooves 44 in sleeve 32. During the succeeding upward or discharge stroke of piston 27, the oil displaced from chamber 15 will return to reservoir 13 until washer 33 again crosses edge 43 and reenters bore 31. Thereafter, the oil displaced from the pumping chamber will be delivered to pulsation chamber 16 through passages 19. The quantity of oil transferred from chamber 15 to chamber 16 depends upon the location of bore edge 43 along the path of travel of piston 27 and can be changed easily during operation by merely screwing sleeve 25 into or out of threaded opening 23. The capacity adjustment is facilitated by providing sleeve 25 with an Allen socket 44 in its exposed upper end, and by equipping the sleeve with a graduated disc 45 which cooperates with graduations on a stationary plug 46 to define a micrometer-type rate-adjustment device. For any given sleeve-piston combination, the delivery rate of pump 14 is a maximum when sleeve 25 is in the illustrated lowermost position, and this rate decreases progressively as the sleeve is adjusted upward.

The vertical configuration of primary pump 14 inherently encourages escape of air from pumping chamber 15, but this effect is intensified by giving sleeve 25 an inclined lower end face 47 and providing it with vent ports 48 which connect bore 31 with the airspace in reservoir 13. The reservoir 13, in turn, is vented to atmosphere through an axial passage 49 in plug 46.

Primary pump piston 27 is moved upward on its discharge stroke by a swash plate 51 located at the bottom of casing 11 and mounted to rotate about a vertical pin 52 pressed into base 12. The swash plate acts upon the spherical lower end of piston 27 through a slipper 53, and the parts are held in operative engagement by a return spring 54 which reacts between rate-setter sleeve 25 and snap ring 55 and serves to move the piston on its suction stroke. Slipper 53 contains an elongated slot 56 which fits around the flattened upper end of pin 52 so that the slipper is held captive by the pin. This arrangement limits the angular and radial movement of slipper 53 and insures that it will remain in a position where it can be picked up by piston 27 when the latter is removed from casing 11. Swash plate 51 is provided around its circumference with gear teeth 57 which mate with a pinion 58 formed at the lower end of a vertical shaft 59 journaled in bearings supported by casing 11 and base 12 (see FIG. 3). Shaft 59 is driven by an electric motor 61. attached to one side of casing 11 through a V-belt and sheave drive connection.

The secondary pumping unit 18 includes the pulsation chamber 16 and diaphragm l7, mentioned earlier, and also a pumping chamber 62 which is in free communication with the outer side of the diaphragm and is adapted to be connected with the secondary liquid circuit through duplex inlet and

discharge check valves

63 and 64, respectively. The diaphragm 17 pulses in synchronism with the movement of piston 27, thereby drawing secondary liquid into chamber 62 through check valve 63 and discharging it to the point of use through check valve 64. The quantity of liquid delivered by pump 18 per cycle of diaphragm 17 depends upon the effective displacement of primary pump 14, and thus is varied by adjustment of rate-setter sleeve 25 and has a maximum level determined by the particular sleeve piston combination used in the primary pump. In cases where the discharge line of the secondary pump can be closed during operation, damaging pressures could be developed in both of the

pumping chambers

15 and 62. in order to guard against this, the metering pump includes a relief valve 65 (see FIG. 4) which responds to the pressure in chamber 15 and serves to divert primary liquid therefrom to reservoir 13 when the pressure exceeds the permissible limit. The relief valve is inserted from the top of casing 11 in order to facilitate maintenance and adjustment of its setting.

Consideration of FIG. 2 should make evident the ease with which the maximum delivery rate of the pump can be changed. The disassembly procedure consists simply in removal of rate-setter sleeve 25, using an Allen wrench if desired, and in pulling piston 27 and spring 54 from casing 11 using a bolt threaded into the upper portion of lock nut 36. Since the opening 23 is above the liquid level 42, this removal step obviously does not require draining of reservoir 13. After the

parts

23, 27 and 54 have been removed, the upper portion 29 of piston 27 can be changed to suit the substitute ratesetter sleeve using only a wrench. Finally, the modified piston 27 and spring 54 are dropped back into place through opening 23 (it being remembered that pin 52 holds slipper 53 captive in a position which permits proper seating of the piston), and then the new sleeve 25 is screwed into opening 23 and adjusted to the desired delivery position.

I claim:

1. A metering pump having a primary hydraulic pumping unit (14) which serves to pulse a diaphragm (17) which serves a pumping unit 18) for a secondary circuit, and in which the primary pumping unit includes a. an upright casing (11), having a top wall (24) containing an opening (23), which encloses a reservoir (13) for operating liquid and defines therein a primary pumping chamber l) intersected by upper and lower bores (21, 22) aligned with said opening (23);

b. a rate-setter sleeve (25) supported by the top wall (24) and extending through said opening (23) and through a portion of the reservoir (13) into the upper bore (21 the sleeve preventing free communication between the primary pumping chamber and the reservoir (13) through the upper bore 21) and containing a bore (31) aligned with, but of smaller diameter than, the lower bore c. a primary pump piston (27) having portions (28, 29) which fit the sleeve bore (31) and the lower bore (22) and which is reciprocable therein;

d. a swash plate (51) at the bottom of the casing for moving the piston in the upward direction;

e. a spring (54) reacting between the piston (27) and the sleeve (25) and maintaining the piston in operative engagement with the swash plate;

f. first passage means (41) extending through the sleeve (25) for permitting transfer of operating fluid between the reservoir (13) and a region inside the sleeve bore (31) located above the piston (27); and

g. second passage means (44) controlled by the piston (27) and the sieeve (25) and connecting said region of the sleeve bore with the prima pumping chamber (15), said passage means being close and opened as the piston rises above and descends below, respectively, a predetermined position (43) relative to the sleeve,

h. the opening (23) in the top wall, the upper and lower bores (21, 22) and the sleeve (25) and piston (27) being dimensioned to pennit withdrawal of the sleeve and piston from the casing through the opening.

2. A metering pump as defined in claim 1 in which said opening (23) and a portion of the sleeve 25 are in threaded engagement, whereby the position of the sleeve (25) relative to the casing (11) can be adjusted.

3. A metering pump as defined in claim 1 in which the upper portion (29) of the piston (27) which fits the sleeve bore (31) is detachable from-the remaining portion (28) of the piston, whereby substitution of a sleeve (25) containing a bore 31) of different diameter requires only modifications of said upper piston portion (29).

4. A metering pump as defined in claim 3 in which said upper portion (29) of the piston comprises a. a sealing washer (33) coaxial with the remaining portion (28) of the piston and positioned so that it is moved into and out of engagement with the sleeve bore (31) as the piston reciprocates;

b. a piston sleeve (32) coaxial with and abutting the upper side of the washer and provided with longitudinal slots (44) in its outer periphery which define said second passage means;

c. threaded connecting means (35-37) extending through the piston sleeve and the washer and holding these parts in assembled relation with the remaining portion 28) of the piston; and

d. backup means (34 or 39) supporting the washer at its lower side.

5. A metering pump as defined in claim 4 in which the backup means comprises a second piston sleeve (34) clamped between the washer (33) and the remaining portion (28) of the piston by said threaded connecting means 35-37).

6. A metering pump as defined in claim 4 in which the backup means comprises a part of said remaining piston portion (28).

l t i i at

Claims

1. A metering pump having a primary hydraulic pumping unit (14) which serves to pulse a diaphragm (17) which serves a pumping unit (18) for a secondary circuit, and in which the primary pumping unit includes a. an upright casing (11), having a top wall (24) containing an opening (23), which encloses a reservoir (13) for operating liquid and defines therein a primary pumping chamber (15) intersected by upper and lower bores (21, 22) aligned with said opening (23); b. a rate-setter sleeve (25) supported by the top wall (24) and extending through said opening (23) and through a portion of the reservoir (13) into the upper bore (21), the sleeve preventing free communication between the primary pumping chamber (15) and the reservoir (13) through the upper bore (21) and containing a bore (31) aligned with, but of smaller diameter than, the lower bore (22); c. a primary pump piston (27) having portions (28, 29) which fit the sleeve bore (31) and the lower bore (22) and which is reciprocable therein; d. a swash plate (51) at the bottom of the casing for moving the piston in the upward direction; e. a spring (54) reacting between the piston (27) and the sleeve (25) and maintaining the piston in operative engagement with the swash plate; f. first passage means (41) extending through the sleeve (25) for permitting transfer of operating fluid between the reservoir (13) and a region inside the sleeve bore (31) located above the piston (27); and g. second passage means (44) controlled by the piston (27) and the sleeve (25) and connecting said region of the sleeve bore with the primary pumping chamber (15), said passage means being closed and opened as the piston rises above and descends below, respectively, a predetermined position (43) relative to the sleeve, h. the opening (23) in the top wall, the upper and lower bores (21, 22) and the sleeve (25) and piston (27) being dimensioned to permit withdrawal of the sleeve and piston from the casing through the opening.

2. A metering pump as defined in claim 1 in which said opening (23) and a portion of the sleeve (25) are in threaded engagement, whereby the position of the sleeve (25) relative to the casing (11) can be adjusted.

3. A metering pump as defined in claim 1 in which the upper portion (29) of the piston (27) which fits the sleeve bore (31) is detachable from the remaining portion (28) of the piston, whereby substitution of a sleeve (25) containing a bore (31) of different diameter requires only modifications of said upper piston portion (29).

4. A metering pump as defined in claim 3 in which said upper portion (29) of the piston comprises a. a sealing washer (33) coaxial with the remaining portion (28) of the piston and positioned so that it is moved into and out of engagement with the sleeve bore (31) as the piston reciprocates; b. a piston sleeve (32) coaxial with and abutting the upper side of the washer and provided with longitudinal slots (44) in its outer periphery which define said second passage means; c. threaded connecting means (35-37) extending through the piston sleeve and the washer and holding these parts in assembled relation with the remaining portion (28) of the piston; and d. backup means (34 or 39) supporting the washer at its lower side.

5. A metering pump as defined in claim 4 in which the backup means comprises a second piston sleeve (34) clamped between the washer (33) and the remaining portion (28) of the piston by said threaded connecting means (35-37).