Pump for transfer of liquids containing suspended solids

Abstract

A liquid transfer pump comprises a bellows-type chamber retractable and extendable by a reciprocating drive. The pump is fed by feed stock inflow controlled by a flexible tubular pinch-type valve, and propelled out of the chamber through an identical pinch-type valve. Quick pneumatic relief valves mounted directly on the pinch-type valves ensure instantaneous opening of the pinch-type valves thereby regulating liquid flow. Synchronous regulation of pump cycles is maintained by computer or microprocessor control.

Claims

1. A pump for transfer of liquids containing suspended solids comprising a flexible bellows having a liquid communicating port at one end mounted fixedly within a rigid housing and mounted at the opposite end to a plate adapted for slidable reciprocal movement within the housing, wherein said bellows is fillable with said liquids containing suspended solids via said liquid communicating port, reciprocating drive means attached to the slidable plate to effect extension and retraction of the bellows, a first flexible tubular pinch-type valve, operable by pneumatic means, connected to said communicating port of the bellows, a second flexible tubular pinch-type valve having the same operating configuration as the first valve, first and second mechanically operated quick pneumatic relief valves having inlet and exhaust ports that exhaust directly to the atmosphere, said valves mounted on said two tubular pinch-type valves respectively and connected via the actuating pneumatic port of the pneumatic quick relief valve to a pneumatic inlet port thereby activating said tubular pinch-type valve; and programmed control means for electronic timing and coordinating the operation of the pinch-type valves and reciprocating drive means.

2. The pump for transfer of liquids containing suspended solids of claim 1 wherein said reciprocating drive means is a piston shaft attached horizontally to the slidable plate of the bellows, reciprocally actuated by pneumatic pressure alternately from a pressure chamber, or by an electric motor-driven gear assembly and shaft similarly configured to provide extension and retraction movement to the bellows.

3. The pump for transfer of liquids containing suspended solids of claim 1 wherein said quick pneumatic relief valve is a membrane type valve and exhausts back pressure air upon cessation of positive pneumatic pressure being applied through the inlet port of the quick pneumatic valve resulting in instantaneous opening of the pinch-type valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view of the pump components fully assembled as they appear from the exterior.

(2) FIGS. 2 and 3 are cross-sectional views of the internal structure of pump parts, and further illustrate partially retracted (FIG. 2) and extended (FIG. 3) positions of the bellows chamber.

(3) FIGS. 4A and 4B are planar enlargements of the bellows feature in extended and retracted positions, respectively.

(4) FIGS. 5A and 5B are planar enlargements of the flexible tubular pinch-like valves in open and closed states.

(5) FIGS. 6A and 6B are cross-sectional views of the quick relief valve in closed and open positions, respectively.

(6) FIG. 7 is a cross-sectional view of an embodiment of the pump in continuous flow or dual flow configuration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(7) The conveyance of liquids containing substantial content of sedimentary suspended solids is daunting because the solids tend to settle out and adhere to internal moving parts of the pump and clog its action. In the present invention, the pump components are characterized in having smooth, even surfaces that prevent adherence or entrainment of sediment, and provides accurate volume control of the liquid being dispensed. FIG. 1 illustrates the gross exterior structures of the instant pump components. In its preferred embodiment, the pump comprises a flexible pleated bellows-type chamber 120 enclosed within a frame or housing 116, anchored at one end to a mounting plate or the wall of the frame 122, and at the other end to a plate 106 adapted for slidable reciprocal movement within the housing or frame. The pleated feature of the bellows is important for proper filling and evacuation of the chamber; a straight walled structure crimps and is not suitable. However, note that at its point of furthest extension, the bellows is straight-walled at every pump cycle preventing entrainment of sediment.

(8) The bellows-type chamber 120 is connected flowably through a manifold, generally 10, to two flexible tubular pinch-type valves 30. The configuration of the manifold 10 is not critical, provided that it connects both the pinch-type valves 30 to the bellows chamber 120. In FIG. 1, it is shown in a “T” conformation 124.

(9) A reversible or reciprocating drive means 100, attached to the end plate 106, passes through the housing or frame 116. It is preferably a pneumatic or hydraulic device having air or hydraulic fluid entry ports 114, but may be a motorized gear-driven assembly.

(10) Finally, the tubular pinch-type valves 30 are provided with physical intervention means, in this embodiment a mechanically operated pneumatic relief valve 50 to ensure rapid release of air pressure within the pinch-type valves 30. This is essential for virtually instantaneous opening of the valves 30 to maintain pumping volume at precise disbursement rates.

(11) FIGS. 2 and 3 show cross-sectional views of the pump in which the bellows-like chamber is depicted partially retracted and extended respectively. The cross-sectional view particularly reveals the structure of the preferred pneumatic or hydraulic reciprocating drive means, an air cylinder having a pressure responsive moveable disk 112 integral (as shown) to a rigid piston shaft 110. When air pressure is applied at inlet port 114, the moveable disk 112 is displaced, moving in retraction mode. Correspondingly, the slidable plate 106 attached to the rigid piston shaft 110, is displaced a commensurate distance, thereby retracting the bellows-type chamber. The opposite action occurs when pressure is applied at the other inlet on the opposite side of the moveable disk 112. The moveable disk 112 is displaced outwardly in extension mode of the bellows. It is advantageous that the inner wall of the air cylinder 100 be lubricated or lined with a material having a low frictional coefficient, so that the moveable disk moves bi-directionally with ease; but not so loose fitting as to cause a leak of air or hydraulic fluid from one air chamber to the other during forward and aft movement of piston shaft 110.

(12) The flexible bellows like chamber is secured in place at its ends by concentric fastening means 122 such as a pressure seal 125. The pleated accordion-like structure of the chamber facilitates retraction and extension thereof by having natural fold lines. Referring to FIGS. 4A and 4B, the structure of the pleated chamber is shown in greater detail. The pleat has an apex 106 and a sloping portion 104. When the pleat is compressed the distance between the folds decreases. At full compression the sloping portions 104 merge with liquid therebetween being squeezed into the chamber. Sediment has no structure upon which to be deposited; and plugging is prevented. Thus, there are two points in the pumping cycle, namely, at the point of full extension (a straight wall) and at the point of full retraction when retention of a solids residue is obviated

(13) FIGS. 5A and 5B are enlarged views of the tubular pinch-type valve in its open and closed positions respectively. The valve comprises a housing in two parts, a body portion 32, and two end caps 34, shown threaded 49, to receive a threaded conduit, a flexible membranous liner 44, and in this embodiment a series of restraining bolts to hold the pieces together. The membrane liner 44 is shown tethered concentrically at either end at a recess groove in body portion 42. The wall of the housing has an air inlet port 30 having an aperture 48 at its center, for ingress of pressurized air and also serves as an exhaust port. When air pressure is applied, the flexible membrane stretches inwardly (FIG. 5B) until it converges at a center point 32, thus providing an effective barrier to flow of liquid within the valve. The membrane may vary in thickness 46 from the perimeter to the center to favor convergence at the center. It is significant that when the valve is open during passage of liquid, there is no moving part in the body portion or other obstruction at which sediment can collect and plug or impede flow.

(14) The electronic control means is capable of instantaneously sending a signal opening one valve and closing the other, and coordinating the pumping action of the bellows-like chamber with valve action. Typically, valve action is mediated by a solenoid valve that gives the pinch-type valves access to air pressure. Conventionally, a vent tube is run from the pinch-type valve to one of the solenoid stations vented to atmosphere, thus relieving pressure within the tubular chamber, and opening the valve. It was discovered empirically that venting by this method is too slow, so there is delay (however momentary) in opening a valve. This means that on the inlet side, the pump “times out” before the bellows is completely filled; and on the outlet side, the bellows is pumping against a closed circuit. The result is starving the flow of liquid to its destination. The computer notes a liquid volume greater than has actually been delivered.

(15) It was found that a quick relief valve mounted on the pinch-type valve solves this problem in addition to inclusion of limit switches as described above. FIGS. 6A and 6B illustrate the quick relief valve of the preferred embodiment, although many other valve configurations may be available commercially and more or less be substituted for this particular one. FIGS. 6A and 6B illustrate a quick release valve (generally 50) having essentially two chambers separated by a moveable membrane 57. FIG. 6A shows the valve in closed position. The valve is contained within a housing 52. A source of pressurized air is connected flowably to an entry port 60 and flows through an aperture 55 into a left chamber. Air is then directed through a duckbill valve 54 into an upper chamber, which vents through an upper port 53 to a right upper chamber. The entry port 60 circular conduit passing through the center, the top portion (above the moveable membrane 57) serving as an exhaust port. An exit port 56 is flowably connected directly to the inlet port 30 at its aperture 48. While a short conduit separating the quick relief valve from its corresponding pinch-type valve is shown in FIGS. 2 and 3, to emphasize the flow pattern, it is desirable to mount the quick relief valve directly on the body of the pinch-type valve to minimize the distance exhaust air must flow to open the valve.

(16) In operation, the quick relief valve receives and transmits pressurized air to a pinch-type valve, thereby closing it. The air pressure also deflects the flexible moveable membrane 57 to form a sealing engagement of the membrane against the upper portion of the entry port 56, thereby blocking escape of air to the exhaust portion of the conduit. When air pressure ceases, the back pressure of air already contained in the pinch-type valve closes it, deflects the membrane downward to allow air to escape through the exit portion of the entry port 56. Thus, the opening of the valve is physically and functionally defined independently of computer timing instructions. This has a profound and somewhat surprising effect on normalizing flow volume between pump cycles. In combination especially with the limit switch feature, it virtually eliminates all aberrant flow.

(17) Although the pump of the present invention is primarily intended for discontinuous intermittent pumping cycles, the pump can be configured to deliver substantially continuous flow by combining two such units into a solitary device, as shown in FIG. 7. The two units face each other in presenting the bellow-type chamber apparatus, and share a common reciprocating drive means. All parts are identical and conform to drawing previously presented herein. The difference is that the drive means is adapted to bi-directional movement by extending the rigid piston shaft 102 so that it engages and is attached to the slidable plate of the bellows-like chamber of both units. In addition to providing substantially continuous pumping of identical feedstocks into a common transfer conduit, this device has the following additional advantages: (1) it allows two different feed stocks to be combined; (2) while the length of the pump stroke is fixed, the diameter is not, and therefore different proportions of two different feed stocks can be admixed; and (3) using the same integrated reciprocating drive means for two different pumps allows diversion of the two exit streams to different destinations.