GB1569094A

GB1569094A - Pumps

Info

Publication number: GB1569094A
Application number: GB13970/78A
Authority: GB
Original assignee: Benjamin T J F
Current assignee: Benjamin T J F
Priority date: 1978-05-26
Filing date: 1978-05-26
Publication date: 1980-06-11

Description

(54) PUMPS (71) I, T. J. F. BENJAMIN, a British Subject, of 31 Corinium Gate, Cirencester, Solos., do hereby declare the invention, for which I pray that a patent may be gran ted to me, and the method by which it is to be performed, to be particularly de scribed in and by the following state ment:- This invention relates to reciprocating pumps.

Known reciprocating pumps include double-acting piston and diaphragm pumps.

These pumps employ two actuators moun ted on a common driving shaft but the flow Cf fluid does not pass over or through the actuators. A minimum of four valves, separate from the actuators, is required and the valves operate in parallel.

Another type of double-acting pump has two actuating members which are mounted on separate shafts. The flow of fluid is in the same direction over the two actuating members.

There are also known various types of single-acting diaphragm or disc pumps Which pump in one direction of stroke only. Single-acting pumps are generally prone to mechanical imbalance and are likely to generate unwanted pulses at the outlet. One type of single-acting pump is the "State" induced flow pump which has a single diaphragm and three valves. In order to avoid imbalance two such pumps are generally used horizontally opposed to each other so that the whole unit requires two actuators, two drive shafts and a total of six valves. The actuators also act in parallel and not in series.

According to the present invention there is provided a double-acting reciprocating pump comprising a transfer chamber com mumcating with an inlet and an outlet, respective actuators between the inlet and tEsfer chamber and between the transfer ahaniber and the outlet and valve means aEowing flow'of fluid from the inlet to the transfer chamber and from the transfer haMbër to the outlet, - the actuators being mounted on a common shaft to reciprocate together and the fluid pumped passing through or past the respective actuators in series and in opposed directions.

The valves required may be mounted on or in the actuators, or by use of flexible materials the actuators may themselves act as valves. The actuators reciprocate in the same direction and so can be driven by a single shaft. There is thus provided a double-acting pump which is of simple construction and has a very small number of moving components.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which Figures 1-5 are schematic sections of pumps according to different embodiments. Figures 6 and 7 are orthogonal views of the pump of Figure 5.

Referring to Figure 1, the pump comprises a housing 1 containing two cylinders 2 and 3 provided with an inlet for fluid 4, outlet 5 and transfer ports 6 connecting the cylinders. The cylinders are provided with actuators 7 and 8, provided with piston rings to form a fluid-tight fit with the cylinders, and the actuators are rigidly connected to a shaft 9 which may be reciprocated by conventional drive means outside the housing, not shown in the drawing.

Actuators 7 and 8 are provided with respective valves 10 and 11 to allow flow of fluid through the pistons in one direction only. These valves may comprise mushroom-shaped members sliding in orifices in the actuator. Each actuator may be provided with more than one valve if desired.

This pump operates as follows. When the reciprocating shaft and actuators are moved towards the left in Figure 1, fluid is drawn into chamber Al through the inlet and valve 10 is closed by the pressure in chamber A2. Simultaneously fluid is forced from chamber A2 into chamber B1 through the transfer port. Valve 11 is opened by the pressure in chamber B1 and fluid flows into chamber B2 connected to outlet 5. During this operation the pres sure difference between B1 and B2 is small, valve 11 being open.

When the shaft and actuators subsequently move from left to right, valve 11 closes and valve 10 opens. Fluid is then expelled from chamber B2 through the outlet 5 and, as chamber B1 expands, fluid is drawn from chamber Al to chamber A2 through open valve 10 and into chamber B1, completing the operating cycle.

The embodient shown in Figure 2 is simpler in that the actuators are of flexible material and no separate valve members are required. In this case the housing 21 is provided with an inlet chamber 22, an outlet chamber 23 and a transfer chamber comprising chambers 24 and 25 connected by one or more ducts 26. Chambers 22 and 24, and chambers 23 and 25 respectively, are connected by orifices associated with flexible actuators 27 and 28 rigidly connected to shaft 29 which may be driven to reciprocate by motor means not shown in the drawings.

When the shaft moves from right to left in the drawing, actuator 27 is deformed by the pressure in chamber 24 so that its edge continues to engage the rim of the orifice, preventing fluid flowing from chamber 24 to inlet 22, but the volume of chamber 24 is reduced so that fluid is forced into chamber 25 and into the outlet chamber 23 past the actuator 28 which is deformed in a similar manner to actuator 27. As actuator 28 is on the down-stream side of its respective orifice, a gap is formed between actuators 28 and its orifice rim to allow flow of fluid.

When the shaft moves from left to right actuator 28 is again deformed but in the reverse direction, so that the volume of chamber 23 is reduced and fluid is expelled through the outlet. During this operation the edge of actuator 28 is held against the rim to prevent flow of fluid from chamber 23 to chamber 25. Simultaneously actuator 27 is deformed to allow fluid to flow from chamber 22 to chamber 24. The cycle may then be repeated.

The actuators may be of composite material. They may be shaped to give efficient sealing and long life: they are preferably tapered.

The operation of the embodiment shown in Figure 3 is similar to that of Figure 1 and similar components are identified by the same numerals. However in this case the actuators do not slide along the walls of the chambers. Instead, the interior surfaces of the chambers are flexible and the actuators are fixed to them by seals 32.

The flexible interior surfaces can then move with the actuators so that no sliding surfaces, which would require lubrication, are present.

In the embodiment of Figure 4, housing 41 contains an inlet chamber 42, an outlet chamber 43 and a transfer chamber comprising chambers 44 and 45 connected by a transfer duct 46. Chambers 42 and 44 are connected by an aperture which is blocked by a rigid or semi-rigid actuator 47 engaging a flexible rim 48 surrounding the aperture. A similar actuator 49 and rim 50 are provided separating chambers 43 and 45. The actuators are rigidly attached to shaft 51 which may be driven to reciprocate as in the preceding embodiments.

In this embodiment, when the actuators move upwardly the rim 48 is deformed upwardly but a fluid-tight seal is maintained between rim 48 and actuator 47 because of the pressure subsisting in chamber 44.

Fluid is forced from chamber 44 to chamber 45. As actuator 49 is raised a gap is formed between actuator 49 and rim 50 (which is not subject to any upward deforming force) and fluid flows from chamber 45 to discharge chamber 43.

When shaft 51 moves downwardly actuator 49 expels fluid from the chamber 43 to the outlet, the rim 50 being deformed downwardly to form a seal between chambers 43 and 45, and chamber 45 is expanded, drawing fluid from chamber 44 which is consequently at a reduced pressure. At the same time actuator 47 descends to form a gap between actuator 47 and rim 48 so that fluid can flow from inlet chamber 42 to chamber 44. This individual operating cycle may then be repeated.

The embodiment of Figure 5 operates in essentially the same manner as that of Figure 2 and like components are designated by like numerals in these Figures.

However in the embodiment of Figure 5 an inlet valve 51 and outlet valve 52 are provided: these valves may be of a conventional type known in the art. This embodiment also incorporates the driving means for shaft 29 within the casing 21.

The driving means comprises a crank 53 connected by pin 54 to the shaft, the other end of the crank being drivable to reciprocate by eccentric 55 which is rotated by shaft 56 perpendicular to shaft 29. The eccentric and crank are positioned in a hollow portion 57 surrounded by the casing and shaft 56 may be rotated by an electric motor or any other driving means, not shown in the drawing. The casing 21 is made in three portions held together by nuts and bolts 58 and separated by gaskets 59 to ensure fluid-tightness.

In all these embodiments it is necessary to provide a seal between the reciprocating shaft and the various apertures in the chamber walls through which it passes. These seals may be of a conventional type, such as sliding, flexible or diaphragm seals. The seals may be designed to provide support for the actuators and assist their alignment. The flexible diaphragms may be made of metal bonded to rubber or like flexible material so that they deform to a conical shape in operation resulting, with a suitable size and shape of chamber, in a low lost displacement volume. The positions of the seals in relation to the chambers and actuators may be calculated to vary the balance between the suction and discharge strokes.

B desired, any of these pumps may be provided with additional valves at their inlets and/or outlets (as indicated in Figure 5) to improve their compression ratio, and hence the suction capability and gas handling characteristics of the pump. The shapes of the chambers may be designed to achieve the same end.

The pumps described above have the important advantage that, by virtue of suitable dimensions of the chambers and actuators and also of their double-acting action, the rate of discharge of fluid may very uniform and the pulses commonly ob tained from reciprocating pumps are reduced or virtually eliminated.

The pumps described above may be made in a wide variety of sizes and a plurality of similar pumps may be mounted in series or in parallel as desired. Similar pumps may be mounted in opposed, radial or in-line fashion and their reciprocating shafts may, in general, be driven by the same motor means. The actuators may be mounted on one side of the motor means for the pump (as in Figures 14) or on either side (as in Figure 5). The motor means may be a pneumatic unit using a cylinder and diaphragm, a hydraulic unit using a piston or diaphragm, a crankshaft or cam driven mechanically, or an electric drive unit such as a solenoid or linear electric motor.

It is believed that the pumps described above can handle a wide variety of gases, liquids and divided solids having widely differing viscosities. The pumps are selfpriming and rapid priming from dry has been achieved at a rate of lm/second. The pumps may be provided with annular ports or pumping mixed gases and liquids or solids, the gas passing through the upper port and liquids and solids through the lower port. The ports may be of a wide variety of sizes, for example from i inch diameter to 6 inches diameter or above.

WHAT I CLAIM IS: 1. A double-acting reciprocating pump comprising a transfer chamber communicating with an inlet and an outlet, respective actuators between the inlet and transfer chamber and between the transfer chamber and the outlet and valve means allowing flow of fluid from the inlet to the transfer chamber and from the transfer chamber to the outlet, the actuators being mounted on a common shaft to reciprocate together and the fluid pumped passing through or past the respective actuators in series and in opposed directions.

2. A pump according to Claim 1, in which the actuators comprise pistons slidable in cylinders defining walls of the transfer chamber.

3. A pump according to Claim 1, in which the actuators comprise pistons fixed by fluid-tight seals to flexible material defining walls of the transfer chamber.

4. A pump according to any preceding claim, in which the valve means are valves allowing flow of fluid through the actuators.

5. A pump according to Claim 1, in which at least one of the actuators is formed of flexible material and its periphery is arranged to abut an edge of an orifice through which fluid flows, the actuator and the orifice edge together forming said valve means.

6. A pump according to Claim 1, in which at least one of the actuators is arranged to abut an edge of an orifice through which fluid flows, the edge being formed of flexible material and the actuator and the orifice edge together forming said valve means.

7. A pump according to Claim 5 or 6, in which the flexible material is rubber or a plastics material bonded to metal.

8. A pump according to any preceding claim, in which the inlet comprises an inlet chamber provided with a valve allowing flow of fluid into the inlet chamber.

9. A pump according to any preceding claim, in which the outlet comprises an outlet chamber provided with a valve allowing flow of fluid out of the outlet chamber.

10. A pump according to any preceding claim, provided with a rotatable eccentric to drive the shaft in reciprocating motion.

11. A pump according to Claim 10, in which the eccentric is connected to the shaft at a point thereon between the actuators.

12. A recpirocating pump, substantially as hereinbefore described with reference to any one of Figures 1 to 4 or Figures 5, 6 and 7 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. seals may be designed to provide support for the actuators and assist their alignment. The flexible diaphragms may be made of metal bonded to rubber or like flexible material so that they deform to a conical shape in operation resulting, with a suitable size and shape of chamber, in a low lost displacement volume. The positions of the seals in relation to the chambers and actuators may be calculated to vary the balance between the suction and discharge strokes. B desired, any of these pumps may be provided with additional valves at their inlets and/or outlets (as indicated in Figure 5) to improve their compression ratio, and hence the suction capability and gas handling characteristics of the pump. The shapes of the chambers may be designed to achieve the same end. The pumps described above have the important advantage that, by virtue of suitable dimensions of the chambers and actuators and also of their double-acting action, the rate of discharge of fluid may very uniform and the pulses commonly ob tained from reciprocating pumps are reduced or virtually eliminated. The pumps described above may be made in a wide variety of sizes and a plurality of similar pumps may be mounted in series or in parallel as desired. Similar pumps may be mounted in opposed, radial or in-line fashion and their reciprocating shafts may, in general, be driven by the same motor means. The actuators may be mounted on one side of the motor means for the pump (as in Figures 14) or on either side (as in Figure 5). The motor means may be a pneumatic unit using a cylinder and diaphragm, a hydraulic unit using a piston or diaphragm, a crankshaft or cam driven mechanically, or an electric drive unit such as a solenoid or linear electric motor. It is believed that the pumps described above can handle a wide variety of gases, liquids and divided solids having widely differing viscosities. The pumps are selfpriming and rapid priming from dry has been achieved at a rate of lm/second. The pumps may be provided with annular ports or pumping mixed gases and liquids or solids, the gas passing through the upper port and liquids and solids through the lower port. The ports may be of a wide variety of sizes, for example from i inch diameter to 6 inches diameter or above. WHAT I CLAIM IS:

1. A double-acting reciprocating pump comprising a transfer chamber communicating with an inlet and an outlet, respective actuators between the inlet and transfer chamber and between the transfer chamber and the outlet and valve means allowing flow of fluid from the inlet to the transfer chamber and from the transfer chamber to the outlet, the actuators being mounted on a common shaft to reciprocate together and the fluid pumped passing through or past the respective actuators in series and in opposed directions.