WO1991003680A1

WO1991003680A1 - Anti-contamination flow control in liquids

Info

Publication number: WO1991003680A1
Application number: PCT/AU1990/000374
Authority: WO
Inventors: Wlodzimierz Rast
Original assignee: Rast Corporation Pty. Ltd.
Priority date: 1989-09-04
Filing date: 1990-08-27
Publication date: 1991-03-21

Abstract

An anti-contamination liquid flow device in which a pair of double-acting motor units (1) are driven alternatively, but overlappingly by pressure liquid and coupled to a pair of double-acting pump units (26) which receive the liquid discharged by the motor units through an air gap (between 12 and 13) and pump the liquid to a consumer line (33), characterised by flow control valve means (8, 10; 9, 10) in valve chambers (6, 7) on the motor units (1), comprising hollow spools (8, 9) movable in the valve chambers (6, 7) by the opposite motor units (1) of the pair but controlled to alternate that overlapping of the motor units (1) without generating unbalanced pressures on the flow control spools (8, 9).

Description

This invention relates to a method of and ^'means of anti-contamination flow control in liquids and in particular it relates to apparatus of the type in which a pair of motor units are coupled to a pair of pump units, and the out flow of the motor units is taken through air gap to a fluid receiver vessel, and the input to the pump units is taken from the said vessel and is displaced by the pump units to a consumer line.

It is known to use a device of this type for supplying liquid where it must be ensured that there can be no flow back from the consumer line to the main supply line, the air gap ensuring that there can be no reverse flow through the gap as there is no flow path from the consumer line back to other than the vessel into which the fluid from the main supply is discharged by the motor units.

Certain difficulties occur in units of this type which make it necessary to arrange the units to maintain a constant pressure at the consumer line during the motor and pump unit operation and for this purpose the motor units comprise at least a pair of pistons operating in cylinders to which the fluid is alternately applied and from which the fluid is pumped to discharge through the air gap into the receiving vessel.

Similarly the pump units comprise- a pair of pistons operating in cylinders, the piston of the first motor unit being connected by a connecting rod to the piston of the first pump unit, and similarly the second piston of the motor units being connected to the second piston of the pump units.

The actuation of the pistons is controlled by valve means which are adapted to bring the pistons alternately, though overlappingly, into operation and the object of the present invention is directed principally to the provision of spool valves to control the flow to and from the cylinders of the motor units, the spool valve of the first cylinder being actuated by the operation of the second piston of the motor unit, the spool valve of the second piston of the motor unit being actuated by the piston of the first cylinder.

According to this invention the valves of the pump units can be one way valves appropriately positioned to control flow to and from the cylinders of the pump units. The spool valves are of particular shape to achieve a balanced operation to eliminate pressures which would tend to move the spool valves against their required action.

The method of anti-contamination control in liquids comprises having first and second reciprocating motor units drive first and second reciprocating pump units intermittently but overlappingly, the first and second motor units being connected respectively to the first and second pump units to drive the units, actuating the motor units to discharge liquid through an air gap to a receiving vessel and pumping this liquid from the receiving vessel by the pump units to a consumer source, both the pair of motor units and the pair of pump units including valve means, characterized by the valve means for each motor unit comprising a valve chamber having ports near each end thereof connecting to the associated cylinder, causing fluid to flow from the port near one end of the valve chamber to and from one end of the cylinder, causing fluid to flow from the port near the other end of the valve chamber to flow to and from the other end of the cylinder, reciprocating a hollow spool having enlarged ends in the chamber associated with the ports to control fluid flow, supplying pressure fluid to the valve chamber between the enlarged ends of the hollow spool, receiving fluid from the valve chamber from the space within the valve chamber which is in communication with the hollow of the spool and discharging the fluid through the air gap to the receiving vessel, the hollow spool of the first motor unit being actuated by the second motor unit near the end of each stroke of the second motor unit, and the hollow spool of the second motor unit being actuated by the first motor unit near the end of each stroke of the first motor unit.

The apparatus comprises: a first motor cylinder forming part of a first motor unit having its piston coupled by a first pump rod to a piston in a first pump cylinder forming part of a first pump unit, a second motor cylinder forming part of a second motor unit having its piston coupled by a second pump rod to a piston in a second pump cylinder forming part of a second pump unit, first valve means on the first motor cylinder to control inflow and outflow of fluid to and from the two ends of the first motor cylinder, second valve means on the second motor cylinder to control inflow and outflow of fluid to and from the two ends of the second motor cylinder, third valve means on the first and second pump cylinder to control inflow and outflow of fluid from the two ends of the first and second pump cylinders, and coupling means between the first valve means and the second piston rod, and the second valve means and the first piston rod whereby the first valve means are actuated as the second piston rod nears the end of its stroke, and the second valve means are actuated when the first piston rod nears the end of its stroke, characterized in that the first and second valve means each comprise: a valve chamber connected at one end through a first port to one end of its cylinder and at its other end through a second port to the other end of its cylinder, and in each valve chamber a hollow reciprocatable spool having enlarged ends to move over the ports to reverse flow through the ports, a fluid input port to each valve chamber medial to the first and second ports to admit pressure fluid to the valve chambers to between the enlarged ends of the hollow spools, and an outlet port in each valve chamber communicating with both ends of the valve chamber through the hollow of the hollow spool, said outlet ports discharging through an air gap into a receiving vessel from which the first and second pump cylinders draw liquid to pump the liquid to a consumer source.

Other features of the invention will be apparent from the following description which is made with reference to the illustrations to which however the invention need not necessarily be limited.

In the drawings:

FIG. 1 is a somewhat schematic sectional elevation of a unit constructed according to the preferred form of this invention. The valves being shown between the cylinders for convenience of illustrating the system,

FIG. 2 is a front elevation of a typical construction of such unit,

FIG. 3 is a transverse section showing particularly the valve actuating arrangement shown in FIG. 2, taken on line 3-3 of FIG. 2,

FIG. 4 is a plan view of FIG. 2,

FIG. 5 is an underside view of FIG. 2, taken on line 5-5 of FIG. 2, and

FIG. 6 shows how the seals for the piston rods can be arranged to float to ensure that no leakage occurs if there is any lateral displacement of the piston rods. As will be seen the motor units 1 comprise a pair of cylinders 2 and 3 having within them double acting pistons 4 and 5.

The two ends of the cylinder 2 are coupled to a valve chamber 6 while the two ends of the cylinder 3 are coupled to a valve chamber 7.

The valves comprise hollow spools 8 and 9 respectively having enlarged ends 10 which are positioned to operate in connection with ports 11 in the valve chambers to control the flow on the one hand from the mains supply to the cylinders 2 and 3 and on the other hand from the cylinders 2 and 3 to a discharge line 12 which discharges fluid from the cylinders to a receiving vessel 13.

It will be seen from the illustration that as the ports 11 enter the sides of the valve chambers 6 and 7, depending on the position of the spools 8 and 9, the ports at one or the other end will be closed to the space between the enlarged ends 10 of the spools 8 and 9 but the pressure on the enlarged ends is balanced irrespective of which port is open to it.

Similarly as the spools 8 and 9 are hollow, the spaces at the two ends of the valve chambers 6 and 7 are always in communication so that pressure fluid flowing into these spaces is balanced on the spool to again allow the spools to be freely moved.

By the arrangement referred to, each valve chamber 6 and 7 has mains fluid supplied to the chamber between the enlarged ends 10 and balance therefore is maintained irrespective of the position of the spools 8 and 9 and similarly each end of each valve chamber has the same fluid pressure due to the hollow of the spools 8 and 9.

The hollow spool 8 of the first valve chamber 6 has a control rod 14 attached to it to project from end of the valve chamber 6 and has on it a pair of stops 15 which are during operation engaged by a finger 16 connected to the piston rod 17 of the double acting piston 5 of the motor units 1 , a similar control rods 18 being secured to the spool 9 to project from the valve chamber 7 also having stops 19 on it arranged to be engaged by a lever 20 the other end of which engages a piston rod 21 projecting from the double acting piston 4 of the cylinder 2, the lever 20 being pivoted at 22 to a support to reverse the direction of actuation of the control rod 18 in relation to the movement of the piston rod 21. The liquid input supply line is designated 23.

The cylinders 24 and 25 of the pump unit 26 have within them respectively pistons 27 and 28 having the two ends of the cylinders connected by intake lines 29 to the receiving vessel 13 through non return valves 30 while the two ends are also connected through output lines 31 through non return valves 32 to the consumer line 33.

It will be noted that the piston rods of the motor units 1 are of larger diameter than the piston rods of the pump units 26 to give greater capacity to the pump units, a float valve 35 controlling flow through a balancing line 36 communicating with the consumer line 33 to regulate the level of the fluid in the receiving vessel 13.

The over-pumping by the pump pistons 27 and 28 ensures that the level in the receiving vessel 13 is maintained at all times through the float valve 35 admitting water to the receiving vessel 13 as required.

The change in volume can be achieved by a change in cylinder diameter, but the arrangement illustrated is effective in ensuring correct liquid level in the receiving vessel 13.

While the arrangement shown in FIG. 1 shows the action of the coupling between the piston rods 17 and 21 and the control rods 14 and 18, the actual arrangement of this coupling mechanism may also be achieved by coupling as shown more particularly in the cross section of FIG. 3 and in FIGS. 2, 4 and 5 where sliders are used on suitable guides to transmit the motion between the various components which actuate the spool valves 8 and 9, the assembly of this being as follows.

Referring to the preferred valve operating mechanism shown in FIGS. 2, 3, 4 and 5 the finger 16 is replaced by valve actuating member 40 which has at its centre sliders 41 movably mounted on support rods 42. At the other end of valve actuating member 40 are two stops 15 which are engaged by the piston rod 17 through member 43. The other end of valve actuating member 40 has a finger 53 engaging it to control rod 14 attached to spool 8 in the valve chamber 6 to act in a manner similar to rod 16 of FIG. 1.

The pivoted lever 20 of FIG. 1 is replaced by a pivoted lever 44 which has an intermediate pivot 45 as before, but has its one end connected by a link 46 to a slider 47 which has a finger 48 coupling it to the valve rod 18 attached to spool 9 in valve chamber 7. The other end of the pivoted lever 44 being connected by link 49 to a further slider 50 which has stops 51 at each end projecting into the path of a member 52 on piston rod 21.

The action of this is similar to the action illustrated in the embodiment of FIG. 1 but avoids the relatively long unguided linkage members 16 and 20 used in FIG. 1.

The seal illustrated in FIG. 6 is a ring seal which encircles the rod and through which the rod of the piston slides but the seal itself is in the form of an annular member which is carried sealingly in a housing in a manner such that it can move laterally in the housing, that is at right angles to the axis of the rod to which the seal is applied. The cylinders 2 and 3 have their rods 17 and 21 respectively encircled by an annular ring 56 which carries a pair of circular seals 57 which engage the rods, but the annular ring 56 floats in an annular recess 58 which has a pair of ring-like side seals 59 to prevent flow of fluid past the ring 56, the seals preferably being "O" rings.

While in the drawings the motor units are shown as having hollow spool valves and the pump units are shown as having one way valves appropriately arranged, it would be possible to also use a valve system for the pump units similar to that used for the motor units, the spool valves being suitably driven and correctly timed in relation to the function required of the pump units.

It will be realised that the valve mechanism and the operating devices whereby the valves are actuated can be varied within the spirit of this invention, the system being however arranged to have at least a pair of motor units preferably of the piston type which work intermittently with overlap to ensure a continuous output of fluid to the receiving vessel 13 and similarly the pump units are proportioned and operated generally with the motor driving units to displace a liquid from the receiving vessel during the action so that as liquid is caused to flow in the consumer line by actuation of a tap or the like, the out flow of liquid is balanced with the in flow of liquid to the motor units.

To bleed air which may be carried by the water and could be trapped in the top of the cylinders, bleed lines 61 are used between the tops of the cylinders 24 and 25 and the consumer line 33.

To aid the air flow a valve 62 is inserted in the in-and-out line 29 at each end of the pump cylinders 24 and 25 which can pass through, but close, a seat 63; but this valve is seated on a spring 64 on a valve guide 65, the length of the spring being such as to hold the valve 62 within the seat but the valve can move in either direction with water flow. The valve 62 and spring 64 cause a load to ensure air and some water to flow through the bleed line 61 to ensure that there can be no build up of air in the top of the pump cylinders 24 and 25.

Claims

1. The method of anti-contamination control in liquids wherein first and second reciprocating motor units (1) drive first and second reciprocating pump units (26) intermittently but overlappingly through piston rods (17, 21 ), said first and second motor units (1 ) being connected respectively to the first and second pump units (26) to drive the units, actuating the motor units (1 ) to discharge liquid through an air gap to a receiving vessel (13) and pumping this liquid from the receiving vessel (13) by the pump units (26) to a consumer source through a line (33), both the pair of motor units (1) and the pair of pump units (26) including valve means (6, 7, 30, 32), characterized by th£ valve means for each motor unit (1 ) comprising a valve chamber (6-7) having ports (11 ) near each end thereof connecting to the associated cylinder (2, 3) of the motor units (1 ), causing fluid to flow from the port (11 ) near one end of the valve chamber to and from one end of the cylinder (2, 3), causing fluid to flow from the port (11 ) near the other end of the valve chamber (6, 7) to flow to and from the other end of the cylinder (2, 3), reciprocating a hollow spool (8, 9) in the chamber (6, 7) and having enlarged ends (10) to control fluid flow, supplying pressure fluid to the valve chamber (6, 7) between the enlarged ends (10) of the hollow spool (8, 9), receiving fluid from the valve chamber (6, 7) from the space within the valve chamber which is in communication with the hollow of the spool (8, 9), and discharging the fluid through the air gap to the receiving vessel (13), the hollow spool (8) of the first motor unit being actuated by the piston rod (17) of the second motor unit near the end of each stroke of the second motor unit, and the hollow spool (9) of the second motor unit being actuated by the piston rod (21 ) of the first motor unit (1 ) near the end of each stroke of the motor unit.

2. The method of claim 1 wherein liquid is drawn from the receiving vessel (13) into a first end of each reciprocating pump unit (26) on a stroke through a intake line (29) and one-way valve (30) and liquid is discharged from a second end of the pump unit through an output line (31 ) and a one-way valve (32) to the consumer line (33) and, on the return stroke of each reciprocating pump unit, liquid is drawn into the second end of each reciprocating pump unit from the receiving vessel through a one-way valve (30) and liquid is discharged from the first end through a one-way valve (32) to the consumer line (33).

3. The method of claim 2 wherein the displacement capacity of the cylinders (24, 25) of the pump units (26) is greater than the displacement capacity of the cylinders (2, 3) of the motor units (1 ) and liquid discharged to the consumer line (33) is fed also to a float valve (35) in the receiving vessel (13) to maintain the level of liquid in the receiving vessel due to the greater pumping capacity of the pump units (26).

4. The method of claim 2 wherein air carried by the water is displaced from the tops of the pump cylinders (24-25) by bleed lines (61) connected from the tops of the cylinders (24-25) to the consumer line (33).

5. The method of claim 4 wherein the air flow is assisted by valves (62) in the in-and-out lines (29, 31)) connecting the pump pistons (24-25) to the consumer line (33), positioning the valves (62) in valve seats (63) in the in- and-out lines (29) by means of springs (64) to close the valve (62-63), displacing the valves (62), by liquid flow when the pistons (27-28) are actuated to allow liquid flow through the valves (62), whereby forcing air and some water through the bleed lines (61 ) due to pressure of the springs (64).

6. The anti-contamination liquid flow control device comprising: a first motor cylinder (2) forming part of a first motor unit (1) having its piston (4) coupled by a first piston rod (21) to a piston (27) in a first pump cylinder (24) forming part of a first pump unit (26), a second motor cylinder (3) forming part of a second motor unit (1 ) having its piston (5) coupled by a second piston rod (17) to a piston (28) in a second pump cylinder (25) forming part of a second pump unit (26), first valve means (6, 8, 10) on the first motor cylinder (2) to control inflow and outflow of fluid to and from the two ends of the second motor cylinder (3), second valve means (7, 9, 10) in the second motor cylinder (3) to control inflow and outflow of fluid to and from the two ends of the second motor cylinder (3), third valve means (30, 32) on the first and the second pump cylinder (24, 25) to control inflow and outflow of fluid from the two ends of the first and second pump cylinders (24, 25), and coupling means between the first valve means (6, 8, 10) and the piston rod (17) of the second piston (5), and the second valve means (7,9, 10) and the piston rod (21) of the first piston 4 whereby the first valve means (6) are actuated as the second piston rod (17) nears the end of its stroke, and the second valve means (7, 9, 10) are actuated when the first piston rod (21) nears the end of its stroke, characterized in that the first and second valve means each comprise: a valve chamber (6 or 7) connected at one end through a first port (11 ) to one end of its cylinder (2 or 3) and at its other end through a second port (11 ) to the other end of its cylinder, and in each valve chamber (6 or 7) a hollow reciprocatable spool (8 or 9) having enlarged ends (10) positioned to move over the ports to direct flow to one or the other side of the pistons, a fluid input (23) to each valve chamber (6 or 7) medial to the first and second ports to admit pressure fluid to the valve chambers to between the enlarged ends (10) of the hollow spools (8 or 9), and an outlet (12) in each valve chamber communicating with both ends of the valve chamber through tha hollow of the hollow spool (8 or 9), said outlet (12) discharging through an air gap into a receiving vessel (13) from which the first and second pump cylinders (24, 25) draw liquid to pump the liquid to a consumer line (33).

7. The anti-contamination liquid flow control device according to claim 6 wherein the first and second ports (11) are annular recesses in the valve chamber (6, 7) and include an "O" ring as sealing means on each side of each port to engage the enlarged end (10) of the spool (8 or 9).

8. The anti-contamination liquid flow control device according to claim 6 wherein each spool (8 or 9) is moved by a control rod (14 or 18) attached to the spool (8 or 9) and projecting from the valve chamber (6 or 7), a pair of stops (15, 19) on the projecting part of each control rod (14 or 18), and means projecting from the rod of each piston to between the stops so that each piston (4 or 5) operates the control valve of the other piston.

9. The anti-contamination liquid flow control device according to claim 8 wherein the means which project from the piston rod (17) of the one said motor unit (1 ) comprises a finger (16) attached to the piston rod, and the means which project from the other piston rod (21) comprise a lever (20) pivoted intermediate its ends to a fixed support with one end of the lever (20) engaging means fixed to the piston rod (21 ) and the other end in the path of the stops (19) on the associated control rod (18).

10. The anti-contamination device according to claim 6 wherein each spool (8 or 9) is moved by a control rod (14 or 18) attached to its respective spool (8 or 9) , the spool operating mechanism comprising; a first valve actuating member (40) attached to guided sliders (41) on fixed rods 42 and having at one end of the valve actuating member (40) two stops (15) which are alternately engaged by a member (43) on the piston rod (17), and on the other end of the valve actuating member (40) a finger 53 connecting it to the control rod (14) attached to the spool (8) of the valve chamber (6), whereby both ends of the valve actuating member move in similar directions, and a second valve operating member comprising a lever (44) having an intermediate pivot (45), the pivoted lever (44) having at one end a link (46) connected to a slider (47) having a finger (48) coupling it to the valve rod (18) attached to the spool (9) in the valve chamber (7), the other end of the pivoted lever (44) being connected by a link (49) to a further slider (50) having stops (51) spaced apart positioned to be engaged by a member (52) on the piston rod (21), whereby the two ends of the lever (44) move oppositely.

11. The anti-contamination liquid flow control device according to claim 10 wherein the cylinders (2, 3) of the motor units (1) are connected in axial alignment with but spaced apart from the cylinders (24, 25) of the pump unit (26) by spacer rods, and the spools (8, 9) are moved by the sliders (41 , 47) which slide on the rods and are connected by fingers (48 or 53) to the spool control rods (14 or 18).

12. The anti-contamination liquid flow control device according to claim 6 wherein the displacement capacity of the cylinders (24, 25) of the pump units (26) is greater than the displacement capacity of the cylinders (2, 3) of the motor units (1 ), and the consumer line (33) includes a float valve (35) positioned in the receiving vessel (13) and arranged to raise the fluid level in the receiving vessel from the flow to the consumer device should the level in the receiving vessel (13) fall below a selected height.

13. The anti-contamination liquid flow control device according to claim 12 wherein the displacement capacity is varied by the diameter of the piston rods (17, 21).

14. The anti-contamination liquid flow control device according to claim 6 wherein each piston (24-25) of the pump unit (26) has an air bleed line (61 ) from the top of the piston, to the consumer line (33), and the in-and-out line at each end of the cylinder (24, 25) of each pump unit (26) has a valve (62) positioned in a valve seat (63) by a spring (64) but is free to move out of the valve seat (63) by water flow in either direction, a guide (65) defining the movement of the valve (62) whereby to aid an expulsion from the top of the cylinders (24, 25) of the pump units (26).

15. The anti-contamination liquid flow control device according to claim 6 wherein the seal which encircles the piston rods (17, 21) where they enter the cylinders (2, 3) of the motor units (1) and the cylinders (24, 25) of the pump units (26) each comprise an annular ring (56) having a pair of circular seals (57) which engage the rods, the annular ring (56) floating in an annular recess in the ends of this cylinder and having a pair of ring-like seals (59) positioned to prevent flow of fluid past the ring (56).

16. The anti-contamination liquid flow control device constructed and operating substantially as described and illustrated in the accompanying drawings designated FIG. 1.

17. The anti-contamination liquid flow control device operating substantially and described and illustrated in the accompanying drawings designated FIGS. 2 to 5 inclusive.