NZ753080B - A Pumping System - Google Patents

Abstract

The invention relates to a pumping system for applying heat sensitive chemical liquids. It is known to use piston pumps to transfer liquid chemicals, for example to supply paint to spray equipment. The operation of some known piston pumps generates heat through friction where seals interface with cylinders or rods. It can be a problem that some chemicals, for example UV paint, are heat sensitive and so may be damaged by heat caused by the operation of the piston pump, or heat cured. The system comprises a fluid inlet, a piston pump having a piston, a first diaphragm pump having a first diaphragm and a load chamber, a second diaphragm pump having a second diaphragm and a delivery chamber, valve means, and a fluid outlet. The system is arranged such that a first stroke (for example, an upward stroke) of the piston causes the first diaphragm to create a vacuum to draw the fluid into the load chamber via the inlet, and the second diaphragm to drive the fluid from the delivery chamber via the outlet. A return stroke (for example, a downward stroke) of the piston causes the first diaphragm to drive the fluid from the load chamber into the delivery chamber, and the second diaphragm to displace the fluid from the load chamber into the delivery chamber, and the valve means opens and closes the load and delivery chambers. linders or rods. It can be a problem that some chemicals, for example UV paint, are heat sensitive and so may be damaged by heat caused by the operation of the piston pump, or heat cured. The system comprises a fluid inlet, a piston pump having a piston, a first diaphragm pump having a first diaphragm and a load chamber, a second diaphragm pump having a second diaphragm and a delivery chamber, valve means, and a fluid outlet. The system is arranged such that a first stroke (for example, an upward stroke) of the piston causes the first diaphragm to create a vacuum to draw the fluid into the load chamber via the inlet, and the second diaphragm to drive the fluid from the delivery chamber via the outlet. A return stroke (for example, a downward stroke) of the piston causes the first diaphragm to drive the fluid from the load chamber into the delivery chamber, and the second diaphragm to displace the fluid from the load chamber into the delivery chamber, and the valve means opens and closes the load and delivery chambers.

Description

TITLE A Pumping system.

FIELD OF INVENTION The invention relates to a pumping system. A preferred form of the invention relates to a system for use in applying heat sensitive chemical liquids.

BACKGROUND It is known to use piston pumps to transfer liquid chemicals, for example to supply paint to spray equipment. The operation of some known piston pumps generates heat through friction where seals interface with cylinders or rods. It can be a problem that some chemicals, for example UV paint, are heat sensitive and so may be damaged by heat caused by the operation of the piston pump, or heat cured.

OBJECT OF THE INVENTION It is an object of preferred embodiments of the invention to go at least some way towards addressing the above problem. While this applies to preferred embodiments, it should be understood that the object of the invention per se is simply to provide a useful choice.

Accordingly, any objects applicable to preferred embodiments should not be taken as a limitation on the scope of any claims expressed more broadly.

INTERPRETATION The term “comprises”, or derivatives thereof, should not be interpreted as excluding other features. For example, if used in relation to a combination of features it indicates that optionally, but not necessarily, there may be additional features that have not been mentioned.

Terms such as “upper” or “lower” when used in relation to certain items in the drawings refer to the orientation those items have in the drawings. Such terms are used for ease of explanation. However, it should be understood that when in storage or use those items may have a different orientation.

SUMMARY OF THE INVENTION According to one aspect of the invention there is provided a pumping system comprising: • a fluid inlet; • a piston pump having a piston; • a first diaphragm pump having a first diaphragm and a load chamber; • a second diaphragm pump having a second diaphragm and a delivery chamber; • valve means; and • a fluid outlet arranged such that: o a first stroke (for example, an upward stroke) of the piston causes:  the first diaphragm to create a vacuum to draw the fluid into the load chamber via the inlet; and  the second diaphragm to drive the fluid from the delivery chamber via the outlet; o a return stroke (for example, a downward stroke) of the piston causes:  the first diaphragm to drive the fluid from the load chamber into the delivery chamber; and  the second diaphragm to displace the fluid from the load chamber into the delivery chamber; and o the valve means opens and closes the load and delivery chambers.

Optionally the valve means comprises a series of one-way valves arranged so that: • fluid in the load chamber can only proceed to the delivery chamber; and • fluid in the delivery chamber can leave that chamber via the outlet but cannot enter the load chamber.

Optionally the piston reciprocates in a piston chamber and is arranged such that: • a first conduit connects the piston chamber to the first diaphragm pump; • a second conduit connects the piston chamber to the second diaphragm pump; • the piston chamber is divided into separate compartments in fluid isolation from one another, one in fluid connection with the first conduit and the other in connection with the second conduit; and • as the piston reciprocates driving liquid moves in an opposite direction in each conduit.

Optionally the diaphragms are driven by oil moved by the piston.

Optionally the fluid comprises paint.

Optionally the fluid comprises UV paint.

Optionally the outlet is associated with a spray head.

Optionally the load and delivery chambers are each sufficient to receive and deliver about -70 cm of the fluid respectively, at a stroke of the piston.

Optionally the load and delivery chambers are each sufficient to receive and deliver about 40-60 cm of the fluid respectively, at a stroke of the piston.

Optionally the load and delivery chambers are each sufficient to receive and deliver about 50 cm of the fluid respectively, at a stroke of the piston.

Optionally the piston may be powered by a pneumatic motor, hydraulic motor or reciprocating electric motor.

Optionally the piston pump comprises an upper chamber and a lower chamber; a first conduit connects the upper chamber with the first diaphragm pump; and a second conduit connects the second chamber with the second diaphragm pump; the pumping system arranged such that the upper chamber, first conduit and first diaphragm pump have a fill of oil and are in fluid connection, and the lower chamber, second conduit and second diaphragm pump have a fill of oil and are in fluid connection.

IMAGES Some preferred embodiments of the invention will now be described by way of example and with reference to the accompanying images, of which: Figure 1 is a side isometric view of a part of a pump; Figure 2 is a schematic view of a piston unit and diaphragm module; and Figure 3 is an alternative schematic view of the piston unit and diaphragm module.

DETAILED DESCRIPTION Referring to figures 1-3, a pumping system 1 comprises a motor 2, a piston pump 3, and a diaphragm module 4. The motor 2 provides power to drive the piston pump 3. The motor 2 may be a pneumatic, hydraulic, or reciprocating electric motor, or any other suitable motor.

The piston unit 3 comprises an upper chamber 5, a lower chamber 6, a piston 7, an upper shaft seal 8 and a lower shaft seal 9.

The diaphragm module 4 comprises a first diaphragm pump, for example an upper cell 10, a second diaphragm pump, for example a lower cell 11, non-return valves 12 (lower valve 12a, middle valve 12b, upper valve 12c), a pump inlet 13, a load chamber 14, a delivery chamber , and a pump outlet 16. The upper cell 10 has a flexible first diaphragm 17 and the lower cell 11 has a flexible second diaphragm 18.

The piston pump 3 and the diaphragm module 4 are linked by a lower channel 19 and an upper channel 20.

To prepare the pump 1 for use, the piston 7 is positioned in the upper position as shown in figure 2, and a vacuum is applied to remove air and a non-compressible liquid, for example oil, synthetic lubricant or coolant, is added into the lower chamber 6 and the lower cell 11.

The piston 7 is then positioned in the lower position as shown in figure 3, and air is removed and oil added into the upper chamber 5 and the upper cell 10. Once all air is evacuated and oil is present, each chamber 5,6 respectively is sealed with the aid of the shaft seals 8,9.

When in use, the motor 2 is activated to start the pumping system 1. Figure 2 shows the piston 7 on the up stroke. As the piston 7 moves into the upper chamber 5 it causes oil to flow along the upper channel 20 in the direction indicated by the arrow 20a causing the first diaphragm 17 to flex and creating an area of high pressure in the delivery chamber 15.

At the same time as the piston 7 moves into the upper chamber 5 it causes oil to flow along the lower channel 19 in the direction indicated by the arrow 19a increasing the swept volume of area below the piston 7 and causing the second diaphragm 18 to flex and creating an area of low pressure in the load chamber 14. This area of low pressure causes liquid, for example UV paint, adhesives, resins and paints, from a tank (not shown) to be drawn along the pump inlet 13, through the lower valve 12a and into the load chamber 14.

Figure 3 shows the piston on the down stroke. As the piston 7 moves into the lower chamber 6 it causes each diaphragm 17,18 to flex in the opposite direction compared to the up stroke.

This creates an area of low pressure in the delivery chamber 15 and an area of high pressure in the load chamber 14. The area of low pressure in the delivery chamber 15 causes the paint to be drawn through the middle valve 12b and into the delivery chamber 15.

At the same time this movement is assisted by the high pressure generated in the load chamber 14 by the flexing of the second diaphragm 18 which drives paint into the delivery chamber 15.

The piston 7 then moves to the upstroke again as in figure 2, causing the first diaphragm 17 to flex into the delivery chamber 15 which causes the paint to move through the upper valve 12c into the outlet 16 while also filling the delivery chamber 15 in preparation for the next stroke. The outlet 16 leads to a dispenser (not shown), for example, a paint dispenser comprising a spray head for applying the paint. A hose (not shown) is connected to the outlet at one end and to the paint dispenser at the other. In an alternative embodiment of the invention there is no upper valve 12c.

The piston continues to stroke down and up to move paint from the tank to the inlet 13, through the load chamber 14 and delivery chamber 15, and to the outlet 16 and dispenser.

On the up stroke the delivery chamber 15 displaces about 50 cubic centimetres (cm ) of paint while on the down stroke the load chamber 14 displaces about 25 cm . Alternatively the load and delivery chambers 14,15 are each sufficient to receive and deliver about 30-70 cm of paint respectively.

The valves 12a-c are non-return check valves and so control the direction of flow by preventing liquid from flowing back in the direction from which it came by closing at the end of each up or down stroke.

The pump 1 is characterised in that it uses two cells 10,11 and creates alternate high and low pressure areas but uses a slow cycle of preferably less than 150 cycles per minute (cpm). The cells 10, 11 of the diaphragm module 4 work in series without either cell being exhausted of oil. The pumping action enables the diaphragm module 4 to fill on the upstroke yet pump on both strokes.

Known low pressure diaphragm pumps typically work by exhausting one diaphragm as the other diaphragm is filled, the changeover producing pressure pulse. Known high pressure diaphragm pumps typically work by using a single diaphragm that is pulsed at a relatively high speed, for example at 1,450 cpm. Both the exhausting of a cell and a faster pulsation tends to create heat/shear.

The effect of not exhausting a given cell and the slower cpm of the invention is that heat/shear is comparatively reduced compared with some known pump systems. This makes the preferred form of the invention suitable for use with certain liquids that are heat sensitive, for example for use with UV paint because oil is present in each cell 10, 11 during both the down stroke and the upstroke.

Also, some known pumps do not stop pumping when paint flow is stopped which may cause heat to be generated. In the preferred form of the present invention, the speed of the flow of UV paint can be controlled by the speed of the motor 2 moving the piston 7. If the motor speed is slowed then pulsation and the flow of paint is also slowed, so that the pump 1 works on demand which assists in reducing the risk of heat being generated while the pump 1 is being operated.

While some preferred embodiments of the invention have been described by way of example, it should be appreciated that modifications and improvements can occur without departing from the scope of the following claims.

Claims (12)

1. CLAIMS1. A pumping system comprising: • a fluid inlet; • a piston pump having a piston; • a first diaphragm pump having a first diaphragm and a load chamber; • a second diaphragm pump having a second diaphragm and a delivery chamber; • valve means; and • a fluid outlet arranged such that when in use: o a first stroke of the piston causes:  the first diaphragm to create a vacuum to draw a fluid into the load chamber via the inlet; and  the second diaphragm to drive the fluid from the delivery chamber via the outlet; o a return stroke of the piston causes:  the first diaphragm to drive the fluid from the load chamber into the delivery chamber; and  the second diaphragm to displace the fluid from the load chamber into the delivery chamber; and o the valve means opens and closes the load and delivery chambers.
2. 2. A pumping system according to claim 1, wherein the valve means comprises a series of one-way valves arranged so that: • fluid in the load chamber can only proceed to the delivery chamber; and • fluid in the delivery chamber can leave that chamber via the outlet but cannot enter the load chamber.
3. 3. A pumping system according to claim 1 or 2, wherein the piston reciprocates in a piston chamber and is arranged such that: • a first conduit connects the piston chamber to the first diaphragm pump; • a second conduit connects the piston chamber to the second diaphragm pump; • the piston chamber is divided into separate compartments in fluid isolation from one another, one in fluid connection with the first conduit and the other in connection with the second conduit; and • as the piston reciprocates driving liquid moves in an opposite direction in each conduit.
4. 4. A pumping system according to claim 1, 2 or 3, wherein the diaphragms are driven by oil moved by the piston.
5. 5. A pumping system according to any one of the preceding claims, wherein the fluid comprises paint.
6. 6. A pumping system according to any one of claims 1-4, wherein the fluid comprises UV paint.
7. 7. A pumping system according to any one of the preceding claims, wherein the outlet is associated with a spray head.
8. 8. A pumping system according to any one of the preceding claims, wherein the load and delivery chambers are each sufficient to receive and deliver about 30-70 cm of the fluid respectively, at a stroke of the piston.
9. 9. A pumping system according to any one of claims 1-7, wherein the load and delivery chambers are each sufficient to receive and deliver about 40-60 cm of the fluid respectively, at a stroke of the piston.
10. 10. A pumping system according to any one of claims 1-7, wherein the load and delivery chambers are each sufficient to receive and deliver about 50 cm of the fluid respectively, at a stroke of the piston.
11. 11. A pumping system according to any one of the preceding claims, wherein the piston is powered by a pneumatic motor, hydraulic motor or reciprocating electric motor.
12. 12. A pumping system according to claim 1, wherein the piston pump comprises an upper chamber and a lower chamber; a first conduit connects the upper chamber with the first diaphragm pump; and a second conduit connects the second chamber with the second diaphragm pump; the pumping system arranged such that the upper chamber, first conduit and first diaphragm pump have a fill of oil and are in fluid connection; and the lower chamber, second conduit and second diaphragm pump have a fill of oil and are in fluid connection. AJ Pietras & Co Attorney for the Applicant