PUMP

[001] This invention relates to a pump, and more specifically, but not exclusively, to a grout pump.

[002] In mining and tunnelling it is common practice to improve the stability of the rock surrounding the excavation by fixing bolts into holes drilled into the rock. One method of fixing such bolts is with grout which is pumped into the holes. The grout most commonly has a cementitious base, but grout with a resin base may also be used. The grout may be pumped into the hole prior to insertion of the bolt, or may be pumped into the hole after insertion of the bolt, to fill the annular space. Typically, the volume of grout pumped into each hole is in the range of 2 to 6 litres. The grouts have high viscosity and must be pumped up to 6 metres through hoses with internal diameters of 12 - 20 mm. High pumping forces are thus needed. Examples of the grouts are "Capcem" Pumpable Grout and "Capcem" PLG grout.

[003] In large mining operations activities are carried out concurrently at many working places (as many as several hundred on a single mine) . In this type of mining, the working places are small and widely scattered, and travel between the working places is difficult. The number of rock bolts installed and grouted at each working place each shift is usually small, in the range of 2 to 8. This creates a requirement for the grout pumps to be small, light to carry, easy to set up, clean and disassemble, simple to operate, resistant to damage and highly reliable. Because of the high pumping pressures needed, the pumps are powered. Power sources used are compressed air or high-pressure water.

[004] A commonly used type of pump which at least partially satisfies the requirements is a single-chamber single-acting reciprocating piston

or diaphragm pump. A widely-used example of this type of pump is the "Sindele" pump, which is described in South African patent no. 96/3402.

[005] Pumps of this type require that the piston or diaphragm be returned to its original position after completion of the discharge stoke. A disadvantage of the prior art pumps is that the return is done by hand. This manual operation is fatiguing, and may require considerable muscular strength from the operator, which restricts use of the pump.

[006] A means of ameliorating these problems has been sought.

[007] According to the invention there is provided a pump comprising: a housing; a separator within the housing dividing the housing into a material chamber and a driving fluid chamber, the separator being movable between a loading position and a discharge position; a discharge port from the material chamber; a material loading port for the material chamber; an inlet port to the driving fluid chamber; a venturi means; and a valve means for directing driving fluid into the driving fluid chamber through the inlet port to force the separator from its loading position to its discharge position thereby to discharge material through the delivery port from the material chamber, and for directing driving fluid through the venturi means to extract fluid from the driving fluid chamber to create a low pressure within the driving fluid chamber thereby to force the separator back to its loading position from its discharge position.

[008] According to the invention there is provided a pump comprising:

a housing; a separator within the housing dividing the housing into a material chamber and a driving fluid chamber, the separator being movable between a loading position and a discharge position; a discharge port from the material chamber; a material loading port for the material chamber; an inlet port to the driving fluid chamber; an extractor means; and a valve means for directing driving fluid into the driving fluid chamber through the inlet port to force the separator from its loading position to its discharge position thereby to discharge material through the delivery port from the material chamber, and for directing driving fluid through the extractor means to extract fluid from the driving fluid chamber thereby to force the separator back to its loading position from its discharge position.

[009] Unlike the prior art systems which require the operator to manually return the piston or diaphragm to its original position after completion of the discharge stoke, in the present invention the return stroke is completed by the valve means of the pump thus reducing the physical effort required by the operator.

[010] It is understood by the person skilled in the art that a venturi means comprises a conduit arranged to enable an increase in the velocity of fluid flowing through part of the conduit, resulting in a decrease in the fluid pressure at that part of the conduit. Preferably, the venturi means is a venturi or an extractor means. The extractor means may be an ejector.

[Oil] The housing may include two sections secured to one another by fastening means. The sections may be hemispherical, and the fastening means may be bolts and nuts.

[012] The separator is preferably a diaphragm. The diaphragm may be made of rubber. The diaphragm is preferably clamped between the two sections of the housing. In another form of the invention the separator is a piston.

[013] The valve means may include first and second valves. The first valve is preferably in use connected to a driving fluid source, and can communicate with the second valve and the venturi means. The second valve can preferably in use communicate with the first valve, the driving fluid chamber and the venturi means. The first and second valves are thus preferably three-way valves. However, separately operated open/shut valves may also be used.

[014] The driving fluid may be compressed air or water. The material may be grout.

[015] According to the invention, there is provided a method of operating a pump having a separator within a housing dividing the housing into a driving fluid chamber and a material chamber comprising the steps of: loading material into the material chamber; introducing driving fluid into the driving fluid chamber to force the separator from a loading position to a discharge position to discharge the material from the material chamber; and extracting fluid from the driving fluid chamber to create a low pressure within the driving fluid chamber thereby to force the separator back into its loading position.

[016] Further according to the invention there is provided a method of operating a pump having a separator within a housing dividing the housing into a driving fluid chamber and a material chamber comprising the steps of: loading material into the material chamber; introducing driving fluid into the driving fluid chamber to force the separator from a loading position to a discharge position to discharge the material from the material chamber; and extracting fluid from the driving fluid chamber thereby to force the separator back into its loading position.

[017] In the preferred form of the invention fluid is extracted from the driving fluid chamber by connecting the driving fluid chamber to venturi means and discharging driving fluid through the venturi means.

[018] The invention is now illustrated with reference to (although not limited to) the following Figures of the accompanying drawings in which:

Figure 1 shows a shows a diagrammatic cross-sectional side view of a first embodiment of a pump according to the invention.

Figures 2a to 2c show diagrammatic views of the pump shown in Figure 1 its valves and venturi showing the pumping, return stroke and off positions, respectively.

Figure 3 shows a diagrammatic cross-sectional side view of a second embodiment of the pump according to the invention.

Figures 4a to 4c show diagrammatic views of the pump shown in Figure 3 its valves and venturi showing the pumping, return stroke and off positions, respectively.

[019] In figure 1, a single-chamber single-acting reciprocating grout pump 10 has a housing 12 constructed from two hemispherical sections 14.1 and 14.2 with external flanges 16 on their equatorial planes. The two sections 14.1 and 14.2 are bolted together via their flanges 16 to form the housing 12. Inside the housing 12 is a flexible rubber diaphragm 18 shaped to fit snugly against the inner surface of the lower section 14.1 when the diaphragm 18 is in its loading position, which is shown in figure 1. The diaphragm 18 divides the inside of the housing 12 into a compressed air chamber 22 and a grout chamber 24.

[020] The lower section 14.1 has a compressed air inlet port 26, with an external valve/venturi arrangement 28. The upper section 14.2 has a grout loading port 30 and a grout discharge port 32.

[021] In figures 2a to 2c, the valve arrangement 28 includes 3-way valves 34 and 36 and a venturi 38 with a throat 40. A compressed air source (not shown) is connected via a conduit 42 to the 3-way valve 34.

[022] In use, grout is loaded through the grout loading port 30, which is then closed. The valves 34 and 36 are then positioned as shown in figure 2a. Compressed air is introduced into the compressed air chamber 22, through the compressed air inlet port 26. The diaphragm 18 is forced upwards by the compressed air to discharge the grout through the grout discharge port 32. At the completion of this stroke the diaphragm 18 is inverted and tight against the inner surface of upper section 14.2. The grout loading port 30 is then opened again and the valves 34 and 36 are then switched to the positions shown in figure 2b.

The compressed air is routed through the venturi 38. This creates a low pressure in the throat 40 of the venturi 38. The compressed air chamber 22 of the pump 10 is connected to the throat 40 of the venturi 38. The low pressure in the throat 40 extracts the air from the compressed air chamber 22, creating a low pressure which sucks the diaphragm 18 back to its starting position against the lower section 14.1. The valves 34 and 36 then are positioned as shown in figure 2c, to shut off flow of compressed air.

[023] In figure 3, there is a single-chamber single-acting reciprocating grout pump 110. Like features with pump 10 are identified with like reference numerals.

[024] Grout pump 110 has a housing 12 constructed from two hemispherical sections 14.1 and 14.2 with external flanges 16 on their equatorial planes. The two sections 14.1 and 14.2 are bolted together via their flanges 16 to form the housing 12. Inside the housing 12 is a flexible rubber diaphragm 18 shaped to fit snugly against the inner surface of the lower section 14.1 when the diaphragm 18 is in its loading position, which is shown in figure 3. The diaphragm 18 divides the inside of the housing 12 into a compressed air chamber 22 and a grout chamber 24.

[025] The lower section 14.1 has a compressed air inlet port 26, with an external valve/ ejector arrangement 29. The upper section 14.2 has a grout loading port 30 and a grout discharge port 32.

[026] In figures 4a to 4c, the valve arrangement 29 includes 3-way valves 34 and 36 and an ejector 39 with an inlet 41. A compressed air source (not shown) is connected via a conduit 42 to the 3-way valve 34.

[027] In use, grout is loaded through the grout loading port 30, which is then closed. The valves 34 and 36 are then positioned as shown in figure 4a. Compressed air is introduced into the compressed air chamber 22, through the compressed air inlet port 26. The diaphragm 18 is forced upwards by the compressed air to discharge the grout through the grout discharge port 32. At the completion of this stroke the diaphragm 18 is inverted and tight against the inner surface of upper section 14.2. The grout loading port 30 is then opened again and the valves 34 and 36 are then switched to the positions shown in figure 4b. The compressed air is routed through the ejector 39. The compressed air chamber 22 of the pump 110 is connected to the inlet 41 of the ejector 39. The air is extracted from the compressed air chamber 22, creating a low pressure which sucks the diaphragm 18 back to its starting position against the lower section 14.1. The valves 34 and 36 then are positioned as shown in figure 4c, to shut off flow of compressed air.

[028] It will be appreciated that many modifications or variations of the invention are possible without departing from the spirit or scope of the invention.