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Patent Searching and Data


Title:
A PUMP
Document Type and Number:
WIPO Patent Application WO/2010/025511
Kind Code:
A1
Abstract:
A pump comprising a first pump mechanism having a first chamber; a first casing forming at least part of the first chamber; at least one first chamber inlet fluidly connected to the first chamber; at least one first chamber outlet fluidly connected to the first chamber; a plunger having a plunger head and a plunger shaft, the plunger head forming at least part of the first chamber; and an additional pump mechanism having an additional chamber; an additional casing forming at least part of the additional chamber, the additional casing being moveable with respect to the first casing; at least one additional chamber inlet fluidly connected to the additional chamber; at least one additional chamber outlet fluidly connected to the additional chamber; wherein the plunger shaft is connected to the additional casing.

Inventors:
WISE-JARVIS CHE LEE (AU)
Application Number:
PCT/AU2009/001152
Publication Date:
March 11, 2010
Filing Date:
September 03, 2009
Export Citation:
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Assignee:
WJR HOLDINGS PTY LTD (AU)
WISE-JARVIS CHE LEE (AU)
International Classes:
F04B1/12; F04B3/00; F04B5/02; F04B19/02; F04B33/00; F04B53/16
Foreign References:
US6702556B22004-03-09
US6027319A2000-02-22
EP0741232B11998-10-07
GB586459A1947-03-19
US6648615B22003-11-18
US4842489A1989-06-27
Attorney, Agent or Firm:
FISHER ADAMS KELLY (12 Creek StreetBrisbane, Queensland 4000, AU)
Download PDF:
Claims:
CLAIMS:

1. A pump comprising; a first pump mechanism having a first chamber a first casing forming at least part of the first chamber; at least one first chamber inlet fluidly connected to the first chamber; at least one first chamber outlet fluidly connected to the first chamber; a plunger having a plunger head and a plunger shaft, the plunger head forming at least part of the first chamber; and an additional pump mechanism having an additional chamber; an additional casing forming at least part of the additional chamber, the additional casing being moveable with respect to the first casing; at least one additional chamber inlet fluidly connected to the additional chamber; at least one additional chamber outlet fluidly connected to the additional chamber; wherein the plunger shaft is connected to the additional casing.

2. The pump of claim 1 wherein the first pump mechanism include: a second chamber, the first casing and the plunger head forms at least part of a second chamber at least one second chamber inlet fluidly connected to the second chamber; and at least one second chamber outlet fluidly connected to the second chamber.

3. The pump of claim 1 wherein the first chamber and the additional chamber are selectively fluidly connected.

4. The pump of claim 3 wherein the first chamber and the additional chamber are selectively fluidly connected by a valve.

5. The pump of claim 4 wherein the valve is located within an internal lid located between the first chamber and the additional chamber.

6. The pump of claim 2 wherein the first chamber and the second chamber are selectively fluidly connected.

7. The pump of claim 6 wherein the first chamber and the second chamber are selectively fluidly connected by a valve.

8. The pump of claim 7 wherein the valve is located within the plunger head.

9. The pump of any one of the preceding claims wherein the at least one first chamber inlet is located in the plunger head.

10. The pump of any one of claims 1 to 9 wherein the at least one first chamber inlet is located in an internal lid located between the first chamber and the additional chamber.

11. The pump of any one of claims 1 to 9 wherein the at least one additional chamber inlet is located on the plunger shaft.

12. The pump of any one of claims 1 to 9 wherein the at least one additional chamber inlet is located in an internal lid located between the first chamber and the additional chamber.

13. The pump of any one of claims 1 to 9 wherein the at least one second chamber inlet is located on the plunger shaft.

14. The pump of any one of claims 1 to 9 wherein the at least one additional chamber inlet is adjacent an end of the first casing.

Description:
"A PUMP" FIELD OF THE INVENTION

This invention relates to a pump. In particular, although not exclusively, the invention relates to a manual pump for inflating articles such as airbeds, tyres and kites. However, it should be appreciated that the pump may be modified for machine use.

BACKGROUND TO THE INVENTION

Pumps are in common usage to pump gases, liquids or slurries in many situations. They are used to inflate tyres (e.g. bicycle tyres, baby carriage tyres), camping equipment, sporting equipment (e.g. kite surfing equipment) and the like. They are also used for pumping liquids from a liquid storage facility or water from a well. Many industrial situations also require the movement of slurries, which requires the use of a pump.

Reciprocating-type pumps use a piston and cylinder arrangement with inlet valves and outlet valves integrated into the pump. Simple reciprocating-type pumps are "single acting", wherein moving the piston in one direction draws material into the pump through the inlet valve and moving the piston in the opposite direction discharges the material through the outlet valve. Alternatively, "double acting" reciprocating-type operated pumps are known, wherein drawing the material in through the inlet valve and discharging it through the outlet valve occurs when the piston is moved in both directions.

In any pumping situation, a high level of efficiency is desired. That is, for the amount of work put in, it is desirable to have a large amount of the material pumped from the pump. This reduces the number of strokes required to move the desired amount of material. However, it is also important that a reduction in the number of strokes required does not correspondingly cause a large increase in the force required to perform each stroke.

Piston pumps are often arranged such that the shaft is exposed during a part of the operation. This exposure to the environment, which is frequently dirty, sandy or wet, can result in fouling to the shaft, the inside of the cylinder and the seals. This can reduce the efficiency of the pump as it becomes harder to operate and wears out the seals.

OBJECT OF THE INVENTION

It is an object of the invention to overcome or at least alleviate one or more of the above problems and/or provide the consumer with a useful or commercial choice.

DISCLOSURE OF THE INVENTION

In one form, although it need not be the only or indeed the broadest form, the invention resides in a pump comprising: a first pump mechanism having a first chamber; a first casing forming at least part of the first chamber; at least one first chamber inlet fluidly connected to the first chamber; at least one first chamber outlet fluidly connected to the first chamber; a plunger having a plunger head and a plunger shaft, the plunger head forming at least part of the first chamber; and an additional pump mechanism having an additional chamber; an additional casing forming at least part of the additional chamber, the additional casing being moveable with respect to the first casing; at least one additional chamber inlet fluidly connected to the additional chamber; at least one additional chamber outlet fluidly connected to the additional chamber; wherein the plunger shaft is connected to the additional casing. Normally the first pump mechanism includes: a second chamber, the first casing and the plunger head forms at least part of a second chamber at least one second chamber inlet fluidly connected to the second chamber; and at least one second chamber outlet fluidly connected to the second chamber.

The first chamber and the additional chamber may be selectively fluidly connected. Preferably, the first chamber and the additional chamber are selectively fluidly connected by a valve. The valve may be located within an internal lid located between the first chamber and the additional chamber.

Alternatively, the first chamber and the second chamber may be selectively fluidly connected. Preferably, the first chamber and the second chamber are selectively fluidly connected by a valve. The valve may be located within the plunger head.

Preferably, the at least one first chamber inlet is located in the plunger head. Alternatively, the at least one first chamber inlet may be located in an internal lid located between the first chamber and the additional chamber.

Preferably, the at least one additional chamber inlet is located on the plunger shaft. Alternatively, the at least one additional chamber inlet is located in an internal lid located between the first chamber and the additional chamber.

Preferably, the at least one second chamber inlet is located on the plunger shaft. Alternatively, the at least one additional chamber inlet may be adjacent an end of the first casing.

Further features of the present invention will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

To assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect, preferred embodiments of the invention will be described by way of example only with reference to the accompanying drawings, wherein:

FIG. 1A shows a cross sectional view of a first embodiment of a pump;

FIG. 1 B shows a cut-away view of the pump shown in FIG. 1A;

FIGS. 2A to 2D show several views of the internal lid of the embodiment of the pump shown in FIG. 1 ;

FIG. 3 shows a cross sectional view of the pump of FIG. 1A showing the air flow during a downwards stroke of the pump;

FIG. 4 shows a cross sectional view of the pump of the pump of FIG. 1 A showing the air flow during an upwards stroke of the pump;

FIG. 5 shows a cross sectional view of the pump of FIG. 1A with an alternate internal lid;

FIGS. 6A to 6F shows several views of the internal lid shown in FIG. 5;

FIG. 7 shows a cross sectional view of the pump of FIG. 1A with a further alternate internal lid;

FIG. 8 shows an expanded perspective view of the internal lid of FIG. 7 in a closed position;

FIG. 9 shows an expanded perspective view of the internal lid of FIG. 7 in an open position;

FIG. 10 shows an sectional view of alternative plunger head in a closed position for use with the pump shown in FIG. 1 A;

FIG. 11 shows an further sectional view of alternative plunger head in an open position for use with the pump shown in FIG. 1A;

FIG. 12 shows an perspective view of alternative plunger head in an open position for use with the pump shown in FIG. 1A;

FIG. 13 shows a sectional view of a pump according to a second embodiment of a pump;

FIG. 14 shows the air flow during a downwards stroke of the plunger of FIG. 10;

FIG. 15 shows the air flow during an upwards stroke of the plunger of FIG. 10;

FIG. 16 shows a perspective view of an additional pump outlet valve of the pump shown in FIG. 10;

FIG. 17 shows a further perspective view of an additional pump outlet valve of the pump shown in FIG. 10;

FIG. 18 shows a sectional view of an additional pump outlet valve of the pump shown in FIG. 10; FIG. 19 shows a close up view of the internal lid in an open position;

FIG. 20 shows the internal lid engaging with the plunger head;

FIG. 21 shows a close up view of the internal lid in a closed position;

FIG. 22 shows the air flow through the internal lid when the lid is in a closed position on a downward stroke; and

FIG. 23 shows the air flow through the internal lid when the lid is in a closed position on an upward stroke.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1A and FIG. 1 B shows a cross sectional view of a manual pump for inflating articles. The pump 100 includes a first pump mechanism 200, a additional pump mechanism 300, a pump head 400 and a pump foot plate 500.

The first pump mechanism 200 includes a first casing 210, a plunger 220, a first chamber 230, a second chamber 240 and an internal lid 250. The first casing 210 is in the form of a cylinder, although other shapes may be contemplated. The first casing 210 may be manufactured from any material which is sufficiently rigid to maintain its shape during the pressures generated during operation of the pump 100. For example, polymers or metals such as stainless steel.

The plunger 220 has a plunger head 221 and a plunger shaft 223. The plunger head 221 is generally perpendicular to the plunger shaft 223. The shape of the plunger head 221 is the same as the cross sectional shape of the first casing 210, i.e. circular.

The plunger head 220 and the first casing 210 are connected by two seals 222A, 222B to form an airtight join. One of the seals 222A is adapted to create an airtight join whilst the plunger head 220 is moving in one direction and the other seal 222B is adapted to create an airtight join whilst the plunger head 220 is moving in the other direction. The seals 222A, 222B may take the form of o-rings or the like, as are well known in the field.

The plunger shaft 223 includes two internal pipes integrally formed within the shaft. One internal pipe is an inlet internal pipe 224 and the other is an outlet internal pipe 225.

The internal lid 250 is fixed to the first casing 210 and forms an airtight seal 251 with the first casing 210. The internal lid 250 also forms an airtight seal 252 with the plunger shaft 223, the seal 252 being such that it does not impede movement of the plunger shaft 223.

The first chamber 230 is defined by the internal lid 250, the plunger head 221 together with the first casing 210. The first chamber 230 is provided with a first chamber inlet valve 231 and a first chamber outlet valve 232. The first chamber inlet valve 231 and first chamber outlet valve 232 are one way valves, as are well known in the field. The first chamber inlet valve 231 allows air to flow into the first chamber 230. The first chamber outlet valve 232 allows air to flow out of the first chamber 230. The first chamber inlet valve 231 and first chamber outlet valve 232 are located on the plunger head 221 and are in fluid connection with the inlet internal pipe 224 and the outlet internal pipe 225 respectively.

The second chamber 240 is defined by the plunger head 221 together with the first casing 210. The second chamber 240 is similarly provided with a second chamber inlet valve 241 and a second chamber outlet valve 242. The second chamber inlet valve 241 and second chamber outlet valve 242 are one way valves, as are well known in the field. The second chamber inlet valve 241 allows air to flow into the second chamber 240. The second chamber outlet valve 242 allows air to flow out of the second chamber 240. The second chamber inlet valve 241 and second chamber outlet valve 242 are located on the plunger head 221 , opposite the first chamber inlet valve 231 and first chamber outlet valve 232. The second chamber inlet valve 241 and second chamber outlet valve 242 are in fluid connection with the inlet internal pipe 224 and the outlet internal pipe 225 respectively

The additional pump mechanism 300 of the pump 100 includes an additional casing 310, and an additional chamber 320. The additional casing 310 surrounds a portion of the plunger shaft 223. The additional casing 310 is fixed to the plunger shaft 223 and moves concurrently with the plunger 220. The additional casing 310 overlaps the first casing 210 and is moveable with respect to the first casing 210. A dust seal 311 is provided between the additional casing and the first casing to prevent foreign matter entering the pump 100.

The additional casing 310 is in the form of a cylinder. The additional casing 310 may be manufactured from any material which is sufficiently rigid to maintain its shape during the pressures generated during operation of the pump 100. For example, polymers or metals such as stainless steel.

The additional casing 310, together with a portion of the first casing 210 and the internal lid 250 forms an additional chamber 320. An airtight seal 312 is provided between the internal lid 250 and the additional casing 310.

An additional chamber inlet valve 321 and an additional chamber outlet valve 322 are provided. The additional chamber inlet valve 321 and an additional chamber outlet valve 322 are located on the plunger shaft 223 in fluid connection with the inlet internal pipe 224 and the outlet internal pipe 225 respectively of the plunger shaft 223. The additional chamber inlet valve 321 and the additional chamber outlet valve 322 take the form of one-way valves, as are well known in the field. The additional chamber inlet valve 321 allows air to flow into the additional chamber 320. The additional chamber outlet valve 322 allows air to flow out of the additional chamber 320.

The pump head 400 includes a handle 410, a pump inlet 420 and a pump outlet 430.

The handle 410 is formed to allow a person to grip and manually operate the pump. Gripping formations 411 , such as ridges or roughened areas may be formed integrally with the handle 410 or may be additional. The handle 410 may be adapted to be driven by a motorized drive unit (not shown).

The pump inlet 420 is in fluid connection with the inlet internal pipe 224 of the plunger shaft 223, the first chamber inlet valve 231 , the second chamber inlet valve 241 and the additional chamber inlet valve 321. The pump inlet 420 is in this instance formed integrally with the handle 410, but may be formed separately. The pump inlet 420 includes a filter 421 to remove impurities from material entering the pump 100 and prevent fouling of the pump 100. The pump outlet 430 is in fluid connection with the outlet internal pipe 225 of the plunger shaft 223, the first chamber outlet valve 232, the second chamber outlet valve 242 and the additional chamber outlet valve 322. The pump outlet 430 is in this instance formed integrally with the handle 410, but may be formed separately. The pump outlet 430 may be fitted with connecting fittings 431 , as are well known in the field. A pressure gauge 440 is incorporated into the handle 410 in fluid connection with the pump outlet 430, to display the pressure of the air being pumped.

A pump foot plate 500 is provided, to assist the operator when the pump 100 is operated by hand. By placing the operator's feet on the pump foot plate 500, movement of the plunger 220 up and down is braced. Alternatively, the pump foot plate 500 may be fixed to a surface.

FIG. 2A to 2D show several views of the internal lid 250 of the embodiment of the invention shown in FIG. 1 and FIG. 1A. FIG. 2A to 2D particularly shows the seal 251 provided between the internal lid 250 and the first casing 310, the seal 312 between the internal lid and the additional casing and the seal 252 between the internal lid and the plunger shaft 223.

FIG. 3 shows a cross sectional view of the pump 100 showing the flow of air during a downwards stroke of the plunger 220. As the pump handle 410 is pushed downwards, the plunger 220 and the additional casing 310 move downwards with respect to the first casing 210. This causes the volume of air within the additional chamber 320, the first chamber 230 and the second chamber 240 to change as described herein below.

The volume of air within the additional chamber 320 is decreased, and thus the pressure created by the decreasing volume forces the air in the additional chamber 320 to move through the additional chamber outlet valve 322, through the outlet internal pipe 225 and out of the pump outlet 430.

The volume of air within the first chamber 230 is increased, and thus the decreasing pressure within the first chamber 230 draws air in through the pump inlet 420, the inlet internal pipe 224 and the first chamber inlet valve 231 to fill the first chamber 230. The volume of air within the second chamber 240 is decreased, and thus the pressure created by the decreasing volume forces the air in the second chamber 240 move through the second chamber outlet valve 242, through the outlet internal pipe 225 to the pump outlet 430.

FIG. 4 shows a cross sectional view of the pump 100 showing the flow of air during an upwards stroke of the plunger 220. As the plunger handle 410 is pulled upwards, the plunger 220 and the additional casing 310 move upwards with respect to the first casing 210. This causes the volume of air within the additional chamber 320, the first chamber 230 and the second chamber 240 to change as described herein below.

The volume of air within the additional chamber 320 is increased and thus the decreasing pressure within the additional chamber 320 draws air in through the pump inlet 420, the inlet internal pipe 224 and the additional chamber inlet valve 321 to fill the additional chamber 320.

The volume of air within the first chamber 230 is decreased, and thus the increasing pressure forces the air to move through the first chamber outlet valve 232 and through the outlet internal pipe 225 to the pump outlet 430.

The volume of air within the second chamber 240 is increased and thus the decreasing pressure within the second chamber 240 draws air in through the pump inlet 420, the inlet internal pipe 224 and the second chamber inlet valve 241 to fill the second chamber.

FIG. 5 shows another variation of the internal lid 250. In this embodiment, the internal lid 250 also includes two relief valves 253 in fluid connection between the additional chamber 320 and the first chamber 230. The relief valves 253 are one way valves which allow air to flow from the additional chamber 320 to the first chamber 230 during compression of the additional chamber 320. The relief valves 253 utilize coil springs 254 and thus may be set to operate once a pre-determined pressure is achieved in the additional chamber 320. When the pre-determined pressure is obtained, the relief valves 253 are opened to reduce the pressure in the additional chamber 320 by allowing air to flow into the first chamber 230 which is expanding. This reduces the force required to push the plunger 220 on a downwards stroke.

FIG. 6A to 6F shows several views of the internal lid 250 in the embodiment of the invention shown in FIG. 5. The coil springs 254 of the relief valves 253 are shown more clearly. It should be appreciated that other forms of relief valves 253 may be provided, as are known in the field.

An adaptation of the internal lid shown in FIG. 5 and 6A to 6F is shown in FIG. 7. The internal lid 250 has been replaced with a two part internal lid 900 as is shown in FIG. 8.

The internal lid 900 includes an upper internal lid 910 and a lower internal lid 920. The upper internal lid 910 is provided with upper internal lid holes 911 which extend through the upper internal lid 910. An external thread 912 is provided on the upper internal lid.

The lower internal lid 920 has a closure face 921 facing the upper internal lid 910. An o-ring 922 extends around the periphery of the closure surface. An internal thread 923 is provided on the lower internal lid 920. The internal thread 923 interlocks with the external thread 912 to allow the lower internal lid 920 to move closer to and away from the upper internal lid 910 upon rotation of the lower internal lid. Lower internal lid engagement projections 924 are located at the bottom of the lower internal lid 920 and extend downwardly.

A locking member 930 is located around and connected to the plunger shaft 223. Locking member engagement projections 931 are located at the top of the locking member 930 and extend upwardly.

In use, the locking member engagement projections 931 and lower internal lid engagement projections 924 engage when the pump handle 410 is pulled upwardly to a fully retracted position. Rotation of the handle causes associated movement of the plunger shaft 223 which rotates the locking member 930 which ultimately causes rotation of the lower internal lid 910 with respect to the upper internal lid 920.

When the closure face 921 contacts the upper internal lid 920, air is unable to pass through the upper internal lid 910 as shown in FIG. 8. Hence the pump operates in the same manner as described with respect to the pump shown in FIG. 1A. That is, a high volume of air can be displaced from the pump as the first chambers 230, second chamber 240 and additional chamber 320 are all in use.

However, when the closure face 921 is not in contact with the upper internal lid 920, air is able to pass through the upper internal lid 910 as is shown in FIG. 9. The upper internal lid holes 911 fluidly connect the first chamber 230 and the additional chamber 320. Hence, no compression of air is able to occur within the first chamber 230 and the additional chamber 320 when the plunger head 221 is reciprocated. The only compression of air occurs in the second chamber 240. That is, a lower volume of air is displaced from the pump. However, the air can be displaced at a higher pressure as the same force is only compressing air in the second chamber 240.

FIG. 10 shows an alternative plunger head 221 for use with the pump shown in FIG. 1 A. The plunger head has a pressure relief valve 270 located within the plunger head 221. The pressure relief valve 270 is made up of a spring 271 , a relief body 272, a relief body magnet 273 and an o- ring 274. The relief body 272 is cylindrical and has a recess 275 that extends around the relief body 272. The relief body 272 is located within a blind relief valve hole 280 located within the plunger head 221. The spring 271 is connected to the relief body 272 and extends to an end of the relief valve hole 280. The o-ring 274 extends around the relief body 272 and is located within a relief valve channel 282 located in the plunger head 221. The relief body magnet 272 is located adjacent the end of the relief body 272. A relief valve hole magnet 283 is located within the relief valve hole.

FIG. 10 shows the relief valve 270 in a resting position. That is, air is unable to pass between the first chamber 230 and the second chamber 240. When sufficient air pressure occurs within the outlet internal pipe 225, the air pressure causes the relief body 272 to move inwardly against the spring 271 until the recess 275 extending around the relief body 272 is in alignment with a passage 284 that extends through the plunger head 221 between the first chamber 230 and the second chamber 240 as shown in FIGS. 11 and 12. Air is therefore able to pass between the first chamber 230 and the second chamber 240. When the recess 275 extending around the relief body 272 is in alignment with the passage 284 that extends through the plunger head 221 between the first chamber 230 and the second chamber 240, the relief body magnet 273 and the relief valve hole magnet 283 are attracted toward each other. Accordingly, if the air pressure with the outlet internal pipe 225 is varied slightly, there will be little or no movement of the relief body 272 toward the resting position. Once there is a substantial drop in air pressure in the outlet internal pipe 225, the spring 271 will overcome the attraction of the relief body magnet 272 and the relief valve hole magnet 283 and the relief body 272 will move back to the resting position.

FIG. 13 shows a second embodiment of a pump 101. The pump is similar in nature to the pump shown in FIG. 1A and accordingly like numerals have been used to describe like components. The pump 101 again includes a first pump mechanism 200, a additional pump mechanism 300 and a pump head 400.

The first pump mechanism 200 includes a first casing 210, a plunger 600, a first chamber 230, a second chamber 240 and an internal lid 800. The first casing 210 is in the form of a cylinder, although other shapes may be contemplated.

The plunger 600, shown in detail in FIG. 14, is formed from a plunger head 610 and a plunger shaft 620. The plunger shaft 620 is hollow, thus forming an outlet pipe 621 in fluid communication with the pump outlet (not shown) of a pump.

The plunger head 610 is formed from an upper plunger head 611 and a lower plunger head 612. The lower plunger head 612 contains a lower one-way valve 613 which only allows air to travel out of the second chamber 240. The lower one-way valve 613 is preferably in the form of a flap valve located in fluid communication with the outlet pipe 621 within the plunger shaft 620. An internal seal 614 is present between the upper plunger head 611 and the lower plunger head 612 to prevent leakage through the join between the upper plunger head 611 and the lower plunger head 612.

The upper plunger head 611 contains an upper one-way valve 615, which only allows fluid to travel out of the first chamber 230. Preferably the upper one-way valve 615 is in the form of an o-ring seated in a groove 616 of the upper plunger head 611. The upper one-way valve 615 is in fluid communication with the outlet pipe 621 within the plunger shaft 620. An upper plunger head seal 617 is fitted between the upper plunger head 611 and the first casing 210.

An outer casing 700 is provided which surrounds at least a portion of, and is co-axial with, the first casing 210. An outer casing air gap 710. is formed between the outer casing 700 and a portion of the first casing 210. The outer casing air gap 710 is in fluid communication with the atmosphere at the top of the outer casing 700 via a second chamber inlet 720.

The second chamber inlet 720 is provided between the outer casing air gap 710 and the second chamber 210. A second chamber inlet valve 730 regulates the air flow through the second chamber inlet 720. The second chamber inlet valve 730 is preferably in the form of a one-way valve, such as a flap valve.

The additional pump mechanism 300 of the pump 100 includes an additional casing 310, and an additional chamber 320. The additional casing 310 surrounds a portion of the plunger shaft 620. The additional casing 310 is fixed to the plunger shaft 620 and moves concurrently with the plunger 600. The additional casing 310 overlaps the first casing 210 and is moveable with respect to the first casing 210. An additional pump outlet valve 340 is located adjacent the pump head 400.

The lower end of the additional casing 310 includes a casing seal 740. When the plunger 600 is fully depressed, the additional casing 310 and casing seal 740 fit into the outer casing air gap 710 between the outer casing 700 and the first casing 210. This serves to seal the pump 101 from the environment and prevent ingress of dirt, water or other contaminants.

In use, as the plunger 600 is depressed, the air within the second chamber 240 is compressed and thus forced out through the lower oneway valve 613 to the outlet pipe 621 within the plunger shaft 620, as shown in FIG. 14. The downwards pressure on the plunger head 610 compresses the groove 616 of the upper plunger head 611 and thus creates a seal between the groove 616 of the upper plunger head 611 and the o-ring of the upper one-way valve 615. Thus air is prevented from exiting the first chamber 230 through the upper one-way valve 615.

Compression of the air with the second chamber 240 places pressure on the second chamber inlet valve 730, and thus prevents air from exiting the second chamber 240 through the second chamber inlet valve 730. Air from the second chamber 240 is only allowed to exit through the lower one-way valve 613 in the lower plunger head 612.

When the plunger 600 is extended, as shown in FIG. 15, air within the first chamber 230 is compressed and exits the first chamber 230 through the upper one-way valve 615 to the outlet pipe 621 within the plunger shaft 620.

During the extension of the plunger 600, air from the first chamber 230 is compressed and thus pressure is placed on the lower one-way valve 613 from the first chamber 230. This creates a seal between the lower one-way valve 613 and the lower plunger head 612 and prevents air from exiting the first chamber 230 through the lower one-way valve 613 into the second chamber 240.

As the second chamber 240 is expanded by the extension of the plunger 600, air is drawn from the atmosphere, through the outer casing air gap 710 between the outer casing 700 and the first casing 210 and in through the second chamber inlet 720 and second chamber inlet valve 730.

This arrangement of one-way valves has the advantage of the plunger head 610 only requiring one seal between the plunger head 610 and the first casing 210. This reduces the friction required to move the plunger 600 up and down within the first casing 210. Further, reducing the size of the plunger head enables a larger volume of air to be compressed by the plunger head 610.

FIGS. 16 and 17 show further detail of the additional pump outlet 340. The additional pump outlet 340 includes an additional pump cap ' 341 which has a series of outlet holes 342 that extend through the additional pump cap 342. An outlet hole o-ring 343 extends around the additional pump cap 341 over the outlet holes 342. A plunger access hole 621 is located through the plunger shaft above the additional pump cap 342.

In use, when air within the additional chamber 320 is compressed, air passes through the outlet holes 343 as shown in FIG. 18. Once the air passes out of the outlet holes 343, the air then passes through the plunger access hole 621 into the plunger and then out of the pump head 400. When air is not being compressed, the o-ring 343 prevents any air from passing back through outlet holes 343 from the plunger shaft 620.

FIG. 19 shows further detail of the internal lid 800 is located at the top of the first casing 210 and separating the first chamber 230 and the additional chamber 240. The internal lid 800 is formed from an upper internal lid 810 and a lower internal lid 820. The upper internal lid 810 has an upper internal lid seal 812 which seals the upper internal lid 810 with the additional casing 310. The upper internal lid 810 is provided with upper internal lid holes 811 passing through the upper internal lid 810.

The lower internal lid 820 is provided with lower internal lid holes 821 passing through the lower internal lid 820. The lower internal lid 820 is moveable with respect to the upper internal lid 810 via interlocking threads located on both the upper internal lid 810 and the lower internal lid 820.

An internal lid seal 830 is located between the upper internal lid 810 and the lower internal lid 820, which serves to seal the upper internal lid holes 811 and the lower internal lid holes 821 and prevent fluid communication between the additional chamber 320 and the first chamber 230 when the lower internal lid 820 abuts against the upper inlet lid.

The lower internal lid 820 is provided engagement projections 822 which fit into corresponding recessed 823 in the plunger head 610 as shown in FIG. 17. It should be appreciated that the lower internal lid 820 may be provided with recesses which receive corresponding projections on the plunger head 610.

In use, when the plunger 600 is fully extended, the projection 822 of the lower internal lid 820 becomes located into the recess 823 of the plunger head 610 as shown in FIG. 20. When the projection 822 of the lower internal lid 820 is engaged in the recess 823 in the plunger head 610, rotation of the plunger head 610 forces the lower internal lid 820 to rotate and therefore screw into or out of the upper internal lid 810. The internal lid seal 830 then creates a seal between the lower internal lid 820 and upper internal lid 810. This prevents air flowing from the additional chamber 320 into the first chamber 230 when the lower internal lid 820 engages with the upper internal lid 810 as shown in FIG. 18.

FIG. 21 shows an additional casing air gap 755 provided between the additional casing 310 and the first casing 210. The additional casing air gap 755 is in fluid connection with an upper internal lid channel 760 which leads to a plunger shaft air gap 761 located adjacent to the plunger shaft 620.

The upper internal lid 820 is provided with an upper internal lid valve seat 813 containing a lower internal lid floating valve 814 which forms an additional chamber inlet valve 815. The upper internal lid valve seat 813 is in fluid connection with the upper internal lid channel 760 via the plunger shaft air gap 761.

The lower internal lid 820 is provided with a lower internal lid valve seat 823 containing a lower internal lid floating valve 824 which forms a first chamber inlet valve 825. The lower internal lid valve seat 823 is in fluid connection with the upper internal lid channel 760 via the plunger shaft air gap 761.

In use, when the lower internal lid 820 is closed, and the plunger 600 is depressed, air flows into the additional casing air gap 755 and into the upper internal lid channel 760 as shown in FIG. 22. The upper internal lid floating valve 814 presses into the upper internal lid valve seat 813 by the movement of the plunger 600. Further, air from the additional chamber 320 is compressing the upper internal lid floating valve 814 onto the upper internal lid valve seat 813. A vacuum is formed within the first chamber 230 which also assists in forcing the upper internal lid floating valve 814 onto the upper internal lid valve seat 813. Thus air is prevented from entering the additional chamber 320.

The lower internal lid floating valve 824 is released from the lower internal lid valve seat 823 by the upward movement of the plunger 600. Further, air from the first chamber 230 is compressing the lower internal lid floating valve 824 onto the lower internal lid valve seat 823. A vacuum is formed within the additional chamber 320 which also assists in forcing the lower internal lid floating valve 824 onto the lower internal lid valve seat 823. Thus air is allowed to enter the first chamber 230.

When the plunger 600 is being extended, as shown in FIG. 23, air flows into the additional casing air gap 755 and into the upper internal lid channel 760. The upper internal lid floating valve 814 is released from the upper internal lid valve seat 813 by the movement of the plunger 600 and thus air is allowed to enter the additional chamber 320.

The lower internal lid floating valve 824 is pressed into the lower internal lid valve seat 823 by the movement of the plunger 600 and thus air is prevented from entering the first chamber 230.

When the lower internal lid 820 is closed against the upper internal lid 810, the pump operates as a three chamber pump creating a high volume air output at relatively low pressure. When the lower internal lid 820 is open, the pump operates as a single chamber pump, as the volume of the additional chamber 320 together with the first chamber 230 is substantially constant. Thus the work required to operate the pump is reduced which allows an operator to produce a higher pressure output.

For example, when pumping up a bicycle tire, the pump is initially set with the lower internal lid closed. This allows a large volume of air to be pumped at low pressure. Once the bicycle tire is nearly pumped up to capacity, the lower internal lid is opened. This allows air to be pumped at high pressure into the already pressurized tire to fill the tire.

In a particularly preferred embodiment, the diameter of the first casing 210, and thus the first chamber 230 and the second chamber 240, is smaller than the diameter of the additional casing 310, and thus the additional chamber 320. The relatively small area of the plunger head reduces the force required to pump the volume of the second chamber 240.

Thus, it can be seen that in the pump 100 and 101 of the current invention, when compared to a standard double-acting piston pump of similar size, a greater output of material is achieved on the downwards stroke. The number of strokes required to move a volume of material may thus be reduced.

Additionally, the provision of the additional casing 740 and seal 710 protects the internals of the pump 101 from the environment and prevents fouling and the seals from dirt, sand, liquids etc.

Throughout the specification, the aim has been to describe the invention without limiting the invention to any one embodiment or specific collection of features. Persons skilled in the relevant art may realize variations from the specific embodiments that will nonetheless fall within the scope of the invention. For example, the size of the pump may vary to accommodate the application. Applications such as bicycle tyre pumps would be of a small size, whereas water pumps would suitably be of a larger size. Similarly, various materials may be used to manufacture the pump 100. For example, plastics, aluminum or stainless steel, as is well known in the field.

It will be appreciated that various other changes and modifications may be made to the embodiment described without departing from the spirit and scope of the invention.