The present disclosure relates to a water pressurisation system. Particularly, but not exclusively, the disclosure relates to a water pressurisation system comprising a pneumatic water pump and a pneumatic actuating valve.
BACKGROUND
Toilets are commonly provided on vehicles such as trains and coaches. Such toilets must operate using a limited quantity of water. Furthermore, the water may be provided at a relatively low pressure, as compared to mains connected toilet systems.
Traditionally diaphragm operated pneumatic pumps are used in vacuum toilet systems for cleaning of toilet pan/bowl, which requires electricity and an electronic controller to be operated, adding to their complexity and cost. Furthermore, the vacuum toilet system may not provide optimum cleaning.
There are various known ways in which to provide toilet systems for cleaning of the toilet pan. US3184761A describes a toilet system where available power from the inlet water pressure is utilized by directing the flow thereof alternatively to the sides of an oscillating piston such that the piston will reciprocate and provide a source of mechanical power. US6082979A describes a vacuum toilet assembly including a vacuum toilet and a vacuum tank. A simple air pump is used to remove air from the tank to create a partial vacuum. The pump comprises an electrically powered reciprocating diaphragm pump.
What is required is a toilet system which provides sufficient cleaning of the toilet pan without consuming large quantities of water and power, and which may operate with limited water pressure and in remote areas.
SUMMARY OF THE INVENTION
Aspects and embodiments of the invention relate to a water pressurisation system and to a method of forming a water pressurisation system.

According to an aspect of the invention, there is provided a water pressurisation system comprising: a pneumatic water pump; and a pneumatic actuating valve; wherein the pneumatic water pump defines a water chamber and a pneumatic chamber, an inlet valve adapted to be fluidly couple the water chamber to a water source, and an outlet valve adapted to fluidly couple the water chamber to a toilet pan, the pneumatic chamber having a piston pneumatically separating the pneumatic chamber into a first side and a second side, the piston having a head hydraulically separating the water chamber into a first side and a second side; and wherein the outlet valve is an air pilot operated valve, and the pneumatic water pump is actuated to a primed condition by pneumatically connecting the pneumatic chamber first side to a pneumatic source, and the pneumatic water pump is actuated to a flushed condition by pneumatically connecting the pneumatic chamber second side and the air pilot operated valve to the pneumatic source.
This water pressurisation system is purposed to use for cleaning of toilets with a high pressure water jet using pneumatic air pressure. The system can run with or without electricity. As the water pump is pneumatically driven, at high pressure, water consumption per flush can be reduced to as little as 1 Litre per flush.
The pilot operated valve at the outlet of the pump avoids any leakage in case of high inlet pressure due to high water head, as the outlet valve is only opened upon pressing of flushing valve/switch controlling the pneumatic actuating valve.
The inlet valve may be a non-return valve. The pilot operated valve at the outlet of the pump avoids any leakage in case of failure of a non-return valve.
The pneumatic actuating valve may be a spring return valve. The system therefore does not need an electrical power supply to operate, and is driven by pneumatic power only. The purposed invention does not need any electronic controller to operate. This arrangement further contributes to a low cost system due to there being no electrical controller and no potentially complex electrical maintenance. The system installation and maintenance is relatively easy, as compared to more complex systems employing individual vacuum pumps or electrical motors.
Alternatively, the pneumatic actuating valve may be a solenoid operated valve.

The pneumatic actuating valve may be a directional control valve. The pneumatic actuating valve may be a 5/2 valve. Pneumatic 5/2 valve is used as flushing valve.
The air pilot operated valve may be a 2/2 valve.
The air pilot operated valve may be a non-return valve. The air pilot pressure may be 0 to 4 bar.
The cracking pressure of the non-return inlet valve may be 0.1 bar.
The cracking pressure of the non-return outlet valve may be 0 to 2.5 bar.
According to another aspect of the invention, there is provided a method of forming a water pressurisation system, the method comprising the steps of:
providing a pneumatic water pump having a water chamber and a pneumatic chamber, the pneumatic chamber having a piston pneumatically separating the pneumatic chamber into a first side and a second side, the piston having a head hydraulically separating the water chamber into a first side and a second side; providing a pneumatic actuating valve; fluidly coupling the water chamber to a water source using an inlet valve; fluidly coupling the water chamber to a toilet pan using an outlet valve, wherein the outlet valve is an air pilot operated valve, and pneumatically connecting the pneumatic chamber first side to a pneumatic source to actuate the pneumatic water pump to a primed condition; and simultaneously pneumatically connecting the pneumatic chamber second side and the air pilot operated valve to the pneumatic source to the pneumatic water pump to a flushed condition.
Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS
One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
Figure 1 is a schematic side elevation of the water pressurisation system in accordance with a first embodiment of the present invention;
Figure 2 is a perspective view of the water pressurisation system of Figure 1 in a primed condition; and
Figure 3 is a perspective view of the water pressurisation system of Figure 1 in a flushed condition.
Figure 4 is a schematic side elevation of the water pressurisation system in accordance with a second embodiment of the present invention;
DETAILED DESCRIPTION
The water pressurisation system 10 has a pneumatic water pump 50, a pneumatic actuating valve 80 and an air pilot operated valve 40.
The pneumatic water pump 50 is a cylinder 52 having a first end wall 54 and a second end wall 56. The cylinder 52 and end walls 52, 54 define a water chamber 60 and a pneumatic chamber 70. The water chamber 60 and a pneumatic chamber 70 are separated by a central wall 58.
The water chamber 60 has an inlet 62 and an outlet 64. A non-return inlet valve 66 is positioned at the inlet 62 of the water chamber 60. A non-return outlet valve 68 is positioned at the outlet 64 of the water chamber 60. The air pilot operated valve 40 is positioned at the outlet 64 of the water chamber 60, downstream of the non-return outlet valve 68.
The pneumatic chamber 70 has an A pneumatic port 72 and a B pneumatic port 74.

Referring briefly to Figure 2, the water pump 50 has a piston 90. The piston 90 has a first end plate 92 and a second end plate 94. The end plates 92, 94 are connected by a tie rod 96. The first end plate 92 is disposed within the water chamber 60 and the second end plate 94 is disposed within the pneumatic chamber 70. The tie rod 96 passes through an aperture 59 provided in the central wall 58. The aperture 59 is centrally aligned within the cylinder 52. The first end plate 92 hydraulically separates the water chamber 60 into a first side and a second side. The second end plate 94 pneumatically separates the pneumatic chamber 70 into a first side and a second side. The first side is exposed to the A pneumatic port 72 and the second side is exposed to the B pneumatic port 74.
The pneumatic actuating valve 80 is a 5/2 valve having five ports and two spool positions. The five ports are as follows:
1. pressurised air input port 81;
2. first pneumatic output port 82;
3. first exhaust port 83 (not shown);
4. second pneumatic output 84 port; and
5. second exhaust port 85 (not shown).
The pneumatic actuating valve 80 is actuated through a mechanical push button 86.
The air pilot operated non return valve 40 is a 2/2 valve having an inlet port 44 and an outlet port 46. Pilot port C 42 is used to control flow between the inlet port 44 and outlet port 46.
Hydraulic Connections
The water pressurisation system 10 is fluidly connected to a water source, for example an overhead tank 20 by pipe 21. The water pressurisation system 10 is fluidly connected to a toilet pan 30 by pipe 22.
Pneumatic Connections
The pneumatic actuating valve 80 is fluidly connected to a source of pressurised air, for example a pneumatic pump 25, by pneumatic line 26.

The first pneumatic output port 82 is fluidly connected to the A pneumatic port 72 of pneumatic chamber 70 by pneumatic line 27. The second pneumatic output port 84 is fluidly connected to the B pneumatic port 74 of pneumatic chamber 70 and to the pilot port C 42 of air pilot operated valve 40 by pneumatic line 28. 5
Operation
The water pressurisation system 10 uses the pneumatic water pump 50 to draw water from the water source 20 and pump the drawn water to a toilet pan 30 in a double acting manner. 10
Primed Condition
Referring to Figure 2, the piston 90 is actuated in a backward stroke so as to draw water from the water source 20 as follows:
15
The first pneumatic output port 81 is fluidly connected to the A pneumatic port 72 of pneumatic chamber 70 and the B pneumatic port 74 of pneumatic chamber 70 is connected to exhaust such that air flows into the first side of the pneumatic chamber 70 and drives the second end plate 94 towards the second end wall 56. The piston 90 thereby moves to the
20 right (backward stroke), and due to the tie rod 96 connection to the first end plate 92, the first end plate 92 is pulled towards the central wall 58. Movement of the first end plate 92 within the water chamber 60 creates a vacuum effect to overcome the cracking pressure of the inlet valve 66 and draw water from the water source 20 into the first side of the water chamber 60. The pneumatic water pump 50 is thus actuated to a primed condition.
25
A non-return valve allows the fluid to flow from one side and restricts the reverse flow. Cracking pressure of a non-return valve is the minimum value of pressure upon which the flow path opens and flow starts. The cracking pressure is usually defined by the tension of spring used within the non-return valve. The non-return inlet valve 66 has a cracking
30 pressure of 0.1bar. At this pressure, which is created due to suction created in backward stroke of the piston 90, the non-return inlet valve 66 opens. Opening of the non-return inlet valve 66 allows water to enter into water chamber 60 from overhead tank 20 via inlet 62. The same non-return inlet valve 66 restricts the reverse flow of water from the water chamber 60 to the overhead tank 20. The non-return inlet valve 66 is a normally closed type valve.
35
7

Flushed Condition
Referring to Figure 3, the piston 90 is actuated in a forward stroke so as to drive water from the water chamber 60 to the toilet pan 30 as follows: 5
The second pneumatic output port 84 is fluidly connected to the B pneumatic port 74 of pneumatic chamber 70 and to the pilot port C 42 of air pilot operated non return valve 40, and the first pneumatic output port 81 is fluidly connected to exhaust such that air flows into the second side of the pneumatic chamber 70 and drives the second end plate 94 towards
10 the central wall 58. The piston 90 thereby moves to the left, and due to the tie rod 96 connection to the first end plate 92, the first end plate 92 is pushed towards the first end wall 54. Movement of the first end plate 92 within the water chamber 60 drives the water towards the outlet valve 68 and overcomes the cracking pressure of the outlet valve 68 and air pilot operated valve 40 and thereby delivers the water towards the toilet pan 20. The pneumatic
15 water pump 50 is thus actuated to a flushed condition.
The non-return outlet valve 68 has a cracking pressure of 0.8bar. This pressure is generated during the forward stroke of the piston 66. Opening of the non-return outlet valve 68 allows water to exit from water chamber 60 to the toilet pan 30. The same non-return outlet valve 20 68 restricts the reverse flow of air from pan side to water barrel during the backward stroke.
Ideally non-return outlet valve 68 does not allow the water to flow until the water pump 50 actuates and creates a minimum pressure of 0.8bar. But in some cases the non-return outlet valve 68 may fail to do so due to external factors such as vibration or contamination. In that
25 case water may begin to leak to the pan 30. However, the air pilot operated valve 40 may be used in addition to or instead of the non-return outlet valve 68 to prevent any such leakage. The air pilot operated valve 40 remains closed and restricts any water leakage and opens only when the pneumatic pressure enters into it. Pneumatic actuating valve 80 supplies pressurised air to the pneumatic chamber 70 and same pneumatic line 28 is tapped to pilot
30 port C 42 of the air pilot operated valve 40 pilot port to open the air pilot operated valve 40.
In an alternative embodiment, the non-return outlet valve 68 is a normally open type valve.
The air pilot operated valve 40 also prevents water leakage to the pan 20 in cases when the 35 inlet line pressure (pipe 21) is higher than the non-return inlet valve 66 and non-return outlet
8

valve 68 cracking pressures. The air pilot operated valve 40 restricts the water flow irrespective of water pressure up to practical limitations. Water will not flow without air signal to the air pilot operated valve 40. In practice, this makes the system workable up-to 8 bar inlet water pressure.
Referring to Figure 4, a water pressurisation system 210 is shown in accordance with a second embodiment of the present invention. The water pressurisation system 210 of Figure 4 shares many of the same features as the water pressurisation system 10 of Figure 1, and as such only the significant differences shall be described in detail. Furthermore, similar reference numerals shall be used to denote similar features, prefixed by a "2" to denote that those features are described in reference to the water pressurisation system 210 of Figure 4.
The water pressurisation system 210 has a pneumatic water pump 250, a pneumatic actuating valve 280 and an air pilot operated valve 240.
The pneumatic actuating valve 280 is a solenoid operated 5/2 valve, and is represented in Figure 4 using schematics. The pneumatic actuating valve 280 is actuated through an electrical push button 287. The electrical push button 287 is controlled and powered by power source/controller 289.
In alternate embodiments, the electrical push button 287 may be replaced by a lever, a rotary knob, a solenoid or an air pilot operated button.

WE CLAIM

Claims:A water pressurisation system comprising:
a pneumatic water pump; and
a pneumatic actuating valve;
wherein the pneumatic water pump defines a water chamber and a pneumatic chamber, an inlet valve adapted to be fluidly couple the water chamber to a water source, and an outlet valve adapted to fluidly couple the water chamber to a toilet pan,
the pneumatic chamber having a piston pneumatically separating the pneumatic chamber into a first side and a second side, the piston having a head hydraulically separating the water chamber into a first side and a second side; and wherein
the outlet valve is an air pilot operated valve, and
the pneumatic water pump is actuated to a primed condition by pneumatically connecting the pneumatic chamber first side to a pneumatic source, and the pneumatic water pump is actuated to a flushed condition by simultaneously pneumatically connecting the pneumatic chamber second side and the air pilot operated valve to the pneumatic source.

2. A water pressurisation system according to claim 1, wherein the inlet valve is a non-return valve.

3. A water pressurisation system according to claim 1, wherein the pneumatic actuating valve is a spring return valve.

4. A water pressurisation system according to claim 1, wherein the pneumatic actuating valve is a manual or solenoid operated valve.

5. A water pressurisation system according to claim 1, wherein the pneumatic actuating valve is a directional control valve.

6. A water pressurisation system according to claim 1, wherein the air pilot operated valve is a 2/2 valve.

7. A water pressurisation system according to claim 1, further comprising a non-return valve arranged at the outlet of the water chamber.

8. A water pressurisation system according to claim 2, wherein the cracking pressure of the non-return inlet valve is 0.1 bar.

9. A water pressurisation system according to claim 7, wherein the cracking pressure of the non-return outlet valve is 0 to 2.5 bar.

10. A method of forming a water pressurisation system, the method comprising the steps of:
providing a pneumatic water pump having a water chamber and a pneumatic chamber,
the pneumatic chamber having a piston pneumatically separating the pneumatic chamber into a first side and a second side, the piston having a head hydraulically separating the water chamber into a first side and a second side;
providing a pneumatic actuating valve;
fluidly coupling the first side of the water chamber to a water source using an inlet valve;
fluidly coupling the first side of the water chamber to a toilet pan using an outlet valve, wherein the outlet valve is an air pilot operated valve, and
pneumatically connecting the pneumatic chamber first side to a pneumatic source to actuate the pneumatic water pump to a primed condition; and
simultaneously pneumatically connecting the pneumatic chamber second side and the air pilot operated valve to the pneumatic source to the pneumatic water pump to a flushed condition. , Description:TECHNICAL FIELD

The present disclosure relates to a water pressurisation system. Particularly, but not exclusively, the disclosure relates to a water pressurisation system comprising a pneumatic water pump and a pneumatic actuating valve.

BACKGROUND

Toilets are commonly provided on vehicles such as trains and coaches. Such toilets must operate using a limited quantity of water. Furthermore, the water may be provided at a relatively low pressure, as compared to mains connected toilet systems.

Traditionally diaphragm operated pneumatic pumps are used in vacuum toilet systems for cleaning of toilet pan/bowl, which requires electricity and an electronic controller to be operated, adding to their complexity and cost. Furthermore, the vacuum toilet system may not provide optimum cleaning.

There are various known ways in which to provide toilet systems for cleaning of the toilet pan. US3184761A describes a toilet system where available power from the inlet water pressure is utilized by directing the flow thereof alternatively to the sides of an oscillating piston such that the piston will reciprocate and provide a source of mechanical power. US6082979A describes a vacuum toilet assembly including a vacuum toilet and a vacuum tank. A simple air pump is used to remove air from the tank to create a partial vacuum. The pump comprises an electrically powered reciprocating diaphragm pump.

What is required is a toilet system which provides sufficient cleaning of the toilet pan without consuming large quantities of water and power, and which may operate with limited water pressure and in remote areas.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention relate to a water pressurisation system and to a method of forming a water pressurisation system.

According to an aspect of the invention, there is provided a water pressurisation system comprising: a pneumatic water pump; and a pneumatic actuating valve; wherein the pneumatic water pump defines a water chamber and a pneumatic chamber, an inlet valve adapted to be fluidly couple the water chamber to a water source, and an outlet valve adapted to fluidly couple the water chamber to a toilet pan, the pneumatic chamber having a piston pneumatically separating the pneumatic chamber into a first side and a second side, the piston having a head hydraulically separating the water chamber into a first side and a second side; and wherein the outlet valve is an air pilot operated valve, and the pneumatic water pump is actuated to a primed condition by pneumatically connecting the pneumatic chamber first side to a pneumatic source, and the pneumatic water pump is actuated to a flushed condition by pneumatically connecting the pneumatic chamber second side and the air pilot operated valve to the pneumatic source.

This water pressurisation system is purposed to use for cleaning of toilets with a high pressure water jet using pneumatic air pressure. The system can run with or without electricity. As the water pump is pneumatically driven, at high pressure, water consumption per flush can be reduced to as little as 1 Litre per flush.

The pilot operated valve at the outlet of the pump avoids any leakage in case of high inlet pressure due to high water head, as the outlet valve is only opened upon pressing of flushing valve/switch controlling the pneumatic actuating valve.

The inlet valve may be a non-return valve. The pilot operated valve at the outlet of the pump avoids any leakage in case of failure of a non-return valve.

The pneumatic actuating valve may be a spring return valve. The system therefore does not need an electrical power supply to operate, and is driven by pneumatic power only. The purposed invention does not need any electronic controller to operate. This arrangement further contributes to a low cost system due to there being no electrical controller and no potentially complex electrical maintenance. The system installation and maintenance is relatively easy, as compared to more complex systems employing individual vacuum pumps or electrical motors.

Alternatively, the pneumatic actuating valve may be a solenoid operated valve.

The pneumatic actuating valve may be a directional control valve. The pneumatic actuating valve may be a 5/2 valve. Pneumatic 5/2 valve is used as flushing valve.

The air pilot operated valve may be a 2/2 valve.

The air pilot operated valve may be a non-return valve. The air pilot pressure may be 0 to 4 bar.

The cracking pressure of the non-return inlet valve may be 0.1 bar.

The cracking pressure of the non-return outlet valve may be 0 to 2.5 bar.

According to another aspect of the invention, there is provided a method of forming a water pressurisation system, the method comprising the steps of:
providing a pneumatic water pump having a water chamber and a pneumatic chamber, the pneumatic chamber having a piston pneumatically separating the pneumatic chamber into a first side and a second side, the piston having a head hydraulically separating the water chamber into a first side and a second side; providing a pneumatic actuating valve; fluidly coupling the water chamber to a water source using an inlet valve; fluidly coupling the water chamber to a toilet pan using an outlet valve, wherein the outlet valve is an air pilot operated valve, and pneumatically connecting the pneumatic chamber first side to a pneumatic source to actuate the pneumatic water pump to a primed condition; and simultaneously pneumatically connecting the pneumatic chamber second side and the air pilot operated valve to the pneumatic source to the pneumatic water pump to a flushed condition.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic side elevation of the water pressurisation system in accordance with a first embodiment of the present invention;

Figure 2 is a perspective view of the water pressurisation system of Figure 1 in a primed condition; and

Figure 3 is a perspective view of the water pressurisation system of Figure 1 in a flushed condition.

Figure 4 is a schematic side elevation of the water pressurisation system in accordance with a second embodiment of the present invention;

DETAILED DESCRIPTION

The water pressurisation system 10 has a pneumatic water pump 50, a pneumatic actuating valve 80 and an air pilot operated valve 40.

The pneumatic water pump 50 is a cylinder 52 having a first end wall 54 and a second end wall 56. The cylinder 52 and end walls 52, 54 define a water chamber 60 and a pneumatic chamber 70. The water chamber 60 and a pneumatic chamber 70 are separated by a central wall 58.

The water chamber 60 has an inlet 62 and an outlet 64. A non-return inlet valve 66 is positioned at the inlet 62 of the water chamber 60. A non-return outlet valve 68 is positioned at the outlet 64 of the water chamber 60. The air pilot operated valve 40 is positioned at the outlet 64 of the water chamber 60, downstream of the non-return outlet valve 68.

The pneumatic chamber 70 has an A pneumatic port 72 and a B pneumatic port 74.

Referring briefly to Figure 2, the water pump 50 has a piston 90. The piston 90 has a first end plate 92 and a second end plate 94. The end plates 92, 94 are connected by a tie rod 96. The first end plate 92 is disposed within the water chamber 60 and the second end plate 94 is disposed within the pneumatic chamber 70. The tie rod 96 passes through an aperture 59 provided in the central wall 58. The aperture 59 is centrally aligned within the cylinder 52. The first end plate 92 hydraulically separates the water chamber 60 into a first side and a second side. The second end plate 94 pneumatically separates the pneumatic chamber 70 into a first side and a second side. The first side is exposed to the A pneumatic port 72 and the second side is exposed to the B pneumatic port 74.

The pneumatic actuating valve 80 is a 5/2 valve having five ports and two spool positions. The five ports are as follows:

1. pressurised air input port 81;
2. first pneumatic output port 82;
3. first exhaust port 83 (not shown);
4. second pneumatic output 84 port; and
5. second exhaust port 85 (not shown).

The pneumatic actuating valve 80 is actuated through a mechanical push button 86.

The air pilot operated non return valve 40 is a 2/2 valve having an inlet port 44 and an outlet port 46. Pilot port C 42 is used to control flow between the inlet port 44 and outlet port 46.

Hydraulic Connections

The water pressurisation system 10 is fluidly connected to a water source, for example an overhead tank 20 by pipe 21. The water pressurisation system 10 is fluidly connected to a toilet pan 30 by pipe 22.

Pneumatic Connections

The pneumatic actuating valve 80 is fluidly connected to a source of pressurised air, for example a pneumatic pump 25, by pneumatic line 26.

The first pneumatic output port 82 is fluidly connected to the A pneumatic port 72 of pneumatic chamber 70 by pneumatic line 27. The second pneumatic output port 84 is fluidly connected to the B pneumatic port 74 of pneumatic chamber 70 and to the pilot port C 42 of air pilot operated valve 40 by pneumatic line 28.

Operation

The water pressurisation system 10 uses the pneumatic water pump 50 to draw water from the water source 20 and pump the drawn water to a toilet pan 30 in a double acting manner.

Primed Condition

Referring to Figure 2, the piston 90 is actuated in a backward stroke so as to draw water from the water source 20 as follows:

The first pneumatic output port 81 is fluidly connected to the A pneumatic port 72 of pneumatic chamber 70 and the B pneumatic port 74 of pneumatic chamber 70 is connected to exhaust such that air flows into the first side of the pneumatic chamber 70 and drives the second end plate 94 towards the second end wall 56. The piston 90 thereby moves to the right (backward stroke), and due to the tie rod 96 connection to the first end plate 92, the first end plate 92 is pulled towards the central wall 58. Movement of the first end plate 92 within the water chamber 60 creates a vacuum effect to overcome the cracking pressure of the inlet valve 66 and draw water from the water source 20 into the first side of the water chamber 60. The pneumatic water pump 50 is thus actuated to a primed condition.

A non-return valve allows the fluid to flow from one side and restricts the reverse flow. Cracking pressure of a non-return valve is the minimum value of pressure upon which the flow path opens and flow starts. The cracking pressure is usually defined by the tension of spring used within the non-return valve. The non-return inlet valve 66 has a cracking pressure of 0.1bar. At this pressure, which is created due to suction created in backward stroke of the piston 90, the non-return inlet valve 66 opens. Opening of the non-return inlet valve 66 allows water to enter into water chamber 60 from overhead tank 20 via inlet 62. The same non-return inlet valve 66 restricts the reverse flow of water from the water chamber 60 to the overhead tank 20. The non-return inlet valve 66 is a normally closed type valve.

Flushed Condition

Referring to Figure 3, the piston 90 is actuated in a forward stroke so as to drive water from the water chamber 60 to the toilet pan 30 as follows:

The second pneumatic output port 84 is fluidly connected to the B pneumatic port 74 of pneumatic chamber 70 and to the pilot port C 42 of air pilot operated non return valve 40, and the first pneumatic output port 81 is fluidly connected to exhaust such that air flows into the second side of the pneumatic chamber 70 and drives the second end plate 94 towards the central wall 58. The piston 90 thereby moves to the left, and due to the tie rod 96 connection to the first end plate 92, the first end plate 92 is pushed towards the first end wall 54. Movement of the first end plate 92 within the water chamber 60 drives the water towards the outlet valve 68 and overcomes the cracking pressure of the outlet valve 68 and air pilot operated valve 40 and thereby delivers the water towards the toilet pan 20. The pneumatic water pump 50 is thus actuated to a flushed condition.

The non-return outlet valve 68 has a cracking pressure of 0.8bar. This pressure is generated during the forward stroke of the piston 66. Opening of the non-return outlet valve 68 allows water to exit from water chamber 60 to the toilet pan 30. The same non-return outlet valve 68 restricts the reverse flow of air from pan side to water barrel during the backward stroke.

Ideally non-return outlet valve 68 does not allow the water to flow until the water pump 50 actuates and creates a minimum pressure of 0.8bar. But in some cases the non-return outlet valve 68 may fail to do so due to external factors such as vibration or contamination. In that case water may begin to leak to the pan 30. However, the air pilot operated valve 40 may be used in addition to or instead of the non-return outlet valve 68 to prevent any such leakage.
The air pilot operated valve 40 remains closed and restricts any water leakage and opens only when the pneumatic pressure enters into it. Pneumatic actuating valve 80 supplies pressurised air to the pneumatic chamber 70 and same pneumatic line 28 is tapped to pilot port C 42 of the air pilot operated valve 40 pilot port to open the air pilot operated valve 40.

In an alternative embodiment, the non-return outlet valve 68 is a normally open type valve.

The air pilot operated valve 40 also prevents water leakage to the pan 20 in cases when the inlet line pressure (pipe 21) is higher than the non-return inlet valve 66 and non-return outlet valve 68 cracking pressures. The air pilot operated valve 40 restricts the water flow irrespective of water pressure up to practical limitations. Water will not flow without air signal to the air pilot operated valve 40. In practice, this makes the system workable up-to 8 bar inlet water pressure.

Referring to Figure 4, a water pressurisation system 210 is shown in accordance with a second embodiment of the present invention. The water pressurisation system 210 of Figure 4 shares many of the same features as the water pressurisation system 10 of Figure 1, and as such only the significant differences shall be described in detail. Furthermore, similar reference numerals shall be used to denote similar features, prefixed by a "2" to denote that those features are described in reference to the water pressurisation system 210 of Figure 4.

The water pressurisation system 210 has a pneumatic water pump 250, a pneumatic actuating valve 280 and an air pilot operated valve 240.

The pneumatic actuating valve 280 is a solenoid operated 5/2 valve, and is represented in Figure 4 using schematics. The pneumatic actuating valve 280 is actuated through an electrical push button 287. The electrical push button 287 is controlled and powered by power source/controller 289.

In alternate embodiments, the electrical push button 287 may be replaced by a lever, a rotary knob, a solenoid or an air pilot operated button.