LAVATORY UNIT

Abstract

A lavatory unit (10) comprising a tank body (12) connected to a pressurised water supply (20), and flushing means (14, 21, 23) for releasing water from the tank body via an outlet to a lavatory bowl (11). The flushing means includes an elastic bladder (21) the interior of which is in communication with the tank, the tank being generally sealed otherwise, such that the bladder stressed with the expansion of air forced from the tank as the tank fills with water and the bladder relaxes elastically as the tank empties, and thereby assists in ejecting the water under pressure from the tank to provide a better flushing action.

Description

This invention relates to lavatory or WC tanks.

In a conventional lavatory a tank is mounted above a bowl having a U-bend trap and a flush mechanism is used to release water from the bowl under gravity and thereby clean waste solids or liquids from the bowl.

Typically, in order to properly flush the bowl, significant quantities of water are required—for example 7-10 litres per flush. This leads to very high water consumption levels and correspondingly high sewage treatment requirements.

The present invention aims to provide an improved lavatory tank having significantly lower water consumption requirements without any decrease in efficiency.

The invention provides a lavatory tank comprising a tank body, means for connecting the tank body to a pressurised liquid supply, and means for releasing liquid from the tank body via an outlet, wherein said releasing means includes an elastic means which becomes stressed as the tank fills with liquid and which becomes relaxed as the tank empties.

The stored energy in the elastic means provides a higher water velocity from the tank outlet, which in turn enables a lower volume of water to achieve the same flushing efficiency as is achieved from a conventional tank (which releases water under gravity).

Preferably, the elastic means comprises an expandable-contractible member the interior of which is in communication with defining an internal space which is in communication with the interior of the tank, whereby as liquid fills the tank it displaces gas from the empty tank to expand said internal space.

In preferred embodiments, the elastic means is an air-filled bladder connected to a sealed water tank. In such embodiments the air located in the water tank (when empty) is forced by the pressure of the incoming water into the internal space defined by the bladder. Thus, the tank interior and bladder interior form a closed system connected to the exterior by a release or flush valve and connected also to the pressurised water supply.

The invention also provides a lavatory unit comprising a lavatory tank as described herein and a lavatory bowl connected to the tank via the tank outlet.

Preferably, the bowl comprises a substantially cylindrical section adapted to hold a volume of water is normal use and a flared section extending from a narrow diameter portion, defined by the top of the cylindrical section, to a wide diameter portion, defined by the mouth of the bowl, the water level being maintained in normal use in the cylindrical section at least 5 cm below the flared section.

Suitably the cylindrical section leads to a U-shaped trap. When the bowl is flushed with water emerging from the tank at high velocity, water tends to fill the cylindrical section more quickly than the trap can empty, thereby building up a head of water which helps remove solids from the trap as it empties.

The invention will now be further illustrated by the following description of an embodiment thereof, given by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a side sectional elevation of a lavatory unit according to the invention;

FIG. 2 is a front sectional elevation of a detail of the lavatory unit of FIG. 1, shown after flushing; and

FIG. 3 is a front sectional elevation of a detail of the lavatory unit of FIG. 1, shown before flushing

In FIG. 1 there is indicated, generally at 10, a lavatory unit according to the invention, comprising a bowl 11 connected to a water tank 12 by a flush pipe 13 having a flush valve 14 (described in greater detail below).

Bowl 11 comprises a flared section 15 and a cylindrical section 16 above a conventional U-bend trap 17. The water level 18 in the trap 17 lies at least 5 cm below the top 19 of the cylindrical section, (preferably at least 7.5 cm).

FIG. 2 shows the water tank 12 in greater detail. Tank 12 is fed by a feed pipe 20 connected to a pressurised water supply such as a domestic cold water tank or a water mains (which is suitably pressure controlled). The interior is also in communication with an air bladder 21 mounted in a support housing 22 above the tank 12. Support housing 22 is open to the atmosphere allowing bladder 21 to freely expand and contract.

The tank 12 and bladder 21 are shown at the end of flushing: the tank 12 is empty, i.e. air-filled, and the flush valve 14 is open having allowed the water originally held in tank 12 to escape via the flush pipe 13.

Flush valve 14 is a ball valve which controls the flow through both flush pipe 13 and feed pipe 20; when flush pipe 14 is open, feed pipe 20 is closed and vice versa.

A handle 23 (FIG. 1) controls the position of valve 14, and a spring-loaded means (not shown) biases the handle 23, and thus the valve 14, to the position shown in FIG. 3, wherein the flush pipe 13 is closed and the feed pipe 20 is open, allowing the tank 12 to refill.

FIG. 3 shows the tank 12 at equilibrium, filled with water 24. The entry of water 24 under pressure has displaced the air within the tank 12 into bladder 21 which is elastically expanded. Accordingly, when flush valve 14 is actuated, the stored energy of the pressurised air in the bladder 21 is released to force the water 24 through the flush pipe 13. In this way, the velocity of flushing water is greatly increased relative to conventional systems which rely on gravity only to release water to the bowl.

Because of the increased velocity of flush water, aided by the bowl design (discussed further below), a greatly reduced volume of water can accomplish satisfactory flushing. In tests it has been found that tanks according to the invention containing between 2 and 2.5 litres will accomplish the same flushing action as a conventional tank of from 7 to 10 litres.

The bladder can be of an elastic strength chosen to meet the local water pressure and can, for example, be concertina-shaped or elastically expandable (as shown). Other suitable elastic means may also be used.

Referring back to FIG. 1, it can be seen that whereas a conventional bowl has an internal overhang around the rim from under which the flush water emerges, the bowl 11 of the illustrated embodiment has a simple rim 26. Water emerges from the mouth 25 of flush pipe 13 at a sufficient velocity to completely cleanse the interior 27 of bowl 11.

The shape and dimensions of the bowl 11 and the angle and diameter of the flush pipe 13 are chosen to ensure complete cleansing of the bowl's interior 27 without water splashing over the rim 26.

For example, a bowl having the dimensions indicated below (see FIG. 1) was found to be optimally flushed with a flush pipe entering at a=100°:

b = 15 cm
c = 8 cm
d = 15 cm
e = 35°
f = 37°
g = 3 cm

These dimensions are interrelated, and the angle a will also depend on the resilience of the bladder 21, and hence the water velocity.

When flush water enters the bowl, it tends to build up above water level 18 before the pressure of this head of water causes the water in either side of the U-bend to equalise. This action assists in more thorough flushing of the bowl and can be attributed to the bowl shape whereby the length of cylindrical section 16 above water level 18 generates a greater head of pressure than in a conventional bowl having a larger water surface area.

In an alternative embodiment of bowl, a trap-door is located at the end of cylindrical section 16, allowing the waste in the toilet bowl to be flushed directly into the sewer pipe without a U-bend. In this embodiment, a venting pipe is provided in the sewer pipe below and adjacent to the trap door, to allow noxious odours to escape from the sewer pipe. The trap door is suitably activated by a linkage extending from the flush handle 23.

Claims

1. A lavatory tank comprising a tank body, means for connecting the tank body to a pressurised liquid supply, and means for releasing liquid from the tank body via an outlet, wherein said releasing means comprises an elastic means which becomes stressed as the tank fills with liquid and which becomes relaxed as the tank empties.

2. A lavatory tank according to claim 1, wherein said elastic means comprises an expandable-contractible member defining an internal space which is in communication with the interior of the tank, whereby as liquid fills the tank it displaces gas from the empty tank to expand the said internal space.

3. A lavatory tank according to claim 2, wherein said expandable-contractible member is chosen from one of the following: a flexible elastic bladder, a concertina-like flexible member.

4. A lavatory tank according to claim 2, wherein said expandable-contractible member is mounted within a support housing, said support housing defining an internal chamber, said internal chamber defining the maximum expansion of said expandable-contractible member.

5. A lavatory tank according to claim 4, wherein at least one aperture is defined on said support housing, said at least one aperture extending from said internal chamber of said support housing to the exterior of said support housing.

6. A lavatory tank according to claim 1, wherein said lavatory tank further comprises a four way ball valve, said means for connecting the tank body to a pressurised liquid supply coupled to said ball valve, said releasing means further coupled to said ball valve.

7. A lavatory tank according to claim 1, wherein said releasing means further comprises a sluice valve coupled to said outlet.

8. A lavatory unit comprising a tank according to claim 1, and a lavatory bowl connected to the tank via the tank outlet.

9. A lavatory unit according to claim 8, wherein the bowl comprises a substantially cylindrical section and a flared section, said cylindrical section adapted to hold a volume of water in normal use, said flared section extending from a narrow diameter portion, defined by the top of the cylindrical section, to a wide diameter portion, defined by the mouth of the bowl.

10. A lavatory unit according to claim 9, wherein the water level is maintained in normal use in the cylindrical section at least 5 cm below the flared section.

11. A lavatory unit according to claim 9, wherein said cylindrical section is coupled to a U-bend trap.

12. A lavatory unit according to claim 9, wherein said lavatory unit further comprises a trap-door, said cylindrical section coupled to said trap door.

13. A lavatory unit according to claim 9, wherein the ratio of the height of said cylindrical section to the height of said flared section is between 4:3 to 5:3, wherein the angle of incline of said flared section is between 30°-40°, and wherein said tank outlet enters into the flared section of said bowl at an angle of between 5°-15°.

14. A lavatory unit according to claim 13, wherein the height of said cylindrical section is approximately 23 cm, wherein the height of said flared section is approximately 15 cm, wherein the tank outlet comprises a tube having a diameter of approximately 3 cm, the angle of entry of said tube into said flared section approximately 10°, and wherein the angle of incline of said flared section varies from 37° at that portion of the flared section immediately adjacent the point of entry of said tube into the flared section to 35° at that portion of the flared section directly opposite the point of entry of said tube into the flared section.