1. Field of the Invention
This invention relates to a pressure vessel for a toilet, particularly to one that able to guide pressured water into a drain valve so as to open it for flushing the toilet.
2. Description of the Prior Art
Commonly, a conventional vessel used for a toilet to carry out flushing is based on gravity force and water level drop, which, actually, are not strong enough to flush down, always needing more water to clean up the toilet, causing a waste of water. In order to be more economic, a pressure vessel has been invented to overcome such a disadvantage. The pressure vessel is mainly installed with an airtight vessel inside it, provided with a drain valve. When water flows into the airtight vessel, air in the airtight vessel is to be compressed to store up some pressure energy that is to strongly enhance extra force, plus the gravity force and the water level drop, to obtain more complete and cleaner flushing when the piston of the drain valve is raised up to keep a water exit opened for releasing the pressurized water in the pressure vessel, able to achieve a good flushing effect with even less water. Such a pressure vessel is disclosed in a U.S. Pat. No. 4,233,698 that includes an airtight vessel, an air and water entry device, a drain valve, a controlling valve and a water entry valve for supplying a pressure for the drain valve. The conventional pressure vessel has still disadvantages as described below.
1. The moment when the drain valve is opened, water in the drain valve to be rushed down is still too less to carry out flushing.
2. If water in the drain valve is to be dropped down for washing, a pressing device on the top has to be pressed down to enable the drain valve to open. In practice, it needs a considerable force to press down the pressing device initially because a strong rebounding force possessed by a compressed spring in the drain valve must be surpassed, inconvenient for operation.
Next, another pressure auxiliary double flushing system disclosed in a U.S. patent No. 2004/0194200 can, though, solve the disadvantages mentioned above, it has a very complicated structure, difficult for assembly and having a high cost. Relatively, it has a higher possibility of breakdown. Also, the pressure vessel of the pressure auxiliary double washing system is to be filled with water until the water exit of the drain valve is completely sealed by a piston in the pressure vessel pressed down by the pressured water rushing into the drain valve. So, it is to take a longer time, about 10 seconds, than a regular pressure vessel for refilling the vessel, having to wait a while for next use. In addition, because the pressure auxiliary double washing system is operated via releasing the pressured water from the drain valve to enforce the piston to move up and disclose the water exit for water to flush down, therefore, the drain valve is as well to move upwards mistakenly to release water if a pressure releasing tube communicated with the drain valve is damaged or leaking, possible to cause a waste of water source.