Drain valve

A water tank of a toilet, the water tank comprising a drain valve,

• the drain valve comprising:
• a valve body;
• a valve seat mounted below the valve body;
• and
• an overflow pipe located in the valve body and configured to move up and down relative to the valve body,
• wherein the valve seat comprises a drainage channel,
• wherein the overflow pipe comprises a blocking element and a flow rate regulator below the blocking element,
• wherein the overflow pipe is configured to be in an initial state or a raised state and configured to be switched between the initial state and the raised state,
• wherein when the overflow pipe is in the initial state, the blocking element seals a channel water inlet of the drainage channel, and the flow rate regulator is located in the drainage channel,
• wherein when the overflow pipe is in the raised state, the blocking element leaves the channel water inlet, the flow rate regulator is partially or completely located above the channel water inlet, and a water flow channel is formed between the flow rate regulator and the channel water inlet,
• wherein when the water flow channel is formed, water enters a toilet bowl from the channel water inlet and the drainage channel,
• wherein a connector is disposed at a lower end of the overflow pipe, and
• wherein the flow rate regulator is clamped with the connector.

A method for controlling water to drain from a water tank by using a drain valve, the method comprising:

• selecting a flow rate regulator comprising a replacement part according to a demand for a drainage speed;
• connecting the selected flow rate regulator to an overflow pipe of the drain valve;
• setting, by a processor, the overflow pipe in an initial state by driving the overflow pipe to move down relative to a valve body of the drain valve so that a blocking element of the drain valve seals a channel water inlet of a drainage channel of the drain valve;
• determining, by the processor, whether to open the drainage channel;
• and
• when determining that the drainage channel should be opened, switching, by the processor, the overflow pipe from the initial state to a raised state so that the blocking element leaves the channel water inlet, the selected flow rate regulator is partially or completely located above the channel water inlet, and a water flow channel is formed between the selected flow rate regulator and the channel water inlet,
• wherein connecting the selected flow rate regulator to the overflow pipe of the drain valve comprises:
• clamping the selected flow rate regulator with a connector disposed at a lower end of the overflow pipe.