题厕所的坐便器在冲水之后由自来水自动上水,当水箱内的水达到一定深度时,浮标带动杠杆压住进水口,停止上水(图1).有一种水箱的浮标,形状是中间有隔断的圆柱体,隔断的中部有一小孔通过塑料管连在一个阀门上(图2).阀门安装在便器坐圈的下面,平时是闭合的,当坐圈落在坐便器上并受到压力时阀门打开,塑料管与大气相通。(1)说出这种设计的目的.(2)说出这种设计的工作原理,特别要指 The toilet in the toilet is automatically filled with tap water after flushing. When the water in the tank reaches a certain depth, the buoy pushes the lever against the inlet and stops the water supply (Figure 1). There is a buoy for the water tank, the shape is the middle There is a partitioned cylinder, a small hole in the middle of the partition is connected to a valve through a plastic pipe (Figure 2). The valve is installed under the toilet seat, usually closed, when the seat falls on the toilet and is under pressure When the valve opens, the plastic tube is open to the atmosphere. (1) Say the purpose of this design. (2) Say the working principle of this design, especially refer to