Railway wagon brake cylinder pressure control device and method

The invention belongs to the technical field of railway vehicle air brake systems, and particularly relates to a railway wagon brake cylinder pressure control device and method. The device comprises a valve body, a first valve rod is arranged in the valve body, second valve rods are arranged on the upper portion and the lower portion in the valve rod, a valve seat is fixed in the lower section of the valve body, a sandwich valve is further arranged in the valve body in a sleeved mode, a cavity in the upper side of the valve rod is communicated with a train pipe, and an annular cavity is formed between the valve rod and the valve body and communicated with a brake cylinder. The lower side of the annular cavity is communicated with an air inlet cavity, the air inlet cavity is communicated with the auxiliary air cylinder, the cavity on the lower side of the valve seat is communicated with the emergency air cylinder, and a first small hole is formed in the first valve rod. The sectional area of the first small ho