Proportional valve

The proportional valve comprises a valve body, a main valve element and a mechanical pilot valve assembly, the valve body is provided with a cavity, the main valve element is movably arranged in the cavity, a main valve element control cavity is formed between the tail of the main valve element and the inner wall of the cavity, and the mechanical pilot valve assembly comprises a pilot valve body, a first valve element, a second valve element and a driving assembly. The pilot valve body is provided with a liquid supply channel and a liquid return channel which are communicated with the main valve element control cavity, the first valve element can control on-off of the liquid supply channel, the second valve element can control on-off of the liquid return channel, and the axis of the first valve element and the axis of the second valve element are collinear. The first driving rod is transversely arranged between the first valve element and the second valve element, the second driving rod is rotationally connec