End cover and four-way reversing valve using the same and assembling method thereof

An assembling method of a four-way reversing valve, comprising steps of fixedly connecting a pilot valve with a valve body of a main valve by welding, assembling components including a slider, a link and a piston, and fixedly connecting an end cover with the valve body by welding, the end cover having a larger diameter section and a smaller diameter section sequentially provided in an axial direction, wherein an outer periphery of the larger diameter section of the end cover is tightly connected with the valve body, and an end portion of the smaller diameter section of the end cover is fitted with a piston of the main valve so as to define an operating position of the piston, characterized in that the end cover and an end portion of the valve body are connected by argon welding, laser welding or high energy-dense beam welding,

• wherein the larger diameter section of the end cover has a frustum shape with a larger outer end and smaller inner end, and an interference fit is formed between the outer end of the larger diameter section of the end cover and an inner wall of the valve body;
• and
• wherein the larger outer end of the larger diameter section of the end cover has a radial dimension greater than an inner diameter of the end portion of the valve body, and the smaller inner end of the larger diameter section of the end cover has a radial dimension smaller than the inner diameter of the end portion of the valve body;
• and
• the larger diameter section of the end cover is configured to be subjected to a radially inward extrusion force during assembly of the end cover onto the valve body and to be foldingly deformed inwardly as a whole around the smaller diameter end of the end cover under the action of the radially inward extrusion force, so as to abut against the inner wall of the valve body.