Automatic oil return structure for piston pump

An automatic oil return structure for a piston pump comprising:

• an oil storage container;
• a piston spaced apart from the oil storage container and comprising:
• an oil storage chamber;
• a main body assembly mounted between the oil storage container and the piston and comprising:
• at least one main channel communicating with the oil storage container;
• at least one oil-plug channel, the at least one main channel communicating with the oil storage chamber of the piston via the at least one oil-plug channel;
• at least one oil blocking assembly mounted in the at least one oil-plug channel and selectively blocking the at least one oil-plug channel;
• a pressure regulating channel communicating with the at least one main channel;
• a controlling channel communicating with the pressure regulating channel;
• a block controlling assembly mounted in the controlling channel and selectively blocking the controlling channel;
• a communicating channel communicating with the controlling channel;
• an operating channel communicating with the communicating channel;
• a controlling assembly mounted in the operating channel, and selectively blocking the operating channel;
• a minor channel, the at least one main channel communicating with the operating channel via the minor channel;
• an oil returning channel communicating with the oil storage container, the operating channel, and the at least one oil-plug channel;
• wherein when a pressure of the at least one main channel is larger than a starting pressure, the pressure of the at least one main channel makes the at least one oil blocking assembly open, such that the at least one main channel communicates with the oil storage chamber of the piston;
• at the same time, the at least one oil blocking assembly isolates the oil storage chamber of the piston from the oil returning channel;
• at the same time, the block controlling assembly blocks the controlling channel and thereby isolates the pressure regulating channel from the communicating channel;
• at the same time, the controlling assembly blocks the operating channel and thereby isolates the oil returning channel from the minor channel;
• when the pressure of the at least one main channel achieves a limited pressure, the pressure of the at least one main channel pushes the block controlling assembly away and thereby the pressure regulating channel communicates with the communicating channel, and pushes the controlling assembly away and thereby the minor channel communicates with the oil returning channel;
• at the same time, a pressure of the oil storage chamber of the piston pushes the at least one oil blocking assembly to isolate the oil storage chamber of the piston from the at least one main channel, and then the oil storage chamber of the piston communicates with the oil returning channel;
• the limited pressure is larger than the starting pressure.