Oil drain valve, energy accumulation device, hydraulic system and working machine

An oil drain valve, comprising a valve body, a valve core and an elastic element;

• wherein
• the valve body is provided with a first oil port and a second oil port, and the valve core is provided between the first oil port and the second oil port;
• the valve core is communicated with the first oil port and the second oil port, and the valve core is movable in the valve body to switch from a first working position to a second working position;
• the elastic element is provided between a first end of the valve core and the valve body, the first end of the valve core is communicated with the first oil port, and a second end of the valve core is communicated with the second oil port;
• in response to that hydraulic oil in the oil drain valve flows from the first oil port to the second oil port, the valve core is configured to switch from the second working position to the first working position under an action of the elastic element;
• in response to that the hydraulic oil in the oil drain valve flows from the second oil port to the first oil port, the valve core is configured to compress the elastic element and switch from the first working position to the second working position;
• and
• a flow quantity of the oil drain valve in response to that the valve core operates in the second working position is less than a flow quantity of the oil drain valve in response to that the valve core operates in the first working position.