Abstract: A high-pressure gas filling and unloading system has a high-pressure gas pipeline for connecting to a gas filling station, a displacement gas pipeline for gas displacement, a plurality of double-channel rotating joints provided in said high-pressure gas pipeline and configured to be rotatable under pressure, and a filling and unloading joint provided at a free end of said high-pressure gas pipeline and comprising a control mechanism. The filling and unloading joint is configured to form a displacement working channel or a filling and unloading working channel therein through the control mechanism. The control mechanism is configured to alternately open the displacement working channel and the filling and unloading working channel, so that the displacement working channel is in communication with the displacement gas pipeline for gas displacement, or the filling and unloading working channel is in communication with the high-pressure gas pipeline for filling and unloading of high-pressure gas.

Abstract: A high-pressure gas filling and unloading system has a high-pressure gas pipeline for connecting to a gas filling station, a displacement gas pipeline for gas displacement, a plurality of double-channel rotating joints provided in said high-pressure gas pipeline and configured to be rotatable under pressure, and a filling and unloading joint provided at a free end of said high-pressure gas pipeline and comprising a control mechanism. The filling and unloading joint is configured to form a displacement working channel or a filling and unloading working channel therein through the control mechanism. The control mechanism is configured to alternately open the displacement working channel and the filling and unloading working channel, so that the displacement working channel is in communication with the displacement gas pipeline for gas displacement, or the filling and unloading working channel is in communication with the high-pressure gas pipeline for filling and unloading of high-pressure gas.

Abstract: Some embodiments of the disclosure provide a method for measuring orthogonality of an orthogonal axis system, In some examples, the method includes following steps: placing an instrument on a bearing surface, intercepting a second rotary axis along an interception plane to obtain a first virtual cross section of the second rotary axis, and measuring the first virtual cross section to obtain a geometric center of the first virtual cross section as a first position; rotating a first rotary device to enable the second rotary axis to rotate with a preset angular degree, and measuring the second virtual cross section to obtain a geometric center of the second virtual cross section as a second position; and determining whether the orthogonality between the first rotary axis and the second rotary axis meets requirements or not on the basis of the first position and the second position.