Abstract: An outdoor unit of an air-conditioner and two-pipe and three-pipe air-conditioning systems having the same are provided. The outdoor unit includes a compressor defining an outlet and an inlet; a first four-way valve defining a first valve communicated with the outlet, second and third ports communicated with the inlet; a second four-way valve defining second and third ports communicated with the inlet; an outdoor heat exchanger defining a first refrigerant valve Communicated with the fourth port of the first four-way valve; a first gas pipe defining a first end connected with the second and third ports of the first and second four-way valves and, the inlet; a second gas pipe defining a first end connected with the fourth port of the second four-way valve; a third gas pipe defining a first end connected with the outlet and a second end connected with the first port of the second four-way valve.

Abstract: A damping device for a stay cable including a rotating lever, a lever support saddle, a longitudinal connecting member, and a rigid connection rod. When the stay cable vibrates inside or outside the plane thereof, the vibration displacement is transferred to the rotating lever through the rigid connection rod. One end of the rotating lever is connected to the lever support saddle via the longitudinal connecting member, and can rotate up and down with the lever support saddle as the axis and rotate around its central axis. The other end of the rotating lever is connected to a mass block and a damper. The damping device effectively inhibits vibrations inside and outside the stay cable plane, is easy to install and maintain, and does not negatively impact the appearance of a cable-stayed bridge.

Abstract: A damping device for a stay cable including a rotating lever, a lever support saddle, a longitudinal connecting member, and a rigid connection rod. When the stay cable vibrates inside or outside the plane thereof, the vibration displacement is transferred to the rotating lever through the rigid connection rod. One end of the rotating lever is connected to the lever support saddle via the longitudinal connecting member, and can rotate up and down with the lever support saddle as the axis and rotate around its central axis. The other end of the rotating lever is connected to a mass block and a damper. The damping device effectively inhibits vibrations inside and outside the stay cable plane, is easy to install and maintain, and does not negatively impact the appearance of a cable-stayed bridge.