초록 ▼

Disclosed is a fan drive, in particular one for cooling installations of rail vehicles. The fan drive comprises a hydraulic motor and a control valve which regulates a bypass as a function of temperature, thus affecting the flow of a pressure medium driving the motor. The control valve comprises a c

Disclosed is a fan drive, in particular one for cooling installations of rail vehicles. The fan drive comprises a hydraulic motor and a control valve which regulates a bypass as a function of temperature, thus affecting the flow of a pressure medium driving the motor. The control valve comprises a control piston subjected to a control pressure in the direction of closing the bypass, and a counterbalancing pressure in the opposite direction from the source of the pressure medium. The control valve also comprises a control spring which biases the control piston in the direction of closing the valve, and a pilot valve which affects the control pressure. The pilot valve is actuated by an electromechanical servo component. The pilot valve is located in an insert which is arranged within the control piston. A central bore of the control piston is slidingly guided on the convex surface of the insert so as to form a seal.

대표청구항 ▼

A fan drive suitable for a cooling installation of a vehicle, comprising: (a) a hydraulic motor which is actuated by a pressure medium; (b) a bypass for detouring the flow of pressure medium around the hydraulic motor; (c) a control valve which regulates the flow of pressure medium to the bypass and

A fan drive suitable for a cooling installation of a vehicle, comprising: (a) a hydraulic motor which is actuated by a pressure medium; (b) a bypass for detouring the flow of pressure medium around the hydraulic motor; (c) a control valve which regulates the flow of pressure medium to the bypass and to the hydraulic motor wherein said control valve comprises a control piston for opening and closing said bypass and having a central bore, an insert upon which the central bore of the control piston is slidingly arranged so as to form a seal, a front surface of the control piston facing the direction of closing said bypass which is acted upon by the pressure medium, a back surface of the control piston facing away from the direction of closing said bypass which is also acted upon by the pressure medium wherein the pressure acting on the front side of the control piston is the full pressure of the pressure medium called the high-pressure, and the pressure of the pressure medium acting on the back side of the control piston is called the control pressure, a control spring for biasing the control piston in the direction of closing said bypass, and a control cylinder for slidably containing the control piston which is divided by said piston into a high-pressure section in front of said front surface and a control chamber in back of said back surface; (d) a pilot valve, arranged in said insert, which functions to regulate said control pressure; and (e) an electromechanical servo element for actuating said pilot valve.