Hydraulic fan drive

Abstract

A hydraulic fan drive includes a hydraulic pump that has an adjustable swept volume. The hydraulic pump is assigned a pressure control valve arrangement that is configured to regulate a pump pressure by adjustment of the swept volume. The drive further includes a hydraulic motor configured to drive an impeller wheel and a pressure line, which is connected to a pressure input of the hydraulic motor and into which pressure medium is configured to be conveyed by the hydraulic pump. A hydraulic accumulator is connected to the pressure line and the displacement of the hydraulic motor is configured to be adjusted. Energy is buffer-stored by the hydraulic accumulator by feeding in pressure medium beyond the amount that is displaced by the hydraulic motor. This stored energy becomes free for other operations of a machine, for example, to which the drive is attached.

1 . A hydraulic fan drive, comprising:
 a hydraulic pump of defining an adjustable swept volume, the hydraulic pump being assigned a pressure control valve arrangement configured to regulate a pump pressure by adjustment of the swept volume,   a hydraulic motor configured to drive a fan impeller, the hydraulic motor having an adjustable displacement,   a pressure line, which is connected to a pressure port of the hydraulic motor and into which pressure medium is configured to be delivered by the hydraulic pump and   a hydraulic accumulator connected to the pressure line.   
     
     
         2 . The hydraulic fan drive as claimed in  claim 1 , wherein the setting of the pressure control valve arrangement is configured to be varied by remote control. 
     
     
         3 . The hydraulic fan drive as claimed in  claim 1 , further comprising a check valve arranged between the hydraulic pump and a section of the pressure line to which the hydraulic accumulator is connected, the check valve being configured to close toward the hydraulic pump. 
     
     
         4 . The hydraulic fan drive as claimed in  claim 1 , further comprising a branch line, via which pressure medium is configured to be fed into the pressure line independently of the hydraulic pump, the branch line opening into the pressure line. 
     
     
         5 . The hydraulic fan drive as claimed in  claim 4 , further comprising a check valve opening toward the section of the pressure line in the branch line. 
     
     
         6 . The hydraulic fan drive as claimed in  claim 1 , wherein the hydraulic pump is configured to be operated as a hydraulic motor while retaining the direction of rotation. 
     
     
         7 . The hydraulic fan drive as claimed in  claim 6 , wherein the hydraulic pump configured to be adjusted via zero and is further configured to be operated as a hydraulic motor with the same pressure port and the same direction of rotation. 
     
     
         8 . The hydraulic fan drive as claimed in  claim 1 , wherein the hydraulic motor is assigned a torque control valve arrangement configured to regulate a motor torque by adjusting the displacement. 
     
     
         9 . The hydraulic fan drive as claimed in  claim 8 , wherein the torque control valve arrangement has a valve piston which is acted upon by a force that is configured to be varied by remote control so as to increase the displacement of the hydraulic motor and is supported at an at least approximately fixed distance from an axis of rotation on a lever, wherein a pressure force dependent on the pressure in the pressure line and acting on the valve piston so as to reduce the displacement acts on the lever in the opposite direction, and wherein the distance of the point of introduction of the pressure force into the lever from the axis of rotation thereof depends on the position of an adjusting piston of the hydraulic motor and on the displacement of the hydraulic motor. 
     
     
         10 . The hydraulic fan drive as claimed in  claim 1 , wherein the hydraulic motor is assigned a control valve arrangement by which the displacement of the hydraulic motor is configured to be varied proportionally to a control signal, and wherein the control signal is dependent, on a setpoint speed value of the hydraulic motor and on a detected speed of the hydraulic motor or on the detected pressure in the pressure line and in the hydraulic accumulator. 
     
     
         11 . The hydraulic fan drive as claimed in  claim 1 , wherein the hydraulic accumulator is connected directly to the pressure line.