Hydraulic Circuit Supply System

Abstract

The invention relates to an system for supplying a hydraulic circuit with hydraulic fluid. The system includes a working reservoir and an auxiliary reservoir connected to the working reservoir by a hydraulic line. An air pump has an inlet connected to a suction line that opens into a liquid-free portion of the auxiliary reservoir so that a negative pressure can be built up in the auxiliary reservoir relative to the atmospheric ambient pressure. The air pump inlet is also connected to a control line, which comprises a control opening which is covered by the hydraulic fluid in the working reservoir, at least before the air pump is started up.

1 . A supply system for supplying a hydraulic circuit with hydraulic fluid, comprising:
 a working reservoir for holding hydraulic fluid for operating the hydraulic circuit;   an auxiliary reservoir, connected to the working reservoir via a hydraulic line, the auxiliary reservoir providing interim storage of hydraulic fluid removed from the working reservoir; and   an air pump, the air pump having an inlet connected to a suction line issuing into a fluid-free area of the auxiliary reservoir, so that relative to atmospheric ambient pressure, a negative pressure can be built up in the auxiliary reservoir, and the air pump inlet also being connected to a control line having a control opening which is covered by the hydraulic fluid in the working reservoir, at least before the air pump goes into operation.   
     
     
         2 . The supply system of  claim 1 , wherein:
 the hydraulic line runs between a lower portion of the working reservoir and a lower portion of the auxiliary reservoir.   
     
     
         3 . The supply system of  claim 1 , wherein:
 the suction line is directly connected to the control line.   
     
     
         4 . The supply system of  claim 1 , wherein:
 the control opening is formed in the control line as a circular or slit-shaped inlet.   
     
     
         5 . The supply system of  claim 1 , wherein:
 the control opening is formed in a terminal portion of the control line projecting into the working reservoir.   
     
     
         6 . The supply system of  claim 5 , wherein:
 several control openings are formed in the terminal portion of the control line projecting into the working reservoir, wherein the control openings are arranged one above another.   
     
     
         7 . The supply system of  claim 1 , wherein:
 the control opening comprises a throttle.   
     
     
         8 . The supply system of  claim 1 , wherein:
 the control line is surrounded in the area of the control opening by a shielding element.   
     
     
         9 . The supply system of  claim 8 , wherein:
 the shielding element is a cylindrical shielding tube.   
     
     
         10 . The supply system of  claim 9 , wherein:
 a fluid-permeable grating is mounted in a lower end of the cylindrical tube.   
     
     
         11 . The supply system of  claim 9 , wherein:
 the cylindrical shielding tube and the control line cooperate to form an upwardly opening annular gap, the gap communicating the control opening with hydraulic fluid in the working reservoir.   
     
     
         12 . The supply system of  claim 1 , wherein:
 a throttle is arranged in the suction line.   
     
     
         13 . The supply system of  claim 1 , wherein:
 a check valve is arranged in the suction line.   
     
     
         14 . The supply system of  claim 1 , wherein:
 a float valve is arranged in the suction line.   
     
     
         15 . The supply system of  claim 14 , wherein:
 the float valve includes a float which actuates a ball valve to produce a pressure equalization connection between the low-pressure side of the air pump and the working reservoir.   
     
     
         16 . The supply system of  claim 1 , wherein:
 a throttle communicates the control line into a fluid-free area of the working reservoir.   
     
     
         17 . The supply system of  claim 1 , wherein:
 a pressure limitation valve is connected to the control line between a throttle and the air pump, to equalization pressure between the low-pressure side of the air pump and the working reservoir.   
     
     
         18 . The supply system of  claim 1 , wherein:
 a pressure limitation valve and a check valve are connected to the inlet of the air pump.   
     
     
         19 . The supply system of  claims 1 , wherein:
 a pressure limitation valve and a float valve are connected to the inlet of the air pump).   
     
     
         20 . The supply system of  claim 1 , wherein:
 a throttle is arranged in the control line.   
     
     
         21 . The supply system of  claim 1 , wherein:
 a throttle is arranged in the suction line and the control line.