Hydraulic control circuit

Abstract

The present invention relates to a hydraulic circuit including: a variable displacement pump, a booster pump, a pump control controlling the displacement of the variable displacement pump, supplied by the booster pump via pressure control means, the pump control including a double-acting cylinder including a first chamber and a second chamber, wherein the first chamber is connected to said booster pump via a first setting line including pressure reducing means, the second chamber is connected to said booster pump via a second setting line including a proportional pressure reducer, such that control of the proportional pressure reducer controls the displacement of the variable displacement pump.

1 . A hydraulic circuit including:
 a variable displacement pump, supplying fluid to said circuit,   a booster pump,   a pump control controlling the displacement of said variable displacement pump, supplied by the booster pump via pressure control means,   
       said circuit being characterized in that said pump control includes a double-acting cylinder comprising a first chamber and a second chamber, wherein
 the first chamber is connected to said booster pump via a first setting line including pressure reducing means, 
 the second chamber is connected to said booster pump via a second setting line including a proportional pressure reducer, 
 
       such that the control of the proportional pressure reducer controls the displacement of the variable displacement pump. 
     
     
         2 . The hydraulic circuit according to the foregoing claim, wherein said pressure reducing means include two restrictions assembled in series, defining an intermediate pressure which supplies said first chamber. 
     
     
         3 . The hydraulic circuit according to  claim 1 , wherein said proportional pressure reducer includes an electrical setting control. 
     
     
         4 . The hydraulic circuit according to  claim 1 , wherein a restriction is placed between the proportional pressure reducer and the second chamber of the cylinder. 
     
     
         5 . The hydraulic circuit according to  claim 4 , wherein the second chamber of the cylinder is connected to the hydraulic pump via a pressure limiter, such that the pressure within said second chamber results from control of the proportional pressure reducer and from the pressure drop created by the flow passing through the pressure limiter through the pressure drop. 
     
     
         6 . The hydraulic circuit according to  claim 5 , wherein said pressure limiter is designed to tap fluid in a high-pressure branch of said circuit and to lead it into the second chamber of the cylinder when the pressure in said high-pressure branch of the circuit is greater than or equal to a defined value. 
     
     
         7 . The hydraulic circuit according to  claim 1 , wherein the variable displacement pump supplies a motor for driving a fan of a cooling circuit. 
     
     
         8 . The hydraulic circuit according to  claim 1 , wherein the variable displacement pump is an axial piston pump, and the variable displacement is controlled by the tilt of a rotating cam plate. 
     
     
         9 . A hydraulic circuit according to  claim 1 , wherein the circuit is equipped with a flow reducer designed to provide a hydraulic fluid leak by tapping hydraulic fluid in a branch of said circuit, the booster pump being configured to inject hydraulic fluid into the circuit in order to compensate for said leak.