A hydraulic circuit associated with an internal combustion engine

Abstract

A hydraulic circuit associated with an internal combustion engine comprising a main cooling circuit of the engine provided with a circulation pump for a cooling fluid, and an auxiliary preheating circuit branched from the main circuit; the pump is a rotary volumetric pump dimensioned so as to generate, at least during a warm-up transient of the engine, a flow rate greater than that required for the cooling of the engine; at least one fraction of the flow rate generated by the pump is sent to the auxiliary circuit where it recovers heat from a fluid at higher temperature, such as the exhaust gases and/or the supercharging compressed air of the engine, and gives it to a fluid at lower temperature, such as for example the engine oil or the passenger compartment air.

1 . A hydraulic circuit ( 1 ) associated with an internal combustion engine (M) and comprising a main cooling circuit ( 2 ) of the engine (M) provided with a circulation pump ( 4 ) for a cooling fluid, characterized in that the pump ( 4 ) is a rotary volumetric pump driven by the engine (M) with a fixed transmission ratio and generating, at least during a warm-up transient of the engine (M), a flow rate greater than that required for the cooling of the engine (M) and by comprising an auxiliary circuit ( 3 ) branched from the main circuit and selectively connectable thereto by valve means ( 20 ), said valve means ( 20 ) being configured for sending to said auxiliary circuit ( 3 ), at least during said warm-up transient of the engine (M), at least a fraction of the flow rate of the cooling fluid pumped by the pump ( 4 ), said auxiliary circuit ( 3 ) comprising at least a first heat exchanger ( 21 ) wherein the cooling fluid absorbs thermal energy from a first fluid ( 23 ;  26 ) at a higher temperature, and at least a second heat exchanger ( 22 ) wherein the cooling fluid transfers thermal energy to a second fluid ( 24 ) at lower temperature. 
     
     
         2 . The circuit according to  claim 1 , characterized in that the first fluid ( 23 ) is constituted by engine exhaust gases. 
     
     
         3 . The circuit according to  claim 1 , characterized in that the first fluid ( 26 ) is constituted by engine supercharging compressed air. 
     
     
         4 . The circuit according to  claim 1 , characterized in that the second fluid ( 24 ) is constituted by engine oil. 
     
     
         5 . The circuit according to  claim 1 , characterized in that the second fluid ( 24 ) is constituted by air entered into the passenger compartment. 
     
     
         6 . The circuit according to  claim 1 , characterized in that the rotary volumetric pump ( 4 ) is a vane pump. 
     
     
         7 . The circuit according to  claim 6 , characterized in that the vane pump ( 4 ) has a rotor ( 8 ) provided with an even number of vanes ( 9 ) and that vanes ( 9 ) diametrically opposite to each other are made from a single element ( 15 ) housed in a sliding manner in a diametral seat of the rotor ( 8 ). 
     
     
         8 . The circuit according to  claim 7 , characterized in that the pump ( 4 ) comprises four vanes ( 8 ) obtained, two by two, by respective elements ( 15 ) housed in a sliding manner in a respective diametral slot ( 16 ) of the rotor. 
     
     
         9 . The circuit according to  claim 1 , characterized in that said transmission ratio is a reduction ratio. 
     
     
         10 . A method of controlling a hydraulic circuit ( 1 ) associated with an internal combustion engine (M), characterized in that it comprises, during the step of warming up the engine, the steps of:
 generating a flow rate of cooling fluid by way of a rotary volumetric pump ( 4 ) in excess with respect to the flow rate required for cooling the engine (M);   utilizing at least a fraction of the flow rate pumped by the pump (M) to withdraw heat from a first fluid ( 23 ;  26 ) at a higher temperature and transfer heat to a second fluid ( 24 ) at the lower temperature.   
     
     
         11 . The method according to  claim 10 , characterized in that the first fluid ( 23 ) is constituted by the engine exhaust gases. 
     
     
         12 . The method according to  claim 10 , characterized in that the first fluid ( 26 ) is constituted by engine supercharging compressed air. 
     
     
         13 . The method according to  claim 10 , characterized in that the second fluid ( 24 ) is constituted by the engine oil. 
     
     
         14 . The method according to  claim 10 , characterized in that the second fluid ( 24 ) is constituted by air entered into the passenger compartment.