Hydraulic arrangement
A hydraulic arrangement for regulating a lifting mechanism ( 12 ) of an agricultural machine ( 10 ) is described. The hydraulic arrangement ( 16 ) comprises a hydraulic cylinder ( 24 ) having a chamber ( 50 ) capable of being acted upon by pressure, a proportionally adjustable inflow valve ( 22 ) which is connected on the outlet side via an inflow line ( 30 ) to the chamber ( 50 ) and which is connected on the inlet side to a hydraulic pump ( 18, 18 ′), a first outlet line ( 32 ) which makes a connection between the chamber ( 50 ) and a hydraulic tank ( 20 ), adjustment means ( 42, 44 ) for generating an adjustment signal for the hydraulic cylinder ( 24 ), and an electronic control unit ( 40 ).
1. Hydraulic arrangement for regulating a lifting mechanism ( 12 ) of an agricultural machine ( 10 ), with at least one first hydraulic cylinder ( 24 ) having a chamber ( 50 ) capable of being acted upon by pressure, with at least one proportionally adjustable inflow valve ( 22 ) which is connected on the outlet side via a first inflow line ( 30 ) to the chamber ( 50 ) and which is connected on the inlet side to a hydraulic pump ( 18 , 18 ′), with at least one first outflow line ( 32 ) which makes a connection between the chamber ( 50 ) and a hydraulic tank ( 20 ), with adjustment means ( 42 , 44 ) for generating an adjustment signal for the hydraulic cylinder ( 24 ), and with an electronic control unit ( 40 ), characterized in that a first electroproportional pressure relief valve ( 26 ) is arranged in the first outflow line ( 32 ) and a first non-return valve ( 28 ) closing in the direction of the inflow valve ( 22 ) is arranged in the first inflow line ( 30 ), and also one or more sensors ( 36 , 38 ) related to the at least first hydraulic cylinder ( 24 ) and generating a sensor signal are provided, the at least first pressure relief valve ( 26 ) being controllable or regulatable as a function of the one or more sensor signals and/or of the adjustment signal.
2. Hydraulic arrangement according to claim 1 , further comprising at least one second hydraulic cylinder ( 24 ′) parallel to the first hydraulic cylinder ( 24 ), and one or more sensors ( 36 ′, 38 ′) related to the second hydraulic cylinder ( 24 ′) and generating a second sensor signal, and further wherein the adjustment means ( 42 , 44 ) generates a second adjustment signal characterized in that, the at least one second hydraulic cylinder ( 24 ′) has a second chamber ( 50 ′) capable of being acted upon by pressure and which can be activated similarly to the first hydraulic cylinder ( 24 ) via a second proportionally adjustable inflow valve ( 22 ′) and is provided with a second inflow line ( 30 ′) provided with a second non-return valve ( 28 ′) and a second outflow line ( 32 ′) provided with a second electroproportional pressure relief valve ( 26 ′), the second pressure relief valve ( 26 ′) being controllable or regulatable as a function of the second sensor signals and/or of the second adjustment signal.
3. Hydraulic arrangement according to one of claims 1 - 2 , characterized in that the adjustment means ( 42 , 44 ) are designed as an actuating lever, a joystick, or an actuating switch.
4. Hydraulic arrangement according to one of claim 1 , characterized in that at least one sensor ( 36 , 36 ′) is designed as a position sensor which delivers a sensor signal proportional to a position of a hydraulic cylinder piston ( 52 , 52 ′).
5. Hydraulic arrangement according to one of claim 1 , characterized in that at least one sensor ( 38 , 38 ′) is a pressure sensor or load bolt which delivers a sensor signal proportional to a pressure in the chamber ( 50 , 50 ′) of the at least one first hydraulic cylinder ( 24 , 24 ′).
6. Hydraulic arrangement according to one of claim 1 , characterized in that a setting device ( 46 ) is provided, as a potentiometer which is connected to the control unit ( 40 ) and by means of which a manipulated variable for the control unit ( 40 ) can be predetermined.
7. Hydraulic arrangement according to one of claim 1 , characterized in that the inflow valve ( 22 , 22 ′) has on the outlet side a connection to the hydraulic tank ( 20 ), and the hydraulic pump ( 18 ) is designed as a constant-flow pump.
8. Hydraulic arrangement according to one of claim 1 , characterized in that the hydraulic pump ( 18 ′) is designed as a variable-displacement pump system adjustable as a function of a pressure acting in the first and/or second or further inflow line ( 30 , 30 ′).
9. Hydraulic arrangement according to claim 1 , characterized in that further sensors ( 72 ) are provided, as contact sensors which detect with respect to the ground surface a position of an attachment ( 14 ) or mounted implement fastened to the lifting mechanism ( 12 ) of the agricultural machine ( 10 ) and which are connected to the electronic control unit ( 40 ).