초록 ▼

A hydraulic system having at least one hydraulic valve for actuating a component, wherein a control pressure acting on the hydraulic valve can be activated through a supply pressure of a pilot circuit having at least one actuator. At least one pressure reduction apparatus is connected in series with

A hydraulic system having at least one hydraulic valve for actuating a component, wherein a control pressure acting on the hydraulic valve can be activated through a supply pressure of a pilot circuit having at least one actuator. At least one pressure reduction apparatus is connected in series with the actuator.

대표청구항 ▼

What is claimed is: 1. A hydraulic system having at least one hydraulic valve for actuating a component, said hydraulic system comprising: a pilot circuit having a supply pressure source and including an actuator, wherein the actuator is an electromagnetically operated proportional valve; a pilot o

What is claimed is: 1. A hydraulic system having at least one hydraulic valve for actuating a component, said hydraulic system comprising: a pilot circuit having a supply pressure source and including an actuator, wherein the actuator is an electromagnetically operated proportional valve; a pilot orifice positioned in the pilot circuit between the supply pressure source and the component; wherein the at least one hydraulic valve for actuating the component is responsive to a control pressure that is controllable by the supply pressure of the pilot circuit; and a pressure reduction device connected in series with the pilot orifice, wherein the pressure reduction device is a pressure limiting valve that is connected between the pilot orifice of the pilot circuit and the proportional valve and is operative to reduce a resulting differential pressure between the supply pressure of the pilot circuit and the control pressure, wherein the pressure limiting valve includes a spring-loaded control piston movable relative to a valve seat and having at one end a first area (A1) subjected to the supply pressure and a second area (A2) subjected to the control pressure, and wherein the first and second areas of the control piston are each located at a common end face of the control piston and each of first and second areas faces the proportional valve. 2. A hydraulic system in accordance with claim 1, wherein when the proportional valve is completely open only the first area (A1) of the control piston is subjected to the supply pressure downstream of the pilot orifice, so that a resulting differential pressure in the proportional valve is reduced because of the spring force acting on the control piston. 3. A hydraulic system in accordance with claim 1, wherein when the proportional valve is closing, the second area (A2) of the control piston is first subjected to the control pressure, whereby a pressure upstream of the pressure limiting valve is reduced as a function of the ratio of the first area (A1) to the second area (A2). 4. A hydraulic system in accordance with claim 1, wherein the actuator is an electromagnetically operated on/off valve. 5. A hydraulic system in accordance with claim 4, wherein the spring-loaded control piston of the hydraulic valve is the pressure reduction device. 6. A hydraulic system in accordance with claim 5, wherein the control piston of the hydraulic valve has at least a first area (A3) subjected to the supply pressure downstream of the pilot orifice, and a second area (A4) is subjected to a pressure in the on/off valve in order to provide a desired pressure reduction. 7. A hydraulic system in accordance with claim 6, wherein when the on/off valve is open only the first area (A3) can be subjected to the supply pressure downstream of the pilot orifice, so that a resulting differential pressure in the on/off valve is reduced because of the spring force acting on the control piston. 8. A hydraulic system in accordance with claim 6, wherein when the on/off valve is closing, the second area (A4) of the control piston is first subjected to the resulting pressure in the on/off valve, so that the control piston is movable against the spring force acting on the control piston. 9. A hydraulic system in accordance claim 5, wherein the control piston of the hydraulic valve includes cylindrical sections to apply the control pressure to at least one control conduit. 10. A hydraulic system in accordance with claim 9, wherein a first cylindrical section and a second cylindrical section are provided on the control piston, and a middle section having a reduced outer diameter is positioned between the first cylindrical section and the second cylindrical section. 11. A hydraulic system in accordance with claim 10, wherein transitional areas between the first and second cylindrical sections and the middle section have a rounded shape. 12. A hydraulic system in accordance with claim 1, wherein the first area is an annular area that surrounds the second area at the common end face of the control piston. 13. A hydraulic system in accordance with claim 12, wherein the first area is inclined relative to a control piston longitudinal axis and the second area is substantially perpendicular to the control piston longitudinal axis. 14. A hydraulic system in accordance with claim 1, wherein the valve seat is carried by the proportional valve and includes an opening providing communication between the pilot orifice and a control pressure conduit when the control piston is moved away from the valve seat.