Charged hydraulic system
View Patent ↗In open-circuit hydraulic systems ( 1 ), the cross-sections of the supply lines ( 6 ) and input valves of the hydraulic pump ( 3 ) have to be large, so that sufficient flow flux can be provided. This hinders a reduction of the size of the pump and the whole hydraulic system. It is suggested that the supply flow ( 7 ) of a hydraulic pump ( 3 ) is charged by a second, charging pump ( 2 ), to a mid-pressure level ( 7 ). The cross-sections of the supply flow areas can thus be decreased.
1. A hydraulic system comprising:
a hydraulic high-pressure pump having an output connected to at least one hydraulic consumer;
a hydraulic charging pump having an output hydraulic flow that is connected to an input of the hydraulic high-pressure pump to supply flow thereto;
a supplemental pump; and
a switch adapted to connect and disconnect an output of the supplemental pump to the output of the hydraulic high-pressure pump;
wherein the supplemental pump always charges the hydraulic high-pressure pump through a direct or indirect connection to the input of the hydraulic high-pressure pump, and
wherein the output hydraulic flow of the charging pump is connected to a second hydraulic consumer before connecting to the input of the hydraulic high-pressure pump.
2. The hydraulic system according to claim 1 , wherein the switch switches the supplemental pump between charging the input of the hydraulic high-pressure pump indirectly through the at least one hydraulic consumer and directly at the input.
3. The hydraulic system according to claim 1 , the hydraulic high-pressure pump is a synthetically commutated hydraulic pump.
4. The hydraulic system according to claim 3 , wherein the supplemental pump is a fixed displacement pump.
5. The hydraulic system according to claim 4 , wherein the charging pump is a gear pump.
6. The hydraulic system according to claim 4 , wherein the hydraulic high-pressure pump is adapted to reduce an output flow rate when the supplemental pump is switched from being connected to the input of the hydraulic high-pressure pump to the output of the hydraulic high-pressure pump.
7. The hydraulic system according to claim 1 , wherein the second hydraulic consumer provides a steering function to a vehicle.
8. The hydraulic system according to claim 7 , wherein the at least one hydraulic consumer provides a propel function to the vehicle.
9. A hydraulic system comprising:
a synthetically commutated high-pressure pump having an output connected to at least one hydraulic consumer;
a charging pump having an input from a tank and an output that is connected to an input of the synthetically commutated high-pressure pump to supply flow thereto;
a supplemental pump having an input from the tank and an output connected to a valve that switches between connecting and disconnecting the output of the supplemental pump to the output of the synthetically commutated high-pressure pump;
wherein the supplemental pump always charges the synthetically commutated high-pressure pump through a direct or indirect connection to the input of the synthetically commutated high-pressure pump;
wherein the supplemental pump is a fixed displacement pump;
wherein the valve switches the supplemental pump between charging the input of the synthetically commutated high-pressure pump indirectly through the at least one hydraulic consumer and directly at the input; and
wherein the output hydraulic flow of the charging pump is connected to a second hydraulic consumer before connecting to the input of the synthetically commutated high-pressure pump.
10. The hydraulic system according to claim 9 , wherein the synthetically commutated high-pressure pump is adapted to reduce an output flow rate when the supplemental pump is switched from being connected to the input of the synthetically commutated high-pressure pump to the output of the synthetically commutated high-pressure pump.
11. The hydraulic system according to claim 9 , wherein the second hydraulic consumer provides a steering function to a vehicle.
12. The hydraulic system according to claim 11 , wherein the at least one hydraulic consumer provides a propel function to the vehicle.
13. A hydraulic system for a vehicle comprising:
a synthetically commutated high-pressure pump having an output connected to a first hydraulic consumer providing a propel function to the vehicle;
a charging pump having an input from a tank and an output connected in series to a second hydraulic consumer providing a steering function to the vehicle and an input of the synthetically commutated high-pressure pump to supply charged flow thereto;
a supplemental pump having an input from the tank and an output connected to a valve adapted to switch between connecting and disconnecting the output of the supplemental pump to the output of the synthetically commutated high-pressure pump;
wherein the output of the supplemental pump is always connected to the synthetically commutated high-pressure pump through a direct or indirect connection to the input of the synthetically commutated high-pressure pump.