Hydraulic energy recovery system
A machine includes a hydraulic cylinder configured to raise and lower a boom of the machine, and an accumulator selectively fluidly connected to the hydraulic cylinder. The accumulator is configured to receive fluid from the hydraulic cylinder during lowering of the boom. The machine also includes a hydraulic motor fluidly connected to the accumulator via an independent metering valve. The machine further includes a fan driven by the hydraulic motor and configured to assist in cooling fluid displaced from the hydraulic cylinder.
1. A machine, comprising:
a hydraulic cylinder configured to raise and lower a boom of the machine;
an accumulator selectively fluidly connected to the hydraulic cylinder and configured to receive fluid from the hydraulic cylinder during lowering of the boom;
a hydraulic motor fluidly connected to the accumulator via an independent metering valve, wherein the independent metering valve comprises first and second supply valves, and first and second drain valves,
the first supply valve and first drain valve being fluidly connected to a fluid passage extending from the accumulator, and
the second supply valve and the second drain valve being fluidly connected to a fluid passage extending from the hydraulic motor; and
a fan driven by the hydraulic motor and configured to assist in cooling fluid displaced from the hydraulic cylinder.
2. The machine of claim 1 , further including a heat exchanger configured to receive fluid exiting the hydraulic motor, wherein the fan is configured to direct a flow of air across the heat exchanger.
3. The machine of claim 1 , further including a pump fluidly connected to the hydraulic motor and driven by a power source of the machine.
4. The machine of claim 3 , wherein the pump comprises a unidirectional variable displacement pump fluidly connected to the hydraulic motor in an open-loop manner.
5. The machine of claim 4 , wherein the independent metering valve is configured to direct fluid exiting the accumulator to an inlet of the hydraulic motor, and
the pump is configured to direct fluid to the inlet in response to a signal indicative of accumulator pressure.
6. The machine of claim 3 , wherein the pump comprises a bidirectional variable displacement pump fluidly connected to the hydraulic motor and the independent metering valve in a closed-loop manner.
7. The machine of claim 6 , further including a charge pump fluidly connected to the pump, in parallel,
the charge pump configured to provide makeup fluid to the pump.
8. The machine of claim 6 , wherein the independent metering valve is configured to direct fluid exiting the accumulator to an inlet of the pump,
the pump is configured to direct pressurized fluid to the hydraulic motor in order to drive the hydraulic motor, and
fluid exiting the hydraulic motor is directed to the independent metering valve.
9. A machine, comprising:
a hydraulic system including
a first pump driven by a power source of the machine, and
a valve arrangement fluidly connected to the first pump;
a recovery system including
a second pump driven by the power source,
an independent metering valve fluidly connected to the second pump,
an accumulator fluidly connected to the independent metering valve, and
a hydraulic motor fluidly connected to the accumulator via the independent metering valve; and
a hydraulic cylinder configured to raise and lower a boom of the machine, wherein the hydraulic cylinder is selectively fluidly connected to the valve arrangement of the hydraulic system and the accumulator of the recovery system.
10. The machine of claim 9 , further including a first valve regulating flow between the hydraulic cylinder and the valve arrangement, and a second valve regulating flow between the hydraulic cylinder and the accumulator, wherein the second valve is configured to direct fluid from the hydraulic cylinder to the accumulator and the independent metering valve during lowering of the boom.
11. The machine of claim 9 , wherein the hydraulic motor is fluidly connected to the second pump, in a closed-loop manner,
the second pump is configured to direct pressurized fluid to the hydraulic motor in order to drive the hydraulic motor in a first direction, and
fluid exiting the hydraulic motor is directed to the independent metering valve.
12. The machine of claim 11 , wherein the independent metering valve directs fluid received from the hydraulic motor to a heat exchanger of the recovery system, the recovery system further including a fan connected to the hydraulic motor and configured to direct a flow of air across the heat exchanger.
13. The machine of claim 11 , wherein the second pump is configured to direct pressurized fluid to the hydraulic motor via the independent metering valve in order to drive the hydraulic motor in a second direction opposite the first direction.
14. The machine of claim 13 , further including a heat exchanger fluidly connected to the independent metering valve, and a fan connected to the hydraulic motor, wherein
the fan is configured to direct a flow of air across the heat exchanger in a third direction in response to the hydraulic motor being driven, in the first direction, and
to direct a flow of air across the heat exchanger in a fourth direction opposite the third direction in response to the hydraulic motor being driven in the second direction.
15. The machine of claim 9 , wherein the second pump is fluidly connected to the independent metering valve and the hydraulic motor in a closed-loop manner, the recovery system further including a charge pump fluidly connected to the second pump, in parallel, and configured to provide makeup fluid to the second pump.
16. A method of controlling a machine, comprising:
lowering a boom of the machine with a hydraulic cylinder, wherein lowering the boom directs fluid from the hydraulic cylinder to an accumulator;
directing fluid from the accumulator to a pump fluidly connected to the accumulator via an independent metering valve;
directing pressurized fluid from the pump to a hydraulic motor fluidly connected to the independent metering valve; and
directing fluid from the hydraulic motor to a heat exchanger via the independent metering valve.
17. The method of claim 16 , further including cooling the fluid directed to the heat exchanger with a fan connected to the hydraulic motor.
18. The method of claim 16 , further including reversing a flow direction of fluid passing through the hydraulic motor, wherein reversing the flow direction reverses a rotation direction of a fan connected to the hydraulic motor.
19. The method of claim 16 , wherein directing fluid from the accumulator to the pump via the independent metering valve reduces a torque demand of the pump.