System for improving the energy efficiency in hydraulic systems, piston accumulator and pressure accumulator provided for such a system

Patent metadata

Field	Value
Publication number	US-9631647-B2
Application number	US-201213261904-A
Country	US
Kind code	B2
Filing date	Dec 3, 2012
Priority date	Dec 3, 2011
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

A hydraulic system includes an actuator operating as a consumer of hydraulic energy and as a generator of hydraulic energy in different operating states, and includes a hydraulic accumulator ( 1 ). In an operating state of the actuator ( 49 ), the accumulator can be charged by the actuator for storing energy. In a different operating state, the accumulator can be discharged for delivering energy to the actuator ( 49 ). The hydraulic accumulator is an adjustable hydropneumatic piston accumulator having a plurality of pressure chambers ( 19, 21, 23, 25 ) adjoining effective surfaces ( 11, 13, 15, 17 ) of different sizes on the fluid side of the accumulator piston ( 5 ). An adjusting arrangement ( 51 ) connects a selected pressure chamber ( 19, 21, 23, 25 ) or a plurality of selected pressure chambers ( 19, 21, 23, 25 ) of the piston accumulator ( 1 ) to the actuator ( 49 ) as a function of the pressure level that prevails on the gas side of the piston accumulator ( 1 ) and on the actuator ( 49 ).

First claim

The invention claimed is:

1. A system for improving energy efficiency in hydraulic systems, the system comprising:
an actuator operable in a consumer operating state thereof as a hydraulic energy consumer and in a generating operating state thereof as a hydraulic energy generator;
a discontinuously adjustable hydropneumatic piston accumulator being chargeable in a charging state thereof to store energy from said actuator and being dischargeable in a discharging state thereof to deliver the energy to said actuator, said accumulator including an accumulator housing and an accumulator piston separating a gas side and a fluid side in said accumulator housing and including a plurality of pressure chambers adjacent to effective surfaces of different sizes on said fluid side;
an adjustment arrangement having valves connecting at least a selected one of said pressure chambers or a selected plurality of said pressure chambers to said actuator as a function of the respective pressure levels on said gas side of said piston accumulator and on said actuator;
an accumulator sensor sensing and sending signals representative of pressure levels on said gas side of said accumulator;
an actuator sensor sensing and sending signals representative of said operating states of said actuator; and
a control logic connected to and operating said valves based on said signals from said sensors.

2. A system according to claim 1 wherein
said accumulator piston comprises a stepped piston having partial piston surfaces on said fluid side forming said effective surfaces, said partial piston surfaces being adjacent cylindrical surfaces of said accumulator piston, said accumulator housing having mating surfaces adjacent to said cylindrical surfaces of said accumulator piston, said mating surfaces, said partial piston surfaces and said cylindrical surfaces defining said pressure chambers, said pressure chambers being separate from one another.

3. A system according to claim 2 wherein
said partial piston surfaces comprises steps axially spaced apart from one another.

4. A system according to claim 3 wherein
at least one of said pressure chambers is disposed in an interior of said accumulator piston.

5. A system according to claim 3 wherein
at least two of said pressure chambers are disposed in an interior of said accumulator piston.

6. A system according to claim 2 wherein
said effective surfaces and said mating surfaces comprises annular surfaces concentrically disposed relative to a longitudinal axis of said piston accumulator.

7. A system according to claim 1 wherein
said valves are switching valves selectively connecting said pressure chambers not connected to said actuator to a tank.

8. A system according to claim 1 wherein
said accumulator sensor senses and sends signals of filling pressure on said gas side of said accumulator; and
said actuator sensor senses and sends signals of system pressure at said actuator.

9. A system according to claim 1 wherein
said actuator sensor comprises at least one displacement measurer providing signals representative of strokes of said accumulator piston to said control logic.

10. A system according to claim 1 wherein
said actuator comprises a working cylinder of a hydraulic system for lifting and lowering a load.

11. A system according to claim 1 wherein
said actuator comprises a hydraulic pump unit of a hydraulic hybrid system.

12. A system for improving energy efficiency in hydraulic systems, the system comprising:
an actuator operable in a consumer operating state thereof as a hydraulic energy consumer and in a generating operating state thereof as a hydraulic energy generator;
a discontinuously adjustable hydropneumatic piston accumulator being chargeable in a charging state thereof to store energy from said actuator and being dischargeable in a discharging state thereof to deliver the energy to said actuator, said accumulator including an accumulator housing and an accumulator piston separating a gas side and a fluid side in said accumulator housing and including a plurality of pressure chambers adjacent to effective surfaces of different sizes on said fluid side on said accumulator piston;
an adjustment arrangement connecting at least a selected one of said pressure chambers or a selected plurality of said pressure chambers to said actuator as a function of the respective pressure levels on said gas side of said piston accumulator and on said actuator; and
mating surfaces in said accumulator housing defining said pressure chambers with said effective surfaces on said accumulator piston, said mating surfaces and said effective surfaces being disposed in steps axially spaced from one another, at least one of said pressure chambers being disposed in an interior or said accumulator piston.

13. A system according to claim 12 wherein
at least two of said pressure chambers are disposed in said interior of said accumulator piston.

14. A system according to claim 12 wherein
said effective surfaces and said mating surfaces comprises annular surfaces concentrically disposed relative to a longitudinal axis of said piston accumulator.

15. A system for improving energy efficiency in hydraulic systems, the system comprising:
an actuator operable in a consumer operating state thereof as a hydraulic energy consumer and in a generating operating state thereof as a hydraulic energy generator;
a discontinuously adjustable hydropneumatic piston accumulator being chargeable in a charging state thereof to store energy from said actuator and being dischargeable in a discharging state thereof to deliver the energy to said actuator, said accumulator including an accumulator housing and an accumulator piston separating a gas side and a fluid side in said accumulator housing and including a plurality of pressure chambers adjacent to effective surfaces of different sizes on said fluid side;
an adjustment arrangement connecting at least a selected one of said pressure chambers or a selected plurality of said pressure chambers to said actuator as a function of the respective pressure levels on said gas side of said piston accumulator and on said actuator;
an accumulator sensor sensing and sending signals representative of filling pressure on said gas side of accumulator;
an actuator sensor sensing and sending signals representative of system pressure at said actuator; and
a control logic connected to and operating said adjustment arrangement based on said signals from said sensors.

16. A system for improving energy efficiency in hydraulic systems, the system comprising:
an actuator operable in a consumer operating state thereof as a hydraulic energy consumer and in a generating operating state thereof as a hydraulic energy generator;
a discontinuously adjustable hydropneumatic piston accumulator being chargeable in a charging state thereof to store energy from said actuator and being dischargeable in a discharging state thereof to deliver the energy to said actuator, said accumulator including on an accumulator housing and an accumulator piston separating a gas side and a fluid side in said accumulator housing and including a plurality of pressure chambers adjacent to effective surfaces of different sizes on said fluid side;
an adjustment arrangement connecting at least a selected one of said pressure chambers or a selected plurality of said pressure chambers to said actuator as a function of the respective pressure levels on said gas side of said piston accumulator and on said actuator;
an accumulator sensor sensing and sending signals representative of press

Assignees

• Hydac Fluidtechnik Gmbh

Inventors

• Schulz Frank
• Bruck Peter

Classifications

• F15B2211/6336

  representing a state of the output member, e.g. position, speed or acceleration · CPC title

• F15B21/14 Primary

  Energy-recuperation means · CPC title

• F15B1/024 Primary

  used as a supplementary power source, e.g. to store energy in idle periods to balance pump load · CPC title

• F15B2211/88

  Control measures for saving energy · CPC title

• F15B2211/625

  Accumulators · CPC title