Active suspension with structural actuator
View Patent ↗An active suspension system is configured in a strut arrangement. The active suspension system comprises a hydraulic actuator and a hydraulic pump/electric motor assembly, wherein the actuator movement is preferably in lockstep with the hydraulic motor-pump and electric motor-generator combination. Torque in the electric motor is instantaneously controlled by a controller to create an immediate force change on the hydraulic actuator. The hydraulic actuator is configured so that it can be used as a strut whereby the actuator has sufficient structural rigidity to carry the applied suspension loads while capable of supplying damper forces in at least three quadrants of the force velocity graph of the suspension actuator operation. Embodiments disclosed include low cost active suspension systems for a MacPherson strut application.
1. A strut actuator for a vehicle suspension, comprising:
a hydraulic motor-pump with a first port and a second port;
an electric motor-generator drivingly connected to said hydraulic motor-pump;
a strut actuator comprising a cylinder divided into a rebound volume and a compression volume by a piston, with an attached piston rod, slidably received in said cylinder wherein said rebound volume is in fluid communication with said first port and said compression volume is in fluid communication with said second port;
a fluid reservoir; and
a flow control system means for fluidly connecting said reservoir to one of said first port and said second port with lower pressure;
wherein said strut actuator is configured to withstand forces applied in a direction that is transverse to the longitudinal axis of said actuator.
2. The apparatus of claim 1 , wherein said flow control system means comprises at least one passive valve.
3. The apparatus of claim 2 , wherein said at least one passive valve is a pilot operated valve.
4. The apparatus of claim 3 , wherein said pilot operated valve is a pilot operated shuttle valve.
5. The apparatus of claim 1 , wherein said flow control system means comprises at least one electronically controlled valve.
6. The apparatus of claim 1 , wherein said fluid reservoir comprises a sealed gas-filled bag.
7. The apparatus of claim 1 , wherein said fluid reservoir comprises a liquid gas interface.
8. The apparatus of claim 1 , wherein said strut actuator is configured to operate in at least three of four quadrants of a force velocity domain of said strut actuator.
9. The apparatus of claim 1 , further comprising an annular conduit at least partially surrounding said cylinder and fluidly interposed between said first port and said rebound volume.
10. The apparatus of claim 1 , further comprising an annular conduit at least partially surrounding said cylinder and fluidly interposed between said second port and said compression volume.
11. The apparatus of claim 1 , wherein said fluid reservoir comprises an annular volume at least partially surrounding said cylinder.
12. The strut actuator of claim 1 wherein the piston rod is a hollow piston rod, and said piston rod comprises a first conduit with a first end in fluid communication with said compression volume and a second end in fluid communication with said first port of said hydraulic motor-pump, and a second conduit with a first end in fluid communication with said rebound volume and a second end in fluid communication with said second port of said hydraulic motor-pump.
13. The strut actuator of claim 1 wherein said first end of said first conduit is in fluid communication with said compression volume through an opening in said piston.
14. The strut actuator of claim 1 wherein said first conduit is substantially cylindrical with a circular cross-section and located along the axis of said piston rod.
15. The strut actuator of claim 1 wherein said second conduit is substantially annular in shape and circumferentially surrounding said first conduit.
16. The strut actuator of claim 1 further comprising a hydraulic motor-pump housing supporting said hydraulic motor-pump, wherein said hydraulic motor-pump housing is fixedly attached to said piston rod.
17. The strut actuator of claim 1 wherein said fluid reservoir is incorporated in said strut actuator.
18. The strut actuator of claim 17 wherein said fluid reservoir is at least partially filled with gas.
19. The strut actuator of claim 18 wherein said gas is selected from the group consisting of nitrogen, argon, and air.
20. The strut actuator of claim 17 wherein said fluid reservoir is separated from said compression volume by a floating piston.
21. The strut actuator of claim 1 further comprising a substantially cylindrical actuator housing forming a substantially cylindrical cavity comprising a substantially open first end, and a second end comprising an attachment surface, wherein said strut actuator is slidably received in said cavity and said second end of said piston rod is axially supported with a radially flexible joint attached to said attachment surface at said second end of said cylindrical actuator housing.
22. The strut actuator of claim 21 wherein said cylindrical actuator housing and strut actuator are part of a strut assembly.
23. The strut actuator of claim 22 wherein said cylindrical actuator housing is configured to be a structural member of said suspension system and to resist a force in a direction transverse to the longitudinal axis of said actuator and a moment with an axis perpendicular to said longitudinal axis.
24. The strut actuator of claim 1 wherein said hydraulic motor-pump is a gerotor hydraulic motor-pump.
25. The strut actuator of claim 24 further comprising a motor generator controller, wherein said strut actuator, said hydraulic motor-pump, said electric motor-generator, and said controller form an integral unit.
26. The strut actuator of claim 25 wherein said integral unit is configured to operate in at least three of four quadrants of a force velocity domain of said strut actuator.
27. The strut actuator of claim 26 further comprising a hydraulic valve configured to limit the operating speed of said hydraulic motor-pump.