Regenerative shock absorber
View Patent ↗Regenerative shock absorber. A piston is disposed for reciprocating motion within a cylinder as a vehicle's suspension system deflects. Hydraulic fluid passes through an hydraulic motor to turn its shaft. The hydraulic motor shaft is connected to an electric generator to generate electricity. Flow characteristics of hydraulic circuits are selected to provide suspension system damping for appropriate wheel control.
1. A motor vehicle comprising: a wheel; a suspension system to control vertical motion of the wheel; and a regenerative shock absorber coupled to the suspension system, the regenerative shock absorber comprising
a piston disposed for reciprocating motion within a cylinder in response to vehicle movement, the piston including a piston rod;
hydraulic fluid contained within the cylinder;
a fluid circuit in fluid communication with a first chamber in the cylinder on a first side of the piston, in fluid communication with a hydraulic motor and wherein upon compression of the piston, hydraulic fluid passes through the hydraulic motor thereby turning a shaft thereof,
the fluid circuit in fluid communication with a second chamber in the cylinder on a second side of the piston and in fluid communication with the first chamber, wherein upon extension of the piston, hydraulic fluid passes from the second chamber to the first chamber through the hydraulic motor;
a capacitive reservoir in fluid communication with the fluid circuit, the capacitive reservoir configured to accommodate a volume of the piston rod introduced into the second chamber upon compression of the piston;
for generating electricity upon rotation of the shaft; and a controller configured to modify the resistance across the electric generator to modify the damping characteristics,
wherein a back-emf on the generator resists motion of an armature relative to a stator to control the flow characteristics of the fluid to both recover energy in response to vehicle movement and to provide effective damping of the suspension system for wheel control without a separate conventional shock absorber included in the suspension system.
2. The regenerative shock absorber of claim 1 further including check valves in the fluid circuit to control flow.
3. The regenerative shock absorber of claim 1 further including power electronics circuitry to provide variable damping of the electric generator.
4. The regenerative shock absorber of claim 3 wherein the power electronics includes a time-averaged resistance feedback controller and a voltage-controlled-output converter.
5. A motor vehicle comprising: a wheel; a suspension system to control vertical motion of the wheel; and a regenerative shock absorber coupled to the suspension system, the regenerative shock absorber comprising
a piston disposed for reciprocating motion within a chamber in response to vehicle movement, the piston including a piston rod;
a fluid circuit that fluidly connects a first portion of the chamber on a first side of the piston, a hydraulic motor having a shaft, a capacitive reservoir used to accommodate piston rod volume and a second portion of the chamber on a second side of the piston, wherein upon movement of the piston in a first direction, fluid in the fluid circuit passes from the first portion of the chamber through the hydraulic motor toward the second portion of the chamber, and wherein upon movement of the piston in a second direction opposite the first direction, fluid in the fluid circuit passes from the second portion of the chamber through the hydraulic motor and toward the first portion of the chamber;
an electric generator connected to the hydraulic motor shaft for generating electricity upon rotation of the hydraulic motor shaft caused by passing of fluid in the fluid circuit through the hydraulic motor; and a controller configured to modify the resistance across the electric generator to modify the damping characteristics,
wherein a back-emf on the generator resists motion of an armature relative to a stator to control the flow characteristics of the fluid to both recover energy in response to vehicle movement and to provide effective damping of the suspension system for wheel control without a separate conventional shock absorber included in the suspension system.
6. The regenerative shock absorber of claim 5 , further including check valves in the fluid circuit to control flow.
7. The regenerative shock absorber of claim 5 , further including power electronics circuitry to provide variable damping by the electric generator.
8. The regenerative shock absorber of claim 7 , wherein the power electronics includes a time-averaged resistance feedback controller and a voltage-controlled-output converter.
9. The regenerative shock absorber of claim 5 , wherein the controller is configured to modify the resistance across the electric generator to modify the damping characteristics.
10. The regenerative shock absorber of claim 1 , wherein the controller controls damping of the electric generator by controlling the resistance across the electric generator.
11. The regenerative shock absorber of claim 10 , wherein the controller controls the resistance across the electric generator winding by selectively switching the electric generator between a first resistance element, an open circuit, and an electrical load.
12. The regenerative shock absorber of claim 11 , wherein the controller selectively switches the electric generator between the first resistance element, the open circuit, and the electrical load using pulse width modulation.
13. The regenerative shock absorber of claim 11 , wherein damping of the electric generator is independent of power output to the electrical load.
14. The regenerative shock absorber of claim 11 , wherein the open circuit comprises a second resistance element, the second resistance element having a higher resistance than the first resistance element.
15. The regenerative shock absorber of claim 11 , wherein an electrical connection between the electrical load and the electric generator comprises an output power converter.
16. The regenerative shock absorber of claim 11 , wherein the electrical load comprises a vehicle battery.
17. The regenerative shock absorber of claim 1 , wherein hydraulic fluid passes through the hydraulic motor in substantially only one direction.
18. The regenerative shock absorber of claim 5 , wherein the controller controls damping of the electric generator by controlling the resistance across the electric generator.
19. The regenerative shock absorber of claim 18 , wherein the controller controls the resistance across the electric generator winding by selectively switching the electric generator between a first resistance element, an open circuit, and an electrical load.
20. The regenerative shock absorber of claim 19 , wherein the controller selectively switches the electric generator between the first resistance element, the open circuit, and the electrical load using pulse width modulation.
21. The regenerative shock absorber of claim 19 , wherein damping of the electric generator is independent of power output to the electrical load.
22. The regenerative shock absorber of claim 19 , wherein the open circuit comprises a second resistance element, the second resistance element having a higher resistance than the first resistance element.
23. The regenerative shock absorber of claim 19 , wherein an electrical connection between the electrical load and the electric generator comprises an output power converter.
24. The regenerative shock absorber of claim 19 , wherein the electrical load comprises a vehicle battery.
25. The regenerative shock absorber of claim 5 , wherein hydraulic fluid passes through the hydraulic motor in substantially only one direction.