Integrated energy generating damper
A linear energy harvesting device that includes a housing and a piston that moves at least partially through the housing when it is compressed or extended from a rest position. When the piston moves, hydraulic fluid is pressurized and drives a hydraulic motor. The hydraulic motor drives an electric generator that produces electricity. Both the motor and generator are central to the device housing. Exemplary configurations are disclosed such as monotube, twin-tube, tri-tube and rotary based designs that each incorporates an integrated energy harvesting apparatus. By varying the electrical characteristics on an internal generator, the kinematic characteristics of the energy harvesting apparatus can be dynamically altered. In another mode, the apparatus can be used as an actuator to create linear movement. Applications include vehicle suspension systems (to act as the primary damper component), railcar bogie dampers, or industrial applications such as machinery dampers and wave energy harvesters, and electro-hydraulic actuators.
1. A suspension system including at least one hydraulic damper assembly comprising:
a damper with a first housing that includes a first volume containing hydraulic fluid at a first pressure and a second volume containing hydraulic fluid at a second pressure, wherein the first volume and the second volume are separated by a piston that is received in the housing and attached to a piston rod, and wherein the first pressure acts on a first side of the piston and the second pressure acts on a second side of the piston;
a second housing that includes a hydraulic unit with a rotational component operatively coupled to an electric machine;
a first flow path between the first volume and the second volume that passes through the hydraulic unit;
a second flow path, between the first volume and the second volume that bypasses the hydraulic unit;
a first valve that controls a first fluid flow through the second flow path;
at least one accumulator; and
a second valve that at least partially controls a second fluid flow from at least one of the first volume and the second volume to the at least one accumulator;
wherein the first housing and the second housing are attached to form a single integrated unit, and wherein the integrated unit and the at least one accumulator form a self-contained hydraulic apparatus.
2. The suspension system of claim 1 , wherein the at least one accumulator includes a first accumulator that is incorporated in the first housing.
3. The suspension system of claim 1 , wherein the hydraulic unit is a hydraulic motor that is driven as a pump in at least one mode of operation.
4. The suspension system of claim 3 , wherein the electric machine is an electric generator that is operated as an electric motor in at least one mode of operation.
5. The suspension system of claim 1 , wherein the piston rod is attached to the second side of the piston and the first volume is a compression volume and the second volume is an extension volume.
6. The suspension system of claim 1 , wherein the piston rod is attached to the first side of the piston and the first volume is an extension volume and the second volume is a compression volume.
7. The suspension system of claim 1 , wherein the electric machine operates in a first direction in a first mode of operation and in a second opposite direction in a second mode of operation.
8. The suspension system of claim 1 , wherein during a first mode of operation the hydraulic unit produces a pressure differential across the piston to actively drive at least one of damper extension and damper retraction, and wherein in a second mode of operation the damper produces a damping force during at least one of damper extension and damper retraction.
9. The suspension system of claim 1 , wherein the first valve is a blow-off valve.
10. The suspension system of claim 9 , wherein the blow-off valve is located in the piston.
11. The suspension system of claim 1 , wherein the at least one accumulator includes a first accumulator and a second accumulator.
12. The suspension system of claim 1 , wherein the electric machine is constructed and arranged to operate at variable speeds in at least one mode of operation.
13. The suspension system of claim 1 , wherein the at least one accumulator has a volume that accommodates fluid displaced from the extension volume by intrusion of the piston rod into the extension volume.
14. The suspension system of claim 1 , wherein at least one of the first valve and the second valve is electrically actuated.
15. A method of operating a hydraulic damper assembly of a suspension system, the method comprising:
operating an electric machine coupled to a hydraulic unit that includes a rotational component, wherein the electric machine and the hydraulic unit are incorporated in a first housing, to produce a differential pressure across a piston slidably received in a damper housing, wherein the damper housing is attached to the first housing;
operating an electric machine coupled to a hydraulic unit to produce a differential pressure across a piston slidably received in a damper housing, wherein the hydraulic unit includes a rotational component, wherein the electric machine and the hydraulic unit are incorporated in a first housing, and wherein the damper housing is attached to the first housing;
exchanging fluid between a compression volume on one side of the piston and the extension volume on a second side of the piston;
flowing a first portion of the exchanged fluid through the hydraulic unit;
controlling flow of a second portion of the exchanged fluid through a flow path that by-passes the hydraulic unit with a first valve;
controlling fluid flow from at least one of the compression volume and extension volume to an accumulator with a second valve.
16. The method of claim 15 , further comprising actively driving the damper with the differential pressure during at least a first mode of operation.
17. The method of claim 16 , further comprising producing a damping force with the differential pressure during at least a second mode of operation.
18. The method of claim 15 , wherein the hydraulic unit is a hydraulic motor that is driven as a pump in at least one mode of operation.
19. The method of claim 18 , wherein the electric machine is an electric generator that is operated as an electric motor in at least one mode of operation.
20. A suspension system including at least one hydraulic damper assembly, comprising:
a damper with a first housing that includes a first volume containing hydraulic fluid at a first pressure and a second volume containing hydraulic fluid at a second pressure, wherein the first volume and the second volume are separated by a piston that is received in the housing and attached to a piston rod, and wherein the first pressure acts on a first side of the piston and the second pressure acts on a second side of the piston;
a second housing that includes a hydraulic unit with a rotational component operatively coupled to an electric machine, wherein the electric machine is constructed and arranged to operate at variable speeds in at least one mode of operation;
at least one accumulator; and
a valve that at least partially controls fluid flow from at least one of the first volume and the second volume to the at least one accumulator;
wherein during a first mode of operation the hydraulic unit produces a pressure differential across the piston to actively drive at least one of damper extension and damper retraction, and wherein in a second mode of operation the damper produces a damping force during at least one of damper extension and damper retraction;
wherein the first housing and the second housing are attached to form a single integrated unit, and wherein the integrated unit and the at least one accumulator form a self-contained hydraulic apparatus.