US 10,890,197 B2
Hydraulic actuator with a frequency dependent relative pressure ratio
Joseph Thomas Belter, Somerville, MA (US); Graham A. Dowie, Jericho, VT (US); Marco Giovanardi, Melrose, MA (US); and Brian Alexander Selden, Concord, MA (US)
Assigned to ClearMotion, Inc., Billerica, MA (US)
Appl. No. 16/484,967
Filed by ClearMotion, Inc., Billerica, MA (US)
PCT Filed Feb. 12, 2018, PCT No. PCT/US2018/017879
§ 371(c)(1), (2) Date Aug. 9, 2019,
PCT Pub. No. WO2018/148689, PCT Pub. Date Aug. 16, 2018.
Claims priority of provisional application 62/457,933, filed on Feb. 12, 2017.
Prior Publication US 2019/0360505 A1, Nov. 28, 2019
Int. Cl. F15B 11/08 (2006.01); B60G 17/04 (2006.01)
CPC F15B 11/08 (2013.01) [B60G 17/0416 (2013.01)] 23 Claims
OG exemplary drawing
 
1. A hydraulic actuator comprising:
a hydraulic cylinder that includes an extension chamber and a compression chamber;
a hydraulic pump, with a first port and a second port, capable of generating a pressure differential between the compression chamber and the extension chamber;
a hydraulic circuit including an extension-side and a compression-side, wherein the extension-side of the circuit includes the extension chamber and a first fluid flow path fluidically connecting the first port to the extension chamber, and wherein the compression-side of the circuit includes the compression chamber and a second fluid flow path fluidically connecting the second port to the compression chamber;
wherein the hydraulic actuator exhibits a first relative compliance factor when exposed to a first oscillating input, and a second relative compliance factor when exposed to a second oscillating input, wherein:
the frequency of the first oscillating input is less than the frequency of the second oscillating input, and
the first relative compliance factor is greater than the second relative compliance factor.
 
20. A method of operating a hydraulic actuator having a hydraulic cylinder with a piston slidably received in the hydraulic cylinder and dividing the hydraulic cylinder into an extension chamber and a compression chamber, the method comprising:
applying a first oscillating input to the actuator, wherein the first oscillating input generates a first pressure wave in the extension chamber and a second pressure wave in the compression chamber, wherein a ratio of an amplitude of the first pressure wave to an amplitude of the second pressure wave is a first relative pressure factor; and
applying a second oscillating input to the actuator, wherein the second oscillating input generates a third pressure wave in the extension chamber and a fourth pressure wave in the compression chamber, wherein a ratio of an amplitude of the third pressure wave to an amplitude of the fourth pressure wave is a second relative pressure factor;
wherein a frequency of the second oscillating input is greater than a frequency of the first oscillating input; and wherein the second relative pressure factor is greater than the first relative pressure factor.