US 12,117,024 B2
Pilot operated blow-off valves for hydraulic actuators
Clive Tucker, Charlestown, MA (US); and Joseph Thomas Belter, Somerville, MA (US)
Assigned to ClearMotion, Inc., Billerica, MA (US)
Appl. No. 16/500,667
Filed by ClearMotion, Inc., Billerica, MA (US)
PCT Filed May 31, 2018, PCT No. PCT/US2018/035314
§ 371(c)(1), (2) Date Oct. 3, 2019,
PCT Pub. No. WO2018/222821, PCT Pub. Date Dec. 6, 2018.
Claims priority of provisional application 62/513,375, filed on May 31, 2017.
Prior Publication US 2020/0049266 A1, Feb. 13, 2020
Int. Cl. F15B 13/02 (2006.01); B60G 17/044 (2006.01); F15B 7/00 (2006.01)
CPC F15B 13/027 (2013.01) [B60G 17/044 (2013.01); F15B 7/006 (2013.01); F15B 2211/20561 (2013.01); F15B 2211/27 (2013.01); F15B 2211/3051 (2013.01); F15B 2211/3058 (2013.01); F15B 2211/50527 (2013.01); F15B 2211/625 (2013.01); F15B 2211/7053 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A hydraulic actuator comprising:
a hydraulic cylinder having an internal volume;
a piston slidably received in the hydraulic cylinder, thereby dividing the internal volume into a compression chamber and an extension chamber;
a pump having a compression-side port and an extension-side port;
a compression-side flow path that hydraulically connects the compression-side port of the pump to the compression chamber, wherein the compression-side flow path includes a first restriction;
an extension-side flow path that hydraulically connects the extension-side port of the pump to the extension chamber;
a first bypass flow path that connects the compression chamber to the extension chamber, wherein the first bypass flow path does not include the pump;
a first check valve disposed along the first bypass flow path arranged to block flow from the extension chamber to the compression chamber but allow flow in an opposite direction when its cracking pressure is exceeded; and
a compression-side pilot flow path in fluid communication with the compression-side port and a downstream side of the first check valve;
wherein the first restriction and the compression-side pilot flow path are sized and arranged such that the cracking pressure of the first check valve, in response to a pressure differential produced by the pump at a first frequency above a threshold frequency, is greater than the cracking pressure of the first check valve in response to a pressure differential between the compression chamber and the extension chamber, at the first frequency, produced by an external input in at least one operating condition of the hydraulic actuator.