US 11,946,462 B2
Hydraulic axial piston unit and method for controlling of a hydraulic axial piston unit
Jaromir Tvaruzek, Ames, IA (US); Samuel Hall, Ames, IA (US); Phil Evans, Ames, IA (US); and Dennis Greene, Ames, IA (US)
Assigned to DANFOSS POWER SOLUTIONS, INC., Ames, IA (US)
Filed by Danfoss Power Solutions Inc., Ames, IA (US)
Filed on Dec. 2, 2019, as Appl. No. 16/700,407.
Prior Publication US 2021/0164501 A1, Jun. 3, 2021
Int. Cl. F04B 1/26 (2006.01); F01B 3/00 (2006.01); F04B 1/30 (2020.01); F04B 1/34 (2006.01); F04B 1/20 (2020.01); F04B 49/00 (2006.01); F04B 49/12 (2006.01)
CPC F04B 1/26 (2013.01) [F01B 3/0058 (2013.01); F04B 1/30 (2013.01); F04B 1/34 (2013.01); F04B 1/20 (2013.01); F04B 49/002 (2013.01); F04B 49/12 (2013.01); F15B 2211/41536 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A hydraulic axial piston unit comprising:
a rotational group for driving or being driven by a driving shaft, and
a tiltable displacement element for adjusting the displacement volume of the rotational group,
wherein the rotational group comprises a rotatable cylinder block in which working pistons are mounted reciprocally moveable in cylinder bores for conveying hydraulic fluid from a kidney-shaped inlet port to a kidney-shaped outlet port located on a valve segment of the hydraulic axial piston unit,
said hydraulic axial piston unit further comprising for the adjustment of the displacement volume:
at least two control ports each located on the valve segment between the respective circumferential ends of the kidney-shaped inlet port and the kidney-shaped outlet port, which control ports can be brought sequentially in fluid connection with the cylinder bores when the cylinder block rotates;
at least one hydraulic fluid injector connected fluidly to one control port, for injecting hydraulic fluid with a variably adjustable pressure level via one control port into passing cylinder bores during a time span when the cylinder bores at least partially overlaps with the control port, and
at least one control line connected to the other control port, for draining hydraulic fluid from the passing cylinder bores,
wherein the at least one hydraulic fluid injector is connected fluidly to both control ports via two control lines connected to a hydraulically, electro-mechanically or pneumatically operable two-position switching valve, wherein the switching valve selects in each position one of the two control lines for injecting of hydraulic fluid by means of the injector and the other control line of the two control lines for draining hydraulic fluid from the other control port.