Integrated electro-hydraulic unit
An integrated electro-hydraulic unit including an electric machine having a stator and a rotor. The integrated electro-hydraulic unit includes a hydraulic machine having a shaft configured to rotate around a central axis and a cylinder block coupled to the shaft. The cylinder block includes a plurality of bores receiving a plurality of pistons. The cylinder block is configured to rotate about the central axis to generate reciprocating movement of the plurality of pistons within the plurality of bores. The cylinder block and the shaft are coupled for rotation via a joint that accommodates bending of the shaft while maintaining a parallel orientation of the cylinder block with respect to the central axis. The joint is defined by a barrel-shaped portion of the shaft and a corresponding interior receiving portion of the cylinder block.
1 . An integrated electro-hydraulic unit comprising:
an electric machine including a stator and a rotor; and
a hydraulic machine including a shaft configured to rotate around a central axis and a cylinder block coupled to the shaft, the cylinder block having a plurality of bores receiving a plurality of pistons, wherein the cylinder block is configured to rotate about the central axis to generate reciprocating movement of the plurality of pistons within the plurality of bores,
wherein the cylinder block and the shaft are coupled for rotation via a joint that accommodates bending of the shaft while maintaining a parallel orientation of the cylinder block with respect to the central axis, and
wherein the joint is defined by a portion having a crowning shaft geometry of the shaft and a corresponding interior receiving portion of the cylinder block,
wherein the portion having the crowning shaft geometry is formed by rounding about a constant radius centered outside the shaft as viewed transverse to the central axis.
2 . The integrated electro-hydraulic unit of claim 1 , wherein the interior receiving portion is defined by a locally-decreased diameter section of a central aperture of the cylinder block.
3 . The integrated electro-hydraulic unit of claim 2 , wherein the interior receiving portion of the cylinder block is formed by one or more surfaces extending parallel to the central axis.
4 . The integrated electro-hydraulic unit of claim 1 , wherein the joint includes a splined interface.
5 . The integrated electro-hydraulic unit of claim 1 , further comprising a valve plate configured to direct flow into and out of the plurality of bores in the cylinder block, wherein the cylinder block and the valve plate are flat against each other, and wherein the cylinder block is axially biased toward the valve plate via a biasing member.
6 . The integrated electro-hydraulic unit of claim 1 ,
wherein the shaft includes a diameter, and
wherein a ratio of the radius of the portion having the crowning shaft geometry to the diameter of the shaft is in the range of 100:1 to 140:1.
7 . The integrated electro-hydraulic unit of claim 1 , wherein the shaft includes a monolithic construction.
8 . The integrated electro-hydraulic unit of claim 1 , wherein the joint is axially centered on an axial center of the rotor.
9 . An integrated electro-hydraulic unit comprising:
an electric machine including a stator and a rotor; and
a hydraulic machine including a shaft configured to rotate around a central axis and a cylinder block coupled to the shaft, the cylinder block having a plurality of bores receiving a plurality of pistons, wherein a swashplate cooperates with the plurality of pistons to generate reciprocating movement of the plurality of pistons within the plurality of bores upon rotation of the cylinder block,
wherein the cylinder block and the shaft are coupled via a joint that accommodates bending of the shaft while maintaining a parallel orientation of the cylinder block with respect to the central axis,
wherein the plurality of pistons include ball ends movable about the central axis and along the swashplate to define a piston plane parallel to the swashplate,
wherein an axial center point of the joint is located at an intersection of the piston plane and the central axis.
10 . The integrated electro-hydraulic unit of claim 9 , wherein a center point of the joint is axially aligned with an axial center of the rotor.
11 . The integrated electro-hydraulic unit of claim 9 , wherein the joint is defined by a barrel-shaped portion of the shaft and a corresponding interior receiving portion defined by a locally-decreased diameter section of a central aperture of the cylinder block.
12 . The integrated electro-hydraulic unit of claim 11 ,
wherein the barrel-shaped portion is formed by rounding about a constant radius centered outside the shaft as viewed transverse to the central axis, and
wherein the shaft includes a diameter,
wherein a ratio of the radius of the barrel-shaped portion to the diameter of the shaft is in the range of 110:1 to 130:1.
13 . The integrated electro-hydraulic unit of claim 9 , further comprising a valve plate, wherein the cylinder block is axially biased toward the valve plate via a biasing member.
14 . The integrated electro-hydraulic unit of claim 13 ,
further comprising a first abutment feature,
wherein the cylinder block includes a groove,
and wherein the first abutment feature is received within the groove and is biased via the biasing member.
15 . An integrated electro-hydraulic unit comprising:
an electric machine including a stator and a rotor, the rotor including an axial center; and
a hydraulic machine including a shaft configured to rotate around a central axis and a cylinder block coupled to the shaft, the cylinder block having a plurality of pistons within the cylinder block, the cylinder block configured to rotate about the central axis to generate reciprocating movement of each of the plurality of pistons,
wherein the cylinder block and the shaft are coupled via a joint that accommodates bending of the shaft while maintaining a parallel orientation of the cylinder block with respect to the central axis, wherein the joint is defined by a portion having a crowning shaft geometry of the shaft and a corresponding interior receiving portion of the cylinder block,
wherein a center point of the joint is axially aligned with the axial center of the rotor,
wherein the portion having the crowning shaft geometry is formed by rounding about a constant radius centered outside the shaft as viewed transverse to the central axis.
16 . The integrated electro-hydraulic unit of claim 15 , wherein
the interior receiving portion is defined by a locally-decreased diameter section of a central aperture of the cylinder block,
the interior receiving portion of the cylinder block is formed by one or more surfaces extending parallel to the central axis, and
the interior receiving portion of the cylinder block is configured to engage a splined portion of the shaft.
17 . The integrated electro-hydraulic unit of claim 15 , wherein the center point of the joint is axially aligned with an axial center of the stator.
18 . The integrated electro-hydraulic unit of claim 15 , further comprising
a valve plate;
a biasing member; and
a first abutment feature,
wherein the cylinder block includes a groove, wherein the first abutment feature is received within the groove and is biased via the biasing member such that the cylinder block is axially biased toward the valve plate via the biasing member, and wherein the cylinder block and the valve plate are flat against each other.
19 . The integrated electro-hydraulic unit of claim 15 , wherein the shaft includes a monolithic construction including a splined portion.