Inline piston pump
An inline piston pump that is efficient, manufacturable, and durable. The angled bearing surface within the pump that it contacts drives the piston and rotates with the cylinder.
1 . An axial piston device comprising:
a housing including a first end portion and a second end portion and including a low-pressure fluid inlet and a high-pressure fluid outlet at the first end portion of the housing;
a cylinder block rotatably positioned within the housing including a first end portion and a second end portion, the first end portion of the cylinder block being in the first end portion of the housing and the second end portion of the cylinder block being in the second end portion of the housing, the cylinder block including a plurality of cylindrical bores that extend from the first end portion to the second end portion of the cylinder block;
a drive shaft including a first end portion that extends inside of the housing and is configured to drive a rotation of the cylinder block within the housing, the drive shaft defining a cylinder block axis of rotation;
a plurality of pistons, each piston including a first end portion and a second end portion, the pistons being positioned within the cylindrical bores such that the pistons can reciprocate within the cylindrical bores axially along longitudinal axes of the pistons, the first end portions of the pistons being positioned in the cylinder block, and the second end portions of the pistons extending out of the second end portion of the cylinder block;
a yoke assembly located in the second end portion of the housing, the yoke assembly including an angled plate supported by a bearing assembly for rotation relative to the housing about a yoke assembly axis that is oriented at an oblique angle relative to the cylinder block axis of rotation, the angled plate defining a recess, the yoke assembly including a bearing plate that mounts in the recess and includes a bearing surface inclined relative to a plane that is perpendicular to the cylinder block axis of rotation, the bearing surface configured to contact the second end portions of the plurality of pistons, the angled plate and the bearing plate being configured to rotate about the yoke assembly axis synchronously with rotation of the cylinder block about the cylinder block axis of rotation;
a retainer configured to engage the second end portions of the plurality of pistons and limit an axial motion of the pistons relative to the bearing surface, wherein the retainer is a plate that mounts to the angled plate and that includes apertures, wherein each of the pistons extends through a corresponding one of the apertures;
the angled plate including raised mounting locations that are raised relative to the bearing surface such that a spacing is defined between the retainer and the bearing surface when the retainer is mounted to the raised mounting locations of the angled plate, the raised mounting locations defining retainer fastening locations spaced about an exterior of the bearing surface; and
bolts for attaching the retainer to the raised mounting locations of the angled plate at the retainer fastening locations.
2 . The axial piston device of claim 1 , wherein the yoke assembly axis intersects with a bearing surface plane that is coincident with the bearing surface at a bearing plate central point, wherein the bearing plate central point is offset from an intersection point between the yoke assembly axis and the cylinder block axis of rotation, wherein the offset is in a direction of the second end portion of the housing along the yoke assembly axis, and wherein the bearing plate central point is offset from the cylinder block axis of rotation.
3 . The axial piston device of claim 1 , wherein the bolts are outwardly offset with respect to the pistons and positioned to not contact the pistons.
4 . The axial piston device of claim 1 , wherein the second end portion of each piston includes a conical head portion that defines an annular retaining collar.
5 . The axial piston device of claim 1 , wherein the axial piston device is a hydraulic pump.
6 . An axial piston device comprising:
a housing including a first end portion and a second end portion and including a low-pressure fluid inlet and a high-pressure fluid outlet at the first end portion of the housing;
a cylinder block rotatably positioned within the housing including a first end portion and a second end portion, the first end portion of the cylinder block being in the first end portion of the housing and the second end portion of the cylinder block being in the second end portion of the housing, the cylinder block including a plurality of cylindrical bores that extend from the first end portion to the second end portion of the cylinder block;
a drive shaft including a first end portion that extends inside of the housing and is configured to drive a rotation of the cylinder block within the housing, the drive shaft defining a cylinder block axis of rotation;
a plurality of pistons, each piston including a first end portion and a second end portion, the pistons being positioned within the cylindrical bores such that the pistons can reciprocate within the cylindrical bores axially along longitudinal axes of the pistons, the first end portions of the pistons being positioned in the cylinder block, and the second end portions of the pistons extending out of the second end portion of the cylinder block;
an angled plate located in the second end portion of the housing, the angled plate defining a recess;
a bearing assembly provided between the angled plate and the second end portion of the housing enabling the angled plate to rotate about an angled plate axis of rotation that is oriented at an oblique angle with respect to the cylinder block axis of rotation;
a bearing plate positioned within the recess of the angled plate, the bearing plate including a bearing surface configured to contact with the second end portions of the plurality of pistons, the angled plate being configured to support the bearing plate such that the bearing surface is oriented at an oblique angle with respect to the cylinder block axis of rotation;
a retainer that mounts to the angled plate, the retainer being configured to engage the second end portions of the plurality of pistons and limit an axial motion of the pistons relative to the bearing plate, wherein the retainer defines a plurality of apertures, and wherein each of the pistons extends through a corresponding one of the apertures;
bolts for attaching the retainer to the angled plate, the bolts having lengths that extend along the angled plate axis of rotation, the bolts being positioned to not contact the pistons; and
wherein the angled plate, the bearing plate, and the retainer are configured to rotate about the angled plate axis of rotation synchronously with rotation of the cylinder block about the cylinder block axis of rotation.
7 . The axial piston device of claim 6 , wherein the bolts clamp the retainer axially against the angled plate.
8 . The axial piston device of claim 6 , further comprising a pin that limits relative rotation between the bearing plate and the angled plate.
9 . The axial piston device of claim 6 , wherein the second end portion of each piston includes a conical shape.
10 . The axial piston device of claim 6 , wherein the second end portion of each piston includes a head having a tapered shape, wherein an annular face of the tapered shape is adapted to contact the bearing surface and defines a convex curved profile along a longitudinal direction of the piston.
11 . The axial piston device of claim 6 , wherein the second end portion of each piston includes an annular collar that engages the retainer.
12 . The axial piston device of claim 6 , wherein the angle of the angled plate is fixed.
13 . The axial piston device of claim 6 , wherein a rotational speed of the drive shaft varies in order to vary a flow rate of the axial piston device.
14 . The axial piston device of claim 6 , wherein an intersection of a projection of the cylinder block axis of rotation and a projection of the angled plate axis of rotation is within planes defined by a top surface of the retainer and a bottom surface of the retainer.
15 . The axial piston device of claim 6 , wherein the angled plate axis of rotation intersects with a bearing surface plane coincident with an exposed face of the bearing plate at a bearing plate central point that is offset from an intersection point between the angled plate axis of rotation and the cylinder block axis of rotation, wherein the offset is in a direction of the second end portion of the housing along the angled plate axis of rotation.
16 . The axial piston device of claim 6 , wherein the angled plate axis of rotation intersects with a bearing surface plane coincident with an exposed face of the bearing plate at a bearing plate central point, wherein the bearing plate central point is offset from the cylinder block axis of rotation.
17 . An axial piston device comprising:
a cylinder block rotatable about a cylinder block axis of rotation, the cylinder block including a plurality of cylinder block bores;
a plurality of pistons, each piston including a first end portion and a second end portion, the pistons being positioned within the cylinder block bores such that the pistons can reciprocate within the cylinder block bores axially along longitudinal axes of the pistons, the first end portions of the pistons being positioned in the cylinder block, and the second end portions of the pistons extending out of the cylinder block;
an angled plate configured to rotate about an angled plate axis of rotation that is oriented at an oblique angle with respect to the cylinder block axis of rotation;
a bearing surface that rotates with the angled plate about the angled plate axis of rotation, the bearing surface being configured to contact with the second end portions of the plurality of pistons, the bearing surface being oriented at an oblique angle with respect to the cylinder block axis of rotation;
a retainer that mounts to the angled plate, the retainer being configured to engage the second end portions of the plurality of pistons and limit an axial motion of the pistons relative to the bearing surface, wherein the retainer defines a plurality of apertures, and wherein each of the pistons extends through a corresponding one of the apertures;
bolts for attaching the retainer to the angled plate, the bolts having lengths that extend along the angled plate axis of rotation, the bolts being spaced from the pistons to prevent contact between the pistons and the bolts fasteners; and
wherein the angled plate, the bearing surface, and the retainer are configured to rotate about the angled plate axis of rotation synchronously with rotation of the cylinder block about the cylinder block axis of rotation, and wherein the bearing surface is defined by a bearing plate that mounts to the angled plate.
18 . The axial piston device of claim 17 , wherein the bolts axially clamp the retainer with respect to the angled plate to establish an axial spacing between a portion of the retainer that defines the apertures and the bearing surface.
19 . The axial piston device of claim 17 , further comprising raised mounting locations of the angled plate that project in an axial orientation relative to the angled plate axis of rotation for setting an axial spacing between an aperture defining portion of the retainer and the bearing surface when the retainer is fastened to the angled plate, and wherein the retainer is axially clamped in place relative to the angled plate.