Stator of a gerotor device and a method for manufacturing roller pockets in a stator of a gerotor device

A method for manufacturing roller pockets in a stator of a gerotor device, the method comprising:

• providing a stator having a cavity including a generally cylindrical section defining a central axis and a plurality of roller pockets angularly spaced around a periphery of the cylindrical section, wherein each roller pocket is configured to receive a respective roller, which acts as an internal tooth of the gerotor device, wherein each roller pocket defines a generally cylindrical roller pocket bearing surface;
• grinding a first section of the roller pocket bearing surface of each roller pocket with a grinding wheel rotating about a rotational axis perpendicular to the central axis while a second section of the roller pocket bearing surface is not in contact with the grinding wheel, wherein the first section is located on a first side of a center line of the roller pocket and the second section is located on a second, opposite, side of the center line;
• grinding the second section of the roller pocket bearing surface of each roller pocket with the grinding wheel rotating about a rotational axis perpendicular to the central axis while the first section of the roller pocket bearing surface is not in contact with the grinding wheel;
• and
• forming a circumferential groove in the bearing surface while grinding the first section.

A method for manufacturing roller pockets in a stator of a gerotor device, the method comprising:

• providing a stator having a cavity including a generally cylindrical section defining a central axis and a plurality of roller pockets angularly spaced around a periphery of the cylindrical section, wherein each roller pocket is configured to receive a respective roller, which acts as an internal tooth of the gerotor device, wherein each roller pocket defines a generally cylindrical roller pocket bearing surface;
• grinding a first section of the roller pocket bearing surface of each roller pocket with a grinding wheel rotating about a rotational axis perpendicular to the central axis while a second section of the roller pocket bearing surface is not in contact with the grinding wheel, wherein the first section is located on a first side of a center line of the roller pocket and the second section is located on a second, opposite, side of the center line;
• and
• grinding the second section of the roller pocket bearing surface of each roller pocket with the grinding wheel rotating about a rotational axis perpendicular to the central axis while the first section of the roller pocket bearing surface is not in contact with the grinding wheel,
• wherein grinding a first section of the roller pocket bearing surface of each roller pocket with a grinding wheel includes grinding the first section of the roller pocket bearing surface of each roller pocket with a contact surface of the grinding wheel, which in a cross section taken normal to a central axis of the stator, follows a radius r1 about a first point, and
• wherein grinding a second section of the roller pocket bearing surface of each roller pocket with a grinding wheel includes grinding the second section of the roller pocket bearing surface of each roller pocket with the contact surface of the grinding wheel, which in a cross section taken normal to a central axis of the stator, follows a radius r2 about a second point, which is offset from the first point,
• wherein r1 is equal in magnitude to r2.

A stator for gerotor device comprising:

• a plurality of rollers;
• a stator body having a forward face, a rear face, a cavity including a generally cylindrical section defining a central axis and a plurality of roller pockets angularly spaced around a periphery of the cylindrical section, wherein each roller pocket defines a nominal center point,
• wherein each roller pocket receives a respective roller, which acts as an internal tooth of the stator,
• wherein each roller pocket includes a generally cylindrical roller pocket bearing surface, against which the respective roller received in the roller pocket bears,
• wherein each bearing surface extends along an arc that partially surrounds the respective roller received in the roller pocket,
• wherein the arc is greater than 185 degrees,
• wherein each bearing surface includes a first section following a first curve and a second section following a second curve, wherein each curve is substantially circular, wherein the first curve is a substantial mirror image of the second curve with respect to a center line through the respective roller pocket and the respective bearing surface deviates from each curve at or adjacent an area of the respective bearing surface intersected by the center line,
• wherein the first curve follows a first radius and the second curve follows a second radius,
• wherein the first radius and the second radius each emanate from a respective point located offset from the nominal center point, wherein the first radius and the second radius provide an interference layout when the gerotor device is in an unpressurized state.