Positive displacement pump including an unloading device
AssigneeDeere & Company
InventorsRobert C. Emmert, Thomas W. Butts
Life of this patent
Estimating the term…
Abstract
A fluid transfer pump that has a housing, a body portion movable within the housing between a first position and a second position, a gear coupled to the housing, a body cavity defined partially between the body portion and the housing, and an aperture defined in the housing that selectively provides a fluid to the body cavity. When the fluid is applied to the body cavity at or above a pilot pressure, the body portion is in the first position adjacent to the gear and when the fluid is applied to the body cavity at a fluid pressure lower than the pilot pressure, the body portion is in the second position and spaced from the gear.
Claims12
A pump assembly, comprising:
- a case partially defining at least one cavity;
- a ring plunger positioned within the case and slidable along a direction relative to the case between a first position and a second position;
- a pump housing coupled to the case and having a gear rotatably positioned therein;
- an inside wall positioned within the case and including a surface disposed substantially perpendicular to the direction, the inside wall including an aperture through which the ring plunger extends, wherein the aperture is sized to prevent a part of the ring plunger from extending through the aperture;
- wherein, when fluid is provided to the at least one cavity at or above a pilot pressure, the ring plunger is positioned in the first position and when fluid is provided to the at least one cavity below the pilot pressure the ring plunger is positioned in the second position;
- further wherein, in the second position the ring plunger is positioned farther from the gear than when the ring plunger is in the first position.
A pump assembly, comprising:
- a case partially defining a plunger cavity;
- a cover coupled to the case on a first end;
- a pump housing coupled to the case on a second end opposite the first end;
- a ring plunger positioned within the case at least partially in the plunger cavity, the ring plunger slidable along a direction therein between a first position and a second position;
- an inside wall positioned within the case and including a first side and a second side each of which are disposed substantially perpendicular to the direction, the inside wall including an aperture through which the ring plunger extends, wherein the aperture is sized to prevent a part of the ring plunger from extending therethrough;
- a bias member coupled to the ring plunger to provide a biasing force on the ring plunger towards the second position, wherein the bias member is located on the first side of the inside wall;
- an aperture fluidly coupling the plunger cavity to a fluid source;
- wherein, when fluid is provided to the plunger cavity at or greater than a pilot pressure, the biasing force provided by the bias member is overcome by the fluid pressure in the plunger cavity to move the ring plunger to the first position;
- further wherein, in the first position the pump housing provides a working pressure and in the second position the pump housing provides a fluid pressure that is less than the working pressure.
Dependencies are inferred from the claim text.