Hydraulic pump port plate with variable area metering notch

A swashplate-type axial piston pump comprising:

• a swashplate;
• a plurality of pumping chambers, each pumping chamber including:
• a plunger connected to the swashplate via a slipper foot configured to slide along a plunger engagement surface of the swashplate, and
• a pumping chamber barrel in which an associated plunger undergoes reciprocal motion;
• and
• a port plate including:
• a port plate body;
• a port extending through the port plate body, wherein the port is an inlet port or a discharge port;
• a first metering notch comprising a channel in the port plate body, the first metering notch being in fluidic communication via a first area adjustment passage with a first area adjustment valve configured to adjust the effective area of the first metering notch,
• wherein the first metering notch is disposed at a leading edge of the port;
• and
• wherein the first area adjustment valve is fluidly connected via a second area adjustment passage with the leading edge of the port such that oil may flow from the first metering notch, through the first area adjustment valve and through the second area adjustment passage into the port when the first area adjustment valve is in an open position.

A method for operating a swashplate-type axial piston pump, the method comprising:

• rotating a pumping chamber about a central axis of the swashplate-type axial piston pump and towards an inlet port of a port plate;
• adjusting an effective area of an inlet port metering notch by controlling an inlet port metering notch area adjustment valve actuator;
• rotating the pumping chamber across the inlet port metering notch and into fluidic communication with the inlet port;
• and
• rotating the pumping chamber across the inlet port while drawing fluid through the inlet port and into the pumping chamber.