Liquid pump with cavitation mitigation

A valve stack for a liquid pump comprising:

• an inlet piece having formed therein each of an inlet valve seat, a fluid inlet, and a plurality of incoming fluid passages extending between the fluid inlet and the inlet valve seat;
• an outlet piece positioned upon a first side of the inlet piece, the outlet piece having formed therein an outlet valve seat, and a fluid outlet;
• a pumping piece positioned upon a second side of the inlet piece, such that the inlet piece is sandwiched between the pumping piece and the outlet piece;
• an inlet check valve positioned at least partially within the inlet piece and movable between a closed position blocking the inlet valve seat, and an open position;
• an outlet check valve positioned at least partially within the outlet piece, and movable between a closed position blocking the outlet valve seat, and an open position;
• the inlet piece, the outlet piece, and the pumping piece defining a common axis, and each of the inlet check valve and the outlet check valve being movable along the common axis between the corresponding closed position and open position;
• the valve stack further forming an inlet chamber between the inlet piece and the pumping piece, an outlet chamber between the inlet piece and the outlet piece, a pumping chamber, and a plurality of flow channels;
• and
• the plurality of flow channels being arranged in a first parallel group extending through the pumping piece between the inlet chamber and the pumping chamber and having a first circumferential distribution about the common axis, and a second parallel group extending through the inlet piece between the inlet chamber and the outlet chamber and having a second circumferential distribution about the common axis.

A liquid pump comprising:

• a pump housing having each of a pump inlet and a pump outlet formed therein;
• an inlet metering valve structured to vary a flow area of the pump inlet;
• a valve assembly within the pump housing and including a valve body having a fluid inlet and a fluid outlet formed therein and a valve stack forming an inlet valve seat and an outlet valve seat;
• an inlet check valve positioned at least partially within the valve stack and movable between a closed position blocking the inlet valve seat, and an open position;
• an outlet check valve positioned at least partially within the valve stack and movable between a closed position blocking the outlet valve seat, and an open position;
• a plunger movable within the valve body between a retracted position and an advanced position;
• the inlet check valve, the outlet check valve, and the plunger defining a common axis that extends through the valve stack, and the inlet check valve being located axially between the outlet check valve and the plunger;
• the valve body further having formed therein a pumping chamber receiving the plunger, an inlet chamber within the valve stack, and an outlet chamber within the valve stack, and each of the pumping chamber, the inlet chamber, and the outlet chamber being centered on the common axis;
• and
• a plurality of flow channels for transitioning a pumped liquid through the valve stack between the fluid inlet and the fluid outlet, and being arranged in a first parallel group extending between the inlet chamber and the pumping chamber and having a first circumferential distribution about the common axis, and a second parallel group extending between the inlet chamber and the outlet chamber and having a second circumferential distribution about the common axis;
• wherein the valve body further includes an outer housing piece, and an insert piece defining a central bore, and the insert piece forming an inlet annulus with the outer housing piece and having a plurality of inlet orifices formed therein and extending between the inlet annulus and the central bore, and wherein the valve stack is within the central bore such that the fluid inlet is in fluid communication with the plurality of inlet orifices;
• and
• wherein the valve stack includes an inlet piece having a plurality of incoming fluid passages extending radially inward from the fluid inlet, an outlet piece, and a pumping piece, and wherein the inlet chamber is defined in part by the inlet piece and in part by the pumping piece, the outlet chamber is defined in part by the inlet piece and in part by the outlet piece, and the pumping chamber is defined in part by the pumping piece and in part by the insert piece.