Partial stroke fluidic pump-motor with high mechanical efficiency

An apparatus configurable as one or both of a partial stroke pump or a partial stroke motor, comprising:

• a piston coupled to a rotating shaft to evacuate a fluid within a cylinder during an upstroke;
• a latching check valve in fluid communication with:
• a low pressure port of the cylinder;
• a low pressure supply line at a low pressure;
• and a latch supply line, wherein the latching check valve comprises:
• a center cavity in fluid communication with the low pressure port;
• a seat between the low pressure supply line and the center cavity;
• a blocking member biased to move towards the seat and to block flow therethrough when the pressure in the cylinder is above the low pressure;
• and
• a latch piston contacting the blocking member to hold the blocking member away from the seat in a bypass state to bypass the blocking member;
• and
• a rotary valve selectively coupling one of the low pressure supply and a pilot pressure supply of the fluid to the latch supply line over different timing angle ranges of the rotating shaft, the pilot pressure supply having a pressure greater than the low pressure, wherein a change from low pressure to pilot pressure or vice versa to the latch supply line maintains the bypass state of the latching check valve, wherein, when operating as the partial stroke pump, the bypass state allows the pressure in the cylinder to fall below a high pressure during part of the upstroke, wherein when operating as the partial stroke motor, the bypass state allows the fluid to be evacuated from the cylinder during the upstroke, and wherein the latch piston is separable from the blocking member when not in the bypass state such that the blocking member and seat act as a conventional check valve when not in the bypass state.

A partial stroke motor, comprising:

• a piston moving within a cylinder, the piston driving a rotating shaft responsive to a fluid at a high pressure flowing into the cylinder during a downstroke, the cylinder comprising a high pressure port and a low pressure port;
• a latching check valve in fluid communication with the low pressure port, the latching check valve comprising:
• a center cavity in fluid communication with the low pressure port;
• a seat between a low pressure supply of the fluid at a low pressure and the center cavity;
• a blocking member biased to move towards the seat and to block flow therethrough when the pressure in the cylinder is above the low pressure;
• an actuator piston that is linearly displaceable within the center cavity to bypass the blocking member from blocking the flow in a bypass state of the latching check valve, the actuator piston driven by a latch supply line;
• a first rotary valve in fluid communication with the latch supply line and comprising a first spool rotatably coupled to the rotating shaft, the first spool selectively coupling one of the low pressure supply and a pilot pressure supply of the fluid to the latch supply line over different timing angle ranges of the rotating shaft, the pilot pressure supply having a pressure greater than the low pressure, a first change of pressure to the latch supply line maintaining the bypass state, the bypass state allowing the fluid to be evacuated from the cylinder during an upstroke of the piston;
• an active valve in fluid communication with the high pressure port, the active valve driven by a second actuator piston fluidly coupled to an active valve supply line;
• and
• a second rotary valve in fluid communication with the active valve supply line and comprising a second spool rotatably coupled to the rotating shaft, the active valve spool selectively coupling one of the low pressure supply and the pilot pressure supply of the fluid to the active valve supply line over different second timing angle ranges of the rotating shaft, a second change in pressure to the active valve supply line causing the active valve to block the fluid at the high pressure from entering the cylinder during part of the downstroke.

An apparatus configurable as one or both of a partial stroke pump or a partial stroke motor, comprising:

• a piston coupled to a rotating shaft to evacuate a fluid within a cylinder during an upstroke;
• a latching check valve in fluid communication with:
• a low pressure port of the cylinder;
• a low pressure supply line at a low pressure;
• and a latch supply line;
• and
• a rotary valve selectively coupling one of the low pressure supply and a pilot pressure supply of the fluid to the latch supply line over different timing angle ranges of the rotating shaft, the pilot pressure supply having a pressure greater than the low pressure, wherein a pressure change between the low pressure and the pilot pressure applied by the rotary valve to the latch supply line during each upstroke of the piston causes the latching check valve to change between a bypass state and a conventional check valve state, wherein the bypass state allows fluid to be evacuated from the cylinder at a low pressure during a first part of each upstroke and the conventional check valve state allows the fluid in the cylinder to increase to a high pressure during a second part of each upstroke.