Fluid-working machine and operating method

A method of operating a fluid-working machine having a plurality of working chambers of cyclically changing volume, said working chambers comprising cylinders within which pistons are arranged to reciprocate, a high-pressure fluid manifold and a low-pressure fluid manifold, at least one valve linking each working chamber of said working chambers to each manifold, the method comprising:

• operating the valves of at least one of said working chambers in a partial motoring mode in which only part of the usable volume of the at least one working chamber is used;
• and
• determining a mode of each working chamber of said working chambers on successive cycles of changing working chamber volume so as to vary the time averaged effective flow rate of fluid through the machine according to a demand level;
• and operating the valves of each of said working chambers to select the determined mode in accordance with an operation sequence which, in the successive cycles of changing working chamber volume, intersperses modes including at least (i) idling modes, and (ii) said partial motoring modes, wherein the sequence of modes of operation is based upon the time history of past systems responses to past decisions.

A fluid-working machine comprising:

• a plurality of working chambers of cyclically varying volume, said working chambers comprising cylinders within which pistons are arranged to reciprocate;
• a high-pressure fluid manifold;
• a low-pressure fluid manifold;
• at least one valve linking each working chamber of said working chambers to each manifold;
• and
• a controller having a configuration to operate the valves of at least one of the said working chambers in a partial motoring mode in which only part of the usable volume of the at least one working chamber is used,
• wherein the controller is further configured to:
• vary the time averaged effective flow rate of fluid through the machine according to a demand level, and operate the valves of each of the working chambers to select the determined mode in accordance with an operation sequence which, in the successive cycles of changing working chamber volume, intersperses modes including at least (i) idling modes, (ii) said partial motoring modes, wherein the sequence of modes of operation is based upon a function of the error between the measured and demanded pressure.

A fluid-working machine comprising:

• a plurality of working chambers of cyclically varying volume, said working chambers comprising cylinders within which pistons are arranged to reciprocate;
• a high-pressure fluid manifold;
• a low-pressure fluid manifold;
• at least one valve linking each working chamber of said working chambers to each manifold;
• and
• a controller having a configuration to operate the valves of at least one of the said working chambers in a partial motoring mode in which only part of the usable volume of the at least one working chamber is used,
• wherein the controller is further configured to:
• vary the time averaged effective flow rate of fluid through the machine according to a demand level, and operate the valves of each of the working chambers to select the determined mode in accordance with an operation sequence which, in the successive cycles of changing working chamber volume, intersperses modes including at least (i) idling modes, (ii) said partial motoring modes, wherein the sequence of modes of operation is based upon the time history of past systems responses to past decisions.

A machine comprising:

• a plurality of working chambers of cyclically changing volume;
• a high-pressure fluid manifold;
• a low-pressure fluid manifold;
• at least one valve linking each working chamber to each manifold;
• and a controller having a configuration to:
• determine a mode of each working chamber on successive cycles of changing working chamber volume so as to vary the time averaged effective flow rate of fluid through the machine according to a demand level, and operate the valves of each of the working chambers to select the determined mode in accordance with an operation sequence which, in the successive cycles of changing working chamber volume, intersperses modes including at least (i) idling modes, (ii) partial stroke modes in which only part of the usable volume of the working chamber is used and (iii) full stroke modes in which all of the usable volume of the working chamber is used.

A machine comprising:

• a plurality of working chambers of cyclically changing volume;
• a high-pressure fluid manifold;
• a low-pressure fluid manifold;
• at least one valve linking each working chamber to each manifold;
• and a controller having a configuration to:
• vary the time averaged effective flow rate of fluid through the machine according to a demand level, and operate the valves of each of the working chambers to select the determined mode in accordance with an operation sequence which, in the successive cycles of changing working chamber volume, intersperses modes including at least (i) idling modes, (ii) partial stroke modes in which only part of the usable volume of the working chamber is used and (iii) full stroke modes in which all of the usable volume of the working chamber is used.

A method of operating a fluid-working machine having a plurality of working chambers of cyclically changing volume, a high-pressure fluid manifold and a low-pressure fluid manifold, at least one valve linking each working chamber to each manifold, the method comprising:

• determining a mode of each of the working chambers on successive cycles of changing working chamber volume so as to vary the time averaged effective flow rate of fluid through the fluid-working machine according to a demand level;
• and
• operating the valves of each of the working chambers to select the determined mode in one of (i) an idling mode, (ii) a partial stroke mode in which only part of the usable volume of the working chamber is used, and (iii) a full stroke mode in which all of the usable volume of the working chamber is used,
• wherein the sequence of modes of operation is tailored for one or more of the smoothest flow result, the most seamless change in audible noise, minimal pressure ripple, and optimum actuator motion.