Hydraulic apparatus and operating method

An apparatus comprising:

• a plurality of hydraulic actuators,
• a prime mover,
• a hydraulic machine having a rotatable shaft in driven engagement with the prime mover and comprising at least three working chambers having a volume which varies cyclically with rotation of the rotatable shaft, each working chamber of the hydraulic machine comprising a low-pressure valve which regulates the flow of hydraulic fluid between the working chamber and a low-pressure manifold and a high-pressure valve which regulates the flow of hydraulic fluid between the working chamber and a high-pressure manifold, wherein the working chambers are formed into a plurality of pump modules each of which has a respective high-pressure manifold which is common to the pump module,
• a hydraulic connecting circuit comprising a plurality of inputs, each of which is in fluid communication with the high-pressure manifold of a respective pump module, a plurality of connecting circuit outputs, each of which is in fluid communication with a different one or more of the hydraulic actuators, the hydraulic connecting circuit configured to connect each said connecting circuit input to a said connecting circuit output and comprising a plurality of valves which are switchable to change the connecting circuit output to which a said connecting circuit input is connected, so that each pump module is connected to one connecting circuit output at a time and thereby to the one or more of the hydraulic actuators which are in fluid communication with the respective connecting circuit output,
• a controller configured to actively control at least the low pressure valves of the said working chambers to determine the net displacement of each working chamber on each cycle of working chamber volume, such that the net displacement of the working chambers of each pump module which are connected to a respective connecting circuit output is controlled to meet a respective demand for hydraulic fluid by the one or more actuators in fluid communication with the respective connecting circuit output.

A method of operating an apparatus, the apparatus comprising:

• first and second hydraulic circuit portions, the first hydraulic circuit portion having a first hydraulic circuit portion input, and a plurality of valves configured to regulate the flow of hydraulic fluid from the first hydraulic circuit portion input to each of a first group of at least two hydraulic actuators, the second hydraulic circuit portion having a second hydraulic circuit portion input, and a plurality of valves configured to regulate the flow of hydraulic fluid from the second hydraulic circuit portion input to each of a second group of at least two hydraulic actuators,
• a prime mover,
• a hydraulic machine having a rotatable shaft in driven engagement with the prime mover and comprising at least three working chambers having a volume which varies cyclically with rotation of the rotatable shaft, each working chamber of the hydraulic machine comprising a low-pressure valve which regulates the flow of hydraulic fluid between the working chamber and a low-pressure manifold and a high-pressure valve which regulates the flow of hydraulic fluid between the working chamber and a high-pressure manifold, wherein the working chambers are formed into a plurality of pump modules each pump module comprising a group of one or more of the working chambers and a high-pressure manifold which is common to each working chamber in the group,
• a hydraulic connecting circuit comprising a plurality of connecting circuit inputs, each of which is in fluid communication with the high-pressure manifold of a respective pump module, a first connecting circuit output in fluid communication with the first hydraulic circuit portion and a second connecting circuit output in fluid communication with the second hydraulic circuit portion input, the hydraulic connecting circuit configured to connect each said connecting circuit input to a said connecting circuit output and comprising a plurality of valves which are switchable to change the connecting circuit output to which a said connecting circuit input is connected, so that each pump module is connected to one hydraulic circuit portion at a time and that for some or all of the pump modules, the hydraulic circuit portion to which the respective pump module is connected may be changed,
• the method comprising:
• actively controlling at least the low pressure valves of the said working chambers to determine whether each working chamber undergoes either an active cycle, with a net displacement of working fluid between the low-pressure manifold and the high-pressure manifold of the working chamber, or an inactive cycle, with no net displacement of working fluid between the low-pressure manifold and the high-pressure manifold of the working chamber, and also the said valves, such that the net displacement of the working chambers of each pump module which are connected to the first hydraulic circuit portion is controlled in respond to a first demand for hydraulic fluid of the first hydraulic circuit portion and the net displacement of the working chambers of each pump module which are connected to the second hydraulic circuit portion is controlled in response to an independent second demand for hydraulic fluid of the second hydraulic circuit portion.

A method of operating an apparatus, the apparatus comprising:

• a plurality of hydraulic actuators,
• a prime mover,
• a hydraulic machine having a rotatable shaft in driven engagement with the prime mover and comprising at least three working chambers having a volume which varies cyclically with rotation of the rotatable shaft, each working chamber of the hydraulic machine comprising a low-pressure valve which regulates the flow of hydraulic fluid between the working chamber and a low-pressure manifold and a high-pressure valve which regulates the flow of hydraulic fluid between the working chamber and a high-pressure manifold, wherein the working chambers are formed into a plurality of pump modules each of which has a respective high-pressure manifold which is common to that pump module,
• a hydraulic connecting circuit comprising a plurality of inputs, each of which is in fluid communication with the high-pressure manifold of a respective pump module, a plurality of connecting circuit outputs, each of which is in fluid communication with a different one or more of the hydraulic actuators, the hydraulic connecting circuit configured to connect each said connecting circuit input to a connecting circuit output and comprising a plurality of valves which are switchable to change the connecting circuit output to which a said connecting circuit input is connected, so that each pump module is connected to one connecting circuit output at a time and thereby to the one or more of the hydraulic actuators which are in fluid communication with the respective connecting circuit output,
• the method comprising actively controlling at least the low pressure valves of the said working chambers to determine the net displacement of each working chamber on each cycle of working chamber volume, such that the net displacement of the working chambers of each pump module which are connected to a respective actuator is controlled to meet a respective demand for hydraulic fluid by the one or more actuators in fluid communication with the respective connecting circuit output, and
• changing the connecting circuit output and thereby the one or more hydraulic actuators to which a pump module is connected by switching one or more valves of the hydraulic connecting circuit.