EP4650533A1

EP4650533A1 - Hydraulic apparatus and method of controlling a hydraulic apparatus

Info

Publication number: EP4650533A1
Application number: EP24176469.5A
Authority: EP
Inventors: Riccardo MADAU; Matteo Pellegri; Hiromasa Takahashi; Kenji Hiraku; Souichirou EBIHARA
Original assignee: Danfoss Scotland Ltd; Hitachi Construction Machinery Co Ltd
Current assignee: Danfoss Scotland Ltd; Hitachi Construction Machinery Co Ltd
Priority date: 2024-05-16
Filing date: 2024-05-16
Publication date: 2025-11-19
Also published as: WO2025238369A1

Abstract

The present invention relates to a hydraulic apparatus having a controller and a hydraulic circuit which comprises a first fluid path associated with a first actuator and a second fluid path associated with a second actuator. The hydraulic apparatus has a first configuration wherein the first fluid path is not in fluid communication with the second fluid path. The controller is configured to regulate the first fluid pressure in the first fluid path and the second fluid pressure in the second fluid path in response to an operator input. In a pressure regulation mode, the controller is configured to control the first fluid pressure and/or the second fluid pressure of the hydraulic apparatus operating in the first configuration based on flow and/or pressure characteristics of the hydraulic apparatus operating in a second configuration. In the second configuration, the first fluid path is in fluid communication with the second fluid path.

Description

Field of the invention

The present invention relates to hydraulic apparatuses, including but not limited to hydraulic excavators, and methods of using them.

Background to the invention

It is known to provide a hydraulic apparatus (e.g., a hydraulic excavator) having a first actuator (e.g., boom) supplied by a fluid manifold that is in selective fluid communication (i.e., in selective fluidic communication) with another fluid manifold supplying a second actuator (e.g., swing) via merging valves. Typically, pressurised fluid is supplied via fluid inputs of each manifold from respective pumps. Providing fluid manifolds that can be selectively fluidly connected (i.e., selectively fluidically connected) is known to be advantageous - particularly where the demand of one actuator requires fluid from two or more pumps.
The operation of a hydraulic excavator typically involves repetition of specific patterns of movement. More specifically, the boom, swing, and arm rams/motors will be commanded by the operator according to repeated manually commanded synchronised movement patterns, referred to as 'working cycles' (or, duty cycles). Three common duty cycles performed by excavators are 1) dig and dump, 2) trenching, and 3) grading.
The 'dig and dump' duty cycle, involves simultaneous movement of the boom and swing rotation. Thus, there is simultaneous demand from both the boom and swing actuators. In a system having fluidly coupled fluid paths, the boom and swing actuators are pressure-coupled in the sense that the swing speed is dependent on the boom pressure.
Hydraulic apparatuses having separate manifolds (without flow merging) are also known (see WO2021044148A1 ).
It is in this context that the present invention has been devised.

Summary of the invention

In accordance with an aspect of the present invention, there is provided a hydraulic apparatus comprising:

a controller;
a hydraulic machine comprising a first fluid output and a second fluid output;
a first actuator and a second actuator;
a hydraulic circuit comprising a first manifold and a second manifold;
wherein the first manifold comprises a first fluid path that extends between the first fluid output and the first actuator, and the second manifold comprises a second fluid path that extends between the second fluid output and the second actuator;
the hydraulic apparatus having at least a first configuration wherein the first fluid path is not in fluid communication with the second fluid path;
wherein the controller is configured to regulate the first fluid pressure in the first fluid path and the second fluid pressure in the second fluid path in response to an operator input; and
wherein, in a pressure regulation mode, the controller is configured to control the first fluid pressure and/or the second fluid pressure of the hydraulic apparatus operating in the first configuration based on flow and/or pressure characteristics of the hydraulic apparatus operating in a second configuration, wherein in the second configuration the first fluid path is in fluid communication with the second fluid path.

Other known hydraulic apparatuses having separate manifolds (e.g., as described in WO2021044148A1 ) have the potential to provide improved energy efficiency over conventional systems. However, the inventors have realised that (since the response of these systems is affected by the manifold architecture) users need to adjust their previously learned commands to produce the intended system response - thereby overall efficiency is at least initially reduced.
Providing a hydraulic apparatus having a controller configured to control the first fluid pressure and/or the second fluid pressure of the hydraulic apparatus operating in the first configuration based on flow and/or pressure characteristics of the hydraulic apparatus operating in the second configuration as described herein, makes the hydraulic apparatus straightforward and efficient to operate. In particular, the claimed hydraulic system having the first fluid path separate from the second fluid path results in an operator experience which feels more similar to a conventional hydraulic apparatus. Thus, operators can operate the hydraulic apparatus more easily and efficiently and with improved control. In particular, the operator can use the new system with little or no retraining and/or adapting their style of operation, thus also potentially increasing the pool of appropriately trained operators. Additionally, the efficiency advantages associated with providing a system operable in the first configuration are retained.
It may be that the flow and/or pressure characteristics of the hydraulic apparatus in a second configuration include the first fluid pressure in the first fluid path and/or the second fluid pressure in the second fluid path. It may be that the flow and/or pressure characteristics of the hydraulic apparatus in a second configuration include the ratio of the fluid flow supplying the first actuator relative to the fluid flow supplying the second actuator.
The second configuration is representative of the less efficient conventional machines. That is, by emulating the flow-sharing properties of the conventional machines using the controller, the feel of the conventional machine is emulated as experienced by the operator.
It may be that the hydraulic apparatus does not have another configuration (i.e., a second configuration different from the first configuration) where the first fluid path is in fluid communication with the second fluid path. Alternatively, the hydraulic apparatus may have a second configuration where the first fluid path is in fluid communication with the second fluid path.
That is, it may not be possible for the hydraulic apparatus according to the invention to be configured to be operable in this second configuration. Nonetheless, it will be understood that the first fluid pressure and/or the second fluid pressure may be regulated based on the flow and/or pressure characteristics if the hydraulic system was in the second configuration. That is, in the pressure regulation mode, the controller may be configured to control the hydraulic apparatus to regulate the first fluid pressure and/or the second fluid pressure based on what the flow and/or pressure characteristics of the hydraulic system would be if the first fluid path and second fluid path were in fluid communication. In the pressure regulation mode, the controller may be configured to control the hydraulic apparatus to regulate the first fluid pressure and/or the second fluid pressure based on what the fluid pressures would be in the first fluid path and the second fluid path if the first fluid path and second fluid path were in fluid communication.
It may be that the hydraulic apparatus is an excavator. It may be that the first actuator moves the excavator boom, and the second actuator provides the excavator swing function.
It may be that the hydraulic apparatus comprises a prime mover. It may be that the hydraulic machine comprises a rotatable shaft in driven engagement with the prime mover. The hydraulic machine may further comprise a plurality of working chambers having a volume which varies cyclically with rotation of the rotatable shaft.
It may be that the hydraulic machine is a pump. It may be that the hydraulic machine also functions as a motor (i.e., for regeneration of energy from hydraulic fluid received from the first and/or second manifold).
It may be that the first fluid pressure in the first fluid path and/or the second fluid pressure in the second fluid path are controlled using the hydraulic machine. The first fluid pressure in the first fluid path and/or the second fluid pressure may be functions of the first fluid output and a second fluid output from the hydraulic machine, respectively.
It may be that the pressure regulation provided by the controller in the pressure regulation mode is dependent on the operator input. That is, in a pressure regulation mode, the controller may be configured to control the first fluid pressure and/or the second fluid pressure of the hydraulic apparatus operating in the first configuration in response to an operator input. It may be that the controller is configured to enter into the pressure regulation mode in response to an operator input. It may be that the operator input will correspond to a command to simultaneously actuate the first actuator and the second actuator.
It may be that the operator input is received through an interface, for example an electronic or a hydromechanical or an electronic interface. It may be that the operator input is received from an operator input device, for example one or more joysticks, levers, and/or pedals.
It may be that flow to each actuator is controlled by actuator valves. It may be that the controller is configured to control the actuator valves.
It will be understood that, in the first configuration, the first fluid path is not in fluid communication with the second fluid path at least between the portion of the first fluid path that extends between the first fluid output and the first actuator and the portion of the second fluid path that extends between the second fluid output and the second actuator.
It may be that, in the pressure regulation mode, the controller is configured to control the hydraulic apparatus to regulate the first fluid pressure and/or the second fluid pressure to decrease the pressure difference between the first fluid pressure and the second fluid pressure, and optionally the controller is configured to decrease the higher of the first fluid pressure and the second fluid pressure.
Regulating the pressures so that the pressure difference between the first fluid pressure and the second fluid pressure is decreased allows the operator feel of the conventional systems to be emulated. It may be preferable to limit the higher of the first fluid pressure towards the lower of the second fluid pressure to reduce system losses - thereby increasing energy efficiency.
In systems involving a boom actuator and a swing actuator, the pressure of the boom is primarily dictated by the load acting on the boom actuator (rather than the level of flow within the fluid path supplying the boom actuator, or the demand from the swing).
Accordingly, the pressure in the fluid path supplying the swing actuator may be regulated so that the difference between the fluid pressure in the first fluid path and the fluid pressure in the second fluid path is reduced.
It may be that, in the pressure regulation mode, a first target pressure in the first fluid path is set to be the same as a second target pressure in the second fluid path.
In a conventional system the fluid connection between the first fluid path and the second fluid path (e.g., via a merging valve) means that the merged flow acts as a common pressure source. It may be that a first target pressure is set to be the same as a second target pressure - thereby emulating the common pressure source associated with the merged flow of the conventional system. It may be that the target pressure takes into account losses in the system (e.g., losses due to friction in the fluid paths).
It may be that, in the pressure regulation mode, a first target pressure in the first fluid path and a second target pressure in the second fluid path are variable in response to a change in demand for hydraulic fluid from the first actuator and/or the second actuator. Optionally, the first target pressure is set to be the same as the second target pressure over the pressure variation of the first target pressure and the second target pressure.
By providing a controller where the first target pressure and a second target pressure are variable in response to a change in demand from at least one of the actuators, the feel of a conventional system can be emulated whilst meeting the demanded actuator displacements.
It may be that the first actuator and the second actuator are simultaneously actuatable, and in the pressure regulation mode, the controller is configured to control the hydraulic apparatus to regulate the first fluid pressure and/or the second fluid pressure in response to a demand for hydraulic fluid determined (using the controller) in respect of the first actuator and a simultaneous demand for hydraulic fluid determined (using the controller) in respect of the second actuator.
It may be that, in the pressure regulation mode, the controller is configured to regulate the ratio of the fluid supplying the first actuator to the fluid supplying the second actuator, and optionally, the controller is configured to regulate the ratio of the fluid supplying the first actuator to the fluid supplying the second actuator based on the ratio of the fluid supplying the first actuator to the fluid supplying the second actuator of the hydraulic apparatus in the second configuration.
The inventors have further realised that by regulating the ratio of the fluid supplying the first actuator to the fluid supplying the second actuator the feel of the hydraulic machine is closer to that of the conventional machines, with corresponding advantages. The controller may be configured to regulate the ratio of the fluid supplying the first actuator to the fluid supplying the second actuator based on how the hydraulic fluid from the hydraulic pump would be shared between the first actuator and the second actuator if the first fluid path and second fluid path were in fluid communication.
It may be that one or more working chambers are switchable between being part of the first group and connected to the first manifold, and being part of the second group and connected to the second manifold, optionally by one or more ganging valves. The controller may be configured to switch one or more working chambers from being connected to the first manifold to being connected to the second manifold to regulate the ratio of fluid flow.
It may be that the net displacement of a plurality of groups of one or more of the working chambers is independently variable under the control of the controller. It may be that the controller controls the net displacement of the first and second groups of one or more working chambers to independently vary the rate of flow to or from the first and second manifold respectively, for example to regulate the ratio of fluid flow.
In some embodiments where the controller is configured to regulate the ratio of the fluid supplying the first actuator to the fluid flow supplying the second actuator, it may be that a target ratio of the fluid supplying the first actuator to the fluid supplying the second actuator is the same as the ratio of the fluid supplying the first actuator to the fluid flow supplying the second actuator of the hydraulic apparatus in the second configuration.
It may be that the controller is configured to regulate the flow supplying the first actuator to the fluid flow supplying the second actuator based on a target ratio. By setting a target ratio to match the ratio of the fluid supplying the first actuator to the fluid supplying the second actuator of the hydraulic apparatus in the second configuration the controller effectively re-establishes the proportions of flows absorbed by the actuators in a conventional system, thereby improving the ease of operation of the hydraulic apparatus.
It may be that a target ratio is variable in response to a change in demand for hydraulic fluid from the first actuator and/or the second actuator. Further, it may be that the target ratio of the fluid supplying the first actuator to the fluid supplying the second actuator is the same as what the ratio of the fluid supplying the first actuator to the fluid flow supplying the second actuator would be if the first fluid path and second fluid path were in fluid communication over the variation of the target ratio (i.e., if the apparatus was in the second configuration).
It may be that the first actuator is associated with a first component and configured to move the first component from a first component configuration to a second component configuration, and the second actuator is associated with a second component and configured to move the second component from a respective first component configuration to a respective second component configuration; and wherein, in a tuning mode, the controller is configured to control the flow in the first fluid path and/or the flow in the second fluid path of the hydraulic apparatus in the first configuration, in response to an operator input, to coordinate the arrival of the first component at the second component configuration from the first component configuration with the arrival of the second component at the respective second component configuration from the respective first component configuration.
By controlling the flows to coordinate the arrival times of the first component and second component, the desired behaviour of the components can be achieved with minimal operator adjustment, thereby further improving the ease of operation.
It may be that, in the tuning mode, the controller is configured to control the flow in the first fluid path and/or the flow in the second fluid path of the hydraulic apparatus in the first configuration, in response to the operator input, so that the first component arrives at the second component configuration from the first component configuration at the same time as the second actuator arrives at the respective second component configuration from the respective first component configuration (to coordinate the respective arrivals of the first component and the second component).
It may be that the first component has a first configuration and a second configuration corresponding to a first operator input. It may be that the first component has a third configuration and a fourth configuration corresponding to a second operator input. In addition, it may be that the second component has a respective first configuration and a respective second configuration corresponding to the first operator input and a respective third configuration and a respective fourth configuration corresponding to the second operator input.
It may be that the controller is further configured to control the flow in the first fluid path and/or the flow in the second fluid path of the hydraulic apparatus in the first configuration, in response to the second operator input to coordinate the arrival of the first component at the fourth configuration from the third configuration with the arrival of the second component at the respective fourth configuration from the respective third configuration.
It may be that the first configuration of the first component corresponds to the same configuration as the third configuration of the first component. That is, the first operator input and second operator input correspond to the first component being in the same initial configuration. It may be that the first configuration of the second component corresponds to the same configuration as the third configuration of the second component. That is, the first operator input and second operator input correspond to the second component being in the same initial configuration.
By controlling the flows to coordinate the arrival times of the first component and second component for different operator inputs, the desired behaviour of the components can be achieved with minimal user adjustment.
The flows can be controlled as part of a flow regulation procedure, pressure regulation procedure or actuator position regulation procedure.
It may be that the first component is the boom of a hydraulic excavator and the second component is the cab of the hydraulic excavator. It may be that the first actuator is a boom actuator and the second actuator is a swing actuator (e.g., a swing motor).
It may be that the first configuration and the second configuration of the first component correspond to a first height and a second height of the boom, respectively. It may be that the respective first configuration and the respective second configuration of the second component correspond to a first rotational orientation and a second rotational orientation of the swing actuator, respectively.
It may be that the hydraulic machine comprises a first working chamber group fluidly connected to the first fluid output and a second working chamber group fluidly connected to the second outlet, wherein each working chamber group comprises a plurality of working chambers, and wherein the net fluid displacement of each working chamber group is independently variable under the control of the controller. One or more of the plurality of working chambers may be switchable between being connected to the first working chamber group and the second working chamber group under the control of the controller. It may be that the controller is configured to switch at least one of the plurality of working chambers between the first working chamber group and the second working chamber group based on the operator input. It may be that the controller is configured to determine the required net fluid displacement of each working chamber group based on the operator input and/or based on a measured fluid property in the first or second fluid path, and that the controller is configured to control the flow from the first fluid output and the second fluid output based on this determination.
It may be that each working chamber group is connected to one of the first fluid output and second fluid output at a time, and that for some or all of the working chamber groups, the output to which the respective working chamber group is connected is changeable. That is, it may be that some or all of the individual working chamber groups are switchable (typically under the control of the controller) to change which fluid output of the hydraulic machine they are connected to.
It may be that the controller is configured to control the flow from the first and/or second fluid output based on an estimation of the inertia of at least part of the hydraulic apparatus. It may be that the estimation of the inertia of at least part of the hydraulic apparatus is based on the actuator pressures. The controller may be configured to accept the actuator pressures as inputs to a feedback control algorithm. The feedback control algorithm may be a proportional integral feedback control algorithm having a plurality of PI gains. It may be that the PI gains are modifiable based on the pressures at the first actuator and/or the second actuator.
It may be that the controller is configured to control the flow from the first and/or second fluid output based on a measured fluid property in the first and/or second fluid path. It may be that the measured fluid property is the fluid pressure measured in the first fluid path or the second fluid path.
It may be that the measured fluid properties in the first and/or second fluid path are measured at the respective output of the hydraulic machine (e.g., the pump outlets). It may be that the measured fluid properties in the first and/or second fluid path are measured at the respective actuators.
According to another aspect of the invention there is provided a method of controlling a hydraulic apparatus,

the hydraulic apparatus comprising:
a hydraulic machine comprising a first fluid output and a second fluid output;
a first actuator and a second actuator;
a hydraulic circuit comprising a first manifold and a second manifold;
wherein the first manifold comprises a first fluid path that extends between the first fluid output and the first actuator, and the second manifold comprises a second fluid path that extends between the second fluid output and the second actuator;
the hydraulic apparatus having a first configuration wherein the first fluid path is not in fluid communication with the second fluid path;
the method comprising:
- regulating the first fluid pressure in the first fluid path and the second fluid pressure in the second fluid path in response to an operator input; and
- in a pressure regulation mode, controlling the first fluid pressure and/or the second fluid pressure of the hydraulic apparatus in the first configuration based on flow and/or pressure characteristics of the hydraulic apparatus operating in a second configuration, wherein in the second configuration the first fluid path is in fluid communication with the second fluid path.

It may be that the method further comprises (in the pressure regulation mode) controlling the hydraulic apparatus to regulate the first fluid pressure and/or the second fluid pressure to decrease the pressure difference between the first fluid pressure and the second fluid pressure.
It may be that the method further comprises, in the pressure regulation mode, controlling the first fluid pressure and/or the second fluid pressure in response to the operator input, and/or (in the pressure regulation mode) controlling the hydraulic apparatus to regulate the first fluid pressure in the first fluid path and/or the second fluid pressure in the second fluid path based on the first fluid pressure and/or the second fluid pressure of the hydraulic apparatus in the second configuration. It may be that the method comprises setting a first target pressure in the first fluid path to be the same as a second target pressure in the second fluid path.
It may be that the one or more working chambers are switchable between being part of the first group and connected to the first manifold, and being part of the second group and connected to the second manifold, optionally by one or more ganging valves. It may be that the method includes a step of allocating the working chambers between the first group and the second group.
It may be that the net displacement of a plurality of groups of one or more of the working chambers is independently variable under the control of the controller. It may be that the method involves controlling the net displacement of the first and second groups of one or more working chambers to independently vary the rate of flow to or from the first and second manifold respectively to regulate the ratio of fluid flow.
It may be that the method includes a step of allocating the working chambers between the first group and the second group and a step of controlling the net displacement of the first and second groups of one or more working chambers to independently vary the rate of flow to or from the first and second manifold respectively.
It may be that the method further comprises, in the pressure regulation mode, controlling the hydraulic apparatus to regulate the ratio of the fluid supplying the first actuator to that supplying the second actuator. It may be that the method comprises regulating the ratio of the fluid supplying the first actuator to that supplying the second actuator based on the ratio of the fluid flow supplying the first actuator to that supplying the second actuator of the hydraulic apparatus in the second configuration (i.e., based on how the hydraulic fluid from the hydraulic pump would be shared between the first actuator and the second actuator if the first fluid path and second fluid path were in fluid communication). It may be that the method comprises setting a target ratio of the fluid flow supplying the first actuator to the fluid flow supplying the second actuator to be the same as the ratio of the fluid flow supplying the first actuator to the fluid flow supplying the second actuator of the hydraulic apparatus in the second configuration (i.e., the same as what the ratio of the fluid flow supplying the first actuator to the fluid flow supplying the second actuator would be if the first fluid path and second fluid path were in fluid communication).
It may be that the method further comprises, in the pressure regulation mode, determining the required net fluid displacement from the first fluid outlet and the second fluid outlet based on a measured fluid property in the first or second fluid path and/or the operator input, and optionally wherein the measured fluid property is the fluid pressure in the first fluid path or the second fluid path.
According to another aspect of the invention there is provided a computer program product comprising instructions which, when the program is executed on a computer processing means, causes the computer processing means to carry out any of the above-mentioned methods.
According to another embodiment of the invention there is provided a hydraulic apparatus comprising:

a controller;
a hydraulic machine comprising a first fluid output and a second fluid output;
a first actuator and a second actuator;
a hydraulic circuit comprising a first manifold and a second manifold;
wherein the first manifold comprises a first fluid path that extends between the first fluid output and the first actuator, and the second manifold comprises a second fluid path that extends between the second fluid output and the second actuator;
the hydraulic apparatus having a first configuration wherein the first fluid path is not in fluid communication with the second fluid path;
wherein the controller is configured to regulate the flow in the first fluid path and the flow in the second fluid path in response to an operator input;
wherein the first actuator is associated with a first component and configured to move the first component from a first component configuration to a second component configuration, and the second actuator is associated with a second component and configured to move the second component from a respective first component configuration to a respective second component configuration; and
wherein, in a tuning mode, the controller is configured to control the flow in the first fluid path and/or the flow in the second fluid path of the hydraulic apparatus in the first configuration, in response to an operator input, to coordinate the arrival of the first component at the second component configuration from the first component configuration with the arrival of the second component at the respective second component configuration from the respective first component configuration.

Providing a hydraulic apparatus having a controller configured to control the hydraulic apparatus so that the arrival times of the first and second components are coordinated means that the desired behaviour of the components can be achieved with minimal operator adjustment.
It may be that the first component has a first configuration and a second configuration corresponding to a first operator input. The first component may further have a third configuration and a fourth configuration corresponding to a second operator input. In addition, the second component may have a respective first configuration and a respective second configuration corresponding to the first operator input and a respective third configuration and a respective fourth configuration corresponding to the second operator input.
It may be that the controller is further configured to control the flow in the first fluid path and/or the flow in the second fluid path of the hydraulic apparatus in the first configuration, in response to the second operator input to coordinate the arrival time of the first component at the fourth configuration from the third configuration with the arrival time of the second component at the respective fourth configuration from the respective third configuration.
It may be that the first and third configurations of the first component correspond to one another. That is, the first operator input and second operator input correspond to the first component being in the same initial configuration. It may be that the first configuration of the second component corresponds to the same configuration as the third configuration of the second component. That is, the first operator input and second operator input correspond to the second component being in the same initial configuration.
By controlling the flows so that the arrival times of the first component and the second component are coordinated for different operator inputs the desired behaviour of the components can be achieved with minimal operator adjustment.
It will be understood that the flows can be controlled as part of a flow regulation procedure, pressure regulation procedure or actuator position regulation procedure.
It may be that the first component is the boom of a hydraulic excavator and the second component is the cab of the hydraulic excavator. It may be that the first actuator is a boom actuator and the second actuator is a swing actuator (e.g., a swing motor).
It may be that the first configuration and the second configuration of the first component correspond to a first height and a second height of the boom, respectively. It may be that the respective first configuration and the respective second configuration of the second component correspond to a first orientation and a second orientation of the cab, respectively.
According to another aspect of the invention there is provided a controller for controlling a hydraulic apparatus, the hydraulic apparatus comprising:

a hydraulic machine comprising a first fluid output and a second fluid output;
a first actuator and a second actuator;
a hydraulic circuit comprising a first manifold and a second manifold;
wherein the first manifold comprises a first fluid path that extends between the first fluid output and the first actuator, and the second manifold comprises a second fluid path that extends between the second fluid output and the second actuator;
the hydraulic apparatus having at least a first configuration wherein the first fluid path is not in fluid communication with the second fluid path;
wherein the controller is configured to regulate the first fluid pressure in the first fluid path and the second fluid pressure in the second fluid path in response to an operator input; and
wherein, in a pressure regulation mode, the controller is configured to control the first fluid pressure and/or the second fluid pressure of the hydraulic apparatus operating in the first configuration based on flow and/or pressure characteristics of the hydraulic apparatus operating in a second configuration, wherein in the second configuration the first fluid path is in fluid communication with the second fluid path.

According to another aspect of the invention there is provided a controller for controlling a hydraulic apparatus, the hydraulic apparatus comprising:

a hydraulic machine comprising a first fluid output and a second fluid output;
a first actuator and a second actuator;
a hydraulic circuit comprising a first manifold and a second manifold;
wherein the first manifold comprises a first fluid path that extends between the first fluid output and the first actuator, and the second manifold comprises a second fluid path that extends between the second fluid output and the second actuator;
the hydraulic apparatus having a first configuration wherein the first fluid path is not in fluid communication with the second fluid path;
wherein the controller is configured to regulate the flow in the first fluid path and the flow in the second fluid path in response to an operator input; wherein the first actuator is associated with a first component and configured to move the first component from a first component configuration to a second component configuration, and the second actuator is associated with a second component and configured to move the second component from a respective first component configuration to a respective second component configuration; and
wherein, in a tuning mode, the controller is configured to control the flow in the first fluid path and/or the flow in the second fluid path of the hydraulic apparatus in the first configuration, in response to an operator input, to coordinate the arrival of the first component at the second component configuration from the first component configuration with the arrival of the second component at the respective second component configuration from the respective first component configuration.

Description of the Drawings

An example embodiment of the present invention will now be illustrated with reference to the following Figures in which:

Figure 1A and 1B are schematic diagrams of the fluid circuits of example hydraulic excavators;
Figure 2 shows graphs associated with the operation of a prior art machine;
Figure 3A is a schematic diagram of a hydraulic apparatus according to the invention;
Figure 3B is a schematic diagram of an example hydraulic apparatus;
Figure 4 is a schematic diagram of a hydraulic apparatus according to the invention;
Figure 5 is a schematic diagram of a pump module;
Figure 6 is schematic diagram of a controller; and
Figure 7 is a flow chart, illustrating a method of controlling a hydraulic apparatus according to the invention.

Detailed Description

Figure 1A shows a schematic representation of the fluid circuit of a conventional hydraulic excavator. Figure 1B shows a schematic representation of the fluid circuit of an example hydraulic excavator having two manifolds which are fluidly uncoupled.
Each excavator shown in Figures 1A-1B has a cab 3, a boom 5, a track 7, an arm 9, and a bucket 11. The movement of each of the boom 5, arm 9 and bucket 11 is controlled via a boom actuator 13, arm actuator 15 and bucket actuator 17, respectively. The orientation of the cab 3 is controlled using a swing actuator (i.e., a swing motor/drive) 19. Each hydraulic excavator further comprises a hydraulic machine 21 supplying a first manifold 23 and second manifold 25 via respective fluid outputs. Each manifold extends to a respective group of actuators via valves 27a-f, which divert a controllable amount of fluid to each actuator. Single actuators with two ports are connected to different outputs of the same valve to receive fluid for actuation in opposite directions. Each of the fluid manifolds are connected to a low pressure manifold 28 (e.g., at atmospheric pressure) via respective valve outputs.
In the system shown in Figure 1A, the first manifold 23 and second manifold 25 can be fluidly connected at points 29a-d so that fluid path portions 31 (represented by dashed lines) of each manifold are supplied by both outputs of the hydraulic machine 21. In this example the first manifold 23 can service the bucket 11, the boom 5 and the arm 9. The second manifold 25 can service the arm 9, the boom 5 and the swing actuator 19. In use, the flow from both outputs of the hydraulic machine can merge so that flow is shared between the boom and swing actuators (i.e., by opening valve 27b). Typically, the pressure is set by the boom 5, and the rotation of the cab 3 (i.e., the swing) accelerates at a rate defined by the boom pressure. As the swing accelerates, the swing actuator 19 will absorb more flow (so that less flow is available for supplying the boom actuator 13). Generally, the large rotational inertia of the excavator cab means that the swing accelerates slowly. The demand from the swing impacts the response of the boom (i.e., its speed/acceleration) and vice versa. The relationship between the response of the swing relative to the response of the boom has been termed by the inventors as the lift/rotate ratio. In particular, the lift/rotate ratio is the ratio of the lifting speed of the boom relative to the rotational speed of the cab. The lift/rotate ratio can also be expressed in terms of the flow - i.e., the ratio of the flow supplying the boom actuator relative to the flow supplying the swing actuator.
Figure 1B shows an alternative system, where the first manifold 23 and second manifold 25 are not in fluid connection. In this example the first manifold 23 services only the boom and the bucket, whereas the second manifold 25 services only the swing and the arm. In use, since the swing and boom actuators are no longer pressure-coupled, the response of the swing is no longer dependent on the demand from the boom (or vice versa). This means that the apparatus may not respond to a given operator input how an operator expects (i.e., the response of the boom and swing will no longer respect the lift/rotate ratio associated with an apparatus where the fluid paths supplying the boom and swing are fluidly coupled). This is explained further in relation to Figure 2. Operators are typically more accustomed to operating excavators having a fluid circuit more similar to that shown in Figure 1A compared to Figure 1B.
The plots shown in Figure 2 illustrate how the hydraulic circuit affects the actuator response to an operator command corresponding to the same working cycle. Each graph shows characteristics of a first system (1) where the fluid paths supplying the boom and swing are fluidly connected and a second system (2) where the fluid paths supplying the boom and swing are not fluidly connected. The plots are not intended to represent the actuator responses associated with an apparatus defined according to an embodiment of the invention described herein, rather they illustrate a problem which the invention aims to address.
Plot (a) and plot (d) show a boom pilot pressure and a swing pilot pressure, respectively. These pilot pressures are control signals to respective valves controlling the flow to the respective actuators. That is, the swing pilot pressure is a variable control signal used to control the position of the hydraulically actuated swing control valve and the boom pilot pressure is a variable control signal used to control the position of the hydraulically actuated boom control valve. The operator can control the pilot pressures via an operator input (e.g., using a joystick).
Plots (b) and (e) show the response of the boom and swing over time, respectively. Plots (c) and (f) show the pressure associated with the boom and swing actuators respectively, with plot (f) showing the pressure associated with both directions of swing rotation.
The plots in relation to the second system represent the case where the operator is aiming to realise substantially the same system response (i.e., same boom extension and swing angle with respect to time) from the second system as would be obtained from the first system. As shown in plots (a) and (d), in order to provide the desired response from the second system, the operator needs to provide a modified operator input. As shown in plot (f) this can cause unwanted oscillations in the swing pressure. Further, the manual adaptation of the joystick demand (compared to the demand which the operator is accustomed to providing in relation to the first system) is unfamiliar and inconvenient for the operator. This means that operators used to working with system 1 need to adapt their style of operation to operate system 2, thereby making the second system more difficult for most operators to use.
Figures 3A is a schematic representation of a hydraulic apparatus 100 according to an embodiment of the invention. The hydraulic apparatus 100 includes a controller 102 and a hydraulic machine 103. The hydraulic machine 103 has a first fluid output 105 and a second fluid output 107 for supplying fluid to a first fluid path 109 and second fluid path 111, respectively. As shown in Figure 3, the hydraulic apparatus has a first configuration wherein the first fluid path 109 and second fluid path 111 are not in fluid communication with one another. The hydraulic apparatus further includes a first actuator 113 supplied by the first fluid path 109 and a second actuator 115 supplied by the second fluid path 111.
Figure 3B shows a schematic representation of a second configuration of the hydraulic apparatus. In the second configuration, the first fluid path 109 and the second fluid path 111 are fluidly connected via a merging valve 117. The controller 102 of the hydraulic apparatus shown in Figure 3A is configured to emulate the operator experience of using the apparatus in this second configuration.
In use, in a pressure regulation mode, the controller 102 of the hydraulic apparatus according to Figure 3A controls the first fluid pressure and/or the second fluid pressure of the hydraulic apparatus to decrease the pressure difference between the first fluid path 109 and second fluid path 111. Thereby, the response of the actuators 113 and 115 to an operator input more closely resembles what the response of the actuators would be if the fluid paths were fluidly connected - as shown in Figure 3B.
In this embodiment, the controller 102 is also configured to regulate the ratio of the fluid flow supplying the first actuator 113 relative to the fluid flow supplying the second actuator 115 based on the ratio of the fluid flow supplying the first actuator 113 relative to the fluid flow supplying the second actuator 115 if the fluid paths were in fluid communication as shown in Figure 3B. For example, if the demand from the first actuator was 70% of the total flow from the hydraulic machine and the demand from the second actuator was 30% of the total flow from the hydraulic machine were the fluid paths to be connected, then the controller would control the flow output from the hydraulic machine 103 of the hydraulic apparatus 102 so that 70% of the same total flow was supplied by the first fluid output 105 and 30% of the total flow was supplied by the second fluid output 107 (instead of using a merging valve 117).
Figure 4 is a schematic representation of a hydraulic apparatus 200 according to an embodiment of the invention. The hydraulic apparatus 200 includes a controller 202 and a hydraulic machine 203. The hydraulic apparatus includes a first manifold having a first fluid path 209 and a second manifold having a second fluid path 211. The hydraulic machine comprises a first fluid output 205 and a second fluid output 207 for supplying the first fluid path 209 and second fluid path 211, respectively. Pressure sensors 201 measure the pressure near the first fluid output 205 and the second fluid output 207. The hydraulic apparatus further includes a boom actuator 213 supplied by the first fluid path 209 and a swing actuator 215 supplied by the second fluid path 211. The boom actuator 213 and swing actuator 215 are supplied via a first actuator valve 214 and second actuator valve 216, respectively. The hydraulic machine 203 comprises a plurality of working chamber groups (i.e., pump modules) 204A-H. Each of the working chamber groups 204A-H comprises a number of working chambers in the form of piston cylinder units, PCUs, which are driven through a common rotating shaft 206 in driven engagement with a prime mover 219. Each working chamber group provides an output of hydraulic fluid through a respective high-pressure manifold 208AH to an apportioning block 210, which in turn outputs fluid to the first fluid path 209 and the second fluid path 211. Each of the first and second fluid manifolds are connected to a low-pressure manifold 212.
Figure 4 shows a virtual circuit portion 220 including a virtual valve 217 which is simulated by the controller 202. More specifically, the first fluid path 209 and the second fluid path 211 are fluidly unconnected. However, in use, the controller is configured to set the first fluid pressure in the first fluid path 209 to be the same target pressure as the second fluid pressure in the second fluid path 211 - as if the virtual merging valve 217 was fully open. That is, the controller is configured to simulate the effect of the virtual circuit 220. In this embodiment, the controller 202 is also configured to set the ratio of the fluid flow supplying the first actuator 213 relative to the fluid flow supplying the second actuator 215 to a target ratio. The target ratio is the same as what the ratio of the fluid flow supplying the first actuator 213 to the fluid flow supplying the second actuator 215 would be if the virtual valve 217 of the virtual circuit 220 was fully opened. To provide this flow ratio, the controller 202 can switch which working chamber groups 204A-H are connected to the first fluid output 205 and which are connected to the second fluid output 207. Further, the controller 202 can regulate the net displacement of each individual working chamber group 204A-H. In particular, individual working chambers may be switchable between the working chamber groups 204A-H under the control of the controller.
Further, in a tuning mode, the controller 202 is configured to control the flow in the first and second fluid paths 209 & 211 respectively, in response to an operator input so that the cabin reaches its target orientation (using the swing actuator 215) at the same time as the boom reaches its target height (using the boom actuator 213). That is, the controller 202 controls the lift/rotate ratio to achieve the demanded system response by controlling the share of the flow between the swing and the boom. Considering a first example work cycle, if the system is tuned optimally for 90 degree rotation, then the boom will reach a target height simultaneously with the cab completing its 90 degree rotation. For the same system (without the tuning mode described herein), during a different working cycle involving a 180 degree turn instead of a 90 degree turn, the operator would need to modify their commands (e.g., release the boom joystick during the turn whilst maintaining the swing joystick command) for the boom height and cab rotation targets to be reached simultaneously. In use, in the tuning mode, the controller 202 is configured to divert more flow to the swing actuator 215 so that the rotational acceleration of the cab increases, thereby the boom reaches its target height simultaneously with the completion of the 180 degree turn. The controller 202 is configured to respond to the operator's input identifying the working cycle and control the relative flows to the boom and swing actuators to achieve the desired trajectory for the given work cycle (i.e., tune the lift/rotate ratio). In this embodiment the controller 202 response depends on operator input from joystick commands/pressures. However, it will be understood that in other embodiments measured signals (e.g., pressures) can be monitored during the working cycle to identify the working cycle (without any additional operator input). For example, Al-based/machine-learning methods may be used to estimate the optimal lift/rotate ratio - potentially based on previous operation of the apparatus.
Figure 5 shows an individual pump module which is useful for the present invention. The pump module is a portion of an electronically commutated hydraulic machine (ECM) 400 implementing a pump module. The ECM comprising a plurality of working chambers having cylinders 401 which have working volumes 404 defined by the interior surfaces of the cylinders and pistons 406 which are driven from a rotatable shaft 470 by an eccentric cam 408 and which reciprocate within the cylinders to cyclically vary the working volume of the cylinders. The rotatable shaft is firmly connected to and rotates with a drive shaft. A shaft position and/or speed sensor 410 determines the instantaneous angular position and/or speed of rotation of the shaft and transmits this to the controller 402 through signal line 412, which enables the machine controller to determine the instantaneous phase of the cycles of each cylinder.
The working chambers are each associated with Low Pressure Valves (LPVs) in the form of electronically actuated face-sealing poppet valves 414, which have an associated working chamber and are operable to selectively seal off a channel extending from the working chamber to a low-pressure hydraulic fluid manifold 416, which may connect one or several working chambers, or indeed all of the working chambers in the pump module as is shown here, to the low-pressure hydraulic fluid manifold of the apparatus. The LPVs are normally open solenoid actuated valves which open passively when the pressure within the working chamber is less than or equal to the pressure within the low-pressure hydraulic fluid manifold, i.e. during an intake stroke, to bring the working chamber into fluid communication with the low-pressure hydraulic fluid manifold but are selectively closable under the active control of the controller via LPV control lines 418 to bring the working chamber out of fluid communication with the low-pressure hydraulic fluid manifold. The valves may alternatively be normally closed valves.
The working chambers are each further associated with a respective High-Pressure Valve (HPV) 420 each in the form of a pressure actuated delivery valve. The HPVs open outwards from their respective working chambers and are each operable to seal off a respective channel extending from the working chamber to a high-pressure hydraulic fluid manifold 422, which may connect one or several working chambers, or indeed all as is shown in Figure 5. The HPVs function as normally-closed pressure-opening check valves which open passively when the pressure within the working chamber exceeds the pressure within the high pressure fluid manifold 422. The HPVs also function as normally-closed solenoid actuated check valves which the controller may selectively hold open via HPV control lines 424 once that HPV is opened by pressure within the associated working chamber. Typically, the HPV is not openable by the controller against pressure in the high-pressure hydraulic fluid manifold. The HPV may additionally be openable under the control of the controller when there is pressure in the high-pressure hydraulic fluid manifold but not in the working chamber, or may be partially openable.
In a pumping mode, the controller selects the net rate of displacement of hydraulic fluid from the working chamber to the high-pressure hydraulic fluid manifold by the hydraulic pump by actively closing one or more of the LPVs typically near the point of maximum volume in the associated working chamber's cycle, closing the path to the low-pressure hydraulic fluid manifold and thereby directing hydraulic fluid out through the associated HPV on the subsequent contraction stroke (but does not actively hold open the HPV). The controller selects the number and sequence of LPV closures and HPV openings to produce a flow or create a shaft torque or power to satisfy a selected net rate of displacement. The above 'selection' by the controller is refreshed periodically, or continuously. The selection is refreshed, or updated, when pump modules are moved from being connected to the first manifold to the second manifold, or vice versa.
Some embodiments may include pump modules which are also capable of motoring, thereby regenerating energy from hydraulic fluid received from the hydraulic actuators, and converting it into mechanical energy, for example when an actuator is lowered or when a wheel motor is operated as a pump in order to apply braking torque. In these cases, the working chambers of the pump modules are also adapted to motor in which case the controller actively controls the HPV as well as the LPV and can carry out a motoring mode of operation in which the controller selects the net rate of displacement of hydraulic fluid, displaced by the hydraulic machine, via the high-pressure hydraulic fluid manifold, actively closing one or more of the LPVs shortly before the point of minimum volume in the associated working chamber's cycle, closing the path to the low-pressure hydraulic fluid manifold which causes the hydraulic fluid in the working chamber to be compressed by the remainder of the contraction stroke. The associated HPV opens when the pressure across it equalises and a small amount of hydraulic fluid is directed out through the associated HPV, which is held open by the hydraulic machine controller. The controller then actively holds open the associated HPV, typically until near the maximum volume in the associated working chamber's cycle, admitting hydraulic fluid from the high-pressure hydraulic fluid manifold to the working chamber and applying a torque to the rotatable shaft.
As well as determining whether or not to close or hold open the LPVs on a cycle by cycle basis, the controller is operable to vary the precise phasing of the closure of the HPVs with respect to the varying working chamber volume and thereby to select the net rate of displacement of hydraulic fluid from the high-pressure to the low-pressure hydraulic fluid manifold or vice versa.
Arrows on the manifolds 421, 423 indicate hydraulic fluid flow in the pumping mode; in the motoring mode the flow is reversed.
Typically, in practice, there are a number of pump modules such as that shown in Figure 4, connected by a common shaft and a single controller, and typically using a single shaft position sensor, that can transmit the control signals to the valves associated with each working chamber of each of the pump modules. The working chambers within a pump module need not be evenly spaced around the shaft and are typically interleaved with each other to distribute load along the shaft.
Thus, although the working chambers which make up each pump module are fixed, the pump modules which provide flow to the first and second manifolds can be varied as required.
In some embodiments, in addition to the working chambers, manifolds and actuators which are shown, there will be one or more further pump modules (comprising one or more working chambers) coupled to the common shaft which supply fluid to (or receive fluid from) one or more further actuators through fixed connections. This kind of fixed service is useful for certain types of actuator, e.g. steering actuators.
Figure 6 is a schematic diagram of the controller 702 which could be used in some embodiments. The controller 702 includes a processor circuit 750 in electronic communication with memory 752 which stores a database 754 of pump modules and which working chambers are fixedly associated with which pump modules, a database 756 of which pump modules are currently connected to which manifold, and data 758 concerning parameters of simulated hydraulic fluid circuit (i.e., the second configuration of the apparatus where the fluid paths are in fluid communication). The controller receives pressure and any other relevant measurement signals 760 for each of the first and second hydraulic circuit manifold and also the shaft position and/or speed signal through signal line 762. The feedback signals 760 could be simple pressure signals, however it may also receive actuator position signals, flow measurements, temperature measurements, commands, for example operator commands, displacement demand signals etc. Output from the controller includes working chamber valve control lines 718, 724 - for controlling low pressure valves (LPVs) and, if required, HPVs. Output from the controller also includes valve switching control lines 764 which control valves within the apportioning block.
In an embodiment wherein first actuator is a boom actuator and the second actuator is a swing actuator, the measurement signals 760 comprise a measured boom pressure, a measured swing pressure and relevant pilot pressures arising from operator joystick commands. The pressure levels at the swing and boom actuators are dependent on factors including the arm extension and payload of the bucket. The controller may be configured to accept these pressures as inputs to a pressure feedback algorithm (e.g., a proportional integral control algorithm). The output from the pressure feedback algorithm may be used to modify the swing demand derived from the relevant pilot pressure. As well as allocation of pump module described above, the controller may also be configured to provide additional power and flow management functions - such as pressure drop limiting and anti-droop torque limiting.
In some embodiments, rather than actuator valve commands being communicated independently of the controller, the controller receives commands, e.g. from an electronic interface or operator input peripherals, and controls the actuator valves.
During operation, the controller maintains the database of which pump modules are connected to which manifold, starting from a default configuration. The controller also maintains accumulators (which are internal variables stored in the controller) 766A, 766B of the difference between demanded volume of hydraulic fluid and delivered volume of hydraulic fluid to each manifold by pump modules connected to the respective manifold. As the rotatable shaft turns, decision points are reached at different times (shaft positions) for the various working chambers. At the decision point for a given working chamber, the controller determines which hydraulic circuit module the working chamber is connected to (which requires querying the database 754 of pump modules and which working chambers are fixedly associated with which pump modules, and the database 756 of which pump modules are currently connected to which manifold) and the controller then updates the accumulator of the manifold to which the working chamber is connected depending on the received demand for that manifold. The controller then compares the accumulator value with a threshold and if the accumulated demand exceeds the threshold, it schedules then transmits valve controls signals to cause the working chamber to carry out an active cycle in which the working chamber makes a net displacement of working fluid and subtracts the net displacement of working fluid from the value stored by the accumulator. Otherwise, it causes the working chamber to carry out an inactive cycle in which the working chamber makes no net displacement of working fluid (for example, the controller may transmit a signal to the LPV of the working chamber to hold the LPV open throughout a cycle of working chamber volume) and the accumulator is not modified. In this way, the controller makes decisions for each working chamber as to whether or not to carry out active cycles depending on the demand from the manifold to which the working chamber is connected. The accumulators and demand signals may use any convenient units. In one known example, the demand is expressed as "displacement fraction" which is a fraction of the maximum possible displacement per revolution of the rotating shaft, referred to as F_d. Target flow rate, in volumetric terms, is a product of F_d and the speed of rotation of the rotatable shaft.
From time to time, the controller will determine that there is a requirement to reallocate a pump module from one hydraulic circuit module to another hydraulic circuit module in order to meet changing demand for hydraulic fluid. In this case, the controller transmits a control signal to the relevant valves in the apportioning block to switch the high pressure manifold of the pump module from one manifold to the other and it updates the database 756 of which pump modules are currently connected to which hydraulic circuit modules. Thus, in future, when a decision point is reached for each working chamber of the pump module which has been switched from allocation to one manifold to another manifold, the controller reads the value of the displacement accumulator of the new manifold and thus the demand for hydraulic fluid by the new manifold.
Although the controller is shown here as being implemented by a single processor one skilled in the art will appreciate that the function of the controller may readily be distributed between a plurality of processors and/or circuits.
Figure 7 is a flow chart, illustrating a method 800 of controlling a hydraulic apparatus according to an embodiment of the invention. In the embodiment, the method involves controlling a hydraulic apparatus having a hydraulic machine comprising a first fluid output and a second fluid output, a swing actuator, a boom actuator, and a hydraulic circuit comprising a first manifold and a second manifold. The first manifold comprises a first fluid path that extends between the first fluid output and the boom actuator, and the second manifold comprises a second fluid path that extends between the second fluid output and the swing actuator. The hydraulic apparatus has a first configuration wherein the first fluid path is not in fluid communication with the second fluid path. The method involves, in a pressure regulation mode, controlling the hydraulic apparatus to regulate the first fluid pressure and/or the second fluid pressure based on flow and/or pressure characteristics of the hydraulic apparatus in a second configuration, wherein in the second configuration the first fluid path is in fluid communication with the second fluid path.
The method 800 includes a step of measuring pilot pressures 810 - e.g., pressures arising from operator joystick commands. If the pilot pressures corresponding to each of the boom and swing exceed a predetermined level that indicate a simultaneous demand from the boom and swing actuators, then the following steps will be carried out.
A step of determining the actuator demands 820 involves using the measured pilot pressures to determine the swing demand (i.e., swing flow demand) and the boom demand (i.e., boom flow demand) - e.g., by using displacement look up tables.
The method 800 also a step of measuring pressures that are indicative of the actuator pressures 830. In this embodiment, this step 830 involves measuring a boom pressure and a swing pressure.
In a step to determine a modulated swing demand 840, the measured actuator pressures are used as inputs to a feedback control algorithm such as a proportional integral feedback control algorithm. The actuator pressures are also used as inputs to the feedback control algorithm. Using the output from the proportional integral feedback control algorithm together with the previously determined swing demand, a modulated swing demand is determined.
The method also includes a step of allocating pump modules 850 based on the determined demands. As well as allocation of pump module described above, the controller may also be configured to provide additional power and flow management functions - such as pressure drop limiting and anti-droop torque limiting.
The method further includes a step of outputting the flow commands 860 (e.g., to the pump modules) to control the flow supplying the first manifold and the second manifold.
Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to and do not exclude other components, integers, or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.
Features, integers, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

A hydraulic apparatus comprising:
a controller;

a hydraulic machine comprising a first fluid output and a second fluid output;

a first actuator and a second actuator;

a hydraulic circuit comprising a first manifold and a second manifold;

wherein the first manifold comprises a first fluid path that extends between the first fluid output and the first actuator, and the second manifold comprises a second fluid path that extends between the second fluid output and the second actuator;

the hydraulic apparatus having at least a first configuration wherein the first fluid path is not in fluid communication with the second fluid path;

wherein the controller is configured to regulate the first fluid pressure in the first fluid path and the second fluid pressure in the second fluid path in response to an operator input; and

wherein, in a pressure regulation mode, the controller is configured to control the first fluid pressure and/or the second fluid pressure of the hydraulic apparatus operating in the first configuration based on flow and/or pressure characteristics of the hydraulic apparatus operating in a second configuration, wherein in the second configuration the first fluid path is in fluid communication with the second fluid path.
A hydraulic apparatus according to claim 1,
wherein, in the pressure regulation mode, the controller is configured to control the hydraulic apparatus to regulate the first fluid pressure and/or the second fluid pressure to decrease the pressure difference between the first fluid pressure and the second fluid pressure, and optionally

wherein the controller is configured to decrease the higher of the first fluid pressure and the second fluid pressure.
A hydraulic apparatus according to claim 1 or claim 2,
wherein, in the pressure regulation mode, a first target pressure in the first fluid path is set to be the same as a second target pressure in the second fluid path.
A hydraulic apparatus according to claim 1 or 2,
wherein, in the pressure regulation mode, a first target pressure in the first fluid path and a second target pressure in the second fluid path are variable in response to a change in demand for hydraulic fluid from the first actuator and/or the second actuator, and optionally wherein the first target pressure is set to be the same as the second target pressure over the pressure variation of the first target pressure and the second target pressure.
A hydraulic apparatus according to any preceding claim,
wherein the first actuator and the second actuator are simultaneously actuatable, and

wherein, in the pressure regulation mode, the controller is configured to control the hydraulic apparatus to regulate the first fluid pressure and/or the second fluid pressure in response to a demand for hydraulic fluid from the first actuator and a simultaneous demand for hydraulic fluid from the second actuator.
An apparatus according to any preceding claim,
wherein, in the pressure regulation mode, the controller is configured to regulate the ratio of the fluid supplying the first actuator to the fluid supplying the second actuator, and optionally

wherein the controller is configured to regulate the ratio of the fluid supplying the first actuator to the fluid supplying the second actuator based on the ratio of the fluid supplying the first actuator to the fluid supplying the second actuator of the hydraulic apparatus in the second configuration.
An apparatus according to claim 6, wherein a target ratio of the fluid supplying the first actuator to the fluid supplying the second actuator is the same as the ratio of the fluid supplying the first actuator to the fluid supplying the second actuator of the hydraulic apparatus in the second configuration.
An apparatus according to any preceding claim, wherein the first actuator is associated with a first component and configured to move the first component from a first component configuration to a second component configuration, and the second actuator is associated with a second component and configured to move the second component from a respective first component configuration to a respective second component configuration; and
wherein, in a tuning mode, the controller is configured to control the flow in the first fluid path and/or the flow in the second fluid path of the hydraulic apparatus in the first configuration, in response to an operator input, to coordinate the arrival of the first component at the second component configuration from the first component configuration with the arrival of the second component at the respective second component configuration from the respective first component configuration.
An apparatus according to any preceding claim wherein the hydraulic machine comprises a first working chamber group fluidly connected to the first fluid output and a second working chamber group fluidly connected to the second outlet, wherein each working chamber group comprises a plurality of working chambers, and wherein the net fluid displacement of each working chamber group is independently variable under the control of the controller, and optionally
wherein one or more of the plurality of working chambers are switchable between being connected to the first working chamber group and the second working chamber group under the control of the controller, and optionally

wherein the controller is configured to switch at least one of the plurality of working chambers between the first working chamber group and the second working chamber group based on the operator input, and optionally

wherein the controller is configured to determine the required net fluid displacement of each working chamber group based on the operator input and/or based on a measured fluid property in the first or second fluid path, and the controller is configured to control the flow from the first fluid output and the second fluid output based on this determination.
An apparatus according to any preceding claim, wherein the controller is configured to control the flow from the first and/or second fluid output based on a measured fluid property in the first and/or second fluid path, and optionally wherein the measured fluid property is the fluid pressure measured in the first fluid path or the second fluid path.
A method of controlling a hydraulic apparatus,
the hydraulic apparatus comprising:
a hydraulic machine comprising a first fluid output and a second fluid output;

a first actuator and a second actuator;

a hydraulic circuit comprising a first manifold and a second manifold;

wherein the first manifold comprises a first fluid path that extends between the first fluid output and the first actuator, and the second manifold comprises a second fluid path that extends between the second fluid output and the second actuator;

the hydraulic apparatus having a first configuration wherein the first fluid path is not in fluid communication with the second fluid path;

the method comprising:
regulating the first fluid pressure in the first fluid path and the second fluid pressure in the second fluid path in response to an operator input; and

in a pressure regulation mode, controlling the first fluid pressure and/or the second fluid pressure of the hydraulic apparatus in the first configuration based on flow and/or pressure characteristics of the hydraulic apparatus operating in a second configuration, wherein in the second configuration the first fluid path is in fluid communication with the second fluid path.
A method of controlling a hydraulic apparatus according to claim 11,
the method further comprising,

in the pressure regulation mode, controlling the hydraulic apparatus to regulate the first fluid pressure and/or the second fluid pressure to decrease the pressure difference between the first fluid pressure and the second fluid pressure.
A method of controlling a hydraulic apparatus according to claim 11 or 12,
the method further comprising,

in the pressure regulation mode, controlling the first fluid pressure and/or the second fluid pressure in response to the operator input, and/or

in the pressure regulation mode, controlling the hydraulic apparatus to regulate the first fluid pressure in the first fluid path and/or the second fluid pressure in the second fluid path based on the first fluid pressure and/or the second fluid pressure of the hydraulic apparatus in the second configuration, and optionally

setting a first target pressure in the first fluid path to be the same as a second target pressure in the second fluid path.
A method of controlling a hydraulic apparatus according to any one of claims 11-13,
the method further comprising:
in the pressure regulation mode, determining the required net fluid displacement from the first fluid outlet and the second fluid outlet based on a measured fluid property in the first or second fluid path and/or the operator input, and optionally wherein the measured fluid property is the fluid pressure in the first fluid path or the second fluid path.
A hydraulic apparatus comprising:
a controller;

a hydraulic machine comprising a first fluid output and a second fluid output;

a first actuator and a second actuator;

a hydraulic circuit comprising a first manifold and a second manifold;

wherein the first manifold comprises a first fluid path that extends between the first fluid output and the first actuator, and the second manifold comprises a second fluid path that extends between the second fluid output and the second actuator;

the hydraulic apparatus having a first configuration wherein the first fluid flow path is not in fluid communication with the second fluid path;

wherein the controller is configured to regulate the flow in the first fluid path and the flow in the second fluid path in response to an operator input; wherein the first actuator is associated with a first component and configured to move the first component from a first component configuration to a second component configuration, and the second actuator is associated with a second component and configured to move the second component from a respective first component configuration to a respective second component configuration; and

wherein, in a tuning mode, the controller is configured to control the flow in the first fluid path and/or the flow in the second fluid path of the hydraulic apparatus in the first configuration, in response to an operator input, to coordinate the arrival of the first component at the second component configuration from the first component configuration with the arrival of the second component at the respective second component configuration from the respective first component configuration.