Control of hydraulic power units for material testing

Abstract

According to one embodiment of the disclosure, there is provided a method for controlling a hydraulic power unit (HPU) that provides pressurized hydraulic fluid to a materials testing apparatus, the HPU having an electric motor and a pump, the method including controlling a pressure of the pressurized hydraulic fluid based on a first pressure set point to perform a first materials testing process, receiving an indication of a second pressure set point for a second materials testing process to be performed by the materials testing apparatus, and controlling the pressure of the pressurized hydraulic fluid based on the second pressure set point to perform the second materials testing process.

Description

[Background technology]

[0001] Servo-hydraulic materials testing machines (sometimes known as structural testing machines) are used to test physical properties of material specimens by applying a test force to the material specimen using a hydraulic actuator. The hydraulic actuator is typically driven by a hydraulic power unit configured to provide pressurized hydraulic fluid to the materials testing machine.

[0002] However, existing hydraulic power units used in materials testing applications operate inefficiently and cause excessively high power consumption.

[0003] It is an object of the present disclosure to at least alleviate one or more of the problems in the prior art. Summary of the Invention

[0004] In accordance with the present disclosure, there is provided a method for controlling a hydraulic power unit (HPU) that provides pressurized hydraulic fluid to a materials testing apparatus, the HPU having an electric motor and a pump, the method including controlling a pressure of the pressurized hydraulic fluid based on a first pressure set point to perform a first materials testing process, receiving an indication of a second pressure set point for a second materials testing process to be performed by the materials testing apparatus, and controlling the pressure of the pressurized hydraulic fluid based on the second pressure set point to perform the second materials testing process.

[0005] Optionally, the second pressure set point is less than the first pressure set point.

[0006] Optionally, controlling the pressure (eg, based on one or both of the first pressure set point and the second pressure set point) includes controlling a rotational speed of the electric motor.

[0007] Optionally, controlling the rotational speed of the electric motor comprises reducing the rotational speed of the electric motor such that energy consumption of the electric motor is reduced in response to the second pressure set point.

[0008] Optionally, controlling the pressure (eg, based on one or both of the first pressure set point and the second pressure set point) includes controlling a fluid displacement of the pump.

[0009] Optionally, controlling the fluid displacement of the pump includes reducing the fluid displacement of the pump such that energy consumption of the electric motor is reduced in response to the second pressure set point.

[0010] Optionally, controlling the pressure (e.g., based on one or both of the first pressure set point and the second pressure set point) includes controlling both a fluid displacement of the pump and a rotational speed of the electric motor, wherein one or both of the fluid displacement of the pump and the rotational speed of the electric motor are controlled in response to predetermined characterization data such that a combined operating efficiency of the electric motor and the pump is controlled.

[0011] Optionally, the method further comprises determining a flow rate of hydraulic fluid flowing through the pump and controlling one or both of a fluid displacement of the pump and a rotational speed of the electric motor depending thereon, the predetermined characterization data indicating one or both of a target fluid displacement of the pump and a target rotational speed of the electric motor depending on the flow rate.

[0012] Optionally, the method further comprises controlling fluid displacement of the pump in response to a target fluid displacement.

[0013] Optionally, the method further comprises controlling a rotational speed of the electric motor in response to the target rotational speed.

[0014] Optionally, the second pressure set point indication is determined in response to a user input received at a user interface.

[0015] Optionally, the second pressure set point indication is determined by a controller of the materials testing machine.

[0016] Optionally, the indication of the second pressure set point is determined by a remote computing device communicatively coupleable to the communications network, and receiving the indication includes receiving the indication from a server via the communications network.

[0017] Optionally, the indication of the second pressure set point is based on a prediction of a load demand for the second materials testing process.

[0018] Optionally, the prediction of the load demand of the second materials testing process is a prediction of a maximum load demand.

[0019] According to one embodiment of the present disclosure, a method is provided that includes obtaining an indication of a test configuration of a material testing process to be performed by a material testing machine, the material testing machine being configured to receive pressurized hydraulic fluid from a hydraulic power unit (HPU); determining a load demand of the material testing process based on the received indication of the test configuration; and providing an indication of a pressure set point to a controller based on the determined load demand, the controller being configured to control a pressure of the pressurized hydraulic fluid to perform the material testing process.

[0020] Optionally, the test configuration includes one or both of a material composition of the specimen and one or more test parameters corresponding to the material testing process.

[0021] Optionally, the load demand is a maximum load demand.

[0022] Optionally, determining the load demand of the materials testing process comprises predicting the load demand based on the obtained indication of the test configuration.

[0023] Optionally, the method further includes predicting load demands of the material testing process based on (eg, result) data corresponding to (eg, obtained) a plurality of previous material testing processes.

[0024] Optionally, the method further includes obtaining data (eg, results) corresponding to a plurality of previous material testing processes.

[0025] Optionally, the data includes respective indications of (eg, maximum) load demands for a plurality of previous material testing processes, each previous material testing process having a respective test configuration.

[0026] Optionally, the load demands of the materials testing process are predicted based on a machine learning model, the machine learning model being trained based on data corresponding to a plurality of previous materials testing processes.

[0027] According to one embodiment of the present disclosure, machine readable instructions are provided which, when executed by a processing circuit, cause the processing circuit to perform a method according to any of the methods described above.

[0028] According to one embodiment of the present disclosure, there is provided a computer program product comprising the above machine-readable instructions.

[0029] According to one embodiment of the present disclosure, there is provided a (eg, non-transitory) computer readable medium containing the above machine readable instructions.

[0030] According to one embodiment of the present disclosure, a controller is provided that controls a hydraulic power unit (HPU) having an electric motor and a pump, the HPU configured to provide pressurized hydraulic fluid to a materials testing apparatus, the controller configured to control a pressure of the pressurized hydraulic fluid based on a first pressure set point to perform a first materials testing process, receive an indication of a second pressure set point for a second materials testing process to be performed by the materials testing apparatus, and control the pressure of the pressurized hydraulic fluid based on the second pressure set point to perform the second materials testing process.

[0031] According to one embodiment of the present disclosure, there is provided a hydraulic power unit (HPU) including a controller according to any of the controllers described above.

[0032] According to one embodiment of the present disclosure, there is provided a system including a hydraulic power unit according to the hydraulic power unit described above, and a material testing device configured to receive pressurized hydraulic fluid from the hydraulic power unit.

[0033] According to one embodiment of the present disclosure, an apparatus is provided that is configured to obtain instructions of a test configuration of a materials testing process to be performed by a materials testing apparatus, determine a load demand for the testing process based on the obtained instructions of the test configuration, and provide an indication of a pressure set point to a controller based on the determined load demand, the controller being configured to control a pressure of a pressurized hydraulic fluid to perform the materials testing process.

[0034] According to one embodiment of the present disclosure, there is provided a hydraulic power unit (HPU) for providing pressurized hydraulic fluid to a materials testing machine, the HPU comprising: a reservoir for storing hydraulic fluid, a pump for pumping the hydraulic fluid to an outlet connectable to the materials testing machine, an alternating current (AC) electric motor located in the reservoir configured to drive the pump, and an electric inverter for providing an AC power supply to the electric motor, the electric inverter configured to control an operating point of the electric motor. Optionally, the HPU is configured to provide hydraulic fluid to the outlet at a target pressure.

[0035] Optionally, the HPU is configured to provide hydraulic fluid to the outlet at a target pressure.

[0036] Optionally, the target pressure is set based on the received signal.

[0037] Optionally, the electric inverter is configured to control an operating point of the electric motor by controlling any one or more of the voltage of the AC power supply, the current of the AC power supply, the frequency of the AC power supply, and the phase of the AC power supply.

[0038] Optionally, the electric inverter is configured to control an operating point of the electric motor by controlling one or more of a current of the AC power supply, a frequency of the AC power supply, and a phase of the AC power supply such that an operating efficiency of the electric motor is altered to maintain the operating point.

[0039] Optionally, the pump is a variable displacement pump that controls the flow rate of hydraulic fluid from the outlet.

[0040] Optionally, the HPU comprises a controller configured to control the rotational speed of the electric motor to maintain hydraulic fluid at the outlet at a target pressure.

[0041] Optionally, the controller has an input for receiving a pressure signal indicative of the target pressure.

[0042] Optionally, the controller has a first output providing a motor control signal to an electric inverter for controlling the rotational speed of the electric motor.

[0043] Optionally, the motor control signal indicates one or more parameters of the AC power supply.

[0044] Optionally, the motor control signal is indicative of a target pressure.

[0045] Optionally, the controller is configured to control the fluid displacement of the pump to maintain hydraulic fluid at the outlet at a target pressure.

[0046] Optionally, the controller has a second output that provides a pump control signal to the pump to control the fluid displacement of the pump.

[0047] Optionally, the pump control signal indicates a target displacement of the pump.

[0048] Optionally, the pump control signal indicates a target pressure.

[0049] Optionally, the pump is operable as a pressure compensated variable displacement pump having an adjustable pressure set point, and the controller is configured to control the fluid displacement of the pump by controlling the adjustable pressure set point.

[0050] Optionally, the controller is configured to control both the speed of the electric motor and the fluid displacement of the pump, where one or both of the fluid displacement of the pump and the rotational speed of the electric motor are controlled in response to predetermined characterization data such that a combined operating efficiency of the electric motor and the pump is controlled.

[0051] Optionally, the controller is configured to determine a flow rate of hydraulic fluid flowing through the pump and to control one or both of a fluid displacement of the pump and a rotational speed of the electric motor depending thereon, and the predetermined characterization data indicates one or both of a target fluid displacement of the pump and a target rotational speed of the electric motor depending on the flow rate.

[0052] Optionally, the controller is configured to control fluid displacement of the pump based on a target fluid displacement.

[0053] Optionally, the controller is configured to control the rotational speed of the electric motor based on the target rotational speed.

[0054] Optionally, the electric motor is configured to be submerged in hydraulic fluid in the reservoir in use.

[0055] Optionally, the pump is located within the reservoir.

[0056] Optionally, the pump is configured to be submerged in hydraulic fluid in the reservoir in use.

[0057] Optionally, the HPU includes a cooling pump disposed in the reservoir, and the motor is configured to drive the cooling pump to pump hydraulic fluid to a cooling device external to the hydraulic power unit.

[0058] Optionally, the cooling pump is configured to be submerged in hydraulic fluid in the reservoir in use.

[0059] According to one embodiment of the present disclosure, there is provided a system including any of the HPUs described above and a materials testing device configured to receive pressurized hydraulic fluid from the HPU.

[0060] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0061] [Figure 1] FIG. 1 illustrates a schematic diagram of an exemplary system including a hydraulic power unit and a material testing device, according to one embodiment of the present disclosure.

[0062] [Diagram 2] FIG. 1 illustrates a schematic diagram of an exemplary hydraulic power unit according to an embodiment of the present disclosure.

[0063] [Diagram 3] FIG. 2 illustrates a schematic diagram of another exemplary hydraulic power unit according to an embodiment of the present disclosure.

[0064] [Figure 4] FIG. 2 illustrates a schematic diagram of another exemplary hydraulic power unit according to an embodiment of the present disclosure.

[0065] [Diagram 5] FIG. 2 illustrates a schematic diagram of another exemplary hydraulic power unit according to an embodiment of the present disclosure.

[0066] [Figure 6] FIG. 1 illustrates a schematic diagram of an exemplary apparatus according to various embodiments of the present disclosure.

[0067] [Figure 7] 1 is an exemplary flowchart that generally illustrates a method according to an embodiment of the present disclosure.

[0068] [Figure 8] 1 is another exemplary flow chart that generally illustrates a method according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0069] 1 illustrates a schematic diagram of an exemplary system 100 according to an embodiment of the present disclosure. The system 100 can provide for testing of physical properties of a material sample. The material sample can be, for example, a sample of material produced by a production process, the physical properties of which can be tested to, for example, evaluate the quality of the production process.

[0070] The system 100 includes a hydraulic power unit (HPU) 110 (sometimes referred to as a hydraulic power pack) and a (e.g., servo-hydraulic) materials testing machine 130. Optionally, the system 100 further includes one or both of a controller 140 and a load determiner 142. In some examples, the controller 140 can be configured to implement a method according to an embodiment of the present disclosure, as described below with respect to FIG. 7. In some examples, the load determiner 142 can be configured to implement a method according to an embodiment of the present disclosure, as described below with respect to FIG. 8.

[0071] The materials testing machine 130 may be configured to perform one or more materials testing processes using hydraulic actuation means to apply one or both of force and torque along one or more axes of a material sample, thereby enabling physical properties of the material sample to be evaluated.

[0072] A material testing process can include, for example, any type of mechanical or physical material testing. In some examples, a material testing process may depend on one or more corresponding test parameters, which can indicate, for example, how one or more test variables are controlled (e.g., with respect to one or more axes of a material specimen) according to the material testing process.

[0073] In some examples, the one or more test variables may include any one or more of actuation displacement (e.g., linear or rotational), actuation force, actuation torque, strain induced in the material sample, and temperature of the material sample (e.g., which may result from self-heating of the material sample).

[0074] In some examples, the material testing process may include any type of material testing process in which any one or more test variables are controlled, such as, for example, the test variables described above. In some examples, the material testing process may include fatigue testing, including, for example, high cycle fatigue testing (e.g., one or both of the actuation force and actuation displacement may be controlled), low cycle fatigue testing (e.g., the strain induced in the material specimen may be controlled), and combined fatigue testing (e.g., the actuation force and the temperature of the material specimen may be controlled), crack propagation testing (e.g., the actuation force may be controlled), fracture toughness testing (e.g., one or both of the actuation displacement and actuation force may be controlled), biaxial testing (e.g., actuation along a first axis (e.g., linear) of the material specimen), and other types of testing. The testing methods may include any one or more of: variable amplitude (spectral) load testing (e.g., where the actuation force or displacement may be controlled, and the actuation force or torque along a second axis orthogonal to the first axis of the material specimen may be controlled); variable amplitude (spectral) load testing (e.g., where the actuation force may be controlled); static testing (e.g., where any one or more of the actuation displacement, actuation force, and strain induced in the material specimen may be controlled); and any other type of mechanical or physical testing, including, but not limited to, stress testing, tensile testing, compression testing, torsion testing, and strain testing.

[0075] The HPU 110 can be connected to the materials testing machine 130 and can be configured, when in use, to provide pressurized hydraulic fluid to the materials testing machine 130 to enable the materials testing machine 130 to perform one or more materials testing processes.

[0076] The HPU 110 comprises an electric motor 112, a pump 114, a reservoir 116, an outlet 118 (which may be known as "pressure"), and an inlet 120 (which may be known as "return"). Optionally, as described further below, the HPU 110 may further comprise any one or more of a motor driver circuit 122, a user interface 124, and a communication circuit 126.

[0077] The electric motor 112 is configured to drive a pump 114, which is configured to pump hydraulic fluid from a reservoir 116 configured to store hydraulic fluid to an outlet 118, thereby providing pressurized hydraulic fluid to the outlet 118. The outlet 118 of the HPU 110 can be configured to provide pressurized hydraulic fluid to an inlet 134 of the material testing machine 130 via a fluid coupling means, such as one or more pipes, as indicated by arrow 160. The inlet 120 of the HPU 110 can be configured to receive hydraulic fluid from an outlet 136 of the material testing machine 130 via a fluid coupling means, as indicated by arrow 162. The inlet 120 of the HPU 110 can receive hydraulic fluid from the outlet 136 of the material testing machine 130, for example, after the hydraulic fluid has flowed through and been utilized by the hydraulic actuation means of the material testing machine 130, for example, during the performance of a material testing process. The inlet 120 of the HPU 110 may be further configured to return the received hydraulic fluid to the reservoir 116 .

[0078] Unless otherwise specified, electric motor 112 may include any type of electric motor, including, for example, any type of alternating current (AC) electric motor, including any AC electric motor having any number of phases, such as one phase or three phases, any type of direct current (DC) electric motor, and any other type of electric motor.

[0079] In some examples, the HPU 110 may optionally include a motor driver circuit 122 that may be configured to provide power to the electric motor 112 in accordance with the present techniques. In some examples in which the electric motor 112 includes a three-phase AC electric motor and the motor driver circuit 122 is not present, the HPU 110 may optionally include a starting circuit (e.g., a star-delta starter, or any other type of starting circuit, etc.) (not shown) configured to control the electric motor 112 during starting.

[0080] In some examples, the motor driver circuit 122 can be configured to control the rotational speed of the electric motor 112 in accordance with the present techniques. As described further below in connection with FIGS. 2-5, in some examples, the motor driver circuit 122 can be controlled by the controller 140 to control the rotational speed of the electric motor 112 to control the output pressure of the HPU 110 based on a (e.g., selectively adjustable) pressure set point (e.g., to maintain the output pressure of the HPU 110 at a target pressure, the target pressure being based on the pressure set point, e.g., the target pressure is equal to or greater than the pressure set point). As used herein, the output pressure of the HPU 110 is used to refer to the pressure of the pressurized hydraulic fluid provided to the outlet 118 of the HPU 110, which can substantially correspond to the pressure of the pressurized hydraulic fluid provided to the materials testing machine 130.

[0081] In some examples, the motor driver circuit 122 may include a control means (not shown) operable to receive an indication of a pressure set point and control the output pressure of the HPU 110 based on the pressure set point by controlling the rotational speed of the electric motor 112. The control means may be integrated within the motor driver circuit 122 or may be external to the motor driver circuit 122 and operatively coupled thereto. The control means may include, for example, an electronic control means comprising a processing circuit operable to implement a control algorithm, such as a proportional-integral-derivative (PID) based control algorithm, or any other type of control algorithm, or any other type of control means. In some examples, the control means of the motor driver circuit 122 may be operable to control the output pressure of the HPU 110 based on both the pressure set point and an indication of a measured output pressure of the HPU 110, the measured output pressure being provided, for example, by a pressure sensor (not shown) or any other type of sensor operable to measure one or more metrics indicative of the output pressure of the HPU 110. In other words, the control means may be configured to implement closed loop control based on feedback that includes an indication of the output pressure of HPU 110. In other examples, as described further below, controller 140 may implement the functionality of the control means described immediately above.

[0082] In some examples, the rotational speed of the electric motor 112 can be controlled in accordance with the present techniques by providing a motor control signal (not shown) to the motor driver circuit 122. In examples where the motor driver circuit 122 includes a control means as described above, the motor control signal can include, for example, an indication of a pressure set point. Alternatively, in other examples, the motor control signal can include, for example, an indication of one or more parameters of the electrical power supply provided by the motor driver circuit 122 to the electric motor 112.

[0083] The motor driver circuit 122 may depend on the type of electric motor 112. For example, in examples where the electric motor 112 is an AC electric motor, the motor driver circuit 124 may include an electrical inverter (which may also be referred to as, for example, a variable frequency drive, an AC drive, or a variable speed drive). In these examples, the power supply provided by the motor driver circuit to the electric motor 112 may be an AC power supply. The electrical inverter may be configured to control any one or more of the voltage of the AC power supply, the current of the AC power supply, the frequency of the AC power supply, and the phase of the AC power supply.

[0084] In examples where the electric motor 112 is a DC motor, the motor driver circuit 122 may include, for example, a half-bridge motor driver, a full-bridge motor driver, or any other type of driver circuit suitable for driving a DC motor at variable rotational speeds. In these examples, the power supply provided to the electric motor 112 may include a pulse width modulated DC power supply, and the motor driver circuit 122 may be configured, for example, to control a pulse width modulation (PWM) duty cycle of the power supply.

[0085] It has been observed that existing systems used for material testing purposes typically operate the electric motor of the HPU in an inefficient and wasteful manner, resulting in excessively high power consumption of the HPU. Advantageously, as described further below, in some embodiments, the present disclosure provides an HPU having an AC electric motor, the operating point of which is controlled by an electric inverter, which may enable the AC electric motor, in some examples, to have improved operating efficiency.

[0086] In some examples, the motor driver circuit with electric inverter 122 can be configured to control an operating point of the electric motor 112. As will be appreciated, the operating point of the electric motor can refer to the rotational speed output torque point at which the electric motor 112 is operating. The operating point can correspond to an intersection of a torque-speed curve of the electric motor 112 and a torque-speed curve of a system driven by the electric motor 112, such as the pump 114, depending on a corresponding hydraulic circuit fluidly coupled thereto. By controlling one or more parameters of the (AC) electrical supply, the motor driver circuit with electric inverter 122 can be operable to control the torque-speed curve of the electric motor 112 and thereby control its operating point for a given torque-speed curve of the system.

[0087] In some examples, the motor driver circuit with electrical inverter 122 can be configured to control an operating point of the electric motor 112 by controlling one or more parameters of the (AC) power supply such that the operating efficiency of the electric motor 112 is altered to maintain the operating point. The operating efficiency of the electric motor may depend on the ratio of the input power (e.g., the power provided to the electric motor 112) to the output power (e.g., the power provided to the load). The output power may depend on the operating point of the electric motor 112. For a given operating point of the electric motor 112, the motor driver circuit with electrical inverter 122 can be configured to control one or more parameters of the (AC) power supply provided to the electric motor 112 to maintain the operating point and thus the output power, and reduce the input power, thereby increasing the operating efficiency of the electric motor 112 for that operating point. To do so, the motor driver circuit with electrical inverter 122 can control one or more parameters of the AC power supply, for example, to reduce power losses associated with the electric motor 112 (e.g., copper losses in the stator windings and rotor windings of the electric motor 112, or any other losses). In modifying the operating efficiency to maintain the operating point, the electric inverter may use any type of control technique including, for example, so-called scalar control, so-called vector control, or any other type of control technique. The electric inverter may utilize open loop control or closed loop control based on feedback provided by one or more sensors (not shown) operable to measure one or more metrics indicative of the operating point of the electric motor 112.

[0088] Unless otherwise specified, pump 114 may include any type of pump, including, for example, any type of pump operable to convert mechanical or electrical energy into fluid power. In some examples, pump 114 may include any one of a non-positive displacement pump, such as, for example, a centrifugal pump or any other type of non-positive displacement pump, a positive displacement pump, and any other type of pump.

[0089] In examples where the pump 114 includes a positive displacement pump, the pump 114 may include, for example, any one of a reciprocating pump, a rotary pump, an external gear pump, an internal gear pump, a lobe pump, a gerotor pump, any other type of gear pump, a screw pump, a vane pump, a piston pump including an axial piston pump and a radial piston pump, or any other type of positive displacement pump. In some examples, the pump 114 may include a fixed displacement pump in which the fluid displacement (volume of fluid displaced per pump cycle) is fixed, or may otherwise be operable as a fixed displacement pump. Alternatively, the pump 114 may be a variable displacement pump in which the fluid displacement may be controllable. As an illustrative example, the pump 114 may include an axial variable displacement pump having an adjustable swashplate, the angle of which may be adjusted to control the fluid displacement of the pump 114. However, this is merely one example of a variable displacement pump, and the disclosure is not so limited.

[0090] In examples where the pump 114 is a variable displacement pump, the pump 114 may be operable as a pressure compensated variable displacement pump configured to control its fluid displacement to regulate its output pressure to substantially correspond to a pressure set point. The pressure set point may be fixed or adjustable. In some examples, the pump 114 may be configured to receive an indication of a pressure set point to set the pressure set point of the pump 114.

[0091] In examples where the pump 114 is a variable displacement pump, the pump 114 may comprise a pressure compensation control means (not shown) operable to control the output pressure of the HPU 110 based on a pressure set point by controlling the fluid displacement of the pump 114. The pressure compensation control means may be integrated within the pump 114 or may be external to the pump 114 and operatively coupled thereto. The pressure compensation control means may include, for example, a hydraulic control means such as a pressure compensation valve, a mechanical control means, an electronic control means, any combination thereof, or any other type of control means. In some examples, the pressure compensation control means may control the fluid displacement of the pump 114 based on a fixed pressure set point. In other examples, the pressure compensation control means may be configured to receive an indication of a pressure set point and control the fluid displacement of the pump 114 based on the received indication. In some examples, the pressure compensation control means may comprise, for example, an electronic control means comprising a processing circuit operable to implement a control algorithm, for example, a proportional integral derivative (PID) based control algorithm, or any other type of control algorithm. In some examples, the pressure compensation control means may control the output pressure of the HPU 110 based on both a pressure set point and an indication of a measured output pressure of the HPU 110, where the measured output pressure may be provided, for example, by a pressure sensor (not shown) or any other type of sensor operable to measure one or more metrics indicative of the output pressure of the HPU 110. In some examples, the pressure sensor may be integrated within the pump 114. In other examples, the pressure sensor may be external to the pump 114 and operably coupled to its pressure compensation control means.

[0092] In some examples, as described further below, the controller 140 may implement the functionality of the pressure compensation control means described above.

[0093] In examples where pump 114 is a variable displacement pump, the fluid displacement of pump 114 may be controlled in accordance with the present techniques by providing a pump control signal to pump 114. In examples where pump 114 includes a pressure compensation control means as described above, the pump control signal may include, for example, an indication of a pressure set point. Alternatively, in other examples, the pump control signal may include, for example, an indication of the fluid displacement of pump 114.

[0094] In some examples, one or both of the electric motor 112 and the pump 114 may be located within a reservoir 116 (not shown). In these examples, at least when in use, one or both of the electric motor 112 and the pump 114 may be at least partially submerged in hydraulic fluid stored in the reservoir 116. In these examples, the hydraulic fluid stored in the reservoir 116 may at least partially attenuate acoustic noise generated by one or both of the electric motor 112 and the pump 114. Advantageously, these examples may provide a relatively quiet HPU (e.g., without using expensive acoustic cladding) that may advantageously allow the HPU to be acceptably located in the same room as the material testing machine 130, thereby avoiding the use of hydraulic infrastructure that places the HPU in a room separate from the material testing machine 130, for example. Additionally, the hydraulic fluid stored in the reservoir 116 may provide thermal cooling for one or both of the electric motor 112 and the pump 114. Such thermal cooling may be particularly effective, for example, in examples where the hydraulic fluid is actively cooled as described below.

[0095] In some examples, the HPU 110 may optionally include a cooling pump (not shown). The cooling pump may be disposed within the reservoir 116. The electric motor 112 may be configured to drive the cooling pump to pump hydraulic fluid to a cooling device (not shown) external to the HPU 110. In these examples, at least during use, the cooling pump may be at least partially submerged in the hydraulic fluid stored within the reservoir 116, which may advantageously provide benefits similar to those discussed above in connection with the electric motor 112 and pump 114.

[0096] Returning to the system 100 as a whole, the materials testing machine 130 includes a hydraulic actuator 132 , an inlet 134 , and an outlet 136 .

[0097] The hydraulic actuator 132 may be configured to apply one or both of a force and a torque along one or more axes of a material specimen of a material testing process. The hydraulic actuator 132 may include any type of hydraulic actuator, including, for example, but not limited to, a linear hydraulic actuator including a hydraulic cylinder, a rotary hydraulic actuator, a hydraulic motor, a biaxial hydraulic actuator, any other type of hydraulic actuator, and any combination thereof. In some examples, the hydraulic actuator 132 of the material testing apparatus 130 may be configured to operate at a force range of less than 10 MN, less than 5 MN, or between 10 kN and 5 MN, although other force ranges may be possible. The inlet 134 of the material testing apparatus 130 may be configured to receive pressurized hydraulic fluid from the outlet 118 of the HPU 110 via a fluid coupling means, as indicated by arrow 160. The inlet 134 of the material testing apparatus 130 may be further configured to provide at least a portion of the pressurized hydraulic fluid received from the outlet 118 of the HPU 110 to the hydraulic actuator 132 to enable testing of the material specimen according to the material testing process. The outlet 136 of the materials testing machine 130 may be configured to provide hydraulic fluid to the HPU outlet 120 via a fluid coupling, as indicated by arrow 162. The outlet 136 of the materials testing machine 130 may provide hydraulic fluid to the outlet 120, for example, after the hydraulic fluid has flowed through and been utilized by the hydraulic actuator 132 of the materials testing machine 130.

[0098] Existing systems used for material testing purposes typically utilize HPUs having electric motors and pumps, and it has been observed that for a given load, the electric motors and pumps operate inefficiently, resulting in a combined operating efficiency of the electric motor and pump that is non-optimal or inefficient for the given load.

[0099] Furthermore, the HPUs in such existing systems are typically configured to provide pressurized hydraulic fluid to the materials testing equipment at a fixed (i.e., non-adjustable) output pressure regardless of the pressure requirements of the materials testing process being performed. In such systems, the pressure of the hydraulic fluid emanating from the HPU may be adjusted by the materials testing equipment downstream of the HPU to meet the pressure requirements of a given materials testing process.

[0100] Thus, in situations where the fixed output pressure of the HPU of such existing systems exceeds the pressure requirements of a given material testing process, such HPUs may unnecessarily and wastefully pressurize the hydraulic fluid at its output beyond the pressure required to successfully conduct the material testing process. Furthermore, in such situations, it may be necessary to reduce the pressure of the hydraulic fluid output by the HPU downstream of the HPU (e.g., using a pressure relief valve) to meet the requirements of the material testing process, which may have additional associated energy costs, such as requiring the implementation of a cooling system having an associated energy consumption required to handle the heat of the hydraulic fluid discharged by the pressure relief valve. Thus, existing solutions are inefficient and result in excessively high power consumption, especially when conducting material testing processes having pressure requirements that are (e.g., substantially) lower than the output pressure of the HPU.

[0101] Advantageously, as described further below, the present disclosure provides an HPU having an electric motor and a pump configured to provide pressurized hydraulic fluid to a materials testing apparatus, where one or both of the electric motor and the pump can be controlled to improve their operating efficiency while maintaining a target HPU output pressure. Additionally, the output pressure of the HPU can be controllable and adjusted to meet the pressure requirements of a particular materials testing process, thereby providing a more efficient HPU for materials testing purposes.

[0102] Returning to FIG. 1, in some examples, the system 100 can include a controller 140 that can be configured to control the output pressure of the HPU 110 in accordance with the present techniques.

[0103] In some examples, the controller 140 can be configured to control the output pressure of the HPU 110 based on a (e.g., selectively adjustable) pressure set point. For example, the controller 140 can be configured to maintain the output pressure of the HPU 110 at a target pressure, where the target pressure is based on the pressure set point (e.g., the target pressure is equal to or greater than the pressure set point).

[0104] In some examples, controller 140 may have a first input (not shown) configured to receive an indication of (e.g., a signal including) a pressure set point. Additionally or alternatively, as described further below in connection with FIGS. 2-5, controller 140 may have a second input (not shown) configured to receive an indication of (e.g., a signal including) a measured output pressure of HPU 110.

[0105] As described further below, the pressure set point indication can be determined based on a test configuration of the material testing process performed by the materials testing machine 130. In some examples, the determination can include a prediction of a (e.g., maximum) load demand for the material testing process. The pressure set point indication can be received from any other user interface communicatively coupled to the controller 140, including, but not limited to, a user interface, such as the user interface 124 of the HPU 110, or a user interface associated with the materials testing machine 130, a device, such as the load determiner 142, a computing device, including, for example, a computing device associated with the materials testing machine 130 (e.g., a controller of the materials testing machine 130), or a remote computing device communicatively coupled to the controller 140.

[0106] In some examples, the pressure set point indication can correspond to a (e.g., default) pressure set point for the material testing process. In some examples, the computing device can determine the pressure set point indication based on, for example, the material testing process. For example, the computing device can access a memory (which can be included in the computing device or communicatively coupled thereto) configured to store one or more (e.g., default) indications of pressure set points according to a respective test configuration, and the computing device can determine the pressure set point indication by retrieving the indication from the memory. In some examples, the computing device can be associated with (e.g., included therein or communicatively coupled to, for example, its controller) the material testing apparatus 130. In other examples, the computing device can include a remote computing device communicatively coupled to the controller 140 via a communication network (not shown), such as, for example, a local area network (LAN) or a wide area network (WAN). The communication network can be wired or wireless, or a combination of wired and wireless.

[0107] In some examples, the indication of the pressure set point may include, for example, a pressure set point value or any other value based thereon or otherwise indicative of the pressure set point. In some examples, the indication of the pressure set point may include, for example, an indication of a force demand (e.g., of the hydraulic actuator 132 of the material testing machine 130 of the material testing process). In these examples, the controller 140 may be configured to convert the force demand to a pressure set point (e.g., determine the pressure set point based on the force demand) using any suitable method or technique. In some examples, the controller 140 may convert the force demand to a pressure set point, for example, based on predetermined hydraulic actuator characterization data. The predetermined hydraulic actuator characterization data may indicate a relationship between an input pressure (e.g., of hydraulic fluid provided to the hydraulic actuator 132) and a force output by the hydraulic actuator 132. For example, the hydraulic actuator characterization data may indicate a first actuation force of the hydraulic actuator 132 relative to a first input pressure. In these examples, the force demand may be converted to a pressure set point by scaling the first input pressure based on a ratio of the force demand to the first actuation force. As an illustrative example, the first actuation force may correspond to a full-scale force of the hydraulic actuator 132 (e.g., 100 kN), and the first input pressure may correspond to a maximum rated input pressure (e.g., 210 bar). If the force demand was, for example, half of the full-scale force of the hydraulic actuator 132 (e.g., 50 kN), the force demand may be converted to a corresponding pressure set point by scaling the maximum rated input pressure by a factor of half (e.g., to give a pressure set point of 105 bar). However, this is merely one illustrative example, and the disclosure is not so limited. In some examples, the predetermined hydraulic actuator characterization data may be indicative of any given actuation force of the hydraulic actuator 132 for any corresponding input pressure, and the force demand may be any value associated with that given actuation force. In other examples, the predetermined hydraulic actuator characterization data may include any other data indicative of a relationship between the input pressure and the force output by the hydraulic actuator 132.

[0108] In some examples, a conversion process similar to that described above may be utilized to convert a pressure demand to a force demand, while in other examples, any other method or technique may be used to convert a force demand to a pressure demand (or set point) or vice versa.

[0109] In some examples, the controller 140 can be configured to control the rotational speed of the electric motor 112 to control the output pressure of the HPU 110 based on a pressure set point. In these examples, the controller 140 can have a first output (not shown) configured to provide the motor control signal described above to the motor driver circuit 122 to control the rotational speed of the electric motor 112 accordingly.

[0110] In examples where pump 114 includes a variable displacement pump, controller 140 can be configured to control the fluid displacement of pump 114 to control the output pressure of HPU 110 based on a pressure set point. In these examples, controller 140 can have a second output (not shown) configured to provide the pump control signal described above to pump 114 and control the fluid displacement of pump 114 accordingly.

[0111] In examples in which pump 114 includes a variable displacement pump, controller 140 may be configured to control both the rotational speed of electric motor 112 (e.g., via a motor control signal) and the fluid displacement of pump 114 (e.g., via a pump control signal) to control the output pressure of HPU 110 based on a pressure set point. In these examples, controller 140 may be configured to control one or both of the fluid displacement of pump 114 and the rotational speed of electric motor 112 in response to predetermined characterization data such that the combined operating efficiency of electric motor 112 and pump 114 is controlled.

[0112] The predetermined characterization data may, for example, indicate a target fluid displacement of the pump 114 as a function of a flow rate of hydraulic fluid flowing through the pump (e.g., provided to the outlet 118). Additionally or alternatively, the predetermined characterization data may, for example, indicate a target rotational speed of the electric motor 112 as a function of the flow rate. The target fluid displacement and target rotational speed may provide a given flow rate while allowing the combined operating efficiency of the electric motor 112 and the pump 114 to be substantially optimized for that flow rate. The predetermined characterization data may be based, for example, on characterization measurements of the pump 114 and the electric motor 112, or modeling of the pump 114 and the electric motor 112, or any other method.

[0113] In some examples, the controller 140 may be configured to determine a flow rate of hydraulic fluid flowing through the pump 114 and control one or both of a fluid displacement of the pump 114 and a rotational speed of the electric motor 112 in response to the determined flow rate. The flow rate may be determined in any manner. For example, the flow rate may be measured using any type of flow sensor (not shown). In other examples, the flow rate may be inferred based on other parameters indicative of the flow rate that may be measured or otherwise known, including, for example, the rotational speed of the electric motor 112 and the fluid displacement of the pump 114.

[0114] In some examples, the controller 140 can be configured to control one or both of the fluid displacement of the pump 114 and the rotational speed of the electric motor 112 based on the predetermined characterization data and the determined flow rate. In some examples, the controller 140 can be configured to control the fluid displacement of the pump 114 based on a target fluid displacement as indicated by the characterization data. Additionally or alternatively, the controller 140 can be configured to control the rotational speed of the electric motor 112 based on a target rotational speed as indicated by the characterization data.

[0115] In some examples, the controller 140 can be configured to control the output pressure of the HPU 110 based on a first pressure set point for performing a first material testing process (e.g., maintain the output pressure of the HPU at a first target pressure, where the first target pressure is based on the first pressure set point, e.g., the first target pressure is equal to or greater than the first pressure set point), and receive an indication of a second pressure set point for a second material testing process performed by the material testing apparatus 130 and control the output pressure of the HPU 110 based on the second pressure set point (e.g., substantially maintain the output pressure of the HPU at a second target pressure, where the second target pressure is based on the second pressure set point, e.g., the second target pressure is equal to or greater than the second pressure set point).

[0116] In some examples, the first pressure set point may correspond to or be otherwise based on, for example, a default pressure set point, e.g., HPU 110 is configured to control based on the default pressure set point when initially powered up, or, for example, an indication of the first set point previously received by controller 140.

[0117] In some examples, the second pressure set point may be less than the first pressure set point. Thus, controlling the output pressure of the HPU 110 based on the second pressure set point may reduce energy consumption of the HPU 110 compared to controlling the output pressure of the HPU 110 based on the first pressure set point.

[0118] Controlling the output pressure of HPU 110 based on a first pressure set point may include any method of controlling the output pressure of the HPU based on a pressure set point, including, for example, any method of controlling the output pressure of HPU 110 based on a pressure set point as disclosed herein above. Similarly, controlling the output pressure of HPU 110 based on a second pressure set point may include any method of controlling the output pressure of HPU 110 based on a pressure set point, including, for example, any method of controlling the output pressure of HPU 110 based on a pressure set point as disclosed herein above.

[0119] The controller 140 may be implemented in either hardware, software, firmware, or any combination thereof. In some examples, the controller 140 may comprise a processing circuit, such as, for example, a microcontroller, a programmable logic controller, or any other type of processing circuit.

[0120] Referring again to the system 100 overall, the system 100 may include a load determiner 142 that may be configured to determine a load demand of a material testing process performed by the material testing machine 130 and enable the HPU 110 to control its output pressure based on the determined load demand. As used herein, a load demand of a material testing process may correspond to, for example, a pressure demand (e.g., of a pressurized hydraulic fluid provided to the material testing machine 130) or a force demand (e.g., of the hydraulic actuator 132) of the material testing process.

[0121] In some examples, the load determiner 142 can be configured to obtain an indication of a test configuration of a material testing process to be performed by the material testing machine, determine a load requirement for the test process based on the received indication of the material testing configuration, and provide an indication of a pressure set point to the controller 140 based on the determined load requirement. The load requirement can correspond, for example, to a maximum load requirement of the material testing process, e.g., a maximum pressure or maximum actuation force that the material testing process may require to be successfully performed. In other words, the load requirement can indicate at least a minimum output pressure of the HPU 110 that is required for the material testing process to be successfully performed. The pressure set point indication can include, for example, a pressure set point value or any other value based thereon or otherwise indicative of a pressure set point, including, for example, an indication of a force requirement.

[0122] In some examples, the test configuration can include any one or more of the material compositions of the material test specimen and one or more test parameters that can indicate how one or more test variables are controlled according to the material testing process, for example, including but not limited to any of the test variables disclosed herein.

[0123] In some examples, the load determiner 142 can have an input (not shown) configured to receive a signal including instructions for a test configuration of a materials testing process. The instructions for the test configuration of a testing process can be received from a user interface, such as, for example, the user interface 128 of the HPU 110 or any other user interface communicatively coupleable with the load determiner 142, a computing device, including, for example, a computing device associated with a materials testing apparatus 130, such as any computing device associated with a materials testing apparatus 130 disclosed herein, a remote computing device, including, for example, any remote computing device disclosed herein, or any other computing device.

[0124] In some examples, the load determiner 142 may have an output (not shown) configured to provide a signal to the controller 140 that includes an indication of the pressure set point.

[0125] In some examples, the materials testing process may correspond to a so-called force-controlled testing process, where the actuation force of the hydraulic actuator 132 of the materials testing machine 130 is the controlled variable. In these examples, the force demand may be known and therefore the load demand for that materials testing process may be determinable solely from the test configuration.

[0126] In some examples, the actuation force may not be a controlled variable of the material testing process. For example, the material testing process may correspond to so-called strain-controlled testing, or any other type of testing process in which the actuation force is not a controlled variable. In these examples, the load demand of the material testing process may depend, for example, on the material composition of the material specimen being tested or on the test parameters. In these examples, the load demand may be determined based on result data corresponding to a previous test having the same test configuration, the result data including an indication of the load demand for that test configuration. In other examples, the load demand may be predicted based on the test configuration. For example, the load demand may be predicted based on result data corresponding to one or more previous test processes. The result data may include, for example, a respective indication of a (e.g., maximum) load demand for each of one or more previous test processes, each test process having a respective test configuration.

[0127] In some examples, the result data may correspond to one or more test processes having respective test configurations that differ from the acquired test configuration, in these examples, the load demand for the test configurations may be determined based on the result data and the difference or differences between the acquired test configuration and the test configuration(s) in the result data.

[0128] As an illustrative example, the acquired test configuration can include a first material composition and a first test parameter, and the result data can include data corresponding to a previous test configuration including the first test parameter but including a second material composition, where the second material composition is different from the first material composition. Based on the first test parameter and the difference between the first material composition and the second material composition, the load demand of the acquired test configuration can be predicted. For example, it can be known or determined (e.g., via modeling) how the difference between the first material composition and the second material composition affects the physical properties of the material specimen, and the load demand can be predicted based thereon. However, this is merely one illustrative example, and the disclosure is not so limited.

[0129] In some examples, the load demand of the obtained test configuration may be predicted based on a machine learning model (e.g., a neural network, etc.), where the machine learning model is trained based on outcome data including respective indications of (e.g., maximum) load demands for a plurality of previous test processes, each previous test process having a respective test configuration. In these examples, the load determiner 142 may include the trained machine learning model. In some examples, the load determiner 142 may be configured to train the machine learning model. In other examples, the machine learning model may be trained by a computing device communicatively coupled to the load determiner 142, including, but not limited to, any computing device disclosed herein.

[0130] In some examples, the load determiner 142 may obtain data (e.g., result data) from a memory accessible by the load determiner 142. The memory may be included within the load determiner 142 or may be external to and communicatively coupled to the load determiner 142. The memory may be included within any computing device disclosed herein, for example. In some examples, the load determiner 142 may be operable to convert a pressure demand to a force demand or vice versa, according to any examples disclosed herein.

[0131] The load determiner 142 may be implemented in either hardware, software, firmware, or any combination thereof. In some examples, the load determiner 142 may comprise a processing circuit, such as, for example, a microcontroller, a programmable logic controller, or any other type of processing circuit.

[0132] Referring back to the system 100 as a whole, although the controller 140 and the load determiner 142 are shown in FIG. 1 as being separate from the HPU 110 and the material testing machine 130, this is merely one illustrative example and the disclosure is not so limited. In some examples, the HPU 110 can include one or both of the controller 140 and the load determiner 142. In other examples, one or both of the controller 140 and the load determiner 142 can be external to the HPU 110 and communicatively coupled to the HPU 110. For example, one or both of the controller 140 and the load determiner 142 can be implemented by one or more computing devices. In some examples, one or more of the one or more computing devices can be local to the HPU 110 and directly coupled to the HPU 110 by wired or wireless communication means, for example, according to any communication standard, including, but not limited to, the Controller Area Network (CAN) bus standard, the Universal Serial Bus standard, the Bluetooth standard, the Wi-Fi Direct standard, or any other type of communication standard. In some examples, one or more of the one or more computing devices may be included in or associated with (e.g., communicatively coupled to) the materials testing machine 130. For example, one or more of the one or more computing devices may be configured to control the materials testing machine to perform a testing process. Such computing devices may be configured to store one or more (e.g., default) pressure set points for each test configuration, for example. In some examples, one or more of the one or more computing devices may be remote computing devices communicatively coupled to the HPU 110 via, for example, a communications network (not shown), such as, for example, a local area network (LAN) or a wide area network (WAN). The communications network may be wired or wireless, or a combination of wired and wireless.

[0133] In examples where the HPU 110 includes a controller 140 , the communications circuitry 126 may be configured to receive an indication of the pressure set point and provide the indication of the pressure set point to the controller 140 .

[0134] In examples where the controller 140 is external to the HPU 110, the communications circuitry 126 may be configured to, for example, receive and provide the pump control signal instructions described above to the pump 114. Additionally or alternatively, in some examples, the communications circuitry 126 may be configured to receive and provide the motor control signals described above from the controller 140 to the motor driver circuitry 122.

[0135] 2-5 are schematic illustrations of example hydraulic power units according to various embodiments of the present disclosure. The example hydraulic power units illustrated in FIGS. 2-5 may correspond to, for example, the HPU 110 illustrated in FIG. 1. Thus, the above description of the HPU 110 is also applicable to the example hydraulic power units illustrated in FIGS. 2-5. The same reference numbers are used for corresponding features in FIGS. 1 and 2-5. For simplicity, the user interface 124 and the communication circuitry 126 are omitted from FIGS. 2-5, however, the example hydraulic power units illustrated in FIGS. 2-5 may optionally include one or both of the user interface 124 and the communication circuitry 126, and may optionally include any other features described with respect to the HPU 110 illustrated in FIG. 1, which may be omitted from the description of FIGS. 2-5.

[0136] It should be understood that the hydraulic power units shown in Figures 2-5, and indeed the HPU 110 shown in Figure 1, are simplified for clarity, and that any hydraulic power unit disclosed herein may include conventional components of a hydraulic power unit not shown in Figures 1-5, including, but not limited to, power feed(s), manifold(s), valve(s), including pressure relief valve(s), pressure compensation valve(s), and any other type of valve, any other conventional hydraulic components, and any combination thereof.

[0137] 2 illustrates generally an exemplary hydraulic power unit (HPU) 200 in accordance with one embodiment of the present disclosure. The HPU 200 is operable to provide pressurized hydraulic fluid at a constant target pressure at its outlet by controlling the flow rate of hydraulic fluid pumped by the HPU 200. As described below, the flow rate may be controlled by controlling the fluid displacement of a pump of the HPU.

[0138] The HPU 200 includes an electric motor 112 , a pump 114 , a reservoir 116 , an outlet 118 , an inlet 120 , a motor driver circuit 122 , and a pressure sensor 210 .

[0139] In the embodiment shown in FIG. 2, the motor driver circuit 122 is configured to provide a power supply 202 to the electric motor 112 via an electrical coupling therebetween.

[0140] In the embodiment shown in FIG. 2, the electric motor 112 is configured to drive the pump 114 via a mechanical connection therebetween, the mechanical connection being indicated by arrow 204 .

[0141] 2, pump 114 is configured to receive hydraulic fluid from reservoir 116 via a fluid connection therebetween, which is indicated by arrow 206. Pump 114 is further configured to pump hydraulic fluid received from reservoir 116 to outlet 118 via a fluid connection therebetween, which is indicated by arrow 208. Inlet 120 is configured to provide hydraulic fluid (e.g., received from a materials testing device, such as materials testing device 130) to reservoir 116 via a fluid connection therebetween, as indicated by arrow 214.

[0142] 2, electric motor 112 is an AC electric motor configured to operate at a substantially fixed (e.g., substantially constant) rotational speed, and pump 114 is operable as a pressure compensated variable displacement pump having a fixed pressure set point. Pressure sensor 210 is configured to measure the output pressure of HPU 200 and provide an indication of the measured output pressure to pump 114, as indicated by arrow 212. Pump 114 is configured to control its fluid displacement based on its fixed pressure set point and the received measured pressure to substantially maintain the output pressure at the pressure set point, according to examples disclosed herein.

[0143] Advantageously, in situations where the flow demand at a pressure set point is particularly low, the fluid displacement of pump 114 can be controlled to a correspondingly low fluid displacement value, thus reducing the load demand on the motor, thereby reducing the power consumption of the motor and the power consumption of HPU 200. Furthermore, because the fluid displacement of pump 114, and therefore the flow rate provided by HPU 200 at the pressure set point, can be adjusted to meet the flow demand, there may be no need to vent excess hydraulic fluid flow, for example through a relief valve, which may have associated cooling requirements with associated energy costs.

[0144] The motor driver circuit 122 includes an electric inverter as described in connection with FIG. 1 configured to control an operating point of the electric motor 112 by controlling one or more parameters of the (AC) electrical power supply provided to the electric motor 112. In the embodiment shown in FIG. 2, the motor driver circuit 122 with an electric inverter is configured to control one or more parameters of the AC electrical power supply such that an operating efficiency of the electric motor 112 is altered to maintain an operating point, according to examples disclosed herein. For example, the motor driver circuit 122 with an electric inverter may be configured to control one or more parameters of the AC electrical power supply provided to the electric motor 112 to maintain an operating point, e.g., reduce input power, thereby increasing an operating efficiency of the electric motor 112 relative to the operating point. Thus, the HPU 200 can provide an energy-efficient HPU.

[0145] Although pressure sensor 210 and indication of measured output pressure 212 are shown as being external to pump 114, this is by way of example only and the disclosure is not so limited. In other examples, pump 114 can include pressure sensor 210.

[0146] FIG. 3 illustrates a schematic of an exemplary hydraulic power unit (HPU) 300 according to one embodiment of the present disclosure.

[0147] The HPU 300 includes an electric motor 112 , a pump 114 , a reservoir 116 , an outlet 118 , an inlet 120 , a motor driver circuit 122 , a pressure sensor 310 , and a controller 140 .

[0148] The HPU 300 is operable to provide pressurized hydraulic fluid at its outlet at a variable target pressure by controlling the flow rate of hydraulic fluid pumped by the HPU 300. As described below, the flow rate can be controlled by controlling the rotational speed of the electric motor 112 of the HPU 300.

[0149] In the embodiment shown in FIG. 3, the electric motor 112 is configured to operate at variable speeds and the pump 114 is operable as a positive displacement pump having a substantially fixed fluid displacement volume.

[0150] In the embodiment shown in FIG. 3, the motor driver circuit 122 is configured to provide a power supply 302 to the electric motor 112 via an electrical coupling therebetween.

[0151] In the embodiment shown in FIG. 3, the electric motor 112 is configured to drive the pump 114 via a mechanical connection therebetween, as indicated by arrow 304.

[0152] 3, pump 114 is configured to receive hydraulic fluid from reservoir 116 via a fluid connection therebetween, as indicated by arrow 306. Pump 114 is further configured to pump hydraulic fluid received from reservoir 116 to outlet 118 via a fluid connection therebetween, as indicated by arrow 308. Inlet 120 is configured to provide hydraulic fluid (e.g., received from a materials testing device, such as materials testing device 130) to reservoir 116 via a fluid connection therebetween, as indicated by arrow 314.

[0153] In the embodiment shown in FIG. 3, the controller 140 is configured to control the rotational speed of the electric motor 112 to control the output pressure of the HPU 300 based on a pressure set point, such as a first pressure set point for performing a first material testing process, a second pressure set point for performing a second material testing process, or any other pressure set point (e.g., to maintain the output pressure of the HPU 300 at a target pressure, where the target pressure is based on the pressure set point, e.g., the target pressure is greater than or equal to the pressure set point).

[0154] 3, the controller 140 includes an input 316 configured to receive an instruction 318 of a pressure set point (e.g., a first pressure set point for performing a first material testing process, or, e.g., a second pressure set point for performing a second material testing process). The instruction 318 may be received, for example, according to any of the examples disclosed herein.

[0155] 3, the controller 140 has an output 320 configured to provide a motor control signal 322 to the motor driver circuit 122, where the output 320 of the controller 140 is electrically coupled to an input of the motor driver circuit 122 configured to receive the motor control signal. The motor control signal 322 may be operable to control the electric motor 112, for example, according to any of the examples disclosed herein.

[0156] With respect to the embodiment shown in FIG. 3, in some examples, as described in relation to the embodiment shown in FIG. 1, the motor driver circuit 122 may comprise a control means (not shown) operable to receive an indication of a pressure set point (e.g., a first pressure set point or a second pressure set point, etc.) and control the output pressure of the HPU 300 based on the pressure set point by controlling the rotational speed of the electric motor 112. In these examples, the motor control signal 322 may include an indication of a pressure set point, e.g., a first pressure set point or a second pressure set point, etc. In other examples, the controller 140 may be configured to directly control the rotational speed of the electric motor 112 to control the output pressure of the HPU 300 based on the pressure set point (e.g., a first pressure set point or a second pressure set point, etc.). In these examples, the motor control signal 322 may include an indication of one or more parameters of the power supply, and the motor driver circuit 122 may be configured to control the one or more parameters of the power supply in accordance with the motor control signal 322.

[0157] 3, the HPU 300 is configured to utilize closed loop control to maintain the output pressure of the HPU 300. The pressure sensor 310 is configured to measure the output pressure of the HPU 300 and provide an indication of the measured output pressure as feedback to control the rotational speed of the electric motor 112. In examples where the motor driver circuit 122 comprises the control means described above, the pressure sensor can be configured to provide an indication of the measured output pressure to the motor driver circuit 122, as indicated by arrow 324. In examples where the controller 140 is configured to directly control the rotational speed of the electric motor 112, the pressure sensor can be configured to provide an indication of the measured output pressure to an input 326 of the controller 140, as indicated by arrow 328.

[0158] Advantageously, HPU 300 provides an HPU operable to adjust its output pressure according to the pressure requirements of a materials testing process, thereby enabling an HPU with reduced power consumption.

[0159] 3, in some examples, the electric motor 112 can include an AC electric motor and the motor driver circuit 122 can include an electric inverter according to examples disclosed herein. In these examples, the motor driver circuit 122 including the electric inverter can be configured to control the operating point of the electric motor 112 by controlling one or more parameters of the (AC) power supply 302 such that the operating efficiency of the electric motor 112 is altered to maintain the operating point, according to any examples disclosed herein. Advantageously, this can enable the HPU 300 to operate even more efficiently.

[0160] FIG. 4 illustrates a schematic of an exemplary hydraulic power unit (HPU) 400 according to one embodiment of the present disclosure.

[0161] The HPU 400 includes an electric motor 112, a pump 114, a reservoir 116, an outlet 118, an inlet 120, a pressure sensor 410, and a controller 140. Optionally, in some examples, the HPU 400 includes a motor driver circuit 122.

[0162] The HPU 400 is operable to provide pressurized hydraulic fluid at its outlet at a variable target pressure by controlling the flow rate of hydraulic fluid pumped by the HPU 400. As described below, the flow rate can be controlled by controlling the fluid displacement of the pump 114 of the HPU 400.

[0163] In the embodiment shown in FIG. 4, the electric motor 112 is configured to drive the pump 114 via a mechanical connection therebetween, as indicated by arrow 404.

[0164] 4, pump 114 is configured to receive hydraulic fluid from reservoir 116 via a fluid connection therebetween, as indicated by arrow 406. Pump 114 is further configured to pump hydraulic fluid received from reservoir 116 to outlet 118 via a fluid connection therebetween, as indicated by arrow 408. Inlet 120 is configured to provide hydraulic fluid (e.g., received from a materials testing device, such as materials testing device 130) to reservoir 116 via a fluid connection therebetween, as indicated by arrow 414.

[0165] In the embodiment shown in FIG. 4, electric motor 112 includes any type of electric motor, including, for example, any type of electric motor disclosed herein or any other type of electric motor.

[0166] In the embodiment shown in FIG. 4, the electric motor 112 is configured to operate at a substantially fixed speed, and the pump 114 is operable as a pressure-compensated variable displacement pump having an adjustable pressure set point, according to examples disclosed herein.

[0167] 4, the controller 140 is configured to control the output pressure of the HPU 400 based on a pressure setpoint (e.g., maintain the output pressure of the HPU 400 at a target pressure, where the target pressure is based on a pressure setpoint, e.g., the target pressure is equal to or greater than the pressure setpoint), such as, for example, a first pressure setpoint for performing a first material testing process, a second pressure setpoint for performing a second material testing process, or any other pressure setpoint. In some examples, the controller 140 is configured to control the fluid displacement of the pump 114 based on the pressure setpoint for performing the first material testing process.

[0168] 4, the controller 140 includes an input 416 configured to receive an instruction 418 of a pressure set point (e.g., a first pressure set point for performing a first material testing process, or, e.g., a second pressure set point for performing a second material testing process). The instruction 418 may be received, for example, according to any example disclosed herein.

[0169] 4, the controller 140 includes an output 420 configured to provide a pump control signal 422 to the pump 114, the output 420 of the controller 140 being electrically coupled to an input of the pump 114 configured to receive the pump control signal 422. The pump control signal 422 may be operable to control the pump 114, for example, according to any of the examples disclosed herein.

[0170] With respect to the embodiment shown in FIG. 4, in some examples, as described in relation to the embodiment shown in FIG. 1, the pump 114 may include a pressure compensation control means (not shown) operable to receive an indication of a pressure set point (e.g., a first pressure set point or a second pressure set point, etc.) and control the output pressure of the HPU 400 based on the pressure set point by controlling the fluid displacement of the pump 114. In these examples, the pump signal 422 may include an indication of a pressure set point, e.g., a first pressure set point or a second pressure set point, etc. In other examples, the controller 140 may be configured to directly control the fluid displacement of the pump 114 to control the output pressure of the HPU 400 based on the pressure set point (e.g., the first pressure set point or the second pressure set point, etc.). In these examples, the pump control signal 422 may include an indication of a fluid displacement of the pump 114, and the pump 114 may be configured to control its fluid displacement in accordance with the pump control signal 422.

[0171] 4, the HPU 400 is configured to utilize closed loop control to maintain the output pressure of the HPU 400. The pressure sensor 410 is configured to measure the output pressure of the HPU 400 and provide an indication of the measured output pressure as feedback to control the fluid displacement of the pump 114. In examples where the pump 114 includes the pressure compensation control means described above, the pressure sensor 410 can be configured to provide an indication of the measured output pressure to the pump 114, as indicated by arrow 424. In examples where the controller 140 is configured to directly control the fluid displacement of the pump, the pressure sensor 410 can be configured to provide an indication of the measured output pressure to an input 426 of the controller 140, as indicated by arrow 428.

[0172] Advantageously, HPU 400 provides an HPU operable to adjust its output pressure according to the pressure requirements of a materials testing process, thereby enabling an HPU with reduced power consumption.

[0173] 4, in some examples, the electric motor 112 can include an AC electric motor, and the HPU 400 can further include a motor driver circuit 122 with an electrical inverter configured to provide the (AC) power supply 402 to the electric motor 112 via an electrical coupling therebetween. In these examples, the motor driver circuit 122 with an electrical inverter can be configured to control an operating point of the electric motor 112 by controlling one or more parameters of the (AC) power supply such that an operating efficiency of the electric motor 112 is altered to maintain the operating point, according to any examples disclosed herein. Advantageously, this can enable the HPU 400 to operate even more efficiently.

[0174] FIG. 5 illustrates a schematic of an exemplary hydraulic power unit (HPU) 500 according to one embodiment of the present disclosure.

[0175] The HPU 500 includes an electric motor 112 , a pump 114 , a reservoir 116 , an outlet 118 , an inlet 120 , a motor driver circuit 122 , a pressure sensor 510 , and a controller 140 .

[0176] The HPU 500 is operable to provide pressurized hydraulic fluid at its outlet at a variable target pressure by controlling the flow rate of hydraulic fluid pumped by the HPU 500. As described below, the flow rate can be controlled by controlling both the rotational speed of the electric motor 112 of the HPU 500 and the fluid displacement of the pump 114. One or both of the fluid displacement of the pump 114 and the rotational speed of the electric motor 122 can be controlled in response to predetermined characterization data such that the combined operating efficiency of the electric motor and pump is controlled.

[0177] In the embodiment shown in FIG. 5, in accordance with examples disclosed herein, the electric motor is configured to operate at variable speeds and the pump 114 is operable as a pressure compensated variable displacement pump with an adjustable pressure set point.

[0178] In the embodiment shown in FIG. 5, the motor driver circuit 122 is configured to provide a power supply 502 to the electric motor 112 via an electrical coupling therebetween.

[0179] In the embodiment shown in FIG. 5, the electric motor 112 is configured to drive the pump 114 via a mechanical connection therebetween, as indicated by arrow 504.

[0180] 5, pump 114 is configured to receive hydraulic fluid from reservoir 116 via a fluid connection therebetween, as indicated by arrow 506. Pump 114 is further configured to pump hydraulic fluid received from reservoir 116 to outlet 118 via a fluid connection therebetween, as indicated by arrow 508. Inlet 120 is configured to provide hydraulic fluid (e.g., received from a materials testing device, such as materials testing device 130) to reservoir 116 via a fluid connection therebetween, as indicated by arrow 514.

[0181] 5, the controller 140 is configured to control both the rotational speed of the electric motor 112 and the fluid displacement of the pump 114 to control the output pressure of the HPU 500 based on a pressure setpoint (e.g., maintain the output pressure of the HPU 500 at a target pressure, where the target pressure is based on the pressure setpoint, e.g., the target pressure is equal to or greater than the pressure setpoint), such as a first pressure setting for performing a first material testing process, a second pressure setpoint for performing a second material testing process, or any other pressure setpoint. In some examples, the controller 140 is configured to control both the rotational speed of the electric motor 112 and the fluid displacement of the pump 114 based on the pressure setpoint.

[0182] 5, the controller 140 includes an input 516 configured to receive an instruction 518 of a pressure set point (e.g., a first pressure set point for performing a first material testing process, or, e.g., a second pressure set point for performing a second material testing process). The instruction 518 may be received, for example, according to any of the examples disclosed herein.

[0183] 5, the controller 140 includes a first output 520 configured to provide a motor control signal 522 to the motor driver circuit 122, where the first output 520 of the controller 140 is electrically coupled to an input of the motor driver circuit 122. The motor control signal 522 may be operable to control the electric motor 112, for example, according to any of the examples disclosed herein.

[0184] 5, the controller 140 includes a second output 523 configured to provide a pump control signal 525 to the pump 114, the output 523 of the controller 140 being electrically coupled to an input of the pump 114. The pump control signal 525 may be operable to control the pump 114, for example, according to any of the examples disclosed herein.

[0185] With respect to the embodiment shown in FIG. 5, in some examples, as described in relation to the embodiment shown in FIG. 1, the motor driver circuit 122 may comprise a control means (not shown) operable to receive an indication of a pressure set point (e.g., a first pressure set point or a second pressure set point, etc.) and control the output pressure of the HPU 500 based on the pressure set point by controlling the rotational speed of the electric motor 112. In these examples, the motor control signal 522 may include an indication of a pressure set point, e.g., a first pressure set point or a second pressure set point, etc. In other examples, the controller 140 may be configured to directly control the rotational speed of the electric motor 112 to control the output pressure of the HPU 500 based on the pressure set point (e.g., a first pressure set point or a second pressure set point, etc.). In these examples, the motor control signal 522 may include an indication of one or more parameters of the power supply, and the motor driver circuit 122 may be configured to control the one or more parameters of the power supply in accordance with the motor control signal 522.

[0186] With respect to the embodiment shown in FIG. 5, in some examples, as described in relation to the embodiment shown in FIG. 1, the pump 114 may include a pressure compensation control means (not shown) operable to receive an indication of a pressure set point (e.g., a first pressure set point or a second pressure set point, etc.) and control the output pressure of the HPU 500 based on the pressure set point by controlling the fluid displacement of the pump 114. In these examples, the pump control signal 525 may include an indication of a pressure set point, e.g., a first pressure set point or a second pressure set point, etc. In other examples, the controller 140 may be configured to directly control the fluid displacement of the pump 114 to control the output pressure of the HPU 500 based on the pressure set point (e.g., the first pressure set point or the second pressure set point, etc.). In these examples, the pump control signal 525 may include an indication of a fluid displacement of the pump 114, and the pump 114 may be configured to control its fluid displacement in accordance with the pump control signal 525.

[0187] 5, the HPU 500 is configured to utilize closed-loop control to maintain the output pressure of the HPU 500. A pressure sensor 510 is configured to measure the output pressure of the HPU 500 and provide an indication of the measured output pressure as feedback to control both the rotational speed of the electric motor 112 and the fluid displacement of the pump 114.

[0188] In examples in which the motor driver circuit 122 comprises the control means described above, the pressure sensor 510 may be configured to provide an indication of the measured output pressure to the motor driver circuit 122, as indicated by arrow 530.

[0189] In examples in which the pump 114 is equipped with the pressure compensation control means discussed above, the pressure sensor 510 may be configured to provide an indication of the measured output pressure to the pump 114 , as indicated by arrow 532 .

[0190] In an example in which the controller 140 is configured to directly control one or both of the rotational speed of the electric motor 112 and the fluid displacement volume of the pump 114, the pressure sensor 510 can be configured to provide an indication of the measured output pressure to an input 532 of the controller 140, as indicated by arrow 534.

[0191] Advantageously, the HPU 500 provides an HPU operable to adjust its output pressure according to the pressure requirements of a materials testing process, thereby enabling an HPU with reduced power consumption.

[0192] In some examples, controller 140 may be configured to control both the rotational speed of electric motor 112 (e.g., via motor control signal 522) and the fluid displacement of pump 114 (e.g., via pump control signal 525) to control the output pressure of HPU 110 based on a pressure set point, and controller 140 is configured to control one or both of the fluid displacement of pump 114 and the rotational speed of electric motor 112 in dependence on predetermined characterization data such that the combined operating efficiency of electric motor 112 and pump 114 is controlled according to any examples disclosed herein. Advantageously, this may enable HPU 500 to operate even more efficiently.

[0193] 5, in some examples, the electric motor 112 can include an AC electric motor and the motor driver circuitry 122 can include an electric inverter configured to provide an (AC) power supply 502 to the electric motor 112. In these examples, the motor driver circuitry 122 including the electric inverter can be configured to control the operating point of the electric motor 112 by controlling one or more parameters of the (AC) power supply such that the operating efficiency of the electric motor 112 is altered to maintain the operating point, according to any examples disclosed herein. Advantageously, this can further improve the efficiency of the HPU 500.

[0194] 6 illustrates a schematic diagram of an apparatus 600 in accordance with various embodiments of the present disclosure. In some examples, the apparatus 600 may correspond to, for example, a controller, such as, for example, the controller 140. In some examples, the apparatus 600 may correspond to the load determiner 142.

[0195] As shown in Fig. 6, the device 600 may be implemented by a processor 610 and a memory 620 including a computer program 622 including computer program instructions 624. The device 600 may include an output interface 630, which may be included in or operably coupled to the processor 610, via which data and / or commands in the form of control signals are output by the processor 610. The device 600 may include an input interface 640, which may be included in or operably coupled to the processor 610, via which data and / or commands are input to the processor 610. An implementation of the device 600 may be hardware only (circuitry), may have certain aspects in software including firmware only, or may be a combination of hardware and software (including firmware). The computer program 622 may be stored in a (e.g. non-transitory) computer readable storage medium (disk, memory, etc.). The computer program 622 may be computer software configured, when executed, i.e. by the processor 610, to perform a method in accordance with the methods described below in relation to one or more of Figures 7 and 8.

[0196] 7 illustrates an example flowchart 700 that is schematic for controlling a hydraulic power unit according to an embodiment of the present disclosure. The hydraulic power unit may include, for example, any one of hydraulic power unit 110, hydraulic power unit 300, hydraulic power unit 400, and hydraulic power unit 500. Flowchart 700 may be implemented by a controller operable to control the hydraulic power unit, such as, for example, controller 140.

[0197] At block 710, the pressure of the pressurized hydraulic fluid provided to the materials testing machine is controlled based on a first pressure set point to perform the first materials testing process. Controlling the pressurized hydraulic fluid based on the first pressure set point may be according to any example disclosed herein.

[0198] An indication of a second pressure set point for a second material testing process performed by the material testing machine is received at block 720. Receiving the indication of the second pressure set point may be according to any example disclosed herein.

[0199] At block 730, the pressure of the pressurized hydraulic fluid provided to the materials testing machine is controlled based on a second pressure set point. Controlling the pressurized hydraulic fluid based on the second pressure set point may be according to any example disclosed herein.

[0200] FIG. 8 shows an exemplary flow chart that generally illustrates a method according to the present disclosure.

[0201] At block 810, an indication of a test configuration of a test process to be performed by a material testing machine is obtained, the material testing machine being configured to receive pressurized hydraulic fluid from a hydraulic power unit (HPU). The material testing machine can correspond to, for example, material testing machine 130 or any other material testing machine. The hydraulic power unit can include, for example, any one of hydraulic power unit 110, hydraulic power unit 300, hydraulic power unit 400, and hydraulic power unit 500. The material testing process can correspond to any material testing process, including, for example, any material testing process disclosed herein. The indication of the test configuration can be obtained according to any example disclosed herein.

[0202] At block 820, a load requirement of the testing process may be determined based on the received indication of the test configuration. The load requirement may be determined according to any example disclosed herein.

[0203] At block 830, pressure set point instructions based on the determined load demand are provided to a controller, which is configured to control the pressure of the pressurized hydraulic fluid to perform the materials testing process. The controller may correspond to, for example, controller 140. The instructions may be provided to the controller according to any example disclosed herein.

[0204] It will be understood that embodiments of the present invention can be realized in the form of hardware, software, or a combination of hardware and software. Any such software can be stored in the form of volatile or non-volatile storage, such as a storage device such as a ROM, whether erasable or not, or rewritable or not, or in the form of memory, such as a RAM, memory chip, device, or integrated circuit, or on an optically or magnetically readable medium, such as a CD, DVD, magnetic disk, or magnetic tape. It will be understood that such storage devices and media are embodiments of machine-readable storage suitable for storing one or more programs that, when executed, implement embodiments of the present invention. Thus, embodiments provide a program including code implementing a system or method as claimed in any preceding claim, and a machine-readable storage device storing such a program. Still further, embodiments of the present invention can be transmitted electronically over any medium, such as a communication signal carried over a wired or wireless connection, and embodiments include that as appropriate.

[0205] 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.

[0206] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), unless expressly stated otherwise, may be replaced by alternative features serving the same, equivalent or similar purpose. Thus, unless expressly stated otherwise, each feature disclosed is only an example of a generic series of equivalent or similar features.

[0207] The present invention is not limited to the details of any of the above-mentioned embodiments. The present invention extends to any novel one or any novel combination of features disclosed in this specification (including any accompanying claims, abstract and drawings), or any novel one or any novel combination of steps of any method or process so disclosed. The claims should not be construed to cover merely the above-mentioned embodiments, but also any embodiment that falls within the scope of the claims.

Claims

1. 1. A method of controlling a hydraulic power unit (HPU) that provides pressurized hydraulic fluid to a materials testing apparatus, the HPU having an electric motor and a pump, the method comprising: controlling a pressure of the pressurized hydraulic fluid based on a first pressure set point to perform a first material testing process; receiving an indication of a second pressure set point for a second material testing process performed by the material testing machine; controlling the pressure of the pressurized hydraulic fluid based on the second pressure set point to perform the second material testing process; A method comprising:

2. 1. A method comprising: obtaining an indication of a test configuration for a materials testing process to be performed by a materials testing machine, the materials testing machine being configured to receive pressurized hydraulic fluid from a hydraulic power unit (HPU); determining a load requirement for the materials testing process based on the received indication of the test configuration; providing a pressure set point indication to a controller based on the determined load demand, the controller being configured to control a pressure of the pressurized hydraulic fluid to perform the material testing process; A method comprising:

3. 1. A controller for controlling a hydraulic power unit (HPU) having an electric motor and a pump, the HPU configured to provide pressurized hydraulic fluid to a materials testing device, the controller comprising: controlling a pressure of the pressurized hydraulic fluid based on a first pressure set point to perform a first material testing process; receiving an indication of a second pressure set point for a second material testing process to be performed by the material testing machine; controlling the pressure of the pressurized hydraulic fluid based on the second pressure set point to perform the second material testing process; The controller is configured as follows:

4. 1. An apparatus comprising: obtaining test configuration instructions for a materials testing process to be performed by the materials testing device; determining a load requirement for the materials testing process based on the obtained indication of the test configuration; providing a pressure set point indication to a controller based on the determined load demand; and the controller is configured to control the pressure of the pressurized hydraulic fluid to perform the testing process. Device.

Images