Systems, Methods and Non-Transitory Computer-Readable Media for Active Hydraulic System Warmup

Some example embodiments provide systems, methods, and non-transitory computer-readable media for warming oil of a hydraulic system by pumping the oil though open center valves of the hydraulic system.

Heavy machines including, for example, dozers, loaders, excavators, motor graders, etc. typically comprise a number of hydraulic actuators to perform various functions. Actuators are fluidly connected to a pump on the machine that provides pressurized hydraulic oil to chambers within the actuators. As the pressurized hydraulic oil moves into or through the chambers, the pressure of the oil acts on hydraulic surfaces of the chambers to affect movement of the actuator and a connected implement (e.g., a work tool). When the pressurized oil is drained from the chambers it is returned to a low pressure tank on the machine.

Some example embodiments provide improved systems, methods, and non-transitory computer-readable media that enables warming of hydraulic oil using existing open center valves of a hydraulic system.

Some example embodiments provide a system including a pump, a valve including an open center passage, the valve being configured to return a hydraulic oil flow received from the pump to a hydraulic reservoir through the open center passage when the valve is in a first position, and pass the hydraulic oil flow to an actuator when the valve is in a work position, and processing circuitry configured to cause the hydraulic system to determine whether a current temperature of hydraulic oil is less than or equal to a target temperature, cause a position of the valve to be set to the first position in response to determining that the current temperature of the hydraulic oil is less than or equal to the target temperature, and cause the pump to flow the hydraulic oil to the valve.

Some example embodiments provide a method including determining whether a current temperature of hydraulic oil is less than or equal to a target temperature, causing a position of a valve to be set to a first position in response to determining that the current temperature of the hydraulic oil is less than or equal to the target temperature, the valve including an open center passage, and the valve being configured to return a hydraulic oil flow received from a pump to a hydraulic reservoir through the open center passage when the valve is in the first position, and pass the hydraulic oil flow to an actuator when the valve is in a work position, and causing the pump to flow the hydraulic oil to the valve.

Some example embodiments provide a non-transitory computer-readable medium storing instructions that, when executed by at least one processor, cause the at least one processor to perform a method, the method includes determining whether a current temperature of hydraulic oil is less than or equal to a target temperature, causing a position of a valve to be set to a first position in response to determining that the current temperature of the hydraulic oil is less than or equal to the target temperature, the valve including an open center passage, and the valve being configured to return a hydraulic oil flow received from a pump to a hydraulic reservoir through the open center passage when the valve is in the first position, and pass the hydraulic oil flow to an actuator when the valve is in a work position, and causing the pump to flow the hydraulic oil to the valve.

The performance and/or response of hydraulic systems vary according to a temperature of hydraulic oil used in the hydraulic systems. For example, the performance and/or response of the hydraulic systems may be reduced when the temperature of the hydraulic oil falls below a target temperature. This is particularly challenging in Electro-Hydraulic (EH) systems, where pilot passageways are restricted and susceptible to response differences with varying oil viscosities.

Existing devices and methods for warming hydraulic oil involve adding components to the hydraulic systems such as, additional valves, flushing circuits, throttles, etc. Such additional and/or specialized components increase the complexity, manufacturing costs and/or physical size of the hydraulic systems. However, some example embodiments provide improved devices and methods for warming hydraulic oil as discussed further below.

illustrates a work vehicle, in accordance with some example embodiments.

Referring to, depicted is a left side view of a work vehicle. The work vehicleis illustrated as a hydraulic excavator, including a chassis or frame, and traction members (e.g., crawler tracks) for supporting and propelling the framealong a surface. In some example embodiments, the frameincludes a platform that is rotatable relative to the tracksabout a vertical axis. The excavatormay further include an operator caband/or a boomsupported on the frame. A tool or work attachment (e.g., a bucket) may be coupled to an end of the boom. The excavatormay also include a drive system having a prime mover or engine (not shown), motors (not shown) for driving the tracks, and/or motors (not shown) for pivoting the platform about the axis. In some example embodiments, the motors may be hydraulic motors. Although the work vehicleis illustrated and described as the excavator, it is understood that the work vehiclemay have a different form, such as a loader, a dozer, a motor grader, a scraper, or another type of construction, mining, agricultural, or utility machine. Also, although the work attachment is illustrated and described as the bucket, it is understood that the work attachment may have a different form, such as an auger, a breaker, a ripper, a grapple, or some other type of attachment for digging, breaking, handling, carrying, dumping or otherwise engaging dirt or other material. In addition, the work attachment may be detachable from the boomto permit another type of work attachment to be coupled to the boom.

In the illustrated example, the boomincludes a primary member or hoist portionpivotably coupled to the frame, and an arm or stick portionpivotably coupled to an end of the hoist portion. The work attachmentis pivotably coupled to an end of the stick portion. The excavatormay include actuators such as hydraulic cylindersfor actuating or moving the bucket, the hoist portion, and the stick portionrelative to one another and relative to the frame. For example, the actuators may include a first actuatorfor actuating or moving the hoist portion, a second actuatorfor actuating or moving the stick portionand a third actuatorfor actuating or moving the bucket. According to some example embodiments, the actuators, boomand/or traction members discussed in connection withare merely examples and some example embodiments are not limited thereto. For example, according to some example embodiments, the work vehiclemay include different actuators, a different boomand/or different traction members from those discussed in connection with. Also, one or more components discussed in connection withmay be omitted, and/or one or more other components added, according to some example embodiments.

illustrates an Electro-Hydraulic (EH) system according to some example embodiments.

Referring to, an EH systemmay include a pump, a valve, an actuatorand/or a hydraulic reservoir. According to some example embodiments, the EH systemmay include a pressure sensor(e.g., a pressure transducer) positioned, for example, between the pumpand the valve, but some example embodiments are not limited thereto. The pumpmay be an EH-controlled pump. For example, the pumpmay be an Electronic Displacement Control (EDC) pump, and a flow rate of the pumpmay be controlled using a first EH solenoid. Each of the pump, the valve, the actuatorand the hydraulic reservoir may be connected through hydraulic lines,,andcarrying hydraulic oil. Althoughillustrates only a single pump, a single valveand a single actuator, some example embodiments are not limited thereto. According to some example embodiments, the EH systemmay include an additional pump(s), an additional valve(s)and/or an additional actuator(s). According to some example embodiments, the actuatormay be used to implement each of the first actuator, the second actuatorand the third actuatordiscussed in connection with. According to some example embodiments, the EH systemmay be partially or entirely included on the work vehicle, but some example embodiments are not limited thereto and at least one or more elements of the EH systemmay be external to the work vehicle.

A position of the valvemay be controlled using a second EH solenoid. In scenarios in which the EH systemincludes a plurality of valves, a respective position of each of the plurality of valvesmay be controlled using a corresponding second EH solenoid. The valvemay be set to a plurality of different positions including at least a neutral position and one or more work positions. When the valveis set to the neutral position, the valvedisconnects the actuatorfrom the flow of hydraulic oil pumped by the pumpsuch that the actuatordoes not move the boom(e.g., any among the first actuatoror the hoist portion, the second actuatoror the stick portion, and/or the third actuatoror the bucket). Specifically, the valveincludes an open center passage, and when the valveis set to the neutral position the flow of hydraulic oil enters the open center passagethrough a first hydraulic lineand returns to the hydraulic reservoirthrough a second hydraulic lineafter exiting the open center passage. Alternatively, when the valveis set to a work position, the flow of the hydraulic oil passes through the valveto the actuatorvia one among the third or fourth hydraulic linesor, enables the actuatorto move the boom(e.g., any among the first actuatoror the hoist portion, the second actuatoror the stick portion, and/or the third actuatoror the bucket), and returns via the other among the third or fourth hydraulic linesor. In scenarios in which the EH systemincludes a plurality of valves, each of the plurality of valvesmay be set to a respective position among the neutral position or the one or more work positions. According to some example embodiments, every respective valveamong a plurality of valvesmay be configured to () return a hydraulic oil flow to the hydraulic reservoir, and/or () pass the hydraulic oil flow to a corresponding actuator, based on a position of the of the respective valve(e.g., the neutral position or the one or more work positions), but some example embodiments are not limited thereto.

illustrate a valve set to different positions according to some example embodiments.

Referring to, the valveis illustrated as being set to the neutral position. In the neutral position, an entry portand an exit portof the open center passageare aligned to match the first hydraulic lineand the second hydraulic line, respectively. Accordingly, in the neutral position hydraulic oil flow restriction at the connections between the entry portwith the first hydraulic line, and between the exit portand the second hydraulic line, are minimized or relatively low (particularly as compared to the intermediate position discussed below).

Referring to, the valveis illustrated as being set to a work position. In the work position, an entry portand an exit portof a work passageare aligned to match the first hydraulic lineand the second hydraulic line, respectively. Accordingly, in the work position hydraulic oil flow restriction at the connections between the entry portwith the first hydraulic line, and between the exit portand the second hydraulic line, are minimized or relatively low (particularly as compared to the intermediate position discussed below).

Referring back to, some example embodiments provide improved devices and methods for warming hydraulic oil. For example, by setting the valveto the neutral position, the open center passagecreates a restriction to the flow of the hydraulic oil. This restriction increases the oil pressure at an outlet of the pump, and thereby increases a pressure drop across an inlet and an outlet of the open center passagethat causes the hydraulic oil to warm. Accordingly, the improved devices and methods enable warming of the hydraulic oil without the incorporation of additional and/or specialized components (e.g., additional valves, flushing circuits, throttles, etc.). Therefore, the improved devices and methods overcome the deficiencies of the existing devices and methods to at least reduce the complexity, manufacturing costs and/or physical size of hydraulic systems relative to those of the existing devices and methods. According to some example embodiments, in scenarios in which the EH systemincludes a plurality of valves, hydraulic oil warming may be performed by setting only a single one, two or more, or all among the plurality of valvesto the neutral position.

According to some example embodiments, the second EH solenoidmay set the valveto an intermediate position during a warming operation. For example, the intermediate position may be a position between the neutral position and a work position. When the valvetransitions from the neutral position to a work position, the center passage begins to be restricted before the hydraulic oil is able to pass through the valveinto the third or fourth hydraulic lineor. This position at which the area of the open center passageis reduced, causing the above-mentioned restriction, without the hydraulic oil being able to pass through the valveinto the third or fourth hydraulic lineormay be referred to herein as the intermediate position. In the intermediate position, the amount of restriction across the open center passageis increases relative to that provided in the neutral position, and thus, the pressure drop across the open center passagein the intermediate position is likewise increased relative to that provided in the neutral position. This increase in the pressure drop across the open center passagecauses the hydraulic oil to warm faster than when the valveis in the neutral position. Accordingly, in examples in which the valveis set to the intermediate position during a warming operation, faster hydraulic oil warming is enabled without the incorporation of additional and/or specialized components (e.g., additional valves, flushing circuits, throttles, etc.). According to some example embodiments, in scenarios in which the EH systemincludes a plurality of valves, hydraulic oil warming may be performed by setting only a single one, two or more, or all among the plurality of valvesto the intermediate position.

Referring to, the valveis illustrated as being set to the intermediate position. In the neutral position, the entry portand the exit portof the open center passageare shifted in the direction of the work passagerelative to the positioning of the neutral position. Accordingly, the entry portand the exit portare only partly aligned with the first hydraulic lineand the second hydraulic line, respectively. In the intermediate position, the path of the hydraulic oil flow is further restricted entry portand the exit portdue to the partial alignment with the first hydraulic lineand the second hydraulic line, respectively. This further restriction increases the pressure drop across the open center passagerelative to that provided in the neutral position.

According to some example embodiments, additionally or alternatively to performing hydraulic oil warming by setting the position of the valveto one of the neutral position or the intermediate position, hydraulic oil warming may be performed by setting a flow rate of the pump. An amount of thermal energy transferred to the hydraulic oil corresponds to both the pressure drop across the valveand the flow rate of the hydraulic oil. Accordingly, hydraulic oil warming may be performed by increasing the flow rate of the pumpin addition to, or as an alternative to, the setting of the position of the valve to the neutral position or the intermediate position. Accordingly, in some example embodiments, hydraulic oil warming is enabled by controlling a flow rate of the pumpwithout the incorporation of additional and/or specialized components (e.g., additional valves, flushing circuits, throttles, etc.).

As noted above, the intermediate position of the valveis a position at which the area of the open center passageis reduced without the hydraulic oil being able to pass through the valveinto the third or fourth hydraulic lineor. However, various implementations of the EH systemare possible, and in implementations in which setting the valveto the intermediate position without the hydraulic oil being able to pass through the valveinto the third or fourth hydraulic lineoris impossible or difficult, additional solutions may be provided to enable the warming operation.

According to some example embodiments, for example, prior to setting the valveto the intermediate position, the boom(e.g., any among the first actuatoror the hoist portion, the second actuatoror the stick portion, and/or the third actuatoror the bucket) may be placed against a stop rendering movement of the boomimpossible or difficult. In so doing, the hydraulic oil flow would be forced across the open center passageresulting in the pressure drop without risking movement of the boom. Additionally or alternatively, according to some example embodiments, a dedicated valvethat is not configured to pass hydraulic oil to an actuatormay be used to perform the warming operation using the open center passageof the dedicated valve(e.g., set to either the neutral position or the intermediate position). Additionally or alternatively, according to some example embodiments, the valvemay be manufactured such that a range of positions, in which hydraulic oil flow across the open center passageis restricted without the hydraulic oil being able to pass through the valveinto the third or fourth hydraulic lineor, is increased.

illustrates a control device for controlling the EH system of, according to some example embodiments. Referring to, a control devicemay include a processor, a memory, a communication device, a temperature sensor, a user interface (UI)and/or a movement detector. The processormay control overall operation of the control deviceand may be implemented using processing circuitry. The term ‘processing circuitry,’ as used in the present disclosure, may refer to, for example, hardware including logic circuits; a hardware/software combination such as a processor executing software; or a combination thereof. For example, the processing circuitry more specifically may include, but is not limited to, a central processing unit (CPU), an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA), a System-on-Chip (SoC), a programmable logic unit, a microprocessor, application-specific integrated circuit (ASIC), etc. According to some example embodiments, the control devicemay be partially or entirely included in the EH system, but some example embodiments are not limited thereto and at least one or more elements of the control devicemay be external to the EH system.

The processormay store and/or retrieve data to and/or from the memory(e.g., programming instructions for execution by the processor, operational data generated by the processor, etc.). The processormay communicate, and/or control, the communication deviceand/or the UI.

The memorymay be a tangible, non-transitory computer-readable medium, such as a Random Access Memory (RAM), a flash memory, a Read Only Memory (ROM), an Electrically Programmable ROM (EPROM), an Electrically Erasable Programmable ROM (EEPROM), registers, a hard disk, a removable disk, a Compact Disk (CD) ROM, any combination thereof, or any other form of storage medium known in the art. The memorymay store data and/or instructions for retrieval by, for example, the processor.

The communication devicemay include a transmitter, a receiver and/or a transceiver. The communication devicemay output one or more control signals, provided by the processor, to the first EH solenoidand/or the second EH solenoid. In scenarios in which the EH systemincludes a plurality of valves, the communication devicemay output the one or more control signals to one or more the second EH solenoids. The communication devicemay receive a pressure value from the pressure sensorand provide the pressure value to the processor. The communication devicemay communicate with the first EH solenoid, the second EH solenoid(s)and/or the pressure sensorvia any wired and/or wireless communication method that would be known to a person having ordinary skill in the art.

The temperature sensormay detect a temperature of the hydraulic oil of the EH systemand provide the temperature (may also be referred to herein as a temperature value) to the processor. The temperature sensormay be implemented using any sensor capable of detecting the temperature of hydraulic oil that would be known to a person having ordinary skill in the art.

The UImay include one or more devices for communicating information to, and/or receiving information from, an operator of the work vehicle. For example, the UEmay receive a command from the operator to initiate a warming mode and provide an indication of the command to the processor. Also, the UImay receive information from the processor(e.g., a hydraulic oil temperature value, a hydraulic oil pressure value, etc.) and display an indication of the information on a screen of the UI. Additionally or alternatively, the UImay communicate the information received from the processoraudibly (e.g., via a speaker of the UI), haptically (e.g., via a piezoelectric actuator of the UI), etc. According to some example embodiments, the control devicemay not include the UI. For example, the warming operations discussed herein may be performed as a background process without interaction from the operator.

The movement detectormay provide the processorwith information regarding whether the boom(e.g., any among the first actuatoror the hoist portion, the second actuatoror the stick portion, and/or the third actuatoror the bucket) is moving. According to some example embodiments, the movement detectormay receive commands (provided by the operator by, for example, moving a joystick of the work vehicle), for moving the boom, sent to the EH system. In such examples, the movement detectormay provide the processorwith a movement signal when the boomis being moved (or a non-movement when the boomis not being moved). According to some example embodiments, the movement detectormay detect when at least one valveis positioned to flow hydraulic oil to at least one actuator. In such examples, the movement detectormay provide the processorwith the movement signal while the hydraulic oil is flowing to the at least one actuator(or the non-movement in circumstances in which hydraulic oil is not flowing to any actuator). According to some example embodiments, operations performed by the movement detectormay be implemented using processing circuitry. According to some example embodiments the movement detectormay be implemented by the processor.

illustrates a method of warming hydraulic oil, according to some example embodiments. According to some example embodiments, the method may be performed by the processor.

Referring to, in operation, the method may include determining whether to perform a hydraulic oil warming operation. For example, the processormay determine whether a temperature of the hydraulic oil of the EH system(e.g., obtained by the temperature sensor) is greater than a target temperature. In response to determining that the temperature of the hydraulic oil of the EH systemis less than or equal to the target temperature (“Yes” in operation), the method may advance to operation. Otherwise, in response to determining that the temperature of the hydraulic oil of the EH systemis greater than the target temperature (“No” in operation), the method may repeat operationafter a certain period of time, but some example embodiments are not limited thereto.

According to some example embodiments, operationmay be initiated in response to receiving a command from an operator of the work vehicle via the UI. In such circumstances, in response to determining that the temperature of the hydraulic oil of the EH systemis greater than the target temperature (“No” in operation), the method may end and/or output a notification (e.g., indicating that the hydraulic oil warming operation has not been performed because temperature of the hydraulic oil is above the target temperature) to the UIrather than repeat operation.

According to some example embodiments, operationmay be initiated in response to determining (by the processor) that the work vehiclehas been idle for a threshold period of time (e.g., 60 seconds) or more. The work vehiclemay be interpreted as being idle when the boom(e.g., any or all among the first actuatoror the hoist portion, the second actuatoror the stick portion, and/or the third actuatoror the bucket) is not being moved. In such examples, the method ofmay be performed as illustrated until the processordetects that the work vehicleis no longer idle (e.g., based on a signal received from the movement detector) at which point the method may promptly end without performing any additional operation(s) of the method. After the method has been ended under these circumstances, operationmay be reinitiated in response to determining that the work vehiclehas again been idle for the threshold period of time or more.

According to some example embodiments, operationmay include determining the target temperature. For example, the target temperature may differ among different implementations of the EH systemand/or different types of hydraulic oil used in the EH system. The processormay obtain (e.g., via information stored in the memory, etc.), or be provided (e.g., via a transmission received through the communication devicefrom an external source, via an input through the UIprovided by the operator, etc.), such information about the current implementation of the EH systemand/or the current type of hydraulic oil in use in the EH system, and may determine (e.g., calculate) the target temperature using any corresponding algorithm that would be known to a person having ordinary skill in the art.

In operation, the method may include controlling the second EH solenoidto position the valvein one of the neutral position or the intermediate position. For example, the processormay generate a control signal configured to trigger the second EH solenoidto set the position of the valveto the neutral position or the intermediate position, and transmit the control signal to the second EH solenoidvia the communication device. In scenarios in which the EH systemincludes a plurality of valves, the processormay generate, and transmit, a respective control signal for (and to) a single one, two or more, or all among the plurality of valves.

According to some example embodiments, the processormay determine whether to position the valvein the neutral position or the intermediate position based on a difference between a current temperature of the hydraulic oil and the target temperature. For example, in response to determining that the current temperature of the hydraulic oil is within a threshold temperature range of the target temperature, the processormay position the valve in the neutral position. Alternatively, in response to determining that the current temperature of the hydraulic oil is not within the threshold temperature range of the target temperature, the processormay position the valve in the intermediate position in order to warm the hydraulic oil at a faster rate. In such cases, the processormay also reposition the valvefrom the intermediate position to the neutral position in response to determining that the current temperature of the hydraulic oil has warmed sufficiently to bring the current temperature within the threshold temperature range.

According to some example embodiments, in scenarios in which the EH systemincludes a plurality of valves, the processormay determine many valvesamong the plurality of valvesto position in the neutral position or the intermediate position based on a difference between a current temperature of the hydraulic oil and the target temperature. For example, the processormay position a greater quantity of valvesin the neutral or intermediate position in response to determining that the current temperature of the hydraulic oil is not within a threshold temperature range of the target temperature. In another example, the processormay determine a difference between the current temperature and the target temperature and position a quantity of valvesto the neutral or intermediate position proportional to the difference between the current temperature and the target temperature (e.g., using a fixed association(s) recorded in the memory, using a function stored in the memory, etc.). In so doing, the processormay warm the hydraulic oil at a faster rate in circumstances in which the current temperature of the hydraulic oil is substantially colder than the target temperature. Also, according to some example embodiments, the processor may control both the quantity of valvespositioned, and whether the each of the positioned valvesis set to the neutral position or the intermediate position, according to the difference between the current temperature and the target temperature. In such cases, the processormay also reposition one or more of the valvesfrom the intermediate position to the neutral position in response to determining that the current temperature of the hydraulic oil has warmed, reducing the difference between the current temperature and the target temperature.

According to some example embodiments, in implementations of the EH systemin which setting the valveto the intermediate position without the hydraulic oil being able to pass through the valveinto the third or fourth hydraulic lineoris impossible or difficult, an additional operation may be performed between operationsand. Specifically, this additional operation may include outputting a notification to the operator (e.g., via the UI) instructing the operator to place the boom(e.g., any among the hoist portion, the stick portionand/or the bucket) against a stop so as to render movement of the boomimpossible or difficult. In such examples, the method may advance to operationonly in response to receiving an indication (e.g., via the UI) from the operator indicating that the placement of the boomhas been successfully completed.

In operation, the method may include controlling the first EH solenoidto set a selected flow rate of the pump. For example, the processormay select a desired flow rate of the pump, generate a control signal configured to trigger the first EH solenoidto set the selected flow rate, and transmit the control signal to the first EH solenoidvia the communication device. According to some example embodiments, the processormay selected the desired flow rate according to a difference between a current temperature of the hydraulic oil and the target temperature of the hydraulic oil. For example, the processormay select a flow rate that is proportional to the difference between the current temperature and the target temperature (e.g., using a fixed association(s) recorded in the memory, using a function stored in the memory, etc.). In so doing, the processormay warm the hydraulic oil at a faster rate in circumstances in which the current temperature of the hydraulic oil is substantially colder than the target temperature. According to some example embodiments, the processormay control the flow rate of the pumpwith reference to a current pressure (e.g., provided by the pressure sensor) in order to maintain a desired pressure in the EH system.

According to some example embodiments, the processormay control one or more among the flow rate of the pump, the position of the valve(s)(e.g., the neutral position or the intermediate position) and/or the quantity of the valvesso positioned to enable hydraulic oil warming. According to some example embodiments, as discussed above, the processormay select a flow rate of the pump, the position of the valve(s)and/or the quantity of the valvesbased on the difference between the current temperature and the target temperature (e.g., using one or more fixed associations recorded in the memory, using one or more functions stored in the memory, etc.) to increase a rate of hydraulic oil warming in circumstances in which the current temperature of the hydraulic oil is substantially colder than the target temperature. In an example, the processormay set the valve, or all of the plurality of valves, to the neutral position in operation, and control the flow rate of the pumpin operationto achieve a desired rate of hydraulic oil warming based on the neutral positioning of the valve(s). In an example, the processorset the valve, or a selected quantity among the plurality of valves, to the intermediate position to achieve a desired rate of hydraulic oil warming in operation(based on a standard or default flow rate), and select the standard or default flow rate of the pumpin operation.

According to some example embodiments, the processormay only select the flow rate of the pumpthat is less than or equal to a maximum flow rate (e.g., an upper limit flow rate). For example, the processormay obtain (e.g., via information stored in the memory, etc.), or be provided (e.g., via a transmission received through the communication devicefrom an external source, via an input through the UIprovided by the operator, etc.), the maximum flow rate (the upper limit flow rate), or information sufficient to determine the maximum flow rate (the upper limit flow rate). The maximum flow rate (the upper limit flow rate) may reflect a maximum (or upper limit) noise level. Accordingly, the information sufficient to determine the maximum flow rate (the upper limit flow rate) may include an indication of a noise level (e.g., a decibel value). The processormay determine (e.g., calculate) the maximum flow rate (the upper limit flow rate) (e.g., using the information sufficient to determine the maximum flow rate (the upper limit flow rate)) using any corresponding algorithm or function that would be known to a person having ordinary skill in the art. Also, the amount of noise produced by the EH systemmay be based on both the flow rate of the pumpand the temperature of the hydraulic oil. Accordingly, the processormay determine (e.g., calculate) the maximum flow rate (the upper limit flow rate), or adjust the obtained the maximum flow rate (the upper limit flow rate) based on the current temperature of the hydraulic oil.

According to some example embodiments, operationmay be performed until the current temperature of the hydraulic oil becomes greater than the target temperature, at which point the method ends.

The various operations of methods described above may be performed by any suitable device capable of performing the operations, such as the processing circuitry discussed above. For example, as discussed above, the operations of methods described above may be performed by various hardware and/or software implemented in some form of hardware (e.g., processor, ASIC, etc.).

The software may comprise an ordered listing of executable instructions for implementing logical functions, and may be embodied in any “processor-readable medium” for use by or in connection with an instruction execution system, apparatus, or device, such as a single or multiple-core processor or processor-containing system.

The blocks or operations of a method or algorithm and functions described in connection with some example embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a tangible, non-transitory computer-readable medium (e.g., the memory).

According to some example embodiments, the memorymay each be a tangible, non-transitory computer-readable medium, such as a Random Access Memory (RAM), a flash memory, a Read Only Memory (ROM), an Electrically Programmable ROM (EPROM), an Electrically Erasable Programmable ROM (EEPROM), registers, a hard disk, a removable disk, a Compact Disk (CD) ROM, any combination thereof, or any other form of storage medium known in the art.

Some example embodiments may be described with reference to acts and symbolic representations of operations (e.g., in the form of flow charts, flow diagrams, data flow diagrams, structure diagrams, block diagrams, etc.) that may be implemented in conjunction with units and/or devices discussed in more detail below. Although discussed in a particular manner, a function or operation specified in a specific block may be performed differently from the flow specified in a flowchart, flow diagram, etc. For example, functions or operations illustrated as being performed serially in two consecutive blocks may actually be performed concurrently, simultaneously, contemporaneously, or in some cases be performed in reverse order.

It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it may be directly connected or coupled to the other element or intervening elements may be present. As used herein the term “and/or” includes any and all combinations of one or more of the associated listed items.

Although terms of “first” or “second” may be used to explain various components (or parameters, values, etc.), the components (or parameters, values, etc.) are not limited to the terms. These terms should be used only to distinguish one component from another component. For example, a “first” component may be referred to as a “second” component, or similarly, and the “second” component may be referred to as the “first” component. Expressions such as “at least one of” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. For example, the expression, “at least one of a, b, and c,” should be understood as including only a, only b, only c, both a and b, both a and c, both b and c, all of a, b, and c, or any variations of the aforementioned examples.