Patent Publication Number: US-2023151584-A1

Title: System and method for heating the hydraulic fluid of an electric work vehicle

Description:
FIELD OF THE INVENTION 
     The present disclosure generally relates to electric work vehicles and, more particularly, to systems and methods for heating the hydraulic fluid of an electric work vehicle, such as an electric backhoe loader, during low temperature operation. 
     BACKGROUND OF THE INVENTION 
     Work vehicles, such as backhoe loaders, wheel loaders, skid steer loaders, compact track loaders, and the like, are a mainstay of construction work and industry. As such, work vehicles typically include one or more implements for carrying materials, such as gravel, sand, or dirt, around a worksite. For example, backhoe loaders include a chassis, a loader assembly coupled to the front of the chassis, and a backhoe assembly coupled to the rear of the chassis. Moreover, work vehicles include a hydraulic system having one or more hydraulic cylinders for raising and lowering each implement relative to the chassis. 
     When operating a work vehicle in low temperature conditions, it is important to ensure the temperature of the hydraulic fluid supplied to the hydraulic cylinders is above a minimum temperature. When the temperature of the hydraulic fluid falls below the minimum temperature, the hydraulic fluid may be too viscous to be properly pumped through the hydraulic system of the work vehicle. In this respect, heat from the internal combustion engine of the work vehicle is typically used to heat the hydraulic fluid when ambient temperatures are low. However, electric work vehicles do not include an internal combustion engine or other device that generates significant amounts of excess heat that can be used to heat the hydraulic fluid. 
     Accordingly, a system and method for heating the hydraulic fluid of an electric work vehicle would be welcomed in the technology. In particular, a system and method for heating the hydraulic fluid of an electric work vehicle during low temperature operation would be welcomed in the technology. 
     SUMMARY OF THE INVENTION 
     Aspects and advantages of the technology will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the technology. 
     In one aspect, the present subject matter is directed to an electric work vehicle. The electric work vehicle includes a chassis and an electric motor supported on the chassis, with the electric motor configured to propel the electric construction vehicle in a direction of travel. Additionally, the electric work vehicle includes an implement adjustably coupled to the chassis and a hydraulic actuator configured to adjust a position of the implement relative to the chassis. Furthermore, the electric work vehicle includes a pump configured to supply hydraulic fluid to the hydraulic actuator, with the pump being operable within an operating speed range extending between a minimum operating speed value and a maximum operating speed value. Moreover, the electric work vehicle includes a sensor configured to capture data indicative of a temperature of the hydraulic fluid and a controller communicatively coupled to the sensor. As such, the controller is configured to monitor the temperature of the hydraulic fluid relative to a predetermined minimum fluid temperature as the pump is operating within the operating speed range. In addition, the controller is configured to adjust the operating speed range of the pump by increasing at least one of the minimum operating speed value or the maximum operating speed value when the monitored temperature of the hydraulic fluid falls below the predetermined minimum fluid temperature. 
     In another aspect, the present subject matter is directed to a system for heating hydraulic fluid of an electric work vehicle. The system includes a pump configured to supply hydraulic fluid to a component of the electric work vehicle. Additionally, the system includes a sensor configured to capture data indicative of a temperature of the hydraulic fluid and a controller communicatively coupled to the sensor. As such, the controller is configured to monitor the temperature of the hydraulic fluid relative to a predetermined minimum fluid temperature based on data received from the sensor. Furthermore, the controller is configured to adjust an operating speed range of the pump when the monitored temperature of the hydraulic fluid falls below the predetermined minimum fluid temperature. 
     In a further aspect, the present subject matter is directed to a method for heating hydraulic fluid of an electric work vehicle. The electric work vehicle, in turn, includes a pump configured to supply the hydraulic fluid to a component of the electric work vehicle. The method includes receiving, with one or more computing devices, sensor data indicative of a temperature of the hydraulic fluid. Furthermore, the method includes monitoring, with the one or more computing devices, the temperature of the hydraulic fluid relative to a predetermined minimum fluid temperature based on the received sensor data. Moreover, when the monitored temperature of the hydraulic fluid falls below the predetermined minimum fluid temperature, the method includes adjusting, with the one or more computing devices, an operating speed range of the pump. 
     These and other features, aspects and advantages of the present technology will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the technology and, together with the description, serve to explain the principles of the technology. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present technology, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
         FIG.  1    illustrates a side view of one embodiment of electric work vehicle in accordance with aspects of the present subject matter; 
         FIG.  2    illustrates a schematic view of one embodiment of a system for heating the hydraulic fluid of an electric work vehicle in accordance with aspects of the present subject matter; and 
         FIG.  3    illustrates a flow diagram of one embodiment of a method for heating the hydraulic fluid of an electric work vehicle in accordance with aspects of the present subject matter. 
     
    
    
     Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present technology. 
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     In general, the present subject matter is directed to systems and methods for heating hydraulic fluid of an electric work vehicle. As will be described below, the present subject matter may be used with an electric backhoe loader or any other electric work vehicle that uses hydraulic fluid to operate one or more of its components. In this respect, the electric work vehicle may include one or more hydraulic actuators configured to adjust the position(s) of one or more implements (e.g., a loader assembly and/or a backhoe assembly) relative to a chassis of the vehicle. Moreover, the electric work vehicle may include a pump configured to supply hydraulic fluid to the hydraulic actuator(s), with the pump being operable within an operating speed range extending between a minimum operating speed value and a maximum operating speed value. 
     In accordance with aspects of the present subject matter, a controller of the disclosed system may be configured to adjust the operating speed range of the pump to heat the hydraulic fluid of the work vehicle. Specifically, in several embodiments, the controller may be configured to monitor the temperature of the hydraulic fluid supplied by the pump relative to a predetermined minimum fluid temperature. Thereafter, when the monitored temperature falls below the predetermined minimum fluid temperature, the controller may be configured to adjust the operating speed range of the pump. For example, the controller may be configured to adjust the operating speed range of the pump by increasing the minimum operating speed value and/or the maximum operating speed value of the operating speed range of the pump. Adjusting the operating speed range of the pump when the temperature of the hydraulic fluid is below the predetermined minimum fluid temperature may, in turn, ensure the pump is operating at an operating speed sufficient to quickly heat the hydraulic fluid, while minimizing energy consumption of the electric work vehicle. 
     Referring now to the drawings,  FIG.  1    illustrates a side view of one embodiment of an electric work vehicle in accordance with aspects of the present subject matter. As shown, the electric work vehicle is configured as an electric backhoe loader  10  (also often referred to as a “tractor-loader-backhoe” (TLB) or a “loader backhoe”). However, in other embodiments, aspects of the present subject matter may also be utilized within other electric work vehicles, such as various other construction vehicles. For instance, in one embodiment, aspects of the present subject matter may be advantageously utilized with other electric construction vehicles including at least one hydraulically-driven work implement assembly, such as a wheel loader, a skid-steer loader, and/or a bulldozer. 
     As shown in  FIG.  1   , the backhoe loader  10  includes a frame or chassis  12  extending in a longitudinal direction (indicated by arrow  14  in  FIG.  1   ) of the vehicle  10  between a forward end  16  of the chassis  12  and an aft end  18  of the chassis  12 . In general, the chassis  12  may be configured to support or couple to a plurality of components. For example, a pair of steerable front traction devices (e.g., front wheels  20  (one of which is shown)) and a pair of driven rear traction devices (e.g., rear wheels  22  (one of which is shown)) may be coupled to the chassis  12 . The wheels  20 ,  22  may be configured to support the backhoe loader  10  relative to a ground surface  24  and move the loader  10  along the ground surface  24  in a direction of travel, such as a forward direction of travel (e.g., as indicated by arrow  26  in  FIG.  1   ). However, in alternative embodiments, the front wheels  20  may be driven in addition to or in lieu of the rear wheels  22 . Additionally, an operator&#39;s cab  28  may be supported by a portion of the chassis  12  positioned between the forward and aft ends  16 ,  18  of the chassis  12 , and may house one or more operator control devices  30  (e.g., a joystick(s), a lever(s), and/or the like) for permitting an operator to control the operation of the backhoe loader  10 . 
     The backhoe loader  10  also includes a pair of hydraulically-driven work implement assemblies positioned at the opposed ends  16 ,  18  of the chassis  12 . Specifically, in the illustrated embodiment, the backhoe loader  10  includes a loader assembly  40  supported by or relative the chassis  12  at or adjacent to its forward end  16 . As shown in  FIG.  1   , the loader assembly  40  includes a loader arm  42  pivotably coupled or supported relative to the chassis  12  at a loader arm pivot point  44 , and a loader lift cylinder  46  secured between the loader arm  42  and the chassis  12 . In such an embodiment, extension/retraction of the loader lift cylinder  46  may result in the loader arm  42  pivoting upwards/downwards about its respective pivot point  44 , thereby allowing the positioning of the loader arm  42  relative to both the chassis  12  and the ground surface  24  to be adjusted, as desired. Moreover, as shown in  FIG.  1   , the loader assembly  40  further includes a first work implement  48 , such as a loader bucket, coupled to the loader arm  42  at an implement pivot point  50 , and a first implement tilt cylinder  52  secured between the work implement  48  (e.g., via a linkage(s)  54 ) and a portion of the loader arm  44 . As such, extension/retraction of the first implement tilt cylinder  52  may result in the first work implement  48  pivoting upwards/downwards relative to the loader arm  42  about its respective pivot point  50 , thereby permitting the tilt angle or orientation of the implement  48  to be adjusted, as desired. Thus, by controlling the operation of the lift and tilt cylinders  46 ,  52  of the loader assembly  40 , the vertical positioning and orientation of the first work implement  48  may be adjusted to allow for the execution of one or more operations, such as one or more material-moving operations. 
     Additionally, the backhoe loader  10  includes a backhoe assembly  60  supported by or relative to the chassis  12  at or adjacent to its aft end  18 . As shown in  FIG.  1   , the backhoe assembly  60  includes a boom  62  pivotably coupled or supported relative to the chassis  12  at a boom pivot point  64 , and a boom lift cylinder  66  secured between the boom  62  and the chassis  12 . In such an embodiment, extension/retraction of the boom cylinder  66  may result in the boom  62  pivoting upwards/downwards about its respective pivot point  64 , thereby allowing the positioning of the boom  62  relative to both the chassis  12  and the ground surface  24  to be adjusted, as desired. The backhoe assembly  60  also includes a dipper arm  68  coupled to the boom  62  at a dipper pivot point  70 , and a dipper cylinder  72  secured between the dipper arm  68  and the boom  62 . In such an embodiment, extension/retraction of the dipper cylinder  72  may result in the dipper arm  68  pivoting upwards/downwards about its respective pivot point  70  relative to the boom  62 . Moreover, as shown in  FIG.  1   , the backhoe assembly  60  further includes a second work implement  74 , such as a dipper bucket, coupled to the dipper arm  68  at an implement pivot point  76 , and a second implement tilt cylinder  78  secured between the work implement  74  and a portion of the dipper arm  68 . As such, extension/retraction of the second implement tilt cylinder  78  may result in the second work implement  74  pivoting upwards/downwards relative to the dipper arm  68  about its respective pivot point  76 , thereby permitting the tilt angle or orientation of the implement  74  to be adjusted, as desired. Thus, by controlling the operation of the various cylinders  66 ,  72 ,  78  of the backhoe assembly  60 , the vertical positioning and orientation of the second work implement  74  may be adjusted to allow for the execution of one or more operations, such as one or more material excavation operations. 
     As shown in  FIG.  1   , the backhoe loader  10  may also include a pair of stabilizer legs  78  (one of which is shown) positioned at or adjacent to the aft end  18  of the chassis  12 . The stabilizer legs  78  may be configured to support the weight of the backhoe loader  10  and/or otherwise stabilize the loader  10  during the performance of a backhoe-related operation. For instance, the stabilizer legs  78  may be pivotably coupled to the chassis  12  to allow the legs  78  to be moved or pivoted (e.g., via the operation of an associated stabilizer leg cylinder  78 ) between a lowered position, at which the legs  78  contact the ground surface  24 , and a raised position, at which the legs  78  are lifted off the ground surface  24  to allow movement of the backhoe loader  10  (e.g., in the forward direction of travel  26 ). In addition to lowering the stabilizer legs  78 , the loader assembly  40  may also be lowered during the performance of a backhoe-related operation such that the first work implement  48  contacts the ground, thereby providing a point-of-contact to stabilize the front end  16  of the chassis  12 . 
     Furthermore, the backhoe loader  10  may include an electric drivetrain configured to propel the loader  10  in the direction of the travel  26 . For example, in the illustrated embodiment, the electric drivetrain includes a power storage device, such as a battery module  80  having three batteries  82 , supported on and positioned adjacent to the forward end  16  of the chassis  12 . Moreover, in the illustrated embodiment, the electric drivetrain includes a pair of electric traction motors  84  (one of which is shown) supported on the chassis  12 , with each motor  84  coupled to one of the driven wheels  22  via a suitable shaft (not shown). More specifically, the batteries  82  may be configured to provide electric power for use in powering the electric traction motors  84  and other power-consuming components of the vehicle  10  (e.g., an electric hydraulics-driving motor  102  ( FIG.  2   ) of the loader  10 ). Each electric traction motor  84  may, in turn, rotationally drive the corresponding rear wheel  22 , thereby propelling the backhoe loader  10  in the forward direction of travel  26 . However, in alternative embodiments, the electric drivetrain of the backhoe loader  10  may have any other suitable configuration. For example, in one embodiment, the backhoe loader  10  may include as a single electric traction motor coupled to a transmission (not shown) that transmits the torque generated by the electric traction motor to each of the rear wheels  22 . In another embodiment, the backhoe loader  10  may include an electric traction motor coupled to each of the wheels  20 ,  22 . Furthermore, the battery module  80  may include any other suitable number of batteries  82 . 
     In addition, the backhoe loader  10  may include various components for controlling the operation of the electric drivetrain. For instance, although not shown, one or more power inverters may be coupled to the battery module  80  via a direct current (DC) voltage bus or any other suitable electrical coupling for converting the direct current supplied by the batteries  82  of the battery module  80  to an alternating current (AC) for powering the electric traction motors  84  and the electric hydraulics-driving motor  102 . An associated motor/inverter controller(s) may control the operation of the power inverter(s) in a manner that drives each electric motor  84 ,  102  as desired, such as by ensuring that each motor  84 ,  102  is driven to achieve a desired speed and/or torque output. 
     The configuration of the electric work vehicle  10  described above and shown in  FIG.  1    is provided only to place the present subject matter in an exemplary field of use. Thus, the present subject matter may be readily adaptable to any manner of electric vehicle configuration. For instance, in addition to a backhoe loader, aspects of the present subject matter may also be applied within electric construction vehicles only including a single work implement assembly positioned at one end of the vehicle&#39;s chassis, such as a wheel loader, skid-steer loader, bulldozer, and/or the like. 
     Referring now to  FIG.  2   , a schematic view of one embodiment of a system  100  for heating the hydraulic fluid of an electric work vehicle is illustrated in accordance with aspects of the present subject matter. In general, the system  100  will be described herein with reference to the electric work vehicle  10  described above with reference to  FIG.  1   . However, the disclosed system  100  may generally be utilized with electric work vehicle having any other suitable electric vehicle configuration. For purposes of illustration, hydraulic connections between components of the system  100  are shown in solid lines, while electrical connections between components of the system  100  are shown in dashed lines. 
     As shown in  FIG.  2   , the system  100  may include various components of the hydraulic system of the backhoe loader  10 . In several embodiments, the system  100  may include a pump  104  configured to supply hydraulic fluid to one or more hydraulic actuators of the loader  10 , such as the hydraulic cylinders  46 ,  52 ,  66 ,  72 ,  78 . More specifically, the pump  104  may be in fluid communication with a fluid tank or reservoir  106  (via a pump line  108 ) and one or more control valves  110  (e.g., via a supply line  112 ). The control valve(s)  106  may, in turn, be in fluid communication with the hydraulic cylinders  46 ,  52 ,  66 ,  72 ,  78  (e.g., via the cylinder lines  114 —one is shown in  FIG.  2   ) and the reservoir  108  (e.g., via a return line  116 ). In this respect, the pump  104  may be configured to receive hydraulic fluid from the reservoir  106  (e.g., via the pump line  108 ) and discharge a pressurized flow of the hydraulic fluid into the supply line  112 . The control valve(s)  106  may regulate the flow of the pressurized hydraulic fluid from the supply line  112  to each of the hydraulic cylinders  46 ,  52 ,  66 ,  72 ,  78 . By regulating the flow of hydraulic fluid generated by the pump  104  (e.g., by controlling the operation of the pump  104  and/or the control valve(s)  110 ), the movement of the loader assembly  40  and the backhoe assembly  60  may be to be controlled. In addition, the control valve(s)  110  may regulate the return of the hydraulic fluid from the hydraulic cylinders  46 ,  52 ,  66 ,  72 ,  78  to the reservoir  106 . 
     The pump  104  may be operable within an operating speed range (e.g., a rotational speed range of an impeller of the pump  104 ) to pressurize the received hydraulic fluid for supply to the hydraulic cylinders  46 ,  52 ,  66 ,  72 ,  78 . In general, the operating speed range may extend between a minimum operating speed value (e.g., a minimum rotational speed value of the impeller) and a maximum operating speed value (e.g., a minimum rotational speed value of the impeller). By operating pump  104  within the operating speed range, the pump  104  may discharge hydraulic fluid within a range of pressures into the supply line  112 . In this respect, the operating speed of the pump  104  may be adjusted within the operating speed range based on the load placed on the hydraulic system of the backhoe loader  10 . For example, the operating speed of the pump  104  may be increased toward the maximum operating speed value to increase the pressure of the hydraulic fluid discharged by the pump  104 , thereby allowing the hydraulic system to handle a greater load (e.g., due to movement of the hydraulic cylinders  46 ,  52 ,  66 ,  72 ,  78 ). Conversely, the operating speed of the pump  104  may be decreased toward the minimum operating speed value to decrease the pressure of the hydraulic fluid discharged by the pump  104 , thereby reducing the power consumption of the backhoe loader  10  when the hydraulic system operating at lower loads. As will be described below, the operating speed range of the pump  104  may be adjusted when the temperature of the hydraulic fluid in the hydraulic system falls below a predetermined minimum fluid temperature to quickly heat the hydraulic fluid. 
     In several embodiments, the pump  104  may be driven by an electric hydraulics-driving motor  102 . More specifically, in such embodiments, the electric hydraulics-driving motor  102  may be powered by the battery module  80  ( FIG.  1   ) and mechanically coupled to the pump  104  via an output shaft  118 . In this respect, a motor/inverter controller and associated power inverter may control the operation of the electric hydraulics-driving motor  102  such that the electric hydraulics-driving motor  102  rotationally drives the impeller of the pump  104  at an operating speed within the operating speed range based on the load applied to the hydraulic system of the backhoe loader  10 . 
     Referring still to  FIG.  3   , the system  100  may include one or more heat exchangers  120  for cooling the hydraulic fluid flowing through the hydraulic system of the backhoe loader  10 . Additionally, as shown, one or more electric cooling fans  122  (e.g., an array of cooling fans, such as a  2 x 2  array or a  4 x 4  array) may be positioned adjacent to the heat exchanger(s)  120  for generating an airflow through the heat exchanger(s)  120 . The airflow generated by the electric cooling fans  122  may also, in one embodiment, be directed around other components (e.g., the battery module  80  and/or other heat exchangers) to provide a cooling airflow thereto. In one embodiment, the electric cooling fans  122  may correspond to DC-powered cooling fans to allow the battery module  80  to serve as a direct power source for the fans  122 . 
     Furthermore, the system  100  may include a temperature sensor  124  in operative association with the hydraulic system of the backhoe loader  10 . In general, the temperature sensor  124  may be configured to capture data indicative of the temperature of the hydraulic fluid within the hydraulic system. For example, in several embodiments, the temperature sensor  124  may be configured as a thermocouple or a thermistor. Moreover, in the illustrated embodiment, the temperature sensor  124  is in operative association with supply line  112  such that the temperature sensor  124  is in contact with the hydraulic fluid flowing through the supply line  112 . However, in alternative embodiments, the temperature sensor  124  be configured as any other suitable device for capturing data indicative of the temperature of the hydraulic fluid and/or be in operative association with any other suitable component of the hydraulic system. 
     In accordance with aspects of the present subject matter, the system  100  may include a controller  126  positioned on and/or within or otherwise associated with the backhoe loader  10 . In general, the controller  126  may comprise any suitable processor-based device known in the art, such as a computing device or any suitable combination of computing devices. Thus, in several embodiments, the controller  126  may include one or more processor(s)  128  and associated memory device(s)  130  configured to perform a variety of computer-implemented functions. As used herein, the term “processor” refers not only to integrated circuits referred to in the art as being included in a computer, but also refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, and other programmable circuits. Additionally, the memory device(s)  130  of the controller  126  may generally comprise memory element(s) including, but not limited to, a computer readable medium (e.g., random access memory (RAM)), a computer readable non-volatile medium (e.g., a flash memory), a floppy disc, a compact disc-read only memory (CD-ROM), a magneto-optical disc (MOD), a digital versatile disc (DVD), and/or other suitable memory elements. Such memory device(s)  130  may generally be configured to store suitable computer-readable instructions that, when implemented by the processor(s)  128 , configure the controller  126  to perform various computer-implemented functions. 
     In addition, the controller  126  may also include various other suitable components, such as a communications circuit or module, a network interface, one or more input/output channels, a data/control bus and/or the like, to allow controller  126  to be communicatively coupled to any of the various other system components described herein (e.g., the electric hydraulics-driving motor  102  (or an associated inverter), the valve(s)  110 , the fan(s)  122 , and/or the temperature sensor  124 ). For instance, as shown in  FIG.  2   , a communicative link or interface  132  (e.g., a data bus) may be provided between the controller  126  and the components  102 ,  110 ,  122 ,  124  to allow the controller  126  to communicate with such components  102 ,  110 ,  122 ,  124  via any suitable communications protocol (e.g., CANBUS). 
     The controller  126  may correspond to an existing controller(s) of the backhoe loader  10 , itself, or the controller  126  may correspond to a separate processing device. For instance, in one embodiment, the controller  126  may form all or part of a separate plug-in module that may be installed in association with the backhoe loader  10  to allow for the disclosed systems to be implemented without requiring additional software to be uploaded onto existing control devices of the backhoe loader  10 . 
     The functions of the controller  126  may be performed by a single processor-based device or may be distributed across any number of processor-based devices, in which instance such devices may be considered to form part of the controller  126 . For instance, the functions of the controller  126  may be distributed across multiple application-specific controllers, such as a vehicle controller, a hydraulic system controller, an electric traction motor controller/electric traction motor inverter controller, an electric hydraulics-driving motor controller/electric hydraulics-driving motor inverter controller, and/or the like. 
     In several embodiments, the controller  126  may be configured to monitor the temperature of the hydraulic fluid within the hydraulic system of the backhoe loader  10 . As described above, the backhoe loader  10  may include a temperature sensor  124  configured to capture data indicative of the temperature of the hydraulic fluid. In this respect, during operation of the backhoe loader  10 , the controller  126  may be configured to receive the captured data from the temperature sensor  124  (e.g., via the communicative link  132 ). Thereafter, the controller  126  may be configured to process/analyze the received sensor data to determine the temperature of the hydraulic fluid within the hydraulic system. For instance, the controller  126  may include a look-up table(s) and/or suitable mathematical formula stored within its memory device(s)  130  that correlates the received sensor data to the temperature of the hydraulic fluid. 
     In accordance with aspects of the present subject, the controller  126  may be configured to adjust the operating speed range of the pump  104  when the monitored temperature of the hydraulic fluid falls below a predetermined minimum fluid temperature. As described above, the pump  104  is operable within an operating speed range to pressurize the hydraulic fluid within the hydraulic system of the backhoe loader  10  for supply to the various hydraulic actuators of the loader  10 , such as the hydraulic cylinders  46 ,  52 ,  66 ,  72 ,  78 . However, when the temperature of the hydraulic fluid is too low (e.g., due to low ambient temperature and/or start-up of the backhoe loader  10 ), the hydraulic fluid may be too viscous to properly flow through the hydraulic system of the backhoe loader  10 . Continuous operation of the hydraulic system when the hydraulic fluid is too viscous may, in turn, accelerate the rate at which the pump  104  and/or other hydraulic system components incur wear. In this respect, the controller  126  may be configured to compare the monitored temperature of the hydraulic fluid to the predetermined minimum fluid temperature. Thereafter, when the monitored temperature of the hydraulic fluid falls below the predetermined minimum fluid temperature (thereby indicating that the hydraulic fluid is too cold and, thus, too viscous), the controller  126  may be configured to adjust the operating speed range of the pump  104 . As will be described below, such an adjustment of the operating speed range of the pump  104  may rapidly heat the hydraulic fluid, thereby decreasing its viscosity and allowing the hydraulic fluid to flow through the hydraulic system of the backhoe loader  10 . 
     In several embodiments, the controller  126  may be configured to increase the minimum or maximum operating speed values of the pump  104  when the monitored temperature of the hydraulic fluid falls below a predetermined minimum fluid temperature. For example, in one embodiment, the controller  126  may be configured to increase the minimum operating speed value of the pump  104  in such instances. Increasing the minimum operating speed value may, in turn, prevent the operating speed of the pump  104  from dropping below an operating speed that quickly heats the hydraulic fluid when the load on the hydraulic system is low. In another embodiment, the controller  126  may be configured to increase the maximum operating speed value of the pump  104 , such as to the maximum speed at which the pump  104  is capable of operating, when the monitored temperature of the hydraulic fluid falls below a predetermined minimum fluid temperature. Increasing the maximum operating speed value may, in turn, allow the pump  104  to operate at an operating speed above its normal operation speed range to more quickly heat the hydraulic fluid. 
     Additionally, in some embodiments, the controller  126  may be configured adjust the operating speed range of the pump  104  from a first or lower operating speed range to a second or higher operating speed range of the pump  104  when the monitored temperature of the hydraulic fluid falls below a predetermined minimum fluid temperature. In general, the minimum and maximum operating speed values of the higher operating speed range may be greater than the minimum and maximum operating speed values of the lower operating speed range, respectively. Adjusting from the lower operating speed range to the higher operating speed range may, in turn, allow the pump  104  to operate as if a higher load were placed on the hydraulic system, thereby more quickly heat the hydraulic fluid. For example, in one embodiment, when the monitored temperature of the hydraulic fluid falls below a predetermined minimum fluid temperature, the operating speed range may be adjusted from a first range (e.g., 800-1000 rpm) associated with a low hydraulic system load to a second range (e.g., 900-1100 rpm) associated with a high hydraulic system load. However, in alternative embodiments, the minimum operating speed value of the higher range may be greater than the maximum operating speed value of the lower operating range. 
     Furthermore, the controller  126  may be configured to control the operation of the pump  104  based on the adjusted operating speed range. Specifically, the controller  126  may be configured to compare the current operating speed of the pump  104  to the adjusted operating speed range. Thereafter, when the current operating speed of the pump  104  falls outside of the adjusted operating speed range (thereby indicating the operating speed of the pump  104  is too low to quickly heat the hydraulic fluid), the controller  126  may be configured to initiate an adjustment to the current operating speed of the pump  104 . For example, as described above, in several embodiments, the pump  104  may be driven by the electric hydraulics-driving motor  102 . In such embodiments, the controller  126  may transmit suitable controls signals to an inverter of the electric hydraulics-driving motor  102  instructing the inverter to increase the voltage of the electric power supplied to the motor  102 , thereby increasing the operating speed of the pump  104 . The increased operating speed of the pump  104  may, in turn, increase the rate at which the hydraulic fluid is heated due to the increased friction between the impeller of the pump  104  and the hydraulic fluid as well as the increased fluid pressure within the hydraulic system. However, in alternative embodiments, the controller  126  may be configured to control the operation of the pump  104  in any other suitable manner. 
     Adjusting the operating speed range of the pump  104  when the temperature of the hydraulic fluid is below the predetermined minimum fluid temperature may allow the pump to operate at an operating speed that quickly heats the hydraulic fluid, while minimizing energy consumption. Specifically, such an adjustment prevents the operating speed of the pump  104  from falling below an operating speed at which the hydraulic fluid is quickly heated (e.g., the adjusted minimum operating speed value) when the temperature of the hydraulic fluid is below the predetermined minimum fluid temperature. Moreover, adjusting the operating speed range prevents the operating speed of the pump from being unnecessarily increased when the operating speed of the pump is already sufficient to quickly heat the hydraulic fluid, thereby reducing the energy consumption of the electric work vehicle. As such, adjusting the operating speed range of the pump as opposed to simply increasing the operating speed of the pump  104  when the temperature of the hydraulic fluid is below the predetermined minimum fluid temperature improves the operation of the backhoe loader  10  during low temperature operating conditions. 
     Additionally, in one embodiment, the controller  126  may be configured to halt the operation of the fan(s)  122  when the monitored temperature of the hydraulic fluid is below the predetermined minimum fluid temperature. As described above, one or fans  122  may be configured to generate an airflow across one or more heat exchangers  120  through which the hydraulic fluid flows. In this respect, the cooling provided by the fan(s)  122  may reduce the rate at which the hydraulic fluid is heated. As such, when the monitored temperature of the hydraulic fluid is below the predetermined minimum fluid temperature, the controller  126  may actuate one or more switches (not shown) to halt the flow of electric power from the battery module  80  ( FIG.  1   ) to the fan(s)  122 , thereby shutting off the fan(s)  122 . Such halting of the fan(s)  122  may allow the operation of the pump  104  within adjusted operating speed to more quickly heat the hydraulic fluid. 
     Referring now to  FIG.  3   , a flow diagram of one embodiment of a method  200  for heating the hydraulic fluid of an electric work vehicle is illustrated in accordance with aspects of the present subject matter. In general, the method  200  will be described herein with reference to the electric work vehicle  10  and the system  100  described above with reference to  FIGS.  1  and  2   . However, the disclosed method  200  may generally be implemented with any electric work vehicle having any suitable electric vehicle configuration and/or within any system having any suitable system configuration. In addition, although  FIG.  3    depicts steps performed in a particular order for purposes of illustration and discussion, the methods discussed herein are not limited to any particular order or arrangement. One skilled in the art, using the disclosures provided herein, will appreciate that various steps of the methods disclosed herein can be omitted, rearranged, combined, and/or adapted in various ways without deviating from the scope of the present disclosure. 
     As shown in  FIG.  3   , at ( 202 ), the method  200  may include receiving, with one or more computing devices, sensor data indicative of a temperature of hydraulic fluid. For instance, as described above, the controller  126  may be configured to receive data from the temperature sensor  124  (e.g., via the communicative link  132 ) indicative of the temperature of the hydraulic fluid within the hydraulic system of the backhoe loader  10 . 
     Additionally, at ( 204 ), the method  200  may include monitoring, with the one or more computing devices, the temperature of the hydraulic fluid relative to a predetermined minimum fluid temperature based on the received sensor data. For instance, as described above, the controller  126  may be configured to monitor the temperature of the hydraulic fluid relative to a predetermined minimum fluid temperature based on the received sensor data. 
     Moreover, as shown in  FIG.  3   , at ( 206 ), when the monitored temperature of the hydraulic fluid falls below the predetermined minimum fluid temperature, the method  200  may include adjusting, with the one or more computing devices, an operating speed range of a pump. For instance, as described above, when the monitored temperature of the hydraulic fluid falls below the predetermined minimum fluid temperature, the controller  126  may be configured to adjust the operating speed range of the pump  104 . 
     It is to be understood that the steps of the method  200  are performed by the controller  126  upon loading and executing software code or instructions which are tangibly stored on a tangible computer readable medium, such as on a magnetic medium, e.g., a computer hard drive, an optical medium, e.g., an optical disc, solid-state memory, e.g., flash memory, or other storage media known in the art. Thus, any of the functionality performed by the controller  126  described herein, such as the method  200 , is implemented in software code or instructions which are tangibly stored on a tangible computer readable medium. The controller  126  loads the software code or instructions via a direct interface with the computer readable medium or via a wired and/or wireless network. Upon loading and executing such software code or instructions by the controller  126 , the controller  126  may perform any of the functionality of the controller  126  described herein, including any steps of the method  200  described herein. 
     The term “software code” or “code” used herein refers to any instructions or set of instructions that influence the operation of a computer or controller. They may exist in a computer-executable form, such as machine code, which is the set of instructions and data directly executed by a computer&#39;s central processing unit or by a controller, a human-understandable form, such as source code, which may be compiled in order to be executed by a computer&#39;s central processing unit or by a controller, or an intermediate form, such as object code, which is produced by a compiler. As used herein, the term “software code” or “code” also includes any human-understandable computer instructions or set of instructions, e.g., a script, that may be executed on the fly with the aid of an interpreter executed by a computer&#39;s central processing unit or by a controller. 
     This written description uses examples to disclose the technology, including the best mode, and also to enable any person skilled in the art to practice the technology, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the technology is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.