Multifunctional transmission control valve with integrated load braking function

Abstract

A self-propelled work vehicle comprises a chassis and several wheels or tracks that support the chassis on a ground surface. A battery supplies electrical power to an electric motor. A hydraulic pump feeds hydraulic fluid into a hydraulic system. A steering valve directs hydraulic fluid from the hydraulic system to a steering actuator. A steering priority valve prioritizes the flow of hydraulic fluid from the hydraulic system to the steering valve. A proportional relief valve transmits a load-sensing signal to the load-sensing port of the steering priority valve, which moves the steering priority slide to build up hydraulic system pressure. A controller is configured to detect whether the battery can be further charged and to control the operation of the proportional relief valve to apply a hydraulic braking function provided by the steering priority valve.

Description

AREA OF REVELATION

[0001] The present disclosure relates generally to battery-powered work vehicles, e.g., in the construction industry and / or in agriculture. In particular, the present disclosure relates to an improved system for providing a load-braking function in a battery-powered work vehicle using the hydraulic system. BACKGROUND

[0002] Battery-powered work vehicles discussed here may, for illustrative purposes, be referred to as electric backhoe loaders; however, such a designation does not constitute a limitation of the scope of protection, and unless specifically noted otherwise, alternative work vehicles may include, for example, excavators, compact wheeled or tracked loaders, graders, dump trucks, and the like. These machines may have tracked or wheeled locomotion devices that support the chassis on the ground surface and may further include one or more working attachments used to modify the working environment in accordance with a movement of the machine (e.g., to dig, lift, load, or level).

[0003] In the field of such work vehicles, there remains a need to reduce diesel emissions while maintaining the required performance. Some jurisdictions are planning to completely eliminate diesel emissions from passenger cars, which could further increase the demand for fully electric or hybrid diesel work vehicles. The potential benefits of fully electric work vehicles include not only reduced emissions of nitrogen oxides and particulate matter, but also reduced maintenance time, noise in the work environment, and, of course, fuel savings.

[0004] One operating mode to consider for a battery-powered electric vehicle is regenerative braking. When braking is desired, it is desirable to use the vehicle's kinetic energy to drive the electric motor in reverse, so that the motor acts as a generator to recuperate electrical energy. This provides the necessary braking effect and generates electrical energy, thus extending the electric vehicle's operating time.

[0005] Under certain conditions, however, the battery may not be able to absorb this additional electrical energy. The battery may already be fully charged, or it may be too hot or too cold to accept additional electrical energy. In such situations, it may be necessary to provide an additional load brake to distribute the vehicle's kinetic energy. SUMMARY OF THE REVELATION

[0006] The present disclosure provides an improved hydraulic system that provides a hydraulic load braking function, using components that are already present on the vehicle for other purposes.

[0007] In one embodiment, a self-propelled work vehicle comprises a vehicle frame and several wheels or tracks that support the vehicle frame on a ground surface. One or more work implements can be supported by the vehicle frame. A battery supplies an electric motor with electrical energy. The electric motor can be configured in a driving mode to use electrical power from the battery to drive one or more of the wheels or tracks, and can be configured in a regenerative mode to regenerate electrical power for storage in the battery when the electric motor is driven by the vehicle's kinetic energy. A hydraulic pump is driven directly or indirectly by the electric motor to supply hydraulic fluid to the vehicle's hydraulic system.A steering valve is configured to direct hydraulic fluid from the hydraulic system to a steering actuator for steering the vehicle. A steering priority valve is configured to prioritize the supply of hydraulic fluid from the hydraulic system to the steering valve. The steering priority valve includes a load sensing input port. A proportional relief valve is connected to the steering priority valve to supply a load sensing signal to the steering priority valve's load sensing input port. A controller is configured to detect whether the battery can continue charging and, in response to a determination that the battery should no longer be charged, to send an adjustment command signal to the proportional relief valve.According to the command, the proportional relief valve can increase the load sensing signal from the proportional relief valve to the load sensing input port of the steering priority valve, thus increasing a standby pressure in the hydraulic system between the pump and the steering priority valve, thereby increasing the load on the pump to provide a hydraulic load braking function.

[0008] The controller can also be configured to detect a battery charging rate, and the adaptation command signal can be based, at least in part, on the detected battery charging rate.

[0009] In another embodiment, a method for operating the vehicle according to the above description may include the following: in a drive mode, using electrical power from the battery to operate the electric motor to drive one or more of the wheels or tracks; in a regenerative mode, using the vehicle's kinetic energy to drive the electric motor to regenerate electrical power; Detect with the controller whether the battery can be further charged in regenerative mode; In response to a determination that the battery should no longer be charged, the controller sends an adjustment command signal to the proportional relief valve connected to the hydraulic system; to adjust the proportional relief valve in response to the adjustment command signal, and to supply a load sensing signal to the load sensing input port of the steering priority valve; and Increasing a standby pressure in the hydraulic system between the pump and the steering priority valve in response to the load sensing signal, thereby increasing a load on the pump to provide a hydraulic load braking function in response to the load sensing signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] For the person skilled in the art, upon reading the following disclosure in conjunction with the accompanying drawings, numerous tasks, features and advantages of the embodiments presented here will be readily apparent. Fig. Figure 1 is a side view of a wheeled backhoe as a battery-powered work vehicle, into which an embodiment of a system and method as disclosed herein is integrated. Fig. Figure 2 is a schematic top view of the mechanical drivetrain of the vehicle. Fig. 1. This diagram shows the architecture with a single electric motor that drives both the gearbox and the hydraulics. However, an architecture with two individual motors is also possible, where separate motors drive the gearbox and the hydraulics. Fig. Figure 3 is a schematic drawing of a control system for the vehicle of Fig. 1. Fig. Figure 4 is a schematic drawing of a section of the vehicle's hydraulic system. Fig. 1. Fig. 5 shows the hydraulic system of Fig. 4 during a normal steering operating mode. Fig. Figure 6 shows the hydraulic system of Fig. 4 during an operating mode without steering with the transmission in standby or in an operating mode without steering with load braking. DETAILED DESCRIPTION

[0011] With reference now to the drawings and in particular to Fig. Figure 1 shows an exemplary self-propelled work vehicle, generally labeled with the number 100. In the specific example used, and for illustrative purposes throughout the detailed description presented here, the vehicle is shown... Fig. 1 a battery-powered backhoe loader 100. The systems disclosed herein may be applicable to similar or otherwise equivalent agricultural, construction, or other vehicles, including, for example, excavators, loaders, graders, and other work machines of the type that typically have one or more work tools for modifying the surrounding terrain. In certain embodiments, the systems and methods disclosed herein may also be applicable to vehicles that do not have direct work tools.

[0012] The work vehicles discussed here typically feature tracked or wheeled propulsion devices that support the chassis on the ground. The backhoe in Fig. Figure 1 has front wheels 112 and rear wheels 114 as propulsion devices. Within the scope of protection of this disclosure, the propulsion devices can be implemented, for example, as belts, steel tracks, or the like in alternative embodiments. In one example of use, an energy storage device 120 selectively supplies direct current (DC) energy to one or more power electronic inverters (not shown), which convert the supplied DC energy into alternating current (AC) energy. The AC energy can be supplied to an AC electric motor 122, which drives the propulsion devices via a transmission 124 to cause the vehicle to propel itself forward on a ground surface. A mechanical drivetrain 126 of the vehicle 100, comprising the electric motor 122 and the transmission 124, is shown in Fig. 2 shown schematically.

[0013] The energy storage device 120 can be generally described herein as a battery unit 120 comprising one or more batteries, or simply as a battery 120. However, the term "battery unit" or "battery," as disclosed herein, can encompass various forms of energy storage, including, for example, supercapacitors, electrolytic capacitors, hybrid capacitors, and the like, which may have different charge and discharge cycles but are otherwise capable of storing sufficient energy to operate the work vehicle 100 in various operating modes over a period of time. The battery unit can be configured to operate with a current charge from 0% to 100% of a maximum charge, preferably sufficient to last for at least an 8-hour workday.In various embodiments disclosed herein, the energy storage device can be the primary power source for driving the propulsion devices 112, 114; however, in alternative embodiments, a hybrid configuration may be within the scope of protection of the present disclosure, in which the energy storage device is selectively used in conjunction with a power-driven AC generator, i.e., at least to assist in operational processes such as the actuation of the propulsion devices, the working equipment and / or other vehicle components.

[0014] The work vehicle 100 comprises an operator's cab 102, which is supported by a machine frame or vehicle frame 110, for housing and protecting the operator of the vehicle. The operator's cab 102 and the one or more work implements 130, 142 can be attached to the vehicle frame 110. The operator's cab can be of numerous conventional forms and may include, for example, one or more user interface devices (not shown), such as a display unit, foot pedals, a steering wheel 104, joysticks, buttons, and any other controls or indicators required for operating the vehicle.

[0015] As previously noted, the work vehicle 100 can comprise one or more work devices, which in the illustrated embodiment are Fig. 1. The working implements are a front-mounted bucket 130 (i.e., loader) and a rear-mounted bucket 142 (i.e., excavator). In alternative embodiments, the working implements may comprise only one of the aforementioned implements or, for example, buckets, shields, rotary tillers, mowers, and the like. The buckets 130 and 142 are movably coupled to the machine frame 110 for working the terrain, e.g., shoveling, transporting, and unloading soil and other materials. The front-mounted bucket 130 may be movably coupled to a front end of the machine frame 110 via a first boom assembly 131, which includes several hydraulic actuators for moving the front-mounted bucket relative to the machine frame. The first boom assembly may include hydraulic lifting cylinders 134 for raising and lowering the first boom assembly and a hydraulic tilting cylinder 136 for tilting (e.g.,The front-mounted bucket can be movably coupled to a rear end of the machine frame via a second boom assembly 140, which includes several hydraulic actuators for moving the rear-mounted bucket relative to the machine frame. The second boom assembly can include, for example, several hydraulic swivel cylinders 144 for pivoting the second boom assembly from side to side, a hydraulic lift or boom cylinder 146 for raising and lowering the second boom assembly, a hydraulic feed cylinder 148 for bending the second boom assembly, and a hydraulic tilt or bucket cylinder 150 for tilting (e.g., for digging and unloading) the rear-mounted bucket. The operator can selectively control the movement of the buckets 130, 142 using controls located in the operator's cab, such as...control one or more of the user interface devices mentioned above.

[0016] The exemplary work vehicle 100 as shown in Fig. 1 can further comprise a right and a left support boom 152 for supporting and stabilizing the work vehicle on the ground, particularly in modes where one or more of the buckets 130, 142 are in operation. Hydraulic lifting or support boom cylinders 154 can be implemented for raising and lowering the support booms 152 relative to the machine frame 110 of the work vehicle.

[0017] In Fig. Figure 2 schematically shows a top view of the mechanical drivetrain 126 of the vehicle 100. The drivetrain 126 comprises the electric motor 122, which is powered by the battery 120 to drive the front and / or rear wheels 112, 114 via the transmission 124. Mechanical power from the transmission 124 can be transmitted to the front wheels 112 via a front axle differential 128 and to the rear wheels 114 via a rear axle differential 133. The transmission 124 can also include a hydraulic pump 132 for supplying hydraulic fluid under pressure to a hydraulic system 156, as shown schematically in Figure 2. Fig. 4-6 drive. The pump 132 is driven directly or indirectly by the electric motor 122. The pump 132 can be a positive displacement pump, for example a gear pump.

[0018] As in Fig. As shown schematically in Figure 4, the hydraulic system 156 of the vehicle 100 comprises the hydraulic pump 132 and a reservoir 158. The hydraulic pump 132 draws hydraulic fluid from the reservoir 158 and supplies pressurized hydraulic fluid to a fluid supply line 160, which transports the high-pressure hydraulic fluid to the various components of the hydraulic system 156. A hydraulic fluid return line 162 returns low-pressure hydraulic fluid to the reservoir 158.

[0019] The hydraulic system 156 includes a steering valve 164, which is configured to direct hydraulic fluid from a connecting line 180, and thus from the fluid supply line 160, to a hydraulic steering actuator 166, which steers the front wheels 112.

[0020] The hydraulic system 156 further includes a steering priority valve 168, which is configured to prioritize the supply of hydraulic fluid from the hydraulic fluid supply line 160 to the steering valve 164. Steering priority valves are well-known hydraulic components designed to ensure that the hydraulic performance requirements of the steering valve 164 are given priority over the requirements of other hydraulic components 170 connected to the hydraulic system 156. This is a safety measure to ensure that the vehicle 100 can always be steered safely.

[0021] The steering valve 164 can be a closed central rotary valve connected to the steering wheel 104. Such a closed central valve does not allow any fluid flow through it when the valve is not activated for steering the vehicle, and thus, when the valve 164 is in a non-activated, i.e., non-steering, mode, it provides a blockage against the hydraulic pressure supplied by the steering priority valve 168 and the pump 132.

[0022] The steering priority valve 168, which is in Fig. As shown schematically in Figure 4, a slide valve can be continuously adjustable between a first position 168a, in which all the hydraulic fluid is directed to the steering valve 164, and a second position 168b, in which all the hydraulic fluid is directed to other hydraulic components 170, which in a backhoe 100 could include the various hydraulic cylinders 134, 136, 144, 146, 148, 150 and 154 discussed above.

[0023] The steering priority valve 168 can include a pressure inlet port 172 connected to a hydraulic fluid supply line 160. A controlled flow outlet port 174 supplies hydraulic fluid to the steering valve 164 via a connecting line 180. An excess flow outlet port 176 supplies any available excess flow beyond the requirements of the steering valve 164 to the other hydraulic components 170 via a connecting line 182. A load sensing inlet port 178 is connected to a load sensing outlet port 184 of the steering valve 164 via a connecting line 186.

[0024] The steering priority valve 168 includes a spool preload spring 169, which determines a minimum pump standby pressure available in the supply line 160 between the pump 132 and the steering priority valve 168. During normal operation of the steering priority valve 168, when the steering valve 164 is not activated and when no load sensing signal is provided by the proportional relief valve 202, as discussed below, the pump standby pressure in the supply line 160 increases when the system is started until it reaches the minimum level determined by the spool preload spring 169, and then the spool moves to position 168b to allow hydraulic fluid to flow from the excess fluid port 176 to the other hydraulic components 170.

[0025] During normal steering operation of the steering valve 164, when such a load-sensing steering priority valve 168 is used, the working pressure generated in the steering valve 164 is present at the load-sensing outlet port 184 of the steering valve 164 and is transmitted to the load-sensing inlet port 178 of the steering priority valve 168. The hydraulic fluid supply line 160 must then supply hydraulic fluid at sufficient pressure to overcome the load-sensing pressure at the load-sensing inlet port 178 as well as the spring pressure of the valve preload spring 169. Thus, if the front wheels 112 are in an environment that results in a strong steering load, this load is detected and priority is given to supplying the necessary hydraulic pressure to the steering valve 164.

[0026] The hydraulic system 156 further comprises a transmission control valve 188, which is defined by the components within the dashed boundary 188, which are shown in Fig. As shown in Figure 4, the transmission control valve 188 is generally configured to control the flow of hydraulic fluid to the various components of the transmission 124 or other related components of the drivetrain 126. The transmission control valve 188 may include a fluid inlet port 190, which is connected to the hydraulic fluid supply line 160, and a fluid outlet port 192, which is connected to the return line 162. A first supply port 194 can provide controlled hydraulic fluid flow to the transmission 124. A second supply port 196 can provide controlled hydraulic fluid flow to the rear axle differential 133. A third supply port 198 can provide controlled hydraulic fluid flow to a hydraulic service brake 200, which is located in Fig. 2 is shown schematically, provide.

[0027] The transmission control valve 188 incorporates an electro-hydraulic proportional relief valve 202. The proportional relief valve 202 includes an inlet 204, which is connected to the hydraulic fluid supply line 160 via a branch line 160a. The proportional relief valve 202 includes an outlet 206, which is connected to the hydraulic fluid return line 162 and thus to the reservoir 158. The inlet 204 is also connected to the load sensing inlet 178 of the steering priority valve 168 via the branch line 160a and the connecting line 186, which are connected at the connection point 208. A check valve 210 is positioned in the connecting line 186 between the proportional relief valve 202 and the steering valve 164 and allows flow from the proportional relief valve 202 to the steering valve 164 and the steering priority valve 168.The check valve 210 also ensures that the load sensing signal at the load sensing input port 178 is not reduced by the proportional relief valve 202 and sent to the reservoir 158.

[0028] As described in more detail below, the proportional relief valve 202 receives control signals 202C from a controller 220. The proportional relief valve 202 is configured so that when it does not receive a command signal from the controller, it discharges any high-pressure fluid from the inlet 204 to the return line 162 and the reservoir 158. However, when the proportional relief valve 202 is closed or partially closed, the pressure reaching the inlet 204, or a portion thereof, is transmitted through the check valve 210 and the connecting line 186 to the load sensing input port 178 of the steering priority valve 168. CONTROL SYSTEM:

[0029] As in Fig. As shown schematically in Figure 3, the work vehicle 100 comprises a control system with a controller 220. The controller can be part of a central control system of the work vehicle, or it can be a separate control module. The controller 220 can include one or more user interface devices, as mentioned above, and can optionally be mounted on a control panel in the operator's cab 102.

[0030] The controller 220 is configured to receive input signals from some or all of the various sensors that together define a sensor system 222. Certain of these sensors may be designed to detect machine operating states or positioning, including, for example, an orientation sensor, sensors of a global positioning system (GPS), vehicle speed sensors 222b, vehicle attachment positioning sensors, and the like. While one or more of these sensors may be discrete, the sensor system may also rely on signals provided by the machine control system.In particular, the sensor system 222, with reference to embodiments of the present disclosure, may further comprise sensors 222a configured to detect a current charge level of the battery unit 120, either collectively or, for example, as individual values ​​for each of several batteries associated with a battery unit 120.

[0031] Likewise, the controller generates 220 control signals to control the operation of various actuators of the vehicle 100. These actuators can include, for example, the various hydraulic cylinders 134, 136, 144, 146, 148, 150 and 154 discussed above.

[0032] The controller 220 comprises a processor 224, a computer-readable medium 226, a database 228, and an input / output module or operator panel 230 with, or associated with, a display 232. An input / output device 234, such as a keyboard, joystick, or other user interface, is provided to allow the operator to input instructions to the controller. The input / output device 234 may be distributed across multiple locations and may include remote input devices for the operator. It is understood that the controller 220 described herein may be a single controller having all of the described functions, or it may comprise multiple controllers with the described functions distributed among the multiple controllers.

[0033] Various operations, steps, or algorithms described in connection with the controller 220 can be implemented directly in hardware, in a computer program product 236, such as a software module executed by the processor 224, or in a combination of both. The computer program product 236 can reside in RAM, flash memory, ROM, EPROM, EEPROM, registers, on a hard disk, a removable disk, or in any other form of computer-readable medium 226 known in the art. An exemplary computer-readable medium 226 can be coupled to the processor 224 so that the processor can read information from and write information to the memory / storage medium. Alternatively, the medium can be integrated into the processor. The processor and the medium can be contained within an application-specific integrated circuit (ASIC).The ASIC can be located in a user terminal device. Alternatively, the processor and the storage medium can be located as discrete components in a user terminal device.

[0034] The term "processor," as used here, can refer to at least general or specific processing devices and / or logic known to those skilled in the art, including, but not limited to, a microprocessor, a microcontroller, a state machine, and the like. A processor can also be implemented as a combination of computing devices, e.g., as a combination of a DSP and a microprocessor, several microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0035] In certain embodiments, data storage in the computer-readable medium 226 and / or in the database 228 may include a database service, cloud databases, or the like. In various embodiments, the computing network may include a cloud server and, in some implementations, may be part of a cloud application, with various functions disclosed herein being distributed between the computing network and other distributed computing devices. Any or all of the distributed computing devices may be implemented as an onboard vehicle control unit and / or server device and / or a desktop computer and / or a laptop computer and / or a smartphone and / or any other electronic device capable of executing instructions. A processor (such as a microprocessor) of the devices may be a general-purpose hardware processor, a specialized hardware processor, or a combination thereof. OPERATING MODES:

[0036] The electric motor 122 can be implemented as a motor / generator, acting as a motor when electrical power is supplied to the motor 122 from the battery 120 to drive the transmission 124 and thus the wheels 112, 114 and the hydraulic pump 132. This is referred to as a drive mode of the motor 122. Conversely, if it is desired to decelerate the vehicle 100, such as when the vehicle 100 is traveling down a slope, the kinetic energy of the vehicle 100 can be transferred from the wheels 112, 114 via the transmission 124 back to the motor 122 to drive the motor as a generator, thereby regenerating electrical energy that is fed back to the battery 120 to recharge it. This is referred to as a regenerative mode of the motor 122. The control unit 220 monitors and controls the flow of electrical energy between the battery 120 and the motor 122.

[0037] As noted, the controller 220 can monitor the charge level of battery 120 via a sensor 222a. The controller 220 can be configured to detect whether battery 120 can be further charged. The controller 220 can also monitor the battery's charging rate. In some cases, if battery 120 is fully charged, too hot, or too cold, and it is desired to brake the vehicle, it may be undesirable to supply more electrical energy to the battery, which would cause it to overcharge and overheat. In this situation, other braking systems may be required.

[0038] Such an additional braking system, which is based on the one in Fig. The system shown in Figures 4-6 is a hydraulic load braking system. A hydraulic load braking system can be provided by increasing the standby pressure in the supply line 160 of the hydraulic system 156, thereby increasing the load on the hydraulic pump 132 and thus the load on the electric motor 122, thereby reducing the electrical energy fed to the battery from the energy generated by the motor 122 in regenerative mode. Such a hydraulic load braking function can be provided by controlling the proportional relief valve 202 of the transmission control valve 188 to send an appropriate load sensing signal back to the load sensing input port 178 of the steering priority valve 168, thereby increasing the pressure in the supply line 160 required to move the spool of the steering priority valve 168.This increased pressure in the supply line 160 increases the load on the pump 132, thereby distributing at least some of the kinetic energy of the moving vehicle 100.

[0039] The controller 220 can be configured to receive an adaptation command signal 202C, as shown in Fig. Figure 3 schematically depicts the system sending a command signal to the electro-hydraulic proportional relief valve 202 to control the closing degree of the proportional relief valve 202. This command signal can be based, at least in part, on the detected charge level and charging rate of battery 120. Normal steering operating mode:

[0040] Fig. 5 schematically represents the system of Fig. Figure 4 represents a normal steering operating mode, in which no adaptation command signal 202C is transmitted to the proportional relief valve 202. As previously described, in this state, the proportional relief valve 202 discharges any high-pressure hydraulic fluid present at the inlet 204 to the hydraulic fluid return line 162 and thus to the reservoir 158, as indicated by arrow 240. In this state, no load sensing signal is sent from the proportional relief valve 202 to the steering priority valve 168. During normal steering operating mode, the only load sensing signal received at the load sensing input port 178 is the load sensing signal from the load sensing outlet port 184 of the steering valve 164, as indicated by arrows 242 and 244. With the gearbox in standby mode (no steering operation):

[0041] Fig. Figure 6 schematically illustrates two different operating modes in which the proportional relief valve 202 is used to generate a load sensing signal that is transmitted to the steering priority valve 168. The first of these modes is referred to as an operating mode "without steering operation with the transmission in standby".

[0042] In Fig. 6. The steering valve 164 is not actuated, and therefore no load sensing signal is generated at the load sensing outlet port 184 of the steering valve 164. It may be desirable to increase the standby pressure of the hydraulic fluid in the hydraulic fluid supply line 160 beyond that which would be present due to the load provided by the other hydraulic components 170. This can be referred to as increasing the pump standby pressure. This can be achieved by sending an adaptation command signal 202C from the controller 220 to the proportional relief valve 202 to instruct a partial closure of the proportional relief valve 202, thereby increasing the pressure at the pressure inlet 204, with the increased pressure being transmitted back as a load sensing signal to the load sensing input port 178 of the steering priority valve 168, as indicated by arrows 246, 248 and 250.This increases the standby pressure in the hydraulic fluid supply line 160. The standby pressure in the hydraulic fluid supply line 160 can be adjusted by changing the adjustment command signal 202C. Without steering operation with load braking function:

[0043] The schematic representation of Fig. 6 also represents an operating mode "without steering operation with load braking function". Again, the steering valve 164 is not actuated, and therefore no load sensing signal is generated at the load sensing outlet port 184 of the steering valve 164.

[0044] If it is desired to distribute the vehicle's kinetic energy 100 via a hydraulic load-braking function to prevent overcharging of the battery 120 in regenerative mode, this can be achieved by sending an adaptation command signal 202C from the controller 220 to the proportional relief valve 202 to instruct a partial closure of the proportional relief valve 202, thereby increasing the pressure at the pressure inlet 204. The increased pressure is transmitted back as a load-sensing signal to the load-sensing input port 178 of the steering priority valve 168, as indicated by arrows 246, 248, and 250. This increases the pressure of the hydraulic fluid in the hydraulic fluid supply line 160 as described above, thereby increasing the load on the pump 132.

[0045] By adjusting the adaptation command signal 202C to the proportional relief valve 202, the magnitude of the load sensing signal sent to the steering priority valve 168 is adjusted, and thus the magnitude of the hydraulic load braking function can be adjusted.

[0046] The controller 220 can be configured to detect the amount of kinetic energy to be distributed from the vehicle 100, for example, by monitoring the vehicle 100's speed using a speed sensor 222b. The controller 220 can then be configured, at least in part, to adjust the adaptation command signal 202C in response to the detected amount of kinetic energy to be distributed, thereby adjusting the hydraulic load-braking function. OPERATING PROCEDURES:

[0047] A procedure for operating vehicle 100 according to the above description may include the following: in a drive mode, using electrical power from the battery 120 to operate the electric motor 122 to drive one or more of the wheels or tracks 112, 114; in a regenerative mode, using the kinetic energy of the vehicle 100 to drive the electric motor 122 to regenerate electrical power; Detect with the controller 220 whether the battery 120 can be further charged in regenerative mode; In response to a determination that the battery 120 should no longer be charged, an adaptation command signal 202C is sent from the controller 220 to the proportional relief valve 202, which is connected to the hydraulic system 156; to adjust the proportional relief valve 202 in response to the adjustment command signal 202C, and to supply a load sensing signal to the load sensing input port 178 of the steering priority valve 168; and Increasing a standby pressure in the hydraulic system between the pump and the steering priority valve in response to the load sensing signal, thereby increasing a load on the pump to provide a hydraulic load braking function in response to the load sensing signal.

[0048] The procedure can further include, in the absence of the adaptation command signal 202C from the control unit 220 to the proportional relief valve 202, releasing hydraulic pressure through the proportional relief valve 202 to the reservoir 158 of the hydraulic system 156, so that no load detection signal is transmitted from the proportional relief valve 202 to the steering priority valve 168.

[0049] The method can further include connecting the load sensing output port 184 of the steering valve 164 to the load sensing input port 178 of the steering priority valve 168, so that the steering priority valve 168 detects a hydraulic pressure required by the steering valve 164 and gives priority to supplying the required hydraulic pressure to the steering valve 164.

[0050] The method may further include transmitting a load sensing signal from the steering valve 164 to the steering priority valve 168 in a normal steering operating mode, wherein no adaptation command signal 202C is transmitted to the proportional relief valve 202 and no load sensing signal is transmitted from the proportional relief valve 202 to the steering priority valve 168.

[0051] The procedure can further include, in an operating mode without steering with the transmission in standby, sending the adaptation command signal 202C to the proportional relief valve 202 to actuate the proportional relief valve 202, transmitting a load sensing signal to the steering priority valve 168 to control a pump standby pressure provided by the hydraulic pump 132.

[0052] The method can further include detecting with the control 220 an amount of the kinetic energy to be distributed of the vehicle 100 and automatically adjusting the adaptation command signal 202C to adapt the hydraulic load braking function at least partly in response to the detected amount of the kinetic energy to be distributed of the vehicle 100.

[0053] It is thus evident that the devices and methods of the present disclosure readily achieve the stated objectives and advantages, as well as those inherent within the disclosure. Although certain preferred embodiments of the disclosure have been illustrated and described for illustrative purposes, the person skilled in the art may make numerous modifications to the arrangement and construction of the parts and steps, such modifications falling within the scope and essence of the present disclosure as defined by the pending claims. Each disclosed feature or embodiment may be combined with one or more of the other disclosed features or embodiments.

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