Work vehicle hydraulic system with fluid exchange reservoir

Abstract

A hydraulic system for a work vehicle has a first hydraulic circuit at a first nominal pressure and a second hydraulic circuit at a second nominal pressure different from the first nominal pressure. A dual-chamber hydraulic reservoir includes a first tank associated with the first hydraulic circuit and defining a first opening and a second tank associated with the second hydraulic circuit and defining a second opening. An exchange system has a particulate filter disposed within an exchange path between the first opening of the first tank and the second opening of the second tank. The exchange system is configured to resupply hydraulic fluid from the second tank to the first tank.

Description

[0001] Cross-reference to related applications

[0002] not applicable.

[0003] Federally funded research or development statement

[0004] not applicable. Technical Field

[0005] This disclosure relates to a hydraulic system for a work vehicle having multiple hydraulic circuits at different hydraulic pressures. Background Technology

[0006] Work vehicles, such as those used in construction, forestry, agriculture, and mining, typically employ hydraulic power to operate their implements, drivetrain components, traction elements, and other operating parts. Hydraulic pumps, motors, accumulators, and control valves provide the hydraulic power required to perform the intended tasks for these operating parts. In some cases (e.g., large hydraulic cylinders for positioning the boom), the demand for hydraulic power is high, while in others (e.g., coolant charge pumps), the demand is relatively low. Power requirements can also vary with operating frequency; some components require hydraulic power continuously, while others require it only intermittently.

[0007] The work vehicle may also employ a charge pump or transmission pump to provide transmission clutch control and lubrication or cooling. Charge pumps typically operate continuously to provide a low-pressure hydraulic fluid flow in a steady-state conduction state; however, when the transmission undergoes frequent gear shifts or changes in forward / reverse direction, the charge pump may need to provide several times higher pressure to support the pressure requirements. Summary of the Invention

[0008] This disclosure provides a hydraulic system for work vehicles, which is an improvement on conventional hydraulic systems by having multiple hydraulic circuits that operate under different pressures.

[0009] In one aspect, this disclosure provides a hydraulic system for a work vehicle, the hydraulic system including a first hydraulic circuit and a second hydraulic circuit, the first hydraulic circuit being at a first nominal pressure and the second hydraulic circuit being at a second nominal pressure different from the first nominal pressure. A dual-chamber hydraulic reservoir includes a first tank and a second tank, the first tank being associated with the first hydraulic circuit and defining a first opening, and the second tank being associated with the second hydraulic circuit and defining a second opening. An exchange system includes a particulate filter disposed within an exchange path between the first opening of the first tank and the second opening of the second tank. The exchange system is configured to resupply hydraulic fluid from the second tank to the first tank.

[0010] In another aspect, this disclosure provides a hydraulic system for a work vehicle, the hydraulic system including a high-pressure hydraulic circuit and a low-pressure hydraulic circuit relative to the high-pressure hydraulic circuit. A dual-chamber hydraulic reservoir includes a first chamber and a second chamber, the first chamber being associated with the high-pressure hydraulic circuit and defining a first opening, and the second chamber being associated with the low-pressure hydraulic circuit and defining a second opening. An exchange system including a particulate filter is disposed within an exchange path between the first opening of the first chamber and the second opening of the second chamber. The exchange system is configured to resupply hydraulic fluid from the second chamber to the first chamber.

[0011] Details of one or more exemplary embodiments are set forth in the accompanying drawings and the following description. Other features and advantages will become apparent from the description, drawings, and claims. Attached Figure Description

[0012] At least one example of this disclosure will be described below in conjunction with the accompanying drawings.

[0013] Figure 1 This is an isometric view of an exemplary work vehicle in the form of a backhoe excavator equipped with a hydraulic system, according to the present disclosure.

[0014] Figure 2 This is a schematic diagram of an exemplary embodiment of a hydraulic system according to the present disclosure;

[0015] Figure 3 Is Figure 2 A simplified isometric view of an exemplary embodiment of a dual-chamber hydraulic reservoir used in an exemplary hydraulic system;

[0016] Figure 4 This is a schematic diagram of another exemplary embodiment of the hydraulic system according to the present disclosure; and

[0017] Figure 5 Is Figure 4A simplified isometric view of another exemplary embodiment of a dual-chamber hydraulic reservoir used in an exemplary hydraulic system.

[0018] The same reference numerals in the various figures denote the same elements. For simplicity and clarity of illustration, descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the exemplary and non-limiting embodiments of the invention described in the following detailed description. It should also be understood that, unless otherwise stated, features or elements appearing in the figures are not necessarily drawn to scale. Detailed Implementation

[0019] Embodiments of the present disclosure are illustrated in the accompanying drawings, which are briefly described above. Those skilled in the art can contemplate various modifications to the exemplary embodiments without departing from the scope of the invention as set forth in the appended claims.

[0020] Overview

[0021] Heavy-duty work vehicles typically use hydraulic power to operate implements, drivetrain components, traction components, and other operating parts. High-load-bearing features, such as loader booms, booms, buckets, and forks, usually require high-pressure hydraulic circuits and hydraulic cylinders, as well as other actuators, to perform a variety of lifting, handling, and digging operations. Other work vehicle components, such as various drivetrain components like transmissions, can operate or be included in control systems that operate at lower pressures. Typically, these components are part of separate hydraulic circuits with low, moderate, or medium control pressures. Other operations, such as cooling or lubrication, can operate at or require even lower pressures. Cooling and / or lubrication circuits can be separate from or independent of other circuits, or in some cases, they can be combined with control pressure circuits. In the latter case, the charge pump typically operates continuously at the control pressure required to support the drivetrain control system. During steady-state operation, the transmission may only require low pressure for cooling and lubrication. When higher pressure demands arise, such as when the transmission undergoes frequent gear shifts or changes in forward / reverse direction, it will require higher control pressure. To serve both functions, the charge pump needs to operate continuously at moderate control pressure, even during periods of low demand. This results in hydraulic system inefficiency because energy is unnecessarily input to components that do not require it during a given operating time, and because that energy could be more efficiently applied to other components of the work vehicle.

[0022] The following describes several different exemplary embodiments of a hydraulic system for a work vehicle that operates more efficiently at multiple hydraulic pressures. Two hydraulic circuits may include a first hydraulic circuit operating at a first nominal pressure and a second hydraulic circuit operating at a second nominal pressure. The first nominal pressure at which the first hydraulic circuit operates may be a high pressure sufficient to operate high-load components of the work vehicle (e.g., lifting, carrying, digging, swinging, braking, etc.). The second nominal pressure at which the second hydraulic circuit operates may be a low pressure sufficient to provide cooling and lubrication for certain components (e.g., transmission). The first hydraulic circuit (e.g., via a pressure regulating structure) may also be used to provide control pressure to one or more features (such as components or devices cooled and / or lubricated by the second hydraulic circuit). In exemplary embodiments, the control pressure may be a moderate pressure sufficient to serve both steady-state operation and high-demand operation of the hydraulic components. It should be noted that the pressure values ​​indicated throughout this disclosure are provided as examples and are not intended as limitations on whether any aspect of the hydraulic system can operate at these pressure values. Compared to a hydraulic system where the hydraulic components have control and cooling / lubrication functions provided by the same circuit, a second hydraulic circuit or low-pressure hydraulic circuit can be implemented with a pump with lower pressure capability (e.g., a low-pressure "lubricating oil" or coolant pump), thereby reducing costs, because the pump with lower pressure capability only needs to provide a low-pressure cooling / lubrication flow, while the control pressure is provided by the high-pressure circuit.

[0023] Exemplary embodiments of the hydraulic system include a dual-chamber hydraulic reservoir with limited and highly filtered fluid exchange to prevent cross-contamination failures that may be caused by normal wear debris, process debris, or usage contamination. The dual-reservoir system allows two hydraulic circuits to operate simultaneously and significantly reduces the risk of cross-contamination. Furthermore, the hydraulic system or the hydraulic reservoir itself includes an exchange system that resupplyes hydraulic fluid from one circuit (e.g., a high-pressure hydraulic circuit) to another circuit (e.g., a low-pressure hydraulic circuit) during operation. Because fluid lost only during control operations (e.g., electromagnetic operation of a clutch mechanism) must be returned to the high-pressure system, fine micron-sized low-flow filters can be used to prevent cross-contamination.

[0024] Two exemplary embodiments of a dual-reservoir hydraulic system are described below. It should be noted that the following examples are described in a non-limiting manner. Other exemplary embodiments may be provided without departing from the scope of the listed claims.

[0025] In a first exemplary embodiment, a static mechanism comprising two tanks connected by a common wall provides hydraulic fluid flow through an exchange system with filters by gravity. The first tank of the two connected tanks contains hydraulic fluid for a first hydraulic circuit that flows to a high-pressure pump, which operates at a first nominal pressure sufficient to support the high-pressure hydraulic functions of the work vehicle. The first hydraulic circuit primarily serves a first hydraulic component, which will be understood as any one of one or more hydraulic devices or actuators generally describing the work vehicle. A portion of the hydraulic fluid flow may be delivered, returned, or otherwise directed (e.g., via flow regulators and accumulators) to a second hydraulic component (e.g., a transmission) to supply hydraulic fluid at a sufficiently high (medium or controlled) pressure to one or more control devices (e.g., one or more electric motors, torque transmitters, etc.) to operate the transmission under steady-state conditions and during high-demand shifting and direction changes. The second tank of the two connected tanks also stores hydraulic fluid for use in a second hydraulic circuit, which includes a low-pressure pump to direct fluid to the transmission (e.g., control devices) for lubrication and cooling functions. During operation of the control unit, hydraulic fluid leaking or flowing out of the first hydraulic circuit within the transmission device flows back to the second tank of the reservoir. An equal volume of hydraulic fluid from the second tank flows back to the first tank via an exchange system located between the two tanks. When replenishing the hydraulic fluid in the first tank, a filter ensures that debris that may be introduced through the transmission device is not transferred to the first tank.

[0026] In the second exemplary embodiment described below, the dual-chamber reservoir may have two tanks that are physically separate and fluidly connected to each other and to an exchange system via hydraulic lines. The exchange system may include a pump for pumping hydraulic fluid from the second (low-pressure) tank to the first (high-pressure) tank. This pump may be a low-capacity (i.e., low-pressure and low-flow) return pump with low power requirements and continuous operation, or it may be a low-capacity transfer pump configured to operate only when triggered by high fluid conditions in the second (low-pressure side) tank of the reservoir or low fluid conditions in the first (high-pressure side) tank of the reservoir.

[0027] Therefore, the hydraulic system for work vehicles disclosed herein has a relatively high-pressure hydraulic circuit that functionally and physically intersects with a relatively low-pressure hydraulic circuit to allow pressure from the high-pressure circuit to perform certain functions that would otherwise require a separate pump or other energy input to the relatively low-pressure circuit. In the following example, the work vehicle is a backhoe loader, where the high-pressure hydraulic circuit is used to operate high-load-capacity components, such as the loader boom and arm, brakes, or other such components. Control devices for other components of the vehicle, such as the motors and torque transmission devices of the aforementioned drivetrain, can be operated by the hydraulic pressure returning from the high-pressure hydraulic circuit. Because the high-pressure hydraulic circuit exceeds the control pressure requirements of the control devices, the drivetrain can be operated without a separate, dedicated charge pump, even under high-demand operating conditions, thus eliminating the associated costs and complexities. Alternatively, only low-pressure and low-cost pumps can be used to cool the control devices and other drivetrain components. To compensate for the loss of hydraulic fluid from the high-pressure circuit during operation of the control devices, this disclosure provides a dual-chamber hydraulic reservoir to transfer a corresponding volume of hydraulic fluid from the low-pressure tank to the high-pressure tank. This exchange is achieved through fine, low-flow micron filters, thereby reducing cross-contamination of the hydraulic circuit, primarily from low-pressure circuits to high-pressure circuits. Various configurations of the dual-chamber hydraulic reservoir include gravity-fed or pump-fed exchange systems, with shared walls or physically separate chambers. The hydraulic system may include pressure sensors or other sensors to detect filter clogging events in the exchange system and provide warning indications to the operator's display in the work vehicle, and / or to perform shutdown operations on the hydraulic circuit, the entire hydraulic system, or the work vehicle.

[0028] Hydraulic system for work vehicles with fluid exchange reservoir

[0029] refer to Figure 1An exemplary working vehicle is shown as a backhoe excavator 20 equipped with a rear excavator assembly 22 and a front loader (FEL) assembly 24, which are mounted to and carried by a chassis 26, which also supports an operator's cab 28. The chassis 26 is supported by a plurality of ground wheels 30, which are driven by a power source via a transmission 32, both of which are carried by the chassis 26 of the backhoe excavator 20. In one or more embodiments, the power source is an internal combustion engine 34, such as a diesel engine, controlled by an engine control module (not shown) of a control system 40 of the backhoe excavator 20. It should be noted that the use of an internal combustion engine is merely an example; the power source could be a fuel cell, an electric motor, a hybrid electric motor, or other power-generating device. The engine 34 selectively drives the wheels 30 to propel the backhoe excavator 20 in a forward or backward direction. Furthermore, the backhoe excavator 20 includes a wheel steering component that includes various devices (e.g., power steering pumps and lines, steering mechanisms, and similar devices) that connect manual (e.g., operator steering controls or wheels) steering inputs and / or (via control system 40) automatic steering inputs to the wheels (e.g., front wheels). In some examples, the operator's cab 28 has a display device 42 and an operator interface 44 (e.g., various control inputs, joysticks, etc.) for controlling the movement of the excavator assembly 22 and the FEL assembly 24. More specifically, the operator can interact with the operator interface 44 to control the movement of the linkages or boom of the excavator assembly 22 and the FEL assembly 24, as well as the orientation of the excavator bucket 48 and the loader bucket 50 articulated to the respective assemblies.

[0030] During operation, the excavator assembly 22 and the FEL assembly 24 are actuated by the extension and retraction of hydraulic cylinders 60, 62, 64, 66, and 68 included in the electro-hydraulic system 70 of the backhoe excavator 20. These hydraulic cylinders include a swing cylinder (not shown) for the excavator assembly 22 and the excavator bucket 48, a boom cylinder (not shown), a stick boom cylinder 60 and an excavator bucket cylinder 62, and a loader boom cylinder 64 (one shown) and loader bucket cylinders 66 and 68 for the FEL assembly 24 and the loader bucket 50. The extension and retraction of the swing cylinder causes the boom 52 (and thus the stick boom 54 and the excavator bucket 48) to rotate relative to the chassis 26 about a vertical axis. The extension and retraction of the boom cylinder causes the boom 52 to rotate about a first pivot joint, at which the boom 52 engages with the chassis 26. The extension and retraction of the boom cylinder 60 causes the boom 54 to rotate about a second pivot joint, at which it engages with the boom 52. The extension and retraction of the excavator bucket cylinder 62 causes the excavator bucket 48 to rotate or "curl" about a third pivot joint, at which it engages with the boom 54. The extension and retraction of the loader boom cylinder 64 causes a pair of loader booms 58 (and therefore the loader bucket 50) to rotate relative to the chassis 26 about a horizontal axis. Finally, the extension and retraction of the loader bucket cylinders 66, 68 causes the loader bucket 50 to rotate or "curl" about a fourth pivot joint, at which it engages with the loader boom 58. Although for clarity... Figure 1 Not shown, the electro-hydraulic system 70 also includes a variety of other hydraulic components, which may include flow lines (e.g., hoses), pumps, manifolds, fittings, safety valves, filters, etc. The electro-hydraulic system 70 may also include a variety of electronic valve actuators and flow control valves such as spool valves, which can be modulated to regulate the flow of pressurized hydraulic fluid into and out of hydraulic cylinders 60, 62, 64, 66, and 68. The flow control valves and possible valve actuators may be combined into one or more control valve assemblies.

[0031] The controller architecture of control system 40 controls the operation of electro-hydraulic system 70, and thereby controls the excavator assembly 22, FEL assembly 24, and other hydraulic components of backhoe excavator 20, such as drive unit 32, as further detailed below. The controller architecture can take any form suitable for performing the control and guidance functions described herein, and is therefore used in a non-limiting sense to generally refer to the processing architecture of control system 40. The controller architecture can therefore encompass or be associated with any actual number of processors (central processing unit and graphics processing unit), individual controllers, computer-readable storage, power supply, storage devices, interface cards, and other standardized components. For example, in many different embodiments, the controller architecture may include a combination of multiple controllers, such as one or more implementation controllers interconnected in an operable manner via a bus or other data communication connection, electro-hydraulic valve controllers, and / or vehicle controllers. The controller architecture may also include any number of firmware and software programs or computer-readable instructions designed to perform the various process tasks, calculations, and control / display functions described herein, or cooperate with such number of firmware and software programs or computer-readable instructions. Such computer-readable instructions can be stored in a non-volatile segment of memory 80 associated with (accessible to) the controller architecture. Although generally in Figure 1 While shown as a single block, the memory 80 can encompass any amount and type of storage medium suitable for storing computer-readable code or instructions, as well as other data used to support the operation of the backhoe excavator 20. The memory 80 can be integrated into the controller architecture of the embodiments, for example as a system-in-package, system-on-a-chip, or another type of microelectronic package or module.

[0032] The control system 40 also includes multiple sensors or sensor arrays 82, such as in Figure 1The sensor array 82 is schematically shown in the upper left corner. It includes various position tracking sensors 84 for tracking the movement and positioning of the excavator and FEL boom and bucket 48 in three-dimensional space. These position tracking sensors 84 may include various rotary position sensors such as rotary variable displacement sensors (RVDTs) or potentiometers, which are incorporated into pivot joints and perhaps directly integrated into structural pins for detecting relative rotational motion. Other sensors may include, for example, linear variable displacement sensors (LVDTs) or other such linear displacement sensors for measuring the stroke of hydraulic cylinders 60, 62, 64, 66, and 68, which can then be converted into angular position values. Additionally or alternatively, MEMS devices such as MEMS accelerometers and gyroscopes packaged as inertial measurement units (IMUs) may be mounted to components of the chassis 26 or excavator assembly 22 and / or FEL assembly 24. Such a MEMS device can then communicate with the controller architecture via a wired or wireless connection to provide acceleration and / or angular displacement data used by the architecture in tracking the motion and position of the buckets 48, 50. In other embodiments, the tracking sensor 84 may include one or more cameras having a field of view encompassing the 3D tool space through which the buckets 48, 50 travel, in which case the controller architecture can track the bucket position via visual analysis fed by the cameras. Finally, as Figure 1 As further shown, the sensor array 82 may also include one or more sensors 86 for monitoring the orientation of the chassis 26, such as MEMS devices mounted to the chassis 26, inclinometers, and similar sensors. In this way, the controller architecture can take into account the orientation of the chassis 26 when tracking the movement of the buckets 48, 50.

[0033] In addition to sensors used to monitor the orientation of chassis 26 and the movement of boom assembly links, sensor array 82 may also include other types of sensors 90. Such other sensors 90 may include one or more sensors that provide data indicating the forces or pressures encountered within the electro-hydraulic system when performing vehicle operations. In some cases, such sensors 90 may directly measure or estimate the load applied to transmission 32 or engine 34. In other cases, such sensors 90 may measure the hydraulic fluid pressure within hydraulic cylinders 60, 62, 64, 66, 68 or the hydraulic fluid pressure within the flow loop network of electro-hydraulic system 70. For example, when performing contamination protection functions, the controller architecture may take into account pressure readings received from pressure sensors 90 or other pressure sensors, as described more fully below.

[0034] As described above, the backhoe excavator 20 has a transmission 32 that transmits power from an engine 34 and / or an electric motor to wheels 30 via rotary motion. The transmission 32 has a gear mechanism that can be controlled to provide a desired mechanical reduction between the engine output and the wheels 30. Typically, to achieve the desired gear ratio, the transmission 32 is functionally coupled to an electro-hydraulic system 70, which distributes pressurized hydraulic fluid through the transmission 32 to one or more control devices (e.g., clutches, torque converters, etc.) via various channels, valves, pumps, filters, etc. The one or more control devices implement gear shifting for multiple forward gear ratios, multiple reverse gear ratios, and forward-reverse direction changes for transmission to the wheels 30. In various different embodiments, the electro-hydraulic system 70 includes one or more electro-hydraulic control valves, such as control valve 120 (see...). Figure 2 The electro-hydraulic control valve may be, for example, an electronically controlled modulating valve (ECMV) that controls one or more clutches, such as clutch 122. The electro-hydraulic control valve can be hydraulically applied or released to serve as one or more control devices for the transmission 32. Typically, control valve 120 senses the fluid pressure in the electro-hydraulic system 70 and measures the hydraulic fluid flow to provide a desired pressure downstream of a hydraulic component with feedback control via the controller architecture of the control system 40. A variety of other types of control valves (e.g., proportional valves, modulating valves, proportional modulating valves, and similar valves) and / or other types of hydraulic components can be used. The controller architecture generates commands for controlling the pressurized hydraulic fluid flow through the electro-hydraulic system 70 by sending command signals to various valves and pumps within the transmission 32. These commands include commands to the exemplary electro-hydraulic control valve 120 for engaging or disengaging clutch 122 and for maintaining a target pressure for actuating clutch 122. Hydraulic control valve 120 is configured, for example, to provide the desired control pressure of hydraulic fluid to clutch 122 as an electro-hydraulic solenoid valve. Hydraulic control valve 120 monitors the pressure in the hydraulic circuit and / or the pressure at clutch 122, and quickly adjusts to maintain optimal clutch performance. One or more pressure sensors, such as sensor 90, may be included within transmission 32 to notify control system 40 and assist in control of transmission 32 by controller architecture.

[0035] In some embodiments, the transmission can be configured to operate in multiple different power modes in the forward and / or reverse travel directions, including, for example, a mechanical-only power mode, a series electric mode, or a split-power mode. In this case, the transmission 32 may be equipped with one or more motors 110 and a gearbox (e.g., a planetary gear set) that provides a continuously variable power flow, and that combines (or adds) the electrical power with the mechanical power from the engine 34, or separately routes the different power configurations passing through the transmission 32. Examples of multi-mode transmission configurations are described in U.S. Patent Nos. 10,647,193, 10,619,711, and 10,670,124, the entire contents of which are incorporated herein by reference, as if fully set forth herein. In such a multi-mode transmission configuration, the motor 110 can therefore be considered one of the control devices for the transmission 32.

[0036] Regardless of whether the transmission 32 has multiple power mode capabilities, the heat-generating and friction components of the transmission 32 can be cooled and lubricated by a pressurized fluid of the same or different type (e.g., viscosity, thermal properties, etc.) as the pressurized fluid used to control the operation of the hydraulic components of the backhoe excavator 20. In some embodiments, the lubricating and / or cooling fluid may be part of the electro-hydraulic system 70. In many different embodiments, the electro-hydraulic system 70 may be used to lubricate and / or cool various components of the backhoe excavator 20, including one or more control devices of the transmission 32, which may include various torque transmission components such as clutch 122 and one or more motors 110 providing multi-mode power transmission.

[0037] Now we will combine Figures 2 to 5 Further details are discussed regarding the electro-hydraulic system 70 deployed on the backhoe excavator 20, in which the cross-pressurization of multiple hydraulic circuits operating at different pressures is advantageously utilized and adapted by a dual-chamber reservoir structure.

[0038] Now for reference Figure 2 and Figure 3 A first exemplary embodiment of the hydraulic circuit structure 200 of the electro-hydraulic system 70 on the backhoe excavator 20 is shown as having a first hydraulic circuit 202 and a second hydraulic circuit 204. The first hydraulic circuit includes hydraulic components and lines, such as various boom cylinders including the boom cylinder 60, the excavator bucket cylinder 62 of the excavator assembly 22, and the loader boom cylinder 64 and loader bucket cylinders 66, 68 of the FEL assembly 24. Because these components can be operatively coupled to the first hydraulic circuit 202, these components... Figure 2The first hydraulic component 236 is schematically represented here. The hydraulic cylinders 60, 62, 64, 66, and 68, as described above, are components of the backhoe excavator 20 that require the highest hydraulic pressure and heavy-duty carrying capacity during operation. While the work implement and its actuation device are described in the exemplary embodiments described herein, it should be understood that other high-load components may alternatively or additionally be part of the first hydraulic circuit 202, including, for example, a variety of different drivetrain components, such as various different hydraulic drives and hydraulic brakes that control the traction and propulsion operations of the backhoe excavator 20. The first hydraulic circuit 202 includes a first hydraulic pump 230 configured to deliver hydraulic fluid at a first nominal pressure to the first hydraulic component 236. The first hydraulic circuit 202 also has a pressure regulator 240 downstream of the first hydraulic component 236, configured to deliver hydraulic fluid at a control pressure to a second hydraulic component 248 of the backhoe excavator 20. A flow control device can be used to implement the pressure regulator 240, which regulates the hydraulic accumulator 242 to control the pressure of the hydraulic fluid downstream of the first hydraulic component 236 and to feed the second hydraulic component 248. In the exemplary embodiment described herein, the second hydraulic component 248 is a transmission device 32 having one or more control devices, such as a control valve 120 that controls the clutch 122.

[0039] The second hydraulic circuit 204 includes a second hydraulic pump 250 configured to deliver hydraulic fluid at a second nominal pressure, different from the first nominal pressure of the first hydraulic circuit 202, to the second hydraulic component 248. The hydraulic fluid in the second hydraulic circuit 204 is used to provide lubrication and cooling fluid at the second nominal pressure to components of the transmission 32, including the motor 110 and the control clutch 122. Other hydraulic components, like the first hydraulic component 236, may alternatively or additionally be part of the second hydraulic circuit 204, such that the described exemplary embodiments or the function of the second hydraulic circuit 204 as providing lubrication and coolant should not be considered as limiting the scope of the disclosed invention. It should also be noted that in the exemplary embodiments described herein, the second hydraulic pump 250 may be a low-pressure, low-capacity, and therefore low-cost pump with any suitable operating configuration, and it should also be noted that the second hydraulic component 248 may omit a dedicated charge pump for operating and controlling the second hydraulic component 248, whether an internal or external charge pump.

[0040] The hydraulic circuit device 200 of the electro-hydraulic system 70 includes a dual-chamber hydraulic reservoir 206 for storing hydraulic fluid (at low pressure or atmospheric pressure) used in the hydraulic circuits 202 and 204. An exemplary dual-chamber hydraulic reservoir 206 is separate from or independent of both the first hydraulic component 236 and the second hydraulic component 248, and includes a first tank 208 and a second tank 210. A first hydraulic pump 230 is in fluid communication with the first tank 208 via a high-pressure line 255, and a second hydraulic pump 250 is in fluid communication with the second tank 210 via a low-pressure line 237. The first tank 208 is configured to supply hydraulic fluid to the first hydraulic circuit 202 with the aid of suction generated by the first hydraulic pump 230, so that the hydraulic fluid flows to the first hydraulic components 236 (e.g., hydraulic cylinders 60, 62, 64, 66, 68 to power the excavator assembly 22 and the FEL assembly 24). The first hydraulic pump 230 supplies hydraulic fluid to the first hydraulic components 236 via a high-pressure line 232. The first hydraulic circuit 202 has a high-pressure return line 235 from the first hydraulic components 236 to return hydraulic fluid to the first tank 208.

[0041] Hydraulic fluid flows from the second tank 210 of the hydraulic reservoir 206 through a low-pressure line 237 to the second hydraulic pump 250, and then to the second hydraulic component 248 for lubrication and cooling. The second hydraulic circuit 204 may also include a cooler 252, which is connected in series with the low-pressure line 237 and between the second hydraulic pump 250 and the second hydraulic component 248, for example. The second hydraulic component 248 may have a collection tank 254 for collecting the hydraulic fluid used for lubrication and cooling, and is connected to the second tank 210 of the hydraulic reservoir 206 via a low-pressure return line 227.

[0042] Cross-feeding device 245 enables the cross-flow and pressurization of hydraulic fluid from the first hydraulic circuit 202 to the second hydraulic circuit 204. This cross-feeding device 245 includes a pressure regulator 240 and a hydraulic accumulator 242. The pressure regulator 240 is fluidly connected to the first hydraulic pump 230 via a high-pressure line 232 and a branch line 234, and thus the cross-feeding device 245 can be considered part of the first hydraulic circuit 202. The pressure regulator 240 is fluidly connected to the hydraulic accumulator 242 and is also fluidly connected to the second hydraulic component 248 via one or more control lines 247. The pressure regulator 240 can be actively controlled by the controller architecture of the control system 40, and it cooperates with the hydraulic accumulator 242 to achieve a control pressure within the control line 247, which is connected to one or more control devices (here, control valve 120 and clutch 122) within the second hydraulic component 248. Therefore, the first hydraulic circuit 202 serves the cross-feed device 245 and thereby the second hydraulic component 248, and during operation of the control device, such as during operation of the control valve 120 and clutch 122 to perform gear ratio changes (i.e., shift events) and / or direction changes as needed, the first hydraulic circuit 202 loses a small but significant volume of hydraulic fluid. Hydraulic fluid may also be lost or transferred from the first hydraulic circuit 202 to the second hydraulic circuit 204 by leaking relatively high-pressure fluid under control pressure into the relatively low-pressure environment within the second hydraulic component 248. This transferred hydraulic fluid can be collected in the collection tank 254 of the second hydraulic component 248. Therefore, the hydraulic fluid returning via the low-pressure return line 227 may include hydraulic oil from the first hydraulic circuit 202 received by the second hydraulic circuit 204. Using the exchange system 220 of the hydraulic reservoir 206, the lost hydraulic fluid or the hydraulic fluid transferred from the first hydraulic circuit 202 to the second hydraulic circuit 204 is returned to the first hydraulic circuit 202.

[0043] The exchange system 220 includes a particulate filter 222 disposed within the exchange path between a first opening 212 in the first tank 208 and a second opening 214 in the second tank 210. The exchange system 220 resupplyes a volume of hydraulic fluid from the second tank 210 to the first tank 208, the volume being approximately equal to the volume of hydraulic fluid transferred from the control pressure to the second nominal pressure within the second hydraulic component 248. Figure 2 and Figure 3In an exemplary embodiment, the hydraulic reservoir 206 has a common wall or shared wall 216, or double walls, which are integrally disposed with and between the first tank 208 and the second tank 210. The exchange system 220 includes an exchange housing 224 that defines an internal volume 226 for accommodating a filter 222. The exchange housing 224 extends across the wall 216 from a second opening 214 in the second tank 210 to a first opening 212 in the first tank 208. Hydraulic fluid flows from the second opening 214 in the second tank 210, through the flow path of the exchange system 220, and enters and passes through the filter 222 within the exchange housing 224. The filtered hydraulic fluid then flows through the first opening 212 and into the first tank 208, thereby replenishing the first hydraulic circuit 202 with the volume lost in the second hydraulic component 248 or transferring the volume to the second hydraulic circuit 204. Figure 2 and Figure 3 In an exemplary embodiment, hydraulic fluid is transported by gravity through the exchange system 220 and its filter 222. When the hydraulic fluid returns to the second tank 210 and fills to a level above the height of the second opening 214, the first tank 208 contains hydraulic fluid at a level below the height of the first opening 212. Because no active control or power-providing components are required for fluid exchange, the exchange system 220 in this exemplary embodiment can be considered a gravity-based or passive system.

[0044] Now for reference Figure 4 and Figure 5 Another exemplary embodiment of providing power to the switching system will be described in detail below. In this exemplary embodiment, the hydraulic circuit device 300 of the electro-hydraulic system 70 includes a first hydraulic circuit 302 and a second hydraulic circuit 304, which can be related to the above description regarding... Figure 2 The first hydraulic circuit 202 and the second hydraulic circuit 204 described in the exemplary embodiments shown are the same, and for clarity, in Figure 4 The components of each loop 302, 304 in the exemplary embodiments are identified using similar or the same reference numerals, and will not be described in detail herein.

[0045] Figure 4The hydraulic circuit device 300 in the embodiment includes a dual-chamber hydraulic reservoir 306 having a first chamber 308 physically separated from the second chamber 310. The first chamber 308 includes a first opening 312 for receiving hydraulic fluid during exchange between the first hydraulic circuit 302 and the second hydraulic circuit 304. The second chamber 310 includes a second opening 314 that substantially defines a gravity discharge port by being positioned at or near the bottom of the chamber. The second opening 314 is connected to an exchange system 320 having an exchange housing 324 physically separated from both chambers 308 and 310, and having an internal volume for accommodating a particulate filter 322. The exchange housing 324 is connected to the openings 312 and 314 of chambers 308 and 310 via low-pressure lines 317 and 319. The exchange system 320 also includes an exchange pump 318, which is connected in series with the filter 322 and via lines 317 and 319 to transfer hydraulic fluid from the second tank 310 through the filter 322 to the first tank 308. The exchange pump 318 can be any suitable low-pressure pump. Due to its low energy consumption, the exchange pump 318 can operate continuously as a scavenge pump, or it can operate either actively and intermittently under the active control of the controller architecture of the control system 40, or passively and intermittently based on the hydraulic fluid level in either tank 308 or 310.

[0046] In the foregoing exemplary embodiments, the nominal pressure and control pressure of the hydraulic circuit operating thereunder can depend on the hydraulic component being operated and the pressure required for its operation. Typically, in the described exemplary embodiments, the nominal pressure of the first hydraulic circuit is high, while the second nominal pressure of the second hydraulic circuit is low relative to the first nominal pressure, and the control pressure is an intermediate pressure between the first and second nominal pressures. In addition to pressure differences, the flow rate and velocity of the hydraulic circuit can also vary, largely depending on the specific hydraulic component involved. In the exemplary embodiments discussed herein, the first nominal pressure has the highest flow rate, followed by the second nominal pressure and then the control pressure. For the purpose of disclosing detailed exemplary embodiments, Figure 2 or Figure 4In this configuration, the first hydraulic pump 230 can operate at a high pressure of about 20 MPa to 35 MPa (i.e., about 3,000 PSI to 5,000 PSI) for a first nominal pressure at a flow rate of about 120 LPM (i.e., about 30 GPM) in the first hydraulic circuit 202; the low-pressure pump 250 can operate at a low pressure of about 0.25 MPa to 0.5 MPa (i.e., about 36 PSI to 72 PSI) for a second nominal pressure at a flow rate of about 40 LPM (i.e., about 10 GPM) in the second hydraulic circuit 204; and the supply pressure can be about 1.75 MPa to 2.5 MPa (i.e., about 250 PSI to 300 PSI) at a flow rate of about 2 LPM to 6 LPM (i.e., about 0.5 GPM to 1.5 GPM). In this context, examples of filters 222 and 324 may be 5-micron to 20-micron particulate filters that allow flow rates of 0.25 LPM to 2 LPM (i.e., about 0.05 GPM to 0.5 GPM), and hydraulic accumulator 242 may be about 3 L to 8 L (i.e., about 0.75 gallons to 2 gallons).

[0047] Therefore, the aforementioned example can be implemented in the electro-hydraulic system 70 to allow cross-pressurization from the higher pressure of the first hydraulic circuit 202, 302 to the lower pressure of the second hydraulic circuit 204, 304 for operating hydraulic components, which would otherwise require separate dedicated hydraulic pumps. The fluid exchange systems 220, 320 of the hydraulic reservoirs 206, 306 ensure that hydraulic fluid lost or transferred from the high-pressure circuits is returned in the same volume. The filtration by the exchange systems 220, 320 reduces or eliminates cross-contamination between hydraulic circuits. To prevent or detect filter clogging, one or more sensors, such as pressure sensor 90 located elsewhere in the exchange systems 220, 320, or any of the hydraulic circuits, can be used to notify the control system 40 of inappropriate pressure conditions. This can trigger the controller architecture to perform one or more of the following: send a notification signal to the operator display device 42; terminate or reduce the demand or output of the electro-hydraulic system 70 (e.g., terminate or reduce pump operation); terminate or impede the operation of other primary users of the work implement or hydraulic power, or terminate or reduce the power system of the backhoe excavator 20 itself.

[0048] Examples of hydraulic systems for work vehicles

[0049] In addition, the following examples are provided, and these examples are numbered for easy reference.

[0050] 1. A hydraulic system for a work vehicle, the hydraulic system comprising: a first hydraulic circuit at a first nominal pressure; a second hydraulic circuit at a second nominal pressure different from the first nominal pressure; a dual-chamber hydraulic reservoir including a first chamber and a second chamber, the first chamber being associated with the first hydraulic circuit and defining a first opening, the second chamber being associated with the second hydraulic circuit and defining a second opening; and an exchange system including a particulate filter disposed within an exchange path between the first opening of the first chamber and the second opening of the second chamber; wherein the exchange system is configured to resupply hydraulic fluid from the second chamber to the first chamber.

[0051] 2. The hydraulic system according to Example 1, wherein the second hydraulic circuit includes a second hydraulic component, the second hydraulic component including one or more hydraulic control devices; wherein, during operation of the one or more hydraulic control devices or during steady-state operation of the second hydraulic component, a volume of hydraulic fluid from the first hydraulic circuit is transferred to the second hydraulic circuit within the second hydraulic component; and wherein the exchange system is configured to resupply the volume of hydraulic fluid from the second tank to the first tank.

[0052] 3. The hydraulic system according to Example 2, wherein the exchange system uses gravity to transfer hydraulic fluid from the second tank through the particulate filter to the first tank.

[0053] 4. The hydraulic system according to Example 3, wherein the reservoir includes an exchange housing that spans the first opening of the first tank and the second opening of the second tank and defines an internal volume that houses the particulate filter and is in fluid communication with the first opening of the first tank and the second opening of the second tank, whereby gravity forces hydraulic fluid from the second tank through the second opening into the internal volume of the exchange housing, through the particulate filter, and through the first opening into the first tank.

[0054] 5. The hydraulic system according to Example 4, wherein the first tank and the second tank are joined together along a common wall, the common wall being disposed between the first opening of the first tank and the second opening of the second tank and being spanned by the exchange housing.

[0055] 6. The hydraulic system according to Example 2, wherein the first tank and the second tank are physically separate structures, and the second opening of the second tank defines a gravity discharge port; wherein the gravity discharge port is connected to the exchange housing containing the particulate filter, and the exchange housing is connected to the first opening of the first tank via a conduit; wherein the exchange system includes an exchange pump for transferring hydraulic fluid from the second tank through the conduit and the particulate filter to the first tank; and wherein the exchange pump is a continuously operating return pump or an intermittently operating transfer pump, the intermittently operating transfer pump being configured to operate according to the level of hydraulic fluid in the first tank or the second tank.

[0056] 7. The hydraulic system according to Example 2, wherein the first hydraulic circuit includes: a first hydraulic pump in fluid communication with the first tank and configured to deliver hydraulic fluid at the first nominal pressure to a first hydraulic component of the work vehicle; and a pressure regulator downstream of the first hydraulic component and configured to deliver hydraulic fluid at a control pressure to one or more control devices of the second hydraulic component; wherein the pressure regulator includes a flow control device that regulates a hydraulic accumulator for delivering hydraulic fluid at the control pressure to one or more control devices of the second hydraulic component; wherein the second hydraulic circuit includes a second hydraulic pump in fluid communication with the second tank and configured to deliver hydraulic fluid at the second nominal pressure to one or more control devices of the second hydraulic component; and wherein the first hydraulic circuit includes a first return line from the first hydraulic component to the first tank, and the second hydraulic circuit includes a second return line from the second hydraulic component to the second tank.

[0057] 8. The hydraulic system according to Example 7, wherein the first nominal pressure is high pressure, the second nominal pressure is low pressure relative to the first nominal pressure, and the control pressure is an intermediate pressure between the first nominal pressure and the second nominal pressure; and wherein the one or more control devices of the second hydraulic component receive hydraulic fluid at a higher flow rate at the second nominal pressure than at the control pressure.

[0058] 9. The hydraulic system according to Example 8, wherein the second hydraulic component is a transmission device, and the one or more control devices include a torque transmission component; wherein the first hydraulic circuit delivers hydraulic fluid at the control pressure to achieve control of the torque transmission component; and wherein the exchange system resupplyes hydraulic fluid from the second tank to the first tank in a manner substantially equal to the volume of hydraulic fluid delivered at the torque transmission component from the control pressure to the second nominal pressure.

[0059] 10. The hydraulic system according to Example 9, wherein the second hydraulic component includes an electric motor; wherein the second hydraulic circuit delivers hydraulic fluid at the second nominal pressure to achieve one or more of cooling and lubrication of the electric motor and the torque transmission component; and wherein the first hydraulic component includes one or more hydraulic cylinders.

[0060] 11. A hydraulic system for a work vehicle, the hydraulic system comprising: a high-pressure hydraulic circuit; a low-pressure hydraulic circuit relative to the high-pressure hydraulic circuit; a dual-chamber hydraulic reservoir including a first chamber and a second chamber, the first chamber being associated with the high-pressure hydraulic circuit and defining a first opening, the second chamber being associated with the low-pressure hydraulic circuit and defining a second opening; and an exchange system including a particulate filter disposed within an exchange path between the first opening of the first chamber and the second opening of the second chamber; wherein the exchange system is configured to resupply hydraulic fluid from the second chamber to the first chamber.

[0061] 12. The hydraulic system according to Example 11, wherein the first hydraulic circuit includes a first hydraulic pump in fluid communication with the first tank and configured to deliver hydraulic fluid at the first nominal pressure to a first hydraulic component of the work vehicle; and wherein the second hydraulic circuit includes a second hydraulic pump in fluid communication with the second tank and configured to deliver hydraulic fluid at the second nominal pressure to one or more control devices of the second hydraulic component.

[0062] 13. The hydraulic system according to Example 12, wherein the first nominal pressure is high pressure, the second nominal pressure is low pressure relative to the first nominal pressure, and the control pressure is an intermediate pressure between the first nominal pressure and the second nominal pressure.

[0063] 14. The hydraulic system according to Example 13, wherein the second hydraulic component is a transmission device, and the one or more control devices include a torque transmission component; wherein the first hydraulic circuit delivers hydraulic fluid at the control pressure to achieve control of the torque transmission component, during which a volume of hydraulic fluid from the first hydraulic circuit is transmitted to the second hydraulic circuit; and wherein the exchange system resupplyes hydraulic fluid from the second tank to the first tank in a manner substantially equal to the volume of hydraulic fluid transmitted from the first hydraulic circuit to the second hydraulic circuit within the second hydraulic component.

[0064] 15. The hydraulic system according to Example 14, wherein the second hydraulic component includes an electric motor; and wherein the second hydraulic circuit delivers hydraulic fluid at the second nominal pressure to achieve one or more of cooling and lubrication of the electric motor and the torque transmission component.

[0065] in conclusion

[0066] Therefore, exemplary embodiments of hydraulic systems for work vehicles have been described, wherein a relatively high-pressure hydraulic circuit functionally and physically intersects with a relatively low-pressure hydraulic circuit to facilitate the transfer of pressure from the high-pressure circuit to perform certain functions that would otherwise require a separate pump or other energy input to the relatively low-pressure circuit. In the foregoing example, the work vehicle is a backhoe loader, where the high-pressure hydraulic circuit is used to operate high-load-capacity components, such as the loader boom and arm, brakes, or other such components. Control devices for other components of the vehicle, such as the motors and torque transmission devices of the aforementioned drivetrain, can be operated by the hydraulic pressure returning from the high-pressure hydraulic circuit. Because the high-pressure hydraulic circuit exceeds the control pressure requirements of the control devices, the drivetrain can be operated without a separate, dedicated charge pump, even under high-demand operating conditions, thus eliminating the associated costs and complexities. Alternatively, only low-pressure and low-cost pumps can be used to cool the control devices and other drivetrain components. To compensate for the loss of hydraulic fluid from the high-pressure circuit during operation of the control devices, this disclosure provides a dual-chamber hydraulic reservoir to transfer a corresponding volume of hydraulic fluid from the low-pressure tank to the high-pressure tank. This exchange is achieved through fine, low-flow micron filters, thereby reducing cross-contamination of the hydraulic circuit, primarily from low-pressure circuits to high-pressure circuits. Various configurations have been described, including gravity-fed or pump-fed exchange systems and dual-chamber hydraulic reservoirs with shared walls or physically separate tanks. Pressure sensors or other sensors can be used to detect filter clogging events in the exchange system and provide warning indications to the operator's display in the work vehicle, and / or to perform degrading or shutdown operations on the hydraulic circuit, the entire hydraulic system, or other components of the work vehicle.

[0067] As used herein, unless the context clearly indicates otherwise, the singular forms of “a,” “an,” “the,” and “the” are also intended to include the plural forms. It will be further understood that when the terms “comprising” and / or “including” are used in this specification, they specify the presence of the stated feature, integer, step, operation, element, and / or component, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0068] The description in this disclosure is presented for illustrative and descriptive purposes and is not intended to be exhaustive or limiting of the disclosure in the form provided. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of this disclosure. The embodiments expressly referenced herein have been selected and described in order to best explain the principles of this disclosure and its practical application, and to enable others skilled in the art to understand this disclosure and recognize the various alternatives, modifications, and variations of the described examples(s). Therefore, many different embodiments and implementations besides those expressly described are also within the scope of the appended claims.

Claims

1. A hydraulic system (70) for a work vehicle (20), the hydraulic system comprising: The first hydraulic circuit (202, 302) is at a first nominal pressure, and the first hydraulic circuit (202, 302) includes a first hydraulic component (236). The second hydraulic circuit (204, 304) is at a second nominal pressure different from the first nominal pressure. The second hydraulic circuit (204, 304) includes a second hydraulic component (248). The second hydraulic component (248) includes one or more hydraulic control devices (120, 122). The second hydraulic component (248) is a transmission device (32). A dual-chamber hydraulic reservoir (206, 306) comprising a first chamber (208, 308) and a second chamber (210, 310), the first chamber (208, 308) being associated with a first hydraulic circuit (202, 302) and defining a first opening (212, 312), and the second chamber (210, 310) being associated with a second hydraulic circuit (204, 304) and defining a second opening (214, 314); and The exchange system (220, 320) includes a particulate filter (222, 322) disposed within the exchange path between the first opening (212, 312) of the first box (208, 308) and the second opening (214, 314) of the second box (210, 310); During steady-state operation of the second hydraulic component (248), a volume of hydraulic fluid from the first hydraulic circuit (202, 302) is transferred to the second hydraulic circuit (204, 304) within the second hydraulic component (248), and the exchange system (220, 320) is configured to resupply hydraulic fluid from the second tank (210, 310) to the first tank (208, 308).

2. The hydraulic system according to claim 1, wherein, The exchange system (220, 320) is configured to resupply the volume of hydraulic fluid from the second tank (210, 310) to the first tank (208, 308).

3. The hydraulic system according to claim 2, wherein, The exchange system (220) uses gravity to transfer hydraulic fluid from the second tank (210) through the particulate filter (222) to the first tank (208).

4. The hydraulic system according to claim 3, wherein, The reservoir (206) includes an exchange housing (224) that spans the first opening (212) of the first container (208) and the second opening (214) of the second container (210) and defines an internal volume (226) that houses the particulate filter (222) and is in fluid communication with the first opening (212) of the first container (208) and the second opening (214) of the second container (210), whereby gravity forces hydraulic fluid from the second container (210) through the second opening (214) into the internal volume (226) of the exchange housing (224), through the particulate filter (222), and through the first opening (212) into the first container (208).

5. The hydraulic system according to claim 4, wherein, The first box (208) and the second box (210) are joined together along a common wall (216) which is disposed between the first opening (212) of the first box (208) and the second opening (214) of the second box (210) and is spanned by the exchange housing (224).

6. The hydraulic system according to claim 2, wherein, The first box (308) and the second box (310) are physically separate structures, and the second opening (314) of the second box (310) defines a gravity discharge port; The gravity discharge port is connected to the exchange housing (324) housing the particulate filter (322), and the exchange housing (324) is connected to the first opening (312) of the first box (308) via conduits (317, 319); and The exchange system (320) includes an exchange pump (318) for transferring hydraulic fluid from the second tank (310) through the conduits (317, 319) and the particulate filter (322) to the first tank (308); and The exchange pump (318) is either a continuously operating return pump or an intermittently operating transfer pump, wherein the intermittently operating transfer pump is configured to operate according to the level of hydraulic fluid in the first tank (308) or the second tank (310).

7. The hydraulic system according to claim 2, wherein, The first hydraulic circuit (202, 302) includes: A first hydraulic pump (230), which is in fluid communication with the first tank (208, 308) and configured to deliver hydraulic fluid at the first nominal pressure to the first hydraulic component (236) of the work vehicle (20); and A pressure regulator (240) is located downstream of the first hydraulic component (236) and is configured to deliver hydraulic fluid at a control pressure to the one or more control devices (120, 122) of the second hydraulic component (248). The pressure regulator (240) is a flow control device that regulates the hydraulic accumulator (242) to deliver hydraulic fluid at the control pressure to the one or more control devices (120, 122) of the second hydraulic component (248). The second hydraulic circuit (204, 304) includes a second hydraulic pump (250) in fluid communication with the second tank (210, 310) and configured to deliver hydraulic fluid at the second nominal pressure to one or more control devices (120, 122) of the second hydraulic component (248); and The first hydraulic circuit (202, 302) includes a first return line (235) from the first hydraulic component (236) to the first tank (208, 308), and the second hydraulic circuit (204, 304) includes a second return line (227) from the second hydraulic component (248) to the second tank (210, 310).

8. The hydraulic system according to claim 7, wherein, The first nominal pressure is high pressure, the second nominal pressure is low pressure relative to the first nominal pressure, and the control pressure is an intermediate pressure between the first nominal pressure and the second nominal pressure; and In this embodiment, one or more control devices (120, 122) of the second hydraulic component (248) receive hydraulic fluid at a higher flow rate than at the control pressure under the second nominal pressure.

9. The hydraulic system according to claim 8, wherein, The one or more control devices (120, 122) include a torque transmission component (122). The first hydraulic circuit (202, 302) supplies hydraulic fluid at the control pressure to control the torque transmission component (122); and The exchange system (220, 320) resupplyes hydraulic fluid from the second tank (210, 310) to the first tank (208, 308), the hydraulic fluid being substantially equal to the volume of hydraulic fluid transmitted from the control pressure to the second nominal pressure at the torque transmission component (122).

10. The hydraulic system according to claim 9, wherein, The second hydraulic component (248) includes a motor (110); and The second hydraulic circuit (204, 304) delivers hydraulic fluid at the second nominal pressure to achieve one or more of the cooling and lubrication of the motor (110) and the torque transmission component (122); and The first hydraulic component (236) includes one or more hydraulic cylinders (60, 62, 64, 66, 68).

11. A hydraulic system (70) for a work vehicle (20), said hydraulic system comprising: High-pressure hydraulic circuits (202, 302), wherein the high-pressure hydraulic circuits (202, 302) include a first hydraulic component (236); The low-pressure hydraulic circuit (204, 304) relative to the high-pressure hydraulic circuit (202, 302) includes a second hydraulic component (248), which includes one or more hydraulic control devices (120, 122) and is a transmission device (32). A dual-chamber hydraulic reservoir (206, 306) comprising a first chamber (208, 308) and a second chamber (210, 310), the first chamber (208, 308) being associated with the high-pressure hydraulic circuit (202, 302) and defining a first opening (212, 312), and the second chamber (210, 310) being associated with the low-pressure hydraulic circuit (204, 304) and defining a second opening (214, 314); and The exchange system (220, 320) includes a particulate filter (222, 322) disposed within the exchange path between the first opening (312, 312) of the first box (208, 308) and the second opening (214, 314) of the second box (210, 310); During steady-state operation of the second hydraulic component (248), a volume of hydraulic fluid from the high-pressure hydraulic circuit (202, 302) is transferred to the low-pressure hydraulic circuit (204, 304) within the second hydraulic component (248), and the exchange system (220, 320) is configured to resupply hydraulic fluid from the second tank (210, 310) to the first tank (208, 308).

12. The hydraulic system according to claim 11, wherein, The high-pressure hydraulic circuit (202, 302) includes a first hydraulic pump (230) which is in fluid communication with the first tank (208, 308) and is configured to deliver hydraulic fluid at a first nominal pressure to the first hydraulic component (236) of the work vehicle (20). The low-pressure hydraulic circuit (204, 304) includes a second hydraulic pump (250) which is in fluid communication with the second tank (210, 310) and is configured to deliver hydraulic fluid at a second nominal pressure to one or more control devices (120, 122) of the second hydraulic component (248).

13. The hydraulic system according to claim 12, wherein, The first nominal pressure is high pressure, the second nominal pressure is low pressure relative to the first nominal pressure, and the control pressure is an intermediate pressure between the first nominal pressure and the second nominal pressure.

14. The hydraulic system according to claim 13, wherein, Furthermore, the one or more control devices (120, 122) include a torque transmission component (122). The high-pressure hydraulic circuits (202, 302) supply hydraulic fluid at the control pressure to control the torque transmission component (122), during which a volume of hydraulic fluid from the high-pressure hydraulic circuits (202, 302) is transferred to the low-pressure hydraulic circuits (204, 304); and The exchange system (220, 320) resupplyes hydraulic fluid from the second tank (210, 310) to the first tank (208, 308), the hydraulic fluid being substantially equal to the volume of hydraulic fluid transferred from the high-pressure hydraulic circuit (202, 302) to the low-pressure hydraulic circuit (204, 304) within the second hydraulic component (248).

15. The hydraulic system according to claim 14, wherein, The second hydraulic component (248) includes a motor (110); and The low-pressure hydraulic circuit (204, 304) delivers hydraulic fluid at the second nominal pressure to achieve one or more of the cooling and lubrication of the motor (110) and the torque transmission component (122).

Images