High-efficiency hydraulic supply system and method for work vehicles

Abstract

A hydraulic supply system provides hydraulic power to functional systems of a work vehicle and includes first and second hydraulic circuits. The first hydraulic circuit includes a first fluid pump operable to produce a first hydraulic fluid; a pressure storage vessel coupled to the first fluid pump; and a first port coupled to the first fluid pump and to the pressure storage vessel, the pressure storage vessel operable to store a reserve hydraulic fluid. The first port delivers pressurized hydraulic fluid from the first circuit for use by the work vehicle, thereby operating the first functional system of the work vehicle. The second hydraulic circuit includes a second fluid pump that produces a second hydraulic fluid, and a second port coupled to the second fluid pump delivers the second hydraulic fluid from the second hydraulic circuit for use by the work vehicle, thereby operating the second functional system of the work vehicle.

Description

Technical Field

[0001] The present disclosure relates to hydraulic systems, and more particularly, to hydraulic supply systems and methods that provide improved efficiency in vehicles. Although described herein as relating to hydraulic supply systems and methods that control a powershift transmission in a tractor and supply lubricating and cooling oil to various driveline components of the tractor transmission, it should be understood that the claimed invention has a much broader range of applications, including, by way of example, use in any type of work vehicle that utilizes a hydraulic supply system for controlling, lubricating, cooling, and / or other functions in the transmission components of the work vehicle. Background Art

[0002] Existing hydraulic supply systems and methods in work vehicles can sometimes be inefficient. This is due in part to the task of supporting the growing range of hydraulic power-consuming systems, and in part to manufacturers' willingness to integrate those power-consuming systems into vehicles to meet customer demand for additional, diverse functionality. Hydraulic supply systems must also be able to support fundamental improvements in vehicle product offerings.

[0003] As an example, a hydraulic supply system that is used to provide high volumes of oil at low continuous pressure to support lubrication and cooling functions in a work vehicle may also be tasked with servicing the periodic low volume, high pressure demands of the power shift control functions of a work vehicle transmission for certain vehicle configuration packages or usage configurations.

[0004] In a background manner. Figure 1 A representative prior art hydraulic supply system 10 is shown to illustrate how these inefficiencies can occur. The hydraulic supply system 10 supplies hydraulic fluid power to a control unit 20 of a powershift transmission 22 of a work vehicle 1. The hydraulic supply system 10 also supplies hydraulic fluid power to one or more lubrication and cooling systems 30 of the work vehicle 1.

[0005] The hydraulic supply system 10 includes a prime mover element such as, for example, a motor 11 driving a pump 12 for supplying hydraulic oil under pressure to a regulator 13 via a supply line 14 including a flow control device such as, for example, a check valve 15 .

[0006] Regulator 13 interfaces pump 12 with controls 20 of a work vehicle's powershift transmission 22 via transmission supply line 23 and also interfaces pump 12 with a set of one or more lubrication and cooling systems 30 of the work vehicle via lubrication supply line 31 .

[0007] In a typical work vehicle application, such as in an agricultural tractor, for example, the controls 20 of a powershift transmission 22 may require a supply of oil delivered at a high pressure to effectuate gear shifting operations in the transmission, but typically only intermittently and for only short periods of time. A nominal example is 30 gallons per minute (GPM) delivered at 300 pounds per square inch (PSI) for approximately 500 ms.

[0008] Also in a typical work vehicle application, such as in an agricultural tractor, for example, lubrication and cooling system 30 may nominally need to deliver oil at a rate of approximately 10 GPM and at a pressure of approximately 45 PSI during operation of the tractor.

[0009] In practice, the pump 12 of the hydraulic supply system 10 must be sized to support the simultaneous demands of both the controls 20 of the powershift transmission 22 and the lubrication and cooling system 30, such as those that may arise during heavy vehicle use when both systems may be operating at full utilization or duty cycle. That is, the pump 12 is typically sized to deliver the sum of the maximum total volume required and also the sum of the maximum total pressure required. In a specific example, the pump 12 is therefore sized to supply approximately 40 GPM at approximately 300 PSI. The regulator 13 regulates this high-volume, high-pressure supply down to the appropriate level as may be locally required by the controls 20 of the powershift transmission 22 and the lubrication and cooling system 30. The regulator drains excess unused oil to the return 16 via the return line 17. Operating the pump 12 in this mode can continuously draw or otherwise consume approximately 5,000 watts of power. Alternatively, the "extra" flow of the high volume pump can be "over-bled" and directed to line 31 to the lubrication and cooling system 30 to lubricate and potentially cool the transmission, thereby removing the need for line 17. There is still a direct energy loss, as this newly pressurized oil, for example at, for example, 300 psi, is now reduced in pressure to, for example, 45 psi, and sent as a low-pressure lubrication and cooling flow to the transmission 22. The energy of the pressure drop is converted to heat in the oil, and therefore additional cooling of the oil may be required.

[0010] In the example, a relatively large displacement, relatively high pressure pump 12 is therefore required. Alternatively, a large variable displacement pump capable of delivering the required sum of pressure and flow may be specified for the application. However, in either case, it may be considered inefficient to provide a hydraulic supply system that is ready to deliver oil at high pressure and high volume when high pressure is only required intermittently and only by a few (in the example, one) fluid consumers. Essentially, in the example, the existing hydraulic supply system 10, including both the pump 12 and the motor 11 sized to drive the pump 12, is generally sized to support peak power loads, even though these peak demands may be relatively short-lived and infrequently experienced, such as may occur during heavy use of the vehicle, such as during gear shifts of the transmission 22.

[0011] Therefore, it would be desirable to provide efficient hydraulic supply systems and methods for supplying hydraulic power to functional systems of an associated work vehicle, such as, for example, a tractor.

[0012] It would further be desirable to provide an efficient hydraulic supply system and method that can simultaneously support both high pressure, low volume hydraulic power consuming loads and low pressure, high volume hydraulic power consuming loads in a work vehicle (eg, a tractor).

[0013] It would be further desirable to provide an efficient hydraulic supply system that can simultaneously support both high-pressure, low-volume hydraulic power consuming loads and low-pressure, high-volume hydraulic power consuming loads in a work vehicle, said efficient hydraulic supply system being relatively smaller and more efficient than existing large-displacement, high-pressure hydraulic supply systems that would otherwise be required to supply hydraulic power to those loads. Summary of the Invention

[0014] Embodiments herein provide efficient hydraulic supply systems and methods for supplying hydraulic power to functional systems of an associated work vehicle, such as, for example, a tractor.

[0015] Embodiments herein further provide efficient hydraulic supply systems and methods that can simultaneously support both high-pressure, low-volume hydraulic power consuming loads and low-pressure, high-volume hydraulic power consuming loads in a work vehicle (eg, a tractor).

[0016] The embodiments herein still further provide an efficient hydraulic supply system that can simultaneously support both high-pressure, low-volume hydraulic power consuming loads and low-pressure, high-volume hydraulic power consuming loads in a work vehicle, and the efficient hydraulic supply system is relatively smaller and more efficient than existing large-displacement, high-pressure hydraulic supply systems that would otherwise be required to supply hydraulic power to those loads.

[0017] In one aspect, a hydraulic supply system operable to provide hydraulic power to functional systems of an associated work vehicle includes first and second hydraulic circuits. The first hydraulic circuit includes a first fluid pump operable to produce a first hydraulic fluid; a pressure storage vessel coupled to the first fluid pump; and a first port coupled to the first fluid pump and to the pressure storage vessel. The pressure storage vessel is operable to store a reserve hydraulic fluid. The first port is operable to deliver pressurized hydraulic fluid from the first circuit for use by the associated work vehicle to operate a first functional system of the work vehicle, wherein the pressurized hydraulic fluid includes a combination of one or more of the first hydraulic fluid and / or the reserve hydraulic fluid. The second hydraulic circuit includes a second fluid pump operable to produce a second hydraulic fluid and a second port coupled to the second fluid pump. The second port is operable to deliver the second hydraulic fluid from the second hydraulic circuit for use by the associated work vehicle to operate a second functional system of the work vehicle.

[0018] In another aspect, the hydraulic supply system further includes a first electric motor coupled to the first fluid pump and a second electric motor coupled to the second fluid pump. The first electric motor is operable to drive the first fluid pump to produce the first hydraulic fluid, and the second electric motor is operable to drive the second fluid pump to produce the second hydraulic fluid for use by the associated work vehicle to operate the second functional system of the work vehicle.

[0019] According to another aspect, the first electric motor drives the first fluid pump independently of the second electric motor.

[0020] According to another aspect, the pressure storage container is a hydraulic accumulator.

[0021] According to another aspect, the hydraulic supply system includes an interface device that operably couples the first fluid pump to an associated drivetrain component of the associated work vehicle, and an electric motor that couples to the second fluid pump. The interface device is operable to drive the first fluid pump to produce the first hydraulic fluid, and the electric motor is operable to drive the second fluid pump to produce the second hydraulic fluid for use by the associated work vehicle to operate the second functional system of the work vehicle.

[0022] According to another aspect, the hydraulic supply system includes: a control system operatively coupled to the first electric motor; and a pressure sensor operatively coupled to the control system. The pressure sensor is operable to sense the pressure of the reserve hydraulic fluid within the accumulator and generate a pressure signal representative of the sensed pressure. The first electric motor drives the first fluid pump in response to a command signal to produce the first hydraulic fluid according to the command signal.

[0023] According to another aspect, the first functional system of the hydraulic supply system includes a shift control for a powershift transmission of the associated work vehicle, and the second functional system of the hydraulic supply system includes a lubrication and cooling system of the associated work vehicle.

[0024] In another aspect, a method for operating a hydraulic supply system provides hydraulic power to a functional system of an associated work vehicle. The method includes generating a first hydraulic fluid by operating a first fluid pump of a first hydraulic circuit of the hydraulic supply system. The method further includes storing a reserve hydraulic fluid in a pressure storage container coupled to the first fluid pump. The method further includes delivering pressurized hydraulic fluid from the first circuit via a first port coupled to the first fluid pump and to the pressure storage container, the pressurized hydraulic fluid from the first circuit being used by the associated work vehicle to operate the first functional system of the work vehicle, wherein the pressurized hydraulic fluid comprises a combination of the first hydraulic fluid and the reserve hydraulic fluid. The method further includes generating a second hydraulic fluid by operating a second fluid pump of a second hydraulic circuit of the hydraulic supply system. The method further includes delivering the second hydraulic fluid via a second port coupled to the second fluid pump, the second hydraulic fluid from the second hydraulic circuit being used by the associated work vehicle to operate the second functional system of the work vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In the accompanying drawings, which are incorporated in and constitute a part of the specification, there are illustrated exemplary embodiments of the invention which, together with the general description of the invention given above and the detailed description given below, serve to illustrate exemplary embodiments of the claimed invention.

[0026] Figure 1 is a schematic diagram illustrating a hydraulic supply system provided in a work vehicle as taught in the art.

[0027] Figure 2 is a schematic diagram illustrating a hydraulic supply system provided in an associated work vehicle according to an exemplary embodiment.

[0028] Figure 3 is a schematic diagram illustrating a hydraulic supply system provided in an associated work vehicle according to an exemplary embodiment.

[0029] Figure 4 is a schematic diagram showing a graph comparing energy-saving efficiency of a hydraulic supply system of an exemplary embodiment with respect to a conventional system.

[0030] Figure 5 is a flowchart illustrating a method of operating a hydraulic supply system according to an exemplary embodiment. DETAILED DESCRIPTION

[0031] One or more exemplary embodiments of the disclosed hydraulic supply system and method for a work vehicle are described below, as illustrated in the accompanying drawings of the figures briefly described above. Various modifications to the exemplary embodiments may be anticipated by those skilled in the art.

[0032] Figure 2 1 is a schematic diagram illustrating a hydraulic supply system 100 provided in an associated work vehicle 1 according to an exemplary embodiment. The hydraulic supply system 100 of the exemplary embodiment supplies hydraulic fluid power to functional systems 19, 29 of the associated work vehicle 1, including, for example, supplying hydraulic fluid power to a first functional system 19 including a control unit 20 that controls shifting of a powershift transmission 22 of the work vehicle 1, and also including supplying hydraulic fluid power to a second functional system 29 of a set of one or more lubrication and cooling systems 30 of the work vehicle 1.

[0033] To this end, hydraulic supply system 100 includes a set of hydraulic circuits, including, in particular, a first hydraulic circuit 110 and a second hydraulic circuit 112, which, according to an exemplary embodiment, are each individually and independently operable to supply hydraulic power to an associated functional system 19, 29 of work vehicle 1. That is, and as shown, first hydraulic circuit 110 supplies hydraulic fluid power to a first functional system 19, which, in the exemplary embodiment, comprises a control 20 of a powershift transmission 22 of work vehicle 1, and second hydraulic circuit 112 supplies hydraulic fluid power to a second functional system 29, which, in the exemplary embodiment, comprises a set of one or more lubrication and cooling systems 30 of work vehicle 1.

[0034] In the example, first hydraulic circuit 110 includes a first fluid pump 120 operable to produce a first hydraulic fluid 122 and a pressure storage vessel 130 coupled to first fluid pump 120. Pressure storage vessel 130 is operable to store a reserve hydraulic fluid 132. According to a particular exemplary embodiment, pressure storage vessel 130 is a hydraulic accumulator 132. First hydraulic circuit 110 further includes a first port 102 coupled to first fluid pump 120 and to pressure storage vessel 130 via a first regulator circuit 140. In the exemplary embodiment, first port 102 is operable to deliver pressurized hydraulic fluid 134 from first circuit 110 for use by an associated work vehicle 1, as may be needed or required to operate a first functional system 19. In the exemplary embodiment, first functional system 19 includes controls 20 of a powershift transmission 22 of work vehicle 1, for example, to periodically shift transmission 22. Pressurized hydraulic fluid 134 comprises a combination of first hydraulic fluid 122 and reserve hydraulic fluid 132 from pressure storage vessel 130. It should be appreciated that, during times when the first pump 120 may be off or otherwise inoperative, the pressurized hydraulic fluid 134 may be formed from or otherwise substantially or entirely comprise the reserve hydraulic fluid 132, with little or no contribution from the first hydraulic fluid 122. It should be further appreciated that, during times when the first pump 120 may be on or otherwise operational and operative, the pressurized hydraulic fluid 134 may be formed from or otherwise substantially primarily comprise the reserve hydraulic fluid 132, with some contribution from the first hydraulic fluid 122.

[0035] A first regulator circuit 140 may be provided in the first hydraulic circuit 110 for providing fluid flow control of the first hydraulic fluid 122 and the reserve hydraulic fluid 132 prior to their mixing to form the pressurized hydraulic fluid 134. The first regulator 140 may include a first pressure regulator device 142 for selectively dumping a portion of the first hydraulic fluid 122 when the first hydraulic fluid 122 exceeds a predetermined selectable set point to regulate the pressure delivered to the first functional system 19 and the pressure storage vessel 130. In the exemplary embodiment, the first functional system 19 includes the control 20 of the powershift transmission 22 of the work vehicle 1. Alternatively, the flow 122 from the first fluid pump 120 may be dumped as an "over-blow" and directed to the lubrication and cooling system 30 to lubricate and potentially cool the transmission 22. A small energy loss may still occur as this newly pressurized oil, for example, at approximately 300 PSI, is now reduced in pressure to approximately 45 PSI, for example, and delivered to the transmission as a low-pressure lubrication and cooling flow for the lubrication and cooling system 30. The energy of the pressure drop is converted into heat in the oil, and thus can benefit from additional cooling of the oil or the like. The first regulator may also include a check valve 144 for preventing hydraulic oil from flowing back toward the first fluid pump 120, and an isolation valve 146 for isolating the pressure storage vessel 130 from the rest of the first hydraulic circuit 110. The isolation valve 146 is normally closed when the vehicle is not in operation and is used to maintain the charge pressure within the vessel even when the vehicle is not in operation (e.g., when in storage, at night, between work shifts, or the like).

[0036] A prime mover or drive element, such as, for example, a first drive unit 170, is operatively coupled to the first fluid pump 120, wherein the first drive unit 170 is operable to drive the first fluid pump 120 to produce the first hydraulic fluid 122. In a particular exemplary embodiment, the first drive unit 170 may be, for example, a first electric motor 172 powered by an electric power source (not shown). In yet another particular exemplary embodiment, described in greater detail below, the first drive unit 170 may include an interface device 174 ( Figure 3 ), the interface device 174 operably couples the first fluid pump 120 to an associated powertrain component of an associated work vehicle, wherein the interface device is operable to drive the first fluid pump 120 to produce the first hydraulic fluid 122.

[0037] The hydraulic supply system 100 of the exemplary embodiment further includes a second hydraulic circuit 112 including a second fluid pump 150 operable to produce a second hydraulic fluid 152 and a second port 104 coupled to the second fluid pump 150 via a second regulator circuit 160. The second port 104 is operable to deliver the second hydraulic fluid 152 from the second hydraulic circuit 112 for use by the associated work vehicle 1 to operate a second functional system 29 of the work vehicle 1. The second hydraulic circuit 112 supplies hydraulic fluid power to the second functional system 29, which, in the exemplary embodiment, includes a set of one or more lubrication and cooling systems 30 of the work vehicle 1.

[0038] A prime mover or drive element, such as, for example, a second drive unit 180, is operatively coupled to the second fluid pump 150, wherein the second drive unit 180 is operable to drive the second fluid pump 150 to produce the second hydraulic fluid 152. In certain example embodiments, the second drive unit 180 may be, for example, a second electric motor 182 powered by an electric power source (not shown).

[0039] As described above, in a typical work vehicle application, such as an agricultural tractor, for example, the controls 20 of the powershift transmission 22 may need to deliver relatively large volumes of oil at relatively high pressures to effectuate gear shifting and other operations within the transmission. However, these demands typically occur only intermittently, and typically only for short periods of time. A nominal example is 30 gallons per minute (GPM), delivered at 300 pounds per square inch (PSI) for approximately 500 milliseconds.

[0040] Also in a typical work vehicle application, such as in an agricultural tractor, for example, lubrication and cooling system 30 may nominally need to deliver oil at a rate of approximately 10 GPM and at a pressure of approximately 45 PSI during operation of the tractor.

[0041] To support the simultaneous demands that may occur on both the controls 20 of the powershift transmission 22 and the lubrication and cooling system 30, such as may occur during heavy vehicle use, the exemplary embodiments described herein utilize a unique set of techniques that, when combined, achieve efficiencies previously unattainable in previous hydraulic supply systems. The first of the exemplary embodiment's unique techniques distributes support responsibility for the controls 20 of the powershift transmission 22 to the first hydraulic circuit 110, and distributes support responsibility for the lubrication and cooling system 30 to the second hydraulic circuit 112. The second of the exemplary embodiment's unique techniques is additive to the first because, rather than simply distributing the 30 GPM, 300 PSI, load of the controls 20 of the powershift transmission 22 to a pump and drive element combination capable of providing 30 GPM at 300 PSI, the exemplary embodiments herein advantageously utilize a hydraulic circuit comprising a small, low-capacity pump combined with a pressure storage vessel (e.g., a hydraulic accumulator). The small, low-capacity pump may be, for example, a pump providing 1 GPM at 300 PSI, and the accumulator may have a capacity of approximately 1 gallon, or approximately 4 liters.

[0042] Thus, for a given load as described in the exemplary embodiment of 30 GPM at 300 PSI and 10 GPM at 45 PSI, rather than requiring a pump and motor combination of approximately 40 GPM at 300 PSI that needs to be driven substantially continuously to support lubrication and other load requirements (e.g., power shifting), the embodiments herein are fully capable of supporting the same load mission, but using only a pair of pumps and corresponding drive units that intermittently provide 1 GPM at 300 PSI and 10 GPM at 45 PSI as needed to support lubrication and load requirements, respectively. Operating in this mode, the pumps 120, 150 of the exemplary embodiment may only draw or otherwise consume approximately 1000 watts of power.

[0043] According to an exemplary embodiment, first electric motor 172 of hydraulic supply system 100 drives first fluid pump 120 independently of second electric motor 182. First electric motor 172 of hydraulic supply system 100 can drive first fluid pump 120 as needed or desired to support operation of first functional system 19 of work vehicle 1. Similarly, second electric motor 182 of hydraulic supply system 100 can drive second fluid pump 150 as needed or desired to support operation of second functional system 29 of work vehicle 1. In the exemplary embodiment, first hydraulic circuit 110 supplies hydraulic fluid power to first functional system 19, which in the exemplary embodiment includes controls 20 of a powershift transmission 22 of work vehicle 1, and second hydraulic circuit 112 supplies hydraulic fluid power to second functional system 29, which in the exemplary embodiment includes a set of one or more lubrication and cooling systems 30 of work vehicle 1.

[0044] In the example, the pressure storage vessel 130 of the hydraulic supply system 100 is an accumulator 132 . The first electric motor 172 drives the first fluid pump 120 independently of the second electric motor 182 to generate pressurized hydraulic fluid 134 by filling the accumulator 132 with the first hydraulic fluid 122 .

[0045] According to an exemplary embodiment, the first electric motor 172 of the hydraulic supply system 100 is operable to drive the first fluid pump 120 according to the pressure level of the reserve hydraulic power in the accumulator, independently of the hydraulic power demand of the first functional system 19 including the shift control 20 of the powershift transmission 22 for the associated work vehicle.

[0046] To provide for the independent operation of the hydraulic circuits 110, 112, a control system 190 may be provided. The control system may be a simple spring-loaded pressure differential switch that is used to regulate the pressure within the accumulator 132, for example, by making or breaking electrical contacts within the control switch. The control system 190 may be an electronic controller (not shown) that includes a processor and a memory storing logic that is executable by the processor to control one or more functions, such as, for example, maintaining the pressure within the accumulator w above a desired set point.

[0047] As shown, a control system 190 is operatively coupled to the first electric motor 172. A pressure sensor 192 is provided that is operatively coupled to the control system 190. The pressure sensor 192 is operable to sense the pressure of the reserve hydraulic fluid within the accumulator 132 and generate a pressure signal 194 representative of the sensed pressure.

[0048] According to an exemplary embodiment, the control system 190 receives the pressure signal 194 and generates a command signal 196 representing the magnitude of the difference between the sensed pressure and a desired pressure set point stored in the control system. The first electric motor 172 responds to the command signal 196 to drive the first fluid pump 120 to produce the first hydraulic fluid 122 according to the command signal 196.

[0049] Figure 3 is a schematic illustration of a hydraulic supply system 300 for use in an associated agricultural tractor work vehicle 2, according to an exemplary embodiment. Referring now to the figure, the portion of the work vehicle shown includes a front axle 3 and a rear axle 4 and a transmission 22, which is coupled to the front axle 3 via a front drive shaft 5 and to the rear axle via a rear drive shaft 6. In the exemplary embodiment, an interface device 174 operably couples a first fluid pump 120 to an associated driveline component 7 of the associated work vehicle 2. The associated driveline component 7 is in turn coupled to a main drive motor 8 of the associated work vehicle 2. The main drive motor can be an electric motor, wherein the exemplary work vehicle 2 can be an "electromotive force" (an electric machine using one or more motor-generator pairs for power). The electric motor 182 is coupled to a second fluid pump 150. Interface device 174 is operable to drive first fluid pump 120 to produce first hydraulic fluid 122 , wherein electric motor 182 is operable to drive second fluid pump 150 to produce second hydraulic fluid 152 for use by associated work vehicle 2 to operate second functional system 29 of the work vehicle.

[0050] In an example, interface device 174 drives first fluid pump 120 via associated drivetrain component 7 of an associated work vehicle independently of electric motor 182 driving second fluid pump 150 .

[0051] Also in the exemplary embodiment, pressure storage vessel 130 of hydraulic supply system 300 includes an accumulator 132 . Interface device 174 drives first fluid pump 120 independently of electric motor 182 to generate pressurized hydraulic fluid 134 by filling accumulator 132 with first hydraulic fluid 122 .

[0052] Figure 4is a schematic illustration of a graph 400 comparing the energy efficiency of the hydraulic supply system of exemplary embodiment A with that of existing system B. As described above with respect to the earlier system, in practice, the pump 12 of the hydraulic supply system 10 must be sized to support the potential simultaneous demands of both the controls 20 of the powershift transmission 22 and the lubrication and cooling system 30, such as might occur during heavy vehicle use when both systems might be operating at full utilization or duty cycle. That is, the pump 12 is typically sized to deliver the sum of the maximum total volume required and also the maximum total pressure required. In a specific example, the pump 12 is therefore sized to supply approximately 40 GPM at approximately 300 PSI. A regulator 13 regulates this high-volume, high-pressure supply down to the appropriate level as might be locally required by the controls 20 of the powershift transmission 22 and the lubrication and cooling system 30. The regulator drains excess unused oil to a return 16 via a return line 17. Alternatively, the "excess" flow of the high-capacity pump can be dumped "over-bleed" and directed to line 31 leading to the lubrication and cooling system 30 to lubricate and potentially cool the transmission, thereby removing the need for line 17. There is still a direct energy loss, as this newly pressurized oil, for example, at, for example, 300 PSI, is now reduced in pressure to, for example, 45 PSI, and sent to the transmission 22 as a low-pressure lubrication and cooling flow. The energy of the pressure drop is converted into heat in the oil, and therefore additional cooling of the oil may be required. Operating in this mode, the pump 12 may draw or otherwise consume approximately 5,000 watts of power. This relatively inefficient power consumption is shown in the figure at 410.

[0053] However, according to the exemplary embodiments herein, for a given load as described in the exemplary embodiment of 30 GPM at 300 PSI and 10 GPM at 45 PSI, rather than requiring a pump and motor combination of approximately 40 GPM at 300 PSI that needs to be driven substantially continuously to support lubrication and other load requirements (e.g., power shifting), the embodiments herein are fully capable of supporting the same load mission, but using only a pair of pumps and corresponding drive units that intermittently provide 1 GPM at 300 PSI and 10 GPM at 45 PSI as needed to meet lubrication and load requirements, respectively. Operating the pumps 120, 150 of the exemplary embodiments in this mode may only draw or otherwise consume approximately 1000 watts of power. This efficient power consumption of the exemplary embodiment is shown in the figure at 420.

[0054] Figure 5is a flow chart illustrating a method 500 for operating a hydraulic supply system according to an exemplary embodiment. Referring now to this figure, before the exemplary embodiments of hydraulic supply systems 100 and 300 are set into operative motion, a pre-operation step 510 sets the system for operation. Pre-operation step 510 includes a step of verifying the pre-charge in the reservoir at step 512. For example, the pre-charge in the accumulator may be nitrogen gas set to a pressure of, for example, approximately 200 to 400 PSI. The work vehicle is then activated at step 514, and isolation valve 146 is operated at step 516 to isolate pressure storage vessel 130 from the rest of first hydraulic circuit 110.

[0055] In step 520, the operating pressure within the accumulator is checked and compared to a minimum value MIN deemed suitable for supporting the hydraulic power demand of the first functional system 19, which comprises the shift control 20 of the powershift transmission 22 of the associated work vehicle. According to an exemplary embodiment, the minimum value MIN deemed suitable for supporting the hydraulic power demand is approximately 300 PSI.

[0056] If the pressure in the accumulator is greater than or equal to the minimum value MIN, the transmission interlock is released in step 560, thereby permitting vehicle operation. Otherwise, the first drive unit 170 operatively coupled to the first fluid pump 120 is activated in step 530 to drive the first fluid pump 120 to produce the first hydraulic fluid 122. In a specific exemplary embodiment, the first drive unit 170 may be, for example, a first electric motor 172 powered by an electric power source (not shown). In another specific exemplary embodiment, which will be described in more detail below, the first drive unit 170 may include an interface device 174 ( Figure 3 ), the interface device 174 operably couples the first fluid pump 120 to an associated powertrain component of an associated work vehicle, wherein the interface device is operable to drive the first fluid pump 120 to produce the first hydraulic fluid 122.

[0057] In step 540, it is checked again whether the pressure in the accumulator has reached the maximum set point value MAX. If the pressure in the accumulator is greater than or equal to the maximum value MAX, then in step 550, if the first drive unit 170 is the clutch 174 ( Figure 3 ), the first drive unit 170 operatively coupled to the first fluid pump 120 is disconnected, or if the first drive unit 170 is an electric motor 172 ( Figure 2), the first drive unit 170 operatively coupled to the first fluid pump 120 is stopped. Thereafter, the transmission interlock is released in step 560, thereby permitting vehicle operation. Alternatively, the flow of a small, low-volume pump can be dumped "over-release" and directed to the lubrication and cooling system 30 to lubricate and potentially cool the transmission 22. Additionally, the first drive unit 170 can be or otherwise include a vehicle internal combustion engine that is directly coupled to the first fluid pump 120 to consistently generate pressure and flow of the first hydraulic fluid 122 during operation. Since the pump is a low-volume, low-energy-demand pump, the energy required will be less than, for example, 1000 watts.

[0058] Unless the context clearly indicates otherwise, as used herein, the singular forms "a," "an," and "the" are intended to include the plural meaning. In addition, the terms "comprises" and / or "includes" and similar phrases are intended to specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0059] Although the present disclosure has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description are not restrictive in nature, and it should be understood that (one or more) illustrative embodiments have been shown and described, and it is desired to protect all changes and modifications that fall within the spirit of the present disclosure. Alternative embodiments of the present disclosure may not include all of the features described, but still benefit from at least some of the advantages of such features. Those of ordinary skill in the art can design their own embodiments that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the appended claims.

Claims

1. A hydraulic supply system (100) operable to provide hydraulic power to functional systems (19, 29) of an associated work vehicle (1), the hydraulic supply system (100) comprising: A first hydraulic circuit (110), the first hydraulic circuit comprising: a first fluid pump (120) operable to produce a first hydraulic fluid (122); a pressure storage vessel (130) coupled to the first fluid pump (120), the pressure storage vessel (130) being operable to store a reserve of hydraulic fluid; and a first port (102) coupled to the first fluid pump (120) and the pressure storage vessel (130), the first port (102) being operable to deliver pressurized hydraulic fluid (134) from the first hydraulic circuit (110) for use by the associated work vehicle (1) to operate a first functional system (19) of the work vehicle (1), wherein the pressurized hydraulic fluid (134) comprises a combination of the first hydraulic fluid (122) and the reserve hydraulic fluid; and A second hydraulic circuit (112), the second hydraulic circuit comprising: a second fluid pump (150) operable to produce a second hydraulic fluid (152); and A second port (104) is coupled to the second fluid pump (150), the second port (104) being operable to deliver the second hydraulic fluid (152) from the second hydraulic circuit (112) for use by the associated work vehicle (1) to operate a second functional system (29) of the work vehicle (1).

2. The hydraulic supply system (100) according to claim 1, further comprising: a first electric motor (172), the first electric motor being coupled to the first fluid pump (120); and a second electric motor (182), the second electric motor being coupled to the second fluid pump (150), wherein the first electric motor (172) is operable to drive the first fluid pump (120) to generate the first hydraulic fluid (122), The second electric motor (182) is operable to drive the second fluid pump (150) to generate the second hydraulic fluid (152) for use by the associated work vehicle to operate the second functional system (29) of the work vehicle.

3. The hydraulic supply system according to claim 2, wherein: The first electric motor (172) drives the first fluid pump (120) independently of the second electric motor (182).

4. The hydraulic supply system according to claim 3, wherein: The pressure storage vessel (130) includes an accumulator; and The first electric motor (172) drives the first fluid pump (120) independently of the second electric motor (182) to generate the pressurized hydraulic fluid (134) by filling the accumulator with the first hydraulic fluid (122).

5. The hydraulic supply system according to claim 4, wherein: The first electric motor (172) is operable to drive the first fluid pump (120) independently of the hydraulic power demand of the first functional system (19) and in accordance with the pressure level of the reserve hydraulic power in the accumulator.

6. The hydraulic supply system according to claim 5, wherein: The first functional system (19) includes a shift control (20) for a powershift transmission (22) of the associated work vehicle (1); and The second functional system (29) comprises a lubrication and cooling system (30) of the associated work vehicle (1).

7. The hydraulic supply system according to claim 4, further comprising: a control system (190) operatively coupled to the first electric motor (172); and a pressure sensor (192) operatively coupled to the control system (190), the pressure sensor (192) operable to sense the pressure of the reserve hydraulic fluid within the accumulator and to generate a pressure signal (194) representative of the sensed pressure, wherein the control system (190) receives the pressure signal (194) and generates a command signal (196) representing the magnitude of the difference between the sensed pressure and a desired pressure set point stored in the control system, The first electric motor (172) drives the first fluid pump (120) in response to the command signal (196) to generate the first hydraulic fluid (122) according to the command signal (196).

8. The hydraulic supply system according to claim 1, further comprising: an interface device (174) operatively coupling the first fluid pump (120) to an associated drivetrain component of the associated work vehicle; and an electric motor coupled to a second fluid pump (150), wherein the interface device (174) is operable to drive the first fluid pump (120) to produce the first hydraulic fluid (122), The electric motor is operable to drive the second fluid pump (150) to generate the second hydraulic fluid (152) for use by the associated work vehicle (1) to operate the second functional system (29) of the associated work vehicle (1).

9. The hydraulic supply system according to claim 8, wherein: The interface device (174) drives the first fluid pump (120) through the associated drivetrain component of the associated work vehicle independently of the electric motor driving the second fluid pump (150).

10. The hydraulic supply system according to claim 9, wherein: The pressure storage vessel (130) includes an accumulator; and The interface device (174) drives the first fluid pump (120) independently of the electric motor to generate the pressurized hydraulic fluid (134) by filling the accumulator with the first hydraulic fluid (122).

11. The hydraulic supply system according to claim 10, wherein: The first functional system (19) includes a shift control (20) for a powershift transmission (22) of the associated work vehicle (1); and The second functional system (29) comprises a lubrication and cooling system (30) of the associated work vehicle (1).

12. A method of operating a hydraulic supply system (100) to provide hydraulic power to a functional system (19, 29) of an associated work vehicle (1), the method comprising: generating a first hydraulic fluid (122) by operating a first fluid pump (120) of a first hydraulic circuit (110) of the hydraulic supply system (100); storing a reserve hydraulic fluid in a pressure storage container (130) coupled to the first fluid pump (120); delivering pressurized hydraulic fluid (134) from the first hydraulic circuit (110) via a first port (102) coupled to the first fluid pump (120) and to the pressure storage container (130), the pressurized hydraulic fluid (134) from the first hydraulic circuit (110) being used by the associated work vehicle (1) to operate a first functional system (19) of the work vehicle (1), wherein the pressurized hydraulic fluid (134) comprises a combination of the first hydraulic fluid (122) and the reserve hydraulic fluid; generating a second hydraulic fluid (152) by operating a second fluid pump (150) of a second hydraulic circuit (112) of the hydraulic supply system (100); and The second hydraulic fluid (152) is delivered via a second port (104) coupled to the second fluid pump (150), and the second hydraulic fluid (152) from the second hydraulic circuit (112) is used by the associated work vehicle (1) to operate a second functional system (29) of the work vehicle (1).

13. The method according to claim 12, wherein: Generating the first hydraulic fluid includes generating a low volume of 1 gallon per minute and a high pressure of 300 psi; and Generating the second hydraulic fluid includes generating a high volume of 10 gallons per minute and a low pressure of 45 psi.

14. The method according to claim 12, wherein: Generating the first hydraulic fluid includes driving a first fluid pump using a first electric motor; and Generating the second hydraulic fluid includes driving a second fluid pump using a second electric motor, The first electric motor drives the first fluid pump independently of the second electric motor to generate the pressurized hydraulic fluid by filling an accumulator with the first hydraulic fluid.

15. The method of claim 12, wherein: driving the first fluid pump via an interface device that operably couples the first fluid pump with an associated drivetrain component of the associated work vehicle; The second fluid pump is driven by an electric motor coupled to the second fluid pump to generate the second hydraulic fluid for use by the associated work vehicle (1) to operate the second functional system of the associated work vehicle.

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