Patent Publication Number: US-11378104-B1

Title: Flow management of a hydraulic system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     N/A 
     FIELD OF THE DISCLOSURE 
     The present disclosure relates to flow management of a hydraulic system for a work vehicle. 
     BACKGROUND 
     Work vehicles can include a hydraulic system with one or more variable displacement hydraulic pumps. The hydraulic system can provide hydraulic flow to various implements attached or connected to the work vehicle. The hydraulic flow can be proportional to the engine speed of the work vehicle. The numbers and sizes of the hydraulic pumps for the hydraulic system can be determined by the amount of hydraulic flow available at the lowest operating engine speed. 
     Current tractor hydraulic systems include variable displacement, pressure and flow compensated (PFC) hydraulic pumps providing hydraulic flow to implements through individual selective control valves (SCVs). The maximum flow provided by each pump is proportional to engine speed. As engine speed decreases, for example at an end-row turn, the available hydraulic flow to the implement is reduced, which can lead to reduced implement performance. Some tractor hydraulic systems include an additional pump operating at a lower margin pressure level than the standard pump, but this additional pump continuously operates at elevated pressure levels due to the load signal from the implement even when additional flow is not needed. This leads to increased pump flow leakages and results in increased parasitic power losses when additional flow is not required. 
     SUMMARY 
     This summary is provided to introduce a selection of concepts that are further described below in the detailed description and accompanying drawings. This summary is not intended to identify key or essential features of the appended claims, nor is it intended to be used as an aid in determining the scope of the appended claims. 
     The present disclosure includes a hydraulic system having a plurality of hydraulic pumps for providing hydraulic flow to an implement attached or connected to a work vehicle. 
     According to an aspect of the present disclosure, a hydraulic system for a work vehicle including a first pump providing a first flow in a first circuit to a first plurality of selective control valves. The first pump has a first swashplate. A first load sense circuit connects to a first load sensing compensator of the first pump. A first pressure sensor measures a first pressure in the first circuit. A first swashplate angle sensor measures a first angle of the first swashplate. A supplemental pump provides a supplemental flow to a supplemental circuit. The supplemental pump has a supplemental swashplate. The supplemental pump operates at a lower flow in a standby condition and a higher flow in a use condition. A supplemental load sense circuit connects to a supplemental load sensing compensator of the supplemental pump. A supplemental pressure sensor measures a supplemental pressure in the supplemental circuit. A supplemental valve adjusts a load sensing signal, a load sensing pressure, or a load sensing flow provided to the supplemental load sensing compensator. A first valve selectively enables flow from the supplemental circuit to the first circuit when the supplemental pressure is equal to or greater than the first pressure. A controller determines to operate the supplemental pump in one of the standby condition and the use condition based in part on the first angle of the first swashplate. 
     According to an aspect of the present disclosure, the controller determines to operate the supplemental pump in the standby condition when the first angle of the first swashplate is below a displacement threshold. 
     According to an aspect of the present disclosure, the controller determines to operate the supplemental pump in the use condition when the first angle of the first swashplate is at or above a displacement threshold. 
     According to an aspect of the present disclosure, the controller operates the supplemental valve in a first position to provide a minimal load sense pressure to the supplemental load sensing compensator in the standby condition, which causes the supplemental pump to provide the lower flow. 
     According to an aspect of the present disclosure, the controller operates the supplemental valve in a second position to provide an increased or higher load sense pressure to the supplemental load sensing compensator in the use condition, which causes the supplemental pump to provide the higher flow. 
     According to an aspect of the present disclosure, supplemental valve connects the supplemental load sense circuit to a sump in a first position. 
     According to an aspect of the present disclosure, supplemental valve connects the supplemental load sense circuit to the supplemental circuit in the second position. 
     According to an aspect of the present disclosure, the supplemental valve connects the supplemental load sense circuit to the first load sense circuit in the second position. 
     According to an aspect of the present disclosure, the controller operates the first valve in an open position when the supplemental pressure is equal to or greater than the first pressure. 
     According to an aspect of the present disclosure, the first circuit connects to an associated first implement hydraulic circuit via the first plurality of selective control valves. 
     According to an aspect of the present disclosure, a method of providing supplemental flow for a hydraulic system of a work vehicle including: operating a first pump to provide a first flow in a first circuit to a first plurality of selective control valves; adjusting a first swashplate of the first pump via a first load sense circuit connected to the first pump; measuring a first pressure of the first circuit via a first pressure sensor; measuring a first angle of the first swashplate of the first pump via a first swashplate angle sensor; operating the supplemental pump to provide a lower flow in a standby condition and a higher flow in a use condition to a supplemental circuit; adjusting a supplemental swashplate of the supplemental pump via a supplemental load sense circuit connected to a supplemental load sensing compensator of the supplemental pump; measuring a supplemental pressure in the supplemental circuit via a supplemental pressure sensor; adjusting a load sensing signal, a load sensing pressure, or a load sensing flow provided to the supplemental load sensing compensator via a supplemental valve; selectively enabling flow from the supplemental circuit to the first circuit via a first valve when the supplemental pressure is equal to or greater than the first pressure; and determining via a controller to operate the supplemental pump in one of the standby condition and the use condition based in part on the first angle of the first swashplate. 
     According to an aspect of the present disclosure, determining via a controller includes operating the supplemental pump in the standby condition when the first angle of the first swashplate is below a displacement threshold. 
     According to an aspect of the present disclosure, determining via a controller includes operating the supplemental pump in the use condition when first angle of the first swashplate is at or above a displacement threshold. 
     According to an aspect of the present disclosure, the method further includes operating the supplemental valve in a first position via the controller to provide a minimal load sense pressure to the supplemental load sensing compensator in the standby condition, which causes the supplemental pump to provide the lower flow. 
     According to an aspect of the present disclosure, the method further includes operating the supplemental valve in a second position via the controller to provide an increased or higher load sense pressure to the supplemental load sensing compensator in the use condition, which causes the supplemental pump to provide the higher flow. 
     According to an aspect of the present disclosure, the controller operates the supplemental valve in the first position when the first angle of the first swashplate is below a displacement threshold. 
     According to an aspect of the present disclosure, the controller operates the supplemental valve in the second position when the first angle of the first swashplate is at or above a displacement threshold. 
     According to an aspect of the present disclosure, the method further includes connecting the supplemental load sense circuit to the supplemental circuit when the supplemental valve is in the second position. 
     According to an aspect of the present disclosure, the method further includes connecting the supplemental load sense circuit to the first load sense circuit when the supplemental valve is in the second position. 
     According to an aspect of the present disclosure, selectively enabling flow from the supplemental circuit to the first circuit via a first valve includes operating the first valve in an open position via the controller when the supplemental pressure is equal to or greater than the first pressure. 
     These and other features will become apparent from the following detailed description and accompanying drawings, wherein various features are shown and described by way of illustration. The present disclosure is capable of other and different configurations and its several details are capable of modification in various other respects, all without departing from the scope of the present disclosure. Accordingly, the detailed description and accompanying drawings are to be regarded as illustrative in nature and not as restrictive or limiting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description of the drawings refers to the accompanying figures in which: 
         FIG. 1  is a perspective view of a work vehicle, according to an implementation; 
         FIG. 2  is a schematic diagram of a hydraulic system for a work vehicle, according to an implementation; 
         FIG. 3  is a schematic diagram of a hydraulic system for a work vehicle, according to an implementation; 
         FIG. 4  is a schematic diagram of a hydraulic system for a work vehicle, according to an implementation; 
         FIG. 5  is a schematic diagram of a hydraulic system for a work vehicle, according to an implementation; 
         FIG. 6  is a schematic diagram of a hydraulic system for a work vehicle, according to an implementation; 
         FIG. 7  is a schematic diagram of a hydraulic system for a work vehicle, according to an implementation; 
         FIG. 8  is a schematic diagram of a hydraulic system for a work vehicle, according to an implementation; 
         FIG. 9  is a flow diagram of a hydraulic system for a work vehicle, according to an implementation; and 
         FIG. 10  is a flow diagram of a hydraulic system for a work vehicle, according to an implementation. 
     
    
    
     Like reference numerals are used to indicate like elements throughout the several figures. 
     DETAILED DESCRIPTION 
     The implementations disclosed in the above drawings and the following detailed description are not intended to be exhaustive or to limit the disclosure to these implementations. Rather, there are several variations and modifications which may be made without departing from the scope of the present disclosure. 
     Those having ordinary skill in the art will recognize that terms such as “above,” “below,” “upward,” “downward,” “top,” “bottom,” etc., are used descriptively for the figures, and do not represent limitations on the scope of the disclosure, as defined by the appended claims. Furthermore, the teachings may be described herein in terms of functional and/or logical block components and/or various processing steps, which may be comprised of any number of hardware, software, and/or firmware components configured to perform the specified functions. 
     Terms of degree, such as “generally,” “substantially,” or “approximately” are understood by those having ordinary skill in the art to refer to reasonable ranges outside of a given value or orientation, for example, general tolerances or positional relationships associated with manufacturing, assembly, and use of the described implementations. 
       FIG. 1  illustrates an agricultural work vehicle  100 , for example an agricultural tractor. This disclosure also applies to other types of work vehicles in agriculture, construction, forestry, and road building. The agricultural work vehicle  100 , hereinafter referred to as a work vehicle  100 , can include a frame or chassis  110 , an operator station or cab  102 , and one or more ground engaging apparatus  106 , for example wheels or track assemblies. The work vehicle  100  can have a rigid or an articulated frame  110 . The work vehicle  100  can include a power source  108  positioned under a covering or hood  104  and a transmission transferring power to the ground engaging apparatus  106 , hereinafter referred to as wheels  106 , and one or more power take off shafts. The work vehicle  100  can include an operator interface having any number and combination of electronic devices, such as an interactive display. The work vehicle  100  can include a hydraulic system  120 , which can be connected or coupled to a hydraulic system  114  of an implement  112  having one or more implement hydraulic circuits  116 ,  118 . 
     With reference to  FIGS. 2 and 3 , a hydraulic system  120  of the work vehicle  100  can be connected to the hydraulic system  114  of the implement  112  via one or more sets of individual selective control valves (SCVs)  138 ,  148 . Each set of SCVs  138 ,  148  can include one or more SCVs. In any of the implementations for any of the FIGURES, the hydraulic system  120  can include one or more of a first circuit  122 , a second circuit  124 , and a supplemental circuit  126  in any combination. In some implementations, the hydraulic system  120  can include a first circuit  122  and a supplemental circuit  126 . In other implementations, the hydraulic system  120  can include a first circuit  122 , a second circuit  124 , and a supplemental circuit  126 . The first and second circuits  122 ,  124  can be the primary hydraulic circuits for providing hydraulic fluid flow to first and second implement hydraulic circuits  116 ,  118 . The supplemental circuit  126  can provide additional or supplemental hydraulic fluid flow to the first circuit  122 , the second circuit  124 , or both. In some implementations, the first circuit  122  can be connected to a first implement hydraulic circuit  116  via a first set of SCVs  138 . Alternatively, or additionally, the second circuit  124  can be connected to a second implement hydraulic circuit  118  via a second set of SCVs  148 . 
     The first circuit  122  can include a first pump  130  having a first swashplate  132  and a flow or load sensing compensator  136  connected to a first load sense circuit  134 , which provides pressure feedback to adjust an angle of the first swashplate  132 . The first circuit  122  can provide hydraulic fluid flow to the first set of SCVs  138 . The second circuit  124  can include a second pump  140  having a second swashplate  142  and a flow or load sensing compensator  146  connected to a second load sense circuit  144 , which provides pressure feedback to adjust an angle of the second swashplate  142 . The second circuit  124  can provide hydraulic fluid flow to the second set of SCVs  148 . The supplemental circuit  126  can include a supplemental pump  150  having a supplemental swashplate  152  and a flow or load sensing compensator  156  connected to a supplemental load sense circuit  154 , which provides pressure feedback to adjust an angle of the supplemental swashplate  152 . The first and second pumps  130 ,  140  can be the primary pumps for the first and second circuits  122 ,  124 . The first, second, and supplemental pumps  130 ,  140 ,  150  can be driven directly or indirectly from the power source  108  of the work vehicle  100 , such as an internal combustion engine. 
     The first, second, and supplemental pumps  130 ,  140 ,  150  can be pressure and flow compensated variable displacement (PFC) pumps, each connected to the same or different sumps  128 . In some implementations, the first, second, and supplemental pumps  130 ,  140 ,  150  are pressure and flow compensated variable displacement axial piston pumps, each having a pressure compensator to limit the maximum system pressure and a flow or load sensing compensator  136 ,  146 ,  156  to maintain a predetermined load pressure differential between the outlet port of the pump  130 ,  140 ,  150  and the pressure of the load sense circuit  134 ,  144 ,  154 . The predetermined load pressure differential is determined by a fixed or adjustable differential spring in the load sensing compensator  136 ,  146 ,  156 . Each flow or load sensing compensator  136 ,  146 ,  156  adjusts the swashplate to maintain the predetermined load pressure differential. Each pressure compensator adjusts the swashplate of the pump to limit the maximum operating pressure at the outlet port of the pump. 
     The first load sense circuit  134  can be connected to the first circuit  122 . The second load sense circuit  144  can be connected to the second circuit  124 . The supplemental load sense circuit  154  can be connected to the supplemental circuit  126  via a fixed or variable flow control valve or flow restrictor  174 . The supplemental load sense circuit  154  can include a first supplemental valve  170 , such as an adjustable pressure reducing or pressure reducing and relieving valve connected to a sump  128 . A controller  200 , described in more detail below, can control the first supplemental valve  170  to provide a desired load sense signal or pressure to the supplemental pump  150  via the supplemental load sense circuit  154 . The controller  200  can control the first supplemental valve  170  in an open position so that a reduced or minimal load sense signal or pressure provided to the supplemental load sensing compensator  156  causes the supplemental pump  150  to operate at a reduced or minimal flow. The minimal load sense signal or pressure can be zero or near zero. The minimal flow can be a no-flow or nearly no-flow condition. The controller  200  can control the first supplemental valve  170  in a closed position so that an increased load sense signal or pressure provided to the supplemental load sensing compensator  156  causes the supplemental pump  150  to increase flow. The controller  200  can control the first supplemental valve  170  between the open and closed positions to vary the flow of the supplemental pump  150  so that the pressure in the supplemental circuit  126  is equal to or greater than the pressure in either the first circuit  122  or second circuit  124 , depending on whether the first circuit  122  or second circuit  124  requires additional flow. The supplemental pump  150  can operate in a standby condition with a lower or minimal flow at a lower pressure or a use condition with a higher flow at a higher pressure. 
     The supplemental circuit  126  can provide additional or supplemental flow to the first circuit  122  via a first valve  160 , which can be an adjustable or variable two-position valve with an open or flow control position and a closed position, as shown in  FIG. 2 . The first valve  160  can be a directional control valve or proportional directional control valve. When the first valve  160  is in the open position, fluid can flow from the supplemental circuit  126  to the first circuit  122 . When the first valve  160  is in the closed position, fluid is prevented from flowing from the supplemental circuit  126  to the first circuit  122 . When the first valve  160  is a partially open position between fully open and closed, fluid can flow from the supplemental circuit  126  to the first circuit  122  in a limited or restricted manner. 
     Alternatively, or additionally, the supplemental circuit  126  can provide additional or supplemental flow to the second circuit  124  via a second valve  162 , which can be an adjustable or variable two-position valve with an open or flow control position and a closed position, as shown in  FIG. 3 . The second valve  162  can be a directional control valve or proportional directional control valve. When the second valve  162  is in the open position, fluid can flow from the supplemental circuit  126  to the second circuit  124 . When the second valve  162  is in the closed position, fluid is prevented from flowing from the supplemental circuit  126  to the second circuit  124 . When the second valve  162  is in a partially open position between open and closed, fluid can flow from the supplemental circuit  126  to the second circuit  124  in a limited or restricted manner. 
     With reference to  FIG. 4 , the hydraulic system  120  includes similar components as the hydraulic system  120  in  FIG. 3 , except as shown or described. In some implementations, the supplemental load sense circuit  154  can be connected to the supplemental circuit  126  via a first supplemental valve  170 , such as a three-way, two position directional control valve or a proportional directional control valve. The first supplemental valve  170  includes a first position connecting the supplemental load sense circuit  154  to the sump  128  and a second position connecting the supplemental circuit  126  to the supplemental load sense circuit  154 . The first supplemental valve  170  can be a pressure reducing or pressure reducing and relieving valve. The pressure reducing line can include a fixed or variable flow control valve or flow restrictor  174 . The supplemental circuit  126  can be connected to the first circuit  122  via the first valve  160 . Alternatively, or additionally, the supplemental circuit  126  can be connected to the second circuit  124  via the second valve  162 . 
     With reference to  FIG. 5 , the hydraulic system  120  includes similar components as the hydraulic system  120  in  FIG. 4 , except as shown or described. In some implementations, the first and second valves  160 ,  162  are check valves. The supplemental circuit  126  can be connected to the first circuit  122  via the first check valve  160 . Alternatively, or additionally, the supplemental circuit  126  can be connected to the second circuit  124  via the second check valve  162 . The first and second check valves  160 ,  162  can have any cracking pressure. In one example, the check valves can have a cracking pressure between one and ten bar. In another example, the check valves can have a cracking pressure between three and seven bar. In another example, the check valves can have a cracking pressure around five bar. 
     With reference to  FIG. 6 , the hydraulic system  120  includes similar components as the hydraulic system in  FIG. 2 , except as shown or described. In some implementations, the first valve  160  is a check valve positioned between the supplemental circuit  126  and the first circuit  122 . The supplemental load sense circuit  154  is connected to the first load sense circuit  134  via a first supplemental valve  170 , such as a three-way, two position directional control valve or a proportional directional control valve. The first supplemental valve  170  includes a first position connecting the supplemental load sense circuit  154  to the sump  128  and a second position connecting the supplemental load sense circuit  154  to the first load sense circuit  134 . The hydraulic system  120  can include a first filter  192  positioned on one side of the first supplemental valve  170  and a second filter  194  positioned on the other side of the first supplemental valve  170 . 
     In some implementations, the hydraulic system  120  in  FIG. 6  can include a second valve  162 , such as a check valve as shown for example in  FIG. 5 , positioned between the supplemental circuit  126  and the second circuit  124 . The hydraulic system  120  can include an intermediate valve  190  connected to the first load sense circuit  134 , the second load sense circuit  144 , and the supplemental load sense circuit  154 , as shown for example in  FIG. 7 . Any of the intermediate valves described herein can be a shuttle valve, a flow divider and combiner valve, or any other type of flow combiner valve. The intermediate valve  190  can be positioned between the first load sense circuit  134  and the first supplemental valve  170  and between the second load sense circuit  144  and the first supplemental valve  170 , as shown for example in  FIG. 7 . With the intermediate valve  190 , either the first load sense circuit  134  or the second load sense circuit  144  can be connected to the load sensing compensator  156  of the supplemental pump  150 . 
     In other implementations, the supplemental load sense circuit  154  in  FIG. 6  can be connected to the second load sense circuit  144  via a second supplemental valve  180 , such as a three-way, two position directional control valve or a proportional directional control valve as shown for example in  FIG. 8 . The second supplemental valve  180  includes a first position connecting the supplemental load sense circuit  154  to the sump  128  and a second position connecting the supplemental load sense circuit  154  to the second load sense circuit  144 . The hydraulic system  120  can include one or more filters positioned on either side or on both sides of the second supplemental valve  180 . The hydraulic system  120  can include an intermediate valve  190  positioned between the first supplemental valve  170  and the supplemental pump  150  and between the second supplemental valve  180  and the supplemental pump  150 , as shown for example in  FIG. 8 . With the intermediate valve  190 , either the outlet of the first supplemental valve  170  or the outlet of the second supplemental valve  180  can be connected to the load sensing compensator  156  of the supplemental pump  150 . 
     With reference to  FIG. 7 , the hydraulic system  120  includes similar components as the hydraulic system in  FIG. 5 , except as shown or described. In some implementations, the supplemental load sense circuit  154  can connect to the first load sense circuit  134 , the second load sense circuit  144 , or both instead of the supplemental circuit  126 . The supplemental circuit  126  can connect to the first circuit  122 , the second circuit  124 , or to both. An intermediate valve  190  can connect the supplemental load sense circuit  154  to the first load sense circuit  134  or second load sense circuit  144  depending on whether the first load sense circuit  134  or the second load sense circuit  144  has the higher pressure. The supplemental load sense circuit  154  can include a first supplemental valve  170  positioned between the intermediate valve  190  and the supplemental pump  150 . The first supplemental valve  170  can be an adjustable or variable two-way, two-position valve with an open or flow control position and a closed position. The first supplemental valve  170  can be a directional control valve or a proportional directional control valve. The first supplemental valve  170  can control the fluid flow between the intermediate valve  190  and the supplemental pump  150 . In some implementations, the intermediate valve  190  is a shuttle valve, a flow divider and combiner valve, or any other type of flow combiner valve. 
     With reference to  FIG. 8 , the hydraulic system  120  includes similar components as the hydraulic system in  FIG. 7 , except as shown or described. In some implementations, the supplemental load sense circuit  154  is connected to the first load sense circuit  134  via a first supplemental valve  170 , such as a three-way, two position directional control valve or a proportional directional control valve. The first supplemental valve  170  can include a first position connecting the supplemental load sense circuit  154  to the sump  128  and a second position connecting the first load sense circuit  134  to the supplemental load sense circuit  154 . The first supplemental valve  170  can include a first pilot line  172  connected to the first circuit  122  via a fixed or variable flow control valve or flow restrictor  174 , a second pilot line  176  connected to the first load sense circuit  134 , and a first spring  171  biasing the first supplemental valve  170  in the first position. When the pressure in the first pilot line  172  combined with the first spring  171  force is equal to or greater than the pressure in the second pilot line  176 , the first supplemental valve  170  moves to or remains in the first position. When the pressure in the second pilot line  176  is equal to or greater than the pressure in the first pilot line  172  combined with the first spring  171  force, the first supplemental valve  170  moves to or remains in the second position. 
     The supplemental load sense circuit  154  is connected to the second load sense circuit  144  via a second supplemental valve  180 , such as a three-way, two position directional control valve or a proportional directional control valve. The second supplemental valve  180  can include a first position connecting the supplemental load sense circuit  154  to the sump  128  and a second position connecting the second load sense circuit  144  to the supplemental load sense circuit  154 . The second supplemental valve  180  can include a third pilot line  182  connected to the second circuit  124  via a fixed or variable flow control valve or flow restrictor  184 , a fourth pilot line  186  connected to the second load sense circuit  144 , and a second spring  181  biasing the second supplemental valve  180  in the first position. When the pressure in the third pilot line  182  combined with the second spring  181  force is equal to or greater than the pressure in the fourth pilot line  186 , the second supplemental valve  180  moves to or remains in the first position. When the pressure in the fourth pilot line  186  is equal to or greater than the pressure in the third pilot line  182  combined with the second spring  181  force, the second supplemental valve  180  moves to or remains in the second position. 
     The supplemental circuit  126  can connect to the first circuit  122 , the second circuit  124 , or to both. A first intermediate line  178  can connect the first supplemental valve  170  to an intermediate valve  190  and a second intermediate line  188  can connect the second supplemental valve  180  to the intermediate valve  190 . The intermediate valve  190  can connect the first intermediate line  178  or the second intermediate line  188  to the load sensing compensator  156  depending on whether the first intermediate line  178  or the second intermediate line  188  has the higher pressure. Alternatively, the first supplemental valve  170 , the second supplemental valve  180 , or both, can connect directly or through another valve to the load sensing compensator  156  of the supplemental pump  150 . Any of the circuits described herein can include one or more lines, connections, or components. 
     With reference to  FIGS. 1-8 , the work vehicle  100  can include an electronic control unit or controller  200 . The implement  112  can optionally include an electronic control unit, or controller  220 . The controllers  200 ,  220  can be connected via an electrical connector  218 . The following description of a controller applies to any of the controllers  200 ,  220  in the work vehicle  100  or implement  112 . The controller can have one or more microprocessor-based electronic control units or controllers, which perform calculations and comparisons and execute instructions. The controller includes a processor, a core, volatile and non-volatile memory, digital and analog inputs, and digital and analog outputs. The controller can include non-transitory, computer readable memory, such as random-access memory (RAM), read only memory (ROM), or electrically erasable programmable read only memory (EEPROM), which include instructions for execution by the processor. The controller connects to and communicates with various input and output devices including, but not limited to, switches, relays, solenoids, actuators, light emitting diodes (LED&#39;s), passive and interactive displays, radio frequency devices (RFD&#39;s), sensors, and other controllers. The controller receives communications or signals, via electrically or any suitable electromagnetic communication, from one or more devices, determines an appropriate response or action, and sends communications or signals to one or more devices. The controller can be a microprocessor, an application specific integrated circuit (ASIC), a digital processor, or a programmable logic controller, also known as a PLC or programmable controller. The controller can connect to and communicate with an electronic control system of the work vehicle  100 , the implement  112 , or both through a data bus, such as a CAN bus, or the controller can be a part the electronic control system of the work vehicle  100 , the implement  112 , or both. 
     The hydraulic system  120  can include a variety of sensors to detect or measure pressure, flow, load, and other properties of the hydraulic system  120 . The hydraulic system  120  can include a first swashplate angle sensor  202  to detect or measure the angle of the swashplate  132  of the first pump  130 , a second swashplate angle sensor  204  to detect or measure the angle of the swashplate  142  of the second pump  140 , and a supplemental swashplate angle sensor  206  to detect or measure the angle of the swashplate  152  of the supplemental pump  150 . The hydraulic system  120  can include a first pressure sensor  208  to detect or measure the pressure in the first circuit  122 , a second pressure sensor  210  to detect or measure the pressure in the second circuit  124 , and a supplemental pressure sensor  212  to detect or measure the pressure in the supplemental circuit  126 . The first pressure sensor  208  can detect or measure the pressure at or near the outlet of the first pump  130 . The second pressure sensor  210  can detect or measure the pressure at or near the outlet of the second pump  140 . The supplemental pressure sensor  212  can detect or measure the pressure at or near the supplemental pump  150 . 
     The controller  200  can connect to and communicate with the controller  220 , the sensors  202 ,  204 ,  206 ,  208 ,  210 ,  212 , the valves  160 ,  162 ,  170 , and other electronic devices on the work vehicle  100  or implement  112 . The controller  200  can determine the angle of the swashplate  132  of the first pump  130  from the first swashplate angle sensor  202 , the angle of the swashplate  142  of the second pump  140  from the second swashplate angle sensor  204 , and the angle of the swashplate  152  of the supplemental pump  150  from the supplemental swashplate angle sensor  206 . The controller  200  can determine the pressure in the first circuit  122  from the first pressure sensor  208 , the pressure in the second circuit  124  from the second pressure sensor  210 , and the pressure in the supplemental circuit  126  from the supplemental pressure sensor  212 . The controller  200  can determine to operate the valves  160 ,  162 ,  170 ,  180  in their various positions based in part on the information provided by the sensors  202 ,  204 ,  206 ,  208 ,  210 ,  212 . 
     During operation of the work vehicle  100  connected to an implement  112 , the first circuit  122  is connected to the first implement hydraulic circuit  116  via a first set of SCVs  138 . Alternatively, or additionally, the second circuit  124  is connected to the second implement hydraulic circuit  118  via a second set of SCVs  148 . The supplemental circuit  126  can be connected to the first circuit  122 , the second circuit  124 , or both. The supplemental circuit  126  can provide additional or supplemental flow to the first circuit  122 , the second circuit  124 , or both. The supplemental pump  150  can produce the additional flow requested or required by one or more of the first circuit  122  and the second circuit  124 . The supplemental pump  150  can operate in a standby condition at a lower pressure or a use condition at a higher pressure. 
     The hydraulic system  120  can predict or determine when additional flow will be needed or required to maintain the performance of the first circuit  122 , the second circuit  124 , or both. The hydraulic system  120  measures the pressure and flow of the first pump  130 , the second  140 , or both to predict or determine when the additional flow will be needed. The supplemental pump  150  operates at a more efficient low pressure standby when additional flow is not requested or required by the first circuit  122  or the second circuit  124 . When the hydraulic system  120  predicts or determines additional flow is requested or required, the hydraulic system  120  energizes the supplemental pump  150  to provide additional flow to the first circuit  122 , the second circuit  124 , or both. When the hydraulic system  120  predicts or determines the additional flow is no longer required, the hydraulic system  120  returns the supplemental pump  150  to the low pressure standby. In systems in which one or more pumps supply fluid to a single set of SCVs, the supplemental pump  150  can provide additional flow to supplement the one or more pumps. In systems in which a plurality of pumps each supply fluid to separate SCVs, the supplemental pump  150  can provide additional flow to any of or all the plurality of pumps simultaneously. 
     The controller  200  can determine to operate the supplemental pump  150  in the standby condition until additional flow is requested or required. In the standby condition, the supplemental load sense circuit  154  provides a reduced or minimal load sense pressure to the load sense compensator  156  causing the supplemental pump  150  to provide a lower or minimal flow to the supplemental circuit  126 . The supplemental swashplate  152  operates at or near the minimum displacement angle in the standby condition. According to some implementations, the controller  200  can control the supplemental valve  170  to adjust or maintain the pressure in the supplemental load sense circuit  154 . The controller  200  can control the supplemental valve  170  to maintain the reduced or minimal load sense pressure in the supplemental load sense circuit  154  when in the standby condition, as shown in  FIGS. 2-7 . The controller  200  can control the supplemental valve  170  to maintain a zero or near zero pressure in the supplemental load sense circuit  154  when in the standby condition, as shown in  FIGS. 2-7 . 
     According to the implementation in  FIG. 8 , the controller  200  can control the operation or position of one or more of the first supplemental valve  170 , the second supplemental valve  180 , and the intermediate valve  190 . Alternatively, or additionally, the pressure differential between the first circuit  122  and the first load sense circuit  134  can control the position of the first supplemental valve  170 . For example, the pressure differential between the first circuit  122  and the first load sense circuit  134  can directly or indirectly move or maintain the first supplemental valve  170  in the first position, the second position, or any position between the first and second positions. Alternatively, or additionally, the pressure differential between the second circuit  124  and the second load sense circuit  144  controls the position of the second supplemental valve  180 . For example, the pressure differential between the second circuit  124  and the second load sense circuit  144  can directly or indirectly move or maintain the first supplemental valve  170  in the first position, the second position, or any position between the first and second positions. 
     When the first supplemental valve  170  is in the first position, the supplemental circuit  126  operates at a lower pressure in the standby condition. When the first supplemental valve  170  is in the second position, then the pressure from the first load sense circuit  134  connects to the load sensing compensator  156  of the supplemental pump  150 . When both the first circuit  122  and the second circuit  124  are connected to the supplemental circuit  126 , the supplemental circuit  126  operates at a lower pressure in the standby condition when both the first supplemental valve  170  and the second supplemental valve  180  are in the first position. When one of or both the first supplemental valve  170  and the second supplemental valve  180  are in the second position, then the intermediate valve  190  allows one of the first load sense circuit  134  and the second load sense circuit  144  to connect to the load sensing compensator  156  based on whether the first load sense circuit  134  or the second load sense circuit  144  has the higher pressure. 
     The controller  200  can determine when additional or supplemental flow is required by the first circuit  122 , the second circuit  124 , or both. For example, the controller  200  can determine when additional flow is required by the first circuit  122  based in part on one or more of a pressure of the first circuit  122  measured by the first pressure sensor  208  and an angle of the first swashplate  132  of the first pump  130  measured by the first swashplate angle sensor  202 . The controller  200  can determine additional flow is required when the angle of the first swashplate  132  is at or above a displacement threshold as measured by the first swashplate angle sensor  202 . Alternatively, or additionally, the controller  200  can determine additional flow is required when the angle of the second swashplate  142  is at or above a displacement threshold as measured by the second swashplate angle sensor  204 . 
     The first swashplate  132  can vary between a minimum displacement angle and a maximum displacement angle. The minimum displacement angle can be a zero or near zero displacement angle. The maximum displacement angle can be at or near the maximum angle for the swashplate of the pump. The displacement threshold can be a predetermined percentage of the maximum displacement angle of the first swashplate  132 . The displacement threshold can be at or near the maximum displacement angle of the first swashplate  132 . The pressure in the first circuit  122  can vary based in part on the load of the first circuit  122 . The pressure threshold can be at or near a preselected maximum pressure. 
     If the controller  200  determines additional flow is required, then the controller  200  can operate the supplemental pump  150  in the use condition. The controller  200  can control the position of the first supplemental valve  170  to increase the load sense pressure in the supplemental load sense circuit  154  connected to the load sensing compensator  156 . The increased or higher load sense pressure provided to the load sensing compensator  156  causes the displacement angle of the supplemental swashplate  152  to increase greater than the minimum displacement angle. The supplemental pump  150  increases flow in the supplemental circuit  126 , which causes the pressure to increase in the supplemental circuit  126  as measured by the supplemental pressure sensor  212 . 
     The controller  200  can adjust or vary the pressure reducing valve  170  to prevent the supplemental load sense circuit  154  from dumping to the sump  128 , which increases the load sense pressure in the supplemental load sense circuit  154 , as shown in  FIGS. 2 and 3 . The controller  200  can move the proportional directional control valve  170  to the second position connecting the supplemental circuit  126  to the supplemental load sense circuit  154  and increasing the load sense pressure in the supplemental load sense circuit  154 , as shown in  FIGS. 4 and 5 . 
     The controller  200  can move the proportional directional control valve  170  to the second position connecting the first load sense circuit  134  to the supplemental load sense circuit  154 , as shown in  FIG. 6 . The connection to the first load sense circuit  134  increases the load sense pressure provided to the load sensing compensator  156  via the supplemental load sense circuit  154 . The increased or higher load sense pressure provided to the load sensing compensator  156  causes the supplemental pump  150  to increase flow in the supplemental circuit  126 , which results in an increased or higher pressure in the supplemental circuit  126 . The supplemental swashplate  152  operates between the minimum and maximum displacement angles based upon the pressure differential between the load sense pressure in the supplemental load sense circuit  154  provided to the load sensing compensator  156  and the pressure in the supplemental circuit  126 . 
     The controller  200  can move the proportional directional control valve  170  to the second position connecting the supplemental circuit  126  to either the first load sense circuit  134  or the second load sense circuit  144  via the intermediate valve  190  based on whether the first load sense circuit  134  or the second load sense circuit  144  has the higher pressure, as shown in  FIG. 7 . The connection to either the first load sense circuit  134  or the second load sense circuit  144  increases the pressure provided to the load sensing compensator  156  via the supplemental load sense circuit  154 . 
     According to the implementation in  FIG. 8 , the pressure differential between the first circuit  122  and the first load sense circuit  134  can move the first supplemental valve  170  to the second position. Alternatively, or additionally, the pressure differential between the second circuit  124  and the second load sense circuit  144  can move the second supplemental valve  180  to the second position. The intermediate valve  190  can connect either the pressure of the first load sense circuit  134  or the second load sense circuit  144  to the supplemental load sense circuit  154  based on whether the first intermediate line  178  from the first supplemental valve  170  or the second intermediate line  188  from the second supplemental valve  180  has the higher pressure. This connection to either the first load sense circuit  134  or the second load sense circuit  144  increases the pressure provided to the load sensing compensator  156  via the supplemental load sense circuit  154 , which causes the supplemental pump  150  to increase the flow in the supplemental circuit  126 . 
     When the pressure in the supplemental circuit  126  increases to a higher pressure equal to or greater than the first circuit  122 , the supplemental circuit  126  can provide additional flow to the first circuit  122  via the first valve  160 , to the second circuit  124  via the second valve  162 , or to both the first and second circuits  122 ,  124 . When the first valve  160  is a directional control valve or proportional directional control valve, the controller  200  can open or partially open the first valve  160  after the pressure in the supplemental circuit  126  is equal to or greater than the pressure in the first circuit  122 , as shown in  FIGS. 2-4 . Alternatively, or additionally, the controller  200  can open or partially open the second valve  162  after the pressure in the supplemental circuit  126  is equal to or greater than the pressure in the second circuit  124 . 
     When the first valve  160  is a check valve, fluid flows from the supplemental circuit  126  to the first circuit  122  when the pressure in the supplemental circuit  126  is equal to or greater than the combined pressure in the first circuit  122  and the selected cracking pressure of the first check valve  160 , as shown in  FIGS. 5-8 . Alternatively, or additionally, when the second valve  162  is a check valve, fluid flows from the supplemental circuit  126  to the second circuit  124  when the pressure in the supplemental circuit  126  is equal to or greater than the combined pressure in the second circuit  124  and the selected cracking pressure of the second check valve  162 . 
     The supplemental pump  150  continues to provide additional flow in the use condition until the additional flow is no longer required, for example when the flow demand or load of the first circuit  122  decreases below the flow threshold of the first pump  130 . The flow threshold can be a predetermined percentage of the maximum available flow of the first pump  130  or the second pump  140 . The flow threshold can correspond to the displacement threshold of the first swashplate  132  of the first pump  130  or the second swashplate  142  of the second pump  140 . The controller  200  can determine additional flow is not required when the angle of the first swashplate  132  is at or below a displacement threshold. Alternatively, or additionally, the controller  200  can determine additional flow is not required when the pressure in the first circuit  122  is at or below a pressure threshold. The supplemental pump  150  returns to the standby condition when the supplemental load sense circuit  154  provides a reduced or minimal load sense pressure to the load sensing compensator  156 . The controller  200  can decrease or reduce the pressure in the supplemental load sensing circuit  154  to provide a reduced or minimal load sense pressure to the load sensing compensator  156  returning the supplemental pump  150  to the standby condition. 
     According to some implementations, the controller  200  can control the supplemental valve  170  to reduce the pressure provided to the load sensing compensator  156  via the supplemental load sense circuit  154  returning the supplemental pump  150  to the standby condition. In  FIGS. 2 and 3 , the controller  200  controls the pressure reducing or pressure reducing and relieving valve  170  to reduce the pressure in the supplemental load sense circuit  154  and the load sensing compensator  156 . In  FIGS. 4-7 , the controller  200  moves or maintains the directional control valve or proportional direction control valve  170  in the first position reducing the pressure in the supplemental load sense circuit  154  provided to the load sensing compensator  156 . 
     In other implementations, the pressure differential between the first circuit  122  and the first load sense circuit  134  moves or maintains the first supplemental valve  170  in the first position, as shown in  FIG. 8 . Alternatively, or additionally, the pressure differential between the second circuit  124  and the second load sense circuit  144  moves or maintains the second supplemental valve  180  in the first position. When the flow demand or load of the first circuit  122  decreases below the flow threshold of the first pump  130 , the pressure in the first load sense circuit  134  decreases, which decreases the pressure in the second pilot line  176 . When the pressure in the second pilot line  176  is less than the combined pressure in the first pilot line  172  and the first spring  171  force, then the first supplemental valve  170  returns to the first position. When the flow demand or load of the second circuit  124  decreases below the flow threshold of the second pump  140 , the pressure in the second load sense circuit  144  decreases, which decreases the pressure in the fourth pilot line  186 . When the pressure in the fourth pilot line  186  is less than the combined pressure in the third pilot line  182  and the second spring  181  force, then the second supplemental valve  180  returns to the first position. 
       FIG. 9  illustrates a method providing additional flow in a hydraulic system  120 , which may be utilized in one or more of the implementations described herein and depicted in the various FIGURES. The following description is also applicable to the second circuit  124  or to both the first and second circuits  122 ,  124 . At step  300 , the method starts. 
     At step  302 , the hydraulic system  120  determines whether an implement hydraulic system  114  is connected. The controller  200  can determine whether the first circuit  122  is connected to the first implement circuit  116  based in part on the first swashplate angle sensor  202 , the first pressure sensor  208 , or both. If the hydraulic system  114  of the implement  112  is connected to the hydraulic system  120  of the work vehicle  100 , then the method continues to step  304 . Otherwise, the method returns to step  302 . 
     At step  304 , the hydraulic system  120  determines the flow demand and load of the first circuit  122 . The controller  200  communicates with the swashplate angle sensor  202  to determine flow demand and the pressure sensor  208  to determine the load. Alternatively, the hydraulic circuit  120  determines the flow demand and load based at least in part on the pressure differential between the first circuit  122  and the first load sense circuit  134 . 
     At step  306 , the hydraulic system  120  determines whether the flow demand of the implement hydraulic system  114  exceeds a flow threshold of the work vehicle hydraulic system  120 . The controller  200  can determine the flow demand is above the flow threshold when the angle of the first swashplate  132  is at or above a displacement threshold. Alternatively, the hydraulic circuit  120  can determine the flow demand is above a flow threshold based at least in part when the pressure differential between the first circuit  122  and the first load sense circuit  134  causes the first supplemental valve  170  to move to the second position. If the flow demand is above the flow threshold, then the method continues to step  308 . Otherwise, the method returns to step  304 . 
     At step  308 , the hydraulic system  120  provides an increased load sense signal or pressure to the supplemental pump  150 . The controller  200  can control the position of the first supplemental valve  170  to provide the appropriate pressure to the load sensing compensator  156  of the supplemental pump  150 . The controller  200  can control the position of the first supplemental valve  170  to provide pressure from the supplemental circuit  126 , the first load sense circuit  134 , or the first circuit  122  to the load sensing compensator  156 . Alternatively, the hydraulic system  120  can provide pressure from the first load sense circuit  134  to the load sensing compensator  156  based at least in part on the pressure differential between the first circuit  122  and the first load sense circuit  134 . 
     At step  310 , the supplemental pump  150  increases the flow in the supplemental circuit  126  based on the pressure differential between the supplemental load sense circuit  154  and the supplement circuit  126 . When the pressure in the supplement circuit  126  is at or above the pressure in the first circuit  122 , the controller  200  opens the first valve  160  to allow the additional flow from the supplemental circuit  126  to the first circuit  122 . Alternatively, the first check valve  160  opens when the pressure in the supplemental circuit  126  is equal to or greater than the combined pressure in the first circuit  122  and the selected cracking pressure of the first check valve  160 . 
     At step  312 , the method of providing additional flow in a hydraulic system  120  is complete, according to one implementation. In other implementations, one or more of these steps, processes, or operations may be omitted, repeated, re-ordered, combined, or separated and still achieve the desired results. 
       FIG. 10  illustrates a method providing additional flow in a hydraulic system  120 , which may be utilized in one or more of the implementations described herein and depicted in the various FIGURES. At step  400 , the method starts. 
     At step  402 , the work vehicle hydraulic system  120  is connected to the implement hydraulic system  114 . The first circuit  122  is connected to the first implement circuit  116  via a first set of SCVs  138 , and the second circuit  124  is connected to the second implement circuit  118  via second set of SCVs  148 . 
     At step  404 , the controller  200  communicates with the first swashplate angle sensor  202 , the second swashplate angle sensor  204 , the first pressure sensor  208 , and the second pressure sensor  210 . The controller  200  determines flow demand of the first implement circuit  116  based in part on the first swashplate angle sensor  202  and the flow demand the second implement circuit  118  based in part on the second swashplate angle sensor  204 . The controller  200  determines the load of the first implement circuit  116  based in part on the first pressure sensor  208  and the load of the second implement circuit  118  based in part on the second pressure sensor  210 . 
     At step  406 , the hydraulic system  120  determines whether the flow demand of the first implement circuit  116  exceeds the flow threshold of the first pump  130 . The controller  200  can determine the flow demand is above the flow threshold when the angle of the first swashplate  132  is at or above a displacement threshold. Alternatively, the hydraulic circuit  120  can determine the flow demand is above a flow threshold based at least in part when the pressure differential between the first circuit  122  and the first load sense circuit  134  causes the first supplemental valve  170  to move to the second position. If the flow demand of the first implement circuit  116  is above the flow threshold, then the hydraulic system  120  provides a load sense signal or pressure to the supplemental pump  150 . The controller  200  can control the position of the first supplemental valve  170  to provide pressure to the load sensing compensator  156  from the supplemental circuit  126 , the first load sense circuit  134 , or the first circuit  122 . Alternatively, the hydraulic system  120  can provide pressure from the first load sense circuit  134  to the load sensing compensator  156  based in part on the pressure differential between the first circuit  122  and the first load sense circuit  134 . When the pressure in the second pilot line  176  is equal to or greater than the combined pressure in the first pilot line  172  and the first spring  171  force, the first supplemental valve  170  moves to the second position and the load sensing compensator  156  receives the pressure from the first load sense circuit  134  causing the supplemental pump  150  to increase the flow in the supplemental circuit  126 . 
     At step  408 , when the pressure in the supplement circuit  126  is at or above the pressure in the first circuit  122 , the controller  200  opens the first valve  160  to allow the additional flow from the supplemental circuit  126  to the first circuit  122 . Alternatively, the first check valve  160  opens when the pressure in the supplemental circuit  126  is equal to or greater than the combined pressure in the first circuit  122  and the selected cracking pressure of the first check valve  160 . 
     At step  410 , the supplemental pump  150  provides additional flow to the first circuit  122 . 
     At step  412 , the hydraulic system  120  determines whether the flow demand of the second implement circuit  118  exceeds the flow threshold of the second pump  140 . The controller  200  can determine the flow demand is above the flow threshold when the angle of the second swashplate  142  is at or above a displacement threshold. Alternatively, the hydraulic circuit  120  can determine the flow demand is above a flow threshold based at least in part when the pressure differential between the second circuit  124  and the second load sense circuit  144  causes the second supplemental valve  180  to move to the second position. If the flow demand in the second implement circuit  118  is above the flow threshold, then the hydraulic system  120  provides a load sense signal or pressure to the supplemental pump  150 . The controller  200  can control the position of the second supplemental valve  180  to provide pressure to the load sensing compensator  156  from the supplemental circuit  126 , the second load sense circuit  144 , or the second circuit  124 . Alternatively, the hydraulic system  120  can provide pressure from the second load sense circuit  144  to the load sensing compensator  156  based in part on the pressure differential between the second circuit  124  and the second load sense circuit  144 . When the pressure in the fourth pilot line  186  is equal to or greater than the combined pressure in the third pilot line  182  and the second spring  181  force, the second supplemental valve  180  moves to the second position and the load sensing compensator  156  receives the pressure from the second load sense circuit  144  causing the supplemental pump  150  increases the flow in the supplemental circuit  126 . 
     At step  414 , when the pressure in the supplement circuit  126  is at or above the pressure in the second circuit  124 , the controller  200  opens the second valve  162  to allow the additional flow from the supplemental circuit  126  to the second circuit  124 . Alternatively, the second check valve  162  opens when the pressure in the supplemental circuit  126  is equal to or greater than the combined pressure in the second circuit  124  and the selected cracking pressure of the second check valve  162 . 
     At step  416 , the supplemental pump  150  provides additional flow to the second circuit  124 . 
     At step  418 , the method of providing additional flow in a hydraulic system  120  is complete, according to one implementation. In other implementations, one or more of these steps, processes, or operations may be omitted, repeated, re-ordered, combined, or separated and still achieve the desired results. 
     Without in any way limiting the scope, interpretation, or application of the claims appearing below, a technical effect of one or more of the example implementations disclosed herein is a hydraulic system for a work vehicle which has a supplemental pump to provide additional flow to one or more primary hydraulic circuits connected to one or more implement hydraulic circuits. Another technical effect of one or more of the example implementations disclosed herein is a supplemental pump which provides additional flow on demand and has an efficient low pressure standby condition resulting in reduced parasitic losses. Another technical effect of one or more of the example implementations disclosed herein is allowing the work vehicle, such as an agricultural tractor, to operate at a lower engine speed and still maintain sufficient hydraulic flow for optimal implement performance. Operating at lower engine speeds improves the overall efficiency of the work machine. Lower engine speeds also reduce the noise level experienced by the operator and the surrounding environment. 
     The terminology used herein is for describing particular implementations and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that any use of the terms “has,” “includes,” “comprises,” or the like, in this specification, identifies the presence of stated features, integers, steps, operations, elements, and/or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. One or more of the steps or operations in any of the methods, processes, or systems discussed herein may be omitted, repeated, re-ordered, combined, or separated and are within the scope of the present disclosure. 
     As used herein, “e.g.” is utilized to non-exhaustively list examples and carries the same meaning as alternative illustrative phrases such as “including,” “including, but not limited to,” and “including without limitation.” Unless otherwise limited or modified, lists with elements that are separated by conjunctive terms (e.g., “and”) and that are also preceded by the phrase “one or more of” or “at least one of” indicate configurations or arrangements that potentially include individual elements of the list, or any combination thereof. For example, “at least one of A, B, and C” or “one or more of A, B, and C” indicates the possibilities of only A, only B, only C, or any combination of two or more of A, B, and C (e.g., A and B; B and C; A and C; or A, B, and C). 
     Any reference numbers, numerals, letters, or symbols in the claims are merely for reference and do not limit the scope of the claims to the one or more implementations represented herein. 
     While the above describes example implementations of the present disclosure, these descriptions should not be viewed in a restrictive or limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the appended claims.