ELECTRONIC PRESSURE CONTROL OF DUAL PUMP SYSTEM

BACKGROUND

Hydraulic systems are favored in a number of applications due to the ability of hydraulics to move heavier loads and provide greater force than mechanical, electrical, or pneumatic systems. The use of a liquid allows the system to provide a constant force and torque, independent of speed, and to cope with large weight ranges with few moving parts. Fewer moving parts contributes to the increased durability of hydraulic systems. Hydraulic systems are often simple to control, capable of great accuracy, and can reduce losses as the liquid does not absorb supplied energy.

These advantages can be attributed to the use of a pressured header of incompressible fluid to drive loads. To maintain continuous sufficient pressure in the header, a pump can supply pressure and additional liquid from a reservoir as necessary. However, during load application or shifting, significant amounts of liquid need to be moved rapidly and can saturate the capacity of a single pump. Hydraulic systems may therefore incorporate a second pump to supplement the main pump during system excursions. When both the main pump and the supplementary pump are operating to supply a common flow path, competition between the pumps can lead to instability in the system.

SUMMARY

In some aspects presented herein, the present disclosure relates to a system for electronic pressure control of pumps in a dual pump system. The system may include a controller; a primary pump operated by the controller to maintain a system pressure in a flow path at a first pressure setpoint; a pressure transducer reading the system pressure and providing the system pressure to the controller; and a secondary pump operated by the controller to maintain the system pressure at a second pressure setpoint, the second pressure setpoint being less that the first pressure setpoint. In other aspects, the controller operates the secondary pump in a standby mode.

In some implementations, the system further includes a primary motor driving the primary pump. In further examples, the controller operates the primary pump to maintain the system pressure at the first pressure setpoint by varying a first speed of the primary motor. In still further examples, the system also includes a secondary motor driving the secondary pump. In yet further aspects, the controller operates the secondary pump to maintain the system pressure at a second pressure setpoint by varying a second speed of the secondary motor.

In other aspects, the controller comprises a proportional-integral-derivative (PID) controller including an outer loop monitoring the system pressure and an inner loop controlling at least one of a first speed of the primary pump and a second speed of the secondary pump. In some implementations, at least one of the primary pump and the secondary pump is an electronically pressure compensated pump. In further examples, each of the primary pump and the secondary pump is an electronically pressure compensated pump. In some examples, the controller is a first controller associated with the primary pump and the system further comprises a second controller associated with the secondary pump.

In some aspects presented herein, the present disclosure relates to a method of electronic pressure control of pumps in a dual pump system. The method includes maintaining, by a controller operating a first pump, a system pressure in a closed fluid system at or above a first setpoint pressure by: receiving, from a pressure transducer, the system pressure; comparing the system pressure with the first setpoint pressure; and adjusting, based on comparing the system pressure with the first setpoint pressure, a first speed of the first pump. The method may further include monitoring, by the controller operating a second pump, the system pressure, received from the pressure transducer, to maintain the system pressure above a second setpoint pressure, the second setpoint pressure being less than the first setpoint pressure, by: comparing the system pressure with the second setpoint pressure; determining, based on comparing the system pressure with the second setpoint pressure, that the system pressure is below the second setpoint pressure; and initiating the second pump, in response to determining the system pressure is below the second setpoint pressure.

In other aspects, the method further includes determining, based on comparing the system pressure with the secondary setpoint pressure, that the system pressure is above a third setpoint pressure; and placing the secondary pump in a standby mode, in response to determining that the system pressure is above a third setpoint pressure. In further examples, the third setpoint pressure and the secondary setpoint pressure are a same pressure. In some further examples, the secondary setpoint pressure is less than the third setpoint pressure. In yet further examples, the third setpoint pressure is less than the primary setpoint pressure. In still further examples, the method includes adjusting the secondary setpoint pressure.

In further examples, the method includes adjusting both the first setpoint pressure and the second set point pressure such that the first set point pressure is lower than the second setpoint pressure. In other aspects, the method includes detecting instability in the system pressure; and reducing the secondary setpoint pressure. In some implementations, the method also includes analyzing the system pressure over one or more runs of the secondary pump; determining the system pressure is stable over the one or more runs of the secondary pump; and increasing the secondary setpoint pressure.

In other aspects presented herein, the present disclosure relates to a computer system for electronic pressure control of pumps in a dual pump system. The computer system includes at least one processor and a memory in communication with the processor and containing instructions that when executed cause the processor to: maintain, by operating a primary pump, a system pressure in a closed fluid system at or above a primary setpoint pressure by: receiving, from a pressure transducer, the system pressure; comparing the system pressure with the primary setpoint pressure; and adjusting, based on comparing the system pressure with the primary setpoint pressure, a first output of a primary pump. The instructions may further cause the processor to monitor the system pressure, received from the pressure transducer, to maintain the system pressure above a secondary setpoint pressure, the secondary setpoint pressure being less than the primary setpoint pressure, by: comparing the system pressure with the secondary setpoint pressure; determining, based on comparing the system pressure with the secondary setpoint pressure, that the system pressure is below the secondary setpoint pressure; and initiating a secondary pump, in response to determining the system pressure is below the secondary setpoint pressure.

A variety of additional inventive aspects will be set forth in the description that follows. The inventive aspects can relate to individual features and to combinations of features. It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad inventive concepts upon which the embodiments disclosed herein are based.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the description, illustrate several aspects of the present disclosure. A brief description of the drawings is as follows:

FIG. 1 illustrates a schematic diagram of an example fluid distribution system, in which aspects of the present disclosure may be implemented.

FIG. 2 illustrates a schematic diagram of the fluid distribution system of FIG. 1 connected to an example flow path, in which aspects of the present disclosure may be implemented.

FIG. 3 illustrates a flowchart of an example method of controlling the pumps of a dual pump system, according to aspects of the present disclosure.

FIG. 4 illustrates a graph of pressure over time during a pressure excursion.

FIG. 5 illustrates a graph of pump displacement over time during a pressure excursion.

FIG. 6 illustrates an example computing system with which aspects of the present disclosure may be implemented.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary aspects of the present disclosure that are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

Aspects of the present disclosure are directed to a system for electronic pressure control of pumps in a dual pump system. In some embodiments, the system includes a primary pump with a controller operating the primary pump to maintain a system pressure in a flow path at a first pressure setpoint. The system further includes a pressure transducer reading the system pressure and providing the system pressure to the controller and, in some embodiments, directly to the primary pump and a secondary pump. The controller operates the secondary pump to maintain the system pressure at a second pressure setpoint, the second pressure setpoint being less than the first pressure setpoint.

Further aspects of the present disclosure are directed to a method of electronic pressure control of pumps in a dual pump system. In some embodiments, the method includes maintaining, by a controller operating a first pump, a system pressure in a closed fluid system at or above a first setpoint pressure by receiving, from a pressure transducer, the system pressure; comparing the system pressure with the first setpoint pressure; and adjusting, based on comparing the system pressure with the first setpoint pressure, a first output of the first pump. The method further includes monitoring, by the controller operating a second pump, the system pressure, received from the pressure transducer, to maintain the system pressure above a second setpoint pressure, the second setpoint pressure being less than the first setpoint pressure, by: comparing the system pressure with the second setpoint pressure; determining, based on comparing the system pressure with the second setpoint pressure, that the system pressure is below the second setpoint pressure; and initiating the second pump, in response to determining the system pressure is below the second setpoint pressure.

As used herein, “primary” refers to a pump in the dual pump system with a higher setpoint pressure, as compared with a setpoint for another pump in the dual pump system. As used herein, “secondary” refers to a pump in the dual pump system with a lower setpoint pressure, as compared with a setpoint for another pump in the dual pump system. While pumps in a dual pump system may be designated as primary or secondary in examples presented herein, those of skill in the art will recognize that such designations are not fixed. Either pump, or any pump in a system having more than two pumps, to which the principals of the present disclosure will also apply, may be designated primary or secondary. A pump may have its designation changed, such that a primary pump has its setpoint changed to be lower and becomes a secondary pump, or a secondary pump has its setpoint changed to be higher and becomes a primary pump.

In traditional dual pump systems, mechanical control in the form of check valves at the pump outlets have been used to prevent competition between the pumps during concurrent operation. Each pump is provided with a check valve at the outlet, with different cracking pressures for each pump which will, in effect, prioritize one pump over the other. A primary system pump has an outlet check valve with a minimal cracking pressure setting so that the primary pump continuously provides flow demand to the system at the primary pump's output pressure setting during normal operations. The primary pump may be configured with an output pressure setting at or near a desired system pressure. A secondary system pump has an outlet check valve with a cracking pressure greater (e.g., requiring a greater pressure differential to permit the valve to open) than that of the primary pump check valve, so that the secondary system pump only provides flow to the system when the system pressure decays below the differential pressure of the secondary valve setting. In this way, the secondary pump only operates to restore system pressure to the desired system pressure following a drop in pressure.

However, this arrangement has a number of drawbacks. First, significant separation between the cracking pressure of the two outlet check valves is necessary to prevent the secondary pump from interfering with the primary pump maintaining normal system pressure. This, in turn, leads to a second problem, as the wide difference between the two cracking pressures means a significant drop in system pressure is necessary before the secondary outlet check valve will open and the secondary pump can participate in supplying system pressure. This arrangement therefore leads to the system being subject to large pressure drops, which contributes to decreased performance. Finally, this arrangement requires the secondary pump to remain running throughout system operations, regardless of whether the secondary pump is contributing to system pressure, which leads to increased wear on components.

Disclosed herein are systems and method which provide solutions to these problems and provide additional advantages over the arrangement described above. Aspects of the present disclosure relate to a dual pump system using pumps with electronic pressure compensation. In some aspects, the pumps are motor pumps, with pressure compensation provided through varying of the motor speed. Use of electronic pressure compensation provides improved response time by both the primary and secondary pumps in response to pressure drop in the header. Because the setpoints can be set and adjusted electronically, either pump in a dual pump system may be designated a “primary” or a “secondary” pump. As the operational demands of a primary pump are significantly higher than a secondary pump, the ability to change the primary designation between the pumps in the system provides more even wear between the pumps and can extend the life of system components and the system overall.

In a dual hydraulic pump system that is controlled using electronic pressure compensation, one or more pressure transducers may be used for feedback to the control loop. However, failure to appropriately configure the pressure compensation setpoints can lead to problems within the system, such as pump instability. In a hydraulic system powered by two pressure compensated pumps with equal compensator setpoints, instability or “crosstalk” can occur between the pumps as they compete to deliver the required flow.

In more modern, electronically controlled systems, an improved methodology is needed to manage the hydraulic instability between multiple pumps. As is disclosed herein, a separation of pressure setpoints between the pumps in the dual pump system may eliminate and prevent pump instability in a system using electronic pressure compensation, when the separation is properly configured. For example, a first pump is controlled based on a first pressure setpoint and a second pump is controlled based on a second pressure setpoint, wherein the first pressure setpoint and the second pressure setpoint are different setpoints, e.g., the first pressure setpoint is 3000 psi and the second pressure setpoint is 2900 psi. In some embodiments, one pump in the dual pump system is configured as a primary pump and another pump in the dual pump system is a secondary pump. A pump may have its designation changed without a change in its own setpoint. For example, if a first pump is configured as a primary pump with a higher setpoint than a second pump configured as a secondary pump, and the second pump has its setpoint raised to be higher than the setpoint of the first pump, the first pump becomes the secondary pump without a change in its own setpoint.

According to aspects of the present disclosure, the instability associated with crosstalk between the pumps is remedied electronically by establishing a primary and secondary pump within the system, with each having a different pressure setpoint defined in their respective controller. The pressure feedback taken, for example, from a pressure transducer at a hydraulic outlet of the pumps, is used and compared to the respective setpoints to drive the operation of each pump. When the primary pump, with the higher setpoint, saturates from a system flow demand in excess of the primary pump's capacity, the system pressure will drop, signaling the secondary pump to provide flow. The separation of control setpoint pressures in the controller prevents crosstalk of the two pump and the associated instability. Pressure setpoints can be established manually or learned by respective pump controllers during operation. Pressure setpoints can also be dynamically adjusted under certain system operating conditions to converge on the desired output pressure.

Aspects of the present disclosure relate to an arrangement of two pumps powered by independent controllers, connected to a common output port into a hydraulic system. A first pump, with a first controller, is designated as the primary hydraulic power source. A second pump, with a second controller, is designated the secondary hydraulic power source. In some embodiments, the first controller and the second controller both contain the same closed-loop control system for the associated pump to maintain a defined pressure. The first controller maintains a first defined pressure with the first pump. The second controller maintains a second defined pressure with the second pump, where the second defined pressure is lower than the first defined pressure. In some implementations, a single controller provides the functionality of both the first and second controller.

As long as the capacity of the first pump is not exceeded, only the first pump will run. When the first pump becomes saturated due to high system demand and cannot maintain the first defined pressure, the system pressure will drop below the second defined pressure. When system pressure drops below the second defined pressure, the second pump will start to provide additional flow to the system. Electronic pressure control permits optimization of the secondary setpoint by reducing the amount of separation needed between the setpoints of the primary pump and the secondary pump.

In addition to providing greater accuracy, this also contributes to the ability to supply greater overall system pressure and more consistent pressure in the supplied system. Because the secondary setpoint can be optimized, less of a downward flux in system pressure is necessary to trigger the secondary pump to come online and contribute to maintaining system pressure in a desired range. Whereas a mechanically based system requires a significant difference between the cracking pressures of the two check valves due to the limited sensitivity and relatively slow response of the check valves, systems embodying the present disclosure can respond quickly and before a large drop in pressure occurs. This results in more consistent overall pressure to the supplied loads.

Further, in some embodiments, the controller can include programming for artificial intelligence or machine learning to enable the controller to continually optimize the setpoints of both pumps. In this way, the controller may bring the two setpoints into an optimized proximity, providing greater accuracy and, further, enabling automated adjustment of the setpoints to changing system conditions.

FIG. 1 illustrates a schematic diagram of an example fluid distribution system 100 in which embodiments of the present disclosure may be implemented. Fluid distribution system 100 is operable for selectively providing fluid, such as hydraulic, cooling, or lubricating fluid, at a given pressure to one or more components or loads. Fluid distribution system 100 may have various configurations depending on the application. Fluid distribution system 100, in some embodiments, is a hydraulic system and, in more particular examples, is a hydraulic system to support various flight control systems.

The example illustrated in FIG. 1 operates to distribute pressurized fluid for use in hydraulic flight systems. Examples presented herein are directed to hydraulic and flight system examples, but those of skill in the art will understand that the principals disclosed are applicable in diverse applications. Example hydraulic loads for fluid distribution system 100 include flight control systems, such as a slats power control unit (PCU), flaps PCU, landing gear including associated components (e.g., landing gears doors), elevators, and rudders.

Primary pump 102 operates to pressurize and maintain flow throughout a flow path supplied by fluid distribution system 100. An example flow path 150, to be supplied by fluid distribution system 100, is shown in FIG. 2. The supplied flow path is connected to fluid distribution system 100 through outlet port 120. Primary pump 102 may generally operate continuously to maintain sufficient delivery pressure throughout fluid distribution system 100.

Secondary pump 104 operates to restore distribution pressure throughout fluid distribution system 100 when system pressure drops below a predetermined secondary setpoint. Secondary pump 104 also operates to provide additional flow to maintain flow to system loads when primary pump 102 becomes saturated due to high demand. Secondary pump 104 may generally operate in a standby mode or a shutoff mode.

Primary motor 106 operates to drive primary pump 102. In some embodiments, primary motor 106 is a variable speed motor and the speed of primary motor 106 determines the output pressure and/or displacement of primary pump 102. Secondary motor 108 operates to drive secondary pump 104. In some embodiments, secondary motor 108 is a variable speed motor and the speed of secondary motor 108 determines the output pressure and/or displacement of secondary pump 104.

In embodiments, each of primary pump 102 and secondary pump 104 are pressure compensated pumps. Each of primary pump 102 and secondary pump 104 is configured to maintain a predetermined outlet pressure when operating. In some examples, one or more of the pumps is a fixed displacement pump. Outlet pressure may be maintained by adjusting pump speed, such as by adjusting the speed of primary motor 106 or secondary motor 108. In some embodiments, primary pump 102 and secondary pump 104 are two units of the same pump, with matching characteristics and capacities. In such embodiments, primary pump 102 and secondary pump 104 may differ only in their designated setpoint.

In some examples, one or more pumps in the system, such as primary pump 102 and secondary pump 104, is a variable displacement pump. A variable displacement pump may be operated as a pressure compensated pump, for example, by integrating a mechanical compensator, such as a servo or primary and secondary check valves with differing cracking pressures. Integration of principals of the present disclosure, including controller adjustment of pump speed responsive to system pressure, may reduce instances of instability or flow oscillations with the use of mechanical compensation.

Designation of primary pump 102 and secondary pump 104 is not fixed and may be changed or exchanged. Primary and secondary designation is determined according to setpoint pressure, which may be adjusted. In some embodiments, designation of primary and secondary may be exchanged on a predetermined schedule or when predetermined criteria are met. For example, primary and secondary designation may be exchanged each flight cycle or each time the system is started up. Designations may be exchanged periodically, such as weekly, monthly, quarterly, etc. Designations may be exchanged based on the condition of each pump, for example, a pump with greater wear is designated as the secondary pump and a pump with less wear is designated as the primary pump. As the primary pump runs significantly more than the secondary pump under normal conditions, exchanging designations, and thus sharing the significantly higher run time of the primary pump between two or more pumps, provides more even wear of system components and may extend the life of components, reducing overall maintenance needed by the system.

In some implementations, one or both of primary pump 102 and secondary pump 104 is a bidirectional pump. One or both of primary pump 102 and secondary pump 104 may be a unidirectional pump. In some embodiments, one of primary pump 102 and secondary pump 104 is a bidirectional pump and one is a unidirectional pump.

Primary controller 110 operates to provide control operations to primary pump 102 and primary motor 106. Secondary controller 112 operates to provide control operations to secondary pump 104 and secondary motor 108. Primary controller 110 and secondary controller 112 may be a single controller, or may be separate controllers with a common architecture and operations, or may be separate controllers with differing architecture or operations. In some embodiments, primary controller 110 and secondary controller 112 are different controllers. For example, primary controller 110 may be a smart controller containing logic for adjusting setpoints and secondary controller 112 may be a basic controller responsive to communications from primary controller 110.

In some embodiments, one or both of primary controller 110 and secondary controller 112 operate the associated pump as a pressure compensated pump. For example, once the output pressure of the pump reaches the setpoint pressure, the output pressure is regulated by the controller to maintain the setpoint pressure by changing the pump's speed. In some implementations, one or both of primary controller 110 or secondary controller 112 will regulate the pump's pressure through the entire speed range.

One or both of primary controller 110 and secondary controller 112 may receive pressure readings from pressure transducer 114, or otherwise be in communication with pressure transducer 114. Based on system pressure measurements received from pressure transducer 114 and, in some embodiment, other data relating to system conditions and pump operations, one or both of primary controller 110 and secondary controller 112 may perform system analytics.

System analytics may include determining an adjustment to one or more of primary setpoint pressure and secondary setpoint pressure. In embodiments where primary and secondary designations are exchanged between the two pumps, the most recent primary and secondary setpoint pressures used in the system may be preserved, such that each pump assumes the same setpoint pressure most recently used by the pump with which it is exchanging designation. In some implementations, each pump may record and maintain its own setpoint pressures for both a primary and a secondary designation.

Primary and secondary setpoints may be optimized for each pair of pump models, or each individual pair of pumps. In some embodiments, setpoints are optimized for various thermal or other conditions of fluid distribution system 100, and setpoints are adjusted by the controller in response to detected system conditions.

In some embodiments, primary setpoint pressure is relatively fixed, in comparison to secondary setpoint pressure, by overall pressure parameters or requirement for fluid distribution system 100 and flow path 150. Secondary setpoint pressure may be adjusted for optimization or improvement in consideration of one or more factors. Factors which may be considered include, by way of nonlimiting examples, separation between the primary setpoint pressure and the secondary setpoint pressure, time elapsed between an initial drop in system pressure and response by the secondary pump, time elapsed between saturation of the primary pump and response by the secondary pump, stability of the system during operation of the secondary pump, and frequency of pressure excursions. In some embodiments, primary setpoint pressure is fully variable and supplies a variable pressure system.

For example, the secondary setpoint pressure may be adjusted to be closer to the primary setpoint pressure to improve the response time of the secondary pump when low pressure excursion occur in fluid distribution system 100. The secondary setpoint pressure may be adjusted to be lower and therefore farther from the primary setpoint pressure if instability is determined to be present in the system during operation of the secondary pump. Reducing the secondary setpoint pressure reduces the occurrence of crosstalk between the primary pump and the secondary pump and increases system stability.

In some embodiments, each of primary controller 110 and secondary controller 112 perform analytics and independently apply the analytics to optimize the setpoint pressure of the associated pump. Primary controller 110 and secondary controller 112 may independently perform analytics and communicate analytic outcomes to each other to form a set of shared analytics. Setpoints for each of primary pump 102 and secondary pump 104 may be determined based on the shared analytics.

In some implementations, the controller includes artificial intelligence or machine learning algorithms or models. The controller may be configured to adjust the secondary setpoint pressure to be as close to the primary setpoint pressure as possible, while remaining lower than the primary setpoint pressure and maintaining system stability during initialization and operation of the secondary pump. Adjustment of one or both of the secondary setpoint pressure and the primary setpoint pressure may be automated, where the controller automatically adjusts setpoint pressure after making a determination.

In some embodiments, one or both of primary controller 110 and secondary controller 112 includes a proportional-integral-derivative (PID) controller. Measurement of system pressure received from pressure transducer 114 provides feedback to the PID controller. In some implementations, the PID controller uses both an outer pressure loop, based on system pressure, and an inner speed loop, based on the motor speed of the associated pump.

Pressure transducer 114 operates to provide a measurement or other indication of system pressure within fluid distribution system 100. Pressure transducer 114 may generally be arranged to measure pressure at the hydraulic output of both primary pump 102 and secondary pump 104. In some embodiments, fluid distribution system 100 includes more than one pressure transducers 114. For example, a first pressure transducer is arranged to measure pressure at the output of primary pump 102 and second pressure transducer is arranged to measure pressure at the output of secondary pump 104. In some implementations, it may be preferred to use one pressure transducer 114 to monitor system pressure and to inform both primary controller 110 and secondary controller 112. Use of a common pressure transducer 114 to inform both primary controller 110 and secondary controller 112 may provide increased system stability.

Wiring harness 116 provides communication between components of fluid distribution system 100. In some embodiments, wiring harness 116 provides communication between primary controller 110 and secondary controller 112. Wiring harness 116 may provide communication between pressure transducer 114 and one or more of primary controller 110 and secondary controller 112. In embodiments including more than one pressure transducers 114, wiring harness 116 may provide additional communication between the more than one pressure transducers 114 and one or more of primary controller 110 and secondary controller 112. In some implementations, wiring harness 116 may be absent. Primary controller 110, secondary controller 112, and pressure transducer 114 may communicate wirelessly or be integrated with one another. In some embodiments, primary controller 110 and secondary controller 112 operate independently and do not communicate with one another. A single controller may perform the functions of both primary controller 110 and secondary controller 112.

Reservoir 118 provides a source of make-up liquid and a surge volume for fluid distribution system 100. An overall volume of fluid distribution system 100 and an associated flow path may vary with operations of loads on the flow path. Reservoir 118 supplies a source of fluid to maintain a current volume of the header and flow path sufficiently occupied by fluid to sustain system pressure within parameters.

Outlet port 120 provides an outlet from fluid distribution system 100 to a flow path or other loads to be supplied. Return port 122 provides a return for liquid from loads supplied by fluid distribution system 100 and closes the loop of the distribution. Fluid distribution system 100 may generally be a closed loop system where pressurized fluid is distributed to loads arranged along a flow path via outlet port 120 and returned to fluid distribution system 100 via return port 122 to be repressurized. In embodiments, fluid distribution system 100 may include multiple flow paths for selectively distributing the pressurized fluid to various hydraulically actuated components associated with the respective flow paths.

FIG. 2 illustrates a schematic diagram of the example fluid distribution system 100 of FIG. 1 connected to an example flow path 150 in which embodiments of the present disclosure may be implemented. For purposes of illustration, flow path 150 is shown to include a single flow path, although in practice additional flow paths may be provided depending on the requirements of a particular application. By way of example, two flow paths may be provided to include a high-pressure path and a low-pressure path each supplying loads with differing pressure and flow requirements. Flow path 150 depicts several example loads, in the context of hydraulic flight control systems, and is nonlimiting as other possible loads and applications will be apparent to those of skill in the art. Example loads presented in FIG. 2 include a slats PCU 152, landing gear 154, landing gear doors, 156, a flaps PCU 158, elevators 160 and 164, and rudders 162.

FIG. 3 illustrates a flowchart of an example method 200 of controlling the pumps of a dual pump system. Method 200 is presented in the context of a hydraulic system, such as fluid distribution system 100, but the principals of method 200 will be readily applied to other dual pump systems, or larger multi-pump systems, by those of skill in the art. While example method 200 is presented in the context of a dual pump system, those of skill in the art will understand the applicability of principals presented herein to other systems with different numbers of pumps. In some embodiments, method 200 may be performed by a single controller operating both a primary pump and a secondary pump.

Generally, a primary pump, such as primary pump 102 of FIG. 1, maintains pressure in a fluid distribution header at a primary setpoint pressure, illustrated at 202. System pressure is monitored and a determination is made whether system pressure is being maintained at the primary setpoint pressure. If a determination is made that system pressure is not below the primary setpoint pressure, illustrated at 204, the primary pump continues to maintain system pressure, illustrated at 202. System pressure is monitored by a pressure detector, such as pressure transducer 114 of FIG. 1.

Under some conditions, such as increased flow demand due to one or more operations using the hydraulic system, a determination that the pressure in the fluid distribution header is below a primary setpoint will be made, illustrated at 204, and the speed of the primary pump may be adjusted to raise system pressure back to the primary setpoint pressure, illustrated at 206. The determination and adjustment may be performed by a primary controller, such as primary controller 110 of FIG. 1, operating primary pump 102 which is driven by primary motor 106.

System pressure is monitored and a determination is made whether system pressure is falling below a secondary setpoint pressure. If a determination is made that system pressure is not below the secondary setpoint pressure, illustrated at 208, the primary pump continues to maintain system pressure, illustrated at 202. If a determination is made that system pressure is below the secondary setpoint pressure, illustrated at 208, the secondary pump is initiated to supplement the primary pump, illustrated at 210. The determination and initiation may be performed by a secondary controller, such as secondary controller 112 of FIG. 1, operating a secondary pump 104 driven by a secondary motor 108. Supplementing the primary pump, the secondary pump operates to maintain system pressure above the secondary setpoint pressure, illustrated at 212.

System pressure is monitored and a determination is made whether system pressure is rising above the setpoint, illustrated at 214. The setpoint at 214 may refer to the secondary setpoint pressure, where, in some embodiments, the secondary pump is stopped when system pressure rises above the secondary setpoint pressure. The setpoint at 214 may refer to the primary setpoint pressure, where, in some embodiments, the secondary pump is stopped when system pressure rises above the primary setpoint pressure. The setpoint at 214 may refer to a third setpoint pressure, where, in some embodiments, the secondary pump is stopped when system pressure rises above the third setpoint pressure. The third setpoint pressure may be different from one or both of the secondary setpoint pressure and the primary setpoint pressure. In some embodiments, the third setpoint pressure may be greater than the secondary setpoint pressure and less than the primary setpoint pressure.

If a determination is made that the setpoint has not been exceeded, illustrated at 214, the secondary pump continues to maintain system pressure at or above the secondary setpoint pressure, illustrated at 212. If a determination is made that the setpoint has been exceeded, illustrated at 214, the secondary pump speed is adjusted, illustrated at 216. The secondary pump may be stopped, as system pressure rising above the setpoint indicates that the primary pump is no longer saturated by system demand. In some embodiments, the secondary pump is slowed.

Maintenance of and excursions by the system pressure may be analyzed, illustrated at 218. Analysis of pump performance and system operation by a controller may look at pressure over time.

FIG. 4 illustrates a graph 300 of an example analysis of system pressure response based on the secondary setpoint pressure during a pressure excursion. Multiple example values for secondary setpoint pressure are reviewed in graph 300 and compared to determine which of the analyzed values for secondary setpoint pressure yields the best performance. As illustrated at 302, instability in the pumps appears as pressure fluctuating widely over a period of time. Instability can also be identified by the controller due to pressure rising above and dropping below an expected output pressure, based on the pump's motor speed, before leveling out. As illustrated at 304, stability in the pumps appears as a relatively constant pressure, where pressure comes up to expected output pressure, based on the pump's motor speed, without rapid or repeated fluctuations in output pressure.

Referring specifically to the example of FIG. 4, primary setpoint pressure is set at 3000 psi, based on system parameters. The secondary setpoint pressure is purposefully set lower than the primary setpoint pressure such that the secondary pump only operates with the primary pump cannot maintain system pressure along. During, for example, a low flow demand operation, the secondary pump remains in a standby mode or otherwise off. Setting the secondary setpoint pressure too close to the primary setpoint pressure may cause instability, such as the pumps competing to control the system pressure.

Five secondary pressure setpoints are presented in graph 300 ranging from 2900 psi to 3000 psi. While 2900 psi and 2950 psi exhibit relatively stable operation of the secondary pump, 2975 psi, 2990 psi, and 3000 psi demonstrate marked instability, observable at 302. 2950 psi therefore appears to be a threshold for stable behavior in a baseline configuration and 2900 psi may provide a starting point for adjustments made manually or automatically by the controller. In some embodiments, the margin between the primary setpoint pressure and the secondary setpoint pressure is reduced over time through continually tuning of the secondary setpoint pressure. Conditions and configurations supporting zero margin between the primary setpoint pressure and the secondary setpoint pressure may be determined, for example, by active triggering of the secondary pump, integration of hysteresis, or adding logic to increase the secondary setpoint pressure gradually once the primary pump has reached saturation.

Analysis of system pressure and pump performance may look at pump flow over time. FIG. 5 illustrates a graph 400 of pump flow over time during a pressure excursion. Graph 400 demonstrates how a controller may analyze, for example, response time of one or both of the primary pump and the secondary pump during a pressure excursion.

Illustrated at 402, during normal or baseline operations, only the primary pump is required to meet flow demand, which, in some embodiments, may be limited to leakage flow. The secondary pump remains off or otherwise in a standby mode. Illustrated at 404, a pressure excursions occurs in the system and the primary pump and secondary pump accelerate together after sensing the pressure drop via the pressure transducer and the controllers. Analysis may look at, for example, the rate of change of speed for each pump, the rate of change of pressure in the fluid distribution system, time elapsed between the pressure drop and the pump response (e.g., initial change in the pump's speed for each pump), etc. Illustrated at 406, system pressure is returned to normal and only the primary pump is required to meet normal flow demand, such as leakage flow. The secondary pump remains off.

In some embodiments, the controller or other system analyzing the system data may perform comparisons without generating graphs. Normal operation and maintenance of system pressure at the primary pressure setpoint by the primary pump is resumed, illustrated at 202.

FIG. 6 illustrates an example block diagram of a virtual or physical computing system 500. One or more aspects of the computing system 500 can be used to implement the systems and methods for electronic control of a dual pumps described herein. In particular, the computing system 500 may be used to implement one or both of primary controller 110 or secondary controller 112.

In the embodiment shown, the computing system 500 includes one or more processors 502, a system memory 508, and a system bus 522 that couples the system memory 508 to the one or more processors 502. The system memory 508 includes RAM (Random Access Memory) 510 and ROM (Read-Only Memory) 512. A basic input/output system that contains the basic routines that help to transfer information between elements within the computing system 500, such as during startup, is stored in the ROM 512. The computing system 500 further includes a mass storage device 514. The mass storage device 514 is able to store software instructions and data. The one or more processors 502 can be one or more central processing units or other processors.

The mass storage device 514 is connected to the one or more processors 502 through a mass storage controller (not shown) connected to the system bus 522. The mass storage device 514 and its associated computer-readable data storage media provide nonvolatile, non-transitory storage for the computing system 500. Although the description of computer-readable data storage media contained herein refers to a mass storage device, such as a hard disk or solid state disk, it should be appreciated by those skilled in the art that computer-readable data storage media can be any available non-transitory, physical device or article of manufacture from which the central display station can read data and/or instructions.

Computer-readable data storage media include volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer-readable software instructions, data structures, program modules or other data. Example types of computer-readable data storage media include, but are not limited to, RAM, ROM, EPROM, EEPROM, flash memory or other solid state memory technology, CD-ROMs, DVD (Digital Versatile Discs), other optical storage media, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by the computing system 500.

According to various embodiments of the invention, the computing system 500 may operate in a networked environment using logical connections to remote network devices through the network 501. The network 501 may be a computer network, such as an enterprise intranet and/or the Internet. The network 501 can include a LAN, a Wide Area Network (WAN), the Internet, wireless transmission mediums, wired transmission mediums, other networks such as aircraft protocol networks (e.g., ARINC, CAN bus, etc.), and combinations thereof. The computing system 500 may connect to the network 501 through a network interface unit 504 connected to the system bus 522. It should be appreciated that the network interface unit 504 may also be utilized to connect to other types of networks and remote computing systems. The computing system 500 also includes an input/output controller 506 for receiving and processing input from a number of other devices, including a touch user interface display screen, or another type of input device. Similarly, the input/output controller 506 may provide output to a touch user interface display screen or other type of output device.

As mentioned briefly above, the mass storage device 514 and the RAM 510 of the computing system 500 can store software instructions and data. The software instructions include an operating system 518 suitable for controlling the operation of the computing system 500. The mass storage device 514 and/or the RAM 510 also store software instructions, that when executed by the one or more processors 502, cause one or more of the systems, devices, or components described herein to provide functionality described herein. For example, the mass storage device 514 and/or the RAM 510 can store software instructions that, when executed by the one or more processors 502, cause the computing system 500 to receive and execute managing network access control and build system processes.

Referring to the figures and examples presented herein generally, the disclosed environment provides a physical environment with which aspects of the systems and methods disclosed herein can be implemented. Other environments are also possible and contemplated based on the subject matter disclosed herein. For example, the systems and methods of the present disclosure may be implemented in the context of an embedded computing system, which may be a standalone system or a network embedded computing system. Implementations using embedded computing systems may be the embedded system integrated with one or both of primary controller 110 or secondary controller 112, for example.

Having described the preferred aspects and implementations of the present disclosure, modifications and equivalents of the disclosed concepts may readily occur to one skilled in the art. However, it is intended that such modifications and equivalents be included within the scope of the claims which are appended hereto.

ELECTRONIC PRESSURE CONTROL OF DUAL PUMP SYSTEM

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