Method and system for mitigating hydraulic system sensor degradation

Abstract

Methods and systems for operating a hydraulic system including an electric pump, an accumulator, and a hydraulic actuator are presented. In one example, if degradation occurs in the pressure sensor, the pressure in the accumulator is estimated as a function of the volume of the accumulator and / or the magnitude of the current supplied to the electric pump.

Description

Technical Field

[0001] The present disclosure generally relates to methods and systems for mitigating sensor degradation in a hydraulic system. These methods and systems may be used to continue operation of the hydraulic system after sensor degradation is determined. Background Art

[0002] A vehicle or machine may include a hydraulic system that operates actuators that enable the vehicle or machine to perform tasks. For example, an excavator may include multiple hydraulic actuators that are used to move the bucket, adjust the position of the boom, and adjust the position of the arm. The hydraulic system can charge an accumulator so that the system can maintain the desired level of operation in the event of high hydraulic demand. The accumulator can be charged to a higher pressure by a pump, and the operation of the pump can be adjusted based on the indication of the accumulator pressure provided by the pressure sensor. However, the vehicle or machine may operate in a challenging environment in which the performance of the pressure sensor may be degraded. For example, the wires that power the sensor may age. As a result, the pressure sensor may enter a degraded state, where the output of the pressure sensor may not accurately represent the pressure in the accumulator and hydraulic system. As a result, the vehicle or machine can be shut down immediately to reduce the possibility of unexpected operation of the vehicle or machine.

[0003] The inventors of the present invention have recognized the above problems and developed a method for operating a system including a sensor array, the method comprising: adjusting the operation of a pump based on the output of a pressure sensor indicating the pressure in the accumulator; and adjusting the operation of the pump based on the amount of current delivered to the pump and an indication of degradation of the pressure sensor.

[0004] When a pressure sensor fails, the operation of the electric pump can be adjusted according to the magnitude of the current delivered to the electric pump, so that it is possible to achieve the technical result of continuing to operate the vehicle or machine in an expected manner. In particular, the pressure in the accumulator of the vehicle or machine can be estimated based on the magnitude of the current of the electric pump. Therefore, the vehicle or machine can continue to operate the hydraulic system in a feedback control mode.

[0005] The present description has several advantages. In particular, the method allows the hydraulic system of a vehicle or machine to continue to operate, thereby enabling an orderly shutdown of the vehicle or machine. Furthermore, even if the pressure sensor is degraded, the method allows the system to continue to operate with no or less operational restrictions. Furthermore, the method can be implemented without excessive financial expenditure.

[0006] It should be understood that the above summary is intended to introduce in simplified form the concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is solely determined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1A A machine including a hydraulic system is shown;

[0008] Figure 1B Another machine (transmission) including a hydraulic system is shown;

[0009] Figure 2 is a schematic diagram of a control system of an example vehicle or machine;

[0010] Figure 3 A detailed view of an example of a machine's hydraulic system is shown;

[0011] Figure 4 An example showing the relationship between hydraulic pump torque and hydraulic system accumulator pressure;

[0012] Figure 5 Shows the Figure 6 An example of a method's hydraulic system operating sequence;

[0013] Figure 6 A flow chart of an example method of operating a vehicle or machine hydraulic system is shown;

[0014] Figure 7 is a graph of the volume of fluid stored in the hydraulic accumulator versus the pressure of fluid stored in the hydraulic accumulator; and

[0015] Figure 8 The relationship between electric pump current and pump torque is shown. DETAILED DESCRIPTION

[0016] The following description relates to systems and methods for operating a hydraulic system of a machine or vehicle. When the pressure sensor is not degraded, the system and method operate based on feedback from the pressure sensor. If the pressure sensor fails, the system may continue to operate based on a pressure estimate based on the volume of fluid stored in the accumulator or the current consumed by the electric pump. Figure 1A and 1B As shown, the method and system can be applied to a vehicle or machine. The system and method can be used Figure 2 The system and method may be operated as follows: Figure 3 The hydraulic system shown. The system and method can be based on Figure 4 The relationship shown is used to estimate the pressure in the hydraulic system. Figure 6 The method, system and method can be Figure 5 The order of operation is . Figure 7 and Figure 8 Shows that the Figure 6 The relationship between the method and the system application of Figures 1-3.

[0017] Figure 1A A view of an example machine including a hydraulic system is shown. However, it will be appreciated that the systems and methods described herein are not limited to Figure 1A The machine type shown. Instead, the systems and methods described herein may be applied to other machines, mechanisms, or vehicles, such as, but not limited to, cranes, backhoes, graders, crawlers, scrapers, etc. In addition, the methods and systems described herein may also be applied to Figure 1A Systems where sensors are installed in locations other than

[0018] Figure 1A An example of a machine 100 is shown that includes a plurality of hydraulic actuators that can be used to operate the machine 100. In this example, the machine 100 includes a cab 100 that is coupled to a propulsion device 110 (e.g., a drive track). The cab 100 can rotate about the drive track 110 via a swing gear 112. A boom 102 is coupled to the cab 100 and can be moved relative to the cab 100 via a hydraulic cylinder 114. A boom 106 is coupled to the boom 102 so that the boom 106 can rotate about the boom 102. The hydraulic cylinder 116 can be extended or retracted to rotate the arm 106 about the boom 102. A tool 108 (e.g., a bucket) is coupled to the arm 106 so that the tool 108 can rotate about the arm 106. The hydraulic cylinder 118 can be extended and retracted to rotate the tool 108 about the arm 106. The direction of power transmission is from the cab 100 to the tool 108, through various coupling components (e.g., boom, articulation, arm, and tool). Thus, cab 100 is located upstream of implement 108 in terms of the direction of power transmission of the system.

[0019] Now please refer to Figure 1B , Figure 1B is an example of a second machine 150 (eg, a transmission) that is an alternative machine that may be part of a system and based on Figure 4 method to operate. Figure 1BA detailed illustration of an example of a dual clutch transmission (DCT) is shown. In the figure, the engine crankshaft 40B is connected to the clutch housing 193. Alternatively, a shaft can connect the engine crankshaft 40B to the clutch housing 193. The clutch housing 193 can rotate with the rotation of the crankshaft 40B. The clutch housing 193 may include a first clutch 324 and a second clutch 322. In addition, the first clutch 324 and the second clutch 322 have associated first clutch plates 190 and second clutch plates 191, respectively. In some examples, the clutch may include a wet clutch or a dry clutch immersed in oil (for cooling). The engine torque can be transmitted from the clutch housing 193 to the first clutch 324 or the second clutch 322. The first transmission clutch 324 transmits torque between the propulsion source (not shown) and the first transmission input shaft 152. The second transmission clutch 322 transmits torque between the propulsion source (not shown) and the second transmission input shaft 154.

[0020] As described above, the second machine 150 may include a plurality of gears. In this example, there are two transmission input shafts, including a first transmission input shaft 152 and a second transmission input shaft 154. The second transmission input shaft 154 is hollow, while the first transmission input shaft 152 is solid and coaxial with the second transmission input shaft 154. For example, the first transmission input shaft 152 may have a plurality of fixed gears. For example, the first transmission input shaft 152 may include a first fixed gear 172 for receiving the first gear 160, a third fixed gear 161 for receiving the third gear 162, and a fifth fixed gear 163 for receiving the fifth gear 164. In other words, the first transmission input shaft 152 may be selectively connected to a plurality of odd-numbered gears. The second transmission input shaft 154 may include a second fixed gear 165 for receiving the second gear 166 or the reverse gear 167, and may also include a fourth fixed gear 168 for receiving the fourth gear 169 or the sixth gear 170. It will be appreciated that the first transmission input shaft 152 and the second transmission input shaft 154 may be connected to the first clutch 324 and the second clutch 322, respectively, via shaft spikes (not shown) on the outside of the shafts. In a normal stationary state, each of the first clutch 324 and the second clutch 322 is maintained in an open state, such as by a spring (not shown), etc., so that when each clutch is in an open state, no torque from the propulsion source can be transmitted to the first transmission input shaft 152 or the second transmission input shaft 154. In response to closing the first clutch 324, the propulsion source torque can be transmitted to the first transmission input shaft 152, and in response to closing the second clutch 322, the propulsion source torque can be transmitted to the second transmission input shaft 154. During normal operation, the controller 212 can ensure that only one clutch is fully closed at any given time.

[0021] The second machine 150 may also include a first laying shaft 180 and a second laying shaft 181. The gears on the first laying shaft 180 and the second laying shaft 181 are not fixed but can rotate freely. In the example of the DCT 150, the first laying shaft 180 includes a first gear 160, a second gear 166 and a sixth gear 170. The second laying shaft 181 includes a third gear 162, a fourth gear 169, a fifth gear 164 and a reverse gear 167. The first laying shaft 180 can transmit torque through the first output pinion 190, and the second laying shaft 181 can transmit torque through the second output pinion 191. The first output pinion 190 and the second output pinion 191 can transmit torque to the gear 192. In this way, the two laying shafts can transmit torque to the output shaft 193 through the first output pinion 190 and the second output pinion 191, wherein the output shaft 193 can transmit the torque to the differential (not shown), which can cause each driven wheel of the vehicle to rotate at a different speed, such as when performing a turning maneuver.

[0022] As described above, each of the first gear 160, the second gear 166, the third gear 162, the fourth gear 169, the fifth gear 164, the sixth gear 170, and the reverse gear 167 is not fixed to the layup shaft, but can rotate freely. Therefore, a sleeve including a synchronizer can be used to match each gear to the speed of the layup shaft, and can further be used to lock the gears. In the DCT 150 example, four sleeves including synchronizers are illustrated, for example, a first synchronizer 182, a second synchronizer 183, a third synchronizer 184, and a fourth synchronizer 185. The first synchronizer 182 includes a corresponding first selection fork 195, the second synchronizer 183 includes a corresponding selection fork 196, the third synchronizer 184 includes a corresponding third selection fork 197, and the fourth synchronizer 185 includes a corresponding fourth selection fork 198. Each selection fork can move each corresponding sleeve and synchronizer to lock one or more gears to the layup shaft, or unlock one or more gears from the layup shaft. For example, the first synchronizer 182 can be used to lock the first gear 160. The second synchronizer 183 can be used to lock the second gear 166 or the sixth gear 170. The third synchronizer 184 can be used to lock the third gear 162 or the fifth gear 164. The fourth synchronizer 185 can be used to lock the fifth gear 169 or the reverse gear 167. Under each condition, the movement of the synchronizer can be completed by the selection fork (such as 195, 196, 197 and 198), and the selection fork moves each synchronizer to the desired position through the actuator (such as a hydraulic cylinder) 114-120.

[0023] The movement of the selector fork synchronizer can be achieved through the controller 212 and the shift fork actuators (cylinders) 114-120. The controller 212 can collect input signals from various sensors, evaluate the inputs and control various actuators accordingly. The input signals used by the transmission controller may include, but are not limited to, transmission range (P / R / N / D / S / L, etc.), vehicle speed, ambient temperature, brake input, and transmission input shaft speed (first transmission input shaft 152 and second transmission input shaft 154). The controller 212 can control the actuators through open-loop control, closed-loop control, and adaptive control. For example, adaptive control allows the controller 212 to identify and adapt to the clutch engagement point, clutch friction coefficient, and the position of the synchronizer assembly.

[0024] The function of the second machine 150 can be understood as described herein. For example, when the first clutch 324 is closed by the actuator 320, the engine torque can be provided to the first transmission input shaft 152. When the first clutch 324 is closed, it can be understood that the second clutch 322 is open, and vice versa. Depending on the gear locked when the first clutch 248 is closed, power can be transmitted to the first laying shaft 180 or the second laying shaft 181 through the first transmission input shaft 152, and can be further transmitted to the output shaft 193 through the first pinion 190 or the second pinion 191. Alternatively, when the second clutch 322 is closed by the actuator 318, power can be transmitted to the first laying shaft 180 or the second laying shaft 181 (depending on which gear is locked) through the second transmission input shaft 154, and can be further transmitted to the output shaft 193 through the first pinion 190 or the second pinion 191. It is understood that when torque is transmitted to one shaft (such as the first output shaft 180), the other shaft (such as the second output shaft 181) may continue to rotate, even if only one shaft is directly driven by the input. More specifically, the unengaged shaft (such as the second output shaft 181) may continue to rotate because it is indirectly driven by the output shaft 193 and the respective pinion (such as 191).

[0025] Now please see Figure 2 , an example of a control system 200 for machine 100 is shown. Controller 212 may be in electrical communication with actuator 220 and sensor 222. Actuator 220 may include a valve (e.g., a valve that provides fluid (e.g., oil) to a hydraulic cylinder. Figure 1A and Figure 1B ), a hydraulic control valve for controlling a hydraulic cylinder, a motor (such as a motor) for adjusting the operating state of the machine 100, an electric pump, etc. The sensors may include but are not limited to pressure sensors, temperature sensors, ambient air temperature sensors, flow sensors, etc. The controller 212 may receive data from and provide data to a human-machine interface 230 (such as a touch screen or a display).

[0026] The controller 12 may include a processor 202, a read-only memory (non-temporary memory) 206, a random access memory 208, and input / output 205 (e.g., digital input, digital output, analog input, analog output, counter / timer, and communication port). The controller 12 may communicate with the sensor 222 via a controller area network or a dedicated line. In addition, as Figure 2 As shown, controller 12 may communicate with actuator 220 via a dedicated output channel via a controller area network 223 .

[0027] Now please see Figure 3 , a schematic diagram of a portion of the hydraulic system of machine 100 or machine 150 is shown. Figure 3 In the diagram, equipment and hydraulic lines are represented by solid lines. Electrical connections (such as wires) are represented by dashed lines.

[0028] The hydraulic system 300 includes an oil pan 302 in which fluid is stored. To reduce the number of hydraulic connections, the oil pan 302 is also located near the hydraulic control valve. An electric pump 306 can provide fluid from the oil pan 302 to hydraulic actuators (such as clutches and cylinders) and gears (not shown). In particular, when the charging valve 310 is in an open position, the electric pump provides fluid to the gears through the orifice 314. The charging valve 310 is a two-position valve, which is shown in a closed position in which the flow of fluid from the electric pump 306 through the conduit 350 into the orifice 314 is blocked. Closing the charging valve 310 allows fluid to flow from the electric pump and through the check valve 308, so that the fluid can fill the accumulator 304, thereby overcoming the closing force in the check valve 308. On the other hand, when the charging valve 310 is open, the fluid follows the path of least resistance through the charging valve 310 and the one-way valve 312 to the orifice 314, so that the closing force of the one-way valve 308 is not overcome.

[0029] Fluid flowing through conduit 352 may flow to one or more clutches (e.g., 322 and 324), accumulator 304, and / or one or more cylinders (e.g., 114-118). Hydraulic control valve 316 is a normally closed valve that controls fluid flow to clutch hydraulic control valve 318 and clutch hydraulic control valve 320. Line pressure of clutch 324 may be monitored by pressure sensor 340. Line pressure of clutch 322 may be monitored by pressure sensor 342. Hydraulic control valve 320 may independently control clutch 324. Hydraulic control valve 318 may independently control clutch 322.

[0030] Hydraulic control valve 326 is also a two-position normally closed valve that controls the flow of fluid to cylinder hydraulic control valve 328, cylinder hydraulic control valve 330, and cylinder hydraulic control valve 332. Cylinder hydraulic control valve 328 controls cylinder 114 individually. Cylinder hydraulic control valve 330 controls cylinder 116 individually. Cylinder hydraulic control valve 332 controls cylinder 118 individually. The cylinder hydraulic control valves can be adjusted to provide bidirectional control of cylinders 114-116. Controller 212 can adjust the position of the hydraulic valves, the speed of the electric pump, and monitor various pressures in the system.

[0031] In one example, the electric pump 306 includes a current sensor 362 for determining the current value consumed by the electric pump 306. The electric pump 306 can communicate the current value or torque value generated by the electric pump 306 via a controller area network (CAN) bus 355 or other communication means. The pressure in the accumulator 304 can be sensed by a sensor 360 and communicated to the controller 212.

[0032] therefore, Figure 1A-3 The system provides a hydraulic system including: one or more hydraulic actuators; an electric pump; and an accumulator, the accumulator being selectively hydraulically coupled to the one or more hydraulic actuators. Figure 1A-3 A hydraulic system is provided, comprising: one or more hydraulic actuators; an electric pump; an accumulator, the accumulator selectively coupled to the one or more hydraulic actuators and the electric pump in a hydraulic manner; a pressure sensor; and a controller, comprising a non-transitory computer-readable medium having executable instructions, the instructions causing the controller to adjust the operation of the electric pump in response to the output of the pressure sensor during a first condition, and to adjust the operation of the electric pump in response to a pressure estimate based on an accumulator volume model during a second condition. In a first example, the system includes a first condition in which the pressure sensor is not degraded and a second condition in which the pressure sensor is degraded. In a second example, which may include the first example, the system includes the volume model including a fixed volume degradation rate. In a third example, which may include one or both of the first and second examples, the system further includes one or more hydraulic actuators, wherein the volume model compensates for actuation of the one or more hydraulic actuators. In a fourth example, which may include one or more of the first to third examples, the system further includes additional instructions to activate the electric pump based on the pressure estimate output based on the accumulator volume model. In a fifth example, which may include one or more of the first to fourth examples, the system further includes additional instructions for adjusting the rotational speed of the electric pump to a threshold speed. In a sixth example, which may include one or more of the first to fifth examples, the system further includes additional instructions for deactivating the electric pump based on the amount of current delivered to the electric pump.

[0033] Now watch Figure 4 , Figure 4 The relationship between the electric pump torque (Newton-meters (Nm)) and the accumulator pressure (bar) is shown. The vertical axis represents the pump torque, and the pump torque increases in the direction of the vertical axis arrow. The horizontal axis represents the accumulator pressure, and the accumulator pressure increases in the direction of the horizontal axis arrow. The solid line 402 represents the electric pump torque and the accumulator pressure (such as Figure 3 304) The relationship between the pressures.

[0034] The pressure in the accumulator may not be reliable between p0 and p1. For a specific fluid temperature, the pressure in the accumulator between p1 and p2 may be more accurate and repeatable. The torque of the pump reaches its maximum around pressure p2, so the system will not use pressures higher than p2.

[0035] Reference now Figure 5 , Figure 5 Shows that the Figure 1A-3 system and Figure 6 The method is combined with the provided operation sequence example. Specifically, Figure 6 An example of the operating sequence of an accumulator pressure sensor going from a non-degraded state to a degraded state is shown. Figure 5 The graphs in are temporally consistent and occur simultaneously.

[0036] Figure 5 The first graph at the top is a graph of accumulator pressure versus time. The accumulator pressure can be measured or estimated. The vertical axis represents accumulator pressure, and the accumulator pressure increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases from the left side of the graph to the right side of the graph.

[0037] Figure 5 The second graph from the top is a graph of the electric pump speed versus time. The vertical axis represents the electric pump speed, and the electric pump speed increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases from the left side of the graph to the right side.

[0038] Figure 5 The third graph from the top is a graph of pump torque versus time. The vertical axis represents pump torque, which increases in the direction of the vertical axis arrow. The horizontal axis represents time, which increases from the left side of the graph to the right side. The threshold pump torque 550 represented by a dashed line indicates that the pressure in the accumulator has reached the required level when the accumulator pressure sensor performance is degraded (e.g., the sensor does not output a signal or value indicating the actual pressure in the accumulator).

[0039] At time t0, the accumulator pressure sensor operates as expected. Therefore, the electric pump is activated or deactivated based on the output of the accumulator pressure sensor. In particular, after the electric pump is activated, it is commanded to reach a first speed at a first speed change rate based on the accumulator pressure being less than a threshold pressure. Once the speed of the electric pump reaches the first speed, the speed of the electric pump is reduced at a predetermined rate. When the accumulator pressure reaches the first threshold pressure, the electric pump is commanded to deactivate.

[0040] At time t1, the pressure in the accumulator measured by the pressure sensor is less than a minimum pressure threshold (not shown). Therefore, the electric pump is activated and increases in speed at a first ramp rate. As the pump speed increases and the fluid in the accumulator fills, the torque of the electric pump also increases. The pressure in the accumulator also begins to increase. Between time t1 and time t2, the pressure in the accumulator reaches a maximum pressure threshold. Therefore, the electric hydraulic pump is deactivated and the pressure in the accumulator begins to decrease after reaching a peak.

[0041] At time t2, the pressure sensor reading the accumulator pressure will deteriorate. Therefore, a time-based accumulator pressure model or a volume-based accumulator pressure model can be enabled to estimate the pressure in the accumulator. In this example, a time-based model is used to estimate the accumulator pressure.

[0042] The most recently valid accumulator pressure value is seeded as an initial condition for the time model. The pressure in the accumulator is adjusted based on time and the operating state of the electric pump. The electric pump is activated when the time-based pressure in the accumulator is less than the minimum accumulator threshold. The speed of the electric pump is increased at a second rate that is lower than the speed of the hydraulic pump when the accumulator pressure sensor is not degraded. In addition, the speed of the electric pump is increased at a second rate that is lower than the speed of the electric pump when the accumulator pressure sensor is not degraded. Reducing the speed target value and the speed increase rate helps reduce the possibility of rapid changes in current provided to the electric pump, thereby avoiding the possibility of surges in current and hydraulic pump torque.

[0043] At time t3, the estimated pressure in the accumulator is less than the minimum threshold accumulator pressure, so the electric pump is activated and its speed is increased to a second threshold speed. When the electric pump torque is greater than the threshold pump torque 550, the electric pump is deactivated to save energy and avoid an overpressure condition. Between time t2 and time t4, the electric pump is cycled on and off several times depending on the estimated pressure in the accumulator.

[0044] At time t4, the accumulator volume-based pressure estimate of the accumulator is activated and the time-based accumulator pressure estimate is deactivated. The accumulator volume-based pressure estimate initial pressure is seeded with the most recent accumulator pressure estimate in the time-based accumulator pressure estimate. The volume value of the accumulator volume-based pressure estimate (e.g., the estimated volume of fluid in the accumulator) may decrease due to actuation of the hydraulic actuator and leakage of valves and seals. The accumulator volume-based pressure estimate may also increase as the volume of fluid pumped into the accumulator by the electric hydraulic pump increases.

[0045] At time t5, the accumulator pressure estimate based on the accumulator volume decreases to a minimum pressure, thereby activating the electric pump. The electric pump increases speed at a second rate upon reaching a second desired pump speed. The torque of the electric pump begins to increase shortly after time t5. Once the torque of the electric pump reaches the threshold pump torque 550, the electric pump is deactivated to maintain system efficiency and reduce the possibility of overpressure.

[0046] In this way, an estimate of the pressure in the accumulator can be determined based on a time-based model or a volume-based model. The pressure in the accumulator can be controlled by activating and deactivating the electric pump based on the accumulator pressure estimate. As a result, the hydraulic system can be supplied with fluid to allow it to continue operating and to shut down in an orderly manner.

[0047] Now please see Figure 6 , a flow chart of a method 600 of operating a hydraulic system having an accumulator pressure sensor is shown. Figure 6 The method can be used with Figure 1A-3 In addition, Figure 6 At least a portion of the method may be stored as executable instructions in a non-transitory memory of a computing system (eg, controller 212 ), while other portions of the method may be executed by the computing system transforming the operating states of devices and actuators in the physical world. Figure 6 The method may be executed by a controller at predetermined time intervals (eg, 10 milliseconds).

[0048] At 602, method 600 adjusts the output (e.g., flow) of the electric pump to achieve a desired pressure in the hydraulic system accumulator. In one example, when the pressure in the accumulator is greater than or equal to the desired pressure in the accumulator, the electric pump is deactivated. When the pressure in the accumulator is less than Figure 5 When the electric pump is activated, the speed of the electric pump may increase to a first speed change rate, and the speed of the electric pump may increase to a first speed. Figure 3 360 ) determines the pressure in the accumulator. Method 600 proceeds to 604 .

[0049] At 604, method 600 determines whether the pressure sensor is degraded. In one example, if the pressure indicated by the pressure sensor is outside a predetermined pressure range, method 600 may determine that the pressure sensor is degraded. Method 600 may also determine that the pressure sensor is degraded if the pressure sensor does not respond to the pressure reading in an expected manner. For example, if the electric hydraulic pump is activated and provides fluid to the accumulator, the accumulator pressure is expected to increase. If the accumulator pressure does not increase as expected, method 600 may determine that the pressure sensor is faulty. If method 600 determines that the pressure sensor is faulty, the answer is "yes" and method 600 proceeds to 606. Otherwise, the answer is no and method 600 returns to 602.

[0050] At 606, method 600 determines whether accumulator pressure sensor mitigation is enabled. In one example, method 600 can determine whether accumulator pressure sensor mitigation is enabled based on a variable value stored in the controller memory. If method 600 determines that accumulator pressure sensor mitigation is enabled, the answer is "yes" and method 600 proceeds to 608. Otherwise, the answer is no and method 600 proceeds to 620.

[0051] At 620, method 600 turns off the electric pump, thereby stopping the hydraulic charge of the hydraulic system. In addition, method 600 may also notify the machine operator through a message on the human-machine interface that the hydraulic system is shutting down. Method 600 continues to exit.

[0052] At 608 , method 600 retains the most recent pressure value of the degraded pressure sensor and stores the pressure value in memory. Method 600 proceeds to 610 .

[0053] At 610, method 600 converts the most recent pressure value from the pressure sensor into a fluid volume value stored in the accumulator. In one example, method 600 may reference a table or function stored in a controller (e.g., Figure 7 The table or function outputs the volume of fluid stored in the accumulator. The values ​​in the table or function may be determined empirically by monitoring the pressure in the accumulator while increasing the volume of fluid in the accumulator and the temperature of the fluid in the accumulator. The method 600 may also adjust the estimated volume of fluid stored in the accumulator based on leakage and volume loss caused by driving a hydraulic actuator (e.g., a cylinder or a clutch). The volume of fluid stored in the accumulator may be estimated by the following equation: EHAV = hav(acctemp, accpres) - havl(Fflow, acctemp) - haval(Estflow, acctemp) where EHAV is the estimated fluid volume in the accumulator, HAV is a function (e.g., a model) that returns the volume of fluid stored in the accumulator, acctemp is the temperature of the fluid stored in the accumulator, accpress is the pressure of the fluid stored in the accumulator, HAVL is a function that returns the volume loss of the accumulator due to leakage within one execution cycle of the method 600, Fflow is an estimated leakage flow rate that depends on the fluid temperature. Haval is a function that returns the volume loss of fluid in the accumulator due to the actuation of the hydraulic actuator within one execution cycle of the method 600 (e.g., 10 milliseconds), and Estflo w is the estimated flow rate into the actuator piston, which depends on the fluid temperature and the actuator being controlled by the current application. Once the estimated volume of fluid stored in the accumulator is determined, the pressure and temperature of the fluid stored in the accumulator are calculated by referencing a function or table (e.g. Figure 7 After the pressure of the fluid stored in the accumulator is determined, method 600 proceeds to 612 .

[0054] At 612, method 600 determines whether the pressure of the fluid in the accumulator determined in step 610 is greater than a threshold pressure. If so, the answer is yes and method 600 proceeds to 614. Otherwise, the answer is no and method 600 returns to 610 where the volume and pressure are recalculated.

[0055] At 614, method 600 starts the electric pump and increases the rate of change of speed at a second rate that is less than the first rate at which the speed of the pump increases when the pressure sensor is not degraded. Method 600 also adjusts the speed of the electric pump to a second speed that is less than the first speed. Increasing the speed of the electric pump may increase the fluid in the accumulator by adding additional fluid to the accumulator.

[0056] To ensure that more accurate line pressure is reported to other parts of the application system, method 600 also estimates the increase in the volume of fluid stored in the accumulator by the electric pump. In one example, method 600 estimates the increase in the volume of fluid stored in the accumulator based on the operating conditions of the electric pump (such as speed, temperature, etc.). In one example, method 600 estimates the increase in the volume of fluid stored in the accumulator according to the following formula: ΔAV=p(acctemp,n,dt) Where ΔAV is the change in volume of fluid added to the accumulator, p is the function of the return volume, acctemp is the temperature of the fluid stored in the accumulator, n is the speed of the electric pump, and dt is the time interval between executions of method 600. Function p can be an equation or a table stored in the controller memory filled with empirically determined volume values.

[0057] Method 600 can also monitor the torque of the electric pump. In one example, the current value flowing to the electric pump is converted into the torque output value of the electric pump by the following formula: EPT=g(pumcur,pumtem,n) Where EPT is the torque of the electric pump and g is the function that returns the torque of the electric pump (e.g. Figure 8 ), pumpur is the current entering the electric pump, pumtem is the temperature of the electric pump, and n is the speed of the electric pump. Method 600 proceeds to 616 and 622.

[0058] At 622, method 600 determines whether the charging time of the accumulator is greater than a threshold time. In one example, method 600 can track the amount of time that the electric pump has been activated recently to determine the amount of time that the accumulator charging has been activated. If method 600 determines that the accumulator charging has exceeded the threshold time, the answer is "yes" and method 600 proceeds to 620. Otherwise, the answer is no and method 600 returns to 614.

[0059] At 616, method 600 determines whether the torque output of the electric pump exceeds a threshold torque amount and whether the duration exceeds a threshold time. If so, the answer is "yes" and method 600 proceeds to 618. Otherwise, the answer is no and method 600 returns to 614.

[0060] At 618, method 600 stops the flow of current to the electric pump, thereby deactivating the pump. Method 600 also opens the charging valve (e.g. Figure 3 The method 600 returns to 610 where the pressure can be converted to a volume of fluid stored in the accumulator for use in an accumulator volume model.

[0061] In this way, when the pressure sensor of the hydraulic system fails, the amount of oil stored in the accumulator can be adjusted according to the oil consumption and leakage. The oil amount can be converted into an estimated pressure value of the oil in the accumulator, and the electric pump can be started or shut down according to the estimated pressure value of the oil.

[0062] therefore, Figure 6A method for operating a hydraulic system is provided, the method comprising: adjusting the operation of a pump according to an output of a pressure sensor indicating a pressure in an accumulator; and adjusting the operation of the pump according to a current value delivered to the pump and an indication of degradation of the pressure sensor. In a first example, the method comprises: adjusting the operation of the pump according to the pressure sensor comprises adjusting the rotational speed of the pump to a first threshold speed. In a second example, which may include the first example, the method comprises: adjusting the operation of the pump in response to the pressure sensor comprises adjusting the rate of change of the rotational speed of the pump to a first rate of change. In a third example, which may include one or both of the first and second examples, the method comprises: adjusting the operation of the pump in response to the amount of current delivered to the pump and an indication of degradation of the pressure sensor comprises adjusting the rotational speed of the pump to a second threshold speed, the second threshold speed being lower than the first threshold speed. In a fourth embodiment, which may include one or more of the first to third embodiments, the method comprises: adjusting the operation of the pump in response to the amount of current delivered to the pump and an indication of degradation of the pressure sensor comprises adjusting the rate of change of the rotational speed of the pump to a second rate of change, the second rate of change being lower than the first rate of change. In a fifth embodiment, which may include one or more of the first to fourth embodiments, the method includes wherein adjusting the operation of the pump in response to the amount of current delivered to the pump and the indication of degradation of the pressure sensor includes stopping the pump in response to the current delivered to the pump exceeding a threshold. In a sixth example, which may include one or more of the first to fifth examples, the method further includes closing the charging valve to direct fluid flow from the pump to the accumulator in response to the pressure within the accumulator being less than an estimate of a threshold pressure. In a seventh example, which may include one or more of the first to sixth examples, the method further includes deactivating the pump in response to a charging time being longer than a threshold amount of time, wherein the charging time refers to an amount of time from when the charging valve was last closed until when the pressure estimate exceeds the threshold pressure.

[0063] Figure 6 The method also provides a method for operating a hydraulic system, the method comprising: adjusting the operation of a pump based on the output of a pressure sensor, the pressure sensor indicating the pressure in an accumulator; and adjusting the operation of the pump based on a pressure estimate based on the volume of fluid stored in the accumulator. In a first example, the method comprises: adjusting the operation of the pump in response to the pressure estimate based on the volume of fluid stored in the accumulator comprises activating the pump. In a second example, which may include the first example, the method comprises adjusting the volume of fluid stored in the accumulator based on a fixed volume degradation rate. In a third example, which may include one or both of the first and second examples, the method comprises adjusting the volume of fluid stored in the accumulator based on the drive of an actuator. In a fourth example, which may include one or more of the first to third examples, the method further comprises deactivating the pump based on the magnitude of the current supplied to the pump.

[0064] See also Figure 7, the figure shows the relationship between the volume of fluid stored in the hydraulic accumulator and the pressure of the fluid stored in the hydraulic accumulator. The relationship can be stored in a memory cell array of the controller and can be indexed or referenced by temperature and fluid volume or temperature and fluid pressure.

[0065] Graph 700 includes a vertical axis representing the volume of fluid stored in the hydraulic accumulator, with the volume increasing in the direction of the arrow on the vertical axis. Graph 700 also includes a horizontal axis representing the pressure of the fluid stored in the hydraulic accumulator, with the pressure increasing in the direction of the arrow on the horizontal axis. Graph 700 also includes a horizontal axis representing the temperature of the fluid stored in the hydraulic accumulator, with the temperature increasing in the direction of the arrow on the horizontal axis. Surface 702 represents the relationship between the volume of the fluid in the accumulator, the pressure of the fluid in the accumulator, and the temperature of the fluid in the accumulator.

[0066] See also Figure 8 , the relationship between the motor current, the motor torque and the temperature of the fluid in the accumulator is shown in the figure. The relationship can be stored in a memory cell array of the controller and can be indexed or referenced by the temperature and volume or the temperature and pressure of the fluid.

[0067] Graph 800 includes a vertical axis representing the motor current (e.g., the current consumed by the motor) of the electric hydraulic pump, with the motor current increasing in the direction of the arrow on the vertical axis. Graph 800 also includes a horizontal axis representing the motor torque of the electric hydraulic pump, with the motor torque increasing in the direction of the arrow on the horizontal axis. Graph 800 also includes a horizontal axis representing the temperature of the fluid stored in the hydraulic accumulator, with the temperature increasing in the direction of the arrow on the horizontal axis. Graph 802 illustrates the relationship between the motor current, the motor torque, and the temperature of the fluid in the accumulator.

[0068] Please note that the control and estimation routine examples included herein can be used in various vehicle or machine system configurations. The control methods and routines disclosed herein can be stored as executable instructions in a non-transitory memory and can be executed by a control system including a controller combined with various sensors, actuators and other machine hardware. In addition, some methods may be physical actions taken in the real world to change the state of the device. The specific routines described herein may represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc. Therefore, the various actions, operations and / or functions illustrated can be performed in the order shown, can be performed in parallel, or omitted in some cases. Similarly, the processing order is not necessarily required to achieve the features and advantages of the examples described herein, but is only for ease of illustration and description. Depending on the specific strategy used, one or more of the illustrated actions, operations and / or functions can be repeatedly performed. In addition, the described actions, operations and / or functions can graphically represent the code to be programmed into the non-transitory memory of a computer-readable storage medium in an engine control system, wherein the described actions are implemented by executing instructions in a system including various engine hardware components combined with an electronic controller. If necessary, one or more method steps described herein can be omitted.

[0069] It is understood that the configurations and routines disclosed herein are exemplary in nature, and these specific examples are not limiting, as there may be many variations. For example, the above technology may be applied to cranes, excavators, scrapers, and other systems that include linked or coupled components.

[0070] The following claims particularly point out certain combinations and subcombinations regarded as novel and non-obvious. The claims may refer to "an" element or a "first" element or the equivalent. The claims may be construed to include one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amendment of the present claims or by presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, are also deemed to be included in the subject matter of the present disclosure.

Claims

1. A method of operating a hydraulic system, comprising: According to the output of the accumulator pressure sensor, the operation of the pump is adjusted; as well as Operation of the pump is adjusted based on the amount of current delivered to the pump and the indication of degradation of the pressure sensor. 2 . The method of claim 1 , wherein adjusting operation of a pump based on the output of the pressure sensor comprises adjusting a rotational speed of the pump to a first threshold speed. 3 . The method of claim 2 , wherein adjusting the operation of the pump according to the output of the pressure sensor comprises adjusting a rate of change of a rotational speed of the pump to a first rate of change.

4. The method of claim 3, wherein adjusting the operation of the pump based on the amount of current delivered to the pump and the indication of degradation of the pressure sensor includes adjusting the rotational speed of the pump to a second threshold speed, the second threshold speed being lower than the first threshold speed.

5. The method of claim 4, wherein adjusting the operation of the pump based on the amount of current delivered to the pump and the degradation indication of the pressure sensor further includes adjusting the rate of change of the rotational speed of the pump to a second rate of change, the second rate of change being less than the first rate of change.

6. The method of claim 1, wherein adjusting operation of the pump based on the amount of current delivered to the pump and an indication of degradation of the pressure sensor includes discontinuing use of the pump in response to the current delivered to the pump exceeding a threshold. 7 . The method of claim 6 , further comprising closing a charging valve to direct fluid flow from the pump to the accumulator in response to the estimate of pressure within the accumulator being less than a first threshold pressure.

8. The method of claim 7 further comprising disabling use of the pump in response to a filling time being longer than a threshold amount of time, wherein the filling time is a duration starting from when the filling valve was last closed and ending when the pressure estimate exceeds a second threshold pressure.

9. Hydraulic system, including: one or more hydraulic actuators; Electric pump; an accumulator selectively hydraulically connected to the one or more hydraulic actuators and the electric pump; Pressure sensor; as well as A controller includes a non-transitory computer readable medium having executable instructions that cause the controller to adjust the operation of the electric pump according to the output of the pressure sensor under a first condition and adjust the operation of the electric pump according to a pressure estimate based on an accumulator volume model under a second condition. 10 . The hydraulic system of claim 9 , wherein the first condition is that the pressure sensor is not degraded, and the second condition is that the pressure sensor is degraded.

11. The hydraulic system of claim 10, wherein the volume model includes a fixed volume degradation rate.

12. The hydraulic system of claim 11, further comprising one or more hydraulic actuators, wherein the volume model compensates for actuation of the one or more hydraulic actuators.

13. The hydraulic system of claim 12, further comprising additional instructions for activating the electric pump based on a pressure estimate based on output of the volume model.

14. The hydraulic system of claim 13, further comprising additional instructions for adjusting the rotational speed of the electric pump to a threshold speed.

15. The hydraulic system of claim 14, further comprising additional instructions for deactivating the electric pump based on the amount of current delivered to the electric pump.

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