Redundant steering system and method and machine therefor

Abstract

A redundant steering system includes a primary power source, a secondary power source, first and second pumps respectively operably coupled to the primary and secondary power sources to output first and second hydraulic fluid supplies respectively to a steering cylinder based on operation of the primary and secondary power sources, a first and second pair of selector valves respectively coupled to the first and second pumps, and a pressurization circuit coupled to respective control inputs of the first and second pairs of selector valves to selectively supply hydraulic fluid to the control inputs of the first and second pairs of selector valves to prevent hydraulic fluid from only one of the first and second pumps from being provided to the steering cylinder and to provide hydraulic fluid from only one of the other of the first and second pumps to the steering cylinder.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a redundant steering system and method and machine thereof, in particular, a redundant meterless electro-hydraulic (EH) steering system. BACKGROUND

[0002] Conventional meterless EH steering systems can not include a control valve for controlling the flow of hydraulic fluid in the steering system, but rather can have a pump directly connected to a steering cylinder to provide hydraulic fluid to the steering cylinder. Such steering systems can not have a backup means of supplying hydraulic fluid to the steering cylinder, which can be particularly problematic in vehicles configured to travel at 20 kilometers per hour or higher.

[0003] Korean Patent Document KR 10-0542607 (“KR‘607 Patent Document”) describes a power assisted steering system equipped with a fail-safe. According to the KR‘607 Patent Document, when a problem is detected with the main portion fluid supply, the supplemental portion fluid supply is operated to supply fluid to a steering gear box connected to a power cylinder. However, the KR‘607 Patent Document should not be understood as describing a meterless EH steering system having different selector valve means to selectively control the flow of fluid through the main portion fluid supply and the supplemental portion fluid supply. SUMMARY

[0004] In one aspect, the present disclosure provides or implements a redundant meterless electro-hydraulic steering system. The redundant meterless electro-hydraulic steering system can include a main power source that is an engine, an auxiliary power source, a first pump operably coupled to the main power source and configured to output a first hydraulic fluid supply to at least one steering cylinder based on operation of the main power source, a second pump operably coupled to the auxiliary power source and configured to output a second hydraulic fluid supply to the at least one steering cylinder based on operation of the auxiliary power source, a first pair of selector valves coupled to the first pump, a second pair of selector valves coupled to the second pump, and a pressurized circuit coupled to respective control inputs of the first and second pairs of selector valves and configured to selectively supply hydraulic fluid to the control inputs of the first and second pairs of selector valves to prevent hydraulic fluid from being provided to the at least one steering cylinder from only one of the first and second pumps and to provide hydraulic fluid to the at least one steering cylinder from only one of the other of the first and second pumps.

[0005] In another aspect, a wheeled machine may be provided or implemented. The wheeled machine may include: a pair of steering cylinders configured to control steering motion associated with the wheeled machine; a primary power source for the wheeled machine, the primary power source being an engine; an auxiliary power source; a first variable displacement pump operably coupled to the primary power source and configured to output a primary hydraulic fluid supply to the pair of steering cylinders based on operation of the primary power source; a second variable displacement pump operably coupled to the auxiliary power source and configured to output an auxiliary hydraulic fluid supply to the pair of steering cylinders based on operation of the auxiliary power source; and a pump coupled to the first variable displacement pump. a first pair of selector valves for a variable displacement pump; a second pair of selector valves coupled to a second variable displacement pump; and a pressurizing circuit coupled to respective control inputs of the first and second pairs of selector valves and configured to selectively supply hydraulic fluid to the control inputs of the first and second pairs of selector valves to prevent hydraulic fluid from only one of the first and second variable displacement pumps from being supplied to the pair of steering cylinders and to supply hydraulic fluid from only one of the other of the first and second variable displacement pumps to the pair of steering cylinders. The primary and auxiliary hydraulic fluid supplies to the pair of steering cylinders may be unmetered.

[0006] And, in another aspect, a method can be implemented, the method comprising: providing a main power source; providing an auxiliary power source; providing a first variable displacement pump, the first variable displacement pump being operably coupled to the main power source and being configured to output a first hydraulic fluid supply to at least one steering cylinder based on operation of the main power source; providing a second variable displacement pump, the second variable displacement pump being operably coupled to the auxiliary power source and being configured to output a second hydraulic fluid supply to the at least one steering cylinder based on operation of the auxiliary power source; providing a first selector valve device coupled to the first variable displacement pump and the second variable displacement pump; providing a second selector valve device coupled to the first variable displacement pump and the second variable displacement pump a selection valve device; and providing a pressurizing circuit, which is connected to the corresponding control inputs of the first selection valve device and the second selection valve device and is configured to selectively supply hydraulic fluid to the control inputs of the first selection valve device and the second selection valve device based on detection of a fault associated with the main power source and / or the first variable displacement pump or the auxiliary power source and / or the second variable displacement pump to prevent hydraulic fluid from only one of the first variable displacement pump and the second variable displacement pump from being provided to the at least one steering cylinder, thereby providing hydraulic fluid from only one of the other of the first variable displacement pump and the second variable displacement pump to the at least one steering cylinder.

[0007] Other features and aspects of the present disclosure will become apparent from the following description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a diagrammatic illustration of an exemplary machine.

[0009] Figure 2 is a schematic diagram of an exemplary electro-hydraulic steering system according to one or more embodiments of the disclosed subject matter.

[0010] Figure 3 is a schematic diagram of another exemplary electro-hydraulic steering system according to one or more embodiments of the disclosed subject matter. DETAILED DESCRIPTION

[0011] The present disclosure relates to a redundant steering system and a machine and method thereof, in particular to a redundant meterless electro-hydraulic (EH) steering system. The electro-hydraulic (EH) steering system may be referred to as a steer-by-wire steering system.

[0012] Referring now to the accompanying drawings, Figure 1 A side view of a machine 100 is shown, according to an embodiment of the disclosed subject matter.The machine 100, which may be a work machine, may include an electro-hydraulic steering system as disclosed herein.

[0013] Machine 100 may include an engine housing 102, an operator station 104, and a work implement 106, such as a bucket for digging and loading materials. In an example where machine 100 is a wheel loader, work implement 106 may be powered and controlled by a plurality of actuators, including a tilt actuator 108. Machine 100 may include front and rear ground-engaging devices, such as front wheels 110 and rear wheels 112 supporting machine 100. Engine housing 102 may include a power source, such as an engine 114, that may provide power to front wheels 110 and / or rear wheels 112. According to embodiments of the disclosed subject matter, machine 100 may be capable of traveling at speeds of 20 km / h or greater.

[0014] To drive the machine 100, the operator may manipulate one or more steering input devices that may be housed within the operator station 104. The input devices may be operated by extending and retracting hydraulic steering actuators or cylinders ( Figure 1116 and a rear end 118. A hydraulic steering actuator may extend between the front end 116 and the rear end 118 and may be configured to articulate the front end 116 relative to the rear end 118 about an articulation axis 120. Although an electro-hydraulic steering system is discussed with reference to an articulated working machine, the principles and systems described herein are equally applicable to more conventional (Ackermann) hydraulic steering systems that can rotate the wheels relative to the machine body to steer the machine. Accordingly, embodiments of the disclosed subject matter may relate to machines in the form of wheel loaders, trucks, motor graders, and the like.

[0015] Go to Figure 2 , this figure shows a schematic diagram of an exemplary electro-hydraulic steering system 200 according to one or more embodiments of the disclosed subject matter, which can be implemented in a machine, such as machine 100, according to embodiments of the disclosed subject matter. Generally, steering system 200 can control the supply of hydraulic fluid to and from one or more cylinders 150 to control the steering operation of machine 100.

[0016] System 200 may include a primary power source E, which may correspond to engine 114 discussed above, an auxiliary power source M, a first pump 210, and a second pump 230. Auxiliary power source M may be an electric motor (e.g., an electric motor) or a ground-driven power source driven by movement of a drive shaft corresponding to movement of corresponding wheels of machine 100. Each of first pump 210 and second pump 230 may be a variable displacement pump. Optionally, first pump 210 and second pump 230 may have the same or substantially the same configuration. The output flow of first pump 210 and second pump 230 per revolution, respectively, based on the operation of primary power source E and auxiliary power source M, may vary with variable displacement control of first pump 210 and second pump 230.

[0017] As shown, the first pump 210 can be operably coupled to a primary power source E, and the second pump 230 can be operably coupled to a secondary power source M. Operation of the primary power source E can cause the first pump 210 to operate, and the operation of the first pump 210 can cause hydraulic fluid (e.g., hydraulic oil) to be output from the first pump 210 (e.g., in the case of a variable displacement pump, output from any one of the ports and received by another of the ports). Similarly, operation of the auxiliary power source M can cause the second pump 230 to operate, and the operation of the second pump 230 can cause hydraulic fluid (e.g., hydraulic oil) to be output from the second pump 230 (e.g., in the case of a variable displacement pump, output from any one of the ports and received by another of the ports).

[0018] The hydraulic fluid output from the first pump 210 and the second pump 230 may be referred to as a first hydraulic fluid supply and a second hydraulic fluid supply, respectively, which may be selectively and optionally exclusively provided to one or more cylinders 150. Furthermore, according to one or more embodiments, the hydraulic fluid output from the first pump 210 may be referred to as a primary hydraulic fluid supply, and the hydraulic fluid output from the second pump 230 may be referred to as an auxiliary or even supplemental hydraulic fluid supply.

[0019] The hydraulic fluid output from the first pump 210 and / or the second pump 230 may be provided to the one or more cylinders 150 without being metered by a metering device (e.g., a metering valve). In fact, the system 200 may not have a metering device between the first pump 210 and / or the second pump 230 and the one or more cylinders 150. Therefore, the system 200 may be referred to or characterized as a meterless steering system.

[0020] The system 200 may further include a first selector valve device 220, a second selector valve device 240, and a pressurizing circuit 250. Figure 2 As shown, each of the first selector valve assembly 220 and the second selector valve assembly 240 can have a separate selector valve associated with the first pump 210 and the second pump 230, respectively. Alternatively, a separate selector valve of one selector valve assembly can be paired with a separate selector valve of another selector valve assembly, for example, because both selector valves are operably coupled to the same working portion of one or more cylinders 150.

[0021] The pressurizing circuit 250 may include a first or main pressurizing sub-circuit 260, a second or auxiliary pressurizing sub-circuit 270, and a control valve device 290. Generally, the pressurizing circuit 250 may be configured to selectively couple the outputs of the first and second pressurizing sub-circuit 260, 270, particularly the hydraulic fluids thereof, to the control valve device 290 so that the control valve device 290 selectively outputs the hydraulic fluid.

[0022] The first pressurizing sub-circuit 260 may include an electro-hydraulic actuator 261, a pressurizing pump 262, and a release valve 263. The first pressurizing sub-circuit 260 may be characterized as a low-pressure pressurizing system relative to the pressure of the hydraulic fluid from the first pump 210 because the pressure of the hydraulic fluid output by the first pressurizing sub-circuit 260 may be lower than the pressure of the hydraulic fluid output by the first pump 210.

[0023] The boost pump 262 can draw hydraulic fluid from the tank T, and the hydraulic fluid can eventually return to the tank T. Generally speaking, the boost pump 262 can provide hydraulic fluid for various control aspects of the system 200, including the control of the first pump 210. For example, the electro-hydraulic actuator 261 can be operated to control the displacement of the first pump 210 based on the hydraulic fluid output from the boost pump 262.

[0024] The output of the boost pump 262 may also be coupled to a release valve 263 and a dedicated valve 280. Flow from the boost pump 262 may be routed to and through the dedicated valve 280, or, if the pressure of the flow exceeds a threshold of the release valve 263 (e.g., because the dedicated valve 280 blocks flow from the boost pump 262), routed to and through the release valve 263 and on to the storage tank T.

[0025] Similarly, the second pressurizing sub-circuit 270 may have an electro-hydraulic actuator 271, a pressurizing pump 272, and a release valve 273. The second pressurizing sub-circuit 270 may be characterized as a low-pressure pressurizing system relative to the pressure of the hydraulic fluid from the second pump 230 because the pressure of the hydraulic fluid output by the second pressurizing sub-circuit 270 may be lower than the pressure of the hydraulic fluid output by the second pump 230.

[0026] The boost pump 272 can draw hydraulic fluid from the tank T, and the hydraulic fluid can eventually return to the tank T. Generally speaking, the boost pump 272 can provide hydraulic fluid for various control aspects of the system 200, including the control of the second pump 230. For example, the electro-hydraulic actuator 271 can operate to control the displacement of the second pump 230 based on the hydraulic fluid output from the boost pump 272.

[0027] The output of the charge pump 272 can also be coupled to a relief valve 273 and a dedicated valve 280. Flow from the charge pump 272 can be routed to and through the dedicated valve 280, or, if the pressure of the flow exceeds a threshold of the relief valve 273 (e.g., because the dedicated valve 280 blocks flow from the charge pump 272), routed to and through the relief valve 273 and on to the tank T. Optionally, the relief valve 263 and the relief valve 273 can have the same pressure threshold setting. Alternatively, the pressure threshold settings can be different, for example, one (e.g., the relief valve 263) can be set higher than the other (e.g., the relief valve 273) to prevent the flow of hydraulic fluid from the first and second pressurized sub-circuits 260, 270 from switching to the control valve arrangement 290.

[0028] A dedicated valve 280, which may be referred to as a logic element or resolver valve, may receive or be coupled to the outputs of the first pressurized sub-circuit 260 and the second pressurized sub-circuit 270. The output of the dedicated valve 280 may be provided to or coupled to a control valve arrangement 290.

[0029] According to one or more embodiments, the dedicated valve 280 can be configured to block or seal one of its inputs (i.e., from either the first pressurized sub-circuit 260 or the second pressurized sub-circuit 270) to allow hydraulic fluid to flow from the other of the inputs (i.e., the other of the first pressurized sub-circuit 260 or the second pressurized sub-circuit 270) to its output. The permitted flow can be the flow of the hydraulic fluid with the greater pressure of the two flows. For example, the dedicated valve 280 can be comprised of a ball between two channels that can move in response to which input provides the higher pressure between the two channels to selectively connect one of the inputs to its output and seal the other of the two inputs to block flow. According to one or more embodiments, the permitted flow can be from the first pressurized sub-circuit 260 or the second pressurized sub-circuit 270 associated with whichever of the primary power source E / first pump 210 or the auxiliary power source M / second pump 230 is currently operating (thus, from the boost pump 262 or the boost pump 272, respectively).

[0030] In system 200, a control valve assembly 290, which may be a single control valve, i.e., comprised of or composed of only one control valve, may be coupled to the output of dedicated valve 280. According to one or more embodiments, control valve assembly 290 may be in the form of a solenoid valve, such as a spring-biased solenoid valve. Thus, depending on the state of dedicated valve 280, control valve assembly 290 may be selectively coupled to either first pressurized sub-circuit 260 or second pressurized sub-circuit 270.

[0031] Depending on the state of the control valve device 290, the output of the control valve device 290 can be coupled to the tank T or the control inputs of the first selector valve device 220 and the second selector valve device 240. Figure 2 In the illustrated unpowered state of the control valve assembly 290, it can be coupled to the tank T, and in the powered or energized state of the control valve assembly 290, it can be coupled to the control inputs of the first selector valve assembly 220 and the second selector valve assembly 240 (i.e., the upper frame moves downward to the lower position). Therefore, as long as the control valve assembly 290 is in the unpowered or non-actuated state, its output can be coupled to the tank T, and no hydraulic fluid is output to the control inputs of the first selector valve assembly 220 and the second selector valve assembly 240 to actuate their selector valves.

[0032] In the energized state, the control valve device 290 can supply hydraulic fluid from the first pressurized sub-circuit 260 or the second pressurized sub-circuit 270 to the control inputs of the first selector valve device 220 and the second selector valve device 240 (see the dashed lines 290 to 220, 240). Figure 2As shown in , each of the first selector valve device 220 and the second selector valve device 240 can be composed of two different selector valves. The selector valves of the first selector valve device 220 can be coupled to the first pump 210, in particular, the corresponding output of the first pump 210. Similarly, the selector valves of the second selector valve device 240 can be coupled to the second pump 230, in particular, the corresponding output of the second pump 230. Alternatively, each of the first selector valve device 220 and the second selector valve device 240 can be formed by a single selector valve coupled to the first pump 210 and the second pump 230 via corresponding lines.

[0033] The hydraulic fluid supplied from the control valve device 290 to the first and second selector valve devices 220 and 240 can control the respective states of the selector valves of the first and second selector valve devices 220 and 240 (see again the dashed lines 290 to 220 and 240). That is, supplying the hydraulic fluid from the control valve device 290 to the first and second selector valve devices 220 and 240 can cause their respective valves to change state.

[0034] The selector valve of the first valve assembly 220 can be out of phase with the selector valve of the second valve assembly 240. For example, in the system 200, the selector valve of the first valve assembly 220 can be open in an unpowered or rest position, i.e., allowing flow, to allow hydraulic fluid from the first pump 210 to flow to one or more cylinders 150, while the selector valve of the second valve assembly 240 can be closed in an unpowered or rest position, i.e., preventing flow, to prevent hydraulic fluid from the second pump 230 from flowing to one or more cylinders 150. When hydraulic fluid from the control valve assembly 290 is supplied to the control inputs of the first and second selector valve assemblies 220 and 240, i.e., energizing their respective selector valves, the state of the respective selector valves can be changed from open to closed or from closed to open, depending on their current state. Thus, the selector valve of the first valve assembly 220 can be closed, preventing hydraulic fluid from the first pump 210 from flowing to one or more cylinders 150, while the selector valve of the second valve assembly 240 can be opened, allowing hydraulic fluid from the second pump 230 to be supplied to the one or more cylinders 150.

[0035] For clarity, Figure 2 The system 200 can provide hydraulic fluid exclusively from the first pump 210 or the second pump 230 to one or more cylinders 150, with the corresponding first selector valve device 220 and the second selector valve device 240 actively allowing hydraulic flow or actively blocking hydraulic flow. Although the hydraulic flow is exclusively provided from the first pump 210 or the second pump 230, alternatively, as Figure 2As shown in , a portion of the flow path from the second pump 230 to the one or more cylinders 150 may overlap or be shared with a portion of the flow path from the first pump 210 to the one or more cylinders 150, even though hydraulic fluid is provided to the one or more cylinders 150 by only one of the first pump 210 or the second pump 230 at a time.

[0036] The system 200 may also include a plurality of check valves 202. According to one or more embodiments, the check valves 202 may be referred to as component check valves having a ball and spring configuration. Figure 2 As shown in FIG, the ends of the check valve 202 can be coupled together to the output of the dedicated valve 280 and the input of the control valve device 290. The other end of the check valve 202 can be connected to the respective lines leading from the first pump 210 and the second pump 230 to the one or more cylinders 150.

[0037] The system 200 may also include a plurality of release valves 203. Figure 2 As shown in FIG, the ends of the release valve 203 can be coupled together to the output of the dedicated valve 280 and the input of the control valve device 290. The other end of the release valve 203 can be connected to the respective lines leading from the first pump 210 and the second pump 230 to the one or more cylinders 150.

[0038] System 200 may also include a plurality of sensors configured to sense or detect operational characteristics of system 200. For example, system 200 may include a plurality of pressure sensors PS. Such sensors may be arranged to detect hydraulic pressure associated with various components of system 200, such as hydraulic flow at the outputs of first pump 210 and second pump 230 and at the inputs of control valve arrangement 290. System 200 may also include one or more position sensors, such as position sensor 211 and position sensor 231. Position sensor 211 may sense the position of first pump 210. Similarly, position sensor 231 may sense the position of second pump 230. More specifically, position sensors 211 and 231 may identify whether first pump 210 or second pump 230 is in an expected position. Additionally or alternatively, system 200 may include other types of sensors, such as a debris sensor configured to sense debris from first pump 210 or second pump 230.

[0039] The sensors can be coupled to electronics, such as control circuitry, a controller, or a processor, to determine a fault or failure condition of the system 200. For example, a low pressure reading from one of the pressure sensors PS can indicate a fault or failure associated with the primary power source E and / or the first pump 210 or the auxiliary power source M and / or the second pump 230, depending on where in the system 200 the pressure sensor PS associated with the signal is located.

[0040] Failure or malfunction of the sensor detection system 200 can be used to alert an operator of the machine 100 of the failure or malfunction and switch the flow of hydraulic fluid from being provided to the one or more cylinders 150 by the first pump 210 to being provided to the one or more cylinders by the second pump 230. Thus, upon detection of the failure or malfunction, a control signal can be provided to the control valve device 290 to actuate, as described above, which can cause hydraulic fluid to flow from the pressurized circuit 250 to the control inputs of the first and second selector valve devices 220, 240 to block hydraulic fluid from the first pump 210 from reaching the one or more cylinders 150 and to begin providing hydraulic fluid to the one or more cylinders 150 from the second pump 230.

[0041] Turning now to Figure 3 , Figure 3 A schematic of an exemplary electro-hydraulic steering system 300 is shown in accordance with one or more embodiments of the disclosed subject matter, which can be implemented in a machine, such as the machine 100, in accordance with embodiments of the disclosed subject matter. Generally, the steering system 300 can control the supply of hydraulic fluid to and from the one or more cylinders 150 to control steering operations of the machine 100.

[0042] The system 300 is similar to the system 200 discussed above, but notably, can be configured to provide hydraulic fluid to the one or more cylinders 150 from both the first and second pumps 210, 230 simultaneously. In this regard, the pressurized circuit 350 can include a control valve device 390 coupled to the control inputs of the first and second selector valve devices 220, 240.

[0043] Notably, the control valve device 390 can have a first control valve 392 (e.g., solenoid valve) and a second control valve 394 (e.g., solenoid valve). The inputs of the first and second control valves 392, 394 can be from the dedicated valve 280 and the outputs of each of the first and second control valves 392, 394 can output to the tank T, particularly when the first and second control valves 392, 394 are not powered or in a resting state. As Figure 3As shown in FIG, when the first control valve 392 and the second control valve 394 are in an unpowered or static state, the first selector valve assembly 220 and the second selector valve assembly 240 can be unpowered or static, and thus open to allow hydraulic fluid from both the first pump 210 and the second pump 230 to be provided to the one or more cylinders 150. Generally, each of the first pump 210 and the second pump 230, when operating alone, can supply sufficient hydraulic fluid to operate the one or more cylinders 150 in the auxiliary or safety steering mode. According to one or more embodiments, each of the first pump 210 and the second pump 230 can provide half of the total amount of hydraulic fluid required to control the one or more cylinders 150 in the normal operating mode. Alternatively, the first pump 210, in the form of the main pump 210, can provide more than half (e.g., 60%) of the amount of hydraulic fluid required to control the one or more cylinders 150.

[0044] If one of the first pump 210 or the second pump 230 (or its associated components) malfunctions or fails, the system 300 can detect such malfunction or failure using sensors (e.g., one or more pressure sensors PS) and send a control signal to energize one of the first control valve 392 or the second control valve 394, thereby providing hydraulic fluid from the pressurized circuit 350 to the corresponding first selector valve device 220 or the second selector valve device 240 to close and prevent the hydraulic fluid from being provided to the one or more cylinders 150. The other of the first control valve 392 or the second control valve 394 can remain unpowered or in a static state to continue to provide hydraulic fluid to the one or more cylinders 150.

[0045] Industrial applicability

[0046] As described above, the present disclosure relates to a redundant steering system and machine and method thereof, and in particular, a redundant meterless electro-hydraulic (EH) steering system.

[0047] Such systems and methods can be implemented in a machine, such as machine 100, to meet certain industry requirements, such as standard ISO 5010, as such standards relate to machine speed (e.g., 20 km / h), fail-safe operation, and providing a redundant steering system. Embodiments of the disclosed subject matter can also improve efficiency by detecting a steering system failure or malfunction and switching to a backup steering configuration by shutting off the flow of hydraulic fluid associated with the primary power source in favor of the flow of hydraulic fluid associated with the auxiliary power source, or by shutting off the flow of hydraulic fluid associated with a failed or failed power source and leaving the flow of hydraulic fluid associated with a non-failed or failed power source.

[0048] Thus, embodiments of the disclosed subject matter may include a primary power source E, an auxiliary power source M, a first pump 210, and a second pump 230. The output flows of the first pump 210 and the second pump 230 per revolution of the operation of the primary power source E and the auxiliary power source M, respectively, may vary with variable displacement control of the first pump 210 and the second pump 230. The systems 200, 300 may also include a first selector valve device 220, a second selector valve device 240, and a pressurizing circuit 250, 350. The pressurizing circuit 250, 350 may include a first or primary pressurizing sub-circuit 260, a second or auxiliary pressurizing sub-circuit 270, and a control valve device 290, 390. Generally, the pressurizing circuit 250, 350 may be configured to selectively couple the outputs of the first and second pressurizing sub-circuits 260, 270, particularly the hydraulic fluids thereof, to the control valve devices 290, 390, so that the control valve devices 290, 390 selectively output the hydraulic fluids.

[0049] Depending on the state of the control valve devices 290, 390, the outputs of the control valve devices 290, 390 can be coupled to the tank T or the control inputs of the first and second selector valve devices 220, 240. In the unpowered state of the control valve devices 290, 390, they can be coupled to the tank T, and in the powered or energized state of the control valve devices 290, 390, they can be coupled to the control inputs of the first and second selector valve devices 220, 240. Therefore, as long as the control valve devices 290, 390 are in the unpowered or non-actuated state, their outputs can be coupled to the tank T, and no hydraulic fluid is output to the control inputs of the first and second selector valve devices 220, 240 to actuate their selector valves.

[0050] In the energized state, the control valve arrangement 290, 390 can supply hydraulic fluid from the first pressurized sub-circuit 260 or the second pressurized sub-circuit 270 to the control inputs of the first selector valve arrangement 220 and / or the second selector valve arrangement 240, depending on whether the hydraulic fluid is supplied from the first pressurized sub-circuit 260 or the second pressurized sub-circuit 270. Figure 2 System 200 or Figure 3 The hydraulic fluid from the control valve device 290, 390 to the first selector valve device 220 and / or the second selector valve device 240 can control the corresponding state of the selector valves of the first selector valve device 220 and the second selector valve device 240. That is, the hydraulic fluid provided from the control valve device 290, 390 to the first selector valve device 220 and / or the second selector valve device 240 can cause the corresponding valves thereof to change state. Figure 2, the first selector valve device 220 may be energized to close the corresponding selector valve and prevent flow from the first pump 210, and the second selector valve device 240 may be energized to open the corresponding selector valve to begin providing hydraulic fluid flow from the second pump 230. According to 3, both the first selector valve device 220 and the second selector valve device 240 may be initially opened to transfer hydraulic fluid from the first pump 210 and the second pump 230, respectively, and then one of the first selector valve device 220 or the second selector valve device 240 may be energized by one of the first control valve 392 or the second control valve 394 of the control valve device 390 to close the corresponding selector valve of the first selector valve device 220 or the second selector valve device 240, thereby preventing hydraulic fluid from the first pump 210 or the second pump 230.

[0051] Regarding the operation of the check valve 202, if one or more cylinders 150 moves in such a manner that the flow from the first pump 210 or the second pump 230 cannot keep up with the movement, the pressure of the hydraulic fluid supplied to the one or more cylinders 150 may drop and potentially cause lash. The check valve 202 may be configured to maintain the pressure in the supply line to the one or more cylinders 150 so that the pressure does not drop below (including not remain below) the pressure of the hydraulic fluid in the pressurizing circuit 250, 350. In this regard, if the pressure in the supply line to the one or more cylinders 150 drops below, or attempts to drop below, the pressure in the pressurizing circuit 250, 350, the pressure in the pressurizing circuit 250, 350 may cause the check valve 202 to open. Thus, the pressurizing circuit 250, 350 may make up the hydraulic fluid needed to prevent the one or more cylinders 202 from lashing out. On the other hand, if for some reason structure (e.g., the ground) is pressuring the steering linkage, which in turn presses one or more cylinders 150 in a desire to move faster than the amount of hydraulic fluid available from the first pump 210 and / or the second pump 230, supplemental hydraulic fluid may be provided from the pressurized circuit 250, 350 through the check valve 202.

[0052] Regarding operation of the release valves 203, if the connecting rod resists the pressure of the hydraulic fluid from the first pump 210 and / or the second pump 230, each release valve 203 may allow hydraulic fluid to flow from this line to one or more cylinders 150 if the pressure in the supply line reaches a predetermined threshold.

[0053] Sensors such as the pressure sensor PS and the position sensors 211, 231 may be arranged to detect a fault or failure associated with the supply of hydraulic fluid to one or more cylinders 150. Such sensors may be coupled to electronics, such as a control circuit, controller, or processor, to determine a fault or failure condition of the system 200, 300. For example, a low pressure reading from one of the pressure sensors PS may be processed by the electronics to identify a fault or failure associated with the primary power source E and / or the first pump 210 or the auxiliary power source M and / or the second pump 230, based on the position of the sensor.

[0054] Detecting a fault or failure using a sensor can be used to alert an operator of the machine 100 to the fault or failure and control the flow of hydraulic fluid to one or more cylinders 150 by selectively closing the selector valve of the first selector valve device 220 or the second selector valve device 240, depending on whether Figure 2 System 200 or Figure 3 The system 300 is shown. Closing the selector valve of the first selector valve device 220 or the second selector valve device 240 can block the hydraulic fluid from the first pump 210 or the second pump 230. Therefore, when a fault or failure is detected, a control signal can be provided to the control valve device 290, 390 for actuation, which can cause hydraulic fluid to flow from the pressurized circuit 250, 350 to the control input of the first selector valve device 220 and / or the second selector valve device 240 to block the hydraulic fluid from the first pump 210 or the second pump 230 from reaching one or more cylinders 150.

[0055] Alternatively, the system 200 may periodically send a control signal to the control valve arrangement 290 to switch between which of the first pump 210 or the second pump 230 provides hydraulic fluid to the one or more cylinders 150, even if no fault is detected in the system 200, as a means of testing the redundant operability of providing hydraulic fluid from the second pump 230 to the one or more cylinders 150. After performing the redundancy test, the system 200 may switch back to having the first pump 210 provide hydraulic fluid to the one or more cylinders 150. The system 300 may similarly periodically shut off the primary supply from one of the first pump 210 or the second pump 230 for testing purposes.

[0056] While aspects of the present disclosure have been particularly shown and described with reference to the above embodiments, it will be understood by those skilled in the art that various additional embodiments may be contemplated by modifying the disclosed machines, systems, and methods without departing from the spirit and scope of the disclosure. Such embodiments are to be understood as falling within the scope of the present disclosure as determined by the claims and any equivalents thereof.

Claims

1. A wheeled machine (100), comprising: a pair of steering cylinders (150) configured to control steering motion associated with the wheeled machine (100); a main power source (E) of the wheeled machine (100); Auxiliary power source (M); a first variable displacement pump (210) operatively coupled to the primary power source (E) and configured to output a primary supply of hydraulic fluid to the pair of steering cylinders (150) based on operation of the primary power source (E); a second variable displacement pump (230) operatively coupled to the auxiliary power source (M) and configured to output an auxiliary supply of hydraulic fluid to the pair of steering cylinders (150) based on operation of the auxiliary power source (M); a first pair of selector valves (220) coupled to the first variable displacement pump (210); a second pair of selector valves (240) coupled to the second variable displacement pump (230); and a pressurizing circuit (250) coupled to respective control inputs of the first pair of selector valves (220) and the second pair of selector valves (240) and configured to selectively supply hydraulic fluid to the control inputs of the first pair of selector valves (220) and the second pair of selector valves (240) to prevent hydraulic fluid from only one of the first variable displacement pump (210) and the second variable displacement pump (230) from being supplied to the pair of steering cylinders (150) and to provide hydraulic fluid from only one of the other of the first variable displacement pump (210) and the second variable displacement pump (230) to the pair of steering cylinders (150), wherein the primary hydraulic fluid supply and the auxiliary hydraulic fluid supply to the pair of steering cylinders (150) are unmetered, The pressurizing circuit (250) comprises: A main pressurizing sub-circuit (260) having a first pressurizing pump (262), an auxiliary pressurizing sub-circuit (270) having a second pressurizing pump (272), and A control valve device (290, 390) is coupled to the control inputs of the first pair of selector valves (220) and the second pair of selector valves (240), and is selectively coupled to the respective outputs of the main pressurizing sub-circuit (260) and the auxiliary pressurizing sub-circuit (270) via a dedicated valve (280) between the main pressurizing sub-circuit (260) and the auxiliary pressurizing sub-circuit (270).

2. The wheeled machine (100) of claim 1, wherein the pressurizing circuit (250) is operable to supply hydraulic fluid to control inputs of the first pair of selector valves (220) to close the first pair of selector valves (220) in response to a control signal provided to the control valve arrangement (290, 390) of the pressurizing circuit, thereby preventing hydraulic fluid from the first variable displacement pump (210) from being provided to the pair of steering cylinders (150), the control signal being generated when one or more sensors (211, 231) detects a fault associated with the primary power source (E) and / or the first variable displacement pump (210).

3. The wheeled machine (100) of claim 2, wherein the pressurizing circuit (250) is operable to supply hydraulic fluid to the control inputs of the second pair of selector valves (240) in response to a control signal provided to the control valve arrangement (290) to open the second pair of selector valves (240) to begin providing hydraulic fluid from the second variable displacement pump (230) to the pair of steering cylinders (150).

4. The wheeled machine (100) of claim 3, wherein the control valve arrangement (290) has only one control valve having an output coupled to control inputs of the first and second pair of selector valves (220, 240).

5. The wheeled machine (100) of claim 2, wherein the pressurized circuit (250) is operable to maintain the second pair of selector valves (240) open to continue providing hydraulic fluid from the second variable displacement pump (230) to the pair of steering cylinders (150).

6. The wheeled machine (100) of claim 2, wherein the control valve arrangement (390) has two control valves (392, 394), a first control valve (392) coupled to a control input of the first pair of selector valves (220) and a second control valve (394) coupled to a control input of the second pair of selector valves (240).

7. The wheeled machine (100) of claim 2, wherein the pressurizing circuit (250) is operable to supply hydraulic fluid to the control inputs of the second pair of selector valves (240) to close the second pair of selector valves (240) in response to a control signal provided to the control valve arrangement (290, 390), thereby preventing hydraulic fluid from the second variable displacement pump (230) from being provided to the pair of steering cylinders (150), the control signal being generated when one or more sensors (211, 231) detects a fault associated with the auxiliary power source (M) and / or the second variable displacement pump (230).

8. The wheeled machine (100) of claim 2, wherein the auxiliary power source (M) is an electric motor or a ground-driven power source driven by movement of a drive shaft of the wheeled machine (100).

9. The wheeled machine (100) of claim 1, wherein the primary power source (E) is an engine.

10. The wheeled machine (100) of claim 1, wherein the primary power source (E) is separate from the auxiliary power source (M).

11. A redundant steering method, comprising: Provides the main power source (E); Providing auxiliary power source (M); providing a first variable displacement pump (210) operatively coupled to the primary power source (E) and configured to output a first supply of hydraulic fluid to at least one steering cylinder (150) based on operation of the primary power source (E); providing a second variable displacement pump (230) operably coupled to the auxiliary power source (M) and configured to output a second supply of hydraulic fluid to the at least one steering cylinder (150) based on operation of the auxiliary power source (M); providing a first selector valve arrangement (220) coupled to the first variable displacement pump (210) and the second variable displacement pump (230); providing a second selector valve arrangement (240) coupled to the first variable displacement pump (210) and the second variable displacement pump (230); and providing a pressurizing circuit (250) coupled to respective control inputs of the first selector valve device (220) and the second selector valve device (240) and configured to selectively supply hydraulic fluid to the control inputs of the first selector valve device (220) and the second selector valve device (240) based on detection of a fault associated with the primary power source (E) and / or the first variable displacement pump (210) or the auxiliary power source (M) and / or the second variable displacement pump (230) to prevent hydraulic fluid from only one of the first variable displacement pump (210) and the second variable displacement pump (230) from being supplied to the at least one steering cylinder (150) and thereby supply hydraulic fluid from only one of the other of the first variable displacement pump (210) and the second variable displacement pump (230) to the at least one steering cylinder (150), The pressurizing circuit (250) comprises: A main pressurizing sub-circuit (260) having a first pressurizing pump (262), an auxiliary pressurizing sub-circuit (270) having a second pressurizing pump (272), and A control valve device (290, 390) is coupled to the control inputs of the first selector valve device (220) and the second selector valve device (240), and is selectively coupled to the respective outputs of the main pressurizing sub-circuit (260) and the auxiliary pressurizing sub-circuit (270) via a dedicated valve (280) between the main pressurizing sub-circuit (260) and the auxiliary pressurizing sub-circuit (270).

12. The redundant steering method according to claim 11 further includes preventing hydraulic fluid from said only one of the first variable displacement pump (210) and the second variable displacement pump (230) from being supplied to said at least one steering cylinder (150) and providing hydraulic fluid from said only one of the other of the first variable displacement pump (210) and the second variable displacement pump (230) to said at least one steering cylinder (150) based on detection of a fault associated with the primary power source (E) and / or the first variable displacement pump (210) or the auxiliary power source (M) and / or the second variable displacement pump (230).

13. The redundant steering method according to claim 12, wherein from a state in which the second variable displacement pump (230) does not supply hydraulic fluid to the at least one steering cylinder (150) to a state in which the second variable displacement pump (230) supplies hydraulic fluid to the at least one steering cylinder (150), blocking the hydraulic fluid from being supplied to the at least one steering cylinder (150) is for the first variable displacement pump (210), and supplying the hydraulic fluid to the at least one steering cylinder is for the second variable displacement pump (230).

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