WO2023002457A1

WO2023002457A1 - Fail-operational steer-by-wire hydraulic valve

Info

Publication number: WO2023002457A1
Application number: PCT/IB2022/056816
Authority: WO
Inventors: Michael William Olson; Amol Shripal KUMBHAR
Original assignee: Danfoss Power Solutions Ii Technology A/S; Eaton Intelligent Power Limited
Priority date: 2021-07-23
Filing date: 2022-07-22
Publication date: 2023-01-26

Abstract

A steer-by-wire hydraulic valve (100) is designed with redundant left and right halves (120L, 120R) with each half (120L, 120R) including solenoid-operated flow-metering (11, 15), flow direction (18, 21) and isolation valves (18, 21). During normal operation, the left half (120L) provides a left steering function by providing a steering flow from the left flow-metering valve (11) proportional to a left steering command. During normal operation, the right half (120R) provides a right steering function by providing a steering flow from the right flow-metering valve (15) proportional to a right steering command. However, if a fault is detected in one of the halves (120L, 120R), the half with the fault operates to de-activate all solenoid valves (10, 17; 14, 20) within the respective half (120L, 120R). The valve half without the fault assumes responsibility for executing both right and left steering commands by using its respective flow-metering valve (11; 15) and flow direction valve (18, 21) to provide the desired left or right steering direction.

Description

FAIL-OPERATIONAL STEER-BY-WIRE HYDRAULIC VALVE

Cross-Reference to Related Application

[0001] This application is being filed on July 22, 2022, as a PCT International Patent application and claims the benefit of and priority to Indian Provisional Patent Application No. 202111033118, filed July 23, 2021, the entire disclosure of which is incorporated by reference herein in its entirety.

Technical Field

[0002] The present disclosure is directed to hydraulic valves and, more particularly, to a hydraulic valve that can provide fail-operational steering service in a vehicle steer-by-wire hydraulic system.

Background

[0003] A vehicle configured with steer-by-wire operation has had the mechanical linkage between the driver’s steering wheel and the vehicle’s wheels removed. Instead of a mechanical linkage, a driver’s intent for left or right steering is translated into one more control signals by a controller that directs the operation of various motors, pumps, valves, sensors, actuators, etc. within the vehicle to achieve the desired steering operation.

Summary

[0004] A steer-by-wire hydraulic valve is designed with redundant left and right halves with each half including solenoid-operated flow-metering, flow direction, and isolation valves. During normal operation, the left half provides a left steering function by providing a steering flow from the left flow-metering valve proportional to a left steering command. During normal operation, the right half provides a right steering function by providing a steering flow from the right flow-metering valve proportional to a right steering command. However, if a fault is detected in one of the halves, the half with the fault operates to de-activate all solenoid valves within the respective half providing a redundant means to isolate hydraulic flow and prevent unintended or incorrect steering flow. The valve half without the fault, e.g., the fault-free half, assumes responsibility for executing both right and left steering commands by using its respective flow-metering valve to deliver a steering flow proportional to a left or right steering command and by using its respective flow direction valve to provide the desired left or right steering direction.

[0005] In certain aspects, the present disclosure is directed to a steer-by-wire hydraulic valve having a housing that includes a left steering circuit and a right steering circuit. Each of the left and right steering circuits, respectively, has valving to perform a flow-metering function, an isolation function, and a flow direction function with the flow-metering, isolation, and flow direction functions controlled by a solenoid valve. The left steering circuit provides left steering flow during normal operation and provides both left and right steering flow during fault operation caused by a fault in the right steering circuit. The right steering circuit provides right steering flow during normal operation and provides left and right steering flow during fault operation caused by a fault in the left steering circuit.

[0006] In certain aspects, the present disclosure is directed to a steer-by-wire hydraulic valve having a housing that includes a left steering circuit and a right steering circuit. When operating under a normal mode of operation, the left steering circuit provides a steering flow proportional to a left steering command to actuate a left steering cylinder and the right steering circuit provides a steering flow proportional to a right steering command to actuate a right steering cylinder. When operating under a fault mode of operation, presuming a fault has occurred in either the left steering circuit or the right steering circuit, the fault-free left or right steering circuit provides both left and right steering flows proportional to a respective left or right steering command to actuate a respective left or right steering cylinder.

[0007] In certain aspects, the present disclosure is directed to a steer-by-wire hydraulic valve that includes a housing having a left steering circuit having a solenoid- controlled flow-metering valve and a solenoid-controlled isolation and flow direction valve as well as a right steering circuit, which is identical to the left steering circuit, having a solenoid-controlled flow-metering valve and a solenoid-controlled isolation and flow direction valve. The housing further includes a load sense valve in hydraulic communication with both the left and right steering circuits. The left steering circuit provides a left steering flow during normal operation and provides both a left steering flow and a right steering flow during fault operation caused by a fault in the right steering circuit. Similarly, the right steering circuit provides a right steering flow during normal operation and provides both a left steering flow and a right steering flow during fault operation caused by a fault in the left steering circuit.

[0008] A variety of additional inventive aspects will be set forth in the description that follows. The inventive aspects can relate to individual features and to combinations of features. It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad inventive concepts upon which the embodiments disclosed herein are based.

Brief Description of the Drawings

[0009] FIG. 1 is hydraulic diagram of a fail-operational steer-by-wire hydraulic valve according to the present disclosure.

[0010] FIG. 2 is a hydraulic diagram illustrating a stand-by normal steering operation of a steer-by-wire hydraulic system.

[0011] FIG. 3 is a hydraulic diagram illustrating a left steering normal operation of the steer-by-wire hydraulic system.

[0012] FIG. 4 is a hydraulic diagram illustrating a right steering normal operation of the steer-by-wire hydraulic system.

[0013] FIG. 5 is a hydraulic diagram illustrating a left steering fault operation of the steer-by-wire hydraulic system.

[0014] FIG. 6 is a hydraulic diagram illustrating a right steering fault operation of the steer-by-wire hydraulic system.

[0015] FIG. 7 is hydraulic diagram of an alternative embodiment of a fail- operational steer-by-wire hydraulic valve according to the present disclosure.

[0016] FIG. 8 is a hydraulic diagram illustrating a left steering normal operation of the steer-by-wire hydraulic system operating in conjunction with an Ackerman-style steering configuration.

Detailed Description

[0017] A steer-by-wire hydraulic valve is designed with redundant left and right halves with each half including solenoid-operated flow-metering, flow direction, and isolation valves. During normal operation, the left half provides a left steering function by providing a steering flow from the left flow-metering valve proportional to a left steering command. During normal operation, the right half provides a right steering function by providing a steering flow from the right flow-metering valve proportional to a right steering command. However, if a fault is detected in one of the halves, the half with the fault operates to de-activate all solenoid valves within the respective half providing a redundant means to isolate hydraulic flow and prevent unintended or incorrect steering flow. The valve half without the fault, e.g., the fault-free half, assumes responsibility for executing both right and left steering commands by using its respective flow-metering valve to deliver a steering flow proportional to a left or right steering command and by using its respective flow direction valve to provide the desired left or right steering direction.

[0018] Referring to FIG. 1, a fail-operational steer-by-wire hydraulic valve 100 according to the present disclosure is illustrated. The hydraulic valve 100 includes a valve housing 110 having a first inlet port PI that provides a connection point for a high pressure primary pump hydraulic supply hose, a drain port D that provides a connection point for a low pressure pilot control drain hose, and a tank port T that provides a connection point for return steering flow to a hydraulic reservoir. The valve housing 110 additionally includes an inlet gauge port P-G for measuring inlet pressure, a load sense port LS providing a connection point for a load sense signal coming from the valve 100, a load sense gauge port LS-G for measuring a load sense pressure, as well as a second inlet port P2 providing a connection point for a backup pump hydraulic supply hose.

[0019] External to the valve housing 110, a first inlet pressure sensor 1 provides measurement of inlet steering pressure, while a load sense pressure sensor 2 provides measurement of a load sense pressure. Within the valve housing 110, a first inlet check valve 3 prevents hydraulic pressure from back flowing into a primary hydraulic pump circuit when a backup pump is active and a load sense relief valve 4 limits a maximum load sense signal, which also results in limiting maximum inlet pressure. Further included within the valve housing 110 is a second inlet check valve 5 that prevents hydraulic pressure from back flowing into a backup hydraulic pump circuit when the primary hydraulic pump is active.

[0020] The valve housing 110 additionally includes a left steering circuit 120L and an identical right steering circuit 120R. The left steering circuit 120L includes an inlet screen 6 to prevent contaminants from reaching the left pilot control valves 10 and 17, and a pressure reducing valve 7 that reduces the inlet pressure to a pilot control pressure suitable for left pilot control valves 10 and 17. Similarly, the right steering circuit 120R includes an inlet screen 8 to prevent contaminants from reaching the right pilot control valves 14 and 20, and a pressure reducing valve 9 that reduces the inlet pressure to a pilot control pressure suitable for right pilot control valves 14 and 20.

[0021] Further, within the left steering circuit 120L, is a two-position solenoid left steering pilot valve 10 that meters a control pressure into cavities of a left flow metering spool valve 11. The left flow-metering spool valve 11 meters pressure/flow from its pressure port to the left flow direction and isolation pilot valve 17; a left spool valve position sensor 12 provides position feedback to a controller (not shown). The left flow direction and isolation pilot valve 17 is a three-position solenoid valve that meters a control pressure into the cavities of a flow direction and isolation spool valve 18. The left flow direction and isolation spool valve 18 is a three-position valve that directs pressure/flow from the left flow-metering spool valve 11 to left (L) or right (R) ports; the left flow direction and isolation spool valve 18 isolates flow in the neutral position. A left flow direction and isolation spool valve position sensor 19 provides position feedback of the left flow direction and isolation spool valve 18. The left flow direction and isolation spool valve 18 is in communication with both a right steering port R and a left steering port L of the valve housing 110.

[0022] Similarly, within the right steering circuit 120R, is a two-position solenoid right steering pilot valve 14 that meters a control pressure into pilot cavities of a right flow-metering spool valve 15. The right flow-metering spool valve 15 meters pressure/flow from its pressure port to a right flow direction and isolation pilot valve 20; a right spool valve position sensor 16 provides position feedback to a controller (not shown). The right flow direction and isolation pilot valve 20 is a three-position solenoid valve that meters a control pressure into the pilot cavities of the right flow direction and isolation spool valve 21. The flow direction and isolation spool valve 21 is a three- position valve that directs valve pressure/flow from the right flow-metering spool valve 15 to the left (L) or right (R) ports; the right flow direction and isolation spool valve 21 isolates flow in the neutral position. A right flow direction and isolation spool valve position sensor switch 22 provides position feedback of the right flow direction and isolation spool valve 21. The right flow direction and isolation spool valve 21 is in communication with the right steering port R and the left steering port L of the valve housing 110.

[0023] Separate from the left steering circuit 120L and the right steering circuit 120R is a left steering port L that provides the connection point for a left steering hose that is coupled to a left steering cylinder (see FIGS. 2-6) and a right steering port R that provides the connection point for a right steering hose that is coupled to a right steering cylinder (see FIGS. 2-6). A left steering gauge port L-G is also provided in the valve housing 110 and is coupled to an external left steering port sensor 25 that provides measurement of the left steering port pressure. Similarly, a right steering gauge port R- G is also provided in the valve housing 110 and is coupled to an external right steering port sensor 24 that provides measurement of the right steering port pressure. Notably, both the left steering circuit 120L and the right steering circuit 120R can access both the left port L and the right port R.

[0024] A load sense shuttle valve 13 communicates the maximum load sense pressure provided by the left flow-metering spool valve 11 and the right flow-metering spool valve 15 and is in communication with the load sense port LS. Cylinder relief and anti-cavitation valves 23 (e.g., one in hydraulic communication with the left port L and one in hydraulic communication with the right port R) prevent high pressure events from reaching the steering valve components and prevent cavitation in the steering cylinders (see FIGS. 2-6).

[0025] Referring now to FIGS. 2-6, example implementations of the fail- operational steer-by-wire hydraulic valve 100 are illustrated. Each example implementation includes a vehicle steer-by-wire hydraulic system 200 having a primary steering pump 202, a back-up pump 204, a hydraulic reservoir 206, as well as a left steering cylinder 210(L) and a right steering cylinder 210(R). The example implementations of FIGS. 2-6 illustrate articulated steering; however, the fail- operational steer-by-wire hydraulic valve 100 can be similarly implemented in Ackerman steering systems as shown in FIG. 8.

[0026] FIG. 2 illustrates the hydraulic flow within the fail-operational steer-by wire hydraulic valve 100 when the steer-by-wire hydraulic system 200 is under normal operation and executing a stand-by (e.g., no steering) command. As shown, the hydraulic pressure and flow is generated from the primary pump 202 and enters the valve housing 110 through the check valve 3. The primary pump 202 is a load sense pump and generates enough flow to maintain a stand-by pressure setting. Left pressure reducing valve 7 and right pressure reducing valve 9 reduce the primary pump pressure to a level usable by both the left steering pilot valve 10 and left flow direction and isolation pilot valve 17 and by both the right steering pilot valve 14 and right flow direction and isolation pilot valve 20. The correct solenoid on the left flow direction and isolation pilot valve 17 is energized to move the left flow direction and isolation spool valve 18 to a non-isolating position that directs the proportional flow from the left flow-metering spool valve 11 to the left steering port L. The correct solenoid on the right flow direction and isolation pilot valve 20 is energized to move the right flow direction and isolation spool valve 21 to a non-isolating position that directs the proportional flow from the right flow-metering spool valve 15 to the right steering port R. In the stand-by condition, the left steering pilot valve 10 and the right steering pilot valve 14 are de-energized. As a consequence, the left flow-metering spool valve 11 and the right flow-metering spool valve 15 block hydraulic flow to the left and right steering cylinders 210(L), 210(R).

[0027] FIG. 3 illustrates the hydraulic flow within the fail-operational steer-by wire hydraulic valve 100 when the steer-by-wire hydraulic system 200 is under normal operation and executing a left steering command. As shown, hydraulic pressure and flow is generated from the primary pump 202 and enters the fail-operational steer-by wire hydraulic valve 100 through the first inlet check valve 3. The primary pump 202 is a load sense pump and generates enough flow to maintain the stand-by pressure setting. Left pressure reducing valve 7 and right pressure reducing valve 9 reduce the primary pump pressure to a level usable by both the left steering pilot valve 10 and left flow direction and isolation pilot valve 17 and by both the right steering pilot valve 14 and right flow direction and isolation pilot valve 20. The correct solenoid on the left flow direction and isolation pilot valve 17 is energized to move the left flow direction and isolation spool valve 18 to a non-isolating position that directs the proportional flow from the left flow-metering spool valve 11 to the left steering port L. The correct solenoid on the right flow direction and isolation pilot valve 20 is energized to move valve 21 to a non-isolating position that directs the proportional flow from the right flow-metering spool valve 15 to the right steering port R.

[0028] In a left steering flow condition, the left steering pilot valve 10 is commanded proportionally to achieve the desired steering flow through the left flow metering spool valve 11. Hydraulic fluid provided by the primary pump 202 is metered through the left flow-metering spool valve 11. A steering load sense signal is picked up in the left flow direction and isolation spool valve 18 and is communicated back to the primary pump 202 through the left flow-metering spool valve 11 and the load sense shuttle valve 13. The primary pump 202 load sense displacement control manages the pump flow output to achieve the desired margin pressure and, as a result, provides the required steering flow. The steering flow leaves the left flow direction and isolation spool valve 18 and enters both a base of the right side steering cylinder 210(R) and the rod end of the left side steering cylinder 210(L) resulting in the vehicle turning left.

[0029] FIG. 4 illustrates the hydraulic flow within the fail-operational steer-by wire hydraulic valve 100 when the steer-by-wire hydraulic system 200 is under normal operation and executing a right steering command. As shown, hydraulic pressure and flow is generated from the primary pump 202 and enters the fail-operational steer-by wire hydraulic valve 100 through the first inlet check valve 3. The primary pump 202 is a load sense pump and generates enough flow to maintain the stand-by pressure setting. Left pressure reducing valve 7 and right pressure reducing valve 9 reduce the primary pump pressure to a level usable by both the left steering pilot valve 10 and left flow direction and isolation pilot valve 17 and by both the right steering pilot valve 14 and right flow direction and isolation pilot valve 20. The correct solenoid on the right flow direction and isolation pilot valve 20 is energized to move the right flow direction and isolation spool valve 21 to a non-isolating position that directs the proportional flow from the right flow-metering spool valve 15 to the right steering port R. The correct solenoid on the left flow direction and isolation pilot valve 17 is energized to move left flow direction and isolation spool valve 18 to a non-isolating position that directs the proportional flow from the left flow-metering spool valve 11 to the left steering port L.

[0030] In a right steering flow condition, the right steering pilot valve 14 is commanded proportionally to achieve the desired steering flow through the right flow metering spool valve 15. Hydraulic fluid provided by the primary pump 202 is metered through the right flow-metering spool valve 15. A steering load sense signal is picked up in the right flow direction and isolation spool valve 21 and communicated back to the primary pump 202 through the right flow-metering spool valve 15 and the load sense shuttle valve 13. The primary pump 202 displacement control manages the pump flow output to achieve the desired margin pressure and, as a result, provides the required steering flow. The steering flow leaves the right flow direction and isolation spool valve 21 and enters both the base of the left side steering cylinder 210(L) and the rod end of the right side steering cylinder 210(R) resulting in the vehicle turning right.

[0031] FIG. 5 illustrates the hydraulic flow within the fail-operational steer-by wire hydraulic valve 100 when the steer-by-wire hydraulic system 200 is under fault operation and executing a left steering command. In the illustrated fault scenario, there is a component fault detected by a sensor that disables the right half (e.g., the right steering circuit 120R, see FIG. 1) of the fail-operational steer-by-wire hydraulic valve 100. In this scenario, an issue with any electrical, electronic, or hydraulic component involved with items 8, 9, 14, 15, 16, 20, 21, or 22 has resulted in a steering controller (not shown) switching to a fault mode of operation. This description of operation would be similar and repeated on the right side of the fail-operational steer-by-wire hydraulic valve 100 if a component with the left half (e.g., the left steering circuit 120L, see FIG. 1) of the fail-operational steer-by-wire hydraulic valve 100 was detected.

[0032] As shown in FIG. 5, hydraulic pressure and flow is generated by the primary pump 202 and enters the fail-operational steer-by-wire hydraulic valve 100 through the first inlet check valve 3. The primary pump 202 is a load sense pump that generates enough flow to maintain the stand-by pressure setting. Left pressure reducing valve 7 and right pressure reducing valve 9 reduce the primary pump pressure to a level usable by both the left steering pilot valve 10 and left flow direction and isolation pilot valve 17 and by both the right steering pilot valve 14 and right flow direction and isolation pilot valve 20. The correct solenoid on the left flow direction and isolation pilot valve 17 is energized to move left flow direction and isolation spool valve 18 to a non-isolating position that directs the proportional flow from the left flow-metering spool valve 11 to the left steering port L. All solenoids on the right steering pilot valve 14 and the right flow direction and isolation pilot valve 20 are de-energized, which results in a redundant means for isolating hydraulic steering flow from the right half of the fail-operational steer-by-wire hydraulic valve 100.

[0033] In a left steering flow condition, the left steering pilot valve 10 is commanded proportionally to achieve the desired steering flow through the left flow metering spool valve 11. Hydraulic fluid provided by the primary pump 202 is metered through the left flow-metering spool valve 11. The steering load sense signal is picked up in the left flow direction and isolation spool valve and communicated back to the primary steering pump 202 through the left flow-metering spool valve 11 and the load sense shuttle valve 13. The primary steering pump displacement control manages pump flow output to achieve a desired margin pressure and as a result provides the required steering flow. The steering flow leaves the fail-operational steer-by-wire hydraulic valve 100 through the left steering port L and enters the base of the right side steering cylinder 210(R) and the rod end of the left side steering cylinder 210(L), which results in the vehicle turning left.

[0034] FIG. 6 illustrates the hydraulic flow within the fail-operational steer-by wire hydraulic valve 100 when the steer-by-wire hydraulic system 200 is under fault operation and executing a right steering command. In the illustrated fault scenario, there is a component fault detected by the sensor that disables the right half (e.g., the right steering circuit 120R, see FIG. 1) of the fail-operational steer-by-wire hydraulic valve 100. In this scenario an issue with any electrical, electronic, or hydraulic component involved with items 8, 9, 14, 15, 16, 20, 21, or 22 has resulted in a steering controller (not shown) switching to a fault mode of operation. This description of operation would be similar and repeated on the right side of the fail-operational steer- by-wire hydraulic valve 100 if a component with the left half (e.g., the left steering circuit 120L, see FIG. 1) of the fail-operational steer-by-wire hydraulic valve 100 was detected.

[0035] As shown in FIG. 6, hydraulic pressure and flow is generated by the primary pump 202 and enters the fail-operational steer-by-wire hydraulic valve 100 through the first inlet check valve 3. The primary pump 202 is a load sense pump that generates enough flow to maintain the stand-by pressure setting. Left pressure reducing valve 7 and right pressure reducing valve 9 reduce the primary pump pressure to a level usable by both the left steering pilot valve 10 and left flow direction and isolation pilot valve 17 and by both the right steering pilot valve 14 and right flow direction and isolation pilot valve 20. The correct solenoid on the left flow direction and isolation pilot valve 17 is energized to move left flow direction and isolation spool valve 18 to a non-isolating position that directs the proportional flow from the left flow-metering spool valve 11 to the right steering port R. All solenoids on the right steering pilot valve 14 and the right flow direction and isolation pilot valve 20 are de-energized, which results in a redundant means for isolating hydraulic steering flow from the right half of the fail-operational steer-by-wire hydraulic valve 100.

[0036] In a right steering flow condition, the left steering pilot valve 10 is commanded proportionally to achieve the desired steering flow through the left flow metering spool valve 11. Hydraulic fluid provided by the primary pump 202 is metered through the left flow-metering spool valve 11. The steering load sense signal is picked up in the left flow direction and isolation spool valve 18 and communicated back to the primary steering pump 202 through the left flow-metering spool valve 11 and the load sense shuttle valve 13. The primary steering pump displacement control manages pump flow output to achieve a desired margin pressure and as a result provides the required steering flow. The steering flow leaves the fail-operational steer-by-wire hydraulic valve 100 through the right steering port R and enters the base of the left side steering cylinder 210(L) and the rod end of the right steering cylinder 210(R), which results in the vehicle turning right.

[0037] FIG. 7 illustrates an alternative configuration of the fail-operational steer- by-wire hydraulic valve 100. The illustrated fail-operational steer-by-wire hydraulic valve 700 includes a valve housing 710 having a first inlet port PI that provides a connection point for a high-pressure primary pump hydraulic supply hose, a drain port D that provides a connection point for a low pressure pilot control drain hose, and a tank port T that provides a connection point for return steering flow to a hydraulic reservoir. The valve housing 710 additionally includes an inlet gauge port P-G for measuring inlet pressure, a load sense port LS providing a connection point for a load sense signal coming from the valve 700, a load sense gauge port LS-G for measuring a load sense pressure as well as a second inlet port P2 providing a connection point for a backup pump hydraulic supply hose. [0038] External to the valve housing 710, a first inlet pressure sensor 7-1 provides measurement of inlet steering pressure while a load sense pressure sensor 7-2 provides measurement of a load sense pressure. Within the valve housing 710, a first inlet check valve 7-3 prevents hydraulic pressure from back flowing into a primary hydraulic pump circuit when a backup pump is active and a load sense relief valve 7-4 limits a maximum load sense signal, which also results in limiting maximum inlet pressure. Further included within the valve housing 710 is a second inlet check valve 7-5 that prevent hydraulic pressure from back flowing into a backup hydraulic pump circuit when the primary hydraulic pump is active.

[0039] The valve housing 710 additionally includes a left steering circuit 720L and a right steering circuit 720R. The left steering circuit 720L includes an inlet screen 7-6 to prevent contaminants from reaching the left pilot control valves 7-10, 7-17, and 7-23, and a pressure reducing valve 7-7 that reduces the inlet pressure to a pilot control pressure suitable for left pilot control valves 7-10, 7-17, and 7-23. Similarly, the right steering circuit 720R includes an inlet screen 7-8 to prevent contaminants from reaching the right pilot control valves 7-14, 7-20, 7-27 and a pressure reducing valve 7- 9 that reduces the inlet pressure to a pilot control pressure suitable for right pilot control valves 7-14, 7-20, and 7-26.

[0040] Further, within the left steering circuit 720L, is a two-position solenoid left isolation pilot valve 7-10 that meters a control pressure into pilot cavities of a left isolation spool valve 7-11. The left isolation valve 7-11 allows or prevents hydraulic oil from entering a left flow-metering valve 7-18. The left steering pilot valve 7-17 meters a control pressure into pilot cavities of the left flow-metering spool valve 7-18. The left flow-metering spool valve 7-18 meters pressure/flow from its pressure port to a left flow direction valve 7-24, and a left flow direction spool valve sensor 7-25 provides position feedback of the left flow direction spool valve 7-24 to the controller. The left flow direction pilot valve 7-23 meters a control pressure into the pilot cavities of the left flow direction spool valve 7-24. The left flow direction spool valve 7-24 directs steering pressure/flow to either the left port L or right port R, and the left flow direction spool valve sensor 7-25 provides position feedback of the left flow direction spool valve 7-24 to the controller. A left steering gauge port L-G is also provided in the valve housing 710 and is coupled to an external left steering port sensor 7-31 that provides measurement of the left steering port pressure.

[0041] Similarly, within the right steering circuit 720R, is a two-position solenoid right isolation pilot valve 7-14 that meters a control pressure into pilot cavities of a right isolation spool valve 7-15. The right isolation valve 7-15 allows or prevents hydraulic oil from entering a right flow-metering valve 7-21. The right steering pilot valve 7-20 meters a control pressure into pilot cavities of the right flow-metering spool valve 7-21. The right flow-metering spool valve 7-21 meters pressure/flow from its pressure port to the right flow direction valve 7-27, and a right flow direction spool valve sensor 7-28 provides position feedback of the right flow direction spool valve 7- 27 to the controller. The right flow direction pilot valve 7-26 meters a control pressure into pilot cavities of the right flow direction spool valve 7-27. The right flow direction spool valve 7-27 directs steering pressure/flow to either the left port L or right port R, and the right flow direction spool valve sensor 7-28 provides position feedback of the right flow direction spool valve 7-27 to the controller. A right steering gauge port R-G is also provided in the valve housing 710 and is coupled to an external right steering port sensor 7-30 that provides measurement of the right steering port pressure.

[0042] Additional sensors within the left and right steering circuits 720L, 720R include a left steering isolation valve position sensor 7-12, a right steering circuit isolation valve position sensor 7-16, a left steering circuit flow metering valve position sensor 7-19, and a right steering circuit flow-metering valve position sensor 7-22.

[0043] A load sense shuttle valve 7-13 communicates the maximum load sense pressure provided by the left isolation spool valve 7-11 and right isolation spool valve 7-15 and is in communication with the load sense port LS. Relief and anti-cavitation valves 7-29 prevent high pressure events from reaching the steering valve components and prevent cavitation in the steering cylinders (see FIGS. 2-6).

[0044] The fail-operational steer-by-wire hydraulic valve 700 functionally operates the same as fail-operational steer-by-wire hydraulic valve 100 with the left isolation pilot valve 7-10, left isolation spool valve-7-11, left flow direction pilot valve 7-23, and left flow direction spool valve 7-24 replicating the valving functionality of the left flow direction and isolation pilot valve 17 and left flow direction and isolation spool valve 18. Similarly, the right isolation pilot valve 7-14, right isolation spool valve-7-15, right flow direction pilot valve 7-26, and right flow direction spool valve 7-27 replicate the valving functionality of the right flow direction and isolation pilot valve 20 and right flow direction and isolation spool valve 21. Other valving configurations to execute the functionality of the fail-operational steer-by-wire hydraulic valves 100, 700 are also possible.

[0045] Each of the fail-operational steer-by-wire hydraulic valves 100, 700 achieves a PLe (i.e., Performance Level e) and SIL3 (i.e., Safety Integrity Level 3) for the following steer-by-wire safety functions of: (a) preventing unrequested steering flow; (b) preventing loss of steering flow; and (c) preventing steering flow in the wrong direction. The architecture of the fail-operational steer-by-wire hydraulic valve and the noted safety performance enable an OEM (i.e., Original Equipment Manufacturer) to certify their steer-by-wire steering systems to the IEC (i.e., International Electrotechnical Commission) 61508 standard and the ISO (i.e., International Organizations for Standardization) 13849 standard at competitive cost and package size.

[0046] FIG. 8 illustrates the hydraulic flow within the fail-operational steer-by wire hydraulic valve 100 when the steer-by-wire hydraulic system 200 is under normal operation and executing a left steering command to control an Ackerman-style steering configuration that includes a steering actuator 810 having left and right ports that control respective left and right tie rods; the tie rods being secured to left and right wheels, respectively.

[0047] This disclosure describes some aspects of the present technology with reference to the accompanying drawings, in which only some of the possible aspects were shown. Other aspects can, however, be embodied in many different forms and should not be construed as limited to the aspects set forth herein. Rather, these aspects were provided so that this disclosure is thorough and complete and fully conveys the scope of the possible aspects to those skilled in the art.

[0048] As should be appreciated, the various aspects described with respect to the figures herein are not intended to limit the technology to only those aspects described. Accordingly, additional configurations can be used to practice the technology herein and/or some aspects described can be excluded without departing from the methods and systems disclosed herein.

[0049] Similarly, where operations of a process are disclosed, those operations are described for purposes of illustrating the present technology and are not intended to limit the disclosure to a particular sequence of operations. For example, the operations can be performed in differing order, two or more operations can be performed concurrently, additional operations can be performed, and disclosed operations can be excluded without departing from the present disclosure. Further, each operation can be accomplished via one or more sub-operations. The disclosed processes can be repeated.

Claims

What is Claimed:

1. A steer-by-wire hydraulic valve comprising: a valve housing including: a left steering circuit having valving to perform a flow-metering function, an isolation function, and a flow direction function, the flow-metering, isolation, and flow direction functions being controlled by a solenoid valve; and a right steering circuit having valving to perform a flow-metering function, an isolation function, and a flow direction function, the flow-metering, isolation, and flow direction functions being controlled by a different solenoid valve; the left steering circuit providing left steering flow during normal operation and providing both left and right steering flow during fault operation caused by a fault in the right steering circuit; and the right steering circuit providing right steering flow during normal operation and providing left and right steering flow during fault operation caused by a fault in the left steering circuit.

2. The steer-by-wire hydraulic valve of claim 1, wherein each of the left and right steering circuits include a two-position solenoid valve and a two-position spool valve that performs the flow-metering function.

3. The steer-by-wire hydraulic valve of claim 1, wherein each of the left and right steering circuits include a three-position solenoid valve and a three-position spool valve to perform both the isolation function and the flow direction function.

4. The steer-by-wire hydraulic valve of claim 1, wherein each of the left and right steering circuits include a first two-position solenoid valve and a first two-position spool valve to perform the isolation function and include a second two-position solenoid valve and a second two-position spool valve to perform the flow direction function.

5. The steer-by-wire hydraulic valve of claim 1, wherein the solenoid valve of the left steering circuit is de-energized during a fault in the left steering circuit, and wherein the solenoid valve of the right steering circuit is de-energized during a fault in the right steering circuit.

6. The steer-by-wire hydraulic valve of claim 1, wherein each of the right and left steering circuits includes a pressure reducing valve.

7. The steer-by-wire hydraulic valve of claim 1, wherein the left steering circuit and the right steering circuit are each in hydraulic communication with a same load sense shuttle valve.

8. The steer-by-wire hydraulic valve of claim 7, wherein the load sense shuttle valve communicates a maximum load sense pressure provided by a left flow-metering spool valve of the left steering circuit and a right flow-metering spool valve of the right steering circuit.

9. The steer-by-wire hydraulic valve of claim 1, further comprising a cylinder relief and anti-cavitation valve.

10. A steer-by-wire hydraulic valve comprising: a valve housing including a left steering circuit and a right steering circuit; wherein when operating under a normal mode of operation: the left steering circuit provides steering flow proportional to a left steering command to a left steering port and the right steering circuit provides steering flow proportional to a right steering command to a right steering port; and wherein when operating under a fault mode of operation, a fault having occurred in either the left steering circuit or the right steering circuit: the fault-free left or right steering circuit provides both left and right steering flows proportional to a respective left or right steering command to the respective left or right steering port.

11. The steer-by-wire hydraulic valve of claim 10, wherein each of the right and left steering circuits includes valving to perform a flow-metering function, an isolation function, and a flow direction function.

12. The steer-by-wire hydraulic valve of claim 11, wherein the flow-metering function is performed by a two-position solenoid valve and a two-position spool valve.

13. The steer-by-wire hydraulic valve of claim 11, wherein both the isolation function and the flow direction function are performed by a three-position solenoid valve and a three-position spool valve.

14. The steer-by-wire hydraulic valve of claim 11, wherein the isolation function is performed by a two-position solenoid valve and a two-position spool valve, and wherein the flow direction function is performed by a two-position solenoid valve and a two-position spool valve.

15. The steer-by-wire hydraulic valve of claim 10, wherein each of the right and left steering circuits includes a pressure reducing valve.

16. The steer-by-wire hydraulic valve of claim 10, wherein the left steering circuit and the right steering circuit are each in hydraulic communication with a same load sense shuttle valve.

17. The steer-by-wire hydraulic valve of claim 16, wherein the load sense shuttle valve communicates a maximum load sense pressure provided by a left flow-metering spool valve of the left steering circuit and a right flow-metering spool valve of the right steering circuit.

18. The steer-by-wire hydraulic valve of claim 10, further comprising a cylinder relief and anti-cavitation valve.

19. The steer-by-wire hydraulic valve of claim 10, wherein the flow from the respective left or right steering port actuates one or both of a respective left or right steering cylinder.

20. The steer-by-wire hydraulic valve of claim 10, wherein the flow from the respective left or right steering port actuates one or both of a respective left or right port of a steering actuator.

21. A steer-by-wire hydraulic valve comprising: a valve housing including: a left steering circuit having a solenoid-controlled flow-metering valve and a solenoid-controlled isolation and flow direction valve; a right steering circuit, which is identical to the left steering circuit, having a solenoid-controlled flow-metering valve and a solenoid-controlled isolation and flow direction valve; and a load sense valve in hydraulic communication with both the left and right steering circuits; the left steering circuit providing left steering flow during normal operation and providing both left and right steering flow during fault operation caused by a fault in the right steering circuit; and the right steering circuit providing right steering flow during normal operation and providing left and right steering flow during fault operation caused by a fault in the left steering circuit.

22. The steer-by-wire hydraulic valve of claim 21, wherein the solenoid control in the left steering circuit is de-energized during a fault in the left steering circuit, and wherein solenoid control in the right steering circuit is de-energized during a fault in the right steering circuit.