Fail-safe mechanism for vehicle stability augmentation steering system
First Claim
1. A vehicle steering apparatus for providing adaptive steering control and including a fail-safe mechanism, said apparatus comprising:
- steering rod means mounted for lateral movement with respect to the vehicle, said steering rod means linked at both ends to steerable wheels of the vehicle, said steering rod means for steering the vehicle by undergoing lateral movement and causing pivoting motion of the steerable wheels;
steering means for steering the vehicle by causing lateral movement of said steering rod means relative to the vehicle, said steering means including a steering wheel connected to said steering rod means;
means for providing adaptive steering control to the vehicle by causing said steering rod means to undergo lateral movement relative to the vehicle in addition to the lateral movement provided by the steering means, said means for providing adaptive steering control detecting an actual steering condition of the vehicle and comparing it with a desired steering condition of the vehicle, said additional lateral movement provided in accordance with the comparison of the actual and desired steering conditions so as to cause them to be equal, said means for providing adaptive steering control including a fluid pressure responsive means for providing the additional lateral movement to said steering rod means, fluid pressure source means for providing fluid pressure to said fluid pressure responsive means, and fail-safe valve means for controlling the flow of fluid between said fluid pressure source means and said fluid pressure responsive means, said fail-safe vale means biased so as to prevent the flow of fluid to the fluid pressure responsive means from the fluid pressure source means; and
a diagnosis circuit means for measuring the pressure and temperature of the fluid flowing between said fluid pressure responsive means and said fluid pressure source means, said diagnosis circuit means storing a threshold fluid temperature and fluid pressure, said diagnosis circuit means comparing the measured fluid temperature and fluid pressure with the stored temperature and pressure, respectively, said diagnosis circuit means causing said fail-safe valve means to prevent the flow of fluid if the measured temperature exceeds the threshold temperature or if the measured pressure is less than the threshold pressure.
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Accused Products
Abstract
The steering stability of a moving vehicle is maintained by measuring an actual yaw rate of the vehicle and determining a desired yaw rate of the vehicle and producing an output signal in response to a comparison of the actual and desired yaw rates. The steering angle of steerable wheels of the vehicle is controlled in response to the output signal in a manner tending to substantially conform the actual yaw rate to the desired yaw rate, thereby maintaining vehicle stability. The steerable wheels are steered by a steering wheel, and are independently steered by a motor in response to the output signal. The motor comprises a fluid motor. Additionally, valves are provided to stop the flow of fluid in the event that a malfunction occurs.
90 Citations
27 Claims
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1. A vehicle steering apparatus for providing adaptive steering control and including a fail-safe mechanism, said apparatus comprising:
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steering rod means mounted for lateral movement with respect to the vehicle, said steering rod means linked at both ends to steerable wheels of the vehicle, said steering rod means for steering the vehicle by undergoing lateral movement and causing pivoting motion of the steerable wheels; steering means for steering the vehicle by causing lateral movement of said steering rod means relative to the vehicle, said steering means including a steering wheel connected to said steering rod means; means for providing adaptive steering control to the vehicle by causing said steering rod means to undergo lateral movement relative to the vehicle in addition to the lateral movement provided by the steering means, said means for providing adaptive steering control detecting an actual steering condition of the vehicle and comparing it with a desired steering condition of the vehicle, said additional lateral movement provided in accordance with the comparison of the actual and desired steering conditions so as to cause them to be equal, said means for providing adaptive steering control including a fluid pressure responsive means for providing the additional lateral movement to said steering rod means, fluid pressure source means for providing fluid pressure to said fluid pressure responsive means, and fail-safe valve means for controlling the flow of fluid between said fluid pressure source means and said fluid pressure responsive means, said fail-safe vale means biased so as to prevent the flow of fluid to the fluid pressure responsive means from the fluid pressure source means; and a diagnosis circuit means for measuring the pressure and temperature of the fluid flowing between said fluid pressure responsive means and said fluid pressure source means, said diagnosis circuit means storing a threshold fluid temperature and fluid pressure, said diagnosis circuit means comparing the measured fluid temperature and fluid pressure with the stored temperature and pressure, respectively, said diagnosis circuit means causing said fail-safe valve means to prevent the flow of fluid if the measured temperature exceeds the threshold temperature or if the measured pressure is less than the threshold pressure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A steering control apparatus for a vehicle comprising:
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a rack mounted for lateral movement with respect to the vehicle, said rack including a housing; a steering input means including a steering wheel linked to said rack for providing lateral movement or said rack; a steering rod mounted for lateral movement with and with respect to said rack, said rod including a piston disposed thereon and within said housing, said piston dividing said housing into first and second fluid chambers, said steering rod linked at both ends to steerable wheels of the vehicle; fluid pressure source means for providing fluid pressure to said chambers, lateral movement of said rack thereby transferred to said rod through the fluid pressure in said chambers; fail-safe valve means for linking said fluid pressure source means and said housing in fluid communication, said fail safe valve means biased so as to be closed and thereby prevent fluid flow to said housing from said fluid pressure source means; control means for detecting an actual steering condition of the vehicle and for determining a desired steering condition, said control means comparing the actual steering condition and the desired steering condition and activating said fail-safe valve means to control the link between said fluid chambers and said fluid pressure source means to pressurize one chamber with respect to the other chamber and thereby cause said piston to move within said housing and further causing said steering rod to move relative to said rack to provide additional steering to the steerable wheels on the basis of the comparison; and a diagnosis circuit means for measuring the pressure and temperature of the fluid flowing between said housing and said fluid pressure source means, said diagnosis circuit means storing a threshold fluid temperature and fluid pressure, said diagnosis circuit means comparing the measured fluid temperature and fluid pressure with the stored temperature and pressure, respectively, said diagnosis circuit means causing said fail-safe valve means to prevent the flow of fluid if the measured temperature exceeds the threshold temperature or if the measured pressure is less than the threshold pressure. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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25. An apparatus for steering a motor vehicle, the vehicle comprising steerable wheels and steering arms connected to said steerable wheels, said apparatus comprising:
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a movable rack; main steering means including a steering wheel connected to said movable rack for moving said movable rack; fluid motor means operably interconnecting said movable rack and the steering arms, said motor means for transmitting steering forces from said movable rack to the steerable wheels through the steering arms, said motor means comprising relatively movable first and second parts, said first part connected to said movable rack and said second part connected to said steering arm; control means for measuring an actual vehicle steering condition, for determining a desired vehicle steering condition, and for generating an output signal in response to a comparison of the desired and actual vehicle steering conditions, said controls means operably connected to said motor means whereby said motor means is actuated in response to the output signal to steer the steerable wheels independently of movement of said rack; fail-safe valve means for controlling the flow of fluid to and from said fluid motor means, the opening and closing of said fail-safe valve means controlled by said control means, said fail-safe valve means normally biased into a closed position to isolate said fluid motor means from the flow of fluid; and a diagnosis circuit means for measuring the pressure and temperature of the fluid flowing to and from said motor means, said diagnosis circuit means storing a threshold fluid temperature and fluid pressure, said diagnosis circuit means comparing the measured fluid temperature and fluid pressure with the stored temperature and pressure, respectively, said diagnosis circuit means causing said fail-safe valve means to prevent the flow of fluid if the measured temperature exceeds the threshold temperature or if the measured pressure is less than the threshold pressure. - View Dependent Claims (26, 27)
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Specification