Motor-driven power steering system for a vehicle
First Claim
1. A motor-driven power steering system for a vehicle comprising:
- a steering wheel;
a steering shaft fixedly connected with said steering wheel for integral rotation therewith;
a speed sensor connected to detect travelling speed of the vehicle and generating an output signal representative of the detected vehicle speed;
a torque sensor mounted on said steering shaft for detecting operator-induced steering torque resulting from steering force exerted on said steering wheel by an operator and generating an output signal representative of the detected steering torque;
a first pinion operatively connected with said steering shaft and adapted to be driven by said steering wheel through an intermediary of said steering shaft;
a rack operatively connected through tie rods with a pair of steerable road wheels and having a first rack tooth portion and a second rack tooth portion formed thereon, said first rack tooth portion being in meshing engagement with said first pinion;
a second pinion being in meshing engagement with said second rack tooth portion on said rack;
a motor operatively connected through a speed-reduction gear with said second pinion for power assisting a steering motion of said rack induced by the operator through an intermediary of said steering wheel, said steering shaft, said first pinion, and said first rack tooth portion;
a first electromagnetic clutch interposed between said motor and said second pinion for transmitting power therebetween substantially in proportion to a current suplied thereto;
a second clutch interposed between said motor and said second pinion for selectively establishing and disconnecting the operative connection therebetween; and
a control unit adapted to receive output signals from said speed sensor and said torque sensor for controlling the operations of said motor, said first clutch, and said second clutch.
1 Assignment
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Accused Products
Abstract
A motor-driven power steering system for a vehicle preventing transmission of operating noises of the motor to the interior of the passenger compartment of the vehicle and for suppressing the generation of radio wave noises: a speed sensor for detecting the travelling speed of the vehicle; a torque sensor mounted on a steering shaft for detecting turning force imparted to the steering wheel by an operator, a first pinion operatively connected with the steering shaft and adapted to be driven by the steering wheel through the intermediary of the steering shaft, a rack operatively connected through tie rods with a pair of steerable road wheels and having a first rack tooth portion and a second rack tooth portion formed thereon, a second pinion being in meshing engagement with the second rack tooth portion on the rack, a motor operatively connected with the second pinion for power assisting the steering motion of the rack induced by the operator a first electromagnetic clutch interposed between the motor and the second pinion for transmitting power therebetween substantially in proportion to the intensity of current supplied thereto, a second clutch interposed between the motor and the second pinion for selectively establishing or disconnecting the operative connection between the motor and the second pinion, and a control unit adapted to receive output signals from the speed sensor and the torque sensor for controlling the operations of the motor, the first clutch and the second clutch.
25 Citations
21 Claims
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1. A motor-driven power steering system for a vehicle comprising:
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a steering wheel; a steering shaft fixedly connected with said steering wheel for integral rotation therewith; a speed sensor connected to detect travelling speed of the vehicle and generating an output signal representative of the detected vehicle speed; a torque sensor mounted on said steering shaft for detecting operator-induced steering torque resulting from steering force exerted on said steering wheel by an operator and generating an output signal representative of the detected steering torque; a first pinion operatively connected with said steering shaft and adapted to be driven by said steering wheel through an intermediary of said steering shaft; a rack operatively connected through tie rods with a pair of steerable road wheels and having a first rack tooth portion and a second rack tooth portion formed thereon, said first rack tooth portion being in meshing engagement with said first pinion; a second pinion being in meshing engagement with said second rack tooth portion on said rack; a motor operatively connected through a speed-reduction gear with said second pinion for power assisting a steering motion of said rack induced by the operator through an intermediary of said steering wheel, said steering shaft, said first pinion, and said first rack tooth portion; a first electromagnetic clutch interposed between said motor and said second pinion for transmitting power therebetween substantially in proportion to a current suplied thereto; a second clutch interposed between said motor and said second pinion for selectively establishing and disconnecting the operative connection therebetween; and a control unit adapted to receive output signals from said speed sensor and said torque sensor for controlling the operations of said motor, said first clutch, and said second clutch. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A motor-driven power steering system for a vehicle comprising:
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a steering wheel; a steering shaft fixedly connected with said steering wheel for integral rotation therewith; a vehicle-speed sensor connected to detect travelling speed of the vehicle and generating an output signal representative of the detected vehicle speed; a torque sensor mounted on said steering shaft for detecting operator-induced steering torque resulting from steering force exerted on said steering wheel by an operator and generating an output signal representative of the detected steering torque; a steering-speed sensor for detecting the steering speed of said steering wheel and generating an output signal representative of the detected steering speed; a first pinion operatively connected with said steering shaft and adapted to be driven by said steering wheel through an intermediary of said steering shaft; a rack operatively connected through tie rods with a pair of steerable road wheels and having a first rack tooth portion and a second rack tooth portion formed thereon, said first rack tooth portion being in meshing engagement with said first pinion; a second pinion being in meshing engagement with said second rack tooth portion on said rack; a motor operatively connected through a speed-reduction gear with said second pinion for power assisting the steering motion of said rack induced by the operator through an intermediary of said steering wheel, said steering shaft, said first pinion, and said first rack tooth portion; a first electromagnetic clutch interposed between said motor and said second pinion for transmitting power therebetween substantially in proportion to a current supplied thereto; a second clutch interposed between said motor and said second pinion for selectively establishing and disconnecting the operative connection therebetween; and a control unit adapted to receive output signals from said speed sensor, said torque sensor, and said steering-speed sensor for controlling the operations of said motor, said first clutch, and said second clutch. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification