Variable effort steering system

Claim 2

In a vehicle having frame which supports a steering shaft for receiving torque applied manually by a driver through a steering wheel and for transmitting the manually applied torque through a steering gear to steerable wheels without power assist, a variable effort steering system comprising: a variable load actuator including a rotary member mounted upon the steering shaft, said rotary member and the steering shaft turning together in response to the manually applied torque; a stationary member at least partially surrounding said rotary member and including at least one core extending towards said rotary member; and windings surrounding at least one of said at least one core, so that when a current (I A ) is delivered through said windings, a magnetic field is produced and a holding torque (T) is exerted on said rotary member, the holding torque (T) resisting the manually applied torque and turning motion of said rotary member and the steering shaft; means for measuring a current (I A ) in communication with said windings; a sensor mounted on the frame for sensing a dynamic state of the vehicle; and an electronic control module mounted on the frame, including means for generating a first electrical signal (S 1 ) representing the dynamic state of the vehicle, said means for generating being in communication with said sensor; and means for varying the current (I A ) in response to said first electrical signal (S 1 ), said means for varying the current (I A ) being in communication with said windings of said variable load actuator and producing changes to the holding torque (T) exerted thereby upon the steering shaft in response to the dynamic state of the vehicle, thereby changing in accordance with the vehicle's dynamic state the manually applied torque required to maintain the vehicle along a desired path.

Claim 3

The variable effort steering system of claim 1, wherein said at least one core terminates adjacent said rotary member so that a gap is formed therebetween.

Claim 4

The variable effort steering system of claim 1, wherein the current (I A ) is a direct current.

Claim 5

The variable effort steering system of claim 1, wherein said at least one core comprises four cores.

Claim 6

The variable effort steering system of claim 1, wherein the dynamic state of the vehicle sensed by said sensor is vehicle speed.

Claim 7

The variable effort steering system of claim 1, wherein the dynamic state of the vehicle sensed by said sensor is lateral acceleration.

Claim 8

The variable effort steering system of claim 6, wherein the desired current (I D ) diminishes as lateral acceleration increases, thereby permitting the driver to apply prompt steering correction during skidding.

Claim 9

The variable effort steering system of claim 1, wherein the dynamic state of the vehicle sensed by said sensor is a rate of angular movement of the steering wheel.

Claim 10

The variable effort steering system of claim 8, wherein the desired current (I D ) diminishes as the rate of angular movement of the steering wheel increases, thereby decreasing the holding torque (T) during evasive maneuvers.

Claim 11

The variable effort steering system of claim 1, wherein the dynamic state of the vehicle sensed by said sensor is an angular position of the steering wheel.

Claim 12

The variable effort steering system of claim 10, wherein the desired current diminishes as the angular position of the steering wheel increases, thereby decreasing the holding torque (T) when maneuvering the vehicle in a tight turn.

Claim 13

The variable effort steering system of claim 1, wherein the dynamic state of the vehicle sensed by said sensor is vehicle speed, a rate of angular movement of the steering wheel, and an angular position of the steering wheel.

Claim 14

The variable effort steering system of claim 1, wherein the dynamic state of the vehicle sensed by said sensor is vehicle speed and an angular position of the steering wheel.

Claim 15

The variable effort steering system of claim 1, wherein the dynamic state of the vehicle sensed by said sensor is vehicle speed and a rate of angular movement of the steering wheel.

Claim 16

In a vehicle having frame which supports a steering shaft for receiving torque applied manually by a driver through a steering wheel and for transmitting the manually applied torque through a steering gear to steerable wheels without power assist, a variable effort steering system comprising: a variable load actuator including a rotary member mounted upon the steering shaft, said rotary member and the steering shaft turning together in response to the manually applied torque; a stationary member at least partially surrounding said rotary member and including at least one core extending towards said rotary member; windings surrounding at least one of said at least one core; and means for measuring a current (I A ) in communication with said windings which is delivered through said windings, a magnetic field being produced by said windings and a holding torque (T) being exerted on said rotary member, the holding torque resisting the manually applied torque and turning motion of said rotary member and the steering shaft; a sensor mounted on the frame for sensing a dynamic state of the vehicle; and an electronic control module mounted on the frame, including: means for generating a first electrical signal (S 1 ) representing a dynamic state of the vehicle, said means for generating being in communication with said sensor; and means for varying the current (I A ), including: a timing circuit in communication with said means for generating a first electrical signal (S 1 ), said timing circuit having means for measuring and storing over time (δt) a mean value of said first electrical signal (S 1 .AV) and means for measuring and storing over time (δt) a mean value of said current (I A .AV); a comparator circuit in communication with said timing circuit, having means for determining a desired current (I D ) for the dynamic state of the vehicle, and means for comparing said mean current (I A .AV) with said desired current (I D ); means for generating a second electrical signal (S 2 ) proportionate to the result of the comparison; and means for generating current changes (δI) in communication with said windings, so that the variable effort steering system delivers current changes (δI) to said windings in response to said second electrical signal (S 2 ), said holding torque (T) being modified by changes in the holding torque (δT) exerted on said rotary member by said stationary member, thereby changing in accordance with the vehicle's dynamic state the manually applied torque required to maintain the vehicle along a desired path.

Claim 17

In a vehicle having frame which supports a steering shaft for receiving torque applied manually by a driver through a steering wheel and for transmitting the manually applied torque through a steering gear to steerable wheels without power assist, a variable effort steering system comprising: a variable load actuator including a rotary member mounted upon the steering shaft, said rotary member and the steering shaft turning together in response to the manually applied torque; a stationary member at least partially surrounding said rotary member and including at least one core extending towards said rotary member; windings surrounding at least one of said at least one core; and means for measuring a current (I A ) in communication with said windings which is delivered through said windings, a magnetic field being produced by said windings and a holding torque (T) being exerted on said rotary member, the holding torque resisting the manually applied torque and turning motion of said rotary member and the steering shaft; a sensor mounted on the frame for sensing a dynamic state of the vehicle; and an electronic control module mounted on the frame, including: means for generating a first electrical signal (S 1 ) representing a dynamic state of the vehicle, said means for generating being in communication with said sensor; and means for varying the current (I A ), including: a timing circuit in communication with said means for generating a first electrical signal (S 1 ), said timing circuit having means for measuring and storing over time (δt) a mean value of said first electrical signal (S 1 .AV) and means for measuring and storing over time (δt) a mean value of said current (I A .AV); a comparator circuit in communication with said timing circuit, having means for determining a desired current (I D ) for the dynamic state of the vehicle, and means for comparing said mean current (I A .AV) with said desired current (I D ); means for generating a second electrical signal (S 2 ) proportionate to the result of the comparison; and means for generating current changes (δI) in communication with said windings, so that the variable effort steering system delivers current changes (δI) to said windings in response to said second electrical signal (S 2 ), said holding torque (T) being modified by changes in the holding torque (δT) exerted on said rotary member by said stationary member, thereby changing in accordance with the vehicle's dynamic state the manually applied torque required to maintain the vehicle along a desired path.

Claim 18

The variable effort steering system of claim 15, wherein said means for determining a desired current (I D ) for a dynamic state of the vehicle includes a matrix of values for the desired current (I D ) corresponding to the dynamic state of the vehicle.

Claim 19

The variable effort steering system of claim 15, wherein said means for determining a desired current (I D ) for a dynamic state of the vehicle includes a formula having the vehicle dynamic state as an independent variable and the desired current (I D ) as a dependent variable.