Electric steering gear

A steering assembly for turning the steerable wheels of a vehicle upon rotation of the vehicle steering wheel, said assembly comprising:

• means for mechanically coupling the vehicle steering wheel with the steerable wheels of the vehicle including,
• an input shaft connected to said steering wheel for rotation therewith,
• a pinion gear,
• a torsion member resiliently connecting said input shaft to said pinion gear, and
• a steering member having rack teeth thereon drivingly engaged by said pinion gear and connected to said steerable wheels of said vehicle, rotary motion of said pinion gear axially driving said steering member to turn said steerable wheels;
• torsion sensing means for generating a first electric torsion signal and a second electric torsion signal, each said first electric torsion signal and said second electric torsion signal varying as a function of the amount of input torque applied to said steering wheel, said first and second electric torsion signals (i) being at a substantially equal value when no torque is applied to the vehicle steering wheel and (ii) varying oppositely from said substantially equal value upon application of input torque to the steering wheel;
• electronic control means connected to said torsion sensing means including means for generating a control signal dependent upon one of said two generated electric torsion signals and means for verifying said control signal with the other of said generated electric torsion signals;
• and
• electric power assist motor drivably connected directly to at least one of said input shaft, said pinion gear or said steering member for assisting movement thereof in response to said control signal.

A steering assembly for turning the steerable wheels of a vehicle upon rotation of the vehicle steering wheel, said assembly comprising:

• means for mechanically coupling the vehicle steering wheel with the steerable wheels of the vehicle including,
• an input shaft connected to said steering wheel for rotation therewith,
• a pinion gear,
• a torsion member resiliently connecting said input shaft to said pinion gear, and
• a steering member having rack teeth thereon drivingly engaged by said pinion gear and connected to said steerable wheels of said vehicle, rotary motion of said pinion gear axially driving said steering member to turn said steerable wheels;
• torsion sensing means for generating a first electric torsion signal and a second electric torsion signal, each said first electric torsion signal and said second electric torsion signal varying as a function of the amount of input torque applied to said steering wheel, said first and second electric torsion signals being respectively at a first and a second value when no torque is applied to the vehicle steering wheel and varying therefrom upon application of input torque to the steering wheel;
• electronic control means connected to said torsion sensing means including means for generating a control signal dependent upon one of said two generated electric torsion signals;
• and
• electric power assist motor drivably connected direct to at least one of said input shaft, said pinion gear or said steering member for assisting movement thereof in response to said control signal;
• said electronic control means further including means responsive to the other of said two generated electric torsion signals and to the control signal for determining when high assist is being commanded by said control signal but is not justified by a correspondingly high value of said other of said two generated electric torsion signals, and means for disabling operation of said electric power assist motor upon said determination.

A steering assembly for turning the steerable wheels of a vehicle upon rotation of the vehicle steering wheel, said assembly comprising:

• means for mechanically coupling the vehicle steering wheel with the steerable wheels of the vehicle including,
• an input shaft connected to said steering wheel for rotation therewith,
• a pinion gear,
• a torsion member resiliently connecting said input shaft to said pinion gear, and
• a steering member having rack teeth thereon drivingly engaged by said pinion gear and connected to said steerable wheels of said vehicle, rotary motion of said pinion gear axially driving said steering member to turn said steerable wheels;
• torsion sensing means for generating a first electric torsion signal and a second electric torsion signal, each said first electric torsion signal and said second electric torsion signal varying as a function of the amount of input torque applied to said steering wheel, said first and second electric torsion signals being respectively at a first and a second value when no torque is applied to the vehicle steering wheel and varying therefrom upon application of input torque to the steering wheel;
• electronic control means connected to said torsion sensing means including means for generating a control signal dependent upon one of said two generated electric torsion signals;
• and
• electric power assist motor drivably connected directly to at least one of said input shaft, said pinion gear or said steering member for assisting movement thereof in response to said control signal;
• said electronic control means further including means for determining if the control signal would cause said electric power assist motor to be driven in a direction consistent with the direction indicated by said other of said generated electric torsion signals, and means for disabling operation of said electric power assist motor when a determination is made that said electric power assist motor would be driven in a direction not consistent with the direction indicated by said other of said generated electric torsion signals.

A steering assembly for turning the steerable wheels of a vehicle upon rotation of the vehicle steering wheel, said assembly comprising:

• means for mechanically coupling the vehicle steering wheel with the steerable wheels of the vehicle including,
• an input shaft connected to said steering wheel for rotation therewith,
• a pinion gear,
• a torsion member resiliently connecting said input shaft to said pinion gear, and
• a steering member having rack teeth thereon drivingly engaged by said pinion gear and connected to said steerable wheels of said vehicle, rotary motion of said pinion gear axially driving said steering member to turn said steerable wheels;
• torsion sensing means for generating a first electric torsion signal and a second electric torsion signal, each said first electric torsion signal and said second electric torsion signal being respectively at a first and a second value when no torque is applied to the vehicle steering wheel and varying with bilateral symmetry upon applied input torque to the steering wheel such that the sum of the first and second generated electric torsion signal remains substantially constant independent of the applied input torque;
• electronic control means connected to said torsion sensing means including means for generating a control signal dependent upon one of said two generated electric torsion signals;
• and
• electric power assist motor drivably connected directly to at least one of said input shaft, said pinion gear or said steering member for assisting movement thereof in response to said control signal;
• said electronic control means further including means for establishing a value for each said first electric torsion signal and said second generated electric torsion signal, means for adding the established values for said first and said second generated electric torsion signals, means for determining if said added values of said first and said second generated electric torsion signals varies from a predetermined value by more than a predetermined amount, and means for disabling operation of said electric power assist motor upon a determination that said added values varies from said predetermined value by more than said predetermined amount.

A steering assembly for turning the steerable wheels of a vehicle upon rotation of the vehicle steering wheel, said assembly comprising:

• means for mechanically coupling the vehicle steering wheel with the steerable wheels of the vehicle including,
• an input shaft connected to said steering wheel for rotation therewith,
• a pinion gear,
• a torsion member resiliently connecting said input shaft to said pinion gear, and
• a steering member having rack teeth thereon drivingly engaged by said pinion gear and connected to said steerable wheels of said vehicle, rotary motion of said pinion gear axially driving said steering member to turn said steerable wheels;
• torsion sensing means for generating a first electric torsion signal and a second electric torsion signal, each said first electric torsion signal and said second electric torsion signal varying as a function of the amount of input torque applied to said steering wheel, said first and second electric torsion signals being respectively at a first and a second value when no torque is applied to the vehicle steering wheel and varying therefrom upon application of input torque to the steering wheel;
• electronic control means connected to said torsion sensing means including means for generating a control signal dependent upon one of said two generated electric torsion signals;
• and
• electric power assist motor drivably connected directly to at least one of said input shaft, said pinion gear or said steering member for assisting movement thereof in response to said control signal;
• said electronic control means further including means for comparing each said first electric torsion signal and said second generated electric torsion signal against a maximum and minimum predetermined value and means for disabling operation of said electric power assist motor when said means for comparing determines either said first or said second generated electric torsion signal is outside of said predetermined maximum and minimum values.

A method for controlling a vehicle power assist steering assembly having a vehicle steering wheel mechanically coupled to steerable wheels of the vehicle and power assist means for assisting a vehicle operator in a steering maneuver with an amount of assist available being responsive to an electrical control signal, said method comprising the steps of:

• (a) generating a first electric torsion signal which varies as a function of applied steering torque;
• (b) generating a second electric torsion signal which varies as a function of applied steering torque so as to be of substantially equal value as said first electric torsion signal when no torque is applied to the vehicle steering wheel and varying oppositely from said first electric torsion signal upon application of input torque to the vehicle steering wheel;
• (c) generating the control signal dependent upon the generated first electric torsion signal;
• (d) verifying the control signal with the second generated electric torsion signal;
• and
• (e) disabling the power assist means if the control signal verification indicates a fault condition.

A method for controlling a vehicle power assist steering assembly having a vehicle steering wheel mechanically coupled to steerable wheels of the vehicle and power assist means for assisting a vehicle operator in a steering maneuver with an amount of assist available being responsive to an electrical control signal, said method comprising the steps of:

• (a) generating a first electric torsion signal which varies as a function of applied steering torque;
• (b) generating a second electric torsion signal which varies as a function of applied steering torque so as to be of substantially equal value as said first electric torsion signal when no torque is applied to the vehicle steering wheel and varying oppositely from said first electric torsion siqnal upon application of input torque to the vehicle steering wheel;
• (c) generating the control signal dependent upon the generated first electric torsion signal;
• (d) determining when high assist is being commanded by said control signal;
• (e) verifying that said high assist being commanded is justified by said second electric torsion signal;
• and
• (f) disabling the power assist means if the verification indicates excess assist is being commanded.

A method for controlling a vehicle power assist steering assembly having a vehicle steering wheel mechanically coupled to steerable wheels of the vehicle and power assist means for assisting a vehicle operator in a steering maneuver with an amount of assist available being responsive to an electrical control signal, said method comprising the steps of:

• (a) generating a first electric torsion signal which varies as a function of applied steering torque;
• (b) generating a second electric torsion signal which varies as a function of applied steering torque so as to be of substantially equal value as said first electric torsion signal when no torque is applied to the vehicle steering wheel and varying oppositely from said first electric torsion signal upon application of input torque to the vehicle steering wheel;
• (c) generating the control signal having a direction component dependent upon the generated first electric torsion signal to provide power assist in a direction;
• (d) verifying the direction component of the generated control signal with the second generated electric torsion signal;
• and
• (e) disabling the power assist means if the control signal verification indicates a fault condition.

A method for controlling a vehicle power assist steering assembly having a vehicle steering wheel mechanically coupled to steerable wheels of the vehicle and power assist means for assisting a vehicle operator in a steering maneuver with an amount of assist available being responsive to an electrical control signal, said method comprising the steps of:

• (a) generating a first electric torsion signal which varies as a function of applied steering torque;
• (b) generating a second electric torsion signal which varies a function of applied steering torque so as to be of substantially equal value as said first electric torsion signal when no torque is applied to the vehicle steering wheel and varying oppositely from said first electric torsion signal upon application of input torque to the vehicle steering wheel;
• (c) generating the control signal dependent upon the generated first electric torsion signal;
• (d) comparing the first and second generated electric torsion signals against minimum and maximum predetermined limits;
• and
• (e) disabling the power assist means if the first or second generated electric torsion signals are outside of the minimum or maximum predetermined limits.

A method for controlling a vehicle power assist steering assembly having a vehicle steering wheel mechanically coupled to steerable wheels of the vehicle and power assist means for assisting a vehicle operator in a steering maneuver with an amount of assist available being responsive to an electrical control signal, said method comprising the steps of:

• (a) generating a first electric torsion signal which varies as a function of applied steering torque;
• (b) generating a second electric torsion signal which varies as a function of applied steering torque so as to be of substantially equal value as said first electric torsion signal when no torque is applied to the vehicle steering wheel and varying oppositely from said first electric torsion signal upon application of input torque to the vehicle steering wheel;
• (c) generating the control signal dependent upon the generated first electric torsion signal;
• (d) adding values indicative of said first and second generated electric torsion signals;
• (e) comparing said added values indicative of said first and second generated electric torsion signals against a predetermined value range;
• and
• (f) disabling the power assist means if the added values indicative of said first and second generated electric torsion signals are outside of said predetermined value range.