Electric power assist torque check
First Claim
1. A power steering system for a vehicle, comprising:
- a steering system having an assist mechanism with at least one motor for power steering;
a sensor for sensing at least one of a steering angle and a steering torque by a driver of the vehicle; and
at least one controller for receiving inputs from the sensors and from the motor for calculating an output torque of the assist mechanism and for comparing said output with the steering torque, wherein the at least one controller uses an algorithm to calculate the output torque by the assist mechanism and determines whether a relationship between the steering wheel torque and the assist mechanism torque is within acceptable bounds; and
wherein the at least one controller uses an algorithm for calculating motor assist torque, wherein torque equals
sqrt(⅔
) *Kt2*[Ia*sin(Θ
)+Ib*sin (Θ
−
2π
/3)+Ic*sin (Θ
+2π
/3)], where Kt2 is a constant factor for a particular motor, Ia, Ib and Ic are motor phase currents, and Θ
is a rotor mechanical angle times a number of pole pairs of the motor.
5 Assignments
0 Petitions
Accused Products
Abstract
A power steering system includes at least one motor to assist the operator of a vehicle in turning the wheels and steering the vehicle and at least one computer or microprocessor controller. One of the processors adjusts the motor assist torque to reduce the driver effort based on specified requirements defined by boost curves. A second microprocessor controller uses an algorithm to calculate the output of the power steering motor, and compare the relationship between the driver torque and the power assist torque. If the relationship between the two is out of specified bounds, then the power steering assist is deemed inappropriate and the power system may go to a power-off state to assure that the motor does not generate an undesirable torque that has not been requested by the driver.
58 Citations
18 Claims
-
1. A power steering system for a vehicle, comprising:
-
a steering system having an assist mechanism with at least one motor for power steering;
a sensor for sensing at least one of a steering angle and a steering torque by a driver of the vehicle; and
at least one controller for receiving inputs from the sensors and from the motor for calculating an output torque of the assist mechanism and for comparing said output with the steering torque, wherein the at least one controller uses an algorithm to calculate the output torque by the assist mechanism and determines whether a relationship between the steering wheel torque and the assist mechanism torque is within acceptable bounds; and
wherein the at least one controller uses an algorithm for calculating motor assist torque, wherein torque equals
sqrt(⅔
) *Kt2*[Ia*sin(Θ
)+Ib*sin (Θ
−
2π
/3)+Ic*sin (Θ
+2π
/3)],where Kt2 is a constant factor for a particular motor, Ia, Ib and Ic are motor phase currents, and Θ
is a rotor mechanical angle times a number of pole pairs of the motor.- View Dependent Claims (2, 3, 4, 5, 8)
-
-
6. A method for controlling power steering, the method comprising:
-
providing a power steering system for a vehicle selected from the group consisting of an automobile and a truck;
measuring a steering torque by a driver of the vehicle;
measuring an output torque of the power steering system using an algorithm, said measurement using an algorithm wherein torque equals;
sqrt(⅔
) *Kt2*[Ia*sin(Θ
)+Ib*sin (Θ
−
2π
/3)+Ic*sin (Θ
+2π
/3)],where Kt2 is a constant factor for a particular motor, Ia, Ib and Ic are motor phase currents, and θ
is a rotor mechanical angle times a number of pole pairs of the motor;
comparing the output torque of the power steering system with the steering torque by the driver; and
adjusting the output of the power steering system if a relationship between the output torques does not meet specified criteria. - View Dependent Claims (7, 9, 10, 11)
-
-
12. A power steering system for a vehicle comprising:
-
a steering system connected to two steered wheels of a vehicle selected from the group consisting of an automobile and a truck, said steering system having an assist mechanism for power steering using at least one motor;
a sensor connected to a steering wheel in the steering system, the sensor capable of sensing a steering torque; and
at least one controller receiving inputs from the sensor and the motor and running an algorithm for calculating an output of the assist mechanism, wherein the controller compares the output of the assist mechanism with the steering torque to determine whether a relationship between the output of the assist mechanism and the steering torque is appropriate for a desirable level of assistance, and wherein said algorithm for calculating an assist mechanism motor torque is, motor torque=sqrt(⅔
)*Kt2*[Ia* sin (Θ
)+Ib* sin (Θ
−
2π
/3)+Ic* sin (Θ
+2π
/3)],where Kt2 is a constant factor for a particular motor, Ia, Ib and Ic are motor phase currents, and Θ
is a motor mechanical angle times a number of pole pairs of the motor. - View Dependent Claims (13, 14, 15, 16)
-
-
17. A power steering system for a vehicle comprising:
-
a steering system connected to two steered wheels of a vehicle, said steering system having a power assist mechanism with a motor;
a sensor connected to a steering wheel in the steering system for sensing a steering torque; and
at least one controller receiving inputs from the sensor and the motor and running an algorithm for calculating an output of the assist mechanism, wherein the controller compares the output of the assist mechanism with the steering torque to determine whether a relationship between the output of the assist mechanism and the steering torque is appropriate for a desired level or assistance, and wherein said algorithm for calculating an assist motor torque uses the equation where torque equals
sqrt(⅔
) *Kt2*[Ia*sin(Θ
)+Ib*sin (Θ
−
2π
/3)+Ic*sin (Θ
+2π
/3)],where Kt2 is a constant factor for a particular motor, Ia, Ib and Ic are motor phase currents, Θ
is a motor mechanical angle times a number of pole pairs of the motor. - View Dependent Claims (18)
-
Specification