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All commonly used speed sensitive power steering assist systems for cars are based on hydraulics. These systems change the pressure or modulate the flow of the conventional hydraulic power steering system. They require some means of actuation in the form of an electromagnetic device such as a solenoid actuator working as a flow or pressure regulator or brushless motor driving a hydraulic pump. Usually they are pulse width modulated controlled by a microprocessor. Therefore, these systems can be quite complicated. This paper describes MAGNASTEER, a novel magnetic speed sensitive system developed at Saginaw Division in cooperation with the NAO Research and Development Center, which is an add on to the basic hydraulic power steering system. The effort variation provided by MAGNASTEER is the result of an electronically controlled electromagnetic torque, which acts as an addition or subtraction to the torsion bar torsional rate, effectively varying the feel of the hydraulic system.

All commonly used speed sensitive power steering assist systems for cars are based on hydraulics. These systems [ILLEGIBLE]ange the pressure or modulate the flow of the conventional [ILLEGIBLE]draulic power steering system. They require some means of [ILLEGIBLE]ctuation in the form of an electromagnetic device such as a solenoid actuator working as a flow pressure regulator or brushless motor driving a hydraulic pump. Usually they are pulse width modulated controlled by a microprocessor. Therefore, these systems can be quite complicated. This paper describes MAGNASTEER a novel magnetic speed sensitive system developed at General Motors Corporation. The effort variation provided by MAGNASTEER is the result of an electronically controlled electromagnetic torque, which acts as an addition or subtraction to the torsion bar torsional rate, effectively varying the feel of the hydraulic system.

Variable reluctance sensors are widely used in automotive applications and well known for their low cost and reliability. Because of recent developments of new magnetic materials and manufacturing technologies, it was possible to introduce new sensor configurations which can lead to dramatic improvement in sensor performance. This paper describes a novel variable reluctance speed sensor with two permanent magnets located in the proximity of an exciter wheel and presents the magnetic analysis of this sensor. This novel sensor configuration has the ability to develop high signal strength over the high temperature range at low exciter wheel speeds and a large air gap between the sensor and the exciter wheel. In applications where the available space for the sensor is limited, it shows much better performance than prior art sensors. The sensor structure is devised to fit a very limited space and to provide high performance signal for a variety of applications.