Trw Lucasvarity Electric Steering Limited

Lucas Industries Public Limited Company

Russell Wilson Jones

Anthony Walter Burton

Andrew James Stephen Williams

Simon David Stevens

Benjamin J Bradshaw

Andrew James Williams

John Nicholas Cheel

Jeffrey Ronald Coles

John M Ironside

Kevin M McLaughlin

David G Williams

Steven John Horton

Michael Holmes

Marie Saunier

Tom Michael Richard Ernest Roberts

An electric power assisted steering system is disclosed in which a torque demand signal ( ) is generated and applied to an electric motor ( ) operatively connected to a steering mechanism ( ) in order to assist a driver of the vehicle when steering the vehicle. The torque demand signal ( ) includes a damping component that is dependent upon a measurement of torque T carried by the steering mechanism and a measurement of the angular velocity &ohgr; of the steering mechanism. The torque produced by the motor ( ) is not obtrusive during &ldquo;hands-on&rdquo; maneuvers but provides enhanced damping in other maneuvers such as a steering flick.

Electrical power assisted steering systems

An electric power assisted steering system is disclosed in which a torque demand signal ( ) is generated and applied to an electric motor ( ) operatively connected to a steering mechanism ( ) in order to assist a driver of the vehicle when steering the vehicle. The torque demand signal ( ) includes a damping component that is dependent upon a measurement of torque T carried by the steering mechanism and a measurement of the angular velocity &ohgr; of the steering mechanism. The torque produced by the motor ( ) is not obtrusive during &ldquo;hands-on&rdquo; manoeuvers but provides enhanced damping in other manoeuvers such as a steering flick.

Relating to electrical power assisted steering systems

An apparatus and method for controlling an electric steering assist system, which system provides assist in response to a steering control signal, the apparatus comprising: torque sensing means ( ) operatively connected to a vehicle hand wheel ( ) for providing a torque signal (Ts) indicative of applied steering torque, blending filter means connected to the torque sensing means ( ) for providing a blended filtered torque signal having a first functional characteristic at torque frequencies less than a blending frequency and a second functional characteristic at torque frequencies greater than the blending frequency, the blending filter means including a low pass filter ( ) which passes all frequencies below the blending frequency and a high pass filter ( ) which passes all frequencies above the blending frequency, steering assist means for providing steering assist in response to a control signal, control means operatively connected to the blending filter means for providing said control signal to the steering assist means in response to the blended filtered torque signal, and means ( ) whereby high frequency gain of the steering assist system is arranged to be low for on-center operation of the hand wheel and relatively higher for off-center operation.

Method and apparatus for controlling an electric powered assisted steering system using an adaptive blending torque filter

An electric power assisted steering system of the kind in which an electric motor is operatively connected to a steering assembly through a gearbox to apply an assistance torque to the steering assembly and in which the steering assembly includes a steering column coupled at one end to a driver's handwheel and at the other end to steerable wheels, a means being provided for generating a signal representative of the velocity of rotation of the steering column. The system includes a high pass filter which is adapted to generate, for frequencies below a prescribed threshold, a signal at least approximately proportional to steering column acceleration and representative of the inertia of the rotor of the electric motor, the latter signal being arranged to be used to compensate for the motor rotor inertia in an overall assistance torque demand as developed by the system.

Compensation for motor inertia in electric power assisted steering systems

A motor control strategy for use in combination with an electric motor ( ) having a number of phase windings ( ) is disclosed, the motor ( ) being adapted to produce an output torque in response to current in the windings comprising the steps of during normal operation generating a motor torque demand signal indicative of the output torque required from the motor ( ), applying a first set of currents to the windings of the motor in response to the motor torque demand signal to produce a first output torque from the motor and during a test operation to enable diagnostics to be performed generating a motor current demand signal indicative of the total current required in the motor windings ( ) and adjusting the currents applied to one or more of the windings in response to both the torque demand signal and the motor current demand signal, whereby the adjusted currents produced in the windings are substantially equal to the total current demanded by the motor current demand signal regardless of the value of the motor torque demand signal and the motor ( ) produces a second output torque substantially equal to the first output torque produced during normal operation.

Method of controlling an electric motor having a number of phase windings

An electrical power assisted steering system is disclosed having a boost curve which has inverse symmetry about a zero input torque value, each half of the boost curve comprising a first portion defined by a first polynomial equation between a zero value and a first value, and a second portion defined by a second polynomial between a second value and a third value, in which the gradient of the first portion of the curve at the first value is equal to the gradient of the second portion of the curve at the second value. By storing values for the first, second and third values and the gradient of each polynomial at those values a smooth boost curve can be defined by storing only a small amount of parameters.

Electric power steering system with boost curve having portions defined by polynomial equations

Motor drive control

A control strategy for a multiple phase brushless motor (1) is disclosed in which the top (2, 3, 4) and the bottom (5, 6, 7) switching devices in two arms of the motor bridge are driven using complementary pulse width modulated waveforms, so that the top device (2, 3, 4) in one of the arms is in the ON state whilst the bottom device (5, 6, 7) is in the OFF state and vice versa. In an alternative arrangement, the control strategy described hereinbefore is used at high motor speeds whilst at low motor speeds a conventional modulation scheme is used in which a top switching device (2, 3, 4) in one arm of the bridge is in the ON state and a bottom device (5, 6, 7) in a different arm of the bridge is pulse width modulated. In another aspect, a method of calculating the position of the motor rotor is disclosed.

Variations in the speed of an internal combustion engine are measured and the distribution of the variations is analyzed for asymmetry, which indicates engine misfire. A threshold is generated as a function of engine speed increases and compared with engine speed decreases to detect asymmetry in the distribution.

Method of and apparatus for analyzing internal combustion engine speed

Sensors measure the temperatures of exhaust gas upstream and downstream of a catalytic converter for internal combustion engine exhaust gas. The difference between the temperatures is multiplied by the rate of mass flow of exhaust gas and the result is integrated or low pass filtered to provide a measure of converter operation. Alternatively, the multiplication is omitted and the difference between the temperatures is integrated or filtered. Thus, the performance of the catalytic converter is monitored by evaulating the difference in the heat supplied to the catalytic converter and the heat removed from the catalytic converter by the exhaust gas.

Growing community of inventors

Warwickshire, United Kingdom

Russell Wilson Jones