Abstract: A driver device for a duty solenoid valve comprises a pair of transistors 27 and 31 for controlling the excitation current level flowing through the solenoid 17 of the valve, and a transistor 45 for turning on and off the excitation current. The excitation current level is detected via an integrator 63 and A/D converter 61 by a microcomputer 62. In response to the detected excitation current level, the microcomputer 62 generates a first pulse signal (PWM signal) via OUT3 to control the level of the excitation current to a target level. Further, the microcomputer 62 outputs a second pulse signal via the OUT4 to the transistor 45 to control the duty ratio of the solenoid 17.

Abstract: The power steering system of this invention has a motor which provides auxiliary torque for the steering shaft to assist in steering.The maximum level of the motor current is varied in response to the mean motor current at predetermined intervals of time so as to regulate the maximum motor current and thereby prevent overheating or burning of the motor when, for example, the steering wheel is held for a long time in an extreme position.

Abstract: An electric power steering device is disclosed which comprises a fail-safe relay. The circuitry for operating the relay comprises the following: the neutral region detector circuit which generates an output when the steering torque applied by the operator is in the neutral region; a motor current detector circuit for detecting the motor current; an AND gate having inputs coupled to the above two circuits; a self-hold circuit for holding the output of the AND gate; and a relay interrupting circuit for interrupting the relay in response to the output of the self-hold circuit. Thus, the fail-safe relay is interrupted to disconnect the battery from the motor and clutch when the motor is energized in spite of the fact that the steering torque by the operator of the vehicle is in the neutral region.

Abstract: An electric power steering apparatus for an automotive vehicle has an interrupter which cuts off the power to a drive motor when a dangerous situation is detected. In one form of the invention, the interrupter cuts off power to the drive motor when a ground fault sensor detects a ground fault of a motor driver and there is disagreement between a directional drive signal to the drive motor and the direction of torque applied to the steering wheel by the driver. In another form of the invention, the interrupter circuit cuts off power when the vehicle speed exceeds a prescribed level and the torque applied to the steering wheel exceeds a prescribed level for a certain length of time. In a third form of the invention, the interrupter cuts off power when the motor current exceeds a prescribed level and disagreement of directional signals is detected.

Abstract: An electric power steering device having a clutch 25 for connecting and disconnecting the motor 14 to and from the steering shaft is disclosed, the control circuit of which comprises, in addition to a microcomputer 3, an additional analog direction determiner circuit 17, and a first and a second logical circuit. The first logical circuit consists of a pair of AND gates 20A, 20B generates a final right or left direction signal supplied to the motor driver circuit. The second logical circuit consists of a pair of exclusive OR gates 21A, 21B and an AND gate 22 and supplies a deenergization signal to the clutch driver when the directions determined by the microcomputer and the analog direction determiner circuit disagree.

Abstract: An electric power steering apparatus for an automotive vehicle has an interrupter which cuts off the power to a drive motor when a dangerous situation is detected. In one form of the invention, the interrupter cuts off power to the drive motor when a ground fault sensor detects a ground fault of a motor driver and there is disagreement between a directional drive signal to the drive motor and the direction of torque applied to the steering wheel by the driver. In another form of the invention, the interrupter circuit cuts off power when the vehicle speed exceeds a prescribed level and the torque applied to the steering wheel exceeds a prescribed level for a certain length of time. In a third form of the invention, the interrupter cuts off power when the motor current exceeds a prescribed level and disagreement of directional signals is detected.

Abstract: A motor-driven power assisted steering control apparatus includes a steering torque sensor 1, a motor 14 connected to a steering shaft via a clutch to exert an auxiliary steering force, and circuitry for controlling the motor in correspondence to an output from the steering torque sensing means. A torque neutral point detector 23 detects the neutral point of the steering torques, and first and second level detecting circuits 27, 29 detect when the motor current exceeds first and higher second levels, respectively. When the motor current exceeds the first level with the steering torque value at other than the neutral point, the clutch current is reduced to cause slippage, and when the motor current exceeds the second level with the steering torque value at other than the neutral point, the clutch current is interrupted to thereby stop the motor.

Abstract: An electric motor assisted power steering device for an automobile is disclosed which comprises a dupicate torque direction determination system. The power steering device comprises, in addition to a microcomputer for determining the amount and direction of the auxiliary torque which is to be provided by the electric motor, an analog direction determiner circuit for determining the direction of the auxiliary torque. The torque sensor outputs a voltage which is substantially in linear relationship with the steering torque applied by the operator. The direction determiner circuit includes: a first comparator which outputs a right direction signal when this output voltage of the torque sensor exceeds a first reference level; and a second comparator which outputs a left direction signal when the output voltage of the torque sensor is below a second reference level which is lower than the first level.

Abstract: A direction display system utilizing a traveling azimuth of a vehicle and an angular coordinate of the vehicle on polar coordinates with an origin set at a specified location to determine a direction of the specified location to be displayed by the use of an indicator taken with reference to a pictorial display pattern of the vehicle. The traveling azimuth may also be used to determine a traveling direction of the vehicle so that both the direction of the specified location and the traveling direction of the vehicle can be selectively displayed on a single display unit operated by a switch.