Abstract: When a steering speed reaches a steering speed determination threshold, a steering speed gain is set to “0”. As a result, a final basic assist controlled variable becomes “0”, and application of an assist force to a steering system is stopped. Therefore, repetition of so-called reverse assist that is a cause of occurrence of an unintended steering behavior, such as self-excited vibration, is stopped. Accordingly, the steering behavior is improved.

Abstract: An electric power steering system includes: a shaft angle sensor that outputs a signal indicating a rotation angle of a shaft through which a turning operation force is transmitted to a steering mechanism; a motor angle sensor that outputs a signal indicating a rotation angle of a motor; and a control section that determines the number of turns of the steering wheel based on both outputs of the shaft angle sensor and the motor angle sensor, wherein when it is required to determine the number of turns, the control section detects an angle error between the outputs of the shaft angle sensor and the motor angle sensor based on the outputs thereof and when the angle error falls within a predetermined allowable range, the control section determines the number of turns, and when the angle error is out of this range, the control section avoids determining the number of turns.

Abstract: When a steering speed reaches a steering speed determination threshold, a steering speed gain is set to “0”. As a result, a final basic assist controlled variable becomes “0”, and application of an assist force to a steering system is stopped. Therefore, repetition of so-called reverse assist that is a cause of occurrence of an unintended steering behavior, such as self-excited vibration, is stopped. Accordingly, the steering behavior is improved.

Abstract: A steering angle detection device includes: a shaft angle detector that detects a rotation angle of a shaft that transmits a rotation operation of a steering member to a steering mechanism; a motor angle detector that detects a rotation angle of a motor that applies a steering assist force to the steering mechanism; a steering angle calculation unit that calculates a steering angle on the basis of a combination of the rotation angle detected by the motor angle detector and the rotation angle detected by the shaft angle detector, and a temperature detector that detects an ambient temperature of the steering mechanism, wherein the steering angle calculation unit corrects the rotation angle detected by the motor angle detector or the shaft angle detector on the basis of the ambient temperature detected by the temperature detector and uses the corrected rotation angle to calculate the steering angle.

Abstract: An electric power steering system includes: a shaft angle sensor that outputs a signal indicating a rotation angle of a shaft through which a turning operation force is transmitted to a steering mechanism; a motor angle sensor that outputs a signal indicating a rotation angle of a motor; and a control section that determines the number of turns of the steering wheel based on both outputs of the shaft angle sensor and the motor angle sensor, wherein when it is required to determine the number of turns, the control section detects an angle error between the outputs of the shaft angle sensor and the motor angle sensor based on the outputs thereof and when the angle error falls within a predetermined allowable range, the control section determines the number of turns, and when the angle error is out of this range, the control section avoids determining the number of turns.

Abstract: A steering angle detection device includes: a shaft angle detector that detects a rotation angle of a shaft that transmits a rotation operation of a steering member to a steering mechanism; a motor angle detector that detects a rotation angle of a motor that applies a steering assist force to the steering mechanism; a steering angle calculation unit that calculates a steering angle on the basis of a combination of the rotation angle detected by the motor angle detector and the rotation angle detected by the shaft angle detector, and a temperature detector that detects an ambient temperature of the steering mechanism, wherein the steering angle calculation unit corrects the rotation angle detected by the motor angle detector or the shaft angle detector on the basis of the ambient temperature detected by the temperature detector and uses the corrected rotation angle to calculate the steering angle.

Abstract: A power steering apparatus according to the present invention is constructed to calculate a rate of change of steering speed detected by steering speed detecting means and judge whether the calculated rate of change is smaller than or equal to 0 or not, and reduce a gain of feedback control in comparison with a gain at the time of judgment when it is judged that the rate of change remains smaller than or equal to 0 for a predetermined time period and keep the reduced gain of feedback control until the deviation between target rotational speed and actual rotational speed of an electric motor becomes larger than 0.

Abstract: A power steering apparatus according to the present invention is constructed to calculate a rate of change of steering speed detected by steering speed detecting means and judge whether the calculated rate of change is smaller than or equal to 0 or not, and reduce a gain of feedback control in comparison with a gain at the time of judgment when it is judged that the rate of change remains smaller than or equal to 0 for a predetermined time period and keep the reduced gain of feedback control until the deviation between target rotational speed and actual rotational speed of an electric motor becomes larger than 0.

Abstract: A cylinder block for a multi-cylinder engine is provided with a water jacket partly on an intake side of a row of cylinders and partly on an exhaust side of the row of cylinders and a water guide passage through which cooling water is introduced into the water jacket. The cylinder block is provided with oil return passages each of which extends straight from top to bottom of the cylinder block between each adjacent cylinders. A branch oil return passage branches off from a middle portion of the rearmost oil return passage and extends rearward up.

Abstract: A cylinder block for a multi-cylinder engine is provided with a water jacket partly on an intake side of a row of cylinders and partly on an exhaust side of the row of cylinders and a water guide passage through which cooling water is introduced into the water jacket. The cylinder block is provided with oil return passages each of which extends straight from top to bottom of the cylinder block between each adjacent cylinders. A branch oil return passage branches off from a middle portion of the rearmost oil return passage and extends rearward up.