Abstract: A shaft coupling mechanism 1 for an electric power steering apparatus includes a coupling base body 3 coupled to a rotating shaft 2; a coupling base body 5 coupled to a steering shaft 4 serving as a rotating shaft; and a pair of rotation transmitting members 6 and 7 which are disposed between the rotating shaft 2 and the steering shaft 4 by means of both coupling base bodies 3 and 5 and transmit the rotation of the rotating shaft 2 to the steering shaft 4.

Abstract: In an electric power steering apparatus which comprises a motor for generating steering assist force, it is judged whether or not the vehicle is in a state of straight forward motion. A mean reference steering angle is determined by dividing total of relative steering angles which are determined when the vehicle is judged to be in a state of straight forward motion by the number of judgments that the vehicle is in a state of straight forward motion. A steering angle is determined by subtracting a steering angle midpoint from a relative steering angle with taking the mean reference steering angle as the steering angle midpoint. The output of the motor for generating steering assist force is corrected in accordance with an output correction value determined on the basis of the determined steering angle. This output correction value is altered so as to have a positive correlation with the number of judgments that the vehicle is in a state of straight forward motion.

Abstract: A torque detecting apparatus having a permanent magnet fixed to an input shaft, magnetic yokes fixed to an output shaft coaxially connected to the input shaft via a torsion bar and disposed within a magnetic field of the permanent magnet to form a magnetic circuit, and a Hall IC for detecting a magnetic flux induced by the magnetic yokes. The permanent magnet is of a truncated conical shape, and the bevel circumference surface thereof is magnetized by magnetic poles alternately in a reverse polarities along circumference direction, so as to oppose the magnetic yokes. A torque applied to the input shaft or the output shaft can be detected through detection by the Hall IC of the magnetic flux generated between the magnetic yokes. The configuration allows reducing the length in an axial direction of the input shaft.

Abstract: An electric power steering apparatus comprises a steering assisting electric motor having an output shaft and a speed reduction mechanism. The speed reduction mechanism includes conical first and second gears to be engaged with each other. The first and second gears include a plurality of teeth each having a tooth surface. The mutually corresponding tooth surfaces of the first and second gears each include engaging regions to be engaged with each other. A center position in a tooth width direction of the engaging region of each tooth surface of the first gear in an unloaded state is offset by a first offset amount from center position in the tooth width direction of the tooth surface of the first gear to a relatively small end portion of the tooth of the first gear.

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: In a torque sensor having lead pins connected to a wire harness, the wire harness includes: a plurality of lead wires; a plurality of connection terminals each having a sleeve mounted around each of the lead pins and a connection portion extended from an outer periphery of the sleeve to be connected with one end of the lead wire; and an electrically insulating terminal holder for holding the plural connection terminals. The terminal holder includes: a sleeve holder portion for holding the sleeves in mutually spaced relation in order to prevent the sleeves from contacting each other; and a connection-portion holder portion for holding the connection portions in mutually spaced relation in order to prevent the connection portions from bending to contact each other.

Abstract: A transformer section transforms a primary voltage and outputs secondary voltage. A control section inputs a first signal indicating a state of electricity supply of a primary power source through an in-vehicle network. The transformer section outputs a second signal indicating a state of electricity supply of the transformer section. When the input of the first signal is disrupted, the control section limits the driving electricity supplied to the steering motor based on at least one of a value of the secondary voltage and the electricity supply state of the transformer section indicated by the second signal. Accordingly, driving electricity is stably supplied with the steering motor with a simple configuration even if the input of the first signal is disrupted due to a failure in the in-vehicle network.

Abstract: The electrically-powered steering apparatus obtains a steering torque and a steering angle within an allowable input range of those inputted into a first resolver and a second resolver based on a real zero point ? and further, a steering torque and a steering angle out of the allowable input range of those inputted to the first resolver and the second resolver based on (+) virtual zero point ? and (?) virtual zero point ?, which are set to a different value from the real zero point ?. Consequently, of the steering torques and steering angles inputted to the first resolver and the second resolver, the steering torque and steering angle out of the allowable input range impossible to obtain by the real zero point ? can be obtained based on the (+) virtual zero point ? and the (?) virtual zero point ?.

Abstract: An electric power steering apparatus transmits a driving force of an electric motor to a steering mechanism for steering assist. The apparatus includes a torque sensor which detects a steering wheel torque; a basic assist characteristic determining section which determines a basic assist characteristic defining a basic characteristic of a motor driving target value for the steering torque; a motor driving target value determining section which determines the motor driving target value for the steering torque in accordance with a modified assist characteristic prepared by shifting the basic assist characteristic along a steering torque coordinate axis; a shift amount determining section which determines the amount of the shift from the basic assist characteristic to the modified assist characteristic on the basis of the steering torque; and a motor driving section which drives the electric motor on the basis of the motor driving target value.

Abstract: An electric power steering apparatus includes a booster circuit and a microcomputer. The booster circuit includes a booster coil, a first FET, and a second FET. The booster coil is connected to the first FET, which is grounded. A node a between the booster coil and the first FET is connected to the second FET, which is connected to a drive circuit. The microcomputer drives the first and second FETs such that the first and second FETs are selectively turned on and off, thereby controlling an output voltage of the booster circuit. When application of assisting force to a steering system is stopped, the microcomputer holds the second FETs on until the output voltage of the booster circuit becomes equal to a predetermined voltage.

Abstract: A microcomputer includes a rotation angular velocity computation section, a feedback gain determination section, and a dead time compensation amount determination section. The rotation angular velocity determination section computes the rotation angular velocity of a brushless motor. Based on the rotation angular velocity, the feedback gain determination section determines feedback gains. The dead time compensation amount determination section determines a dead time compensation amount. The greater the absolute value of the rotation angular velocity, that is, the higher the rotation speed of the brushless motor, the greater the feedback gains determined by the feedback gain determination section become, and the higher the responsivity of the feedback gains becomes. The greater the absolute value of the rotation angular velocity, the smaller the dead time compensation amount determined by the dead time compensation amount determination section becomes.

Abstract: The invention provides an electric power steering apparatus which can detect a ground fault of an angular resolver without fault. Values of a first resistance (R1), a second resistance (R2), a third resistance (R3) and a fourth resistance (R4) are set such that a difference between a minimum output potential (Vout Min) of a first differential amplifier (OP1) at a time when an angular resolver is not in a ground fault which may be generated on the basis of a dispersion of the first resistance (R1), the second resistance (R2), the third resistance (R3) and the fourth resistance (R4), and a direct-current resistance component (Rdc) of the angular resolver, and a maximum potential (Vout Max) at a time when the angular resolver is in the ground fault becomes equal to or more than a predetermined margin for preventing an erroneous ground fault detection in a CPU (62) side.

Abstract: A microcomputer includes an actual DUTY value detection section that detects an actual DUTY value ?x by measuring the ratio of time in which an output voltage of each phase becomes a power supply voltage in a cycle of a triangular wave. A dead time compensation computation section subtracts the actual DUTY value ?x from a DUTY instruction value ?x before correction, thereby computing a difference value ?x. Subsequently, the dead time compensation computation section adds the difference value ?x to dead time compensation amounts ?xp, ?xm, which have been used for correcting the DUTY instruction value ?x, thereby determining new dead time compensation amounts ?xp? and ?xm?. The dead time compensation amounts ?xp, ?xm stored in a memory are renewed with the new dead time compensation amounts ?xp?, ?xm?.

Abstract: The atmosphere temperature calculator calculates an estimated atmosphere temperature value by subtracting a temperature rise amount of a temperature sensor which is calculated based on a motor drive detected current value from a detected temperature value of the temperature sensor. The overheating prevention calculator calculates estimated temperature values of a plurality of protection objects to be protected from overheating based on the estimated atmosphere temperature value and the motor drive detected current value and determines an upper limit of target current of driving a motor based on such estimated temperature values. The temperature compensation calculator calculates a temperature compensation current value to be added to a target current value in order to compensate a temperature characteristic of a predetermined portion based on the estimated atmosphere temperature value.

Abstract: The invention provides an electric power steering apparatus in which a dead zone is not generated even at a low duty ratio while slow starting a switching element. When a duty ratio of a PWM control becomes more than a preset value (NO in S14), a switching cycle is set to a predetermined value (a fixed value) (S20). When the duty ratio becomes equal to or less than the preset value (Yes in S14), the switching cycle is made longer than the predetermined value (S16). It is possible to securely apply a current to a motor and it is possible to prevent a dead zone from being generated, by elongating the switching cycle even in a low duty ratio while slow starting an FET and preventing a noise from being generated.

Abstract: In a torque sensor, a first detection tube (13) made from magnetic material covers a cylindrical magnetic leak prevention member (12) that is made from nonmagnetic material and covers a first shaft (3) made from magnetic material. Magnetic resistance to magnetic flux, which passes through one end of the first detection tube (13) and one end of a second detection tube (14) that is made from magnetic material and rotates together with a second shaft (4), changes according to elastic relative rotation of the two shafts (3, 4) corresponding to transmitted torque, by providing a plurality of teeth (13a, 14a) along the circumferential direction at the one end of each detection tube (13, 14). The first shaft (3) and the first detection tube (13) are integrated with the magnetic leak prevention member (12) so that they can rotate together, by being inserted in a mold for forming the magnetic leak prevention member (12) before the synthetic resin material is poured into the mold.

Abstract: A curved leaf spring which is a first urging member surrounds an outer wheel of a second bearing, and urges, through the second bearing, a second end of a worm shaft in a direction in which the distance between the center of the worm shaft and the center of a worm wheel is shortened. A second urging member includes an annular support member received by an end surface of the outer wheel and a plurality of elastic pins extending in a direction in parallel with the axial direction of a support member. The elastic pins have fixed ends fixed to the support member and free ends that come into elastic contact with an end wall of a housing.

Abstract: A controller for a brushless motor that suppresses torque reduction resulting from the influence of motor inductance and suppresses the generation of invalid current. A phase advancing angle calculator calculates a delay angle of phases of phase currents with respect to the phases of the phase voltage command and a phase advancing angle corresponding to the delay angle based on the function of the angular velocity and the motor inductance (and armature winding resistance) of the brushless motor. An adder adds the phase advancing angle to the rotation angle provided from the rotation angle calculator to generate the corrected rotation angle. The adder further provides the corrected rotation angle to a two-phase/three-phase converter.

Abstract: An angle detection apparatus includes a resolver having a rotor core and a stator core, and a computation unit having a multiple rotation amount computation, accumulation and an abnormality determination sections. The rotor core moves along the axial direction of a steering shaft in response to rotation of the steering shaft. Based on a change of a transformation ratio of the resolver caused by a change of the relative positions of the rotor core and the stator core along the axial direction due to movement of the rotor core, the multiple rotation amount computation section computes a first multiple rotation amount N of the steering shaft. The multiple rotation amount accumulation section detects the switchover point of the absolute angle .theta.0 when the steering shaft is rotated a single rotation, and computes a second multiple rotation amount N? by accumulating the number of detection of the switchover point.

Abstract: A motor control device is provided with a neutral point shift section. The neutral point shift section shifts a neutral point (command neutral point) of phase voltage commands so that the values of the phase voltage commands after the shifting of the neutral point come within the amplitude of a triangular wave (triangular wave signal), and inputs the phase voltage commands with the neutral point having been shifted, to a control signal output section. Thus, the motor control device is enabled to heighten the output voltage without bringing about increase in manufacturing cost and substantial delay in calculation interval.