[Problem] An object of the present invention is to miniaturize and integrate plural power semiconductors in an electronic circuit in a low cost without occurrence of a problem of a heat dissipation or the like.

[Means for solving the problem] The present invention is a power semiconductor module that comprises plural arrangements of power semiconductor elements comprising a power semiconductor bare chip which one electrode portion thereof is connected to a metal plate which at least one external connecting terminal is formed and other external connecting terminals which are electrically connected to other electrode portions of the power semiconductor bare chip, and that are contained in a same package, comprises wherein the power semiconductor elements are basically same outline, electrodes of the bare chip of the power semiconductor elements are mutually connected between the power semiconductor elements with a metal connector or a wiring, and the package is a resin mold package that seals the power semiconductor elements with an electrical insulating resin.

[Problem] An object of the present invention is to provide an electric power steering apparatus that constitutes a control system based on a physical model, constitutes a model following control that an output (a distance to a rack end) of a controlled object follows-up to a reference model, suppresses the occurrences of a noisy sound and a shock force at an end hitting without giving any uncomfortable steering feeling to a driver, and is capable of smoothly steering.

[Means for solving the problem] In the electric power steering apparatus that calculates a first current command value based on at least a steering torque and performs an assist-control of a steering system by driving a motor based on the first current command value, the apparatus comprises a configuration of a model following control comprising a feed-back control section including a viscoelastic model as a reference model within a predetermined angle at front of a rack end, wherein the configuration of the model following control comprises a feed-back control section, and the model following control has a noise-reducing function to reduce a noise so as to suppress a rack end hitting.

A motor drive device includes a plurality of control systems that individually supply drive currents to a plurality of coil groups included in a motor. The motor drive device independently sets the current command values for the respective control systems. Based on the set current command values, drive instructions are supplied to drive circuits of inverters with respect to the respective control systems, thereby supplying drive currents from the inverters to the coil groups. The motor drive device detects a failure in any of the inverters and the coil groups with respect to each control system, and stops only the failed control system or causes only the failed control system to fall back. The motor drive device further includes a main computing device, and an auxiliary computing device. Consequently, if the auxiliary computing device is normal even in case the main computing device fails, driving of the motor can be continued using one or some of the control systems.

[Problem]

An object of the present invention is to provide an electric power steering apparatus for calculating a front-wheel estimated steering angle based on right and left front wheel speeds, calculating a rear-wheel estimated steering angle based on right and left rear wheel speeds, calculating a 4-wheel estimated steering angle by using the front-wheel estimated steering angle and the rear-wheel estimated steering angle, and correcting a probability of the 4-wheel estimated steering angle or correcting an output of a control with the 4-wheel estimated steering angle by using the front-wheel estimated steering angle, the rear-wheel estimated steering angle and 4 wheel speeds, thereby preventing an irregular output.

[Means for Solving]

The present invention is an electric power steering apparatus which has a steering torque sensor to detect a steering torque, a current command value calculating section to calculate a current command value based on the steering torque, a motor to apply an assist torque, and a motor driving control section to drive and control the motor, comprises: a control function with an input steering angle; and a steering angle estimating/calculating section to calculate a front-wheel estimated steering angle and a rear-wheel estimated steering angle based on a 4 wheel speeds and calculate a 4-wheel estimated steering angle, wherein the 4-wheel estimated steering angle is used for a steering angle control.

The embodiments relate to a steering system. A steering system according to an embodiment may include a steering assistance device configured to assist a steering device positioned between a steering wheel and a wheel, and a noise reduction device configured to reduce noise of the steering system with the steering assistance device.

A steering axle (20) for a steerable vehicle includes an axle housing (1), a first steering knuckle (4), a second steering knuckle (5), a steering motor (6), and a steering gear (16). The first steering knuckle (4) and the second steering knuckle (5) are mounted so as to be steerable in the axle housing (1). The steering axle (20) has a first flexible drive (21) that connects a first output (12) of the steering gear (16) to the first steering knuckle (4) in terms of drive, and a second flexible drive (22) that connects a second output (13) of the steering gear (16) to the second steering knuckle (5) in terms of drive, so that a rotational speed of the steering motor (6) results in a steering movement of the first steering knuckle (4) and of the second steering knuckle (5). Also disclosed is a corresponding industrial truck.

A steering axle (20) for a steerable vehicle includes an axle housing (1), a first steering knuckle (4), a second steering knuckle (5), a steering motor (6), and a steering gear (16). The first steering knuckle (4) and the second steering knuckle (5) are mounted so as to be steerable in the axle housing (1). The steering axle (20) has a first flexible drive (21) that connects a first output (12) of the steering gear (16) to the first steering knuckle (4) in terms of drive, and a second flexible drive (22) that connects a second output (13) of the steering gear (16) to the second steering knuckle (5) in terms of drive, so that a rotational speed of the steering motor (6) results in a steering movement of the first steering knuckle (4) and of the second steering knuckle (5). Also disclosed is a corresponding industrial truck.

A ball screw mechanism that allows a reduction in contact and friction between a retainer and a nut is provided. In a ball screw mechanism, a nut is threadedly engaged with a screw groove of a rack shaft through balls retained in a retainer groove of a retainer, and an axial force is applied to the rack shaft in accordance with rotation of the nut. The nut includes a uniform diameter portion having a uniform inside diameter and enlarged diameter portions each having an inside diameter larger than that of the uniform diameter portion. The enlarged diameter portions are provided at opposite axial ends of a region on an inner circumferential surface of the nut. The region faces the retainer groove and retainer ends adjoining to opposite axial ends of the retainer groove.

In an electric power steering device which controls an assist motor such that a turning angle of turning wheels approaches a target turning angle set corresponding to steering torque based on an operation of a steering wheel by a driver, pure steering torque is calculated by correcting detection steering torque detected by a torque sensor based on a steering angle detected by a steering angle sensor, and a target turning angle is set based on this pure steering torque. Thereby, influence of moment of inertia and viscous friction of a constituent member on an upstream side of the torque sensor in a steering mechanism, etc. is eliminated, and a correct target turning angle is set. As a result, the turning angle can accurately correspond to the operation of the steering wheel by the driver to attain good drivability.

A damping force control device for controlling damping forces of shock absorbers by a control device, which is configured to to estimate first vertical speeds at the positions of wheels based on the vertical accelerations of a vehicle body at the positions of the wheels, to estimate second vertical speeds of the vehicle body caused by driver's driving operation based on driving operation amount of the driver, to calculate target damping forces by subtracting products of damping coefficients of the ride comfort control and second vertical speeds from the sums of products of the damping coefficients of the ride comfort control and first vertical speeds and products of damping coefficients for controlling posture change of the vehicle body and the second vertical speeds, and to control damping coefficients of the shock absorbers based on the target damping forces.