Electric power steering device

Abstract

In an electric power steering apparatus that generates an auxiliary steering torque by a brushless motor in response to a steering torque applied on a steering wheel and transmits it to an output shaft of a steering mechanism while reducing it by means of a reduction gear, the apparatus comprises a rotor ( 10 ) to which a cylindrical permanent magnet for rotational driving ( 12 ) and a member to be detected ( 13 ) for detection of a rotational angle of the rotor are attached and a cylindrical stator ( 30 ) opposed to the rotor in which a laminated core ( 16 ) on which a coil is wound, detection means ( 17 ) for detecting the rotational angle of the rotor by the member to be detected and a terminal ( 19 ) for providing connection to the coil are integrally formed by resin molding. At least one bearing ( 8, 9 ) for rotatably supporting the rotor is disposed radially inside the stator and between the permanent magnet for rotational driving and the member to be detected.

Description

technical field [0001] The present invention relates to an electric power steering device for a vehicle and a brushless motor suitable for the device. Background technique [0002] In the known vehicle electric steering device, the rotational output of the motor providing auxiliary steering torque is transmitted to the output shaft of the steering device through a gear device to increase the steering force acting on the steering wheel during the steering operation of the steering wheel. In such an electric power steering device, power is transmitted to an output shaft, while the power transmission mechanism provided in the housing reduces the rotational speed of the motor. [0003] The mainstream motors used in this type of electric power steering are usually brushed motors. However, in recent years, this mainstream motor has moved to brushless motors to improve reliability and further improve efficiency. [0004] Figure 16 An electric power steering using a brushless mot...

AI Technical Summary

Problems solved by technology

[0023] In a bearing support structure in which a rotor is provided with a bearing cavity integrally formed by resin molding, it is generally difficult due to state changes during molding, shrinkage ratio depending on the direction of resin molding, welding, or other reasons. Improve the accuracy of the bearing cavity

If the accuracy of the bearing cavity is low or its coaxiality with the inner periphery of the stator is low, the coaxiality between the cylindrical stator and the cylindrical rotor inserted into it for rotation will be reduced

Therefore, it will increase the pulsating torque, increase the friction torque and increase the noise of the motor

Increased pulsating torque is transmitted to the driver's hands, directly making him / her uncomfortable, while increased frictional torque not only loses motor power, but also reduces responsiveness to motor control signals

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