Steering System

Electronically controlled steering was initially limited to speed sensitive power steering systems. There are two types of power steering systems: electric power steering systems and hydraulic power steering systems. Currently hydraulic power steering systems are widely used, but electric power steering systems are rapidly coming into use, primarily in small passenger vehicles. EPS (electric power steering system) designed for small passenger vehicles that are currently mass produced. It conveys the motor torque to the steering gear from the pinion shaft through the reduction gear mechanism.

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Electric Power Steering Systems

Features & Benefits

The pinion assist type electric power steering systems Hitachi Automotive Systems Americas, Inc. is currently mass-producing consist of:

High output and high-performance steering rack thrust up to 15 KN
Increasingly advanced components
Electronically-controlled and electrically-driven
High precision and highly reliable mechnics
A torque sensor that detects steering force
An electronic High precision and highly reliable mechanics
A torque sensor that detects steering forcesist force to a pinion shaft through a reduction gear mechanism
A rack and pinion type steering gear

Image:EPS

The electronic control unit controls speed sensitive power steering systems by processing signals indicating the vehicle speed and the rotation of the engine. In addition, the torque limiter is positioned between the plastic gear in the reduction gear mechanism and the pinion shaft, and this protects the plastic gear from road surface pressure.

Belt Drive EPS System (BEPS)

Characteristics

Hitachi Automotive Systems Americas, Inc. Belt Drive Electric Power Steering System with enhanced steering feel and ISO 26262 ASIL-D compliant design.

Features & Benefits

Advanced safety with Limp Home and ISO 26262 ASIL-D compliant design
High reliability due to elimination of mechanical relays & ribbon cables
Enhanced steering feel is achieved by high accuracy rack, ball screw, pinion gear and ball screw grade control, all made in-house by Hitachi Automotive Systems Americas, Inc.
Full development capability from control logic to system development.
Torque Sensor: Non-contact Hall effect
Redundant
Digital communication
Absolute Steering Angle Sensor: Twin Gear with non-contact GMR plus Motor Position Sensor
Redundant and Digital communication
Limp Home function is realized by the addition of redundant sensors

Image:EPS

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VDP and e-VDP for power steering

Characteristics

VDP and e-VDP for power steering to realize fuel economy improvement .This pump type has been developed to assist the automotive industry in reducing the fuel consumption and CO2 emissions particularly of upper mid-size and luxury cars to Large Trucks. Variable Displacement Pump makes a significant contribution to reducing the energy consumption of hydraulic steering systems and is characterized by a variable flow rate. The adjustable curve ring enables the control of the geometric flow rate depending on the speed. So the pump supplies always based on the required characteristic curve of the supply rate.

Features & Benefits

Fuel consumption can be improved
System oil temperature can be reduced allowing the cooling pipe to be simplified or eliminated
Discharge flow rate can be electronically controlled corresponding to vehicle parameters, leading to optimized steering effort (e-VDP)
Simple replacement of conventional pump due to standardized fixing
Reduced power consumption
Reduction of CO2 emissions

Image:VDP-E-VDP

VDP is an oil pump for power steering used to achieve energy savings by eliminating a pump’s excessive operation as well as reducing driving torque by variably-controlling the displacement automatically corresponding to the pump speed.
e-VDP achieves even greater energy saving by electronically-controlling the discharge flow rate in accordance with certain vehicle parameters (vehicle speed, steering angle speed, etc.) in order to improve fuel economy and reduce CO2 emission.