Suspension Control System

Through its influence on ride comfort and handling, the suspension is an important system for ensuring driving comfort by providing a sense of stability and reassurance and by being less tiring for the driver. In particular, controlled suspensions provide a high level of both handling and ride comfort. At the same time that greater use is being made of these in small, low-cost vehicles, mainly in the form of semi-active suspension, progress also continues on improving performance through integrated control and cooperative operation with other chassis control systems.

Shock Absorber

Frequency variable damping force provides superior ride and handling
1) Generate Low D/F at small amplitude and High Frequency Input condition
=> Reduce harshness and improve secondary ride
2) Hold High D/F at Lower Frequency Input
=> Improve roll, flatness and handling and for primary ride
Compact packaging design for frequency response feature enables to wide range application
Smooth D/F Transition characteristic provides comfortable ride with less noise

High quality and performance Shock Absorber with wide size selections for the flexible adoption to the various vehicle sizes and the requirements .They comes in different category like Non Gas Pressurized Type, Gas pressurized Type, High Functional Type base on different types like Conventional, Conventional & With Spring-Seat Type , Damping force Adjustable, Self Leveling and Air Suspension.

Image:e-ACT

page top

Suspension Strut

Brake Master Cylinder

Available both non gas and gas pressurized types
Applied high performance oil seal, low friction dry metal bearing and PTFE banded piston to all struts
Full clamped deflection disk type valves on piston and bottom valves for the minimizing noise potential
Optional full displacement type piston valve with gas pressurized for the outstanding tunability and damping force response brought by large compression effective area

High quality and performance Suspension Strut with wide size selections for the flexible adoption to the various vehicle sizes and the requirements .They comes in different category like Non Gas Pressurized Type, Gas pressurized Type, High Functional Type base on different types like Conventional, Conventional & With Spring-Seat Type , Damping force Adjustable, Self Leveling and Air Suspension.

Image:e-ACT

page top

Hydraulic Cylinder

High pressure low friction Rod seal
Internal low leak Piston seal
Operating pressure 2MPa~15MPa
Structure using a cast iron casing

Image:e-ACT

Hitachi Automotive Systems Americas, Inc.’s Hydraulic Cylinder for Roll Control realized low friction with little inside leak by an unique seal structure. Twin tube structure using a cast iron casing allows sufficient cylinder stroke as well as closer fluid ports layout that eases vehicle application.

Semi-active Suspension System

Characteristics

This system includes a sensor that detects bumps on the road and movements of the vehicle, and a controller that control the damper on each wheel. The semi-active suspension can respond to even slight variations in road surface and to cornering. Use of semi-active suspension, in particular, is extending beyond top-end models to also include small, low-cost vehicles, with performance improvements being achieved through integrated control in cooperation with other chassis control systems. The system obtains a high level ride & handling performance with low energy consumption through real time damping control. It is part of Chassis Control system which is also called Vertical Direction Control.

Features & Benefits

Active variable damping force (for superior “Ride and Handling”) is provided by;
(1) Greater range of damping authority and tunability due to the Triple Tube Side Mounted Solenoid Valve
Body : pressure balanced linear solenoid and Dead length radial package space due to the Internal
Integrated Solenoid.
(2) Hitachi Automotive Systems Americas, Inc.’s unique nonlinear adaptive control logic.
Unique noise cancelling device is available for chuckle/rattle noise issues.
(1) Reduced Piston Rod Acceleration while maintaining Wide Damping Force Variable Range
Bi-Linear Optimal Control (BLQ) based ride control logic reduces body vertical acceleration and jerking movement
New handling control logic improves roll feeling in a normal cornering and vehicle stability in a critical region
Decrease abnormal body movement body jerking movement by smooth control command with Bi-Linear Optimal Control (BLQ)
Balance the roll feeling in a normal region with vehicle stability in a critical region by using a gain scheduled controller
Improvement of body acceleration and jerking movement with BLQ control
Improvement of Roll Feeling by nose-diving motion
Improvement of vehicle stability in limit region

Supporting Technology

Damping Force Valve Design
(1) Computational Fluid Dynamics for Optimum Damping Force Resurge
(2) Calculate Distribution of Velocity for Optimum Valve Design
(2) Calculate Distribution of Velocity for Optimum Valve Design
(3) Evaluate Dynamic Behavior of Valve Unit by Bilateral Oil Flow Bench
(4) Wide D/F Variable Range and Noise Reduction by CAE-Analysis and Prototype Evaluation
Control Logic
(1) Apply Nonlinear Adaptive Control Logics with Observer
(2) Realize High Quality and Performance Control System by MCD
(3) Shorten Development Lead-time by Optimum Design Method

Structure of semi-active suspension system

Image:e-ACT

page top

Air Suspension Compressor

Air Suspension Compressor for Air Suspension

Improve for heat resistance
Reduced motor temperature
Improve Durability life for Delivery valve
Improve for Compressor adiabatic efficiency (Low current)
Improve Motor efficiency
Reduced Volume efficiency
Keep the same Flow Rate
Small and lightweight compressor with integrated dehumidification dryer and exhaust valve
Wide product lineup
Low noise type to high efficiency type
Waterproof structure
Excellent flexibility for various in-vehicle locations
Oil and maintenance free

This air compressor is constructed to maintain the air pressure in the air springs, with OE-like function and reliability. Better control of proper damping force and further development of height adjusting technology keeps Hitachi Automotive Systems Americas, Inc. ahead of vehicle suspension technology. The air suspension compressor fills the air bags with pressurized air, raising the chassis depending on the load carried on your vehicle. It adjusts the vehicle's height to improve the ride comfort, road handling, and stability. It is designed to effectively provide air pressure sufficient to ensure superior ride quality.