Module 6 ECS (electronic control suspension) eng

Hệ thống treo điều khiển điện tử (ECS) được phát triển để mang đến sự thoải mái khi lái xe phù hợp và ổn định lái xe trong các điều kiện lái xe khác nhau. Một hệ thống treo được thiết kế để hỗ trợ trọng lượng xe để cải thiện thoải mái đi xe và ổn định lái xe. Nó cải thiện lực kéo bề mặt lốp xe của một chiếc xe đang được điều khiển và hấp thụ rung động cơ thể xe và tác động do tiếp xúc bề mặt. Tuy nhiên, hệ thống treo không thể đảm bảo cả sự thoải mái khi lái xe và sự ổn định lái xe vì lực giảm xóc liên tục và giảm chấn của lò xo được đưa ra trong một khung cảnh nhất định. Ví dụ, một hằng số đàn hồi thấp hơn được sử dụng cho một chuyến đi mượt mà và thoải mái hơn, nhưng điều này dẫn đến sự chuyển động lò xo tăng từ các yếu tố môi trường cũng như sự chuyển động của chính chiếc xe. Vì lý do này, độ ổn định lái của hằng số đàn hồi thấp hơn được giảm tốc độ cao và bề mặt không đồng đều. ECS giải quyết vấn đề này bằng cách giảm lực giảm chấn của hệ thống treo cho sự thoải mái khi lái xe trong điều kiện lái xe bình thường và tăng lực giảm chấn khi lái xe trên các bề mặt không đồng đều và ở tốc độ cao để ổn định lái xe. Nói ngắn gọn, ECS thay đổi không đổi độ đàn hồi, giảm chấn và áp suất mạch giảm sốc bằng nệm khí theo tốc độ lái xe và điều kiện đường để kiểm soát chiều cao vị trí của xe để cải thiện độ ổn định lái xe và thoải mái khi lái xe.

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Suspension)

LESSON

6.1 Overview 145

6.1.1 Introduction 145

6.1.2 History 146

6.2 Electronic Control Suspension 147

6.2.1 Overview 147

6.2.2 Layout 148

6.2.3 Components 149

6.2.4 Control 152

6.3 Electronic Control Air Suspension 155

6.3.1 Overview 155

6.3.2 Layout 156

6.3.3 Components 157

6.3.4 Control 162

6.4 Maintenance (for ECAS) 167

6.4.1 Cautionary Measures for Handling Different Parts 167

6.4.2 Air Filling 169

6.4.3 Maintenance Measures by Case 171

6.4.4 Cautionary Measures for Lift-up (Iinitialized Vehicles) 172

6.4.5 Cautionary Measures for Towing 173

[Learning Objective]

▪ Describe the history of ECS and different types of control

▪ Describe the system layout and list the locations, mechanisms and functions of components

▪ Create a pneumatic circuit for vehicle height control by ECAS

▪ Take necessary actions after a part change and list the cautionary measures required for

maintenance

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Electronic Control Suspension (ECS) was developed to provide consistent ride comfort and driving stability

in various driving conditions

A suspension system is designed to support vehicle weight for improved ride comfort and driving stability

It improves the tire-surface traction of a vehicle being driven and absorbs vehicle body vibration and impactcaused by surface contact

However, suspension systems cannot guarantee both ride comfort and driving stability as their springconstant and shock absorber damping force are given a certain setting For example, a lower springconstant is used for a smoother and more comfortable ride, but this results in increased spring movementfrom environmental elements as well as the movement of the vehicle itself For this reason, a lower springconstant's driving stability is reduced by high speeds and uneven surfaces

ECS addresses this issue by reducing a suspension's damping force for ride comfort in normal drivingconditions and increasing the damping force when driving on uneven surfaces and at high speeds fordriving stability In short, ECS varies spring constant, shock absorber damping force and air spring circuitpressure according to driving speeds and road conditions to control vehicle height/position for improveddriving stability and ride comfort

Conventional Suspension System

Cannot provide both ride comfort and

driving stability

ECS (Electric Control Suspension)

Controlled to suit different driving conditions forboth ride comfort and driving stability

ECAS controls damping force and vehicle height, and is generally found in luxury passenger vehicles Itscomponents include a variable damper, for damping force control, and a length-adjustable air spring Theair spring ensures driving stability by keeping the position of an accelerating, braking or cornering vehiclehorizontal High-frequency vibrations that coil springs cannot absorb are absorbed by air springs, whichresults in ride comfort As such, vehicle-height-controlling suspension systems are ideal as they provideboth ride comfort and driving stability.

1) Continuously Variable Damper

1 Functions and Roles

Made up of an integrated shock absorber and solenoid valve, a continuously variable damper isinstalled on each of a vehicle's four wheels Solenoid valve control allows damping force (force thattries to stop spring movement against the shock absorber) to be continuously controlled

2 Mechanism

ECS ECU controls the damping force variable solenoid valve according to driving conditions Currentcontrol moves the spool valve inside the solenoid valve to change the flow and continuously switchthe damping force of the continuously variable damper

An electrical current between 0.3-1.3 A is needed for the external solenoid valve Current adjustment

to 0.3A moves the spool valve up and constricts the orifice, slowing down oil flow and increasingdamping force; this "hardens" the ride feel (hard mode) Conversely, current adjustment to 1.3A movesthe spool valve down and expands the orifice, speeding up oil flow and decreasing damping force; this

"softens" the ride feel (soft mode)

3) Wheel G Sensor

Installed under the continuously variable damper of the front wheels, the wheel G sensor detects tireoperation and continuously variable damper speed in harsh conditions mode It can detect the surfacequality of unpaved roads and the rough conditions of uneven surfaces Compared to conventional versions,the damper is precisely controlled to improve ride comfort as the vehicle passes over uneven road surfaces

4) SAS (Steering Angle Sensor)

The steering angle sensor detects steering speed and angle to detect vehicle body roll It provides theinput signals required for anti-roll control This sensor is installed inside the MDPS assembly and receivessignals through CAN communication with MDPS

5) WSS (Wheel Speed Sensor)

The wheel speed sensor detects wheel speed to provide the input signals required for handling, anti-squatand high-speed stability control It uses a hall element and is installed on the tone wheel, and receivessignals through CAN communication with ECS/ABS

Wheel G Sensor SAS (Steering Angle Sensor) WSS (Wheel Speed

Sensor)

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6) ECS Mode Switch

Figure 6-1 ECS Switch

The ECS mode switch (self-return-type) is used by the driver to switch between sport mode and normalmode to suit driving conditions A single press enables sport mode and another single press enables automode

Sport mode puts CDC in "hard mode" to improve driving stability at the expense of ride comfort for drivingthrough multiple bends and sporty driving

7) ECS ECU

ECS ECU is installed on the right of the center of the cowl crossbar With vehicle driving/position datareceived from various sensors, ECS ECU performs real-time solenoid valve control for adjustment of thedamping force of the variable dampers installed a vehicle's four wheels

ESC ECU operation is controlled by the actuator relay located at the center of the dash panel Uponactivation, the actuator relay supplies currents to the damping force variable solenoid vagve through theECU's internal circuit If engine RPM falls below 500 while driving, ECU stops actuator relay operation

8) ECS Lamp

Located on the cluster, the ECS indicator switches on when sport mode is selected, blinks when ECS isfaulty and switches off in normal mode Contacts are controlled according to ECU switch signals or in theevent of ECU trouble

Figure 6-2 ECS Lamp

1) Input & Output Elements

Power-supply to ECS ECU triggers ECU to inspect components and prepare for operation The body

G sensor and wheel G sensor detect vehicle movement and send data to ECU The driver's intentionsare detected through the ECS mode switch, vehicle speed, throttle position sensor, brakes and steeringangle sensor; after required damping force control is calculated, the damping force variable solenoid iscontrolled When sport mode is enabled, the ECS indicator switches on In the event of system trouble,the ECS warning lamp blinks and communication takes place with external diagnostic equipment for troublediagnosis

2) System Control

Ride control logic

(pitch, bounce)

Top/bottom vibrationsuppression whendriving on an inflectedsurface

Body G Sensor (3EA)Wheel G sensor (2EA)ECS mode switch

Anti-roll control logic

Left/right vibrationsuppression duringturns

Steering Angle SensorECS mode switch

Road Detection →Skyhook Control

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Anti-dive control logic

Front/rear vibrationsuppression in braking

Wheel Speed SensorBrake switch

Anti-squat control logic

Front/rear vibrationsuppression in suddenstart-offs

TPS

Speed sensitive

control logic

Improved drivingstability in high-speeddriving

ECS mode switch

Solenoid Control (4EA)

→ Switch to harddamping force

3) Skyhook

The damper is connected to an imaginary atmosphere to minimize body vibration Skyhook control takesplace automatically when pitch, bounce or roll occurs Based on body and wheel acceleration, skyhookimproves ride comfort and driving stability through continuous damping force control

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The following change occurred for further-improved response and driving stability.

▪ 4 Corner

▪ Open Loop

▪ 4 CornerResponse Time

▪ (coil) + air spring

▪ 6-bar internal pressure (slowvehicle height adjustment)

▪ No guide

▪ Individual air spring installation

▪ 10-bar internal pressure (fastvehicle height adjustment)

▪ Aluminum-guide-attachedAir-supply Open Loop System (slow response) Closed Loop System (fast response)Vehicle Height

Adjustment Highway and rough driving function Highway and rough driving function

Spring Shape

ECAS is made up of the following three components.

▪ Buffering unit: Air spring, variable damper (vehicle height/damper damping force adjustment)

▪ Pneumatic unit: Air injection valve, air filter, compressor, valve block, air tube, reservoir tank

(air-supply/discharge)

▪ Control unit: Vehicle height sensor, G sensor, pressure sensor, ECS mode switch, ECS ECU, ECS

lamp (sensor signal processing and vehicle position control)

The pneumatic circuit of the pneumatic unit and buffering unit is a closed one and promotes air-flow forvehicle height control

2 Variable Damper

ECS ECU monitors vehicle movement and adjusts damper damping force to suit the driving conditions

It maintains an optimum vehicle position for given driving conditions for ride comfort, enhanced controland individual-wheel control

Control current volume is 0A-1.6A; when high currents are recognized, the plunger moves to the right

to expand the orifice through which oil passes (soft mode) Conversely, recognition of low currentsmoves the plunger to the left to constrict the orifice (hard mode)

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2) Air Pressure Section

1 Air Filling Valve

A valve for injecting air into air springs Connected to the reservoir tank, the air injection valve injectsair through diagnostic equipment

• Reversing Valve

Installed inside the compressor, a reversing valve converts the flow of the internal valve for air springair supply/discharge

• Relief Pressure Valve

Installed on the compressor, a relief pressure valve is a safety device that discharges air when thecompressor's internal pressure reaches a hazardous level

• Air Dryer

Absorbs moisture in the air to keep the system moisture-free Humidity is discharged along with air

The air ports are made up of a reversing valve, which returns air to the four air springs and compressor,and a port leading to the air filter.

6 Air Filter

Located on the top left of the wheel house to the right of the engine room, the air filter filters the airsucked into the system

3) Control Section

1 Vehicle Height Sensor

Four vehicle height sensors are installed on the vehicle body and lower arm to detect the acceleration

of the top/bottom of the vehicle body The hall IC detects vehicle height change from sensor movementand sends signals to ECS ECU In vehicle height control, the vehicle height sensor is used for vehicleheight measurement; in damping force control, it is used for estimating the relative speed of eachcorner damper

3 Pressure Sensor

Installed on the valve block, a pressure sensor detects pressure in the system When ECS is notoperating, it monitors system pressure for the reservoir tank; when ECS is operating, it monitors systemcircuit pressure for air spring operation

4 ECS Mode Switch

Four vehicle height sensors are installed on the vehicle body and lower arm to detect the height of thevehicle when moving The vehicle body's top/bottom acceleration is sent to ECS ECU as signals fromthe sensor rod for use in vehicle height control

• Vehicle Height Control Switch

The driver can change the vehicle height by selecting high mode or normal mode Low mode is notswitch-selectable and is enabled automatically when the vehicle maintains a speed of 120km/h orhigher for more than 10 seconds

• Damping Force Control Switch

The driver can adjust damping force by selecting sport mode or auto mode

6 ECS Lamp

The ECS indicator is located on the cluster The "High" lamp is switched on when high mode is enabledfor vehicle height control The "Sport" lamp is switched on when sport mode is enabled for dampingforce control

1) Input & Output Elements

ECS ECU detects vehicle movement through the vehicle height sensor, G sensor and pressure sensor,and recognizes the driver's intentions through the ECS mode switch Calculations for vehicle height anddamping force control are made based on data received from ECM, ABS/ESC and MDPS Air flow iscontrolled through the solenoid valve, exhaust valve, reversing valve and compressor relay to increase ordecrease vehicle height Damping force is made hard or soft through the variable damper valve for ridecomfort and driving stability

2) Vehicle Level Control

● Overview

Vehicle height can be controlled while driving or stationary manually or automatically

The driver the can manually control the vehicle height switch to select one of two levels (normal/off-road).Auto mode lets ECU adjust vehicle height to level ideal for given driving conditions Adjustable levelsinclude Normal (design height), Highway (low) and Off-road (high)

Pneumatic control occurs as shown in the diagram below for height height control when certainconditions are met

● Level Operating Modes

Vehicle control takes place in the various operating modes of ECU

• Sleep state

Sleep mode reduces ECU's power consumption Level control is disabled in sleep mode Sleep mode

is exited when ECU detects a ECU wake-up pin or when IGN is switched on After IGN switch-off,ECU enters sleep mode after a set delay time A vehicle left in sleep mode for a prolonged time wakes

up ECU every two, five and ten hours (adjustable) for normal vehicle height maintenance

• Wakening state

The period between IGN switch-off and sleep mode entry is referred to as wakening mode In thismode, vehicle height cannot be manually controlled using HMI and only automatic vehicle heightcontrol takes place

to be under 70; if higher than 70, vehicle height is returned to normal automatically Vehicle height

is automatically lowered when vehicle speed of 120 or higher is maintained for 10 seconds, beforereturning to normal when vehicle speed is maintained at 80 or lower for 5 seconds

3) Damping Control

● Overview

The body of a moving vehicle vibrates constantly due to contact with (uneven) road surfaces, possiblycausing the driver discomfort Damping control prevents this issue through continuous damping forcecontrol through variable dampers for optimum ride comfort and driving stability

● Skyhook

Skyhook control is one of the most effective algorithms for vehicle suspension damping control Fromvirtual coordinates located in the space above a vehicle, the vehicle body's up/down vibration is detectedand skyhook dampers' damping force is increased appropriately to reduce vehicle body vibration

● Ride comfort control

• Anti-squat: Changes all CDC dampers from soft to hard during sudden acceleration, before graduallyreverting to soft mode (check engine torque)

• Anti-Dive: Changes all CDC Dampers from Soft→Hard during sudden braking, and slowly restoresSoft Mode (check brake pressure)

• Anti-Roll: Changes all CDC Dampers from Soft→Hard during hard turn, and slowly restores SoftMode (check Latitudinal-G and steering angle)