ECAS (Electronically Control Air Suspension)

INTRODUCTION

Main characteristics:– It keeps chassis height, in motion and when

at the moment of loading and unloading.– It reduces the fuel consumption, because it

minimizes de consumption of air.– Safe and easy handling.CONTROL ALGORITHM

ECAS ( Electronic Control of Air Suspension)

ECAS SYSTEM

Component Location:– 1.      Height sensor (Levelling)– 2.      ECU (Electronic control unit)– 3.      Electro-valve – 4.      Pressure sensor– 5.      RCU (Remote Control Unit)

FUNCTIONS OF ECAS SYSTEM

– Control of normal level: – Height sensors inform regularly of the current level of the chassis. – This value is compared with the one stored in the ECU.– As soon as the difference exceeds the tolerance value, the

electrovalves are activated until the normal level is reached again.– Normal Level I.

– The level described by the manufacturer for its ordinary operations. This level is controlled automatically when the speed exceeds 5 km/h (set value)

– This level determines the degree of driving comfort, safety and structure height.

FUNCTIONS OF SYSTEM ECAS

– Delay in action:– When the vehicle is stopped, the control process is immediate.– When the vehicle is in motion, the ECU starts the control process

60 seconds later. This grants the small and regular oscillations of the chassis (bumps..) not taken into account. The consumption of air is hence reduced to the minimum.

– Normal level II:– It is an optional level that will be automatically controlled by the

ECAS, either depending on the speed of the vehicle ot by means of the switch.

FUNCTIONS OF SYSTEM ECAS

– Adjustment of level using the Remote Control Unit (RCU):– The adjustments with the RCU are only possible when the vehicle is

under a determined speed.– When a determined level has been reached with the RCU , this will

become a temporal normal level.– Two levels may be stored.

– Laterals stabilizers:– In order to reinforce the function of the stabilizing bars of lateral

rolling, the suspension cushions of different sides of the same axle can be controlled individually. This will ensure that the chassis will be placed parallel to axle, even the axle bears more load on one side than the other.

– This option is not often used in trailers with very strong stabilizers.

FUNCTIONS OF SYSTEM ECAS

– Adjustment of height limits:– Once stored the height values (max. and min.), any change of level

requested to the ECU will be stopped when the chassis reaches those levels. The security levels of the suspension of the vehicle will not be exceeded.

– Control of lifting axle:– When the vehicle is stopped, the lifting axle will descend if the

weight of the load on the main axle is exceeded.– The information of the load is sent through the pressure sensor.– The lifting axle will never descend when the vehicle is in motion,

even when the pressure reaches a high level.– Rise of the normal level

– When the lifting axle is up, there can be a rise of the normal level in order to increase the distance between the wheels of this axle and the road. Thus, it avoids the potential wearing of the pneumatics.

FUNCTIONS OF SYSTEM ECAS

– Traction help:– When the lifting axle is down,

if we decrease the pressure of the cushions in this axle, the load will be transferred to the king pin. Thus, we increase the load of the driving axle of the tractor, increasing its traction at the moment of start of the engine.

– An independent switched will be activated.

FUNCTIONS OF SYSTEM ECAS

– Overload protection: – The maximum tolerable pressure on the cushions may be adjusted.

Any overload on the vehicle will cause a reduction of the height level.– The warning lamp will alert the driver about a change of the normal

driving level, and therefore, that the vehicle has been overloaded. – Unloading level:

– It is controlled by means of a switch.– To ease up the unloading procedure, the tank may be leaned ...

FUNCTIONS OF SYSTEM ECAS

– Control of the load sensing valve (LSV):– The pressure on the cushions is used to control the load sensing valve. – In the case of driving with full charge and breakdown in the pneumatic

suspension (cushions without pressure), the braking pressure will not be enough. In order to avoid this, the ECU activates an electrovalve that sends a signal of maximum air pressure to the (LSV) valve

FUNCTIONS OF SYSTEM ECAS

– Compensation of the deflection of the pneumatics.– For vehicles with height

restrictions, small wheels are required and the suspension run is short.

– If the vehicle is fully loaded, the deflection of the pneumatics will be increased, so that the toal height of the vehicle will be reduced.

– ECAS can determine the load of the vehicle, estimate de deflection of the pneumatics and can also correct the total height of the vehicle. Thus, a more distance axle-chassis is obtained.

Height sensors types:

Generation 3 Generation 2

ECAS Components

1. Bobina fija

2. Núcleo desplazable en línea recta

3. Barra reguladora horizontal

4. Cubo

ECAS - 2

ECAS Components

1. Pieza puente metálica

2. Bobina fija

3. Núcleo en el que se ha montado una pletina metálica de forma semilunar.

4. Eje

ECAS - 3

ECAS Components

ECAS Components

• Electrovalves:

ECAS Components

• Remote Control Unit:

FUNCTIONS OF THE WARNING LAMP

SYSTEM ERROR

LAMP ON

When the vehicle is started, the lamp blinks for some seconds. If you switch the ECAS off afterwards it works correctly.

- CHASSIS OUT OF HIS NORMAL LEVEL- AUTOMATIC CONTROL OF THE LIFTING AXLE DISENGAGED BY THE REMORE CONTROL- HELP TO TRACTION ACTIVATED.

LAMP BLINKS

Configurations ECAS

• 1 point control for vehicles with partial air suspension• 2 points control for vehicles with partial air suspensio

n• Electro-pneumatic drawing

• 2 points control for vehicles with full air suspension• 3 points control for vehicles with full air suspension

• Electro-pneumatic drawing

Electrical schemes

• ECAS 24V CAN• ECAS 446 171 ...• ECAS 4x2 KWP

Parameters

• Byte• Hexadecimal format:

0 1 2 3 4 5 6 7 8 9 A B C D E F • Example Actros

• Meaning• Parameters file

Calibration

3.5. Calibrate

- Height sensors calibration

- Display calibration values (Height sensors)

- Pressure sensors calibration

- Display calibration values (Pressure sensors)

ECS Knorr: Components

1. Information lamp bogie axle

2. Display symbol for air suspension

3. Warning lamps 4. Bogie switch and

differential lock switch

5. Remote control box 6. Tridem switch

ECS Knorr: Components

1. Pressure sensor 2. Level sensors 3. Test nipples 4. Solenoid valve assembly, driving axle 5. Solenoid valve assembly, trailing axle 6. Solenoid valve assembly, front axle

.

Levels sensor

Solenoid valve assembly

Click here to see electrically-pneumatic scheme