Daewoo Nexia

Since 1994 of release

Repair and car operation

17.35. Antiblocking system of brakes

THE GENERAL DATA

The modulator of a forward wheel – the basic mode of braking

AND. THE MODULATOR INPUT (FROM THE MAIN BRAKE CYLINDER) CENTURY THE MODULATOR EXIT (TO THE WHEEL CYLINDER) 501. NORMALLY OPENED ЭМК (IN OPEN POSITION) 502. THE RETURN BALL VALVE (IN OPEN POSITION) 503. THE PISTON 516. THE CASE OF THE MODULATOR WITH THE ELECTROMECHANICAL DRIVE

Spring brake

505. THE SPRING LOCK RING 506. THE GEAR WHEEL THE LEADER 507. THE GEAR WHEEL CAM 508. THE BRAKE SPRING 509. LEADING KULACHKOVAJA МУФТА 510. THE ELECTRIC MOTOR SHAFT 511. THE ELECTRIC MOTOR CASE

The modulator of a forward wheel – braking at work АБС

AND. THE MODULATOR INPUT (FROM THE MAIN BRAKE CYLINDER) CENTURY THE MODULATOR EXIT (TO THE WHEEL CYLINDER) 501. NORMALLY OPENED ЭМК (IN THE CLOSED POSITION) 502. THE RETURN BALL VALVE (IN THE CLOSED POSITION) 503. THE PISTON 516. THE CASE OF THE MODULATOR WITH THE ELECTROMECHANICAL DRIVE

The modulator of back wheels – braking at work АБС

AND. THE MODULATOR INPUT (FROM THE MAIN BRAKE CYLINDER) CENTURY THE MODULATOR EXIT (TO THE WHEEL CYLINDER) 502. THE RETURN BALL VALVE (IN THE CLOSED POSITION) 503. THE PISTON 516. THE CASE OF THE MODULATOR WITH THE ELECTROMECHANICAL DRIVE

The list of reductions

АБС	Antiblocking system
+	Pressure of the storage battery
КН	Malfunction code
ТECU	The electronic block of management of braking
ЭМК	The electromagnetic valve

At emergency braking when blocking of wheels is the most probable, the electronic block of management of braking (ТECU) carries out automatic control of pressure of a brake liquid in a drive of each forward wheel (individually) and in a drive of back wheels (synchronously). ТECU provides braking of wheels without blocking and by that reduces risk of drift of the car, improves stability and controllability of the car at emergency braking. It is necessary to notice that system ABS VI cannot increase pressure of a brake liquid in wheel cylinders in comparison with pressure in the main brake cylinder which completely depends on effort to a brake pedal. АБС functions in a range of speeds from 5 km/h till the maximum speed of the car.

At office braking in usual road conditions the Brake system works in the basic mode: by pressing a brake pedal the vacuum amplifier and pistons of the main brake cylinder joins force a brake liquid in wheel cylinders. Each of two channels ABS serving forward wheels, includes the separate modulator with an electromechanical drive. The modulator consists of the case in which hydraulic channels, the electromagnetic valve (ЭМК), the return ball valve, the piston with a ball nut and the running screw are executed. The electromechanical drive consists of the electric motor, a spring brake and шестеренной transfers. In the basic mode of braking the piston is in extreme top position. Moving of the piston to this position is provided with an electromechanical drive with the help шариковинтовой transfers. For piston fixing the spring brake serves in the top position. The brake consists of a spiral spring with two pads unbent inside which is inserted with a small backlash in cylindrical расточку electric motor cases. The spring is put on a shaft of the engine and is between the leader кулачковой муфтой and a gear wheel with face кулачковой муфтой. Cams of the leader муфты and gear wheels are hooked with corresponding pads of a spring (fig. the Spring brake see). In the basic mode of braking on the piston from outside a brake liquid the force directed downwards operates. This force will be transformed шариковинтовым by the mechanism to a twisting moment which is transferred to a gear wheel of the engine and a spring of a brake and operates counter-clockwise. The twisting moment causes закрутку and radial expansion of the spring, which coils rest against a wall расточки and brake a gear wheel. The piston, being in the top position, opens the return ball valve. At braking the brake liquid passes in the basic mode to the wheel cylinder on two channels: Through the return valve opened by the piston also are normally opened and ЭМК. It provides possibility of braking of the car at refusal АБС (the piston does not come back in the top position) or at обесточивании systems (fig. the Modulator of a forward wheel – the basic mode of braking see).

The modulator of back wheels works similarly except for following features. Both back wheels cope synchronously and, besides, in a modulator design is absent ЭМК. Synchronous management of braking of back wheels has allowed to apply one electromechanical drive instead of two and to simplify design АБС. The principle is applied To management of braking of back wheels "Select Low" which provides simultaneous растормаживание both back wheels at the beginning of blocking of any of them. This principle provides good cross-section stability of the car at braking. Absence in the modulator of back wheels ЭМК is caused by that the contribution of back wheels to efficiency of braking is rather insignificant and at refusal АБС the car can be braked with the set delay by one forward wheels. At refusal АБС which puts out of action brake contours of back wheels, ТECU establishes a corresponding code of malfunction and includes both signalling devices: Yellow "ABS" and red "BRAKE".

АБС starts to work only at the included stoplight after microprocessor TEBU will find out the blocking beginning at least one of car wheels. In this case ТECU carries out by means of the modulator regulation of pressure of a brake liquid in a brake contour соответ ствующего wheels (or wheels) for the purpose of prevention of its blocking and preservation of stability and controllability of the car. Cycles of regulation of pressure repeat some times for a second. It is necessary to notice that system ABS VI cannot increase pressure of a brake liquid in wheel cylinders in comparison with pressure in the main brake cylinder which completely depends on effort to a brake pedal. As a result of application АБС brake efficiency, and also course controllability and контролируемость braking in various road conditions improves. At the beginning of blocking of wheels ТECU operates inclusion of electric motors and ЭМК three modulators. At inclusion of the modulator of forward wheel ЭМК at the command of ТECU closes section of one through passage of channels, I connect щих the wheel brake cylinder to the main cylinder (fig. the Modulator of a forward wheel – braking at work АБС see). Then ТECU regulates pressure in the isolated contour of a wheel, operating the electric motor of a drive of the piston of the modulator. At electric motor inclusion the brake spring twists with simultaneous radial compression of coils and releases a leading gear wheel (fig. the Spring brake see). At piston lowering the return valve is closed, completely disconnecting the wheel brake cylinder from the main cylinder. Pressure in the wheel cylinder depends on volume надпоршневой modulator cavities. Pressure reduction in a brake contour of a wheel is reached by lowering of the piston of the modulator. For increase in pressure of a brake liquid the piston rises upwards. Piston movement is carried out шариковинтовой by transfer and an electromechanical drive of the modulator. If the wheel has started to be blocked on a slippery surface (for example, on ice) at small pressure in a brake drive, and then in a phase затормаживания АБС this wheel has got on a site of a surface of road with high factor of coupling, the modulator piston will move to extreme top position and will open the return valve. Thus pressure in the wheel cylinder will be defined by pressure in the main brake cylinder and effort to a brake pedal. The piston will remain in the top position until pressure of a brake liquid does not become sufficient for blocking of a wheel and АБС will not begin a new cycle of regulation. The pressure maximum level in the wheel cylinder in the course of work АБС is limited by pressure size in the main brake cylinder. If in the course of car braking at working АБС the driver reduces effort to a brake pedal, the return valve and a part of a liquid from the wheel cylinder will open will flow in the main brake cylinder. At switching-off АБС the modulator piston comes back in the top position and opens ЭМК (on modulators of forward wheels). After that the Brake system continues to work in the basic mode. The modulator of back wheels at inclusion АБС works similarly except for absent ЭМК. Synchronous movings of pistons in the course of regulation of pressure of a brake liquid are carried out by one electromechanical drive and шариковинтовой transfer. In working cylinders of back wheels it is supported about identical pressure of a brake liquid.

At ignition inclusion the signalling device "ABS" which dies away in 3 seconds lights up. АБС it is automatically resulted in a ready state on reaching speed of the car of 8 km/h. Thus pistons move to extreme top position. Moving of pistons and work of electromechanical drives of modulators can be accompanied by small noise. If the driver presses at this time a brake pedal, it can feel a pedal little push. Thus process of reduction АБС in a ready state will be interrupted.

The standard Brake system is equipped by one red signalling device "BRAKE". In АБС it is used two signalling devices: red "BRAKE" and yellow "ABS".