11.1. General information and security measures
General information
Basic brake system
On the KIA Sportage cars the standard basic double-circuit hydraulic brake system with vacuum strengthening is used. At refusal of any of contours (for example as a result of sealing violation) the second continues to function in the normal mode, providing adequate braking of the vehicle. Forward wheels are equipped with brake mechanisms with the ventilated disks, back - drum mechanisms. In addition the proportional valve regulator of pressure providing dynamic correction of effort of braking of back wheels according to change of load of a back axis of the car is built in a contour of the drive of back brake mechanisms. The lever parking brake has the mechanical hummock drive connected to brake mechanisms of back wheels of the car.
Scheme of the organization of the basic brake system of the KIA Sportage cars
Liquid pressure in both contours is created by the main brake cylinder (MBC) having a tandem design. Activation of GTTs happens when squeezing a pedal of a foot brake. As a result of increase in hydraulic pressure in working contours of the brake system pistons of wheel cylinders are squeezed out of cylinders, providing pressing of frictional blocks / boots to brake disks/workers to the surfaces of reels of wheel assemblies.
The tank with brake fluid is fixed on the main thing brake cylinder (MTBC) and hydraulic a path of the brake system supplies with a working body all.
On petrol models the brake amplifier accumulates a part of the depression created in the inlet pipeline of the engine. On diesel models, in view of lack of such source of depression, the special vacuum pump is used. In case of need the special valve provides connection of the relevant source of depression, providing thereby strengthening of the influence developed by a pedal of a foot brake.
Electronic systems of anti-blocking of brakes (ABS) and distribution of brake forces (EBD)
ABS
On the vehicles equipped with the basic brake system sharp squeezing of a pedal of a foot brake leads to blocking of wheels. At the same time coupling of a protector with a paving is broken and the car can start to skid, losing controllability. The system of anti-blocking of brakes (ABS) prevents premature blocking of wheels, continuously operating the speed of their rotation during braking due to modulations of pressure of hydraulic liquid in each of brake mechanisms.
4-channel MGH 10 ABS with three wheel sensors and the electronic and hydraulic control unit equipped with the electric pump is included in the package of the separate KIA Sportage models.
Scheme of the organization of system of anti-blocking of brakes of the KIA Sportage cars
Forward wheels are equipped with the individual wheel sensors fixed on assemblies of rotary fists, - gear rings (rotors) of sensors are put on stupichny assemblies.
Details of installation of wheel ABS sensors
The back ABS sensor traces the frequency of rotation of a box of differential in a reducer of not cutting back bridge. The sensor is inserted into a case of a reducer and pribolchivatsya to it, - the rotor fastens on a differential box (see the illustration Order of Dismantling of a Reducer of the Back Bridge).
The principle of functioning of ABS is explained on the scheme. The hydromodulator provides three operating modes of ABS: mode of dumping of pressure, mode of deduction of pressure and delivery mode.
Schematic diagram of functioning of ABS
Principle of functioning of ABS
When ABS is not involved, food on electromagnetic valves does not move and they remain in the normal provisions, i.e., inlet valves leave opened the contour connecting GTTs with wheel while final block channels "wheel cylinders - the GTTs tank", preventing thereby dumping of pressure.
As soon as ECU obtains information from any of wheel sensors on the beginning of blocking of the corresponding wheel / wheels, it develops the command for transition of the hydromodulator to the mode of dumping of pressure, for the corresponding electromagnetic valves power supply therefore inlet valves are closed moves, interrupting giving of pressure from GTTs to wheel cylinders, final, on the contrary, open, providing dumping of working pressure in the corresponding contours.
When pressure in working contours falls to critical value, ECU provides switching of the hydromodulator in the deduction mode by removal of food from final valves which come back to normally closed position). At the same time dumping of pressure into the tank of system stops.
When ECU decides that the risk of blocking of wheels is completely prevented, it provides removal of food from all valves of the hydromodulator and the system comes back to the basic delivery mode.
The described cycle is repeated with a frequency of one hundred times a second to a full stop of the car.
At detection of malfunction in an electric or hydraulic part of a control system of functioning the ABS control unit (ECU) of system provides transition it in emergency operation in which food from all valves of the hydromodulator is removed, and in a combination of devices the control lamp of ABS is activated (see the Head Governing bodies and methods of operation). The basic hydraulic brake system at the same time continues to function in the usual mode, providing adequate braking of the car. The driver at the movement on a slippery paving should observe extra care.
EBD system
For prevention of risk of loss of control over management as a result of a drift at premature blocking of back wheels in brake systems of a basic design the special valve regulator regulating pressure in brake mechanisms of back wheels depending on load of a back axis of the car is used. At the same time the less loading, the smaller pressure moves on back wheel cylinders. As a result, during sharp braking when the center of gravity of the car is displaced forward, the risk of blocking of back wheels before lobbies comes down to zero. The main lack of such scheme is the noticeable decrease in efficiency of functioning of back brakes leading to increase in a brake way.
Let's notice also that the form of ideal curve dependence of pressure in contours of back brakes from pressure in lobbies is defined also by identity of structure of material of frictional overlays of brake blocks / boots. Thus, it is not possible to achieve optimum distribution of brake forces mechanically in principle.
One more lack of use of valves regulators is lack of a possibility of the organization of the notification of the driver about their refusal. As a result, the risk of loss of control over driving at sharp braking considerably increases.
Use in standard systems of anti-blocking of brakes of the electronic and hydraulic control unit suggested developers an idea of a possibility of the organization of additional monitoring of the moment of the beginning of blocking of back wheels allowing to make controlled dumping of pressure in a back brake contour with the minimum deviation from curve ideal dependence of distribution of brake forces.
The comparative charts illustrating distinction in the principles of functioning of the valve regulator and the EBD system
At the same time the principle of the organization of management of dumping of pressure in back brake mechanisms is similar to the principle used in ABS: the switching of electromagnetic valves of the hydromodulator which is carried out under control by ECU.
Schematic diagram of functioning of the EBD system
Use of the EBD system allows in an essential measure to reduce length of a brake way and to reduce the effort necessary for squeezing of a pedal of a foot brake. Besides, the effect of decrease in efficiency of functioning of brakes as a result of a warming up of frictional overlays of blocks of forward wheels due to increase in return of back brake mechanisms is compensated.
One more positive EBD property is the possibility of the organization of the warning of the driver of a system exit out of operation, - the standard control lamp of brake system / raising of the parking brake is for this purpose used (see the Head Governing bodies and methods of operation).
As when functioning EBD the electric pump of the hydromodulator functioning of system, in difference from ABS is not used, is not interrupted even at critical undervoltage of the rechargeable battery. The comparative scheme of functioning of the ABS and EBD systems is presented in the table.
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Violation |
System |
Control lamp |
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ABS
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EBD
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ABS
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EBD
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| No | Functions | Functions | Vykl | Vykl |
| Refusal of one of wheel sensors | Does not function | Functions | In C | Vykl |
| Failure of the electric pump | Does not function | Functions | In C | Vykl |
| Critical undervoltage of the battery | Does not function | Functions | In C | Vykl |
| Failure of several sensors, failure of valves, ECU refusal, other refusals | Does not function | Does not function | In C | In C |
Operations procedure at operation of a control lamp of ABS during the movement
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PERFORMANCE ORDER |
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Security measures
- Brake fluid is among highly toxic and chemically aggressive connections and at hit on body panels destroys a paint and varnish covering!
- The brake dust produced in the course of wear of brake shoes may contain unhealthy asbestos of the person, - at all do not inhale it when cleaning brake mechanisms!
- Work with the brake system demands special purity and exact observance of instructions. In the absence of necessary experience it is expedient to address on HUNDRED.
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At movement along wet roads it is necessary to press periodically a brake pedal for removal of moisture from brake disks; |
- In the course of rotation of a wheel moisture under the influence of centrifugal force is dumped from brake disks, but there is a silicone film, rubber attrition products, lubricant and other pollution reducing efficiency of braking!
- After installation of new brake shoes the last have to be earned extra, - try to avoid sharp braking the first 200 km of a run after replacement performance!
- The disk brake mechanisms damaged by corrosion when braking create the effect of jolting which is not disappearing over time, - replace disks!
- Burning of dirt to a surface of brake shoes is led to formation of furrows on a surface of brake disks that leads to decrease in efficiency of braking!