The hydraulic brake drive of automobiles is hydrostatic, that is, one in which energy is transferred by fluid pressure. The principle of operation of a hydrostatic drive is based on the property of the incompressibility of a fluid at rest, to transfer the pressure created at any point to all other points in a closed volume.

Schematic diagram of the working brake system of a car:
1 - brake disc;
2 - front wheel brake caliper;
3 - front contour;
4 - main brake cylinder;
5 - a reservoir with a sensor for an emergency drop in the level of brake fluid;
6 - vacuum booster;
7 - pusher;
8 - brake pedal;
9 - brake light switch;
10 - brake pads rear wheels;
11 - brake cylinder of the rear wheels;
12 - rear contour;
13 - casing of the rear axle shaft;
14 - load spring;
15 - pressure regulator;
16 - rear cables;
17 - equalizer;
18 - front (central) cable;
19 - parking brake lever;
20 - signaling device for an emergency drop in the level of brake fluid;
21 - parking brake indicator switch;
22 - front wheel brake pad

A schematic diagram of the hydraulic brake drive is shown in the figure. The drive consists of a master brake cylinder, the piston of which is connected to the brake pedal, wheel cylinders of the brake mechanisms of the front and rear wheels, pipelines and hoses connecting all cylinders, control pedals and a drive force amplifier.
Pipelines, internal cavities of the main brake and all wheel cylinders are filled with brake fluid. The regulator shown in the figure braking forces and anti-lock braking system modulator, when installed on a vehicle, are also part of the hydraulic drive.
When the pedal is pressed, the brake master cylinder piston forces fluid into the pipelines and wheel cylinders. In the wheel cylinders, the brake fluid forces all the pistons to move, as a result of which the brake pads are pressed against the drums (or discs). When the gaps between the pads and drums (discs) are selected, the displacement of fluid from the master brake cylinder into the wheel cylinders will become impossible. With a further increase in the force of pressing the pedal in the drive, the fluid pressure increases and the simultaneous braking of all wheels begins.
The greater the force applied to the pedal, the greater the pressure created by the piston of the main brake cylinder on the fluid and the greater the force acting through each piston of the wheel cylinder on the brake shoe. Thus, the simultaneous operation of all brakes and a constant ratio between the force on the brake pedal and the driving forces of the brakes are ensured by the very principle of the hydraulic drive. In modern drives, the fluid pressure during emergency braking can reach 10–15 MPa.
When the brake pedal is released, it moves to its original position under the action of a return spring. The piston of the main brake cylinder also returns to its original position with its spring, the coupling springs of the mechanisms remove the pads from the drums (discs). Brake fluid from the wheel cylinders through pipelines is forced into the main brake cylinder.
Benefits hydraulic drive are the speed of response (due to the incompressibility of the liquid and the high rigidity of the pipelines), high efficiency, since energy losses are mainly associated with the movement of a low-viscosity liquid from one volume to another, simplicity of design, small weight and dimensions due to high drive pressure, ease of layout of devices drive and pipelines; the possibility of obtaining the desired distribution of braking forces between the axles of the car due to the different diameters of the pistons of the wheel cylinders.
The disadvantages of hydraulic drive are: the need for a special brake fluid with a high boiling point and a low thickening point; the possibility of failure in case of depressurization due to leakage of liquid in case of damage, or failure when air enters the drive (formation of vapor locks); a significant reduction in efficiency at low temperatures(below minus 30 °С); the difficulty of using on road trains to directly control the trailer brakes.
For use in hydraulic drives, special fluids are produced called brake fluids. Brake fluids are made on different bases, such as alcohol, glycol or oil. They must not be mixed with each other due to the deterioration of properties and the formation of flakes. In order to avoid the destruction of rubber parts, brake fluids obtained from petroleum products can only be used in hydraulic drives in which seals and hoses are made of oil-resistant rubber.
When using a hydraulic drive, it is always performed as a two-circuit one, and the performance of one circuit does not depend on the state of the second. With such a scheme, with a single fault, not the entire drive fails, but only the faulty circuit. A healthy circuit plays the role of a spare brake system, with which the car stops.

Methods for separating the brake drive into two (1 and 2) independent circuits

The four brake mechanisms and their wheel cylinders can be separated into two independent circuits in various ways, as shown in the figure.
In the diagram (Fig. 5a), the first section of the master cylinder and the wheel cylinders of the front brakes are combined into one circuit. The second circuit is formed by the second section and rear brake cylinders. Such a scheme with axial separation of circuits is used, for example, on UAZ-3160, GAZ-3307 vehicles. The diagonal circuit separation scheme is considered more effective (Fig. b), in which the wheel cylinders of the right front and left are combined into one circuit. rear brakes, and in the second circuit - wheel cylinders of two other brake mechanisms (VAZ-2112). With this scheme, in the event of a malfunction, one front and one rear wheel can always be braked.
In the other schemes shown in Fig. 6.15, after a failure, three or all four brake mechanisms remain operational, which further increases the efficiency of the backup system. So, the hydraulic brake drive of the Moskvich-21412 car (Fig. c) is made using a two-piston caliper of a disk mechanism on the front wheels with large and small pistons. As can be seen from the diagram, if one of the circuits fails, the serviceable circuit of the spare system acts either only on large caliper pistons front brake, or on the rear cylinders and small pistons of the front brake.
In the diagram (fig. d), one of the circuits always remains in good condition, combining the wheel cylinders of two front brakes and one rear ( Volvo car). Finally, in fig. 6.15d shows a scheme with full redundancy (ZIL-41045), in which any of the circuits brakes all wheels. In any scheme, the presence of two independent master brake cylinders is mandatory. Structurally, most often this is a double tandem-type master cylinder, with independent cylinders arranged in series in one housing and driven by a pedal with one rod. But on some cars, two conventional master cylinders are used, installed in parallel with the pedal drive through an equalizing lever and two rods.

The invention relates to the field of electrical engineering, in particular to brake devices designed to stop electrical machines with a low shaft speed. The brake assembly contains an electromagnet, a brake spring, brake discs, one of which is rigidly fixed on the shaft, and the other is movable only in the axial direction. Braking and locking stop is carried out by means of brake discs, the mating surfaces of which are made in the form of radially arranged teeth. The profile of the teeth of one disk corresponds to the profile of the grooves of the other disk. EFFECT: reduced overall dimensions and weight of the brake unit, reduced electric power of the electromagnet, increased reliability and service life of the brake unit. 3 ill.

The invention relates to the field of electrical engineering, in particular to brake devices designed to stop electrical machines with a low shaft speed.

Known self-braking synchronous motor with axial excitation (A.S. USSR No. 788279, N02K 7/106, 01/29/79), containing a stator with a winding, a rotor, a housing and bearing shields made of magnetically conductive material, on the first of which, equipped with an annular a diamagnetic insert, a braking unit in the form of an armature, spring-loaded to a brake unit with a friction gasket, was reinforced, where, in order to increase speed, the electric motor was equipped with a short-circuited electrically conductive ring installed coaxially with the rotor on the second bearing shield.

Known electric motor (patent RU No. 2321142, H02K 19/24, H02K 29/06, H02K 37/10, priority 06/14/2006). A close solution is the second claim of this patent. Electric motor for driving electrical executive mechanisms and devices containing a toothed magnetically soft rotor and a stator made in the form of a magnetic circuit with poles and segments and tangentially magnetized permanent magnets alternating around the circumference, coils of an m-phase winding are placed on the poles, adjacent to each segment permanent magnets of the same polarity, the number of segments and poles is a multiple of 2 m, the teeth on the segments and the rotor are made with equal steps, the axes of the teeth of adjacent segments are shifted by an angle of 360/2 m el. degrees, the windings of each phase are made of a series connection of coils placed on poles spaced from each other by m-1 pole, where, according to the invention, an electromagnetic brake with a friction element is placed on the stator, the movable part of which is connected to the motor shaft, the brake windings are put into operation along with the motor windings.

Known electric motor with an electromagnetic brake manufactured by ESCO LLC, Republic of Belarus, http//www.esco-motors.ru/engines php. The electromagnetic brake fixed on the rear end shield of the electric motor contains a housing, an electromagnetic coil or a set of electromagnetic coils, brake springs, an armature, which is an anti-friction surface for the brake disc, a brake disc with friction non-asbestos linings. At rest, the motor is braked, the pressure of the springs on the armature, which, in turn, exerts pressure on the brake disc, causes the brake disc to lock and creates a braking torque. The release of the brake occurs by applying voltage to the coil of the electromagnet and attracting the armature by the excited electromagnet. The pressure of the armature on the brake disc eliminated in this way causes its release and free rotation with the shaft. electric motor or in conjunction with the brake device. It is possible to equip the brakes with a manual release lever, which ensures that the drive is switched over in the event of a power failure required to release the brakes.

Known brake unit built into the motor, manufactured by CJSC "Belrobot", Republic of Belarus, http://www.belrobot.by/catalog.asp?sect=2&subsect=4. The brake assembly, fixed on the rear end shield of the electric motor, contains a housing, an electromagnet, springs, an armature, an adjusting disc, a brake disc with double-sided friction linings, a brake torque adjustment screw. In the absence of voltage on the electromagnet, the spring moves the armature and presses the brake disc against the setting disc, connecting the motor rotor and its housing through the friction surfaces. When voltage is applied, the electromagnet moves the armature, compressing the springs, and releases the brake disc, and with it the motor shaft.

The common disadvantages of the devices described above are the wear of the brake disc linings, the sufficiently large power consumption of the electromagnet to overcome the clamping force of the spring and, as a result, large dimensions and mass.

The purpose of the claimed invention is to reduce the overall dimensions and weight of the brake assembly, reduce the electric power of the electromagnet, increase the reliability and service life of the brake assembly.

This goal is achieved by the fact that in the brake assembly containing an electromagnet, a brake spring, brake discs, one of which is rigidly fixed to the shaft, and the other is movable only in the axial direction, according to the invention, braking and fixing the stop is carried out by means of brake discs, the mating surfaces of which are made in the form of radially arranged teeth, and the profile of the teeth of one disk corresponds to the profile of the grooves of the other disk.

The essence of the invention is illustrated by drawings.

Fig.1 - General diagram of an electric machine with a brake unit.

Figure 2 is a view of a rigidly fixed disk of the brake assembly.

Fig. 3 is a view of an axially movable disk of the brake unit.

The brake unit contains an electromagnet 1, a brake spring 2, a brake disk rigidly fixed on the shaft ( HDD) 3, coaxially to which the axially movable brake disc (movable disc) 4 is located and guides 5 fixed on the bearing shield, along which the movable disc 4 moves. The mating surfaces of the brake discs are made in the form of radially arranged teeth. The number, geometric dimensions and strength of the teeth of the brake discs 3 and 4, as well as the strength of the guides 5, are calculated so as to withstand the forces arising from the forced stop of the rotating shaft. For guaranteed engagement during rotation of the shaft with a hard disk, grooves can be made hard drive width, much larger than the width of the teeth of the movable disk, and the spring force should provide the necessary speed of entry of the teeth into the grooves. It should be noted that the mating surfaces can be made in the form of splines or similar elements, which is not an essential feature, but the profile of the teeth of one disk must match the profile of the grooves of the other disk for free engagement.

For more convenient consideration in Fig.2 and 3 shows a special case of the location of the teeth on the mating surfaces of the brake discs. In figure 2, the hard disk 3 has 36 teeth 6, and in figure 3 the movable disk has 3 teeth 7. The profile of the teeth 7 of the movable disk 4 corresponds to the profile of the grooves of the hard disk 3.

The brake assembly works as follows

In the absence of voltage on the electromagnet 1, the spring 2 holds the movable disk 4 so that its teeth 7 are in the grooves located between the teeth 6 of the hard disk 3, forming an engagement that securely fixes the shaft.

When voltage is applied to the electromagnet 1, the movable disk 4 moves along the guides 5 to the electromagnet 1 under the influence of electromagnetic forces and, compressing the spring 2, releases the shaft.

When the supply voltage is suddenly turned off, the electromagnetic connection between the electromagnet 1 and the movable disk 4 disappears, the spring 2 moves the movable disk 4 and its teeth 7 enter the grooves of the hard disk 3, forming an engagement that securely fixes the shaft.

It is obvious to those skilled in the art that braking with brake discs having radial teeth on their mating surfaces, compared to braking with brake discs with linings, requires less spring force, which in this case only moves the movable disc, but does not create a braking torque. , while spending significantly less electrical power, thereby reducing the overall dimensions and weight of the brake assembly. Tooth-to-groove engagement of the brake discs ensures reliable stop locking, preventing the shaft from turning, and the exclusion of brake disc linings increases the service life of the brake assembly and the entire electric machine.

Brake assembly containing an electromagnet, a brake spring, brake discs, one of which is rigidly fixed on the shaft, and the other is movable only in the axial direction, characterized in that braking and fixing the stop is carried out by means of brake discs, the mating surfaces of which are made in the form of radially arranged teeth , and the profile of the teeth of one disk corresponds to the profile of the grooves of the other disk.

1. Remove the panel covering the brake pedal assembly.

2. Remove the protective shield.

3. Disconnect the brake pedal position sensor cable connector from the pedal assembly.

4. Take out cotter pin and remove the finger connecting a pusher of the vacuum booster with a brake pedal.

5. Remove and discard the three nuts securing the brake pedal assembly to the body panel.

6. Separate the brake pedal assembly and remove it from the vehicle.

NOTE: Do not further disassemble if the assembly is being removed for ease of access only.

7. Release and remove the brake pedal position sensor from its socket.

8. Remove the sensor socket from the brake pedal bracket.

9. Remove the brake pedal return spring.

10. Turn away two nuts and take out two bolts of fastening of an arm of a returnable spring to knot of a brake pedal. Remove the spring bracket.

Assembly

1. Install the return spring bracket on the brake pedal assembly, insert the mounting bolts, screw the nuts onto them and tighten them with a torque of 10 Nm.

2. Connect the return spring to the pedal bracket and install the pedal position sensor on it.

3. Install the pedal assembly to the body panel, install new nuts and tighten them to 26 Nm.

CAUTION: The nuts connecting the vacuum booster to the pedal bracket must be re-tightened after 30 minutes.

4. Establish the gauge of position of a brake pedal in a socket, connect a block of a wire to its socket and fix it in a socket.

5. Connect the pusher to the pedal, insert your finger and install the cotter pin in its hole.

6. Make sure the sensor makes contact with the protrusion of the pedal when the pedal is in the up position.

7. Replace the protective shield.

CAR INTERIOR PARTS, REPAIR WORKS, Control panel lower cover.

8. Replace the panel covering the brake pedal assembly.

VEHICLE INTERIOR PARTS, REPAIR WORKS, Control panel lower shield - passenger side.

Brake system car (eng. - brake system) refers to systems active safety and is designed to change the speed of the car up to its complete stop, including emergency, as well as to hold the car in place for a long period of time. To implement the listed functions, the following types of brake systems are used: working (or main), spare, parking, auxiliary and anti-lock (system exchange rate stability). The totality of all braking systems of a car is called brake control.

Working (main) brake system

The main purpose of the service brake system is to regulate the speed of the vehicle until it comes to a complete stop.

The main brake system consists of a brake drive and brake mechanisms. On passenger cars, a hydraulic drive is mainly used.

Scheme of the brake system of the car

The hydraulic drive consists of:

• (in the absence of ABS);
• (in the presence of);
• working brake cylinders;
• working circuits.

The brake master cylinder converts the force supplied by the brake pedal driver into pressure. working fluid in the system and distributes it to the working circuits.

To increase the force that creates pressure in the brake system, the hydraulic drive is equipped with.

The pressure regulator is designed to reduce the pressure in the rear wheel brake drive, which contributes to more efficient braking.

Types of circuits of the brake system

The circuits of the brake system, which are a system of closed pipelines, connect the main brake cylinder and the brake mechanisms of the wheels.

Contours can duplicate each other or perform only their functions. The most demanded is a two-circuit brake drive circuit, in which a pair of circuits operates diagonally.

Spare brake system

The spare brake system is used for emergency or emergency braking in case of failure or malfunction of the main one. It performs the same functions as a service brake system and can function both as part of a working system and as an independent unit.

Parking brake system

The main functions and purpose are:

• retention vehicle in place for a long time;
• exclusion of spontaneous movement of the car on a slope;
• emergency and emergency braking in case of failure of the service brake system.

The device of the brake system of the car

Brake system

The basis of the brake system is the brake mechanisms and their drives.

The brake mechanism is used to create the braking torque necessary for braking and stopping the vehicle. The mechanism is mounted on the wheel hub, and the principle of its operation is based on the use of friction force. Brakes can be disc or drum.

Structurally, the brake mechanism consists of static and rotating parts. The static part of the drum mechanism is represented, and the rotating part is brake pads with overlays. In the disc mechanism, the rotating part is represented by a brake disc, the fixed part is represented by a caliper with brake pads.

Controls the brake mechanisms drive.

Hydraulic drive is not the only one used in the braking system. So in the parking brake system, a mechanical drive is used, which is a combination of rods, levers and cables. The device connects the brake mechanisms of the rear wheels with. There is also one that uses an electric drive.

A hydraulically actuated braking system can include a variety of electronic systems: anti-lock braking system, vehicle stability control, emergency brake booster, .

There are other types of brake drive: pneumatic, electric and combined. The latter can be represented as pneumohydraulic or hydropneumatic.

The principle of operation of the brake system

The operation of the brake system is built as follows:

1. When you press the brake pedal, the driver creates a force that is transmitted to the vacuum booster.
2. Further, it increases in the vacuum booster and is transmitted to the main brake cylinder.
3. The GTZ piston pumps the working fluid to the wheel cylinders through pipelines, due to which the pressure in the brake actuator increases, and the pistons of the working cylinders move the brake pads to the discs.
4. Further depressing the pedal further increases the fluid pressure, due to which the brake mechanisms are activated, leading to a slowdown in the rotation of the wheels. The pressure of the working fluid can approach 10-15 MPa. The larger it is, the more effective the braking is.
5. Lowering the brake pedal causes it to return to its original position under the action of a return spring. The GTZ piston also returns to the neutral position. The working fluid also moves to the brake master cylinder. The pads release the discs or drums. The pressure in the system drops.

Important! The working fluid in the system must be changed periodically. How much for one replacement? Not more than a liter and a half.

The main malfunctions of the brake system

The table below lists the most common vehicle brake problems and how to fix them.

Symptoms	Probable Cause	Solutions
Whistling or noise heard when braking	Wear of brake pads, their poor quality or marriage; deformation of the brake disc or the ingress of a foreign object on it	Replacing or cleaning pads and discs
Increased pedal travel	Leakage of working fluid from wheel cylinders; air entering the brake system; wear or damage to rubber hoses and gaskets in the GTZ	Replacement of defective parts; bleeding the brake system
Increased pedal force when braking	Failure of the vacuum booster; hose damage	Replacing the booster or hose
All wheel lock	Piston jamming in the GTZ; no pedal free play	GTZ replacement; setting the correct free play

Conclusion

The braking system is the basis safe movement car. Therefore, close attention should always be paid to it. In the event of a malfunction of the service brake system, the operation of the vehicle is prohibited completely.

The brake system is designed to control the speed of the car, stop it, and hold it in place for a long time by using the braking force between the wheel and the road. Braking force can be generated by a wheel brake, a vehicle engine (called engine braking), a hydraulic or electric retarder in the transmission.

To implement these functions, the following types of brake systems are installed on the car: working, spare and parking.

Service brake system provides controlled deceleration and stopping of the vehicle.

Spare brake system used in case of failure and malfunction of the working system. It performs the same functions as working system. A spare brake system can be implemented as a special autonomous system or as part of a working brake system (one of the brake drive circuits).

Depending on the design of the friction part, drum and disc brake mechanisms are distinguished.

The brake mechanism consists of a rotating and a fixed part. As a rotating part of the drum mechanism is used brake drum, fixed part - brake pads or bands.

The rotating part of the disc mechanism is represented by a brake disc, the fixed part is represented by brake pads. On the front and rear axle contemporary cars usually disc brakes are installed.

Disc brake consists of a rotating brake disc, two fixed pads mounted inside the caliper on both sides.

caliper fixed on the bracket. Working cylinders are installed in the grooves of the caliper, which, when braking, press the brake pads against the disc.

Brake disk when heated, they get very hot. The brake disc is cooled by air flow. For better heat dissipation, holes are made on the surface of the disk. Such a disk is called ventilated. To improve braking performance and provide resistance to overheating on sports cars ceramic brake discs are used.

brake pads are pressed against the caliper by spring elements. Friction linings are attached to the pads. On the modern cars The brake pads are equipped with a wear sensor.

Brake drive Provides brake control. The brake systems of automobiles use the following types of brake actuators: mechanical, hydraulic, pneumatic, electric and combined.

mechanical drive used in the parking brake system. The mechanical drive is a system of rods, levers and cables that connects the parking brake lever to the brake mechanisms of the rear wheels. It includes the drive lever, adjustable end cables, cable equalizer and shoe drive levers.

On some car models, the parking system is actuated by a foot pedal, the so-called. parking brake with foot drive. Recently, an electric drive has been widely used in the parking system, and the device itself is called an electromechanical parking brake.

Hydraulic drive is the main type of drive in the service brake system. The design of the hydraulic drive includes the brake pedal, brake booster, brake master cylinder, wheel cylinders, connecting hoses and pipelines.

The brake pedal transfers force from the driver's foot to the brake master cylinder. The brake booster creates additional force transmitted from the brake pedal. The vacuum brake booster has found the greatest application on cars.

Pneumatic drive used in brake system trucks. Combined brake drive is a combination of several drive types. For example, an electro-pneumatic drive.

The principle of operation of the brake system

The principle of operation of the brake system is considered on the example of a hydraulic working system.

When you press the brake pedal, the load is transferred to the amplifier, which creates additional force on the main brake cylinder. The brake master cylinder piston pumps fluid through pipes to the wheel cylinders. This increases the fluid pressure in the brake actuator. The pistons of the wheel cylinders move the brake pads to the discs (drums).

Further pressure on the pedal increases the fluid pressure and the brakes are activated, which slows the rotation of the wheels and the appearance of braking forces at the point of contact of the tires with the road. The more force is applied to the brake pedal, the faster and more efficiently the wheels are braked. The fluid pressure during braking can reach 10-15 MPa.

At the end of braking (releasing the brake pedal), the pedal under the influence of a return spring moves to its original position. The piston of the main brake cylinder moves to its original position. Spring elements take the pads away from the discs (drums). The brake fluid from the wheel cylinders is forced through pipelines into the master brake cylinder. The pressure in the system drops.

The effectiveness of the braking system is significantly increased through the use of active vehicle safety systems.