SU988613A2 - Electropneumatic modulator for counterblocking brake system of motor vehicle - Google Patents

Description

(54) ELECTROPNEUMATIC MODULATOR FOR ANTI-LOCK BRAKE SYSTEM

CAR

one

The invention relates to mechanical engineering and can be used in transportation technology in pneumatic brake systems of automobiles.

According to the main author. St. No. 749712 is a known electropneumatic modulator for an anti-lock braking system, comprising a pressure control valve, a follower element with a stem, installed with the ability to interact with the indicated valve, and two electrovalves, one of which is installed in the supply system and the other in the compressed air exhaust system into the atmosphere from the control cavity formed by the tracking element on the side opposite to the pressure control valve.

In this modulator, there is an adjustable choke installed in the system for exhausting air from the control cavity behind the solenoid valve, and the throttle is controlled according to the position of the follower element 1.

However, the intensity and magnitude of the pressure drop in the initial period and the difficulty of controlling the intensity of the discharge in the subsequent period increase the depth of the control cycle, increase the frequency of regulation, increase air flow and dynamic loads during braking.

The purpose of the invention is to increase the efficiency of the modulator.

This goal is achieved by the fact that in the modulator an adjustable choke is installed in the hole of the tracking element, which communicates the control cavity with the atmosphere.

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FIG. 1 shows a modulator; a slit; in fig. 2 — choke located in the next element; in fig. 3 — oscillograms of the known workflow and

15 of the proposed modulators.

In the modulator housing 1, a pressure control valve 2 is installed, pressed by spring 3 to seat 4. Follower element 5, which interacts with valve 2, has a central brush 6 mounted in the cylindrical cavity 7, which is permanently in communication with the atmosphere through throttles 8 in the next element 5. In the system for supplying compressed air from the brake valve (not shown) through the input 9, the cavity 10

In the control cavity 11, there is a normally open electro-valve 12.

The control cavity 11 is formed by the follower element 5 on the side opposite to the valve 2. To improve the characteristics of the modulator, the volume of the control cavity 11 - Vi should be as small as possible. Valve 13 is built into the modulator.

In the system for exhausting air from the control cavity 11 into the atmosphere, a throttle 8 is installed, made in the following element 5. The total volume of the cavities 14-Va and 7-UZ is determined by the required value of the pressure reduction to overcome the hysteresis of the brake mechanism and the dynamic resistance of the line from the solenoid valve to the throttles, it provides an intensive decrease in pressure in the control cavity.

Input 15 is designed to supply compressed air from a power supply receiver (not shown) to the valve 2 of the modulator, and through terminal 16 the modulator is connected to the brake chambers of the car (not shown).

The modulator operates as follows.

When the brake pedal is pressed, the compressed air enters through the inlet 9 into the cavity 10 of the solenoid valve 12, and then into the control cavity 11. The following element MeHt 5 under the action of air pressure moves and, overcoming the force of the spring 3, depresses valve 2 from the saddle 4. When This compressed air enters from the receiver through the inlet 15, the check valve 2 and the outlet 16 to the torch chambers of the car.

If during braking there is a danger of locking the wheels of the car, the control unit of the anti-lock braking system (not shown) generates signals to activate the solenoid valves 12 and 13. The solenoid 12 cuts off the control cavity 11 from the air supply system, and the solenoid 13 connects the control cavity 11 through the cavity 7, the throttle 8 and the valve cavity 2 with the atmosphere. At the initial time of opening of the valve 13, the pressure in the control cavity 11 drops sharply, and the pressure drop is determined by the ratio of the volume of the cavities 11, 7 and 14, and the intensity of the fall is determined by the dynamic resistance of the connecting line control cavity 11 - the throttle 9. Drop size and the intensity is determined from the condition of overcoming the hysteresis of the brake mechanism and is approximately 20-40 ° / o from the initial pressure and can be adjusted depending on the dynamic characteristics of a tiblokirovochnoy brake system. The follower element 5 moves upward under the action of the pressure difference.

The valve 2 under the action of the spring 3 also moves upwards, thus closing the passage of compressed air from the receiver

It connects to the brake chambers and connects the latter with the atmosphere, ensuring the discharge of air from the brake chambers with the maximum intensity determined by the dynamic resistance of the pneumatic main connecting the output 16 of the modulator with the brake chambers. The release of air from the brake chambers with maximum intensity is maintained until the pressure in the control cavity 11 and the brake chambers is equalized. After pressure equalization, the following

element 5 is in a position in which the intensity of pressure change in the brake chambers and the control cavity 11 is the same and is determined by the intensity of the outflow of air through the throttle 8.

A decrease in air pressure in the brake chambers occurs before the closing of the solenoid valve 13. A repeated increase in pressure in the brake chambers occurs after the opening of the solenoid valve 12.

When repeated danger of blocking

the wheels of the vehicle control cycle repeats.

Varying the magnitude of the initial pressure drop in the control cavity 11, the subsequent intensity of pressure release with the help of throttles, depending on

The dynamic characteristics of the anti-lock system can significantly improve braking performance, as well as the stability and control of the vehicle during braking.

In the graph shown in FIG. 2, curve 17 describes the process of changing the pressure of the proposed modulator, and curve 18 describes the known process.

Intensive pressure release in the initial period of disinhibition allows one to overcome the brake hysteresis much faster and unlock the wheel. Reducing the time of the locked state of the wheel improves the stability and controllability of the car.

Significant decrease in intensity

reducing the pressure in the subsequent period of time allows you to avoid excessive release of the wheel, i.e., increase braking efficiency, reduce dynamic loads, reduce consumption

of air.

Claims (1)

Invention Formula Electropneumatic modulator for antilock braking system of a vehicle according to aut. St. No. 749712 characterized in that, in order to increase the efficiency of the modulator, an adjustable choke is installed in the opening of the tracking element, which communicates the control cavity with the atmosphere. Information sources, taken into account during the examination 1. USSR Copyright Certificate No. 749712, cl. B 60 T 8/02, 1977.