RU2057662C1 - Method of diagnosing vehicle pneumohydraulic brake drive - Google Patents

Abstract

FIELD: transport; maintenance of vehicles. SUBSTANCE: offered method comes to measuring two parameters: time during which air pressure rises to 95% of its asymptotic value and value of piston travel in pneumohydraulic booster. To cut down time, increase accuracy and facilitate diagnosing process, parameters are measured in two check points with preset rate of cutting in of brake valve, without unsealing of drive hydraulic portion. For realizing the method, special diagnosing device has been developed which includes braking automatic device and electronic instrument with pressure and travel transmitters. EFFECT: reduced time taken for diagnosing, increased accuracy and facilitated process of diagnosing. 2 dwg

Description

 The invention relates to techniques for diagnosing vehicle braking systems. The relevance of the development of this method is due to increasing requirements for the state of brake systems of vehicles.

 The closest technical solution to the invention is a method for diagnosing a pneumatic brake drive of a vehicle, which consists in measuring pressure values and response time at characteristic points of the brake drive.

 However, the method does not allow to accurately assess the state of the pneumatic-hydraulic brake drive (GWP) of the vehicle. In addition, the application of this method introduces large errors, since it does not take into account the time the actuator controls the brake drive.

 A known method for diagnosing a brake hydraulic drive of a vehicle, based on the introduction into the hydraulic drive filled with a working fluid of an additional amount of working fluid under controlled pressure. Using this method, the presence of air in the hydraulic drive, leakage of the working fluid from the hydraulic drive, and the strength of the hydraulic drive are determined.

 However, the method requires depressurization of the hydraulic drive, does not allow to evaluate the response time of the drive.

 The purpose of the invention is to increase accuracy, reduce time and simplify the process of diagnosing vehicle GWP.

 This goal is achieved by the fact that the diagnostic parameters are the time of increase in air pressure and the amount of movement of the pistons in the pneumatic actuator (CCP) of the drive, the time of increase of air pressure up to 95% of its asymptotic value in the CCP corresponds to the response time of the drive and characterizes the state of the entire CGP. The magnitude of the displacement of the CCGT pistons for a given time additionally makes it possible to assess the state of the hydraulic part of the drive.

 This goal is achieved by the use of a braking machine, which enables the actuation of the drive control in a time equal to 0.2 s; due to the development of a diagnostic device that allows you to measure the set parameters using two control points in the drive circuit; lack of need for depressurization of the hydraulic part of the drive.

 The method was tested in laboratory conditions at an experimental installation and in operating conditions on a Ural-4320 automobile using a diagnostic device. It was revealed that the proposed method allows us to determine not only the general technical condition of the drive: “Faulty” or “Faulty”, but also to recognize the malfunctions or malfunctioning elements of the drive.

 The diagnosis process is as follows.

 The car’s pneumatic system is filled with air to a certain pressure. The drive control is activated with a set switching speed. Diagnostic parameters are measured. Deviation of the measurement results from the standard values indicates a faulty state of the drive.

 When recognizing faults, the nature of the change in the measurement results is taken into account.

 PRI me R. If there is air in the hydraulic part of the drive, the parameter values increase by 1.5-2 times. Jamming of the piston in the working brake cylinder, clogging of the compensation hole in the hydraulic cylinder of the CCGT unit is accompanied by a slight decrease in the rise time of the air pressure, but the magnitude of the movement of the pistons in the CCGT unit decreases by 5-6% and 15-20%, respectively, when the pipeline cross-section (collapse) is narrowed in the pneumatic part of the drive, the time of increase in air pressure in the CCGT unit is doubled, but the value of the other parameter is practically the same as the norm.

 The leaky state of the hydraulic actuator is determined by the maximum displacement of the pistons in the CCGT unit when the actuator is kept under operating pressure for 5 ± 0.5 min.

 In FIG. 1 shows a device for diagnosing a drive by the proposed method, general view; in FIG. 2 block diagram of an electronic device.

 The device consists of a brake machine 1, an air pressure sensor 8, a piston displacement sensor 10, connected to an electronic device 7 for processing and indicating signals of these sensors. The braking machine 1 is designed to actuate the drive control element for a set time and consists of a pneumatic cylinder with a piston and an output rod with a support pad 2 for acting on the brake pedal, an electromagnetic valve 3, cable 4, by which valve 3 is connected to the device 7 and a flexible pipe 5 with a control valve 6, providing air supply from the vehicle's pneumatic system in the established mode. Since the upper part of the braking machine is pivotally mounted on a special bracket, which is mounted motionlessly in the car cabin, under the influence of appropriate air pressure, the outgoing rod can evenly move the brake pedal to the stop in the limiter and fully engage the brake valve. The inclusion rate is set by valve 6, which regulates the intensity of filling the pneumatic cylinder with air.

 Small-sized sensors 8 and 10 of potentiometric type are designed to receive an analog signal when the air pressure changes and the pistons move to the CCGT unit. They are installed at the corresponding control points of the CCGT unit and cables 9 and 11 are connected to the device 7.

 The operation of the diagnostic device is as follows.

 The “Start” button is turned on, located on the control panel of the device 7. This opens the solenoid valve 3. Air from the vehicle’s pneumatic system enters the braking machine 1, which enables the brake valve to turn on. Analog signals from sensors 8 and 10 are received, processed and displayed by an electronic device. The diagnostic process ends with brake release of the actuator, for which the electromagnetic valve 3 switches to exhaust air from the brake machine, its rod returns to its original position. The drive is being released.

 The electronic device 7 is designed to control the processes of diagnosis, processing signals received from the primary converters, and the presentation of the measurement results in the form of a digital display. The device 7 allows you to measure the time of rise in air pressure from 0 to the set threshold value and the displacement of the CCGT pistons, as well as determine the relative deviation of the measured displacement from its standard value. The device is powered by a 12.0 V battery.

The device includes two measurement schemes:
1. The time measurement scheme, which includes a comparison unit 4, made using a comparator and a trigger, a key 10, which is a 2I-NOT element, a clock pulse generator (GTI) 5, a block 8 of pulse dividers, a counting block of measurement 11, a block of decoders 13, time indication unit 14.

 2. The scheme for measuring the movement and conversion of codes, consisting of an analog-to-digital converter (ADC) 6, a block of registers 9, a block 12 of the conversion of codes and a block 15 of the display. The device 7 provides the inclusion of a brake machine and the operation of the device itself.

 The device operates as follows.

 The increasing analog signal from the sensor 2 enters the block 4 comparison. At the same time, the pulses generated by the GTI with a frequency of 1000 kHz arrive through a divider with a division ratio of 10,000 per key 10. Until the level of the analog signal reaches the threshold value, key 10 is “Open” and the pulses with a frequency of 0.1 kHz arrive at the counting unit 11 of the measurement. When the value of the analog signal reaches the set value, a single signal is set at the output from the comparator of the comparison unit 4, which switches the trigger to the zero state and thereby locks the key 10. The pulse count in block 11 is stopped. The binary code of the read pulses is decrypted into a decimal code by the decoder unit 13 and supplied to the display unit 14, which displays the measurement result.

 In parallel with the described process, when the binary code recorded by the ADC, which is the digital equivalent of the input analog signal of the sensor, is received from the comparison unit 4 to the clock inputs of the registers of a single signal, it is written into the register block 9. The outputs of the registers are connected to the address bus of the code converter executed on integrated circuits and represented (Fig. 2) in the form of a block 12 code conversion. The recorded codes of the values of the measured parameter or relative indicators, depending on the control action for the choice of address space in block 12, are received in block 15 of the display.

Claims (1)

 METHOD FOR DIAGNOSTIC OF AN AIR-HYDRAULIC BRAKE DRIVE OF A VEHICLE, which consists in measuring pressure values and response time at characteristic points and determining the technical condition of the drive by comparing the deviation of the measured parameters from their standard values, characterized in that they additionally measure the time of rise of air pressure in front of the piston and the amount of movement of its pistons for a given time to recognize the likely damage in lementah drive by comparing them with the reference samples, obtained by modeling the characteristic damage and failure.

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