THE PRINCIPLE OF CONSTRUCTING A MICROSYSTEM INDICATOR OF THE STATE OF THE BRAKE PAD OF A ROBOTIC CAR

Проблема и цель. С развитием и широким применением колесной наземной транспортной техники выдвигаются повышенные требования к устройству машин, их управляемости с одновременным упрощением требований к водителю по управлению машиной и обеспечению ее функционирования в широком диапазоне технических возможностей. Целью исследований явилось теоретическое обоснование и практическая реализация способа непрерывного мониторинга состояния накладок тормозных колодок автомобиля КамАЗ. Методология. Разработано микросистемное устройство для контроля состояния тормозной колодки, отвечающее требованиям автоматизации и роботизации. Электрическая схема устройства построена по аналоговой форме с непрерывной регистрацией неэлектрического сигнала о состоянии (толщине износа) накладки в преобразованной электрической форме. Принцип действия сигнализатора состояния тормозной колодки автомобиля построен на использовании явления изменения электрической емкости конденсатора с изолирующей прокладкой между электродами при изменении толщины этого изолятора. Если встроить в керамическую (изолирующую) накладку тормозной колодки металлический электрод, то он образует электрическую емкость с поверхностью тормозимого металлического тела. Это позволяет в качестве изолирующей прокладки использовать изнашивающийся слой фрикционной накладки тормозной колодки. В таком датчике первичным источником информации будет являться непосредственно контролируемый параметр – остаточный рабочий слой фрикционной накладки тормозной колодки Результаты. Разработано индикаторное устройство, позволяющее водителю, находящемуся в кабине автомобиля, не отрываясь от управления осуществлять непрерывный мониторинг состояния тормозных накладок (толщины рабочего слоя) вплоть до критического, при котором дальнейшая эксплуатация транспортного средства становится небезопасной. Заключение. Применение разработанного индикаторного устройства для визуального функционального контроля водителем состояния тормозных колодок автомобиля делает возможным предотвращение нештатных ситуаций, которые могут возникнуть из-за невозможности эффективного использования рабочей тормозной системы автомобиля по причине предельно допустимого или неравномерного износа фрикционных накладок тормозных колодок. Problem and purpose. With the development and widespread use of wheeled ground transport equipment, increased requirements are put forward for the device of machines, their controllability, while simplifying the requirements for the driver to control the machine and ensure its functioning in a wide range of technical capabilities. The aim of the research was the theoretical substantiation and practical implementation of the method for continuous monitoring of the state of the brake pads of the KamAZ car. Methodology. Microsystem device for monitoring the condition of the brake pad, which meets the requirements of automation and robotization. The electrical circuit of the device is built in an analog form with continuous registration of a non-electrical signal about the state (wear thickness) of the pad in a converted electrical form. The principle of operation of the signaling device of the state of the brake shoe of a car is based on the use of the phenomenon of change in the electrical capacitance of a capacitor C with an insulating gasket between the electrodes when the thickness of this insulator changes. If a metal electrode is embedded in the ceramic (insulating) lining of the brake shoe, then it forms an electric capacitance C with the surface of the braking metal body. This allows the wear layer of the brake pad friction lining to be used as an insulating pad. In such a sensor, the primary source of information will be the directly monitored parameter - the residual working layer of the friction lining of the brake shoe Results. Development of an indicator device that allows the driver, who is in the cab of the car, without interrupting control, to continuously monitor the state of the brake linings (thickness of the working layer) up to the critical state, at which the further operation of the vehicle becomes unsafe. Conclusion. The development of an indicator device for visual functional control by the driver of the state of the brake pads of a car makes it possible to prevent abnormal situations that may arise due to the impossibility of effective use of the working brake system of the car, due to the maximum permissible or uneven wear of the friction linings of brake pads.

Wear analysis of eco-friendly non-asbestos friction-lining material applied in an automotive drum brake: Experimental and finite-element analysis

Brake friction lining material is the critical element of a braking system, since it provides friction resistance to the rotating drum for controlling automobiles. The present study involves wear analysis of newly developed eco-friendly non-asbestos friction lining material for automotive drum brake applications using experimental study, finite-element analysis, and microstructural investigations. Theoretical interpretation of braking force at different automobile speeds was derived using fundamentals. Specimen drum brake liner with eco-friendly material compositions was produced using an industrial hot compression molding process at one of the manufacturer. The surface wear of the liner was measured using an effective and accurate method. Furthermore, a finite-element analysis model was developed considering actual operating conditions and various components of the drum brake system. The model was elaborated for various result outcomes, including Von-Mises stresses and total deformation of components of the drum brake, and further used to estimate the surface wear of the friction lining material in terms of transverse directional deformation. Finally, microstructural analysis of the friction lining material was carried out using scanning electron microscopy and energy dispersive spectroscopy. From the results, it is seen that the developed friction lining material is wear resistant. The finite-element analysis model can be effectively utilized to study the tribological characteristics of friction lining materials.

Response Characteristics of Dynamic Torque for Wet Clutch Engagement: A Numerical and Experimental Study

To determine the factors affecting the dynamic transmitted torque response characteristics of the wet clutch, the oil film pressure, the asperity contact pressure, the applied pressure, and the dynamic transmitted torque model were established, using the fourth-order Runge–Kutta numerical method to couple the oil film thickness and the speed difference to obtain the change curve of the joint pressure and the transmitted torque. The established model was used to study the influence of the pressure hysteresis time, lubricant viscosity, friction lining permeability, friction pair equivalent elastic modulus, and surface combined roughness RMS on the dynamic transmitted torque response during the wet clutch engagement. The results indicate that the longer the pressure hysteresis time, the smaller the permeability of the friction lining, the smaller the equivalent elastic modulus, the greater surface combined roughness RMS, the more delayed the response of the transmitted torque, and the smaller the level of jerk of the wet clutch engagement. Also, the lower the lubricant viscosity, the greater the permeability of the friction lining, and the smaller the equivalent elastic modulus is and the greater surface combined roughness RMS is, the more sensitive the transmitted torque response is to pressure response changes.

Friction lining coefficient of the drive friction pulley

Mine hoisting KOEPPE system or friction hoist winch work with traction pulley, the pulley rim grooves are lined. Lining has to provide a higher friction coefficient between the rope and the traction pulley. The constructors of mine hoisting machines require from the manufacturers a guaranteed appropriate and stabile value of a friction coefficient at different pressures between a rope and a friction lining under different external conditions (drought, moisture, icing, etc.). The paper presents processed measurements performed on the six samples of the friction lining (G1-G6) made of rubber and the sample of the standard used friction lining (K25). The samples (G1-G6) differ in the chemical composition of the rubber. Due to the confidentiality of the material composition of the friction linings the hardness of the lining material as a discriminator was chosen. The measured values of the friction coefficient of the rubber friction lining samples were compared with the values of the friction coefficient of the friction lining (K25) usually mounted on friction lining pulley.

Distribution of Static Deformations along the Friction Lining of the Brake Mechanism in the Cars of GAZelle Series

The study of the shoe lining in the drum brake mechanism is of paramount importance to evaluate its wear regularity. Thereto, the computational scheme of the drum brake-shoe mechanism has been designed, the calculation formulae of tangential and radial components of the external points displacement in the lining have been analyzed, by means of which their numerical values have been determined, the diagram of the radial displacements has been designed and compared with descriptors of the wear change along the friction lining, according to which they alter with similar regularities.

The influence of the length of the lining on the speed of movement of the pallet on the centrifugal friction roller

Pallet flow rack is one of the high-density storage systems. One of the main safety elements of the systems is a brake roller. Centrifugal frictional brake is the widely used type of the brake rollers, which used as speed governor for the pallet. The known method of calculation of the pallet speed on the flow rack does not take into account the length of the friction lining. In reality, the contact of the friction lining and the roller shell occurs in an arc that reaches the full length of the lining during operation. The method of calculating the speed of movement of the pallet on a centrifugal friction roller is given, and a calculation formula is obtained that allows taking into account the uniform distribution of the force of the normal pressure along the length of the lining. The results of a comparative calculation are presented, which showed that the speed of the pallet movement when taking into account the length of the lining is lower than the values obtained without taking it into account. It is found that if the lining length is up to 70 mm, it can be ignored in the calculations using a simpler formula, and if the lining length is more than 70 mm, it is recommended to use the calculation formula obtained in the work.