Применение вибродиагностики при создании элементов персонального электротранспорта

The study of vibration loading of the main elements of personal electric vehicles and the search for ways to reduce vibration characteristics was conducted. The issues of measuring vibration arising on a bicycle, which is driven by human muscle power and an electric drive, are considered. Measurements of vibration acceleration and frequency spectra in a certain area of motion were carried out using the “Octave-101VM” spectrum analyzer in three stages. At the first stage, the electric bike was driven by a pedal drive, at the second – by an electric drive, at the third – the pedals and the electric drive worked in parallel. As a result of the tests carried out, it was found that the greatest vibration occurred in the “Motor” mode during the use of an electric bicycle, the least vibration occurred when driving with the electric motor turned off. It was found that the electric drive increases the vibration level (at the same time, the electric bike does not exceed the maximum permissible values of vibration levels on all axes). In order to reduce the vibration arising from the electric motor on a personal electric vehicle, a 3D computer model has been developed and an airless wheel mover has been manufactured using this model on a 3D printer (a wheel for an electric scooter with internal damping has been manufactured). Bench tests have shown that the developed wheel, in comparison with a pneumatic tire, has a smaller (up to 45 %) contact spot. The results obtained can be used in the development of competitive products, in particular personal electric vehicles.Проведено исследование вибронагруженности основных элементов персональных электрических транспортных средств и поиск путей снижения вибрационных характеристик. Рассмотрены вопросы измерения вибрации, возникающей на велосипеде, который приводится в движение мускульной силой человека и электроприводом. Измерения виброускорения и частотных спектров на определенном участке движения осуществлялись с помощью анализатора спектра «Октава-101ВМ» в три этапа. На первом этапе электровелосипед приводился в движение с помощью педального привода, на втором – электроприводом, на третьем – педали и электропривод работали параллельно. В результате проведенных испытаний установлено, что наибольшая вибрация происходила в режиме «Мотор» в процессе использования электровелосипеда, наименьшая вибрация – при езде с выключенным электродвигателем. Обнаружено, что электропривод увеличивает уровень вибрации (при этом у электровелосипеда по всем осям не происходит превышения предельно допустимых значений уровней вибраций). С целью уменьшения возникающей от электродвигателя вибрации на персональном электротранспорте разработана компьютерная 3D-модель и изготовлен по данной модели на 3D-принтере безвоздушный колесный движитель (колесо для электросамоката с внутренним демпфированием). Стендовые испытания показали, что разработанное колесо в сравнении с пневматической шиной имеет меньшее (до 45 %) пятно контакта. Полученные результаты можно использовать при разработке конкурентоспособной продукции, в частности персонального электротранспорта

Токопроводящие материалы для соединительных шин многоэлементных аккумуляторных тяговых батарей

The article deals with the choice of materials for connecting tires of traction batteries (TB). The optimal parameters of their spot welding with batteries are experimentally established (the first pulse with a current of 7 kA duration of 1 ms, the break between the pulses of 1 ms, the second pulse with a current of 7 kA duration of 2 ms). When operating the traction battery on electric vehicles, the resistance of the connecting tires should not lead to heating of the batteries in order to avoid overheating above 60 °C. In most modern TB, consisting of Li-ion elements, a nickel tape is used for the connection. To ensure the weldability of materials (copper–nickel or nickel–nickel), it is important that the operating temperature is reached at a short-term current pulse in the welding zone. One of the solutions to this problem is the application of a metal coating. Experiments were conducted on the weldability of various materials, including those with applied coatings. The best results in weldability were shown by tires made of tinned copper, which was welded to nickel plates (emitting the battery body). Tear tests of the welded samples were carried out. The tensile strength of the original copper tires was 340–450 MPa. When welding copper–nickel and copper(tinned) – nickel plates, the strength limit values reach 70 % of the strength of the original copper plate. On the basis of the obtained experimental data, a pilot batch of battery TB was manufactured, which successfully passed tests for compliance with the technical requirements for the strength and the value of the transition resistances of the welded joints of connecting buses with batteries.Рассмотрены вопросы выбора материалов для соединительных шин тяговых батарей (ТБ). Экспериментально установлены оптимальные параметры их точечной сварки с элементами питания: первый импульс с силой тока 7 кА длительностью 1 мс, перерыв между импульсами 1 мс, второй импульс с силой тока 7 кА длительностью 2 мс. При работе ТБ на электротранспорте сопротивление соединительных шин не должно приводить к нагреву элементов питания во избежание перегрева выше 60 °С. В большинстве современных ТБ, состоящих из литий-ионных элементов, для соединения используется никелевая лента. Для обеспечения свариваемости материалов (медь–никель или никель–никель) важно, чтобы при краткосрочном импульсе тока в зоне сварки была достигнута рабочая температура. Один из вариантов решения данной задачи – это нанесение металлического покрытия. Проведены эксперименты по свариваемости различных материалов, в том числе с нанесенными покрытиями. Наилучшие результаты по свариваемости показала шина из луженой меди, которую приваривали к никелевым пластинам, эмитирующим корпус элемента питания. Проведены испытания на разрыв сваренных образцов. Предел прочности на разрыв исходных шин меди составил 340–450 МПа. При сваривании пластин медь–никель и медь (луженая) – никель показатели предела прочности достигли 70 % от прочности исходной медной пластины. На основании полученных экспериментальных данных изготовлена опытная партия аккумуляторных ТБ, которая успешно прошла испытания на соответствие техническим требованиям по прочности и величине переходных сопротивлений сварных соединений соединительных шин с элементами питания

Changing of milk freezing temperature after introduction of new requirements to its acidity

The article deals with some consequences of changing requirements to the level of cow milk acidity under different thermal treatment. The factors, which affect the normalized acidity values of raw milk, are under consideration. The interconnection of cryoscopic temperature and titratable acidity of the product is shown. The general dynamics of freezing temperature changes of heat-treated milk has been traced by the example of three finishedproducts from well-known Belarusian producers for a few last years. It is shown the decrease of freezing point for milk products after introduction of more stringent requirements to acidity of the raw material

Analysis of milk some physical-chemical properties after introduction of new requirements to its acidity

Some consequences of recent change of the demands to cow fluid milk acidity are discussed. The average results of freezing point, titratable and active acidities, conductivity, water activity, density, moisture, nonfat milk solids of milk were analyzed. The samples of market pasteurized milk, ultra-high-pasteurized milk, sterilized milk and baked milk were investigated. The factors that affect the normalized titratable and active acidities value were described. The relationship between the study of physical and chemical properties is shown. The dynamics of their changes in drinking milk in recent years is traced. Losses of the freezing point, pH and titratable acid ity of dairy products following the introduction of new requirements to its acidity were demonstrated. The amount of ions and nonfat milk solids in pasteurized milk were increased. The water activity and nonfat milk solids in ultra-high-pasteurized milk were not changed. The stabilization of moisture in sterilized milk and increase the conductivity of baked milk is shown. The technological modes produces of drinking milk led to increase the pH value range

Sorption isotherms of milk mixture

The article contains a brief description of water activity determination. The impact of water activity on the humidity of the food and it affecting microbial cells are described. Definition and classification of sorption isotherms with a brief description of each type are considered. Sorption isotherms of food materials are generally in sigmoid shape. There are given for each type of sorption isotherms the examples of products that lead the type. Sorption isotherms for products with high humidity are shown. The technology of sample preparation and the experiment conduction are described in detail. It is analyzer Roremeter RM-10 was used in the work. The analyses of inert fillers like cellit powder, which are used when liquid samples, is given. The freezing point of the milk product was measured for liquid (not thick) solutions. Humidity measurement of native samples were carried out by express method with hygrometer Radwag. The initial values of water activity, the freezing temperature, and humidity of the native samples of powdered milk and sterilized milk are given. The sorption isotherms of dairy product of various fat content, when it is produced with sterilized milk or distilled water, are shown. The conclusions about contribution in type of sorption isotherm of sample and it components internals are given