Currently, methods of direct measurement of design parameters of technical condition are used to determine the remaining life of the engine. This requires complete or partial disassembly of the engine, which implies its decommissioning and subsequent placement on repair sites. The main argument in favor of such methods is the reliability of the results obtained, although this increases the labor intensity and cost of this process. The article proposes a method for non-selective evaluation of the residual life of the engine by the transient functions of its systems. The estimated parameters are the transient functions for fuel consumption, air consumption, and crankshaft speed. Quantitative indicators for transient functions are the intensity of changes in the selected parameters when the load is applied. Depending on the technical condition of the internal combustion engine, they have a high, medium and low level. To make a final decision about the technical condition of the engine, the Bayes algorithm on conditional probabilities is used. In case of an unfavorable combination of factors, this algorithm allows to assess the need for work to restore the engine resource with a certain probability. To improve the adequacy of the results obtained, it is necessary to use statistical data that reflect the relationship between the design parameters of the technical condition and the engine running time. The dependence of the selected diagnostic parameters on the technical condition of the engine is reflected in regression equations. Increasing the sample size of available data increases the accuracy of the diagnosis.

One of the important standards of technical operation of motor vehicles is the frequency of their maintenance. The correct definition of it directly affects the amount of specific operating costs and is one of the most important tasks of engineering and technical workers. At the same time, their reduced values, although they lead to an increase in the reliability of vehicles, but they increase the frequency of downtime and the cost of operation, as well as increase the share of unused resources of serviced systems and mechanisms. In this paper, we consider an economic-probabilistic method for determining the frequency of maintenance. There are two tactics for implementing this method: by operating time and by technical condition. For all its simplicity, the method of determining the operating time has a number of disadvantages, namely, it does not take into account the technical condition of the serviced mechanisms and units at the current moment. This increases the complexity of performing maintenance operations, and their cost increases accordingly. The method of determining the frequency of maintenance by condition is considered. In this case, all work on the maintenance of mechanisms and aggregates of vehicles is divided into diagnostic and executive components. At the first stage, their technical condition and resource are determined until the next scheduled maintenance. If this resource is not enough to run before this event, then a decision is made to perform the executive part of the work. With a larger resource, the executive part is postponed until the next scheduled maintenance. The determination of the frequency of maintenance is based on the results of comparing the specific operating costs for routine repairs with the weighted average costs for maintenance and routine repairs.

The purpose of this study is to develop a circuit for an automobile air conditioner, which will reduce the consumption of power developed by the engine. This paper proposes the design of an automobile absorption air conditioner. A description of the principle of operation of an automobile absorption air conditioner operating on a cycle of a one-stage absorption refrigeration machine has been given in the paper. It consists of a stripper (generator), a condenser, an absorber, an evaporator. Lithium bromide (LiBr) solution has been used as an absorbent, which has a low boiling point, is non-toxic and safe. 3D-models of the absorber and generator of an automobile absorption air conditioner has been developed in the course of the research. The absorber is designed to form a weak absorbent solution. This solution is supplied to the generator heat exchanger using a liquid pump. There it is heated by the exhaust gases to the boiling point. The solution evaporates and water vapor enters the condenser (evaporator). In the generator, the solution is concentrated from 52 to 60 %. After that, water vapor is supplied to the absorber from the condenser, and a concentrated absorbent solution is supplied from the generator. It should be noted that the generator is a key element of an automobile absorption air conditioning system. Inside it is a strong LiBr solution that feeds the absorber. The design of the air conditioning system does not provide for the use of a compressor and allows to reduce the power loss of the power plant to the drive of the liquid pump. According to calculations, the pump drive power was 0.17 kW. For comparison, the compressor of a modern car air conditioner consumes 7–11 kW. An absorption car air conditioner provides the following advantages: additional engine cooling, environmental friendliness, fuel economy, efficient use of the heat of vehicle exhaust gases. A distinctive feature of this design is that it is proposed to use the heat of the exhaust gases for the process of heating the absorbent. This design can fully compete with the existing modern car air conditioners.