The SPbGASU Department of Land Transport and Technological Machines (LTTM) is conducting a research to improve the designs of construction and transport equipment for use in Arctic conditions. One of the areas of research is ensuring the smooth running of transport and technological machines used in construction and made on the basis of truck chassis (excavators, cranes, concrete mixers, etc.). It is precisely this highly mobile equipment that can ensure significant rates of development of the northern territories.
However, the implementation of the mobile qualities of the TTM is hampered by two problems: the standard suspension of the basic automobile chassis does not provide a smooth ride on rough roads typical of the Arctic, as a result of which the driving speed is significantly reduced; low temperatures practically block the shock-absorbing properties of the suspension in the initial period of movement, when the working fluid of the hydraulic shock absorbers used to dampen vibrations in the chassis suspension is not warmed up to a positive temperature. Blocking of shock absorbers occurs due to a significant increase in the kinematic viscosity of the shock-absorber fluid at subzero temperatures, and the fluid stops being pumped through the narrow channels of the throttle-valve system. In this case, the shock absorber fluid solidifies during twenty minutes of parking the car at an air temperature below –30° C. During the period of warming up the shock absorbers, the car moves with virtually no softening of shocks from the road, so the moving speed does not exceed 10 km/h.
Previously, scientists from the Department of LTTM found a solution to the first problem: they proposed using a specially designed hydraulic shock absorber in the chassis suspension with a built-in gas spring, providing a progressive elastic characteristic, and a throttle-valve system, providing a progressive-regressive damping characteristic (Two-pipe hydropneumatic shock absorber - utility model patent No. 194004 30.07.19). Computer modeling has shown that this suspension design significantly reduces the amplitude of vibrations of the TTM chassis when driving on a road with large irregularities, which significantly increases the speed of the vehicle.
The solution to the second problem was obtained as a result of research within the framework of a grant competition for the implementation of scientific research works by SPbGASU scientific and pedagogical workers in 2024. It was proposed to include in the design of the shock absorber described above an additional device that, at the solidification temperature of the shock absorber fluid, opens a channel with low hydraulic resistance for passage fluid bypassing the main throttle valve system (Fig. 1).
At a positive temperature, valve 3 of thermostat 4 locks the lower hole of the sleeve 1 of the throttle valve system (TVS). The shock absorber operates in normal mode, providing the required damping capacity by flowing shock absorber fluid through the booster compressor. As the temperature decreases, the volume of refrigerant in the thermostat decreases, and valve 3 opens the lower hole of the TVS sleeve. The stronger the cooling, the higher the throughput. When the temperature of the shock absorber fluid is below –25° C, the frozen fluid stops being pumped through the booster compressor and passes only through an additional channel.
Computer modeling has shown that the new shock absorber provides the required parameters of elastic and damping characteristics when the main booster compressor is blocked at temperatures below minus –25° C.
An application for a utility model has been submitted for the design of the new shock absorber, and an application for a certificate for a computer program has been submitted for the computer model.
