Abstract
Various designs of CVTs were explored from two points of view: analysis of the design itself and analysis of the methods and techniques, used in the process of creation of the CVT. To solve the problem of finding new designs of mechanisms, the graph transformation method was developed. It includes the following heuristic techniques: a decrease in the number of graph nodes at simplification of a design or to remove non-essential elements; a change in location of graph edges and comparison of a new location of edges and necessary changes in a design; a search for all possible options for location of the parts that correspond to the same graph; introduction to the graph of the nodes, corresponding to the property, for implementation of which a part (a node) can be added to a design or, vice versa, can be removed from a design, and the property it implemented will be implemented by other parts. The original design of the CVT, in which load is transmitted by gear engagement without using friction disks and flexible sections, was developed. A continuously variable of transition ratio is ensured by a gear wheel with a variable pitch. The gear wheel consists of three gear sectors, two of which are involved in meshing. The third unloaded sector performs a turn with angular velocity that is higher than velocity of rotation of the output shaft until it takes a position before coming into engagement. The CVT does not have such drawback as fluctuations of transmission ratio. Based on the analysis of the bond-graphs, efficiency was determined, which depending on velocity of the output shaft is in the range of 95…97 %. The disadvantage of the developed design is an insufficiently wide gear ratio range R=1.5…1.6, which is limited by transverse contact ratio e α
Highlights
There are several areas where application of contin uously variable transmission (CVT) ensures higher technical performance of machines
Such car manufacturers as Honda, Toyota, Ford, and Nissan have been working on the improvement of CVTs which successfully compete with automatic gearboxes
Mechanical CVTs compared with gears have large dimensions and weight, lower efficiency and rigidity of transmission ratio
Summary
There are several areas where application of contin uously variable transmission (CVT) ensures higher technical performance of machines. A CVT is a promising technology for using in transmission of hybrid cars Another relatively new area of using CVTs is wind turbines. Their drive parameters need to be adapted to wind velocity. Mechanical CVTs compared with gears have large dimensions and weight, lower efficiency and rigidity of transmission ratio. No area of the mechanical engineering contains such a number of original ideas and a variety of design solutions, including patented. 3/1 ( 93 ) 2018 a rich soil for studying the methods of design that are traditional for the mechanical engineering and the new ones, adopted from other scientific disciplines. The way an inventor passed in the search for an idea for a new CVT, design implementation of this idea usually remain unknown. The experience of the search for a new design – a pattern of the designer’s search can be more useful than the obtained result, implemented in the form of a patent
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