Promising Engineering Prototype for a New Type of Transmission
Talented Russian engineer Maxim Savinov from St. Petersburg has created a working prototype of a new type of transmission, combining the main positive features of manual transmissions and CVTs.
Prototype of the
transmission part made on a 3D printer
It took just a year for the Russian engineer to
design the prototype model and to produce it with the help of 3-D printer. The
new transmission is based on standard CVT transmissions, but the drive belt is
replaced with the drive gear. The new product is notable for the capacity to
change the gear ratio quite smoothly in the uninterrupted mode. According to Mr.
Savinov, the new transmission solution will be named RSG. In fact, RSG is an
automated transmission equipped with special cogged gears, which ensure proper
gear meshing.
Tapered shaft with
fixed gears
The RSG design is based on a tapered (cone-shaped)
shaft with gears, which are connected to each other with the help of 2 special
synchronizers. The fixed gear is located at the intersection point of
synchronizers. The secondary shaft gear moves along the tapered shaft. To
change the gear ratio, a special mechanism moves the gear wheel of the secondary
shaft and rolls it from the fixed gear of the tapered shaft to the other fixed
gear, thus changing the gear ratio smoothly and continuously. In terms of
efficiency and speed, this mechanism is comparable to DSG transmissions.
Two secondary shafts
simulating the operation of 7-speed transmission
In terms of design, the RSG prototype is not
more complicated than the classic CVT transmission, and is much simpler than
dual-clutch gearboxes. The efficiency of this innovative product reaches up to
96 %, ensuring a significant increase in the car dynamics (up to 30 %) in
comparison to cars equipped with manual transmissions. This statement may be
disputable; presumably, Mr. Savinov took the average time of gear shifting in
manual transmissions, multiplied this number by 4 (direct gear), and the
product was subtracted from some conditional time of acceleration to 100 km/h.
In this case, significant increase in acceleration dynamics can be achieved
only on more powerful cars.
The new transmission solution still has some drawbacks. Complexity of the rear gear implementation, large overall dimensions of the transmission, insufficient load capacity of gear meshing (one and a half times less than in manual transmissions) and low kinematic range (approximately 3-3,5) are the main points to be improved in the RSG development. Currently, the transmission turns out to be unbalanced – it is focused either on the speed of operation or on the power, but it is a challenging task to achieve an efficient combination of these parameters. In this regard, CVTs seem much more comfortable. The problem of a limited power range can be solved if gears are connected in a successive order. Maxim Savinov has got development estimates for the RSG adaptation in the Russian cars (GAZelle) – the use of a pair of secondary shafts makes it possible to achieve more or less acceptable power range.
Maxim Savinov, the
creator of RSG transmission
Maxim Savinov won a grant “Start-1” from the Russian Innovation Promotion Fund for further development of the RSG transmission. The funds were spent on the engineering study, development of prototypes and obtaining of patent rights (already issued in Russia, and applications were sent to China, USA, Europe, Japan, Korea and India). At this stage, Maxim Savinov is counting on receiving a second grant. He created more efficient technical solutions and performed preliminary calculations for development of the RSG version for KAMAZ.
It should be noted that design peculiarities of the RSG transmission make it a good option for electric vehicles, which have lower requirements on gear ratios if compared to cars with internal combustion engines.
