RV-reducer, its full name is Rotate Vector Reducer. It is also named 2KV-reducer in China.

In early 1930s’, planet-cycloid reducer is invented by a German mechanican Lorentz Brown. RV-transmission is a kind of new way of driving which is developed from planet-cycloid transmission. Usually a RV-reducer is composed by the first step of a planetary-gear transmission and the last step of a planet-cycloid reducer. It overcame some original defects of planet-cyloid reducer, and at same time it had some excellent advantages such as compact structure, large gear range, low noise, high efficiency, long life-time, smooth transmission, high precision, etc. Because of these reasons, RV-reducer is widely used in industrial area, like industrial robot and machine tool. With the development of machinery industry and the wide using of industrial robot, RV-reducer, as the core part of industrial robot, is getting increasing attention. Comparing with traditional planet-cycloid reducer, RV-reducer is more appropriately to use for heavy load working. Most companies would like to used RV-reducer for their industrial robots’ joints because nowadays mostly the robot works in taught conditions, and loading heavy weight is one of their main function.

Japan is the leader in this area. Chinese companies still need to spending more time and investment to do research. Nowadays the RV-reducers in global market mostly come from two Japanese companies, Nabtesco and Harmonic Drive. More than 60% precision speed reduction device of industrial robot is produced by Harmonic Drive. Especially in the area for middle loading and heavy loading robots, more than 90% RV-reducer is produced by Harmonic Drive.

Only few countries in the world are able to manufacture the RV-reducer independently. During The 12th Five-Year Guild-line (2011-2015), Chinese government regarded developing RV-reducer as one of the technical problem that need to be solved urgently. During last few years, many Chinese universities and scientific research organizations made some progress in the theory but not able to apply it in product. And the key of producing RV-reducer is using over-positioning in the processing of manufacturing to ensure the RV-reducer could be able to transfer large torque, keep function well under overloaded impact, and meets the excepted design lifetime in ensuring accuracy condition. And it makes producing RV-reducer need very high machining precision. Last few years Chinese companies made increasing progress in theory and it is good news for Chinese machinery industry. There might be one day that Chinese independent Ramp;D RV-reducer earn a place in global market. But people need to know that researching RV-reducer is a difficult topic. And it makes lot of companies finch. According to the statistical data from GRII, only 13 of 353 Chinese robot companies did research relative to reducer. And only 5 of them was developing RV-reducer. No doubt that more attention should be given to Chinese independent RV-reducer investment. Otherwise it might be the weakness of Chinese robot industry.

This degree project aims to letting students to summarize and apply the knowledge they learned during their bachelor education. It makes students take part in the processing of designing RV-reducer with the guidance of their supervisor and it makes students learn the structure of RV-reducer deeply.

2. 研究的基本内容与方案

2.1 Substance

2.1.1 Development status of RV-reducer