In the field of traditional fuel vehicles, gearbox is always an unavoidable topic, and the quality of a gearbox is even used as a criterion to judge the quality of a model to some extent. Therefore, at present, major manufacturers are not soft in the field of gearbox, and have invested a lot of financial and material resources.
As manufacturers really come up with achievements in the gearbox field, consumers realize that gearboxes can have so many changes. Constantly piling up gears, the original ZF 8AT is already the most ideal gearbox in luxury cars. In addition to Mercedes-Benz 9AT, Honda and GM have come up with amazing 10AT gearboxes in the AT field; As the pioneer of dual clutch-Volkswagen Group, although Volkswagen Group announced at the 20 13 Frankfurt Motor Show that it would launch the 10 speed DSG gearbox, it has always insisted on launching and adopting the structure of 7DSG in the dual clutch gearbox put on the market. As the strongest dual clutch, PDK just added the gear superposition to the eighth gear.
Faced with more and more complicated gearboxes, many consumers began to wonder whether gearboxes have too many gears. What specific changes have been brought to the car under the multi-speed gearbox introduced by the manufacturer?
After the Millennium, ZF introduced the first generation 6HP series 6AT gearbox. With the release of such a gearbox, the multi-gear process of the gearbox has officially begun, and manufacturers are not soft on the hardware stack of the gearbox, not to mention the AT gearbox that can be continuously superimposed through planetary gear sets, even the dual-clutch gearbox that has always boasted that the gear matching is difficult has also entered this gear war.
At the 20 13 Frankfurt Motor Show, the 10 speed DSG gearbox was announced. This gearbox was born out of the seven-speed dual-clutch gearbox currently code-named DQ500. Without adding gear sets, different transmission ratios of 10 are obtained by increasing the types of locking fit between gears and gear shafts. When engineers applied this different idea to this 10-speed DSG gearbox, the upper limit of the torque that the gearbox can bear was increased to 500NM, and the fuel economy was improved by 15%.
However, in order to make this gearbox transmit power efficiently under various working conditions, the internal structure of this replacement gearbox becomes very complicated and the cost becomes very high. At the same time, the reliability of the dual clutch itself belongs to the poor quality of the total multi-gearbox type. In this highly integrated and very complex gearbox, the natural failure rate has also soared, and the transmission efficiency is not necessarily more efficient than the ordinary 7-speed DQ500 dual clutch.
The structure of the dual-clutch gearbox is mainly composed of an odd-numbered control shaft, an even-numbered control shaft, a power output shaft, a shift fork and two clutches, while the Volkswagen 10 speed DSG gearbox is equipped with a hydraulic torque converter, which not only loses transmission efficiency, but also increases the axial length of the whole gearbox. When the vehicle crawls at a low speed, the clutch needs to be engaged and disengaged frequently or in a semi-linkage state for a long time. The gear shifting frustration and clutch overheating caused by this state are far more serious than ordinary 7DCT and 8DCT, so Volkswagen finally had to give up the research and development of this 10 speed dual clutch gearbox for various objective reasons.
In the process of gearbox development, the biggest difficulty is not the technical problem, but the core patented technology mastered by some gearbox manufacturers. Compared with AT gearbox, which has formed technical barriers for a long time, it is relatively easy in the field of dual clutch, so many manufacturers have begun to work hard in the field of dual clutch, including Great Wall, Geely, BYD, Changan and SAIC, all of which have invested manpower and material resources in DCT research and development.
At present, many domestic manufacturers have invested in the field of dual-clutch gearbox, but not many can really achieve results. One of the most representative is the Great Wall's 7DCT450 gearbox, which can achieve very ideal results in hardware configuration. The maximum bearing torque is as high as 450NM, the comprehensive efficiency reaches 94.4 1%, the NVH test grade of the whole machine is A, and the design life is 300,000 kilometers.
Compared with the conservative strategy of Volkswagen 10-speed dual-clutch gearbox, with the development experience of 7DCT gearbox, Great Wall began to reach a higher peak of 9DCT, and became more compact, with its axial length reduced by 5.8mm and its average weight reduced by 2.6% due to lightweight design. On the basis of inheriting the excellent performance of the existing 7DCT gearbox, this brand-new 9DCT gearbox also adopts the built-in integrated TCU, narrow tooth width and thin synchronizer design, double pump system and self-designed technologies such as DCM and HCM, which improves the overall efficiency by 3.5%, reduces the weight by nearly 65,438+00%, shortens the load-bearing length by nearly 65,438+00%, and reportedly supports the torque to 800 Nm (.
At present, there is no specific plan and plan for mass production of 9DCT gearbox in Great Wall. However, judging from the fact that Volkswagen abandoned the 10 speed dual-clutch gearbox, it is not easy to realize mass production of high-end dual-clutch gearbox. Although it is only one more gear than the 7-speed or 8-speed dual-clutch gearbox on the market at present, the specific significance of Great Wall 9DCT gearbox is very significant in terms of actual production and market sales.
AT present, in the fierce battle for gearbox gears, in addition to CVT, manufacturers are trying to add various black technologies to the research and development of AT and DCT gearboxes. Gm Honda has 10AT, which may have great advantages over Aisin 6AT and ZF 6AT in terms of parameters, but it does not show the actual installation matching of manufacturers in terms of transmission efficiency, fuel economy, cost, post-maintenance and reaction speed.
In the process of gearbox development, more attention should be paid to the innate structure of gearbox, and the gear ratio between gears should be matched, not the number of gears. For example, the imported Volkswagen Wei Lan is equipped with a six-speed dual clutch, which is much more efficient than the domestic Magotan's seven-speed dual clutch, and the high-speed cruising speed is lower than the seven-speed; AT, Aisin 6AT horizontal front drive gearbox and ZF8AT vertical rear drive gearbox have very high comprehensive level in many aspects, which are more reliable and efficient than many 8AT, 9AT and even 10AT.
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