Previous we discussed on the SKYACTIV Gasoline engine and Diesel engine, that how an engine works and what were its merits and de-merits. Let’s explore the transmission of SKYACTIV Technology. Today we learn perfect control of transmission with the help of Ideal Transmission.
Here we go…….
Ideal Transmission for Perfect Control
Transmission is critical not only to fuel efficiency improvement but also to a cars driving performance. The “ideal transmission” that gives you perfect control over your car. With this concept, we have developed a pair of transmission systems that promise precise handling as well as improved fuel efficiency.
Thanks to an expanded lockup range of more than 80%, the SKYACTIV-DRIVE automatic transmission gives you the direct feel of a manual transmission. The SKYACTIV-MT manual transmission, with its class-leading light weight, ensures a crisp feel when shifting.
We have two different types of Transmission as mentioned below.
A new-generation highly-efficient automatic transmission that achieves excellent torque transfer efficiency through a wider lock-up range and features the best attributes of all transmission types.
- Combines all the advantages of conventional automatic transmissions, continuously variable transmissions, and dual clutch transmissions
- A dramatically widened lock-up range improves torque transfer efficiency and realizes a direct driving feel that is equivalent to a manual transmission
- A 4-to-7 percent improvement in fuel economy compared to the current transmission
All the Advantages of Conventional Step CVT (continuously variable transmission), Dual Clutch, and Step AT (Automatic transmissions).
Automatic transmissions (AT) can be categorized into three types:
- CVT: generates various gear reduction ratios with a pair of pulleys
- Dual Clutch: utilizes 2 separate clutches for odd and even gear sets.
- Conventional AT: generates various gear reduction ratios with planetary gear sets
The key requirements for ATs are “good fuel economy”, “quick start-up” (including hill climbing), “direct feel” and “smooth shifting”.
The table below shows the drawbacks and advantages of each transmission.
A new-generation manual transmission with a light shift feel, compact size and significantly reduced weight.
- A light and crisp shift feel like that of a sports car
- Compact size and reduced weight
Technical Aims & Concept
North American and Japanese markets always prefer Automatic transmission Whereas Manual Transmission is dominating in Europe. To meet global demand, two types of MT (“Large” and “Mid” sizes) have been newly developed. The development concept was to create a “light and compact MT with improved shift feel and better fuel economy”. The goal was to achieve an MX-5-like sporty and brisk shift feel.
For a quick shift feel, both a short shift-lever stroke and light shift effort had to be achieved. By pursuing the ideal structure of manual transmissions, 16% at maximum of weight reduction was achieved. Furthermore, internal friction losses were significantly reduced to achieve a 1% improvement in fuel economy.
Quick and Crisp Shift Feel
To achieve lighter shift effort with a short shift lever stroke, the lever ratio must be increased. However, a larger lever ratio reduces the internal stroke. To achieve precise synchronizer and torque transmission even with a short internal stroke, a small module spline is used.
Also, the shift effort gradually reduces through the stroke, providing reassuring resistance as the lever is first pushed, then getting lighter so it feels as if the shift lever is automatically moving into gear. With the current shift lever, shift effort in the select direction (right-left direction) increases with the movement of the shift lever, but with the new shift lever, a stable shift effort is achieved. Binding is minimized when shifting diagonally.
Light and Compact MT
Since the structure of an MT is relatively simple, completely new ideas and logical thinking are required to achieve further weight reduction and higher efficiency.
The triple-shafted gear train with a common gear for 2nd and 3rd was selected from approximately 30 different configurations due to its potential to achieve lightness, light shift effort, high efficiency, and a wide gear ratio. Based on this selection, the lightest structural specifications were selected from over 10,000 alternatives. By reviewing the function of each component, commonization of the 1st and reverse gears was newly adopted.
This enabled the length of the secondary shaft to be reduced by 20%. A common 1st and reverse gear made possible the removal of the reverse idle shaft. As a result, by reexamining gear configurations, the number of components decreased and the gear train weight was reduced by roughly 3kg.