Honda Announces New Dual Clutch Transmission for Large-displacement Sport Bikes and CV-Matic Automatic Transmission for Cub-style Scooters
|Honda Dual Clutch Transmission for motorcycles. Click to enlarge.|
Honda has developed two new transmissions for its motorcycle product lines. The new Dual Clutch Transmission is the first fully automatic motorcycle dual clutch transmission for large-displacement sport bikes. The new CV-Matic automatic transmission can be used in combination with Cub-style engines.
Dual Clutch Transmission. The Dual Clutch Transmission provides riders sporty riding enjoyment with easy operation, while its superior transmission efficiency delivers fuel economy equal to or better than a conventional manual transmission. A new VFR large-displacement sport bike equipped with the new transmission will be released in Europe and North America in 2010, with sales to commence in Japan at a later date.
This first motorcycle dual clutch transmission features a light, compact design that allows it to be combined with existing engines without substantial layout modification. Further, the new transmission delivers the precise acceleration control riders require thanks to electronic control technology that helps ensure smooth, seamless gear changes.
In order to respond to rider demands in a broad range of situations, the transmission is equipped with three operating modes, two full-auto modes (D-mode for regular operation and S-mode for sporty riding); and a 6-speed manual mode, which delivers the same shift feel as a manual transmission.
Honda intends to gradually expand the deployment of the new transmission to more and more of its large-displacement motorcycles, particularly sports models destined for use in developed countries.
|Honda DCT structural diagram. Click to enlarge.|
The Dual Clutch Transmission main shaft consists of two coaxial shafts: an inner shaft for odd-numbered gears (1st, 3rd, 5th) and an outer shaft for even-numbered gears (2nd, 4th, 6th). Both the inner and outer shafts are connected to mutually independent clutches, which operate alternately to achieve fast, seamless gear changes with constant, uninterrupted power application.
For example, when changing from 1st to 2nd gear, the computer detects the up-shift and engages 2nd gear, then releases the 1st-gear clutch while engaging the 2nd-gear clutch to achieve a seamless gear change.
The in-line layout of these two clutches (patent pending) along the transmission axle, together with the hydraulic control piston installed on the inner face of the clutch disc, results in a more compact configuration which also minimizes lateral intrusions in the direction of the transversely mounted engine.
A more compact and lightweight construction was achieved by concentrating the linear solenoid valves and other clutch control devices and hydraulic circuits under the clutch cover. Two control devices are independently used for optimized control of the two clutches, achieving smoother acceleration and shock-free gear changes.
Much like a conventional manual transmission, the shift mechanism uses a rotating shift drum to actuate the shifter. However, unlike conventional transmissions, the shift drum is motor-driven for optimized control. Alternating operation of the two clutches is performed using this single shift drum. (Patent pending.) Optimized shift scheduling achieves fuel economy equal to or better than that of a fully manual transmission, enabling Dual Clutch Transmission to deliver both sporty riding and environmental performance combined.
|The CV-Matic. Click to enlarge.|
CV-Matic. In 1958, Honda introduced the Super Cub C100 as a harbinger of the automatic transmission era. The Cub came equipped with an automatic centrifugal clutch mechanism, which enabled the rider to shift gears without operating the clutch while riding.
Currently, motorcycles see widespread use in developing countries, particularly in Asia. Automatic transmissions are widely used, especially on scooters. Against this background, demands are increasing for the introduction of a fully automatic transmission to the Super Cub series, which continue to be popular due to their high utility and durability.
The new CV-Matic further enhances the practicality and convenience of the Cub-type models. The new system will be available with Cub-style scooters to be released in the ASEAN region starting in 2010.
Honda’s newly developed CV-Matic is a compact version of its standard V-belt CVT, and for the first time makes it possible to build a V-belt CVT within the crankcase of a compact motorcycle engine. Thanks to its compact design, the new engine and drivetrain can be mounted in the chassis without major changes in layout, thus providing greater versatility and durability than conventional scooters. It can even fit in a Super Cub-style frame, thereby expanding this new drive system’s range of commuter applications.
|CV-Matic structure. Click to enlarge.|
The CV-Matic features a new cooling system developed on the basis of Honda’s small-motorcycle automatic transmission technology. CVT V-belts are subject to extremely high temperatures due to heat produced by the friction between the belt and pulleys, as well as from the engine oil. Since the CV-Matic system features a shorter distance between pulleys, and that the mechanism itself is located inside the crankcase, cooling performance inside the transmission itself is even more important than with previous V-belt CVTs.
The CV-Matic cooling system’s baffles and ribs have been specially designed to permit airflow to reach into every nook and cranny of the transmission interior, thereby providing optimal cooling capability with its patent-pending construction. A compact oil cooler mounted on the cylinder block also receives ample airflow when the bike is ridden. Actively cooling the transmission and adjacent oil reservoir helps keep transmission temperatures down, and effective management of cooling performance also greatly contributes to transmission system durability.
Finally, with both the cooling intake and exhaust ports located on the top of the transmission housing, the motorcycle can be operated even on flooded roads as long as the duct openings remain above water.
Whereas existing V-belt CVTs employ a dry clutch, the CV-Matic features a wet clutch similar to that used on Super Cub and Honda ATV models to ensure durability similar to that of Super Cub models.