Compared to manual
transmissions, modern automatic transmissions enhance driving comfort and also
save on fuel, which is because they independently determine the point at which
the engine runs most efficiently. In series-produced vehicles, there are now up
to nine gears to choose from.
These modern transmissions are
equipped with a great deal of digital intelligence so that they are always
capable of identifying the engine’s ideal operating point. Bosch supplies the
control units, sensors, and solenoid valves for all major types of
transmissions. The control unit is a high-tech miniature computer that enables
the complex operation of different types of automatic transmissions. The
processing capacity of a modern transmission control unit is an incredible 160
times more powerful than that of the computer used for the first lunar flight.
This was stated in a press release issued by Bosch.
There are a wide range of
automatic transmissions featuring Bosch controls. These include:
Traditional automatic: The tried-and-tested transmission shifts
automatically using programmes stored in the control unit. In many cars, the
driver also has the option of shifting to another gear with switches on the
steering wheel, which prevents shifting errors. The traditional automatic often
has six gears, though some ultra-efficient versions now feature up to nine
Automated manual transmission: This type of transmission combines
the best of an automatic and manual transmission. It offers the comfort and
convenience of an automatic with the individual control of a manual
transmission. The clutch remains open when idle and only uses energy when being
closed. This transmission therefore also saves fuel, reducing CO2 emissions in
Dual-clutch transmission: This particular model actually comprises
two separate transmissions. One is used for the even gear set and the other for
the odd. Two clutches shift back and forth between both transmissions within a
split second, allowing for especially swift gear changes. The complex
coordination in a dual-clutch transmission is only made possible by a
sophisticated transmission control system with powerful processing such as that
offered by Bosch.
CVT: CVT (continuously variable transmission) is an automatic
without any fixed shifting point, which completely eliminates shifting response
delays. As a result, the driver can accelerate without any interruption as the
driving force is available at all times. The vehicle does not have to shift
back and forth between fixed shifting points – a feature that provides extra
driving comfort, especially when going up an incline. CVT is widespread in Asia
and North America.
eClutch: The Bosch eClutch introduces the comfort of an automatic to
a manual transmission in a cost-effective way. Thanks to this innovative
technology, drivers can go into first gear simply by stepping on the gas pedal.
The eClutch automates the clutch only, not the transmission. The clutch pedal
transmits an electric signal to an actuator, which decouples the clutch. This
affordable alternative to a fully automatic transmission is especially useful
for drivers of compact cars that frequently find themselves in stop-and-go
traffic within urban settings. The eClutch also represents an appealing option
for drivers in emerging markets.
Thanks to the eClutch, manual
transmissions can also benefit from the fuel-saving coasting function, which is
otherwise only possible with modern automatic transmissions. Coasting expands
on the well-known start-stop function and enables additional fuel savings of up
to ten percent. When this function is used, the engine not only switches off at
traffic lights, but also while the vehicle is moving.
Bosch is driving forward
connecting transmissions with the latest available navigation information.
Navigation systems know the lay of the land and can transmit this data to the
automatic transmission, which, in turn, can shift into neutral and use the
residual momentum if city limits are coming up after a long bend, for example.
This even more intelligent automatic transmission with electronic horizon can
provide additional double-digit fuel savings.