Transcript AUTOMATIC TRANSMISSION - Free Downalod Project,Study

AUTOMATIC TRANSMISSION
Presented By,
Muhammed Riyas
S7MB
NO:103
Guided By,
Gopinathan.V
Asst:Prof
Dept of Mechanical Engg
Introduction
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Device which changes gear ratios automatically
Deliver maximum efficiency
Difference between automatic and manual transmission
Easier to drive because they do not have a clutch pedal or
gearshift lever
• There are two type of automatic transmissions
CLASSIFICATION
 AUTOMATIC
TRANSMISSIONS
USING PLANETARY
GEARS
CONTINUOUSLY
VARIABLE
TRANSMISSION(CVT)
AUTOMATIC TRANSMISSIONS
USING PLANETARY GEARS
Components
• PLANETARY GEAR
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SYSTEM
TORQUE CONVERTER
HYDRAULIC SYSTEM
GOVERNOR
COMPUTER
CONTROLS
1. Sun gear 2. Planet gear 3. Ring gear 4.
Planetary carrier
PLANETARY GEAR SYSTEM
PLANETARY GEAR SYSTEM (SIDE VIEW)
HOW PLANETARY GEARS WORK
• Power transfer can only take place when one of the members is
held at rest or if two of the members are locked.
Input
Output
Stationary
Calculation
Gear Ratio
A
Sun (S)
Planet Carrier (C)
Ring (R)
1 + R/S
3.4:1
B
Planet Carrier (C)
Ring (R)
Sun (S)
1 / (1 + S/R)
0.71:1
C
Sun (S)
Ring (R)
Planet Carrier (C)
-R/S
-2.4:1
Gear
Input
Output
Fixed
Gear Ratio
1st
30-tooth sun
72-tooth ring
Planet carrier
2.4:1
30-tooth sun
Planet carrier
36-tooth sun
2.2:1
Planet carrier
72-tooth ring
36-tooth sun
0.67:1
Total 2nd
1.47:1
2nd
3rd
30- and 36-tooth
suns
72-tooth ring
OD
Planet carrier
72-tooth ring
36-tooth sun
0.67:1
Reverse
36-tooth sun
72-tooth ring
Planet carrier
-2.0:1
1.0:1
TORQUE CONVERTOR
• takes the place of the clutch
found on standard shift vehicles
• large doughnut shaped device that is mounted
between the engine and the transmission
• it uses oil or transmission fluid to transmit power
• three internal elements that work together
to transmit power to the transmission.
TORQUE CONVERTOR
THE HYDRAULIC SYSTEM
• complex maze of passages and tubes that sends transmission
fluid under under pressure to all parts of the transmission
and torque converter.
• Transmission fluid serves in shift control, general lubrication
and transmission cooling.
• Keeps the transmission at normal operating temperature
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OIL PUMP
VALVE BODY
SHIFT VALVES
BANDS
Oil Pump
• Produce all the oil pressure that is
required in the transmission
• The oil is then sent, under
pressure to the pressure regulator,
the valve body and the rest of the
components, as required.
Gear pump
Valve Body
• The brain of the automatic
transmission
• Contains a maze of channels
and passages that direct
hydraulic fluid to the
numerous valves
• These valves activate the
appropriate clutch pack or
band servo to smoothly shift
to the appropriate gear for
each driving situation.
Shift Valves
• Supply hydraulic pressure to
the clutches and bands to
engage each gear
• Determines when to shift from
one gear to the next
• The 1 to 2 shift valves
determines when to shift from
first to second gear.
Band
• A band is a steel strap with
friction material bonded to the
inside surface.
GOVERNER
• provides the inputs that tell the
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transmission when to shift
connected to the output shaft
and regulates hydraulic pressure
based on vehicle speed
COMPUTER CONTROLLS
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Detect such things as throttle position, vehicle speed,
engine speed, engine load,etc. to control exact shift
points
Downshift automatically when going downhill, to
control speed and reduce wear on the brakes.
Up shift when braking on a slippery surface to reduce
the braking torque applied by the engine.
Inhibit the Up shift when going into a turn on a
winding road.
CONCLUSION
Automatic transmissions contain mechanical systems,
hydraulic systems, electrical systems and computer controls,
all working together in perfect harmony
THANK YOU