Date post: | 03-Apr-2018 |
Category: |
Documents |
Upload: | ssp-villalba |
View: | 242 times |
Download: | 1 times |
of 19
7/28/2019 PPT 4 Rotary Engine
1/19
The Rotary (Wankel) Engine
Ben Larson
Peter ShrefflerScott Steinmetz
7/28/2019 PPT 4 Rotary Engine
2/19
7/28/2019 PPT 4 Rotary Engine
3/19
History
Popularity for the rotary powered vehicles
increased rapidly until the gas crisis in the mid 70s
Rotary engines were not very fuel efficient compared to
piston engines
Strict emissions standards could not be met with current
rotary technology
These two factors severely hurt the sale and
development of rotary engines
Mazda was the only car company that continued to
produce cars with rotary engines through the 90s
7/28/2019 PPT 4 Rotary Engine
4/19
History
This graph demonstrates the rise and decline of the rotary engines
popularity through the mid to late 90s
7/28/2019 PPT 4 Rotary Engine
5/19
Automotive Success with Rotaries
In 1991, the Mazda787B won the 24-hourLe Mans endurancerace Rotary engines were
then banned from the C2circuit
The RX-8 is able to
produce 238 hp from its1.3L engine and withgood gas mileage andfavorable emissions
7/28/2019 PPT 4 Rotary Engine
6/19
Intake
Begins when apex
passes intake port
Increase in chamber
volume Creates low pressure
zone
Pulls in Fuel/Air
mixture
Completes when next
apex passes intake
port
7/28/2019 PPT 4 Rotary Engine
7/19
Compression
Begins after intake
Volume of chamber
decreases
Fuel/Air mixturecompressed
Chamber compresses
to its minimum size
7/28/2019 PPT 4 Rotary Engine
8/19
Combustion
Spark plugs ignite mixture
Two spark plugs to
maximize amount of fuel
ignited
Causes rapid chamber
expansion
Turns rotor which
produces work output on
shaft Power stroke continues
until apex passes exhaust
port.
7/28/2019 PPT 4 Rotary Engine
9/19
Exhaust
Chamber decreases in
size
Forces combustion bi-
products out theexhaust port
Continues until next
apex passes exhaust
port. Entire cycle repeats
7/28/2019 PPT 4 Rotary Engine
10/19
The Cycle
Rotor mounted
eccentrically on shaft
One rotation of rotor
provides three rotationsof shaft
Spark plugs fire 3 times
per rotor revolution
One rotation of shaft foreach firing of spark plugs
7/28/2019 PPT 4 Rotary Engine
11/19
Port Timing
Intake ports shape and size can be altered tochange engine timing
Limited by oil and coolant track
Overlap is when intake port opens before exhaustport closes
Support at least 50% of apex seal
Street ports
Moved up to delay intake closing
Moved out to open intake earlier
Limited overlap and with reasonable limits of oil tracks
Racing ports
Very close to oil tracks
Reduced engine life
Sometimes large overlap
Increased power at high RPM
Decreased power at low RPM
7/28/2019 PPT 4 Rotary Engine
12/19
Advantages
Vibration
No unbalanced reciprocating masses
Power/Weight
For similar displacements, rotaries are generally 30%lighter and produce twice as much power
Simplicity
Contain half as many moving parts
Have no connecting rods, crankshaft, or valve trains
7/28/2019 PPT 4 Rotary Engine
13/19
Disadvantages
Fuel Efficiency and Emission
The shape of the combustion chamber, which is long
instead of small and concentrated, makes the combustion
travel longer than a piston engine
Due to the longer combustion chamber, the amount of
unburned fuel is higher which is released into the
environment
Cost
The lack of infrastructure and development for the rotaryengine has caused their production and maintenance
costs generally to be more
7/28/2019 PPT 4 Rotary Engine
14/19
Future Trends: Hydrogen
Highly Flammable
Production Energy from
Crude Oil, Coal, Natural Gas, and Nuclear
Combustion Results in Water and NOx
Energy Density
High Per Unit Mass
Low Per Unit Volume
7/28/2019 PPT 4 Rotary Engine
15/19
Challenges of Hydrogen
Storage
Requires Large Tank
Combustion
High Temperatures
Pre-ignition causes backfiring, excessive wear
NOx formation
Injection Components Low temp rubber seals
7/28/2019 PPT 4 Rotary Engine
16/19
Rotary Hydrogen Solutions
Low Operating Temperature
No Backfiring
Very Low Levels of NOx
Separate Intake & Combustion Chambers
Rubber Injector Seals Exposed Only to Intake
7/28/2019 PPT 4 Rotary Engine
17/19
Hydrogen Rotary Timeline
1991HR-X
1993HR-X2
1997Demio FC-EV
2001
Premacy FC-EV
2004
RX-8 RE
2006
Mazda5 RE
7/28/2019 PPT 4 Rotary Engine
18/19
RENESIS Hydrogen Rotary
Dual Fuel
Switches from Hydrogen to Gasoline
Direct Injection
Electronically Controlled
Extended Seal Life
Twin Injectors
Increased Injection Volume
Control Valve
Adjusts pressure of injected hydrogen
7/28/2019 PPT 4 Rotary Engine
19/19
Hydrogen Conclusion
Cleaner Burning
Water, Minimum NOx
Rotary Engine Solves Combustion Issues
Low Temperature
Separate Induction and Combustion Chambers
Dual Fuel Mazda5 RE
Practical For Gas-Hydrogen Transition