Investigating Effects of Direct Injection During NVO on HCCI Combustion
Effects of PreDI %
Single Cylinder Yamaha Research Engine
Compression Ratio
Objectives
 Study effects on HCCI combustion from varying:
1.
2.
3.
10.0
8.0
6.0
4.0
2.0
0.0
PreDI percent of total fuel flow
PreDI timing and duration
PI and DI durations
59.6 mm
Displacement
250 cc
Connecting Rod
116 mm
NOL
129 CAD
Work Angle
Event Angle
Laboratory Schematic
Exhaust Valve Open
123 afTDC
Building
Air
Air Heater
(3 kW)
T,P
Flame T,P
Arrester
Exhaust Valve Close
CA50 vs. Pre-DI Timing
PI Duration
(usec)
1000
500
150
10.0
8.0
6.0
4.0
2.0
69 beTDC
EVC
Air Filter
Baseline Operating Range
Muffler
T,P
Pressure
Transducer
PI
Injector
Intake
Box
Intake
Pipe
Exhaust
ChamberGate Valve
Flame
Arrester
Throttle
T,P
Gate Valve
(Emergency)
Dynamometer
Engine
Valve Timings and Details
1.6
Valve lift [mm] .
BDC
Exhaust
exTDC Induction
BDC
late-DI
SOC
pre-DI
0.8
early-DI
30
25
20
pre-DI range
0.6
15
WAex
0.4
EVO
WAin
NOL
EVC
IVO
10
IVC
0.2
5
0
0
-180
-90
0
90
180
270
360
450
Crank angle
SOI450 SOI360 bfTDC
Fig.1 Valve Timing Definition
2.5
2400 rpm
5500
5400
5300
5200
5100
5000
4900
4800
360
eTDC
EVC
380 400 420 440 460 480
Pre-DI Timing [bfTDC]
Summary
3200 rpm
3.5
3.0
2.5
2.0
1.5
1.5
1.0
1200
1.0
1200
3600
5700
5600
2800 rpm
2.0
1800
2400
3000
Speed [RPM]
150
1800
2400
3000
Speed [RPM]
3600
 Pre-DI timing can control:
1. Timing of HCCI combustion
2. Emissions produced from HCCI combustion
 Varying the pre-DI % of total fuel injection can also be used to
influence the timing of HCCI combustion and emissions
output.
 Different trends in combustion efficiency were found using
Port Injection vs. Direct Injection.
Combustion Efficiency
35
EAex
1
3.0
500
40
EAin
1.4
1.2
Expansion
3200 rpm
3.5
2100 rpm
4.0
2800 rpm
480
1000
1800 rpm
4.5
2400 rpm
380 400 420 440 460
Pre-DI Timing [bfTDC]
THC Emissions vs. Pre-DI Timing
5900
PI Duration
5800
(usec)
1500 rpm
Pre-DI/DI Baseline Map
Operating range obtained with current valve timings for both Port Injection and Direct Injection
with PreDI. This map was obtained with fixed valve timing, fixed injection timing, fixed PreDI
duration and the load varied by reducing the PI or DI duration.
540
630
Intake Valve Lift
Exhaust Valve Lift
Cylinder Pressure
Cylinder pressure [bar] .
BDC Compression fTDC
2100 rpm
4.0
(Emergency)
Rotary
Encoder
1800 rpm
4.5
Intake
Chamber
5.0
NMEP [Bar]
DI
Injector
Heated Filter
Vacuum
Line
Charge
Amplifier
1500 rpm
Pre-DI/PI Baseline Map
96
PI Combustion Efficiency vs. AFR
95
94
93
1500 rpm
92
1800 rpm
91
2100 rpm
2400 rpm
90
2800 rpm
3200 rpm
89
15
17
19
21
Air/Fuel Ratio
95
 Improving HCCI combustion by:
94
93
1500 rpm
92
1800 rpm
91
2100 rpm
2400 rpm
90
2800 rpm
3200 rpm
89
23
Future Work
DI Combustion Efficiency vs. AFR
96
Combustion Efficiency [%]
T,P
5.0
NMEP [Bar]
Condenser
Mixer
Combustion Efficiency [%]
Water
Trap
25
50
75
100
Pre-DI % of Total Fuel Injection
Effects of PreDI timing with different amounts of PI fuel. Note: the timing is retarded as PreDI
timing is retarded. Also, THC emissions reach a minimum value around 430 CAD bfTDC.
ACAP/DSP
Horiba
Bench
0
Effects of PreDI Timing
0.0
360
Injection
Chamber
100
25
50
75
100
Pre-DI % of Total Fuel Injection
eTDC
Laminar Flow
Meter
150
Effects of PreDI% on HCCI combustion. Note: the combustion timing is advanced with higher
percentages of PreDI. Also NOx emissions are more sensitive to changes in PreDI % at leaner AFR.
Int: 141, Exh: -153 aeTDC
147 bfTDC
200
0
12.0
Intake Valve Close
250
-4.0
Int: 144, Exh: 168 CAD
69 aeTDC
300
50
14.0
Intake Valve Open
AFR 19.4
AFR 21.5
-2.0
CA50 [?afTDC]
 Outline HCCI operating regime
Stroke
AFR 19.4
AFR 17.0
350
0
73.0 mm
NOx vs. Pre-DI/DI Percent
400
AFR 21.5
12.0
11.6
Bore
AFR 17.0
NOx Emissions [ppm]
 Negative Valve Overlap (NVO) – time during end of exhaust stroke
and beginning of intake stroke when both intake and exhaust valves
are closed
 PreDI – Early Direct fuel injection during negative valve overlap
 DI – Secondary Direct fuel injection during intake stroke
 PI – Port fuel injection during intake stroke
CA50 vs. Pre-DI/DI Percent
14.0
THC Emissions [ppmC]
Definitions
John Waldman, Dennis Nitz
Prof. David E. Foster
Takeru Ibara, Minoru Iida
Yamaha Motor Company
CA50 [afTDC]
Students:
Advisor:
Visiting Researchers:
Funding by:
25
15
17
19
21
Air/Fuel Ratio
23
•
•
•
•
Varying PreDI timing with shorter injection durations
Increasing coolant temperature to help expand lower load limit
Using different fuels with PreDI injection
Varying PreDI timings and durations with lower amounts of
trapped exhaust gas residuals
25
Port Injection vs. Direct injection Combustion Efficiency. Note the different trends from PI to DI.
University of Wisconsin Engine Research Center