i-stop CONTROL [SKYACTIV-G 2.0]

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Outline

•  When the vehicle is stopped such as at a stop light, the i-stop control stops/starts the engine automatically to improve fuel economy and reduce exhaust gas and idling noise.
•  The PCM determines whether to permit/inhibit i-stop control based on the signal from each input part and CAN communication.
•  The i-stop control includes the engine stop control, engine restart control, electric AT oil pump driver control, and hill launch assist functions.

Control Table

Control name

Control outline
Engine stop control
•  The engine is stopped when the i-stop (engine stop control) conditions are met.
Engine restart control
•  The engine restarts when the i-stop (engine restart control) conditions are met.
Electric AT oil pump driver control
•  Drives the electric AT oil pump to assure line pressure during an engine stop by the i-stop control. (See OIL PUMP [ET6A-EL, ET6AX-EL].)
Hill launch assist function
•  Controls the traction control solenoid valve in the electronically controlled brake unit to maintain or decrease brake fluid pressure. (See ELECTRONICALLY CONTROLLED BRAKE SYSTEM.)


Block Diagram

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*1  :TCM, Electronically controlled brake unit, BCM, Instrument cluster, EPS control module, ESU, Dash-electrical supply unit, SAS control module

Operation


Engine stop control

i-stop (engine-stop control) permit condition
•  The conditions to stop the engine by the i-stop control are as follows:

Determination module

Determination item

Determination condition
PCM
Vehicle speed
20 km/h {12 mph} or less
Brake pedal
Brake pedal is depressed while in D position
However, no brake pedal conditions during Mazda Radar Cruise Control with Stop & Go function (MRCC with Stop & Go function) and Cruising & Traffic Support (CTS) operation*1
Brake fluid pressure
Brake fluid pressure is 1.35 MPa {13.8 kgf/cm2, 196 psi} or more while in D position (perform correction according to vehicle inclination angle)
However, no brake fluid pressure conditions during Mazda Radar Cruise Control with Stop & Go function (MRCC with Stop & Go function) and Cruising & Traffic Support (CTS) operation*1
Brake stroke
3 mm {0.1 in} or more
Panic brake
Not operating
ABS control
Not operating
Accelerator pedal
Released
Vehicle conditions
Vehicle is stopped in D position*2
Steering speed
15 deg/s or less
Steering angle
Within 65° of center to left and right
(After EPS control module learns center value)
Steering torque
1.1 N·m {11 kgf·cm, 9.7 in·lbf} or less
i-stop OFF switch
OFF
Vehicle speed history
(After engine started and driven once)
3 km/h {2 mph} or more
Door (driver's side)
Closed
Hood
Closed *3
Vehicle inclination angle
Within ±7° when level (LON_ACCL_C: within ±0.121 G)
Seat belt (driver's side)
Fastened*4
Steering angle sensor initial setting
Completed
Engine coolant temperature
30—110 °C {86—230 °F}
Intake air temperature
100 °C {212 °F} or less
Altitude
2,000 m or less
System condition
i-stop related part DTCs are not recorded
Mazda M Hybrid battery voltage
20 V or more
Mazda M Hybrid battery condition
30 % or more
Mazda M Hybrid battery temperature
120 °C {248 °F} or less
ISG temperature
120 °C {248 °F} or less
Brake coordinated control end
Completed
Deceleration request
MRCC in operation
Drive selection switch
Other than SPORT mode
BCM
+B (ROOM fuse) input
Yes
IG1 input
Yes
ACC input
Yes
IG1 output
Yes
ACC output
Yes
BCM
Push button
Not pressed
Door (all)
Closed
Liftgate
Closed
Seat belt (driver's side)
Fastened*4
Engine start
Engine was started by operating push button with key inside cabin (engine started first time)
Engine rotation speed
300 rpm or more is maintained after engine started
System condition
i-stop related part DTCs are not recorded
TCM
TCM detection condition
All met (I-Stop_EST: On)
Panic stop
Brake pedal was not depressed suddenly within 4 s
TFT
20―117 °C {68—242 °F}
Gear position
Not in 2nd gear fixed mode
System condition
i-stop related part DTCs are not recorded
Dash-electrical supply unit
Dash-electrical supply unit determination condition
•  All met
(STOP_ST: Available)
Cabin temperature
Difference between target cabin temperature and actual cabin temperature is a certain value or less
(Cabin temperature control by A/C is normally performed)
A/C temperature
Setting other than MAX/MIN
Ambient temperature
-10―50 °C {14—122 °F}
Cold condition
Ambient temperature is 4 °C {39 °F} or more or evaporator temperature is 12 °C {54 °F} or less
Front defroster switch
OFF
Electronically controlled brake unit
Operation request from PCM
Hill Launch Assist (HLA) control request signal from PCM is received
Vehicle inclination angle
Inclination is within ±6° with shift positioned in D/R or N/P (LON_ACCL_C: within ±0.104 G)
Wheel speed (4 wheels)
0 km/h {0 mph}
Brake pedal
Brake pedal is depressed
Brake fluid pressure
Approx. 0.45 MPa {4.6 kgf/cm2, 65 psi} or more
Accelerator pedal
Released
System condition
i-stop related part DTCs are not recorded

*1  :During Mazda Radar Cruise Control with Stop & Go function (MRCC with Stop & Go function) and Cruising & Traffic Support (CTS) operation, the engine is stopped by i-stop control without having to depress the brake pedal.
*2  :After the vehicle is stopped, the engine stops if the gear is shifted to N position. In addition, if the gear is shifted to P position after the vehicle is stopped in D position, the engine stop condition by the i-stop control is maintained.
*3  :If the engine is started with the hood open, i-stop is inhibited until the engine is stopped.
*4  :If the seat belt is unfastened while the vehicle is stopped, i-stop is inhibited until a vehicle speed record is input once.
i-stop (engine stop control)
•  When the i-stop (engine stop control) permit conditions are met, the PCM stops the engine based on the following controls:
―  Fuel injection control (fuel cut)
•  Engine speed is reduced by the fuel cut.
―  Drive-by-wire control (throttle valve open/closed)
•  By adjusting the throttle valve opening angle, the engine speed is reduced and the pumping loss is used to stop the engine.
―  Electric variable valve timing control (intake valve timing retard)
•  Intake valve timing retard is performed for engine restart by i-stop control.
―  Generator output control (generator load)
•  Engine speed is reduced by lowering the generator load.


Engine restart control

i-stop (engine restart control) conditions
•  Conditions for restarting the engine during i-stop control (engine stopped) are as follows:

Detection module

Detection item

Determination conditions
PCM
Vehicle speed If i-stop control is performed (engine stop control) while vehicle is stopped
1 km/h {0.6 mph} or more
Vehicle speed If i-stop control is performed (engine stop control) while driving
30 km/h {19 mph} or more
Brake pedal
•  Brake pedal is released → depressed while in P or N position
•  Brake pedal is released while in D position and AUTOHOLD is not operating
•  However, no brake pedal conditions during Mazda Radar Cruise Control with Stop & Go function (MRCC with Stop & Go function) and Cruising & Traffic Support (CTS) operation*1
Brake stroke
2.5mm {0.098 in} or less at D position
Panic brake
Operating
ABS control
Operating
Other system
Vehicle roll prevention function is not operating at D position
Accelerator pedal
Accelerator pedal is depressed while in D or M or N or P position
Steering torque
2.8 N·m {29 kgf·cm, 25 in·lbf} or more while in D position
Steering angle
±20° or more
Steering angle sensor initial setting
Learning reset
Shift operation
Operated from P or N position to D position
Operated R position
i-stop OFF switch
ON
Driver not seated
•  All the following conditions are met:
―  Seat belt (driver's side): Not fastened
―  Door (driver's side): Open
―  Hood: Open
Hood
Open
Engine stop period by i-stop
120 s or more
Engine coolant temperature
55 °C {131 °F} or less
System condition
An i-stop related part DTC is recorded
MRCC deceleration request
MRCC in operation: -1.5 m/s2 or more
Drive selection switch
SPORT mode
Mazda M Hybrid battery voltage
16 V or less
Mazda M Hybrid battery condition
25 % or less
Mazda M Hybrid battery temperature
60 °C {140 °F} or less
BCM
+B (ROOM fuse) input
No
Remote transmitter authorization
When engine restart by remote transmitter authorization is requested
•  Any door is open without remote transmitter left in vehicle
•  Remote transmitter is outside of vehicle after any door is opened
System condition
An i-stop related part DTC is recorded
TCM
Gear position
In 2nd gear fixed mode
TFT
20 °C {68 °F} or less, or 117°C {243 °F} or more
Vehicle speed
3 km/h {2 mph} or more
System condition
An i-stop related part DTC is recorded
Dash-electrical supply unit
A/C request
Yes
A/C set temperature
Set to MAX or MIN
Front defroster switch
ON
Electronically controlled brake unit
System condition
An i-stop related part DTC is recorded

*1  :During Mazda Radar Cruise Control with Stop & Go function (MRCC with Stop & Go function) and Cruising & Traffic Support (CTS) operation, the engine is not restarted by i-stop control even if the brake pedal is released.
i-stop (engine restart control)
•  When the i-stop (engine restart control) conditions are met, the PCM restarts the engine by the following controls:
―  Fuel injection control (from first time, fuel injection to specific cylinders (expansion stroke)
•  Fuel is injected to cylinders which are determined to be stopped at the expansion stroke. During i-stop control (engine stop), cylinders are identified based on the signal from the crankshaft position sensor and fuel injection is enabled to those cylinders which are identified first as being stopped in the expansion stroke.
―  DC-DC converter control
•  When the engine is restarted by the i-stop control, the battery voltage is decreased to operate the starter by supplying power from the battery. When the starter operates, the supply voltage for electronic devices is increased by the DC-DC converter.