Quote:
Originally Posted by MadTiger This is some serious tech, no matter how mild it might be but its functional and it works! Thank you! I have a follow up question.
I have heard in one of the car reviews that when the engine auto start / stop kicks in while stopped at a stop light for prolonged time the ISG runs the AC compressor without starting the engine when cabin temperature increases? Is that true? |
Quote:
Originally Posted by Leoshashi I'll make a detailed post on the functioning of Smart Hybrid soon. A lot of wrong info has been circulated in the media by these self proclaimed experts. |
As promised, here I am with a detailed description of the Smart Hybrid system. There is a lot of nonsense and misinformation circulated in the media. Have a look at this video:
The Presenter talks about something being mounted on Flywheel and what not!
Even our official review couldn't escape from the misinformation. Two excerpts from our official review of Ciaz and Ertiga. Knowing how TeamBHP reviews work, I'm sure the origin of this misinformation is presentation by Maruti during media drives itself.
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Originally Posted by Aditya Driving the 1.5L Petrol MT Smart Hybrid system:
The ISG replaces both, the conventional starter and alternator. |
Quote:
Originally Posted by blackwasp Driving the 1.5L Petrol MT Smart Hybrid System:
The ISG replaces both, the conventional starter and alternator. |
What's true:
-Conventional Starter motor is very much present.
-In simple words, ISG is a device which has dual function-Motoring as well as Generation. It's belt driven and connected to Pulley which is in turn connected to crankshaft.
-Starting- To simplify, when push button start is pressed, the usual cranking sound can be heard, and that's when Conventional starter motor is at work. When car shuts down automatically by Auto Stop function, it resumes silently, and that's when ISG revives the engine using its belt drive. This is why it resumes silently without making any noise.
Techincal Elaboration Description of SHVS System
The SHVS system comprises the ISG, ECM and a variety of sensors, etc. In addition to a deceleration energy regenerating function (1) that utilizes the ISG to generate power mainly during deceleration, the SHVS system is equipped with an engine power assist function (2) that acts as an auxiliary power source for the engine when the accelerator is depressed, and a starter motor function (3) used when automatically restarting the engine.
The ECM controls electricity generation based on information received from the electric load current sensor & battery temperature sensor, regardless of the activation status of deceleration energy regenerating function, in order to maintain optimum battery condition.
SHVS System Communication: ISG incorporating CAN driver communicates with ECM via CAN communication. ISG is monitoring sensors incorporated in ISG and, when detecting any abnormality, the information is transmitted to ECM and ECM performs a control to enter the fail-safe mode according to the level of the abnormality.
ISG Mechanical Operation: In the same manner as a conventional generator, the ISG (1) is connected with the crankshaft pulley (2) via the ISG drive belt (3). The ISG, instead of starting motor, enables the engine to restart and, through this, improved quietness when automatically restarting the engine is achieved. Drive belt auto tensioner (4) is adopted to stabilize the belt tension and restrict the slippage corresponding to large driving force when ISG is power assist mode.
ISG Operation:
1.
Engine power assist and starter motor functions
When ISG operates as starter motor or in the engine power assist mode, the power circuit transistors are turned ON, and direct current from the battery (lead-acid battery) or auxiliary power module (lithium-ion battery) is converted into three-phase (six-phase) alternating current passing through each transistor side of the power circuit. Three-phase (six-phase) alternating current passes through the three phase (six-phase) winding of the stator to generate torque in the rotor and causing rotation as a motor.
2.
Generating and deceleration energy regenerating functions: In the same manner as a conventional generator, passing current through the rotor field coil causes the rotor poles to be magnetized, and electromagnetic induction alters the magnetic field of the stator to generate electricity. The electricity generated in the stator is three-phase (six-phase) alternating current, and when it passes through the power circuit in ISG, it is rectified into direct current to charge the battery (lead-acid battery) and auxiliary power module(lithium-ion battery).
In this generating mode, the power circuit switches the transistors to ON during rectification, and the electricity generated by the stator passes through each transistor side to perform synchronous rectification.
Description of SHVS System Components: The SHVS system consists of the following components-
ECM: ECM transmits ISG control request signal via CAN corresponding to the condition of the vehicle.
ISG: ISG is fitted in the same position with conventional generator and mainly consists of a stator coil, rotor, rotor speed sensor and inverter (control circuit, field circuit, power circuit, CAN driver, temperature sensor and field current sensor). ISG has a generator function to generate electricity and a driving function to assist engine power or to start the engine. ISG monitors all internal sensors and when any malfunction is detected, ISG transmits the information to ECM via CAN and enters the fail-safe mode.
Battery (lead-acid battery): Supplies electricity to ISG when restarting engine controlled by ENG A-STOP system.
Auxiliary power module(lithium-ion battery): Supplies electricity to ISG while assisting engine power controlled by SHVS system.
CPP No.1 switch / CPP No.2 switch (M/T model): These switches are installed on clutch pedal bracket. The switches provide ECM with information on the state of the clutch pedal.
Neutral position switch (M/T model): This switch is installed on transaxle case. ECM determines whether the gear is in neutral based on the signal from this switch.
Transmission range sensor (A/T model): This sensor is installed on transaxle case. TCM detects select lever position (P, R, N,D, 2, L)
Combination meter
- When any malfunction is detected, ECM controls ENG A-STOP warning light to blink and charge warning light to turn on. The warning lights are turned off when ECM detects normal condition.
- Status of SHVS system i.e. each of engine auto restart, power assist and deceleration energy regeneration is indicated on the information display (energy flow indicator).
Brake stroke sensor: The sensor is fitted to brake pedal, and detects the depressing degree of the brake pedal. ECM uses this information to engine auto stop control and engine auto restart control.
Description of SHVS System Control Generating Mode: While the vehicle is decelerating, the generator generates electric power intensively to charge the lithium-ion battery
and lead-acid battery. This function is effective for improvement of fuel efficiency.
• ECM (1) transmits generation control signal, ISG torque request signal and supply voltage request signal to ISG (2).
• ISG controls generating torque and “B” terminal (3) voltage according to the request signals to charge the auxiliary power module (lithium-ion battery) (4) and battery (lead-acid battery) (5).
• While the generator is working in deceleration energy regenerating mode, ECM transmits energy flow indicator signal on combination meter (6) to indicate of deceleration energy regeneration.
Engine Restart Mode: Substituting ISG for conventional starting motor, ISG rotates crankshaft through ISG drive belt and pulley to auto
restart the engine without making gear noise of starting motor. With this auto restart mode, cranking speed is raised and the following effects are brought:
• Restricts engine speed to rise right after engine start.
• Stabilizes and converges engine speed right after engine start.
• Reduces fuel consumption accordingly.
• When the conditions to execute engine auto restart are satisfied, ECM (1) transmits ISG control request signal and
ISG torque request signal to ISG (2).
• ISG changes the power circuit to drive mode and the stator is energized to generate torque for restarting engine.
• Turning torque of ISG rotor turns crankshaft through ISG drive belt (4) and crankshaft pulley (3).
• ECM controls fuel injection to start engine.
• Electric power is supplied to ISG from the battery (lead-acid battery) (5) via auxiliary power module (lithium-ion battery) (6).
• While the generator is working in restart mode, ECM transmits energy flow indicator signal on combination meter(7) to indicate restarting.
Engine Power Assist Mode: When accelerating slowly, ISG (1) assists engine power to improve fuel efficiency.
• When conditions to assist engine power are satisfied, ECM (2) transmits ISG torque request signal to ISG.
• ISG changes the power circuit to drive mode and the stator is energized to generate torque for assisting engine power.
• Rotor turning torque of ISG assists turning of crankshaft through ISG drive belt (4) and crankshaft pulley (3).
NOTE
• Engine power assist by ISG continues for maximum 30 seconds.
• Power assisting torque varies according to the auxiliary power module (lithium-ion battery) (5)condition.
• ECM requests relay “3P” (6) to ON and electric power is supplied to ISG from auxiliary power module (lithium-ion battery).
• While the generator is working in power assist mode, ECM transmits energy flow indicator signal on combination meter (7) to indicate power assist.
Conditions which Auto Start stop checks before coming into picture:
Hope this eliminates many doubts.
Regards,
Shashi
PS: Credits: Maruti's Service Manual, service circulars and training documents