Stop/Start System
Achieving higher fuel efficiency by combining battery charge control and other systems
Lithium-ion Battery Pack
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Tandem Solenoid(TS) Starter
for Stop/Start Systems
Cold Storage Evaporator
Products for Stop/Start System
Tandem Solenoid (TS) Starter for Stop/Start Systems
Stop/Start systems help increase fuel efficiency by
automatically stopping the engine while the vehicle
is waiting at stop lights or is stopped for other
reasons to save fuel that would be wasted during
idling. The Tandem Solenoid (TS) Starter enables
the engine to restart more quickly and smoothly.
Conventional starters cannot restart the engine
while the engine is running down even after the
veh ic le has stopped . The TS Star te r , wh ich
features DENSO’s unique new mechanisms, can
restart the engine during engine coasting, thus
reducing the time needed before engine restart by
up to about 1 .5 seconds (a 80% dec rease
compared with DENSO’s conventional starters).
DENSO, which has been making starters since its
foundation, started full-scale mass production of
starters for Stop/Start systems in 1999. Based on
its technologies accumulated over many years,
DENSO will continue to improve product reliability
and make vehicles more environment-friendly.
Solenoid: Consists of a current-carrying coil of wire and a moving
iron core. The coil acts as an electromagnet when a current
passes through it and the iron core slides along the coil axis. In
starters, this component is used as an actuator to thrust the
pinion gear forward and a switch to supply power to the motor.
■Benefit
Stop/Start systems automatically stop the engine
when the vehicle is stopped, and also allow the
engine to coast for a while when the engine is
instructed to stop.
Conventional starters cannot restart the engine
until the engine has completely stopped, whereas
the TS Starter can restart the engine even while it
is coasting. Compared with DENSO’s conventional
starters, this advantage reduces the time needed
before engine restart by up to 1.5 seconds (a 80%
decrease in the time required to restart the engine
compared with DENSO’s conventional starters).
Re-start during engine run down
Re-start time during engine run down
Current : Wait then restart → Development : Immediately restart
waitingCurrent
Current
Time
(S)
Development
(TS Starter)
Restart demand
En
gi
ne
s
pe
ed
Waiting Time▲80%
Re-Start Time
Development
(TS Starter)
Current
1.5
1.0
0.5
0
Up to 1.5 seconds
En
gi
ne
r
es
ta
rt
t
im
e
(S
)
Tandem Solenoid (TS) Starter for Stop/Start Systems
■Feature The world’s first mechanism to separately control the forward slide of the pinion gear and the energization of the motor
Conventional starters thrust the pinion gear (the gear on
their front end) forward to engage the ring gear (the mating
gear on the engine) to transmit the rotation of the motor to
the engine via the pinion gear in order to start the engine.
Independent control of pinion gear shift and motor energization by two solenoids
Conjunctional control of pinion gear shift and motor energization by one solenoid
Tandem Solenoid Starter
EMS
EMS
Solenoid to shift pinion (SL1)
Pinion gear
Ring gear Engine Speed
Solenoid to energize motor (SL2)
Ring gear
Solenoid
EMS:Engine Management System
Current Product
●Conventional starter:Has a mechanism to shift the pinion
gear and to energize the motor conjunctionally.In this system,
the pinion gear cannot mesh with the ring gear until the engine
(ring gear) has stopped completely.
●TS Starter:Has the world’s first mechanism to separately
control the forward slide of the pinion gear and the energization
of the motor. In this system, sliding the pinion gear forward
according to engine speed and energizing the motor can be
controlled independently, thus allowing the pinion gear to
engage the ring gear while the engine (ring gear) is still rotating.
Tandem Solenoid (TS) Starter for Stop/Start Systems
■Engineering Key Point Separately control pinion gear forward movement and motor energization according to engine speed
(
rp
m
)
ⒶMotor on → ⒷPinion shift ⒷPinion shift → ⒶMotor on
Restart demand
Ⓐ Ⓑ
Restart demand
ⒶⒷ
(S) (S)
200
400
600
800
200
400
600
800
0 0.2 0.4 0.6 0.8 1.0 0 0.2 0.4 0.6 0.8 1.0
Starter
Engine
Timing of
engine restart
requests
Flow of control
※Engine restart requests: The driver’s actions identified as requests to restart the engine, such as releasing the brake pedal
Move the pinion gear forward and then energize the motor.
High engine (ring gear) speeds Low engine (ring gear) speeds
(
rp
m
)
Energize the motor to increase the rotational speed of the
pinion gear and then move the pinion gear forward when the
pinion gear and ring gear are rotating at almost the same rate.
Tandem Solenoid (TS) Starter for Stop/Start Systems
■Overview
●Lithium-ion battery cells can store more regenerative electric power.
●The small, lightweight, naturally air-cooled design increases the flexibility of installation.
Fuel efficiency can be improved by combining a stop/start system with a regenerative deceleration and
braking system which captures the kinetic energy of moving vehicle and converts it into usable electric
power instead of being dissipated as heat.To improve energy regeneration efficiency, DENSO has developed
a battery pack that can be used with a conventional lead-acid battery.
Lithium-ion Battery Pack
■Benefit
Lithium-ion Battery Pack
Work for electric generation
measured in NEDC test
Fuel efficiency improved by using DENSO’s lithium-ion battery pack: +3% (NEDC)
Vehicle speed
Adjusting voltage
Battery level
No battery charge
control performed
No fuel
consumed
Fuel efficiency
: +1%
Fuel efficiency : +3%
Deceleration and braking
Idling
Constant speed Acceleration
Fuel consumed
0 50 100 150 200 250(kJ)
Battery charge
control performed
Fuel efficiency can be improved by increasing the capacity to store
regenerative electric power produced during deceleration and braking.
Lead-acid
battery
Lithium-ion
battery
14.5V
Power generation increased
Power generation restricted
13.5V
12.5V
Idling
Acceleration Deceleration
and braking
Constant speed
Charge
Discharge
Battery level maintained
Battery charge control
Deceleration
and braking
Deceleration
and braking
Lithium-ion Battery Pack
Lithium-ion battery pack
Internal configuration
Voltage characteristics
Removed
DC-DC
converter
Alternator Starter Lead-acid
battery
Electric
load Protected loads
(navigation and
audio systems,
electric automatic-
transmission-fluid,
VSC solenoid, etc.)
・Lithium-ion battery cells selected to
match the lead-acid battery characteristics
・Improved regenerative efficiency by
enhanced input-output characteristics
V
ol
ta
ge
(
V
)
Lithium-ion battery
characteristics
Lead-acid battery
characteristics
Range of the Lithium-ion battery SOC
Lead-acid
battery
side
Protected
load side
Control
circuit
Lithium-ion
battery cell
MOS-FET
SOC(%)
■Engineering Key Point
Cold Storage Evaporator
Te
m
pe
ra
tu
re
o
f
a
ir
bl
ow
n
fr
om
th
e
ai
r
ou
tl
et
(
°C
)
Vehicle
traveling
Engine
restart
Conventional
Evaporator Cold Storage
Evaporator
Mode B Mode C Mode A Mode B Duration (sec.)
New product
(when used in a
vehicle with an ISS)
0
5
Previous product
(when used in a
vehicle with an ISS)
New product
(when used in a
vehicle without an ISS)
Fuel efficiency
changes depending
on the driving conditions.
Fuel efficiency improved thanks
to a longer duration before engine restart.Start
of
idle stop
Comfort: Doubling the time for which thermal
comfort is maintained
Fuel efficiency: Fuel efficiency
improved by approx. 2%
ISS:Idle Stop/Start
Approx.
twice as long
Engine
restart
■Overview
■Benefit
●Cold energy is stored in the cold insulator in the heat exchanger of the evaporator while the air conditioning
system is working, then cooled air is supplied while the engine is in the idle-stop mode.
●Thermal comfort is improved by limiting the rise in temperature of air supplied while the air conditioning system has stopped
working and improving fuel efficiency by lengthening the duration of idle stop (the amount of time before the engine is restarted).
Stop/Start is an effective way to improve fuel efficiency, but when the engine is at rest in this state, the air
conditioning stops working too. To supply cooled air to the vehicle cabin while the engine is not running, DENSO
has developed a new “Cold Storage Evaporator.”
Comfortable
temperatures
Fu
el
e
ffi
ci
en
cy
im
pr
ov
ed
by
id
le
s
to
p
(%
)
Approx. 2%
■Feature
Cold Storage Evaporator
Some parts of the fins used for the conventional evaporator are
replaced with a cold storage case filled with a cold insulator,
which is held by refrigerant tubes.
Outer fins are held between
refrigerant tubes.
Cold Storage Evaporator Conventional Evaporator
Inclusion pipe
Inner fins
Improve cold storage capacity
High-performance, non-corrosive
(two plates jointed together)
Cold insulator (paraffin)
Plate
Cold storage case Outer fins
Refrigerant tube
Outer fins
Refrigerant tube
Cold storage case
Cold Storage Evaporator
■Engineering Key Point
Vehicle traveling
(before the completion of cold storage)
Storing cold energy while the vehicle is running and discharging it while the vehicle is stopped
Mode A Mode B Mode C
Use refrigerant to cool the supplied air
and the cold insulator.
Vehicle traveling
(after the completion of cold storage)
Use refrigerant to cool the supplied air.
During Idle stop
Use the cold insulator
to cool the supplied air.
Air supplied
Refrigerant
Cold insulator
Air supplied
Refrigerant
Cold insulator
Air supplied
Cold insulator