More choices then you think.
The ZF 4HP20 Sportmatic gearbox is totally automatic with electro-hydraulic operation and 4 forward speeds plus reverse.
An electronic control unit manages:
the torque converter
the gear changes
the specific programmes.
The Sportmatic solution allows the driver to also use the vehicle in sequential, manual conditions as well as completely assisted in the auto-adjustment operation mode.
The gearbox is equipped with a hydro-dynamic torque converter with an anti-slip device which allows demultiplication ratios.
The 2.6 V6 and 3.0 V6 versions differ through the gearbox ratios and through the different electronic control unit management software.
A feature of this gearbox is that it perates without a free wheel because the gear change takes place by overlapping the couplings which allows:
improved compactness and more lightweight
improved efficiency due to the reduction in friction
lower torque points for the components and kinematic chain.
1, Gear selector lever
2, Electronic control unit
3, Gear control cable
4, Hydraulic circuit cooling radiator
5, Gear position indicator
6, System failure/oil temperature warning light
7, Automatic transmission
The electronic management of the gearbox makes it possible to produce flexible gear shifts as appropriate.
The control unit has the task of:
adjusting the oil pressure to the engine torque for gear changes
implementing the safety functions
defining the gear change programme
carrying out the system fault diagnosis.
The control unit uses the following signals for the management of these logics:
engine rpm (through the injection control unit)
butterfly position (through the injection control unit)
engine temperture (through the injection control unit)
converter turbine speed
gearbox output rpm
vehicle speed (A.B.S.)
gearbox oil temperature
gear selector lever position
accelerator pedal position (kick-down, through the injection control unit)
brake pedal position (A.B.S.)
In addition, the control unit converses, through the CAN line (Controller Area Network), with the A.B.S. control unit and the injection/ignition control unit.
1, Input shaft rpm sensor
2, Output shaft rpm sensor
3, Driver's door switch
4, Gearbox oil temperature sensor
5, A.B.S. control unit / CAN line
6, Injection-ignition control unit / CAN line
7, Water/oil cooling fan
8, Instrument panel
9, Gear lever position LED cowling
11, Solenoid valves MV1 and MV2
12, Release for lever in "P"
13, Pressure regulators (REG1 - REG2 - REG3 - REG4)
14, Key lock
15, Diagnostic socket
16, Switch on gear lever for recognizing auomatic/manual management
17, Selector lever position sensor (P - R - N - D)
18, Starting go ahead
19, Reversing lights
Ags adapation management
Thanks to the signals received from the injection control unit and the ABS control unit (through the CAN line), the automatic transmission control unit is capable of making an autonomous selection of the:
optimum gear change programme (shift programme)
Usage conditions analyzed by the control unit
The control unit analyzes each individual vehicle usage condition, distinguishing it on the basis of the signals received from the various sensors.
The following conditions are analyzed:
starting (accelerator pedal/potentiometer position/speed variation)
acceleration (accelerator pedal/potentiometer depression speed)
full load (number of engine kid-down full load signals or position maintenance time)
braking (release speed of accelerator pedal and intervention of braking system)
type of programme (gear selector lever position)
winter driving (slipping of drive wheels/ABS active sensors)
driving with a trailer or uphill (vehicle speed dependent on the torque transmitted)
entering a bend (transverse acceleration detected by the difference in rotation of the wheels on the two sides/ABS active sensors)
driving downhill (vehicle acceleration dependent on the accelerator pedal/potentiometer position)
driving in town or in traffic (acceleration pedal/potentiometer position and vehicle speed)
gear requested by the driver (gear selector lever position)
cold starting (engine temperature).
Gear change management programme (shifting programme)
The control unit contains programmes in its memory for optimizing the gear the vehicle is in:
high oil gearbox temperature safety (SKT)
Automatic programme (dsp)
The automatic driving mode consists of 12 gear change programmes divided into 3 main groups:
low sports (S1)
medium sports (S2)
high sports (S3).
The remaining 4 divisions in these groups are:
downhill road (B0)
flat road (B1)
uphill road (B2)
steep uphill road (B3)
The gearbox control unit, according to the:
recognizes the inclination of the road surface (B0) and, on the basis of the sports drive setting (S), autonomously selects the most suitable programme for the situation.
B, Road gradient
S, Sports level
( ), Condition considered by the software, but in reality not achieved
On the basis of the engine type, there are different road gradient thresholds for selecting the various programmes automatically.
"High sports" downhill
"Medium sports" downhill
"Low sports" downhill
"High sports" flat road
"Medium sports" flat road
"Low sports" flat road
"High sports" uphill
"Medium sports" uphill
"Low sports" uphill
"High sports" steep uphill
"Medium sports" steep uphill
"Low sports" steep uphill
For each main group there are a further 15 additional operating curves for adjustment to the operating situation:
3 up-shift programmes for changing to a higher gear
3 down-shift programmes for changing to a lower gear
9 lock-up management programmes (2 - 3 - 4)
Lastly, each lock-up programme possesses a further eight data points and an additional kick-down point.
When operating automatically and with the lever in the Drive position, the programme allows a double down-shift simply by fully depressing the accelerator pedal in 0.1 seconds.
Whilst changing gear, the CAE control unit requires a momentary reduction in torque from the injection control unit. The duration of this request is calculated by the CAE control unit starting from the turbine rotation speed (input shaft inductive rpm sensor).
Automatic sports operation
In these circumstances, the electronics favour a sports gear change management. With this in mind, the software uses programmes which reflect this logic.
The choice is restricted to the following programmes.
S2 B2 uphill road
S2 B3 steep uphill road
S3 B2 uphill road
S3 B3 steep uphill road
These programmes are also used in automatic management (Drive) with different selection thresholds where it would be very difficult for the electronics to select sports programmes.
In automatic sports operation these selection thresholds are less "strict".
Manual operation (tip)
The Tip function allows the manual use of the gearbox.
by moving the gear selector lever:
forwards (+) the change is to a higher gear (up)
backwards (-) the change is to a lower gear (down).
There is only one change for each request: it is not possible to accumulate the request.
The control unit inhibits gear change requests if the gearbox output shaft speed (output shaft inductive rpm sensor) is not between certain limits to avoid the engine speed being too high or too low.
Winter programme (wnt)
This programme is engaged automatically depending on the slipping of the drive wheels (ABS active sensors) and requires a learning time of around 0.3 seconds.
On the basis of specific curves, it makes provision for gear shifts 2, 3, 4 and viceversa.
This programme does not allow starting in 1st speed.
Warm up programme (wml)
This is a programme derived from a special configuration of the "SKT" programme which helps the engine reach operating temperature quickly raising the gear change points (sports logic) according to the temperature of the engine.
It is activated, after starting, if the temperature of the engine coolant is below 30°
High gearbox oil temperature safety programme (skt)
This programme is activted when the temperature of the gearbox oil reaches 120°
Up shift and down shift gear change inhibition functions have been introduced into this programme.
It is, however, position to engage and use the TIP manual programme.
The CAE control unit implements for the following strategies to facilitate the cooling of the gearbox oil:
it activates the lock-up clutch to reduce the Jaule effect in the converter
it sends oil temperature information, via the CAN line, to the injection control unit for the management of the cooling fan (not used by the injection control unit).
Inhibition of gear changes round bends
The control unit inhibits a change to a higher gear if there is strong transverse acceleration (bend) with the accelerator pedal released very rapidly. The system maintains the last ratio selected.
The system automatically restores the automatic programme when the critical period is over.
This strategy affords:
better vehicle equilibrium
prompt acceleration coming out of the bend because the vehicle finds itself in the ideal gear.
Change to a lower gear (down shift) whilst braking
In the case or emergency or rapid braking, the control unit selects the lowest permissible gear to achieve the maximum engine braking effect.
This depends on the:
type of braking
gradient of the road
type of driving (sports level).
The tables below illustrate gear changes 4-3 and 3-2 (down shifts) on the basis of the vehicle speed.
A, Repeated braking
B, Gentle braking
C, Medium braking
D, Strong braking
E, Emergency braking
A system locks the gear selector lever when it is in position P until the brake pedal and the button on the gear lever grip are pressed with the ignition in the ON position.
If the case of a failure, there is a manual release safety device, located at the side of the centre tunnel (passenger side). A rubber plug must be removed to gain access to this device.
The key can only be removed from the ignition with the gear selector lever in position P for a maximum of 25 seconds after the key off.
If there is a failure, there is a manual release safety device, located under the ignition lock barrel.
A special buzzer, located in the LED cowling on the gear lever, warms the driver for a maximum of 15 seconds whilst the driver's door is opened that the gear selector lever is not in position P.
Outside of revs
This function is designed to prevent damage to the engine through too high a rotation speed.
The CAE control unit sets a higher gear before an excessive speed is reached or prevents (delays) the shift to a lower gear to avoid a similar risk condition.
The engine can only be started up with the selector lever in position "N" or "P".
With the selector lever in position "R", reverse gear will not be engaged if the vehicle speed is above a pre-set level.
When the speed goes below the threshold, reverse gear is engaged and remains engaged even if the speed goes above the threshold again.
The reversing lights come on with the selector lever in position "R".
Gearbox failure warning light
A single warning light in the instrument panel signals:
gearbox oil overheating with the warning light on constantly (on with the oil temperature >140° C and off with the oil temperature <137° C)
- automatic transmission failure with the warning light flashing (on for 4 seconds and then flashing).
- system working properly (on for 4 seconds and then off).