CAPÍTULO 2: DESCRIPCIÓN DE LA SOLUCIÓN
2.8 Implementación del Mercado de Datos
2.8.3 Estrategia Inicial de Indexado
7 Converter
7.1 Torque converter: Description
The torque converter is mounted on the input end of the planetary transmission. The torque converter consists of the impeller, turbine, and reaction mem-ber (stator) and the oil needed for torque transmis-sion.
Torque is transmitted from the engine flywheel to the torque converter by means of a connection comprising flex plates.
7.2 Converter functions
The impeller driven by the engine displaces the oil in a circular pattern. This oil flow strikes the turbine wheel and is deflected back.
The stator downstream of the turbine is used to deflect the oil flowing out of the turbine back into the impeller at an appropriate angle. This change in direction generates a torque on the stator, which in turn boosts the turbine torque. The ratio of turbine torque to impeller torque is referred to as torque conversion. The greater the difference in the speeds of the impeller and turbine, the higher the torque multiplication. In other words, maximum multiplica-tion occurs when the turbine is stamultiplica-tionary, and falls as the turbine speed rises.
The converter adjusts the output speed to achieve the required output torque using a continuous, auto-matic process. The torque of the stator is always equal to the difference between the turbine and impeller torque.
When the turbine speed approaches approx. 80% of the impeller speed, torque multiplication drops to a ratio of 1, i.e. turbine torque equals impeller torque.
From this point on, the converter acts purely as a fluid coupling. Under such conditions the stator, which is linked to the housing by a roller freewheel unit ("Trilok" principle) begins to rotate freely in the oil flow, whereas it is held against the housing by the
freewheel when torque multiplication takes place and thus remains stationary.
To ensure economical operation, the torque conver-ter lock-up clutch is closed as soon as this is possible.
When the lock-up clutch is closed, the level of slip between the impeller and turbine wheel and there-fore the loss of hydraulic energy in the converter is
"zero".
The close ratios and optimum gear step adjustment of the 5th and 6th mechanical gears in the trans-mission allow the converter to be locked up at a very early stage. This makes use of the advantages of mechanical power transmission early on high efficiency and low power losses.
Converter ZF-Ecomat 2 plus
7-2
4149 765 103 - 2004-12
4139 S 2015
Turbine wheel Impeller
From engine
Condition at instant of starting off
Stator
nT= O
Vehicle stationary
nT< nEng
nT= 0.8nEng nT= nEng
After lock-up clutch closes
TP = Torque of impeller TT = Torque of turbine wheel TR = Torque of stator
Intermediate condition
Condition immedia-tely before lock-up clutch closes
To transmission
TP TR TT
4166 703 150
4166 703 147
4166 703 149
4166 703 148
01 14500 16300 1000 221 970Z
01 26200 26200 1000 240 1000Z
01 30000 30050 1000 236 1000Z
01 34200 34200 1000 227 1000Z
01 39000 39000 1000 216 1000Z
01 39200 41800 1000 219 1000Z
01 48700 49000 1000 198 1000Z
01 61500 63900 1000 183 1000Z
145
4166 711 150
4166 703 227 01 41210 41210 1400 243 1000Z
4166 711 145
4166 711 147 4166 711 146 1.982
ZF-Ecomat 2 plus
7.3 Getting the right torque converter for your engine
In cooperation with vehicle manufacturers, the ZF Application Engineering dept. has specified an appropriate torque converter for every engine trans-mission combination.
The torque converter selection criteria are:
• Engine type (naturally-aspirated engine or turbo-charged engine).
• Torque conversion when starting off.
• Speed reduction when starting off.
• Fuel economy or power increase.
• Heat build-up when driving for long periods with lock-up clutch open.
Refer to torque converter diagram for details of appropriate engine-converter combinations, see example of torque converter diagram on page 7-5.
To determine the operating points between torque converter and engine under full-throttle conditions, the net engine torque curve needs to be entered in the primary parabolic characteristics field for the torque converter.
There are converter models for the 5/6 HP 502 / 592 / 602 C transmissions which vary according to the impeller torque pickup, hydraulic diameter, and torque multiplication when starting off.
W360*TPC262*MUE2.40
Converter ZF-Ecomat 2 plus
7-5
4149 765 103 - 2004-12
7.4 Torque converter diagram
The following information can be read from the torque converter graph (see drawing on next page):
• Stall torque = max. turbine torque TT= impeller torque TPx max. multiplication
µ
o(Mue) at turbi-ne speed = 0.• Stall speed = impeller speed nPat turbine speed nT= 0 rpm.
• Engine power Penggross (kW)
• Engine power Pengnet (kW)
• Torque curve Tenggross (Nm)
• Torque curve Tengnet (Nm)
• T2(Nm) subtraction for auxiliaries such as auxi-liary steering pump, generator etc.; approximate value of T2= 50 Nm may be assumed. If units with especially high power requirements are planned, e.g. a compressor, torque must be calculated according to impeller speed,
• TTturbine torque (Nm) against turbine speed
• PV(kW) torque converter power losses against turbine speed nT
Example:
nT= 800 rpm PV= 55 kW
• nPimpeller speed against turbine speed nT
Example:
• Torque converter efficiency rating ηW
The torque converter efficiency rating is deter-mined by the product of torque conversion m and speed ratio n.
ηW= µ • ν
The efficiency rating of 80% is achieved at ν = 0.8.
Calculation formulae
• Formula for calculating torque pick-up for any speed ratio.
n12 T1
--- =
---n22 T2
• Calculation of “HEAT REJECTION” for a given tractive force: Refer to example.
Example:
Heat build-up for tractive force = 60% vehicle weight Tractive force:
Using value of TT consult torque converter diagram TT--› curve TT--› PV--› axis P --› heat build-up P (kW) Example:
TT= 1200 Nm PV= 49 kW
TT= Turbine torque F = Tractive force iG = Transmission ratio iA = Rear axle ratio
ηG= Transmission efficiency approx. 0.95 ηA= Axle efficiency approx. 0.95
rdyn= Dynamic tire radius NOTE
When defining engine cooling constant, take account of additional heat build-up during torque converter operation (20% torque converter drag)!
Converter ZF-Ecomat 2 plus
Torque converter diagram
Key to diagram
TengGr[Nm] = Engine torque curve (gross) PengGr[kW] = Engine power curve (gross) nP[1/min] = Impeller speed against turbine
speed nT
TT[Nm] = Turbine torque against turbine speed nT
PV[kW] = Torque converter power losses against turbine speed nT
Mue [-] = Torque multiplication ration m = TT/TPagainst speed ratio Nue = nT/nP
TP[Nm] = Parabolae of impeller torque pick-up against impeller speed nPfor speed ratio Nue = nT/nP
A = Stall torque
B = Stall speed
Engine data = According to ISO 1585 (average values)
Converter = According to VDI Guideslines figures 2153 figures (average values)
014 914
Converter ZF-Ecomat 2 plus
7-7
4149 765 103 - 2004-12
7.5 Torque converter basic curves W360*TPC145*MUE2.22
Basic curve: 4166 711 150 Impeller constants: nPC= 1000 rpm
1000 2000 3000
µ η η = ν ∗ µ Torque converter efficiency TPC Pump torque at constant pump speed nPC
K = nPC
TPC
Factor at constant pump speed nPC
TP Pump torque at pump speed nP
TT Turbine torque at turbine speed nT
Torque converter values: acc. to VDI Guidelines 2153 mean values
Converter ZF-Ecomat 2 plus
W360*TPC210*MUE2.43
Basic curve: 4166 703 227
Impeller constants: nPC= 1400 rpm
0
0 0.2 0.4 0.6 0.8 1.0
1000 2000 nT, nP (1/min) 3000
200 η = ν ∗ µ Torque converter efficiency TPC Pump torque at constant pump speed nPC
K = nPC
TPC
Factor at constant pump speed nPC
TP Pump torque at pump speed nP
TT Turbine torque at turbine speed nT
Torque converter values: Acc. to VDI Guidelines 2153 mean values
Converter ZF-Ecomat 2 plus
7-9
4149 765 103 - 2004-12
W360*TPC262*MUE2.40
Basic curve: 4166 703 147 Impeller constants nPC= 1000 rpm
1000 2000 3000
µ η = ν ∗ µ Torque converter efficiency TPC Pump torque at constant pump speed nPC
K = nPC
TPC
Factor at constant pump speed nPC
TP Pump torque at pump speed nP
TT Turbine torque at turbine speed nT
Torque converter values: Acc. to VDI Guidelines 2153 mean values
Converter ZF-Ecomat 2 plus
W360*TPC300*MUE2.36
Basic curve: 4166 703 149
Impeller constants nPC= 1000 rpm
1000 2000 3000
µ η η = ν ∗ µ Torque converter efficiency TPC Pump torque at constant pump speed nPC
K = nPC
TPC
Factor at constant pump speed nPC
TP Pump torque at pump speed nP
TT Turbine torque at turbine speed nT
Torque converter values: Acc. to VDI Guidelines 2153 mean values
Converter ZF-Ecomat 2 plus
7-11
4149 765 103 - 2004-12
W360*TPC342*MUE2.27
Basic curve: 4166 703 148
Impeller constants nPC= 1000 rpm
1000 2000 3000
µ η η = ν ∗ µ Torque converter efficiency TPC Pump torque at constant pump speed nPC
K = nPC
TPC
Factor at constant pump speed nPC
TP Pump torque at pump speed nP
TT Turbine torque at turbine speed nT
Torque converter values: Acc. to VDI Guidelines 2153 mean values
Converter ZF-Ecomat 2 plus
W360*TPC390*MUE2.17
Basic curve: 4166 703 150
Impeller constants: nPC= 1000 rpm
1000 2000 3000
µ η = ν ∗ µ Torque converter efficiency TPC Pump torque at constant pump speed nPC
K = nPC
TPC
Factor at constant pump speed nPC
TP Pump torque at pump speed nP
TT Turbine torque at turbine speed nT
Torque converter values: Acc. to VDI Guidelines 2153 mean values
Converter ZF-Ecomat 2 plus
7-13
4149 765 103 - 2004-12
W390*TPC392*MUE2.20
Basic curve: 4166 711 145
Impeller constants nPC= 1000 rpm
1000 2000 3000
µ η η = ν ∗ µ Torque converter efficiency TPC Pump torque at constant pump speed nPC
K = nPC
TPC
Factor at constant pump speed nPC
TP Pump torque at pump speed nP
TT Turbine torque at turbine speed nT
Torque converter values: Acc. to VDI Guidelines 2153 mean values.
Converter ZF-Ecomat 2 plus
W390*TPC487*MUE1.98
Basic curve: 4166 711 146
Impeller constants: nPC= 1000 rpm
1000 2000 3000
µ η η = ν ∗ µ Torque converter efficiency TPC Pump torque at constant pump speed nPC
K = nPC
TPC
Factor at constant pump speed nPC
TP Pump torque at pump speed nP
TT Turbine torque at turbine speed nT
Torque converter values: Acc. to VDI Guidelines 2153 mean values.
Converter ZF-Ecomat 2 plus
7-15
4149 765 103 - 2004-12
W390*TPC615*MUE1.83
Basic curve: 4166 711 147
Impeller constants: nPC= 1000 rpm
1000 2000 3000
µ η = ν ∗ µ Torque converter efficiency TPC Pump torque at constant pump speed nPC
K = nPC
TPC
Factor at constant pump speed nPC
TP Pump torque at pump speed nP
TT Turbine torque at turbine speed nT
Torque converter values: Acc. to VDI Guidelines 2153 mean values.