Continuously variable transmission( CVT) · Primary and secondary Vpulleys · Steel belt or chain · The gear-ratio change is continuously variable.
Automated manual transmission (AMT) · Diaphragmspring dry clutch · Spur gears · The gearratio change is stepped.
Chapter 6 Power train
3.5 Automatic gearbox
servos. When fluid passes through the accumulator on the way to the servo, it must move the accumulator piston against spri l systems (Fig. 3-14) are used on automatic transmissions or transaxles to control the line pressure, converter lockup, shift po
3.5 Automatic gearbox
Fig.3-12 band brake
Fig.3-13 A hydraulic system Chapter 6 Power train
3.5 Automatic gearbox
Chapter 6 Power train
3.5 Automatic gearbox
Chapter 6 Power train
3.5 Automtomatic transmission with hydrodynamic converter (AT)-Conventional automatic transmission Torque converter ( Fig.3-10 ) serves as a starting clutch to facilitates smooth and comfortable drawing away, transmits and multiplies the engine torque, and damps engine torsional vibrations. gear systems are used to multiply torques, reduce speeds and reverses the direction of rotation for the reverse gear. Most automatics use the planetary gear sets (Fig.3-11). The commonly used planetary gears are Ravigneaux set and Simpson set. A simple planetary-gear set can also be connected to the upstream or downstream of a Ravigneaux set or Simpson set. Either the outer gear or the sun gear may be held stationary, providing more than one possible torque multiplication factor for each set of gears. Also, if all three gears are forced to rotate at the same speed, the gear set forms, in effect, a solid shaft.
3.5.2 Continuously variable transmission The gear ratios of the gearbox are varied continuously over the entire working range by the primary and secondary V-pulley pairs. The primary V-pulley is driven by the planetary gear when the forward or reverse gear clutch is engaged. It drives the secondary V-pulley via a steel belt or a chain. Variation of the gear ratio is achieved by axial displacement of a diagonally opposite pulley half in each case. In this way, the effective pulley radius (rwl and rw2) are continuously varied in opposition, i.e. bigger or smaller (Figure.3-15). Displacement of the pulley halves is effected by the two pressure-controlled primary and secondary cylinders. The main components and operation of a CVT are shown in Figure 3-16 and 3-17.
Chapter 3 Power Train
本章讲授内容
Power Train 3.1 Clutches 3.2 Manual Transmission 3.3 Propeller Shafts and Universal Joints 3.4 Final Drive, Differential and Axle Shaft 3.5 Automatic gearboxes
paddle
['pæ dl]
n.桨，桨状物
Chapter 6 Power train
3.5 Automatic gearbox
Different types of automatic gearboxes are used: semiautomatic and fully automatic. Semiautomatic gearboxes. The power flow is interrupted by automatic clutch disengagement and cut in by clutch engagement, e.g. automatic clutch system (ACS). Shifting of gears to change the gear ratios and direction of rotation is performed manually by operating a shift lever. Fully automatic gearboxes. The power flow is automatically interrupted or cut in as required. Shifting of gears to change the gear ratios is performed automatically by electro-hydraulic or electropneumatic control. Automated manual transmission, Converter transmission and CVT are fully automatic gearboxes. The features of the gearboxes are listed in the Table 3-1.
Table 3-1 features of the fully automatic gearboxes
Conventional automatic transmission (AT) · Hydrodynami c torque converter · Planetary gear set · The gearratio change is stepped.
Chapter 6 Power train
3.5 Automatic gearbox
Fig.3-10 Torque converter
Chapter 6 Power train
3.5 Automatic gearbox
Fig.3-11 planetary-gear set
Chapter 6 Power train
3.5.1 Stepped automatic transmission with hydrodynamic converter (AT)-Conventional automatic transmission Torque converter ( Fig.3-10 ) serves as a starting clutch to facilitates smooth and comfortable drawing away, transmits and multiplies the engine torque, and damps engine torsional vibrations. gear systems are used to multiply torques, reduce speeds and reverses the direction of rotation for the reverse gear. Most automatics use the planetary gear sets (Fig.3-11). The commonly used planetary gears are Ravigneaux set and Simpson set. A simple planetary-gear set can also be connected to the upstream or downstream of a Ravigneaux set or Simpson set. Either the outer gear or the sun gear may be held stationary, providing more than one possible torque multiplication factor for each set of gears. Also, if all three gears are forced to rotate at the same speed, the gear set forms, in effect, a solid shaft.