附 录
附录A 外文文献原文
7-Speed Dual Clutch Transmission System for Sporty Application
ABSTRACT:With its 7-speed dual clutch transmission, ZF has introduced an innovative transmission for sporty applications. The clo ratios combined with extremely spontaneous drive behavior makes it an ideal transmission for sporty applications. This article describes the compact gear t with lubrication by injection for improving the level of efficiency and increasing the engine-speed-strength, the dual clutch unit as well as the hydraulic control unit, which is bad on the pre-control principle, are also described in detail. The hy-draulic control principle provides the option of a hydraulic crui mode in the event of an electronics failure. In addition to the transmission design, functional features that also highlight the sporty character of the transmission are described in detail.
Key words: Automatic transmission; Dual clutch; Vehicle connection; Efficiency
1 Introduction
When it comes to the field of automatic transmissions, dual clutch systems currently reprent the benchmark in terms of spontaneity and sportiness. In this type of transmission, which is bad on a countershaft transmission, the advantages are combined with a very direct "vehicle connection", high rpm performance, and excellent transmission efficiency.
The 7-speed dual clutch transmission for the standard driveline prented here is designed for a torque capacity of up to 520 Nm and rotational speeds of up to 9250 rpms. In order to be able to achieve the performance data in the existing installation space, a concept was developed in which an oil chamber as well as lubrication by injection are ud. Before introducing the transmission′s veral unique features in more detail below, an overview of the basic transmission design will be prented, Fig. 1.The engine torque is introduced to the dual clutch via a torsion damper (not shown in Fig. 1). The multidisk clutches in the dual clutch are radially nested in one another and transfer the torque to bo
th input shafts in the countershaft transmission gear t. In this ca, due to the installation space, the countershaft is not located under the main shaft, but is tilted laterally. This becomes possible becau the concept is bad on lubrication by injection with a dry sump. On the one hand, lubrication by injection improves heat removal, on the other, there are no noticeable loss due to the gears splashing in the oil pan. The oil is supplied to the transmission via an internal gear pump which is driven by a spur gear train behind the dual clutch. With the help of a spur gear train, the drive unit has the advantage that, via different gear ratio phas and depending on the intended u, the flow rate and the max. speed of the pump can be adapted. An additional advantage is that bad on theresulting I proved installation space, an optimal ratio between the pump width and the pump diameter can be achieved for the pump′s level of efficiency. The hydraulic control unit is arranged under the gear t. The hydraulic unit supplies the clutch, bad on need, with pressure and cooling oil as well as shift actuators. The latter are arranged laterally to the gear t and work with double-acting cylinders. The nsor for detecting the position of the gearshifts is attached directly onto the four gearshifts. The transmission has an external control unit.
Fig.1 Overview dual clutch transmission (DCT)
2 Seven speeds with sophisticated stepping-a concept for extrme sporti- ness
The gear t concept of the dual clutch transmission introduced here was developed in hou taking into consideration the following requirements:
High power density
High speed endurance strength up to 9250 rpm Variability and modular design
Reprentation of transmission-ratio spreads of about 4.7 and 6.8 with 7 speeds
U of existing synergies for manual transmissions
After extensive systematic development of the gear t in which many thousands of variants were produced and compared, the gear t concept that is illustrated in Fig. 2 is the final variant and the ideal concept for achieving the goals specified.
The gear t lected is bad on the constant drive concept and consists of two concentric drive shafts each of which are driven by one of the two multidisk clutches in the
Fig.2 Gear t scheme of 7D variant
dual clutch, two countershafts also concentric to one another, a main shaft and an output shaft. The gear ratios are engaged by the four synchronizer units A/B, C/D, E/F, and G/H, which are arranged on the main shaft and on the hollow countershaft and the are connected to the loo wheels or the adjacent shafts. An important feature in the gear t is the connectability of both countershafts through the C/D synchronizer unit. In the D shift position, the gear ratios lected in this way can be doubly ud which reduces construction costs compared to conventional dual clutch gear ts. Similarly, this feature is ud in first gear becau then the vehicle is started up using the more powerful K1 clutch. Becau of this dual u of the last gear level in the transmission for the first and cond gear, the desired ratio step 1-2 is achieved through the transmission ratios of both constant drive phas.
The u of the K1 clutch for starting up in first gear results inevitably in the direct gear also being assigned to the odd subction. In this ca, the fifth and venth gears can b
e lected as a direct drive. With this feature, it was possible to develop a modular gear t which, on just a few changes,contains two different transmission gear ratio variants with fundamentally different characters.
For the first version, with an overall spread of about 4 . 7 , the venth gear is lected as a direct gear (called the 7D variant). Fig. 2 shows the relevant gear t diagram with the performance flows in all speeds. Due to its sophisticated gear steps, this transmission is highly suitable for very sporty vehicles that need only a "little" transmission stepping due to the high rotating engine. Optimal tractive power can be provided at any time during vehicle operation.
