142 TR A NSMISSI O N SYST EMS 8 1438 T R A NSMISSI O N SYST EMSSchaeffler Symposium 2018 tems Against the background of increasingly strict CO2 legislation however the indirect costs of consumption and power losses that lead to in creases in CO2 emissions due to drag losses and power consumption of actuators and cooling sys tems must also be reviewed 10 Figure 9 shows three designs by Schaeffler with varying direct system costs and indirect opera ting costs With regard to power loss the systems with engagement bearings offer an advantage center and right The actuation system consists of a clutch slave cylinder and is activated by a hy drostatic clutch actuator HCA It uses a leak free hydrostatic section to transmit the actuation en ergy to the clutch with little loss Due to a travel sensor the HCA does not need any additional re turn force gradient in relation to the engagement travel This allows the power losses in the clutch to be minimized A more cost driven approach is characterized by the use of a mechanically driven hydraulic pump left and if necessary supported by an addi tional electric pump to cover volume flow peak demands The transmission of clutch actuation energy is not achieved with the help of bearings but rather with rotary oil feeds and the actuation of the transmission shift system is achieved hy draulically or electro mechanically The system does have its disadvantages because of the con tinuously running pump but does well overall in terms of system costs Manual transmission In spite of an increasing variety of transmission concepts the manual transmission continues to be one of the most important transmission de signs with regard to volumes This means that ef ficiency gains have a particularly strong effect globally In order to utilize any additional poten tial offered by new technologies to reduce fuel consumption and CO2 emissions however it is advantageous to automate the clutch in manual transmissions Based on measurements by Schaeffler using a sailing only strategy on an RDE compliant test track allows fuel and CO2 sa vings of between 3 and 5 In addition the expanded recuperation of brake energy enables improvements of around 5 with P0 mild hybrids and when used in combination of around 8 11 Figure 10 shows three variants of how clutches of manual transmissions can be automated MTplus left is an entry level system for the par tial automation of the clutch that allows driving strategies such as sailing without the driver s involvement even for manual transmissions An additional actuator with a suitably small design is used in parallel with the existing master cylin der on the clutch pedal Clutch by wire systems CbW are also perceived as normal manual transmissions with a clutch pedal by the driver The actual actuation of the clutch however is always carried out by an actuator This allows additional functions such as the start assist traffic jam assist and slip control As the name by wire suggests there is neither a mechanical nor a hydraulic connection between the clutch pedal and the slave cylinder of the clutch This also applies for ECM systems right that do with out the clutch pedal altogether Instead a sen sor on the gear selector recognizes the intent to shift gears and controls the opening of the clutch via the actuator Besides its efficiency potential and new functions the automated clutch has the added benefit of being able to protect the manu al transmission from excessive loads for in stance in cases of misuse Summary With the growing number of drive concepts the variety of transmission designs and components also continues to increase This paper has shown 8 Design of the four channel torque converter with four hydraulic connections for compensating centrifugal oil pressure Apply port Cooling inlet Cooling outletCompensation port Rotating pistons and oil feeds wet Engagement bearings wet Engagement bearings dry 9 Wet double clutch with rotary oil feeds and rotating cylinders left as well as wet and dry double clutch with engagement bearings center and right nels are used for the flow through the converter The third channel serves to control the clutch and the additional fourth channel serves as a pres sure compensation chamber This fourth channel ensures identical fluid conditions on both sides of the piston The dynamic centrifugal force oil pres sure is identical on both sides of the piston be cause the diameters of the actuation and com pensation chamber seals are identical and the oil rotates at engine speed on both sides inde pendently of the slip speed In addition the pres sure chambers of the clutch are shielded from variations in converter charging pressure Double clutch transmission In transmission development so far the focus has been on the direct costs of components and sys

Vorschau Schaeffler Symposium 2018 Seite 142
Hinweis: Dies ist eine maschinenlesbare No-Flash Ansicht.
Klicken Sie hier um zur Online-Version zu gelangen.