COVER STORY TRANSMISSIONS AUTOMATED FIVE-SPEED MANUAL TRANSMISSION – EASYTRONIC 3.0 The new Opel/Vauxhall five-speed automated manual transmission or manual transmission automated (MTA) as the company calls it, introduced in the fall of 2014 as Easytronic 3.0, uses an electro-hydraulic clutch and shift control. Major components from the base manual gearbox (F17-5) are used as common parts. The new transmis- sion is stop/start capable, and its controls are based on a safety concept according to the ISO 26262 guidelines. AUTHOR DIPL.-ING. THOMAS ZEMMRICH is Group Leader and Technical Spe- cialist for Automated MT Systems in the Transmission Area of Adam Opel AG in Rüsselsheim (Germany). 34 www.autotechreview.com CONTINUED STRATEGY In the fall of 2014, Opel/Vauxhall intro- duced a new generation of its automated manual transmission MTA (Manual Transmission Automated), designated Easytronic 3.0. This continues a com- pany strategy started in 2001 to offer this type of gearbox as a low-cost, efficient alternative to a conventional automatic transmission for small and compact vehi- cles [1]. Even though these automated transmissions cannot reach the comfort levels of powershift transmissions – due to their inherent torque interruption dur- ing shifting – they offer a considerably easier operation than manual gearboxes because of their automatic actuation sequences, while also enabling lower fuel consumption [2] through correspond- ing functions and calibrations, as well as a sporty driving style. This article describes the design and performance 1 MTA transmission characteristics of Opel’s new MTA. be realised through fast automatic down- systems, the actuation of this newest gen- TRANSMISSION DESIGN shifts. A requirement for the new MTA eration is distinguished by higher integra- was that the same clutch can be used in tion. All components are mounted on a The latest development of Opel’s proven both manual and automated applications, baseplate, which incorporates the hydrau- five-speed manual transmission (F17-5), and that no MTA-specific adaptations are lic ducts so there are no external hydrau- with a torque capacity of 190 Nm, was necessary for vehicle integration. 2 lic lines. All internal sensors (shift/select chosen as the base. This transmission shows the transmission’s basic data. position and pressure) are also contacted enables the use of the new Opel MTA, 1, In contrast to the previous electro- without wiring. These features deliver in combination with small and mid-size mechanical system [1], an electro-hydraulic benefits in terms of cost, mass, package gasoline engines, currently up to 1.4 l actuator takes over the clutch and gear- and system reliability. with MTA, and the diesel engine with a shift operation in the new MTA. Its main To measure the input shaft speed, the 1.3 l displacement. While six-speed man- components include an electric motor, new MTA is equipped with a speed sen- ual transmissions with a torque capacity pump, pressure accumulator, oil reservoir, sor, using the Hall effect principle. The of up to 200 Nm are increasingly popular, block with solenoid valves and the control fourth gear wheel serves as the target. A the five-speed version remains the pre- module directly contacted to the valves separate target wheel is therefore unnec- ferred entry-level option in the small car (mechatronic), 3. essary, so all shafts from the manual segment for cost reasons. Compared to earlier electro-hydraulic transmission can be used unchanged in The shift forks and synchronisers of the base transmission are used without modifications for the automated variant. The selected gear set is characterised by a Characteristic Value comparably wide ratio spread for a five- Maximum torque 190 Nm speed gearbox of 5.53. Together with a Gear ratios 1st gear: 3.727 2nd gear: 2.136 correspondingly chosen final-drive ratio, 3rd gear: 1.323 this enables a high total ratio in first gear 4th gear: 0.892 for comfortable drive-off performance 5th gear: 0.674 Reverse gear: 3.308 with low energy influx in the clutch, as Final drives 4.188, 4.625 application dependent well as a lower engine rpm at higher driv- Centre distance 180 mm ing speeds in fifth gear for reduced noise Length 365 mm level and fuel consumption. Mass (dry) 39 kg, thereof electro-hydraulic actuator: 8 kg The latter is achieved for the auto- Transmission oil quantity 1.6 l mated manual transmission without any loss of performance, as acceleration can 2 Basic data of the MTA transmission autotechreview September 2015 Volume 4 | Issue 9 35 COVER STORY TRANSMISSIONS Another objective of the new MTA was optimisation of creep, i.e. drive-off only by controlling the clutch without depressing the accelerator pedal. Re-tun- ing of entry and exit into or out of the creep function is particularly beneficial when parking. Furthermore, creeping on slight uphill and downhill gradients is now also more comfortable. This latter improvement was achieved by the adop- tion of calibratible target accelerations, in relation to the gradients estimated by an MTA algorithm. 3 MTA actuator The newly introduced sprint-start func- tion enables drive-off with the highest possible acceleration when the accelerator the automated application. for traction force calls for a downshift to pedal is quickly depressed to the kick- As in the manual transmission, the first gear. The further developed upshift down position. Measurements show an clutch operation in the new MTA uses a prevention function guarantees selection increase in maximum acceleration of 1.9 hydraulic concentric slave cylinder (CSC), of the appropriate gear for required m/s², delivering a reduced time to 20 but without the need for a master cylin- minimum acceleration also in case of km/h of 0.3 s compared to a normal wide der. Instead of brake fluid, commonly increased driving resistance, e.g. during open throttle drive-off. used as a medium with manual gear- uphill driving or trailering or with Like other transmission types in Opel’s boxes, the MTA’s CSC is operated with the reduced engine torque due to altitude or powertrain portfolio, the new MTA is also actuating system’s hydraulic oil. A propor- heat. Together with optimised shift maps, stop/start capable. As with automatic tional valve takes over regulation of the these special functions lead to a transmissions, pressing or releasing the oil flow. The MTA CSC is also equipped considerable reduction in shift frequency. brake pedal during standstill is the pri- with a contactless travel sensor (Hall In an Opel test cycle, the number of gear mary trigger for engine stops and starts. A effect), which gives the controller the shifts is reduced from 231 with the special challenge to automated transmis- feedback required for closed-loop control existing Opel five-speed MTA to 195 sions is ensuring a delay-free and com- of the clutch release travel. The target is a shifts with the new version. This fortable transition from releasing the magnet connected to the base of the contributes to enhanced driving comfort brake pedal through starting the engine to clutch release bearing. The advantage of and lower fuel consumption. providing acceleration. Here, the MTA has position measurement on the CSC is that dynamic and temperature-caused effects in the hydraulic line are included in the control loop, as opposed to measuring the 6000 position on a master cylinder. On the other hand, the CSC’s axial pulsation with engine running is also detected by the 4500 sensor and super-imposed over the travel signal. Suitable filtering compensates for Speed [rpm] this effect during processing of the raw 3000 signal in the transmission controller. 01Time [s] 100 FUNCTIONS 50 The new MTA offers selectable automatic or manual operating modes, and also sup- ports the sport mode function as well as 0 Relative torque [%] cruise control. In automatic mode, numer- ous shift maps with further functions are 0 Torque Synchroni- 1 Time [s] available [2]. reduction sation A new feature is the conditional suppression of the 2-1 downshift at low Clutch data Engine data Driver requested speeds. It operates the clutch in slip in torque second gear as long as no higher demand 4 Upshift schematic 36 www.autotechreview.com COVER STORY TRANSMISSIONS Transmission Response time [ms] Ratio step related to shift time [1/s] this standard, a safety concept for the New MTA 125 5.1 new MTA was developed and integrated Predecessor MTA 150 4.2 in its controls [4]. This concept comprises Competitor MTA 134 4.4 specific requirements to the reliability of the components involved and diagnoses 5 Comparison of downshift characteristics on a number of levels, as well as situa- tional system reactions in the case of a failure to ensure a safe state. Such meas- to measure up to the demands made of For downshifts, the system’s respon- ures range from the deactivation of indi- automatic and dual-clutch transmissions, siveness is decisive. Here the new MTA vidual functions to interruption of the and could sometimes even surpass their benefits from an expanded interface to the power flow. The overriding objective is to performance in comparison tests. The engine controller, which enables precise guarantee safety during vehicle operation, decisive element is the shift strategy for speed control. 5 shows a comparison of while maintaining as much system availa- the stop phase. Holding first gear with an important downshift characteristics for bility as possible. open clutch, together with various safety different automated transmissions. measures, enables the system’s fast reac- The success of the various measures is REFERENCES tion at the start, while at the same time evident in improved driveability of [1] Barnbeck, A.; Becker, G.; Kiefer, M.; Quarg, J.; Zemmrich, T.; Fischer, R.: Automated shift of a preventing an undesired drive-off.