Browse Topic: Synchros
Model Based Design (MBD) uses mathematical modelling to create, test and refine systems in simulated environment, primarily applied in control system development. This paper discusses an approach to control gear shifting using shift logic on vehicle level for twin clutch transmission using prototype controller. Twin clutch transmission is a concept with two clutches, one at input end of the transmission called primary clutch and the other at output end of the transmission called secondary clutch. This concept is proposed to counter the challenges with conventional transmission which include increased gear shift time and effort in lower gears, potential rollback of vehicle in uphill condition and chance of missed shifts. The advantages of this concept include reduced gear shift effort and improved synchronizer life with potential for reducing the size of the synchro pack. This paper proposes a methodology to develop shift logic, integrate hardware with software, flashing and calibration on vehicle using prototype controller. The shift logic is implemented using state machines in ASCET. The state machine uses vehicle speed, accelerator pedal position, gear shifter input, shift maps and current gear to determine most optimal gear shift in real-time. This control logic is then converted into c-code and integrated with hardware using INTECRIO, which is a build environment where inputs and outputs are mapped accordingly for shift actuation. In the next step, .a2l and .cod files are generated, which are flashed onto rapid prototyping hardware from ETAS using INCA. The same is used to actuate shift solenoids of transmission to change the gear. Use of rapid prototyping hardware has significantly reduced the number of iterations required for integrating software with ECU from specific supplier, thus reducing overall development time. Final vehicle level calibration is done using INCA, followed by validation process to ensure optimal performance.
Gear shifting effort or force especially in manual transmission has been one of the key factors for subjective assessment in passenger vehicle segment. An optimum effort to shift into the gears creates a big difference in overall assessment of the vehicle. The gear shifting effort travels through the transmission shifting system that helps driver to shift between the different available gears as per the torque and speed demand. The shifting system is further divided into two sub-systems. 1. Peripheral system [Gear Shift Lever with knob and shift Cable Assembly] and Shift system inside the transmission [Shift Tower Assembly, Shift Forks, Hub and sleeve Assembly with keys, Gear Cones and Synchronizer Rings etc.] [1]. Both the systems have their own role in overall gear shifting effort. There has been work already done on evaluation of the transmission shifting system as whole for gear shifting effort with typical test bench layouts. Also, work has been on assessment of life of the synchronizer ring as standalone. Current paper explains the work done on the development of a methodology to evaluate the synchronizer ring assembly on a test bench that accommodates only a Synchronizer ring and Gear cone set for evaluation, and the results of which can be correlated with bench testing of the complete synchronizer ring evaluation along-with Transmission shifting system.
In today’s manual transmissions of car, gearshift system requires high performance with particular emphasis on low effort, minimal travel and positive feel. To meet these targets, a high capacity multi cone synchronizers along with higher co-efficient of friction material used for lower gears. The design of synchronizer with these specifications is influenced by torsional fluctuations from engine. Excessive torsional vibrations leads to wobbling of synchro rings within the peripheral clearances with surrounding parts. Wobbling leads to abrasion wear of frictional area of synchro ring causing grating or crashing noise of gears during shifting. This paper presents the optimization of the multiple cone synchronizer design exposed to excessive torsional vibrations and validation of the same on test bench during development stage instead vehicle level validation.
This specification covers the detail requirements for control transformer synchro, type 16CTB4b, 90 volt, 400 cycle.
This specification covers the detail requirements for control transformer synchro, type 19CTB4b, 90 volt, 400 cycle.
This specification covers the detail requirements for 115 volt, 60 and 400 Hz, size 23 synchros (see 6.1).
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