Model Based Control of Synchronizers for Reducing Impacts during Sleeve to Gear Engagement

This paper presents a model based control strategy aimed to reduce noise and wear during gearshifts in conventional and hybrid Dual Clutch Transmissions (DCT and DCTH) and Automated Manual Transmissions (AMT). The control strategy is based on a newly developed dog teeth position sensor layout at China Euro Vehicle Technology AB (CEVT), a detailed simulation model for gear engagement and already existing speed sensors in the transmission. The details of dog teeth position sensor and simulation model are also presented in this paper. During gear shifting, noise is generated because of impacts between the sleeve teeth and the idler gear dog teeth after speed synchronization. Besides noise, these impacts are also responsible for delaying the completion of shift and contribute to wear in the dog teeth, hence reducing the lifespan of the transmission. The simulation model for gear engagement can simulate these impacts. Based on the simulation model and optimal control theory, an ideal dog teeth position trajectory is formulated that avoids the impact between sleeve and idler gear dog teeth, before the start of torque ramp up. The open loop strategy then controls the synchronization torque in the beginning of speed synchronization in such a way that the dog teeth position during shift follows the ideal dog teeth position trajectory. Since the control strategy is based on optimal control theory, its effect on speed synchronization time is minimal. The control strategy is designed in such a way that it can easily be applied in the existing transmission control software. By applying the control strategy on the simulation model, it is shown that the impacts during gear engagement are reduced

Improved efficiency with adaptive front and rear axle independently driven powertrain and disconnect functionality

Front and rear axle independently driven (FRID) powertrains are becoming a popular solution for electric vehicles (EVs) due to torque distribution capability which can enhance powertrain energy efficiency. Typically, permanent magnet synchronous machines (PMSMs) are used for FRID powertrains due to their high torque, and power density. However, the drive-cycle efficiency of FRID powertrains with PMSMs is typically reduced in comparison to single motor drives. This is due to the unwanted no-load losses of PMSMs in the field weakening region. To overcome this drawback of PMSM FRIDs, this paper proposes an adaptive front- and rear-axle independently driven (AFRID) powertrain, utilizing two dog clutches, so that the powertrain can be operated in different modes (rear, front, and all-wheel drive) by adaptively connecting and disconnecting the front and/or rear electric drive unit (EDU). A rule-based mode selection strategy is developed to utilize the flexibility of different powertrain operating modes of the powertrain for maximizing the energy efficiency of the EDU. The simulation results show that the suggested AFRID powertrain, in comparison to a common FRID powertrain, can improve the WLTC drive-cycle consumption from 22.17 kWhh to 20.50 kWhh per 100 km. Based on the route and road-load information, the energy-saving potential of the AFRID powertrain can be further improved to 20.37 kWhh per 100 km by a suggested predictive mode selection strategy, achieving an optimal mode selection

Varför går inte studenter till tandläkaren?

Syfte. Att undersöka kunskaperna om allmänt tandvårdsbidrag (ATB) hos 20-29 åriga studenter vid Malmö högskola. Beskriva deras regelbundna besöksfrekvens inom tandvården och vilka anledningarna var till att vissa besökte tandvården regelbundet och andra inte. Vad som hade kunnat öka studenternas besöksfrekvenser och undersöka besöksfrekvens hos de med abonnemangstandvård. Material & metod. En enkät med 17 frågor utformades. Urvalet skedde genom ett stratifierat bekvämlighetsurval vid Orkanenbiblioteket. Etthundrafemtioåtta studenter tillfrågades varav 108 valde att delta i studien. Resultat. Fyrtiofyra procent (n=47) kände till att ATB fanns och av dem kände 34 % (n=16) till det exakta beloppet. Sjuttiotre procent (n=79) av studenterna gick regelbundet till tandvården. Fler av dem som inte gick regelbundet kände till ATB än dem som gick regelbundet. Största anledningen till regelbundna besök var att man uppskattade att få sina tänder kontrollerade. Största anledningen till oregelbundna besök var att studenterna inte hade råd. Kallelser och kostnadsfria undersökningar uppgavs kunna motivera studenter att öka sin besöksfrekvens inom tandvården. Nittioåtta procent av dem som hade abonnemangstandvård gick regelbundet. Slutsats. Kunskapen om att ATB fanns innebar inte en högre besöksfrekvens inom tandvården jämfört med de som inte kände till ATB. Studenternas kunskaper om ATB var låga och tydde på stora brister i informationen som skulle ha nått 20-29 åriga individer. Det visade sig att om man erbjöd abonnemangstandvård eller följde upp studenter med kallelser kunde den regelbundna besöksfrekvensen ökas.Aim. To investigate 20-29 year old students’ knowledge of Sweden’s general dental subsidy (ATB) at Malmö University. To describe students’ frequency of having regular dental checkups and reasons for why students went regularly to checkups and some did not. To describe what motivated students to increase their checkup frequencies and the effect of subscription on dental care. Method. A questionnaire with 17 questions was formulated. The selection proceeded by a stratified convenience sample. One hundred and fifty-eight students were asked to participate whereof 108 chose to participate. Results. Forty-four percent (n=47) had knowledge of ATB, of which 34% (n=16) knew its precise amount. Seventy-three percent (n=79) of students went to regular checkups. Those who did not attend regular checkups and had knowledge of ATB were more than those who attended regularly. Main reason for regular checkups was appreciation of having teeth controlled. Main reason for irregular checkups was not being able to afford them. Invitations and free checkups were stated as motivating reasons for students to increase their dental visit frequency. 98% of those who had subscription on dental care went to regular checkups. Conclusion. The knowledge of ATB existence did not result in a higher dental checkup frequency in comparison to those who did not know of its existence. Student’s knowledge of ATB was low which indicated major flaws in information supposed to reach individuals aged 20-29 years. It was shown that by offering subscription on dental care or checkup invitations, the frequency of regular checkups could be increased

Improving gear shift quality in a PHEV DCT with integrated PMSM

In this paper a hybridized Dual Clutch Transmission (DCT) is presented in which a traction Permanent Magnet Synchronous Motor (PMSM) is mounted on the input side of the even gears. As the motor has high power, it has a high inertia. This leads to increased shift time in Electric Vehicle mode (EV mode). In EV mode, ICE is shut down and both clutches are open and vehicle is driven by PMSM on even gears. Since both off going and oncoming gears are on the same shaft, there will be a torque interrupt during shifts in EV mode. The main focus of this paper is the speed synchronization phase during torque interrupt shifts. Currently the speed synchronization is done by using PMSM only. This sometimes leads to slower shift times and a degraded drivability due to battery power limitations. The speed synchronization can also not be achieved by synchronizers alone as is done in traditional DCTs due to added inertia of PMSM. This paper explains the detailed modeling of synchronizers for simulating speed synchronization times during torque interrupt shifts. The PMSM model is based on a loss map and inertia. The effects of the available power from the battery on speed synchronization are also modelled. A high level modeling is done for rest of the powertrain. Based on simulations, first the increased synchronization time and its main limiting factors are discussed. A prediction model is also created which, before a shift is ordered by high level strategy, creates the speed synchronization trajectories for PMSM and synchronizer. Based on prediction model, a high level supervisory control strategy is developed that will communicate between synchronizer and motor controller to ensure minimum synchronization time based on the limitations in synchronizer and battery.The study can be extended to general treatment of clutchless multi-speed transmissions in electric vehicles and their effects on shift quality in general

Time optimal control of gearbox synchronizers for minimizing noise and wear

Hybrid dual clutch transmissions can reduce fuel consumption and CO2 emissions significantly at a low cost, but they will lead to torque interrupt shifts in electric vehicle mode. To improve the shift quality, the shift time should be minimized and the impacts between the sleeve teeth and the idler gear dog teeth after speed synchronization should also be minimized. Besides creating noise, these impacts are also responsible for delaying the completion of shift and contribute to wear in the dog teeth. This paper presents a time optimal control strategy for mechanical synchronizers in a hybrid dual clutch transmission, which includes constraints such that impacts between sleeve and gear dog teeth are minimized. It is demonstrated how a mechanical synchronizer can be modeled as a double integrator system and how the standard time-optimal control solution of double integrator system must be modified such that it can be applied to mechanical synchronizers. The result is a feedback control strategy that guarantees minimum speed synchronization time and minimum noise/wear in transmission. The performance of the controller is verified by simulation

Feedback Control of Synchronizers for Reducing Impacts During Sleeve to Gear Engagement

This paper presents a feedback control strategy aimed to reduce noise and wear during gearshifts in conventional and hybrid Dual Clutch Transmissions (DCT and DCTH) and Automated Manual Transmissions (AMT). The control strategy is based on a new dog teeth position sensor developed by China Euro Vehicle Technology AB and existing speed sensors in the transmission. During gear shifting, noise is generated by impacts between the sleeve teeth and the idler gear dog teeth after speed synchronization. Besides noise, these impacts are also responsible for delaying the completion of shift and contribute to wear in the dog teeth, hence reducing the lifespan of the transmission. The presented control strategy controls speed synchronization such that the impact between sleeve and idler gear dog teeth, before the start of torque ramp up, is avoided. Since drag torque is an important factor in speed synchronization, this paper also contains an algorithm to identify friction torque coefficient in the transmission. The identification method ensures that the controller adapts to varying conditions without the need for offline calibration. The control strategy is developed for standard automatic gear shifting operations but minor adaptations in the algorithm also make it capable of handling gear shifts requested by the driver. The output signal of the control strategy is acceleration request on idler gear during speed synchronization. To make controller easier to implement and minimize shift time, the acceleration request only has two values, either maximum value or zero. The control strategy is designed in such a way that it can easily be integrated in the existing transmission control software. By applying the control strategy on a detailed simulation model, it is shown that the impacts during gear engagement are significantly reduced