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October 19, 2015

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Vehicle transmissions undergo a transformation

Editor’s note:

Manufacturers of key auto parts reconcile the industry’s vision of greener and smarter technology with the reality of budget and technology concerns. China is pursuing pricey innovations like vehicle electrification and connected driving while at the same time trying to improve more established, conventional choices.

At the transmission industry’s huge get-together of this year in China, the Fourth International CTI (Car Training Institute) Symposium on “Automotive Transmissions, HEV and EV Drives” held in Shanghai last month, Professor Ferit Küçükay, chairman of the symposium, discussed the future of the transmission and drive industry in China’s evolution toward sustainable development.

Q: What impact will the networking of vehicles (car-to-x communication) and networking of the drive (connected drive) have on the future development?

A: Networking of the vehicle with the driver, the driving environment and other vehicles in traffic has become one of the mega-trends in the automotive industry. The networking leads to increased vehicle comfort, safety, driving pleasure and efficiency. Vehicle drive and transmission particularly benefit from the networking.

Maintenance and repair: By using wireless communication between vehicles and car workshops, certain malfunctions and sensor failures can be identified by remote diagnosis. Repair services and spare parts can then be sent to the target vehicle. For problems that can be solved with software modifications, the corresponding controller can be updated wirelessly. In addition, we should not ignore the security risk in that wireless communication in a car can be hacked more easily than before.

Operating strategy: Modern vehicles with “advanced driver assistant systems” have multiple environmental detection sensors: ultrasonic sensors, radar systems, laser scanners, cameras and GPS signal receivers. With their help, we can identify the driving environment of the vehicle and the route topology. Depending on the parameters mentioned, a longitudinal velocity profile (vehicle speed over distance or time) can be estimated, which can then be used by numerous drive and transmission functions. The knowledge allows the operating strategy of the drive to adapt optimally. In particular, driving velocity known in advance can be used for the predictive intelligent operating strategy. With its help, the engine and the transmission can be controlled and operated so that the fuel and energy consumption is reduced and comfort and safety are increased at the same time. It also provides temporary emission-free driving in environmental zones by route knowledge, which represents another focus for the intelligent management of the drive.

Q: What are the challenges and opportunities for transmission development to facilitate the trend of vehicle electrification to reduce fuel consumption and smog levels?

A: Traffic-related smog will be reduced by the same amount as fuel consumption is reduced. However, it must be noted here that a large part of smog in mega-cities results from electricity generating and thermal power stations.

Reduction of fuel consumption is a central topic of vehicle development worldwide. Transmission plays a central role. The internal combustion engines are expected to remain in use for the next 30 years because the development of practical “new energy vehicles” will take many years to complete.

The development of efficient drives with internal combustion engines is therefore of significant importance in the long term. An effective approach to improve the efficiency of conventional drives is hybridization by integrating one or two electric motors in the transmission, which creates the so-called “active transmission.”

That has the following characteristics and components: electric motors, power electronics, actuators, sensors and control units. Communication with all modules within a vehicle, especially with the drive, chassis, driver assistance systems and infotainment is a prerequisite for the performance of all “active” tasks, such as optimizing traction (driving performance), drivability (comfort and dynamics), energy consumption, range and road safety.

In order to perform these tasks, an active transmission can shift the gears by using actuators, disconnect or connect one or both driving machine(s) in pulling or pushing operations.

Due to the features listed above, active transmissions will be used increasingly in hybrid vehicles and plug-in hybrid vehicles, which have an electric range between 20 and 50 kilometers. In comparison with conventional vehicles, the fuel consumption reduction can reach 20 percent to 30 percent with hybrids and up to 70 percent with plug-ins.

Q: Will the traditional drive system be able to satisfy the demands of energy-saving and carbon emission reduction?

A: Traditional drive and transmission systems having naturally aspirated engines and four or five speed transmissions couldn’t meet the requirements of today’s fuel consumption and CO2 emissions regulations. Only downsized direct injection internal combustion engine with turbo charging, in combination with seven to 10 speed automatic transmissions, will be able to fulfill customer expectations as well as legal regulations by 2020 up to the C car segment. The bigger vehicles like SUVs need hybrid drive systems in the future.

There has been big progress in the transmission development in the last 15 years. The number of gears of automatic transmissions has increased from four to 10. Besides, all modern transmission concepts are either already electrified by installing an electric motor in connection with the electrification of the drive system, or prepared for the electrification in a later time period. Their efficiency is also much higher than the traditional ones.

In the future, it can be assumed that the number of gears will be reduced in electrified active transmission.




 

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