[YesAuto technology] For an SUV model that pays attention to passability and escape ability, the four-wheel drive system is an indispensable configuration. For ordinary cars, the advantage of the four-wheel drive system is that it can obtain better tracking performance on roads with lower adhesion, thereby improving the controllability and safety of the vehicle. In the field of four-wheel drive transmission systems, Magna, the world's third largest auto parts supplier, has a wide range of products. These products have been installed on many models we are familiar with. In this article, we will analyze Magna's main four-wheel drive system products and understand the structure and working principle of these four-wheel drive systems.

● The world's third largest auto parts supplier-Magna

Magna ranked third in the list of the top 100 global auto parts suppliers in 2014, ranking second only to Bosch and Denso. Magna is headquartered in Ontario, Canada, and its business covers the design and engineering of interior systems, seat systems, locking systems, metal body and chassis systems, mirroring systems, exterior systems, roof systems, electronic systems, and powertrain systems Development, testing and manufacturing, as well as vehicle design and assembly.

In the subsequent development process, Magna focused on the automotive industry, implemented a diversified product strategy, and developed into a global top 500 multinational company with multiple listed subsidiaries. In 1996, a company named Long Ma Shen Automotive Seating Co., Ltd. was established, which was also the first joint venture manufacturing enterprise established by Magna in China. Today, Magna has 22 factories and 8 R&D centers and sales offices in China. There are more than 8,000 Chinese employees in China. The Chinese headquarters is in Shanghai.

● Which models of Magna's latest four-wheel drive system are installed?

The Magna four-wheel drive system products mainly introduced in this article include: FLEX4, Actimax, ProActive and eRAD. Among them, FLEX4 four-wheel drive system and Actimax four-wheel drive system can realize different working modes such as time-sharing four-wheel drive, full-time four-wheel drive, and timely four-wheel drive through different adjustments. Among them, the FLEX4 four-wheel drive system has not been installed in mass-produced models, and mass-produced models equipped with Actimax four-wheel drive system will generally be tuned to a full-time four-wheel drive system. The ProActive four-wheel drive system is a timely four-wheel drive system. Generally, it works in two-wheel drive mode. When necessary, the system will automatically switch to four-wheel drive mode and automatically adjust the front and rear axle torque ratio. The eRAD four-wheel drive system uses a motor to drive the rear axle, and we classify it as an electric four-wheel drive system.

The above four four-wheel drive system products belong to Magna's high-end four-wheel drive system product series. In addition to the four-wheel drive system products introduced in this article, Magna also produces other four-wheel drive system components and power distribution units, including the front axle power take-off and rear axle power distribution unit used by the aforementioned Volkswagen Tiguan.

● FLEX4 four-wheel drive system focusing on energy efficiency

The FLEX4 four-wheel drive system uses a motor-controlled multi-disc clutch type limited slip differential for power distribution between the front and rear axles. At the front axle position, the FLEX4 four-wheel drive system has a toothed clutch for completely disconnecting some unnecessary components in the transmission system in the two -wheel drive mode, reducing mechanical losses and improving fuel economy. The design goal of the FLEX4 four-wheel drive system is to obtain fast power distribution between the front and rear axles and to have better fuel economy in the two-wheel drive mode than only the motor-controlled multi-plate clutch limited-slip differential.

The multi-plate clutch limited slip differential of the FLEX4 four-wheel drive system takes about 100 milliseconds from fully released to fully engaged (or from fully engaged to fully released); the toothed clutch changes from fully released to fully engaged (or by The time from fully engaged to fully released) is about 50 milliseconds. The process of switching the FLEX4 four-wheel drive system from four-wheel drive mode to two-wheel drive mode and then back to four-wheel drive mode is as follows: In the four-wheel drive state, release the multi-plate clutch limited slip differential (about 100 milliseconds), and then release it. Open the tooth clutch (about 50 milliseconds), the vehicle switches to the two-wheel drive state; in the two-wheel drive state, engage the multi-plate clutch type limited slip differential (about 100 milliseconds), and then engage the tooth clutch (about 50 milliseconds), The vehicle switches to the four-wheel drive state. The whole process takes about 300 milliseconds.

When the four-wheel drive is switched to the two-wheel drive, the multi-plate clutch limited-slip differential is first released to reduce the load of the toothed clutch and make the separation of the toothed clutch more “easy”; the two-wheel drive is switched to the four-wheel drive In the process, the multi-disc clutch type limited slip differential is first engaged, and the toothed clutch is synchronized by controlling the engine speed, so that the toothed clutch is engaged more smoothly.

● Actimax four-wheel drive system focusing on performance

The Actimax four-wheel drive system is a high-performance system that focuses on the torque distribution speed and response performance of the four-wheel drive system. It is mainly used in high-performance four-wheel drive sports vehicles.

When the vehicle has understeer or oversteer in a curve, the system can decide how to distribute the torque according to the driver's steering and throttle control to help correct the body posture so that the vehicle can safely pass the curve.

● Compact ProActive four-wheel drive system

ProActive four-wheel drive system is a set of four-wheel drive system specially developed for compact cars and mid-size cars. Its development purpose is to improve the handling, driving safety and passability of the above models.

● eRAD hybrid four-wheel drive system

The eRAD four-wheel drive system is a set of motor drive modules located on the rear axle, which cooperates with the engine on the front axle to achieve hybrid four-wheel drive. The motor drive module is equipped with a power disconnect device, which can disconnect the connection between the motor and the rear wheel, thereby eliminating the energy loss caused by the rotation of the rotor driven by the rear wheel under some working conditions.

Article summary:

The tooth clutch of the FLEX4 four-wheel drive system can completely disconnect some unnecessary components in the transmission system in the two-wheel drive mode, reducing mechanical losses and improving fuel economy. This structure is rare in the four-wheel drive systems of other component manufacturers.

Actimax four-wheel drive system is a high-performance system, focusing on the torque distribution speed and response performance of the four-wheel drive system. The “Diff Mimic” active torque control program carried on it will monitor the throttle opening, road conditions, steering wheel angle and other parameters in real time, and dynamically adjust the torque ratio of the front and rear axles, allowing the vehicle to obtain better handling and safety.

ProActive four-wheel drive system is a four-wheel drive system specially developed for compact cars and mid-size cars. The system has the characteristics of compact structure, small size and light weight, and it is convenient to add four-wheel drive function to the chassis of front-drive models to improve the controllability, driving safety and passability of the vehicle.

The eRAD four-wheel drive system is a new attempt by Magna in hybrid four-wheel drive system products. The electric motor arranged on the rear axle can independently drive the vehicle to drive in pure electric mode. More specifically, this rear axle motor module has a toothed clutch similar to the FLEX4 four-wheel drive system for disconnecting the connection between the motor and the rear wheels , which can further reduce the mechanical loss of the hybrid four-wheel drive system.

Magna's four-wheel drive system products have the performance of mainstream products in the industry. In China, Magna's four-wheel drive system products are mainly used in imported models and joint venture brand models. The supporting business volume of self-owned brands is not large. The completion and commissioning of powertrain plants in Tianjin and Changzhou allows Magna to provide solutions and products for its own brands in a more targeted manner, thereby further increasing its market share in China. (Map / text / photo qichezhijia often Qinglin)