In recent years, with the growing market demand, more and more pickup truck products have been launched in China. Regardless of the appearance and interior, or the overall performance, they tend to be more passenger vehicles, and IKEA is the development direction.
Changan Kaicheng F70 has received wide attention from the market since its launch at the end of October. Is this brand-new pickup truck with “joint adjustment of Chinese and foreign chassis performance development teams” as the publicity point and highlighting the performance of “comfort, load carrying and safety” really as advertised? A few days ago, we came to Chongqing Changan Automobile Global R&D Center to find out.
Let’s start with some background information.
Created by Citroen chassis masters, jointly tuned by Changan R&D Center in Detroit, USA
The chassis of Changan Kaicheng F70 is built by Citroen chassis master, and jointly tuned by Changan American Detroit R&D Center and Changan Automobile Global R&D Center. It also incorporates more than ten years of tuning experience from the chassis technical experts of the Changan Detroit R&D Center in the United States on hard-core off-road chassis such as Dodge and Raptor.
Chassis Performance Exploration
Without exception, domestic pickup truck chassis adopt non-load-bearing structures, and many models are highly similar to each other. The whole vehicle of Changan Kaicheng F70 is also a non-load-bearing body, adopting a closed trapezoidal structure with 2 longitudinal beams + 7 beams, made of high-strength tension steel, which has good bearing capacity, absorption and resistance to torsion.
In terms of frame size, the longitudinal beams are lengthened by 93.5mm, and the crossbeams and longitudinal beams are widened by 71mm to achieve a vehicle length of 5330mm, a width of 1930mm, and a height of 830mm. Carrying capacity.
The front suspension adopts double-wishbone independent suspension with large lateral rigidity, which can effectively absorb the lateral force on the tires, prevent the vehicle from rolling, and improve the grip of the tires. Universal application. The rear suspension is a leaf spring non-independent suspension. To meet the load requirements and take comfort into account, it is necessary to precisely adjust the rear damping and leaf spring matching. According to reports, during the debugging process, the engineering teams of Changan America, France, and Changan Automobile have conducted many verification tests in order to achieve the optimal state.
In terms of materials, world-renowned suspension system suppliers are used. For example, the shock absorber is produced by Tokiko, the upper and lower swing arms of the front suspension are produced by Somic, and the stabilizer bar is produced by Tianjin Dagang, etc., through repeated fine-tuning , so that the suspension system can achieve optimal matching.
Similarly, the steering system adopts international and domestic excellent suppliers Korea Mando power steering pump and Jingzhou Henglong power steering gear. The hydraulic steering system has the characteristics of smooth feel, clear road feeling, high reliability and low maintenance cost. After a series of adjustments, the problem of heavy steering force at low speeds has been fully optimized, while taking into account the stability of high-speed steering, which has greatly improved the driving experience of users in off-road, urban transportation and high-speed driving scenarios.
Due to the greater load, the braking and safety performance of pickup trucks is particularly important. In terms of braking performance, it was developed in accordance with Changan’s braking performance family requirements, and comprehensive CAE simulation calculations were performed in terms of performance, braking temperature rise, parking performance, braking vacuum, etc., and the final optimal solution was selected. After the plan was determined, it took 24 months to experience the high temperature of 50°C in Turpan, Golmud at an altitude of 5000m, and Heihe at minus 40°C. And other performance matching development. In addition, in terms of braking performance, the whole series is equipped with MANDO’s new advanced ESP body electronic stability system as standard, with nearly 20 electronic control functions such as ABS, TCS, ESC, HBA, HHC, HDC, TSC, etc. Active braking and other aspects have comprehensively improved intelligence and safety performance.
The body frame and shock absorber bushing adopt flexible connection matching test, which has good vibration isolation performance and can effectively restrain shock and vibration, bringing users a good driving comfort experience. In addition, the engine bushing is suspended and connected. This kind of bushing matching can effectively restrain the excess vibration when the vehicle passes the speed bump or potholes. In addition, the stiffness precision is optimally matched and debugged for the swing arm bushing to achieve a good vibration isolation effect, making the control response more sensitive, and effectively avoiding the much-criticized steering wheel vibration problem of traditional pickups.
In terms of the overall chassis structure, all the frames at the bottom of the car, including the inner side of the wheel arches, are equipped with resin guards, and are evenly sprayed with a protective coating, which plays a very good protective role.
After having a preliminary understanding of the chassis structure of the Changan Kaicheng F70, we came to the comprehensive automobile test site in Dianjiang, Chongqing. Next, through extreme tests such as elk test, sine test, and fixed circle test, as well as high-loop, climbing, and comfortable road conditions, etc., we will fully understand and more intuitively experience the “carrying capacity” of the Changan Kaicheng F70 chassis. “, “Driving Safety” and “Comfort” three performances.
The first is the elk test, which originated in Sweden. Because elk with a body weight of up to 300 kg will always appear on the road inadvertently, and after colliding with a high-speed car, it will directly hit the driver’s cabin and cause serious injury and death to the driver, but it will not trigger the protection of the airbag. Therefore, the elk test is mainly used to test the ability of the car to avoid obstacles, and has become an important standard for measuring the safety of a car in the world.
The test vehicle is equipped with body height position sensor, steering wheel steering angle sensor and three-axis vehicle speed sensor. Repeated elk test and data analysis, and then repeated adjustment and improvement, so as to improve the vehicle’s loss of control limit and the handling and stability of the chassis. , to ensure that the Changan Kaicheng F70 can be “opened without turning over”.
The ESC sine stagnation evaluation test tests the ESC performance of the vehicle through the “sine stagnation” test of driving left, right and then returning to the center. In this Changan Kaicheng F70 sinusoidal stagnation test, two sets of sinusoidal stagnation steering input tests were carried out according to the vehicle with a curb weight of 1588 kg-2722 kg equipped with a standard anti-roll frame with a maximum mass of 32 kg and a maximum moment of inertia of 35.9 kg·m². Among them, the first half cycle of one group of tests is performed in a counterclockwise direction, and the first half cycle of another group of tests is performed in a clockwise direction. During the “sine stagnation” test, the automatic steering device ABD steering robot is used to precisely control the angle and angular velocity of the steering wheel; at the same time, RT series high-precision gyroscopes are used to measure parameters such as yaw angular velocity and side slip angle of the center of mass. The side slip angle of the center of mass is used as the core evaluation parameter of the ESC performance test. The smaller the side slip angle of the center of mass, the better the ESC performance.
The fixed circle test is in a circular test site. The vehicle draws a circle counterclockwise at a high speed, which is similar to the car scene of fast turning, U-turn, and driving around the island in the simulated real road. The test shows that starting from this point and restarting The time it takes to get back to that point is the grade for the project. It is used to detect the matching degree of the vehicle’s body stability system and traction control system (TCS for short), and these two active safety systems play a vital role in driving safety.
This time, the driver will drive the Changan Kaicheng F70 along a circle with a radius of about 61m at a corresponding speed of lateral acceleration of 0.05g, that is, the driver will speed up a little bit from the start until he feels that the vehicle has reached the edge of slipping and non-slipping. And keep driving at this speed and push the car to the limit on cornering speed.
In the following time, we also conducted a short test drive and test ride experience.
The road comfort test area is distributed with various road conditions such as cobblestone roads, gravel roads, steel cable roads and Belgian roads, so as to test the driving comfort performance of vehicles under different landforms. Through the test drive, you can feel that Changan Kaicheng F70 has relatively clear road feeling feedback when driving, and the chassis suspension can better filter out part of the vibration. There is no obvious bumpy feeling in the car, and the vehicle shows high comfort. .
In the actual driving process, the steering feel is relatively smooth, and it is not heavy at low speeds. At the same time, as the speed increases, the steering wheel will gradually become calm. Under the action of torsion on the undulating road, the body and chassis have no abnormal sound.
The Changan Kaicheng F70 we tested is equipped with a 2.5T turbocharged engine from Isuzu. Thanks to the peak torque of 360Nm and the better grip of Giti AT70 tires, the non-paved road performance is very calm and powerful. The four-wheel drive model adopts BorgWarner’s time-sharing four-wheel drive system, which has a low-speed four-wheel drive mode and Eaton rear axle differential lock, which makes it easier to deal with sideslip slopes or 60-degree slopes. Therefore, to a certain extent, Changan Kaicheng F70, which has strong passing performance and off-road capability, has no problem in off-road use.
The high-speed ring road is a test track with relatively high technical content in the comprehensive test field. In the experience of the high-speed ring road, when Changan Kaicheng F70 is driving on the high-speed ring road at a speed close to 160km/h, the vehicle’s stability and NVH performance are very good. it is good. The diesel engine at high speed has a more obvious sound coming into the car, and the road noise and wind noise are well controlled.
With the continuous growth of market demand, the level of car manufacturing of self-owned brands is also advancing day by day, and pickup trucks are becoming more and more passenger cars. Through this chassis exploration tour, we can feel that after the joint research and development of Changan and PSA, the chassis of Changan Kaicheng F70 does have excellent performance in terms of safety, handling and comfort.
Under the trend of urbanization of more and more SUV models, pickup trucks are gradually taking on the hard-core off-road function due to their unique body structure and performance advantages. Therefore, off-road enthusiasts based on hard-core off-road needs may wish to consider more pickup truck models, which are both suitable for business and IKEA and more off-road. Of course, with the continuous adjustment of the pickup truck policy, the car environment will be better in the future.