Another big news Gehlfa K7 real vehicle challenge wind tunnel test


For Jianghuai heavy trucks across the K7, I believe you have a lot of card friends have been concerned about. Geerfa made a breakthrough in K7's high-end quality, powerful functions and intelligent technology applications to create outstanding vehicle performance. It identified a total of 20 performance items and 1270 performance indicators, becoming a Gehlfai heavy truck. History has spanned the pinnacle.


Recently, there is a big news across the K7 - wind tunnel experiments, the following for everyone to popular science!
What is a wind tunnel experiment and why is it so cattle?

The wind tunnel experiment was originally used in the aviation field and is an indispensable link in the development of an aircraft. According to the principle of relativity of motion, by artificially generating and controlling the air flow, the flow of gas around the object can be simulated and the effect of the air flow on the object can be measured.



Wind tunnel is the most commonly used and most effective tool for aerodynamic experiments. Through the wind drag coefficient measured by the wind tunnel test, the air resistance of the car when it is running can be calculated. This is closely related to the fuel consumption of the vehicle and the high-speed driving safety. With the development of industry, wind tunnel technology has also begun to be applied to the development of some passenger vehicles. However, the wind tunnel experiment of heavy truck products is not so easy, and domestic manufacturers are rarely involved.

What is automotive aerodynamics and what is its use?

Automobile aerodynamics is a branch of aerodynamics. It mainly studies the relationship between the interaction forces between the car and the surrounding air when they move relative to each other. It is generally said that the vehicle will disturb the surrounding air during driving. The vehicle aerodynamics is to find out how the air is disturbed and what happens when it is disturbed.



For flat-head heavy trucks, both the front and the side, the contact area with the air is greater, and the resistance to it is also increasing. Therefore, it is very important to study the aerodynamic performance of trucks. In addition, in addition to the resistance generated by the air, it also brings some benefits, such as cooling the engine, defrosting and defogging, cab cooling, cab heating, and so on.

In the “automotive wind tunnel”, the huge artificial wind can simulate the air resistance, noise, and thermodynamic status encountered in various driving environments, thereby testing the safety and handling stability of the prototype vehicle and minimizing the number of cars in motion. The loss of momentum provides conditions for designing more energy-efficient and beautiful cars.

To overcome difficulties, to overcome the K7 challenge heavy truck aerodynamics

Compared to passenger cars, domestic aerodynamic development of heavy trucks can be said to be a blank space. Due to the small circle, few opportunities for technical exchanges, lack of accumulated experience, and lack of hardware conditions, the development of domestic aerodynamics of heavy trucks has been constrained by many aspects. Many truck manufacturers also pay more attention to the reliability, power performance, and production cost of the entire vehicle when developing new vehicles, ignoring the aerodynamics of the vehicle.



In order to achieve better performance across K7, the JAC Technical Center cooperates with the Austria Magna Steyr Engineering Center and the Automotive Engineering Research Institute of China Automotive Technology and Research Center to deeply integrate the domestic and international aerodynamic performance development resources, including China and the United States. A high-level, global aerodynamic joint R&D team improved K7 across three stages.



From external structures such as ceilings, sun visors, air curtains, and grilles, to the interior of the nacelle, R&D personnel have optimized the K7 across the entire area. After the optimization, Geerfa overcomes the K7 air resistance by 15%, which reduces the fuel consumption by about 7%. It also improves safety while saving energy. Even at high speeds, the vehicle's attitude remains very stable.
JAC Gehlfa K7, how exactly will it play in the wind tunnel experiment? What kind of stunts did the R&D staff use during the optimization process? What kind of surprise will be brought about by the qualitative leap that the improved Geerfa made across the K7? Wait and see!










Tapered Roller Bearings

 

Tapered roller bearings are mainly suitable to carry combined load---radial load and as well as axial load; While steep angle tapered roller bearings (27°-30°) can carry the combined load dominated by the axial load. The tapered roller bearings are separable bearings, their internal assemblies and outer rings can be mounted separately; the radial clearance and axial clearance can be adjusted when mounting and interference fits are also allowed.

Structures

1.30000 type single-row tapered roller bearings

This type of bearings can accommodate the axial displacement and axial load on one direction on the shaft or housing. An additional axial force will be generated under the action of radial load, so the outer ring and inner ring inside the two bearing slewing should be mounted with their end faces with same name opposite each other. When applied separately, the applied axial force must be larger than the additional axial force.

2.350000 and 370000 types of double-row tapered roller bearings

These types of bearings comprise one double-raceway outer ring (one double-raceway inner ring) and two inner rings (two outer rings). There is a spacer between the two inner rings (two outer rings), To change the thickness of the spacer can adjust the bearing clearance. They can carry radial and double-direction axial load simultaneously.

3. 380000 type four-row tapered roller bearings

This type of bearing adopts two double-raceway inner rings, one double-raceway outer rings and two single raceways. There are spacers between inner rings and outer rings used for adjusting bearing clearance. They can accommodate large radial load. But their limit rotational speed is low so they are mainly applied to heavy-duty machines such as rolling mills.

Cage materials

Tapered roller bearings generally adopt steel sheet cages, when with too large sizes, use welded steel sheet cages or steel pinned solid cages.

Permissible tilt angle

Generally, inclination is not allowed between the shaft and the housing on the tapered roller bearings. If any, it should not exceed 2'.

Tolerance and Clearance

Generally, the tolerance classes of tapered roller bearings is P0, also can produce higher tolerance classes bearings according to the requirement of users. The tolerance value is showing in the section [the tolerance of rolling bearing".

Users can adjust for practical clearance for the single-row tapered roller bearings according to different demands. The radial clearance of double-row and four-row tapered roller bearings is showing in the table 1.

Dynamic equivalent radial load

Single-row tapered roller bearings:

                Pr = Fr   When Fa/ Fr≤e

         Pr=0.4Fr+YFa     When Fa/Fr>e

When applying single-row tapered roller bearings in pairs, the additional axial force must be counted when computing the equivalent dynamic load of the bearings. The axial load magnitude is influenced by mounting methods and the applied axial load and the detailed computing method is same as angular contact Ball Bearings.

The additional axial load on the single-row tapered bearings can be approximately computed with the equation below:

             S=Fr/2Y

Double-row tapered roller bearings:

Fa/Fr≤e    Pr=Fr+Y1Fa

Pr=Fr+Y1Fa    When Fa /Fr≤e

Fa/Fr>e     Pr=0.67Fr+Y2Fa

Pr=0.67Fr+Y2Fa   When Fa/Fr>e

Static equivalent radial load

Single-row tapered roller bearings:

P0r=0.5Fr+Y0Fa   

If P0r<Fr, take P0r=Fr

Double-row and four-row tapered roller bearings:

P0r=Fr+Y0Fa  

In the equation:

Fr Actual radial load of the bearing

Fa Actual axial load of the bearing

e.Y.Y1.Y2.Y0  see the bearings dimension table.

In order to prevent damaging sliding generated between the rollers and raceway, a minimum radial load must be acted on the bearing. The calculating formula is:

  Frmin=0.02C   

In the equation: Frmin     Minimum radial load

                 C       Basic dynamic radial load rating 

Tapered Roller Bearing

Single Row Tapered Roller Bearing,Double Row Tapered Roller Bearing,Four Row Tapered Roller Bearing

Xibei Bearing Co.,Ltd. , https://www.nxzjck.com