(1) Part-time four-wheel drive is mostly used for off-road vehicles. Simply put, two-wheel drive and four-wheel drive need to be chosen by themselves. Basically, it is a four-wheel drive based on rear drive. There is no speed difference before and after, with torque amplifier. I won't say much about this. Does not meet your requirements. It represents the model and the last herder.
Viscous coupling
Central differential of
(2) Four-wheel drive is mostly used in urban SUV models in time, and most of them are central differential with multi-disc clutch structure, and a few of them use viscous coupling. Most of them are four-wheel drive models based on the predecessor. After the front wheel slips, the multi-disc clutch is automatically pressed to form a four-wheel drive to get out of trouble. This is rarely used now.
Multi-disc clutch central differential, the original timely four-wheel drive, and later full-time four-wheel drive all adopt this structure.
(3) But gradually developed, the multi-disc clutch can maintain a certain compression force at any time. Usually about 5% of the power can be transmitted to the rear wheels, which is called full-time four-wheel drive. When the front wheel slips in bad road conditions, and the cornering acceleration and linear acceleration are carried out, it will automatically control to further compress multiple clutches to transmit power according to the situation, and the maximum power distribution of the front and rear axles can reach 50:50. Of course, some models will also have button control. You can choose to intelligently allocate full-time four-wheel drive or completely disconnect to form two-wheel drive to save fuel, and some can also choose to lock in advance at 50: 50 to get out of trouble. Nowadays, most urban SUVs have this multi-piece clutch structure. This structure has many advantages, first of all, it is cheap, simple in structure, low in failure rate and simple in operation, which can meet the road conditions and needs of most customers and also has low fuel consumption. There are also Audi Q3 and quattro full-time four-wheel drive models, which are also the structure of this multi-disc clutch. The new Q5L is not a Towson central differential.
Of course, there are several full-time four-wheel drive models, both off-road vehicles and urban SUV models. Like Audi Q5' s full-time four-wheel drive, it uses the Towson self-locking central differential, and the old Prado also uses the Towson central differential. There is also Audi's new generation crown differential, which represents the model RS 6. There is also an open differential as a central differential, representing Mercedes-Benz G-Class. Of course, its transfer case has a tooth-embedded differential lock, which can lock the central differential if necessary. But I always think that only this kind of differential that can really realize the differential speed between the front and rear axles is a real differential.
Freeman and Qi Jun are considered as urban SUV models with better off-road performance.
As the name implies, full-time four-wheel drive is always a four-wheel drive. When there is no two-wheel drive, there are many models that meet this condition, but few models with a price above 200,000 have full-time four-wheel drive. Some people will say that there are many four-wheel drive models at this price. Why not? In fact, this is a misunderstanding of many people, thinking that a car with four-wheel drive function is a full-time four-wheel drive. In fact, there are many models with four-wheel drive system, but there are not many full-time four-wheel drive cars.
Four-wheel drive systems are divided into three categories: part-time four-wheel drive, timely four-wheel drive and full-time four-wheel drive. Generally, hard-core off-road vehicles adopt part-time 4wd system. This four-wheel drive structure usually adopts two-wheel drive. Only when the four-wheel drive is needed can the four-wheel drive be connected manually. The power output between the front and rear axles is connected through a toothed differential lock, and the front and rear axles are rigidly connected. Shepherd, Mercedes-Benz G, Land Rover Defender and FJ Cool Road Ze all have such designs.
Most of the more than 200,000 urban SUVs use a timely four-wheel drive system. The central differential of this four-wheel drive system adopts a multi-plate clutch structure. In general, it is usually front-wheel drive. Only when the front wheel loses its driving force will the four-wheel drive system intervene. One type of differential lock can be controlled manually, such as Outlander, Qi Jun and Fangrong. Both have manual locking function, but in the final analysis, this model still adopts a timely four-wheel drive system.
The full-time four-wheel drive system has no two-wheel drive option, and it is always a full-time four-wheel drive. There are many models designed in this way, such as Prado in the Middle East, Land Patrol, old Q5, Q7, BMW X3, X5, X6, etc., but only Subaru and Road Shocker can satisfy more than 200,000. You can consider these two paragraphs.
Since the question emphasizes full-time four-wheel drive, the key point is to answer with full-time four-wheel drive. As for the contrast between power and space, interior and appearance, I won't go into details.
Full-time four-wheel drive is the most suitable driving model, but limited by the technical threshold, many car companies are unable to produce full-time four-wheel drive, and most of them adopt timely four-wheel drive. Generally speaking, although timely four-wheel drive will cause some instability caused by out of control when driving on wet roads or at high speed, it is still far from full-time four-wheel drive. Because the full-time four-wheel drive can continuously distribute the torque according to the grip, and the four wheels have the grip continuously, even if some wheels slip, the other wheels will still have the driving force, which can avoid the out-of-control phenomenon caused by automobile slip to a certain extent and increase the high-speed stability and tracking performance. The following contents are recommended as appropriate:
With a level of more than 200,000, Subaru is definitely worth considering. In addition to brz, Subaru is a full-time four-wheel drive model, which has persisted for decades. Subaru's XV, Forester and Outback's four-wheel drive have the same structure and similar functions, all of which are X-mode, which can increase the ability to get out of trouble at low speed. From the level of view, XV belongs to small city SUV, forester belongs to compact city SUV, and Outback belongs to medium-sized travel crossover.
Subaru's current models all adopt ACT-4 full-time four-wheel drive system based on multi-disc clutch. This four-wheel drive system is a four-wheel drive system based on the vertical layout of the engine, which uses an electronically controlled multi-disc clutch as the central differential to play. In daily driving, the front wheel characteristics are biased, and the power distribution ratio of front and rear wheels is 90: 10. At different speeds, the torque distribution ratio of front and rear wheels can be automatically adjusted, and the power distribution ratio of front and rear axles is 50: 50 at the limit.
After the unique X-MODE mode is turned on, the rear axle can get an additional 25% torque distribution, which is similar to the effect of locking the middle difference. When the vehicle speed exceeds 40km/h, the lock will be automatically released.
Generally speaking, Subaru's full-time four-wheel drive has good high-speed stability and strong ability to get rid of difficulties at low speed.
Volkswagen's four-wheel drive system actually uses Borgwarner's Hande five-generation four-wheel drive system, which is adopted by all Volkswagen models except Touareg. This is a four-wheel drive system based on transverse engine layout. Some people say that this four-wheel drive system can't be regarded as a full-time four-wheel drive, because only 5% of the torque in daily driving is distributed on the rear wheels, which is better than nothing.
However, if we simply look at the form of driving, Hande V really stepped into the threshold of full-time four-wheel drive because of only 5% torque. In fact, it is more difficult to realize full-time four-wheel drive with horizontal engine layout, and it is necessary to change the transmission direction through bevel gears, which will reduce the transmission efficiency. However, the reason why Hand V keeps 5% torque to the rear wheel is to improve the dynamic response efficiency.
Structurally, the structure of this four-wheel drive system is relatively simple. It uses an independent centrifugal electro-hydraulic oil pump to control multiple clutches to realize the power distribution of the front and rear axles. Because it can output at least 5% power to the rear axle, the electro-hydraulic oil pump is always in a pressed state, which makes the response efficiency of this four-wheel drive system faster. It can output 50% power to the rear axle at most. But relatively speaking, because this system has no independent cooling system, it will lead to overheating when it is used in high intensity.
In fact, China doesn't have its own four-wheel drive technology at present, and all four-wheel drive products mostly adopt Borgwarner's products, while most four-wheel drive systems in the world have corresponding patent barriers.
Therefore, BYD's Tang DM is definitely the product of overtaking in corners. Tang's unique front and rear "three engines and four-wheel drive" can realize the automatic control of front and rear axle power distribution ratio, bypassing foreign patent barriers. The engine of this system does not directly participate in driving, but plays the role of range extender. Personally, I look forward to the power and fuel consumption performance of Tang DM-I.
Don't just focus on the four-wheel drive structure of SUV. Some four-wheel drives are just to improve the handling of vehicles on wet roads, and the performance of four-wheel drives from different manufacturers is completely incomparable. For example, BMW's four-wheel drive structure is entirely to improve the sports performance of vehicles, and Audi's full-time four-wheel drive used in R and RS series is also to improve sports and handling. JEEP's Grand Cherokee off-road ability is good.
The price of 20W is basically not used for full-time four-wheel drive models, and the bare car of its own brand with full-time four-wheel drive structure is also around 25W, that is, D90 of Datong Roewe and RX8 of Haval, H8 and H9 (in fact, full-time four-wheel drive manufacturers only change themselves into timely four-wheel drive models because they can choose four-wheel drive modes).
Joint venture brands include Jiangling Ford's Roadwalker (four-wheel drive structure is exactly the same as Harvard's) and Chevrolet's pathfinder Jeep's commander-in-chief.
200,000-hour four-wheel drive SUV, it is estimated that only Subaru forester!