How does Geely compete with Toyota's hybrid technology in the face of patents?

While traditional internal combustion engine cars are pursuing 8AT, 9AT, 10AT... and more and more gearboxes, hybrid technology has actually already left traditional gearboxes aside. While the fuel economy is better than that of internal combustion engines, it also achieves the same stepless speed change capability as CVT gearboxes. The most representative of these is Toyota's hybrid technology. However, as a Chinese brand, Geely does not think that this is exclusive to foreigners. Now, they have demonstrated a new hybrid technology...

● Collaborator or competitor? 

Before we learn in detail how Geely competes with Toyota's technology, let's first talk about the story behind them. Yes, there is another layer of relationship behind the hybrid technology.

The story should start with the NiMH battery of Toyota Prius. We can see that even today when lithium batteries have become mainstream, Toyota still insists on the use of NiMH batteries. For example, the latest fourth-generation Prius provides two solutions: lithium battery pack and NiMH battery pack. Nowadays, the NiMH battery supply for domestic Toyota hybrid models mostly comes from a company called Corun.

In 2011, the growing Corun company acquired Panasonic's Shonan Battery Factory in Japan, which provided batteries for the first generation of Prius. On the first day of 2014, Geely Auto and Corun announced that they would "be together" and set up a new company to jointly develop the CHS (China Hybrid System) hybrid technology platform, which has certain scalability and can provide assembly technology for oil-electric hybrid (HEV) and plug-in hybrid (PHEV) models. Geely holds a 49% stake and Corun holds a 51% stake, so for Toyota supplier Corun, this is a challenge to its own client! Although the CHS hybrid technology developed by Geely and Corun is still one step away from mass production, the two partners, Toyota and Corun, have obviously embarked on the road of technological competition.

●  What’s so great about Toyota’s hybrid technology?

We know that Toyota is the earliest manufacturer to research hybrid technology, and it was the first to mass-produce a hybrid car, the Prius, in 1997. As Toyota's hybrid technology continues to accumulate, its E-CVT technology that can achieve continuously variable speeds is becoming more mature.

" The traditional gearbox has been cancelled? " When we put aside Toyota's hybrid powertrain, you will find that its mechanical structure is not as complicated as we imagined, and its powertrain volume is not much different from that of traditional internal combustion engine models. This system is mainly composed of an engine, two electric motors and a set of planetary gear sets. Although the traditional gearbox structure is gone, it can achieve continuously variable speed like a CVT gearbox, so Toyota calls this system an E-CVT continuously variable speed mechanism.

" How to change speed without a traditional gearbox? " The core of Toyota's hybrid power lies in the power coupling principle of this set of planetary gears, which ultimately outputs power to the main reducer and wheels through the ring gear. Among them, the motor 1 not only plays the role of a starter and generator, but also can function as a speed regulator through the sun gear connected to it, thus realizing the stepless speed change function.

In fact, Toyota's E-CVT is not complicated in terms of structural principle, but the difficulty lies in the control logic design of this hybrid system, such as when to enable pure electric mode, when the engine intervenes for hybrid drive, when to charge the battery pack, and how to distribute torque, etc. If there is a problem with the control logic under any working condition, Toyota will not be able to achieve the energy saving pursued by hybrid power, even if the 1.8L engine code-named 2ZR-FXE on the fourth-generation Prius has achieved a fuel thermal efficiency of 40%. Therefore, Toyota's ability to achieve such hybrid technology is entirely due to its rich technical accumulation in the past 20 years.

It is worth mentioning that it is impossible for any manufacturer to directly copy Toyota's E-CVT technology in a hybrid structure, because Toyota has already applied for it as its own patented technology. So how can Geely catch up with Toyota's hybrid technology?

●  Geely goes to great lengths to circumvent Toyota’s hybrid technology patents. Why?

Judging from the current development of new energy in China, since the domestic charging pile system is not yet perfect, the range of pure electric vehicles has been criticized. Therefore, Geely must have the ability to develop hybrid vehicle technology, and creating hybrid vehicles has become an important development direction for them.

Since the threshold for creating hybrid technology similar to Toyota is so high, why does Geely still develop hybrid technology based on planetary gear sets? The reason is that Geely believes that this hybrid structure has more advantages in overall performance than the hybrid structure that relies on clutch to intervene in the torque of the electric motor (such as the hybrid technology equipped in the Hyundai Sonata 9); in addition, the way of coupling the engine and the electric motor through planetary gears will not produce a sense of frustration and can achieve stepless speed change.

Therefore, he sought cooperation with the battery technology expert, CRRC, and began the research and development of hybrid power systems based on CRRC's advantages in battery technology and battery system energy management.

In addition, we saw on the website of the State Intellectual Property Office that Geely has applied for such a patent. Simply put, its essence is not much different from Toyota's hybrid power. The only feature is that Geely bypassed Toyota's technical patent by adding a double-row planetary gear set (Toyota's power distribution mechanism is an ordinary single-row planetary gear set) and a clutch.

The CHS hybrid technology developed by Geely and CATL consists of an engine, two electric motors, a double-row planetary gear set and multiple clutches. Compared with Toyota's E-CVT structure, it has more parts and a more complex structure.

"What are the advantages of CHS hybrid technology?" Compared with Toyota's E-CVT technology, the CHS hybrid technology jointly developed by Geely and Corun is more complex in structure. The advantage brought by this is that the addition of double-row planetary gear sets and locking clutches makes the control mode of the hybrid system more free, thereby reducing the difficulty of coupling control of the engine and the motor. In addition, the double-row planetary gears have a wider gear ratio range than single-row planetary gears, which can reduce the speed requirements for the motor to a certain extent. At the same time, the disadvantages are also more obvious, that is, the reliability and durability tests brought about by the increase in structural complexity will increase exponentially.

●  How does the CHS hybrid system drive the vehicle?

1. Pure electric stage

During the starting phase, vehicles equipped with this hybrid system will be completely transformed into pure electric vehicles. At this time, the power to propel the vehicle to start comes entirely from an electric motor, giving full play to the economic advantages of pure electric drive.

Motor 1 drives the reduction gear through the planetary gear set, and then drives the vehicle. At this time, since the clutch between the engine and the planetary gear set is disconnected, the energy consumption caused by the engine's reverse drag is eliminated. After the car starts, if the ring gear of the planetary gear set is to output power to the outside steplessly, then the motor 2 that plays the role of speed regulation must be used. It changes the transmission ratio between the planetary gear and the ring gear, thereby realizing the stepless speed change function. In addition, the forward and reverse movement of the vehicle is also determined by the forward and reverse rotation of motor 2.

2. Hybrid drive stage

On the one hand, due to the limited speed range of the motor 1, the vehicle cannot reach a higher speed in pure electric mode. On the other hand, in order to make up for the lack of torque at this time, the engine has to be called to work when the vehicle reaches a certain speed. We know that for ordinary internal combustion engine models, if you want to make the vehicle move, the first step is to rely on the starter to drag the engine crankshaft to rotate, and then ignite the engine to work. However, this hybrid system is completely different.

- How to start the engine while driving?

During driving, the motor 2, which regulates the speed, can also play another key role - the starter. The clutch between the engine and the double-row planetary gears is engaged through the hydraulic control system, and the locking clutch between the double-row planetary gears and the motor 1 is released. The engine is then connected to the planetary gear set through the planetary carrier connected to it. At this time, the motor 1 maintains the original output power state, and only the rotation of the motor 2 is needed to drive the engine to work, converting from pure electric to hybrid drive mode.

- How to charge the battery pack while driving?

When the engine is running, it can not only further increase the vehicle speed, but also, according to the torque distribution principle of the planetary gear, when the battery pack is low on power, part of the excess torque can also charge the battery pack. Yes, at this time, the motor 2 has played its third role - generator. The engine will not charge the battery at all times, provided that the engine is kept in the speed range with the best fuel economy, and the extra energy will be added to the battery pack.

- How to improve economy when cruising at high speed?

When the vehicle is running at high speed, in order to improve the transmission efficiency of the system, the locking clutch located on the right side of motor 2 will lock motor 2 and the sun gear connected to it. The power source is only provided by the engine and motor 1, reducing the operation of some gears in the system, thereby improving mechanical efficiency.

3. Braking energy recovery stage

When the vehicle decelerates and brakes, the hybrid system will recover kinetic energy into the battery pack through motor 1 and motor 2.

In addition, this CHS hybrid system can theoretically charge the battery pack at idle speed. The principle is to lock the sun gear in the planetary gear through the locking clutch, the engine drives the ring gear in the planetary gear, the ring gear drives the planetary gear, and then rotates the motor 1 connected to the planetary gear. At this time, the motor 1 becomes a generator to charge the battery pack.

● Summary

Geely's vision for the CHS hybrid technology platform is to serve all Chinese automakers, just like the name of this hybrid system, China Hybrid System. It is based on such an open mindset that they have attracted other automakers. For example, in February 2016, Changan Automobile Company announced that it had reached a cooperation agreement with Geely and CRRC.

Of course, this new hybrid system is still far from mass production. Although Geely and Corun have bypassed Toyota's technical patents in terms of hybrid system structure, they can theoretically compete with Toyota in terms of function and performance, but the premise is that Geely's engine technology can keep up and not drag down the overall fuel economy. For example, Toyota can increase the thermal efficiency of gasoline engines to 40% through exhaust gas recirculation (EGR) and Atkinson cycle technology. In addition, although the control difficulty of the hybrid system can be reduced to a certain extent by adding mechanical components, the reliability and durability issues that come with it should not be underestimated. In short, Geely's step in hybrid technology is very worthy of our praise, and we still need to continue to work hard in the future.