Besides braking energy, there is more to do with automobile energy recovery

Traditional cars have serious energy waste, such as the waste of car kinetic energy during braking, the energy dissipated by the suspension when the car vibrates, and the heat taken away by the engine with the exhaust gas. In the current situation where resources are increasingly scarce and energy conservation and emission reduction are urgent, if this phenomenon can be reduced, it will be very meaningful for car companies and even the entire industry. In this regard, car companies have taken measures to recycle and reuse this energy, that is, to convert the heat energy that will be dissipated in the air into electrical energy or other forms of energy for storage and utilization, to power the electrical equipment on the car and drive the car.

When it comes to automobile energy recovery, I believe many people first think of brake energy recovery. This is because this method is the most common in real-world applications, especially with the trend of electric vehicles and hybrid vehicles. Due to the energy management system, the brake energy recovery system has basically become a "must-have" for these two types of vehicles. In fact, in addition to this method, car companies and parts manufacturers have also made some other attempts to recover energy to further tap its potential. As mentioned above, the energy they want to recover may come from the kinetic energy of the shock absorber or from the exhaust heat.

This article mainly introduces and shares the brake energy recovery system and two other main automobile energy recovery methods. Welcome to pay attention.

Braking energy recovery

Relevant data show that in urban conditions, the energy consumed by braking accounts for about 50% of the total driving energy. If this part of energy can be recovered, it will produce considerable economic and environmental benefits.

The working principle of the brake energy recovery system is not difficult to understand. Simply put, when the driver releases the accelerator pedal or applies the brakes, the vehicle slows down and generates excess energy. The brake energy recovery system recovers the excess energy and, under the regulation and control of the generator control unit, increases the voltage of the generator, charges the battery system, and recovers and stores the excess energy in the form of electrical energy.

At present, the application of this technology is very common. Suzuki's small concept car Suzuki G70, which will be released at the Geneva Motor Show in March, is equipped with this system, and it is also equipped with a start/stop system. This concept car is not equipped with a hybrid system, but a 0.8T turbocharged gasoline engine. It is understood that thanks to this complete power system, combined with a lightweight body design, the fuel consumption of Suzuki G70 is only 3.76L per 100 kilometers, and the carbon dioxide emissions are 70g/Km. In addition to Suzuki, BMW Brilliance, Mazda, Audi, SAIC Roewe and others have also applied this technology to related models. 　

In this way, such a technology should be put into large-scale application. But the reality is that to achieve better braking energy recovery, not only the software of the energy management system and the engine control system must be specially developed and improved, but also how to ensure the stability of braking, how to effectively store and utilize energy, and how to improve energy recovery efficiency must be solved, which may bring technical and cost challenges. For this reason, the technical routes of different companies are somewhat different, and the actual application results are also mixed.

Suspension energy recovery

When a car is driving on the road, the uneven road surface will cause the car to vibrate. Usually, this part of the vibration mechanical energy is converted into heat energy in the form of friction by the car suspension shock absorber, and finally dissipated into the air. With the increasing requirements for energy saving of automobiles, a feedback suspension that can not only improve the driving smoothness of the car but also recover vibration energy has come into being.

Energy-feeding suspension can be divided into mechanical, electromagnetic and hybrid types according to different structural forms. Taking electromagnetic energy-feeding suspension as an example, it uses a mechanical/electrical conversion device (motor) instead of a traditional damper to convert the relative motion between the wheel and the vehicle body into linear or rotational motion, and then drives the motor to generate electricity, converting the vibration energy of the wheel or vehicle body into electrical energy for storage, which is used for active control of the suspension or to power other electrical equipment.

In terms of practical application, Audi is one of the companies that invested in the development of related products earlier. As early as 2014, there was news that Audi was developing a system for recovering "suspension energy". Consistent with the principle of the energy-feeding suspension mentioned above, the shock absorber will gradually heat up during the driving process of the car, and the heat generated will generally dissipate into the air and be wasted. The new system launched by Audi recovers this energy through a generator. The recovered energy will be stored in the battery pack and used to power the motor in the hybrid vehicle powertrain or the electrical and electrical components of traditional vehicles. This system can reduce the workload of the internal combustion engine and improve fuel economy. This system can also extract energy from the battery to adjust the suspension and achieve different driving experiences.

According to relevant information, this suspension energy recovery system was officially released in the second half of 2015, and relevant reports in 2016 showed that Audi plans to use a shock absorber with electromechanical conversion function (Audi calls it eROT) to replace the traditional suspension system, which should be this system. Audi also said that it can obtain an average of 100-150 watts of energy in road tests in Germany. However, it is understood that this eROT system is still in the prototype stage, and it is uncertain whether and when it will be mass-produced.

It can only be said that if Audi's system can be successfully applied, it will undoubtedly have a positive impact on the entire industry.

Exhaust heat recovery

It is understood that one-third of the energy generated by the vehicle transmission system is lost through the exhaust system in the form of heat energy. Related research reports also show that in the study of the exhaust waste heat recovery system of small-sized gasoline engines using the Rankine cycle, it was found through the analysis of engine exhaust energy that in the main operating conditions, the energy taken away by the exhaust accounts for 25%-40% of the consumed fuel energy, and the exhaust temperature is 500-750℃, which has a high recovery potential. It can be seen from this that the realization of the re-collection and utilization of this heat energy will hopefully achieve a good energy-saving effect.

The IONIQ, a compact model of the Hyundai Group of South Korea, is equipped with an exhaust heat recovery system, which is the first in the world. It is understood that the compact exhaust heat recovery system developed by Faurecia is installed on the new Hyundai IONIQ hybrid and plug-in hybrid vehicles. According to the US Environmental Protection Agency Federal Test Procedure (FTP20) test, it can save nearly 3% of fuel consumption. Faurecia said that this energy recovery system is particularly suitable for hybrid vehicles that will develop rapidly in the future.

According to relevant information, in this system, exhaust heat is recovered through a gas/liquid exchanger integrated in the exhaust line, and nearly 3 kilowatts of energy is delivered to the engine cooling system to heat the engine and cockpit. This allows hybrid vehicles to be in electric mode for a long time, thereby improving fuel economy and reducing carbon dioxide emissions. In addition, automakers can reduce or abandon expensive electronic auxiliary cabin heaters. Once the set cooling temperature is reached, the control valve will be activated to complete the bypass of the system to prevent the engine from overheating.

The company also said that in this system, by warming up the engine faster and increasing the use of electric mode, it will be able to save about 7% of fuel consumption. If this concept comes true, it will undoubtedly be good news for companies that are struggling to cope with increasingly stringent fuel consumption and emission standards.

It is also understood that Hyundai IONIQ Hybrid has recently started selling in the United States, and Hyundai IONIQ pure electric and oil-electric hybrid models will also be officially launched in China in March this year as imported models. In other words, this system is about to undergo preliminary market testing, and we will wait and see what the results will be!

Summary: In fact, there are many places in the car such as brakes, suspension, exhaust, etc. where energy can be recovered. What enterprises need to do is to discover, research and test. Only in this way can they be more confident and have more development potential in the face of increasingly stringent emission and fuel consumption standards. Here, we look forward to more new technologies that adapt to the market in the future!