Hydraulic Hybrid Technology: No "Electric" Lightweight

Hydraulic principles and related technologies are not young in the sequence of human scientific and technological achievements. However, in the current trend of the most fashionable energy-saving automotive research, it has found a top position. Today, many companies around the world are developing hydraulic hybrid transmission systems that can drive heavy vehicles such as buses, and have achieved significant breakthroughs in the past 2011. Hydraulic hybrid technology uses high-pressure liquid instead of current to drive the wheels, which is more cost-effective and more energy-saving and emission-reducing than traditional hybrid technologies. The assessment made by Parker Hannifin Hydraulic Systems, a giant in the world of motion and control, concluded that the increase in fuel economy brought about by hydraulic hybrid technology reached 30% to 70%.

Perhaps in the near future, people will be able to see a "hybrid battery" hybrid car.

Break the ceiling of energy saving ceiling

As a world automobile power country, the US automotive industry has been at the forefront of research on hydraulic hybrid power. The most representative of these is the Altair Industrial Design Company's 2011 launch known as the "world's first hydraulic hybrid bus."

Altair said that hydraulic hybrid technology makes the car's fuel economy twice that of conventional car piston engines. Many large-scale automobiles and logistics companies have developed a strong interest in this. For example, United Parcel Service (UPS) has already begun experimenting with the use of this new hybrid truck to deliver parcels; the Chrysler Group, after testing a hydraulic hybrid minivan, found that this technology allows vehicles to drive on city roads. The fuel economy under the conditions increased by 60%.

In addition to companies, government agencies such as the US Environmental Protection Agency have joined the push for hydraulic hybrid technology. The agency said that the current conventional internal combustion bus needs one gallon of fuel every three miles. With hydraulic hybrid technology, the vehicle's fuel consumption can be reduced by one third.

It is worth mentioning that this effective energy-saving technology waited for years before it was affirmed and valued by the American industry. Altair Industrial Design Company spent a lot of time and energy before this, dedicated to the minibus lightening project of the US Department of Transportation. It was not until 2009 when the US Department of Energy proposed a more fuel-efficient power system that Altair realized that ordinary hybrid electric power systems did not give a satisfactory answer. It not only failed to achieve the goal of higher fuel efficiency, but also failed to meet the required durability, and could not break the "ceiling" of chasing the energy-saving ceiling.

In the end, Altair made the choice of using liquid instead of current.

Mixed with oil and electricity "looks apart"

A hydraulic hybrid system that uses liquid instead of electric current actually follows the same operating principle as a bit of hybrid technology: it recovers the heat energy the vehicle consumes during braking and uses it to drive the vehicle forward. Only the latter is to store energy in the battery as current.

In vehicles using hydraulic hybrid technology, the diesel engine drives the hydraulic pump engine, and the hydraulic pump engine recharges the high voltage battery. The battery drives an inclined-shaft hydraulic pump engine on the rear wheel to drive the vehicle. A low pressure reserve is used to collect the liquid and then send the liquid back to the first hydraulic pump engine, thus forming a complete hydraulic circulation system.

Like electric hybrid engines, hydraulic hybrid engines also have the ability to provide regenerative braking. Cargo delivery vehicles and earth-moving vehicles often brake and brake. When the vehicle brakes, the hydraulic pump engine will charge the high-voltage battery. When the truck is started again, the energy stored in the battery can be used to reduce the load on the diesel engine. This energy can also limit the burst of propulsion when the engine is closed, for example, when maneuvering the vehicle indoors.

"The time for a brake is very short, so that the battery can not store all the energy that can be recovered. The best hybrid vehicle can only recover 25% of the brake energy loss. The hydraulic system can reach 75%." Altair Company Tim Smith, director of engineering design, said.

Of course, in a world where the level of electrification is constantly improving, the hydraulic engine technology looks a bit out of date. However, hydraulic pump engines and batteries provide at least one reliable, low-cost way of applying torque and stored energy, which is what hybrid vehicles are designed to achieve.

In addition, hydraulic engines have a significant power density advantage compared to electric systems. It also has many advantages such as smooth transmission, light weight, small size, large carrying capacity, easy stepless speed regulation, easy to implement overload protection and simplified mechanism.

To quit “臃” or “noise” is more forceful

At present, hydraulic hybrid technology is mostly applied to public transportation and logistics transportation, but this does not mean that it cannot be applied to small vehicles such as cars. Many automakers have begun research into grafting hydraulic hybrid technology onto their products. Artemis Intelligent Power Company conducted experiments on hydraulic hybrid technology in the BMW 5 Series sedan as early as 2009. The results show that the fuel consumption in urban road conditions is reduced by half. Ford also said in early 2011 that the F-150 pickup truck with its hydraulic hybrid system, developed in collaboration with the Compact, High-Efficiency Fluid Power Research Center, has reached an ideal level of 40 miles per gallon.

Of course, the hydraulic hybrid system still faces many obstacles if it wants to successfully land on small passenger vehicles. Too large a volume is one of them. In addition, controlling engine vibration and other noise is also an important challenge. The noise problem may not be apparent on large vehicles. After all, when trucks are transported with tons of garbage or buses are struggling to get from one bus station to the next, people rarely pay attention to the petrol pump and shake it away. The grid rattled. However, it is difficult for car consumers to be able to understand and tolerate it. In addition, the extra weight of petrol pumps, fluids, and hoses on highways can adversely affect the fuel economy.

It is necessary to point out that although the hydraulic hybrid system has many advantages, but it does not mean that it has the upper hand in the competition with hybrid power technology. After all, the electric system has been completely commercialized and it has already reached the second generation, and the hydraulic system is still in the demonstration stage. In the long run, even hydraulic hybrid proponents believe that electric systems will prevail. Dr. Dicko believes that the electric drive system will start to become very common at a certain time. The adoption of such a system due to trade reasons rather than technical reasons will become overwhelming. Dr. Kovachi, vice president of the hydraulic power division of Parker Hanniwell Hydraulic Systems, did not think hydraulic hybrid systems would always be the best choice for heavy trucks. "Super capacitors will be better. At some point, they can provide better price/performance than hydraulic systems," he said. However, as a technology that can save a large amount of fuel without any new technology, hydraulic hybrid power is still one of the most promising energy-saving technologies as long as it maintains the same trend as hybrid power.