With the acceleration of automobile electrification, the role of hydraulic system is being paid more attention. In the electrified structure, the battery life is the most important, and the hydraulic system is traditionally an energy consuming technology. Therefore, the improvement of the hydraulic system is the key to make the battery life of electrified vehicles longer. In this case, one can say that the revival of hydraulic technology is in progress, said Brianna Jackson, an industrial research analyst at interact analysis.
So far, automakers have explored various solutions aimed at improving the efficiency of their vehicles. In the hydraulic system, these changes range from the adoption of new technologies to the redesign of the whole system. Through the tests of these new components and systems, it is very clear that improving vehicle efficiency through the hydraulic system will not be a solution suitable for all situations. Factors such as vehicle size, operating conditions, work cycle and the degree of control required for application determine the feasibility of the relevant solutions. As car manufacturers strive to achieve their electrification goals, these factors must be kept in mind when striking a balance between efficiency and practicality.
In this insight, we outline the challenges faced by the traditional hydraulic architecture after the electrification of off-road vehicles, and the advantages and disadvantages of emerging hydraulic technologies in this context.
Why must we change the status quo?
The advantage of traditional hydraulic systems has always been the ability to achieve unmatched power density at an extremely low cost. From the perspective of automobile OEMs, this advantage is so great that the efficiency of the hydraulic system becomes an afterthought. Although automobile OEMs have not rapidly eliminated or even changed this proven technology in their designs, one fact is becoming clear: hydraulic systems will need to greatly improve energy efficiency to adapt to electrification.
Some automobile manufacturers have begun to electrify certain parts of their product portfolios and have made significant progress in evaluating the redesign of hydraulic systems. An example of the beginning of electrification is the electric mini excavator. We estimate that in 2021, the hydraulic system market sold to this type of vehicles will be about $1.6 billion. Given their scale, these vehicles will become fertile test grounds for new hydraulic technologies. The electrification speed of the mini excavator is as follows.
Hydraulic technology -- electrified electromechanical actuator of small excavator
Earlier this year, Bobcat launched their electric small crawler loader - t7x. This electric crawler loader is the result of cooperation with Moog construction company. In addition to its electric power system, one of the most interesting design features of the car is that the ball screw mechanical actuator replaces the hydraulic cylinder. As mentioned above, electromechanical actuators have advantages in maintenance compared with hydraulic actuators. However, the most urgent constraint to replace the hydraulic cylinder is the loss of power density. Although electromechanical actuators provide benefits such as tighter control and less noise in applications requiring less power density. In addition, in an electrified vehicle, removing the hydraulic system can simplify the overall design.
In our recent insight, we outlined the best use cases of replacing hydraulic cylinders with electromechanical actuators. These use cases include vehicles of the material handling department, such as aerial work platforms and long-distance carriers. However, the construction industry may also see more use of electromechanical putters. In the right application, replacing hydraulic drive with electromechanical drive can reduce the total cost of ownership (TCO), because it saves fuel, reduces maintenance costs, and tax subsidies brought by the implementation of green technology.
One step change in efficiency
For many years, digital hydraulic technology has been a hot topic. The name of digital hydraulic technology comes from the fast on-off valve used in this technology. This technology can often bring obvious high efficiency when replacing the traditional hydraulic components. In the past few years, we have seen various digital hydraulic solutions released in the market.
At the end of 2020, Volvo announced to cooperate with norrhedro to produce electric excavators. Norrhedro's patented technology, norrdigi system, has a multi chamber digital hydraulic actuator. This modular system greatly reduces the bill of materials by eliminating the main control valve and shortening the required hose length. The higher efficiency brought by the digital hydraulic system also supports longer battery life, which is the key to making the electric excavator a practical solution.
Another example in the field of digital hydraulics is Danfoss' widely discussed digital displacement pump (DDP). This type of pump has been proven to improve the fuel efficiency of vehicles driven by internal combustion engines by 30%. Although the market's view of DDP is still developing, as the successor of traditional hydraulic technology, this technology has great prospects. Danfoss has consolidated its early position in the field of digital hydraulic.
Digital hydraulic technology provides higher efficiency while maintaining the traditional hydraulic structure to a great extent. For this reason, we believe that this technology has lasting power in the field of mobile hydraulics. By maintaining the traditional architecture, many disadvantages faced by other solutions, such as electromechanical actuators, can be avoided. We expect that with the development of the off-road vehicle market towards electrification, more digital hydraulic technologies will be introduced.
Electro hydraulic drive
Electro hydraulic drive involves that each actuator is driven by its own special pump and motor. This reduces the throttling loss of the valve, and the modular nature of the technology simplifies the maintenance of the machine in many cases. In addition, the separation of the power system from the working function simplifies the design of the motorized machine. An example of an electro-hydraulic actuator is Bucher's Helax system. According to Bucher, the efficiency of this system is significantly higher than that of the traditional drive system. One of the ways to achieve this high efficiency is through the energy recycling process. In the traditional hydraulic system, an accumulator is required, and Helax can regenerate energy into the battery through the electric motor of the drive system.
The main disadvantage of the electro-hydraulic solution is that the initial cost increases, which is several orders of magnitude higher than the traditional hydraulic drive system. However, in terms of long-term total cost of ownership, higher efficiency can greatly reduce total operating costs. For this reason, electro-hydraulic structure, as a means of electrification, continues to gain the interest of many automobile manufacturers.
Last thought
Electrification has undoubtedly shaken the mature mobile hydraulic system market. Although there is no clear way forward, it is clear that there is no one size fits all solution to optimize vehicle efficiency. Various vehicles, applications and requirements in the off road market will continue to challenge mobile hydraulic suppliers. However, this will also provide opportunities for suppliers to innovate as automotive OEMs compete to electrify their fleets.
