**1. Introduction**

The climate for industrial and economic growth is changing as resource scarcity pushes up costs, and enterprises are more closely scrutinized because of changing expectations about their public and social responsibilities. Governments have set tight CO2 emission rules [1] and new exhaust limits have just been implemented, such as Tier Emission Standards. The next known step will be the 2019/2020 Tier V, which is a regulation imposing an ulterior sharp tightening of exhaust limits, especially in terms of particles. Now, there is a four-year time window to prepare engines for the upcoming regulations through solutions for peak power shaving and the downsizing of diesel engines. Electric and hybrid vehicles are a suitable solution for reaching these target environmental requirements; such vehicles have a huge

© 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**1 Introduction** 

realization of the DDH are performed.

Figure 1 illustrates typical examples of NRMMs.

**Abstract** 

potential for application in the non-road mobile machinery (NRMM) industry, with its market in mining, process and goods manufacturing, forest harvesting and construction work. Figure 1 illustrates typical examples of NRMMs. ulterior sharp tightening of exhaust limits, especially in terms of particles. Now, there is a four-year time window to prepare engines for the upcoming regulations through solutions for peak power shaving and the downsizing of diesel engines. Electric and hybrid vehicles are a suitable solution for reaching these target environmental requirements; such vehicles have a huge potential for application in the non-road mobile machinery (NRMM) industry, with its market in mining, process and good manufacturing, forest harvesting and construction works.

Governments have set tight CO2 emission rules [1] and new exhaust limits have just been implemented, such as Tier Emission Standards. The next known step will be the 2019/2020 Tier V, which is a regulation imposing an

**Electric-driven zonal hydraulics in non-road mobile machinery** 

**Tatiana A. Minav, Jani E. Heikkinen, Matti Pietola** 

The goal of this research is to apply direct-driven hydraulics (DDH) to the concept of zonal (i.e., locally and operation-focused) hydraulics, which is an essential step in the hybridization and automation of machines. DDH itself aims to combine the best properties of electric and hydraulic technologies and will lead to increased productivity, minimized energy consumption and higher robust performance in both stationary and mobile machines operating in various environments. In the proposed setup, the speed and position control of a double-acting cylinder is implemented directly with an electric motor drive in a closed-loop system without conventional control valves and an oil tank. The selection of the location of the hydraulic accumulator and connection of the external leakage lines will also be part of this study. Simulations and experimental research to study the details of the hydromechanical and electrical

Figure 1. Examples of non‐road mobile machinery: (a) excavator; (b) mine loader and (c) forest harvester. The NRMM industry and its customers are traditionally quite conservative in putting new ideas and technologies **Figure 1.** Examples of non-road mobile machinery: (a) excavator; (b) mine loader and (c) forest harvester.

into use. When they opt for "mild hybridization", the machine manufacturers do not need to change the construction frame of the whole machine immediately. However, some changes in layout design concepts, machine types and business models should be considered in the long term. Therefore, we address several challenges to improve NRMMs by bringing zonal hydraulics into machines. Combining the best properties of traditional hydraulics and electric intelligence allows the following benefits to be achieved in NRMMs: easy electrification of NRMMs higher efficiency compared to conventional machines electrohydraulic power pack with no tank and pipelines reduction of potential leakage points power-on-demand control The NRMM industry and its customers are traditionally quite conservative in putting new ideas and technologies into use. When they opt for "mild hybridization", the machine manufacturers do not need to change the construction frame of the whole machine immedi‐ ately. However, some changes in layout design concepts, machine types and business models should be considered in the long term. Therefore, we address several challenges to improve NRMMs by bringing zonal hydraulics into machines. Combining the best properties of traditional hydraulics and electric intelligence allows the following benefits to be achieved in NRMMs:

1


### **1.1. State of the art**

During recent years, the NRMM industry has had a tendency towards integrated, compact electrohydraulic systems that deliver powerful, linear movement with either valve- or pumpcontrolled systems. These technological steps are considered important stages towards a solution to commonly identified problems, such as the reduction of CO2 emissions and improved performance, productivity, reliability and controllability [2, 3], as well as good options for forcing a smaller diesel engine to operate within its optimum efficiency area since, in general, the diesel engines of NRMMs operate far from their optimum efficiency range [4]. Restrictive environmental regulations are not the only factor imposing the need for innovation in NRMMs. Today, as the search for natural resources expands to areas previously considered

too remote and environmentally hostile to support viable extraction and processing opera‐ tions, researchers all around the world are facing the challenge of establishing and maintaining industrial activities in extreme environments. In these, components of the drive face thermal issues, primarily at start-up, when everything in the drive has cooled down to low, even Arctic temperatures. Under these conditions, conventional hydraulic fluid in all hydraulic systems solidify, so when the NRMM starts up, there is no fluid circulating to protect the pump and other components from extreme wear. For successful operation, a relevant start-up procedure is crucial, as the risk of equipment failure is unacceptable in remote locations. 22 31- 32 Michel, S., et al. Energy-efficiency and thermo energetic behavior of electrohydraulic compact drives. 9th IFK Conf. 2014. Michel, S., et al. Energy-efficiency and thermo energetic behavior of electrohydraulic compact drives, at 9th International Fluid Power Conference (IFK), 24 - 26 March 2014, Aachen, Germany. 22 1-2 Minav, T., Bonato, C., Sainio, P., Pietola, M. Direct driven hydraulic drive, at IFK, March 2014, Aachen, Germany. Minav, T., Bonato, C., Sainio, P., Pietola, M. Direct driven hydraulic drive, at 9th International Fluid Power Conference (IFK), 24 - 26 March 2014, Aachen, Germany.

potential for application in the non-road mobile machinery (NRMM) industry, with its market in mining, process and goods manufacturing, forest harvesting and construction work. Figure

The climate for industrial and economic growth is changing as resource scarcity pushes up costs, and enterprises are more closely scrutinized because of changing expectations about their public and social responsibilities. Governments have set tight CO2 emission rules [1] and new exhaust limits have just been implemented, such as Tier Emission Standards. The next known step will be the 2019/2020 Tier V, which is a regulation imposing an ulterior sharp tightening of exhaust limits, especially in terms of particles. Now, there is a four-year time window to prepare engines for the upcoming regulations through solutions for peak power shaving and the downsizing of diesel engines. Electric and hybrid vehicles are a suitable solution for reaching these target environmental requirements; such vehicles have a huge potential for application in the non-road mobile machinery (NRMM) industry, with its market in mining, process and good manufacturing, forest harvesting and construction works.

**Electric-driven zonal hydraulics in non-road mobile machinery** 

**Tatiana A. Minav, Jani E. Heikkinen, Matti Pietola** 

The goal of this research is to apply direct-driven hydraulics (DDH) to the concept of zonal (i.e., locally and operation-focused) hydraulics, which is an essential step in the hybridization and automation of machines. DDH itself aims to combine the best properties of electric and hydraulic technologies and will lead to increased productivity, minimized energy consumption and higher robust performance in both stationary and mobile machines operating in various environments. In the proposed setup, the speed and position control of a double-acting cylinder is implemented directly with an electric motor drive in a closed-loop system without conventional control valves and an oil tank. The selection of the location of the hydraulic accumulator and connection of the external leakage lines will also be part of this study. Simulations and experimental research to study the details of the hydromechanical and electrical

1

Figure 2

1 illustrates typical examples of NRMMs.

easy electrification of NRMMs

**•** easy electrification of NRMMs

**•** power-on-demand control

**•** sensorless position control

**1.1. State of the art**

**•** reduction of potential leakage points

NRMMs:

 reduction of potential leakage points power-on-demand control sensorless position control

 higher efficiency compared to conventional machines electrohydraulic power pack with no tank and pipelines

**•** higher efficiency compared to conventional machines

**•** electrohydraulic power pack with no tank and pipelines

Figure 1 illustrates typical examples of NRMMs.

(a) (b) (c)

Figure 1. Examples of non‐road mobile machinery: (a) excavator; (b) mine loader and (c) forest harvester.

**Figure 1.** Examples of non-road mobile machinery: (a) excavator; (b) mine loader and (c) forest harvester.

hydraulics and electric intelligence allows the following benefits to be achieved in NRMMs:

The NRMM industry and its customers are traditionally quite conservative in putting new ideas and technologies into use. When they opt for "mild hybridization", the machine manufacturers do not need to change the construction frame of the whole machine immediately. However, some changes in layout design concepts, machine types and business models should be considered in the long term. Therefore, we address several challenges to improve NRMMs by bringing zonal hydraulics into machines. Combining the best properties of traditional

The NRMM industry and its customers are traditionally quite conservative in putting new ideas and technologies into use. When they opt for "mild hybridization", the machine manufacturers do not need to change the construction frame of the whole machine immedi‐ ately. However, some changes in layout design concepts, machine types and business models should be considered in the long term. Therefore, we address several challenges to improve NRMMs by bringing zonal hydraulics into machines. Combining the best properties of traditional hydraulics and electric intelligence allows the following benefits to be achieved in

During recent years, the NRMM industry has had a tendency towards integrated, compact electrohydraulic systems that deliver powerful, linear movement with either valve- or pumpcontrolled systems. These technological steps are considered important stages towards a solution to commonly identified problems, such as the reduction of CO2 emissions and improved performance, productivity, reliability and controllability [2, 3], as well as good options for forcing a smaller diesel engine to operate within its optimum efficiency area since, in general, the diesel engines of NRMMs operate far from their optimum efficiency range [4]. Restrictive environmental regulations are not the only factor imposing the need for innovation in NRMMs. Today, as the search for natural resources expands to areas previously considered

realization of the DDH are performed.

**Abstract** 

**1 Introduction** 

144 New Applications of Electric Drives

Zonal or decentralized hydraulics—as we will call it—is an approach first introduced in the aircraft industry [5]. Adapting this time-proven design from the aircraft industry, simplifying its design as well as broadening its orientation and performance options will support a similar development in NRMMs. In a fully zonal system, the hydraulic pumps are removed from the engine and replaced within hydraulic power packs distributed throughout the NRMM system. In this architecture, multiple hydraulic power sources may be utilized in each zone in order to achieve energy savings and work with a power-on-demand approach. 23 3-5 Minav, T.A., Bonato, C., Sainio, P., Pietola, M. Efficiency of direct driven hydraulic drive for non-road mobile working machines, at ICEM, September 2014, Berlin, Germany. Minav, T.A., Bonato, C., Sainio, P., Pietola, M. Efficiency of direct driven hydraulic drive for non-road mobile working machines, at 2014 International Conference on Electrical Machines (ICEM), 2-5 September 2014, Berlin, Germany, pp. 2431–2435. Minav, T.A., Bonato, C., Sainio, P., Pietola, M. Efficiency of Remove this reference

Figure 2 illustrates the zonal hydraulic architecture applied to NRMMs. A challenge in this is the increasing number of electric components in the limited volume available in the vehicle. On the other hand, the main advantages of this architecture are the reduced hydraulic tubing (tubes are replaced with wiring), the elimination of some hydraulic components and simplified machine assembly. 23 20- 22 direct driven hydraulic drive for non-road mobile working machines. At 2014 International Conference on Electrical Machines (ICEM), Publication Year: 2014, pp. 2431–2435.

**Figure 2.** Schematics of (a) conventional NRMM, (b) hybrid NRMM with secondary power source DDH with a conven‐ tional tank and (c) DDH without a tank.

In this study, an electrohydraulic actuator (EHA) will be used to achieve high power density, low noise and high performance in a compact package in order to take the development of a power unit onto the next level. The electrohydraulic actuator allows decoupling from the main hydraulic system, thus enabling a zonal approach and, at the same time, reducing parasitic losses in order to obtain better fuel efficiency and lower operating costs. The robust, leak-free,

one-piece housing design delivers system simplicity and lowers both installation and main‐ tenance costs. The electrohydraulic actuator reduces space and weight demands. It can eliminate hoses, fittings, valves and fixtures and is easy to integrate into larger systems.

Currently, electrohydraulic actuators are mostly installed and developed for aircraft applica‐ tions [6, 7], where the price level and reliability requirements are very high. Most of the research studies related to electrohydraulic actuators have been conducted to adjust the state of the servo valve [8, 9]. However, this approach results in low energy efficiency because of the flow via the pressure relief valves of the hydraulic pumps and throttle losses at the control valves. Consequently, several techniques have been developed to overcome this drawback in order to achieve higher efficiency. In ref. [10], the concept of a pump-controlled electrohydraulic actuator is introduced as an advanced hydraulic system where the proposed structure of the electrohydraulic actuator is directly operated by a bidirectional pump. There are already commercially integrated power packages on the market, but they are based on conventional technology and they do not respond to the above-mentioned challenges created by the hybridization problem. Examples of commercial pump-controlled electrohydraulic actuators are, for instance, the mini-motion package from Kayaba Industry Co. [11] and the intelligent hydraulic servo drive-pack from Yuken Kogyo Co. [12]. The disadvantages of the architecture evidenced in ref. [10] are the use of complex and expensive pumps and the lower dynamic properties of the system in general. In addition, none of these commercial solutions are designed for power-on-demand control, sensorless positioning or even energy regeneration, all highly desirable improvements in a competitive product.

Some studies have been conducted to introduce the concept of electrohydraulic actuators as zonal hydraulics in NRMM. In ref. [13], an electrohydraulic actuator is used for the power steering of heavy vehicles. In refs. [14–17], a compact drive for automation of all kinds of linear motions was introduced and investigated from the thermal point of view. In these sources, even if they proposed direct pump control similar to the direct-driven hydraulic approach, a set of valves is used to balance the flow and to ensure the direction of the electrohydraulic actuator motion. In refs. [18, 19], direct-driven hydraulics (DDH), an electrohydraulic actuator, was introduced without conventional directional valves. The DDH drive combines the best properties of electric and hydraulic drive technologies in one:


Therefore, the idea of implementing the DDH drive in the powertrain of NRMMs as an application of the zonal hydraulic concept was born. In this research, direct-driven hydraulics (DDH) is seen as a tool to convert existing NRMMs to hybrids combining the best properties of traditional hydraulics and electric intelligence. Figure 3 illustrates the hybrid proposal for NRMMs. With this approach, several challenges that traditionally manifest themselves in the hybridization process will be solved. In the proposed setup, the speed and position control of a double-acting cylinder is implemented directly with a motor drive in a closed-loop system without conventional control valves and an oil tank. The selection of the optimal size and the location of the hydraulic accumulator will also be part of this study. Simulations and experi‐ mental research to study the details of the hydro-mechanical and electrical realization of the DDH will be performed.

**Figure 3.** Hybrid proposal for NRMM with DDH.

one-piece housing design delivers system simplicity and lowers both installation and main‐ tenance costs. The electrohydraulic actuator reduces space and weight demands. It can eliminate hoses, fittings, valves and fixtures and is easy to integrate into larger systems.

Currently, electrohydraulic actuators are mostly installed and developed for aircraft applica‐ tions [6, 7], where the price level and reliability requirements are very high. Most of the research studies related to electrohydraulic actuators have been conducted to adjust the state of the servo valve [8, 9]. However, this approach results in low energy efficiency because of the flow via the pressure relief valves of the hydraulic pumps and throttle losses at the control valves. Consequently, several techniques have been developed to overcome this drawback in order to achieve higher efficiency. In ref. [10], the concept of a pump-controlled electrohydraulic actuator is introduced as an advanced hydraulic system where the proposed structure of the electrohydraulic actuator is directly operated by a bidirectional pump. There are already commercially integrated power packages on the market, but they are based on conventional technology and they do not respond to the above-mentioned challenges created by the hybridization problem. Examples of commercial pump-controlled electrohydraulic actuators are, for instance, the mini-motion package from Kayaba Industry Co. [11] and the intelligent hydraulic servo drive-pack from Yuken Kogyo Co. [12]. The disadvantages of the architecture evidenced in ref. [10] are the use of complex and expensive pumps and the lower dynamic properties of the system in general. In addition, none of these commercial solutions are designed for power-on-demand control, sensorless positioning or even energy regeneration,

Some studies have been conducted to introduce the concept of electrohydraulic actuators as zonal hydraulics in NRMM. In ref. [13], an electrohydraulic actuator is used for the power steering of heavy vehicles. In refs. [14–17], a compact drive for automation of all kinds of linear motions was introduced and investigated from the thermal point of view. In these sources, even if they proposed direct pump control similar to the direct-driven hydraulic approach, a set of valves is used to balance the flow and to ensure the direction of the electrohydraulic actuator motion. In refs. [18, 19], direct-driven hydraulics (DDH), an electrohydraulic actuator, was introduced without conventional directional valves. The DDH drive combines the best

all highly desirable improvements in a competitive product.

properties of electric and hydraulic drive technologies in one:

**•** the pump units and internal combustion motor are disconnected

**•** no need for expensive variable displacement pumps

and electric batteries

146 New Applications of Electric Drives

**•** direct control of flow, as well as the velocity and position of the actuator

**•** high hydraulic efficiency because there are virtually no flow-restricting valves

compromises) since each actuator has two pump units and an electric motor

**•** easier to find the optimum operational point for each of the powertrain components (fewer

**•** possibility of realizing efficient energy recovery systems using both hydraulic accumulators

Therefore, the idea of implementing the DDH drive in the powertrain of NRMMs as an application of the zonal hydraulic concept was born. In this research, direct-driven hydraulics

The next chapter introduces the experimental DDH setup.
