Browse Topic: Electrohydraulics
The traditional braking system has been unable to meet the redundant safety requirements of the intelligent vehicle for the braking system. At the same time, under the change of electrification and intelligence, the braking system needs to have the functions of braking boost, braking energy recovery, braking redundancy and so on. Therefore, it is necessary to study the redundant braking boost control of the integrated electro-hydraulic braking system. Based on the brake boost failure problem of the integrated electro-hydraulic brake system, this paper proposes a redundant brake boost control strategy based on the Integrated Brake Control system plus the Redundant Brake Unit configuration, which mainly includes fault diagnosis of Integrated Brake Control brake boost failure, recognition of driver braking intention based on pedal force, pressure control strategy of Integrated Brake Control brake boost and pressure control strategy of Redundant Brake Unit brake boost. The designed control
Compact off-highway machines should be as maneuverable, versatile and energy-efficient as possible. Key to achieving these goals is the electronification of the working hydraulics. New mini excavators, wheel loaders and track loaders from the Eurocomach brand, which is part of the Italian Sampierana Group, demonstrates the improvements that can be gained by utilizing electrohydraulic pump control and software. Sampierana first launched the electronification of its working hydraulics on its six-ton mini excavators. “Our compact construction machines are used for a wide variety of jobs,” said Giuseppe Fabbri, technical manager at Sampierana. “Loading, excavating or digging should be very accurate or quick and productive to perform, as needed, and also support a wide range of tools - from shovels to hammers or mowers.”
This SAE Aerospace Information Report (AIR) includes all missile and launch vehicle actuation systems, including electrohydraulic, electropneumatic, and electromechanical types. The data for many systems are not complete. As more information becomes available, periodic updates will be issued to complete existing data sheets and to add new ones. An index by type of vehicle and by type of actuation system is included. The actual data sheets in the body of the report are organized in alphabetical order.
The basics of electrohydraulic valves are easy to understand — they are electrically operated valves that control how hydraulic fluid is sent to actuators. However, to apply electrohydraulic valves for efficient and effective hydraulic systems, designers must consider several factors. This article will explore seven key design considerations for applying electrohydraulic valves.
Mobile hydraulics expert details key trends in controls and IoT connectivity to improve machine design and end-user operations. Off-highway equipment manufacturers are increasingly working with suppliers of drivetrain systems and electrohydraulic (EH) system suppliers to advance the digitalization of mobile-machine technology. OEMs are completing their own R&D efforts to determine the best ways to use digitalized EH systems, sensors, controls and mobile edge gateway devices. They also are working with end-user customers to clearly define what “actionable data” really means for off-highway operations. What device data, or correlated datasets from multiple devices, provides the most value for end users? This is at the crux of creating the IoT-ready technologies that can advance machine performance. The development of IoT-ready technology needs to respond to the requirements of key uses in both OEM and end-user communities. Their needs are interrelated and based on exploiting the
The four-wheel drive electric sport utility vehicle (SUV) requires high dynamic performance, and the front and rear axles are matched with a high-power motor. High-power motors operate under low-speed and low-torque conditions, with low efficiency and large power loss. To reduce the power loss under low-speed and low-load conditions, a hybrid system of front and rear dual motors and dual hydraulic pumps/motors is designed. A simulation model of a four-wheel drive SUV electrohydraulic hybrid system is constructed. Aiming at the optimal energy consumption, a dynamic programming algorithm is adopted to establish the driving control rules of the vehicle. Constrained by the Economic Commission for Europe Regulation No.13 (ECE R13), a braking-force distribution strategy for the front and rear axles is formulated. On the premise of satisfying the braking safety, regenerative braking is preferred, and the braking energy is recovered to the greatest extent possible. The optimal efficiency curve
A library for modelling faults in multi-domain physical systems is introduced. The library is based on the simulation of fault effects on the system’s behavior. The motivation of how and why to model faults systematically as well as a description of the Modelica®-based library structure with a wizard supporting the semi-automatic augmentation process of faults are outlined. The fault types are classified into continuous and discrete with dedicated type definitions. The application of the Fault library is exemplified in the field of aerospace electrohydraulic actuator. The actuator is equipped with hydromechanical, electrical and digital systems for mitigating failures, which should be tested at an early stage of design. To perform the tests, a multi-domain, dynamic system model is created, wherein failures are systematically simulated using a special approach for fault augmentation. In addition, several complementary tests are obtained by a variants simulation and the simulation
The modular designing principle is generally recognized in the automotive industry. However, the issue of building a wheel open-link locomotion module (OLLM) as a combination of steering (wheel turning), springing, traction drive and braking systems is not properly developed yet. An automated control system (ACS) is needed to able to unite and coordinate all the vehicle systems intended to manage the wheel. The automated control system intended to manage the steering and wheel springing parameters is a combination of an information and power channels, through which the wheel is electro-hydraulically driven, and the steering, springing and braking systems are controlled. The number of such channels in a wheeled mover of the vehicle or mobile robot is defined by the wheel type (driving, driven, steered or non-steered wheel). The plurality of such channels forms a complex of automated control systems of the wheeled mover. This complex is responsible for: 1) Controlling the steering wheel
Camless Variable Valve Actuation (VVA) technologies have been known for improving fuel economy, reducing emissions, and enhancing engine performance. VVA can be divided into electro-magnetic, electro-hydraulic, and electro-pneumatic actuation. A family of camless VVA designs (called LGD-VVA or Gongda-VVA) has been presented in an earlier SAE publication (SAE 2007-01-1295) that consists of a two-spring actuation, a bypass passage, and an electrohydraulic latch-release mechanism. The two-spring pendulum system is used to provide efficient conversion between the moving mass kinetic energy and the spring potential energy for reduced energy consumption and to be more robust to the operational temperature than the conventional electrohydraulic actuation; and the electrohydraulic mechanism is intended for latch-release function, energy compensation and seating velocity control. This paper presents the prototype design of a variable valve-time and two-lift LGD-VVA with bench and engine test
This SAE Aerospace Information Report (AIR) describes a mathematical model that can be used to analyze particle count data. Particle counts that fit the model can be graphically displayed, converted from one counting size-frequency range to another, and extrapolated to estimate counts beyond the measured range. Derivation, applications, and calculations are described.
The scope of this document includes all missile and launch vehicle actuation systems, including electrohydraulic, electropneumatic, and electromechanical types. The data for many systems are not complete. As more information becomes available, periodic updates will be issued to complete existing data sheets and to add new ones. An index by type of vehicle and by type of actuation system is included. The actual data sheets in the body of the report are organized in alphabetical order.
Toyota Motor Corporation has developed a new drivetrain for their flagship Lexus LFA sports car. Passionate driving experience was pursued at the forefront of development. Superior vehicle performance, handling, and responsiveness that seem to anticipate the driver's intentions are achieved. Special vehicle packaging and component placement are adopted in the LFA in order to realize such performance. The engine, clutch, and front counter gear are positioned at the front of the vehicle, and the transaxle at the rear. The engine and transaxle are connected by a rigid torque tube. The transaxle is an automated manual transmission equipped with an electrohydraulic actuator for controlling both the shift and clutch operations. This actuator enables accurate control of the transmission and extremely quick response to shift paddle operation by the driver. This paper describes a general outline of the drivetrain and each component that has significantly contributed to LFA product appeal.
Collaboration between OEMs and suppliers leads to new advances, and challenges, for electrohydraulic system control. Off-highway OEMs have found that electrohydraulics are particularly suited to platforms where there is a high degree of coordination required between the propulsion and work functions, as well as those where functional complexity or repetition of task is more suited to an automated approach. Now, they are turning to the technology to help them meet emerging emissions regulations in the U.S. and Europe. “A major development has been the rapid and increasing demand for hydraulic-hybrid propulsion systems that are highly reliant on electronic controls and software functionality to allow them to deliver better fuel savings, reduce mechanical wear, and improve emissions in conjunction with the mechanical and fluid power subsystem,” said Clyde Thomas, Senior Manager of Technical Services at Eaton.
Recent attention has been given to the energy and fuel economy benefits of replacing hydraulic power steering with electronically controlled electrohydraulic power steering (EHPS) systems for commercial vehicles. Given this emerging capability, investigation of the impact such systems would have on overall large truck stability is reported in this paper. It is found that varying the assist gain associated with the EHPS through the motor drive allows for improved stability of articulated vehicles. This paper first presents a method based on feedback of the rate of change in the articulation angle in conjunction with gain-scheduling to instantaneously vary the assist torque provided by the EHPS system. Experimental results of the design are evaluated through a hardware-in-the-loop (HIL) configuration that confirms the performance benefits of incorporating variable gain steering assist in large trucks.
There is much potential for gain for everyone if OEMs and suppliers work together early in terms of hydraulic system design. Modern off-highway equipment is some of the most powerful, most productive, most impressive machinery ever built. The key to that success is fluid power. It seems, in fact, that the primary function of equipment is to deliver fluid power to the site so that buckets and blades can do their work. As such, it is imperative that OEMs work closely with fluid-power-component manufacturers, no matter how big the OEM, or how vast its knowledge of fluid power.
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