Browse Topic: Hydraulic control

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Pallet/Container Loader Auto-Levelling SystemsARP4776 (Current)9/30/2021
The data in this document is, at this stage, primarily concerned with the interface of pallet/container loaders and lower-deck compartments of standard and wide-body aircraft although the principles illustrated may be applied to the main-decks of narrow and wide-body aircraft. NOTE: For the purpose of this document, in accordance with Part 3 of the Directives for the technical work of ISO and with accepted IATA practice, minimum essential criteria defined by the word "shall" are absolute requirements. Recommended criteria identified by the word "should", while considered important, are not mandatory.
AGE-3 Aircraft Ground Support Equipment Committee
Accurate Pressure Control Based on Driver Braking Intention Identification for a Novel Integrated Braking System2021-01-01004/6/2021
With the development of intelligent and electric vehicles, higher requirements are put forward for the active braking and regenerative braking ability of the braking system. The traditional braking system equipped with vacuum booster has difficulty meeting the demand, therefore it has gradually been replaced by the integrated braking system. In this paper, a novel Integrated Braking System (IBS) is presented, which mainly contains a pedal feel simulator, a permanent magnet synchronous motor (PMSM), a series of transmission mechanisms, and the hydraulic control unit. As an integrative system of mechanics-electronics-hydraulics, the IBS has complex nonlinear characteristics, which challenge the accurate pressure control. Furthermore, it is a completely decoupled braking system, the pedal force doesn’t participate in pressure-building, so it is necessary to precisely identify driver’s braking intention. To improve the control accuracy of the system, this paper proposed a novel pressure control strategy based on driver braking intention identification. Firstly, the structure and working principle of the novel integrated braking system was introduced. Secondly, the driver's braking intention identification strategy was designed. Thirdly, Considering the nonlinear and dynamic characteristics of the system, a cascade closed-loop control strategy including a pressure loop by the feedforward-feedback method, a position loop by the sliding-mode control method, and current loop with friction compensation was proposed. Finally, based on dSPACE products, a hardware-in-the-loop (HiL) experimental bench was built for algorithm verification. The HiL experiment results show that the pressure control strategy has the advantages of accurate response, the braking system pressure follows the driver's expected pressure well.
Zhu, Bing, Zhang, Yihan, Zhao, Jian, Chen, Zhicheng, Jin, Wanli
Coordination Control Strategy for Mode Switching of a Parallel Hybrid Electric System Based on Continuously Variable Transmission02-13-02-00108/11/2020
This study aims to solve the problem of impact in a parallel hybrid electric system based on the continuously variable transmission (CVT) during switching from pure electric mode to engine-driven, power-generating mode. Taking into account the torque response characteristics of the engine and motor and the dynamic characteristics of the wet clutch hydraulic control system, the mode switching process is divided into six stages, namely, pure electric mode, wet-clutch free travel, engine start-up, engine speed synchronization, clutch combination, and engine intervention drive. A coordination control strategy is developed based on the model predictive control algorithm to ensure smooth mode switching. The effectiveness of the control algorithm is verified using Matlab/Simulink and the AMESim co-simulation platform. Results show that with the mode switching coordination control strategy, the components of the system work harmoniously. The maximum impact is reduced by 52.0% at the speed synchronization stage and by 84.3% at the clutch coupling stage compared with the uncoordinated control situation.
Zeng, Xiaohua, Li, Xiaojian, Dong, Bingbing
Hydraulic Directional Control Valves, 3000 psi MaximumJ748_201912 (Current)12/4/2019
This SAE Recommended Practice has been set up by Subcommittee 4 of the Off-Road Machinery Technical Committee and is primarily for directional control valves on construction and industrial machinery equipment as referenced in SAE J1116. The purpose is to establish port area to flow relationship and match valve spool eye ends in relation to rated capacity. Port connections are optional for either the 4-bolt split flange connection or the internal straight thread "O" ring connection.
CTTC C1, Hydraulic Systems
Hydraulic Thermal Bypass ValveTBMG-348758/1/2019
ThermOmegaTech Warminster, PA 877-379-8258
Application of Empirical Asperity Contact Model to High Fidelity Wet Clutch System Simulations2019-01-13014/2/2019
Wet clutches are complex hydrodynamic devices used in both conventional and electrified drivetrain systems. They couple or de-couple powertrain components for applications such as automatic shifting, engine disconnect and torque vectoring. Clutch engagement behaviors vary greatly, depending on design parameters and operating conditions. Because of their direct impact on vehicle drivability and fuel economy, a predictive CAE model is desired for enabling analytical design verification processes. During engagement, a wet clutch transmits torque through viscous shear and asperity contact. A conventional Coulomb’s model, which is routinely utilized in shift simulations, is inadequate to capture non-linear hydrodynamic effects for higher fidelity analysis. Extensive research has been conducted over the years to derive hydrodynamic torque transfer models based on 1D squeeze film or 3D CFD. They are typically coupled with an elastic asperity contact model for mechanical torque transfer. However, the recent advancement reveals no significant asperity deformation at the frictional surface during engagement and establishes a new empirical asperity contact model. This paper describes the integration of the empirical asperity contact model with CFD for developing a high-fidelity wet clutch engagement model. The asperity models are examined in detail for four friction materials to highlight distinct contact behaviors. They are coupled with 3D CFD model in OpenFOAM for engagement simulations, demonstrating the importance of selecting the right asperity model for predictive clutch analysis. A breakdown of hydrodynamic and mechanical torques is provided, enabling numerical examination of clutch engagement processes. Simulation results are compared with clutch module test data that is specifically designed to replicate actual shifting conditions. It is found that accurate simulation of a complete clutch system requires not only engagement physics, but also in-depth understanding of actuator characteristics such as seal drag.
Haria, Hiral, Fujii, Yuji, Pietron, Gregory M., Wang, Pengchuan, Katopodes, Nikolaos, Miyagawa, Masatoshi, Tsuchiya, Takahiro, Nakamura, Shinji, Wendel, Matthew, Miyoshi, Hiroya
FCA debuts new Ram Heavy Duty pickups19AUTP03_163/1/2019
FCA's Ram truck division unveiled its new 2019 Heavy Duty (HD) pickup truck lineup at the 2019 North American International Auto Show (NAIAS). The new HD pickups feature the slick interiors and tech from Ram's new 1500 line, significant powertrain and chassis upgrades and all-new front and rear sheetmetal. The Ram HD lineup will face off against Chevy's new HD pickup offerings and Ford's established F-Series and includes 2500/3500 capacities in regular, crew and mega-cab configurations. Since it's a heavy-duty truck launch, Ram is of course touting new capability figures for its HD lineup, which retains its basic cab architecture, but sees nearly every other part of its chassis upgraded. A new 6.7-liter turbo-diesel producing 1,000 lb·ft of torque-the first HD pickup to break the fourfigure torque-output barrier-combines with a redone frame that's now 98.5% high-strength steel to provide what Ram claims are class-leading figures of 35,100-lb (15,921-kg) towing and 7,680-lb (3,565-kg) of payload.
Seredynski, Paul
Open-Loop Characteristics Analysis and Control of High Speed On-Off Valve2018-01-186810/5/2018
In the process of ABS control, the Anti-lock braking system (ABS) of the vehicle adjusts the wheel cylinder brake pressure through the hydraulic actuator so as to control the movement of the wheel. The high-speed on-off valve (HSV) is the key components of the Anti-lock braking system. HSV affects the performance of the hydraulic actuator and the valve response characteristics affects the Anti-lock braking system pressure response as well as braking effect. In this paper, the electromagnetic field theory and flow field theory of HSV are analyzed, and simulation analysis of electromagnetic field characteristics of HSV is done by ANSYS. Combined with the ANSYS analysis results, a precise physical model of HSV is constructed in AMESim. Meanwhile, the valve response characteristics are analyzed. Moreover, the influence of different wheel cylinder diameter and PWM carrier frequency on hydraulic braking force characteristics are analyzed. The open-loop control methods of hydraulic braking force based on Look-up tables and T-S fuzzy structure are comparatively analyzed. The results show that T-S fuzzy controller can be more direct and rapid training to obtain buck-boost surface without fitting and interpolation of data surface, it is more adaptable. The single-wheel model and ABS sliding mode control module are established in Simulink. The inner ring of the module is hydraulic brake force controller, it is used to control hydraulic braking force precisely. The outer ring of the module is a sliding mode controller to control the wheel slip rate. Based on the above two open-loop control strategies, ABS control can be better achieved to realize anti-lock control of the vehicle in the emergency braking conditions.
Zhuo, Guirong, Shen, Huadong, Xue, Ruonan, Wu, Shenchen
Coordinated Control under Transitional Conditions in Hybrid Braking of Electric Vehicle2018-01-186910/5/2018
In the hybrid brake system of electric vehicle, due to the limitation of the motor braking force when the motor is at high speed and the failure of the regenerative braking force when the motor is at low speed, there are three transitional conditions in hybrid braking: the hydraulic brake system intervenes the braking, the hydraulic brake system withdraws the braking and the regenerative braking force withdraws the braking. Due to the response speed of the hydraulic system is slower than that of the motor, there is a large braking impact (the derivative of braking deceleration) in the transitional conditions of hybrid braking, which deteriorates the smoothness and comfort in braking. Aiming at the impact caused by the poor cooperation between the hydraulic braking force and the motor braking force, a coordinated strategy of double closed-loop feedback and motor force correction is proposed in this paper. The double closed-loop feedback strategy relies on the motor force to compensate the tracking error of hydraulic pressure of the hydraulic brake system. The purpose of the motor force correction strategy is to allow the motor to consistently have the compensation capability under all transitional conditions. Simulation and hardware in-loop test were carried out based on Integrated-electro-hydraulic brake system (I-EHB). The HIL test results show that the proposed strategy can greatly reduce the impact degree when the two kinds of braking force switch. The impact degree of hydraulic braking force intervention decreased from the initial 28.26 m/s3 to 18.39 m/s3, decreased by 34.9%, the impact degree of regenerative braking withdrawal reduced from the initial −60.94 m/s3 to 16.84 m/s3, reduced by 72.3%, which improved the comfort in vehicle braking and provided a reference for the practical application of the strategy.
Yu, Zhuoping, Shi, Biaofei, Xiong, Lu, Han, Wei
Sliding Mode Control of Hydraulic Excavator for Automated Grading Operation02-11-02-00106/7/2018
Although ground grading is one of the most common tasks that hydraulic excavators perform in typical work sites, proper grading is not easy for less-skilled operators as it requires coordinated manipulation of multiple hydraulic cylinders. In order to help alleviate this difficulty, automated grading systems are considered as an effective alternative to manual operations of hydraulic excavators. In this article, a sliding mode controller design is presented for automated grading control of a hydraulic excavator. First, an excavator manipulator model is developed in Simulink by using SimMechanics and SimHydraulics toolboxes. Then, a sliding mode controller is designed to control the manipulator to trace a predefined trajectory for a grading task. For a comparison study, a PI controller is used to control the manipulator to perform a grading task following the same desired trajectory and the performance is compared with those obtained by the sliding mode controller. The simulation results show that the sliding mode controller can control the grading operation with less tracking errors than the PI controller.
Xu, Jiaqi, Yoon, Hwan-Sik
Two-Speed Rotorcraft Research Transmission Power-Loss Associated with the Lubrication and Hydraulic Rotating Feed-Through Design FeatureF-0074-2018-128535/14/2018
ABSTRACT An investigation was completed into the power loss associated with a rotating feed-through (RFT) design feature used to transfer lubrication and a hydraulic control signal from the static reference frame to a rotating reference frame in the NASA GRC two-speed transmission tests conducted in the Variable-Speed Drive Test Rig. The RFT feature, not commercially available, was created specifically for this research project and is integral to all two-speed transmission configurations tested, as well as a variant concept design for a geared variable-speed transmission presented at AHS Forum 71 in 2015. The experimental set-up and results from measurements in the isolated rotating-feed-through (RFT) experiments are presented. Results were used in an overall power loss assessment for a scaled conceptual 1,000 horsepower inline concentric two-speed transmission to support a NASA Revolutionary Vertical Lift Technologies (RVLT) Technical Challenge, demonstrating 50% speed change with less than 2% power loss while maintaining current power-to-weight ratios.
Stevens, Mark, Valco, Mark, LaBerge, Kelsen
A Simulation Model for a Tandem External Gear Pump for Automotive Transmission2018-01-04034/3/2018
This paper describes a simulation approach for the modeling of tandem external gear pumps. A tandem gear pump is the combination of two pumps with a common drive shaft. Such design architecture finds application in certain automotive transmission systems. The model presented in this work is applicable for pumps with both helical and spur gears. The simulation model is built on the HYGESim (HYdraulic GEars machines Simulator) previously developed by the authors for external spur gear units. In this work, the model formulation is properly extended to the capabilities of simulating helical gears. Starting directly from the CAD drawings of the unit, the fluid-dynamic model solves the internal instantaneous tooth space volume pressures and the internal flows following a lumped parameter approach. The simulation tool considers also the radial micro-motion of the gears, which influences the internal leakages and the features of the meshing process. The paper details how these aspects are modeled considering that both drive gears share a common shaft. The paper also presents the comparison of the simulation results with experimental data from tests performed on a physical tandem unit, showing how the model is able to accurately predict the performance of both units.
Ransegnola, Thomas M., Vacca, Andrea, Morselli, Mario Antonio, Kowalski, Andrzej, Muizelaar, Richard
Control Valve Test ProcedureJ747_201711 (Historical)11/27/2017
This SAE Standard applies to hydraulic directional control valves as applied to self-propelled work machines referenced in SAE J1116. It describes a laboratory test procedure for evaluating: a Flow versus pressure drop b Leakage rate c Operating effort d Metering characteristics versus spool travel, pilot pressure, or electrical current e Relief valve characteristics The document applies to single and multiple section hydraulic directional control valves. This document illustrates axial, manually operated valves although the test procedure is applicable to other input forms such as rotary actuation, electric current, hydraulic or pneumatic pressure. Performance characteristics such as metering hysteresis or dynamic response may have a significant effect on some of these tests.
CTTC C1, Hydraulic Systems
Electric versus Hydraulic Flight Controls: Assessing Power Consumption and Waste Heat Using Stochastic System Methods2017-01-20369/19/2017
Of all aircraft power and thermal loads, flight controls can be the most challenging to quantify because they are highly variable. Unlike constant or impulsive loads, actuator power demands more closely resemble random processes. Some inherent nonlinearities complicate this even further. Actuation power consumption and waste heat generation are both sensitive to input history. But control activity varies considerably with mission segment, turbulence and vehicle state. Flight control is a major power consumer at times, so quantifying power demand and waste heat is important for sizing power and thermal management system components. However, many designers sidestep the stochastic aspects of the problem initially, leading to overly conservative system sizing. The overdesign becomes apparent only after detailed flight simulations become available. These considerations are particularly relevant in trade studies comparing electric versus hydraulic actuation. These two actuation types use power in fundamentally different ways. This paper provides methods to quantify power consumption and waste heat, by applying stochastic system methods. Both electric (electromechanical and electrohydrostatic) and conventional hydraulic actuation are discussed. Formulas are derived to quantify average and peak power demand. A complete set of waste heat mechanisms is also discussed, and methods are provided to quantify each one. For electric actuation, a method is provided to estimate regenerative power. Approximate methods are also addressed, to facilitate quick engineering estimates. In addition, the physical locations of waste heat generation are identified because these can impact thermal management system architecture.
Schley, William
Hydraulic Control of Integrated Electronic Hydraulic Brake System Based on LuGre Friction Model2017-01-25139/17/2017
In this paper, an integrated electronic hydraulic brake(I-EHB) system is introduced, which is mainly composed of a motor, a worm gear, a worm, a gear, a rack etc. The friction leads the system to the creeping phenomenon and the dead zone. These phenomenon seriously affect the response speed and the hydraulic pressure control .In order to realize the accurate hydraulic pressure control of I-EHB system, a new friction compensation control method is proposed based on LuGre dynamic friction model. And the theoretical design of adaptive control method is designed based on the feedback of the master cylinder pressure and the operating state of the system. Then the stability of the control method is proved by Lyapunov theorem. A co-simulation model is built with Matlab/Simulink and AMESim, so as to prove the validity of the control method. Related experiments are carried out to track the different target signals, which is step signal, (different amplitude and frequency) sine wave signal and Artemis signal. Compared with the test result with PID control method or compensation control method based on static friction model, this method based on LuGre dynamic friction model has a definite improvement, which has advantages in dynamic control error. The maximum dynamic control error at low frequency with this method is less than 1 bar and the RMS of error is about 0.2 bar. Therefore this method is an effective way to control the I-EHB system.
Li, Haocheng, Yu, Zhuoping, Xiong, Lu, Han, Wei
Hydraulic Pressure Control and Parameter Optimization of Integrated Electro-Hydraulic Brake System2017-01-25169/17/2017
A general principle scheme of IEHB (Integrated Electro-Hydraulic Brake system) is proposed, and the working principle of the system is simply introduced in this paper. Considering the structure characteristics of the hydraulic control unit of the system, a kind of time-sharing control strategy is adopted to realize the purpose of independent and precise hydraulic pressure regulation of each wheel brake cylinder in various brake conditions of a vehicle. Because of the strong nonlinear and time varying characteristics of the dynamic brake pressure regulation processes of IEHB, its comprehensive brake performance is mainly affected by temperature, humidity, load change, the structure and control parameters of IEHB, and so on. Under certain temperature, humidity and load conditions, whether the matching of the structure and the control parameters of IEHB is appropriate or not, the brake performance of a vehicle would be affected directly and severely, and then the safe driving of a vehicle could not be guaranteed effectively. In order to enhance the adaptability of the pressure regulating performance of IEHB to external influence factors and improve the comprehensive performance index of IEHB, using the software and hardware test platform of IEHB, combining the robustness optimization design method based on the application of GA (Genetic Algorithm) and modern generalized experiments, the structure and the control parameters of IEHB are matched and optimized. Finally, by comparing the results before and after optimization, it is verified that the pressure regulation of optimized IEHB is more rapid, more accurate and more robust, the comprehensive brake performance is significantly improved, and the new type of brake system could well meet the application requirements of an advanced vehicle chassis control system in the future.
Yang, Xiong, Li, Jing, Miao, Hui, Shi, Zheng Tang
Classification and Nomenclature Towing Winch for Skidders and Crawler TractorsJ1014_201708 (Historical)8/7/2017
This SAE Standard includes only those towing winches commonly used on skidders and crawler tractors. These winches are used on self-propelled machines described in SAE J1057, J1116, and J1209. Specifically excluded are those winches used for hoisting operations.
MTC4, Forestry and Logging Equipment
Research on Vehicle Stability Control Strategy Based on Integrated-Electro-Hydraulic Brake System2017-01-15653/28/2017
A vehicle dynamics stability control system based on integrated-electro-hydraulic brake (I-EHB) system with hierarchical control architecture and nonlinear control method is designed to improve the vehicle dynamics stability under extreme conditions in this paper. The I-EHB system is a novel brake-by-wire system, and is suitable to the development demands of intelligent vehicle technology and new energy vehicle technology. Four inlet valves and four outlet valves are added to the layout of a conventional four-channel hydraulic control unit. A permanent-magnet synchronous motor (PMSM) provides a stabilized high-pressure source in the master cylinder, and the four-channel hydraulic control unit ensures that the pressures in each wheel cylinder can be modulated separately at a high precision. Besides, the functions of Anti-lock Braking System, Traction Control System and Regenerative Braking System, Autonomous Emergency Braking can be integrated in this brake-by-wire system. A sliding mode variable structure vehicle dynamics stability controller based on hierarchical control framework is built in MATLAB/Simulink. The I-EHB actuator model and vehicle dynamic model with 15 degrees of freedom are built in simulation package AMESim through a parameterized and modularized method. Simulations are conducted via co-simulation platform using MATLAB/Simulink and AMESim under scenarios of the typical braking and NHTSA FMVSS 126 standard-Sine With Dwell. Simulation results show that hydraulic braking forces are coordinated well during typical braking process, verifying the feasibility and effectiveness of the models built and the control strategy proposed. Under Sine With Dwell maneuver, compared with the base systems equipped without/with the conventional ESP, the proposed stability control system has a good improvement on the vehicle dynamics.
He, Xiangkun, Yang, Kaiming, Ji, Xuewu, Liu, Yahui, Deng, Weiwen
Anti-Lock Braking System Control Design on An Integrated-Electro-Hydraulic Braking System2017-01-15783/28/2017
Two control strategies, safety preferred control and master cylinder oscillation control, were designed for anti-lock braking on a novel integrated-electro-hydraulic braking system (I-EHB) which has only four solenoid valves in its innovative hydraulic control unit (HCU) instead of eight in a traditional one. The main idea of safety preferred control is to reduce the hydraulic pressure provided by the motor in the master cylinder whenever a wheel tends to be locking even if some of the other wheels may need more braking torque. In contrast, regarding master cylinder oscillation control, a sinusoidal signal is given to the motor making the hydraulic pressure in the master cylinder oscillate in certain frequency and amplitude. Hardware-in-the-loop simulations were conducted to verify the effectiveness of the two control strategies mentioned above and to evaluate them. The simulation platform consists of the I-EHB hardware and software including CarSim and MATLAB/Simulink as well as LabVIEW serving as the communication tool. Conclusions can be reached in the light of testing results that both control strategies were able to achieve anti-lock braking under emergency situations. Compared with safety preferred control, master cylinder oscillation control performed better on the functionality of avoiding braking lock and the reduction of braking distance. Also, it is capable of working with electronic stability control systems (ESC) while safety preferred control cannot.
Liu, Tianyang, Yu, Zhuoping, Xiong, Lu, HAN, Wei
Development of Advanced Braking System for Hybrid Sports Cars2016-01-19239/18/2016
An advanced braking system had to be developed for a next-generation hybrid sports car with Sport Hybrid Super Handling All-Wheel Drive to achieve an intuitive brake feeling in a variety of driving conditions, ultimate track performance and reduction of CO2 emissions per vehicle. This paper outlines the integration of brake-by-wire with traditional high-performance braking hardware and describes the technology needed to achieve these goals. Key focus areas to generate these results were: brake feeling control, corner hardware specification considerations and brake cooling.
Dyar, Lorne R., Akita, Yuichiro, Paul, Scott, Lepito, Joseph, Ishikawa, Yoshio, Watanabe, Tomohiro
Development of New Electronically Controlled Hydraulic Unit for Various Applications2016-01-16604/5/2016
The use of hybrid, fuel cell electric, and pure electric vehicles is on the increase as part of measures to help reduce exhaust gas emissions and to help resolve energy issues. These vehicles use regenerative-friction brake coordination technology, which requires a braking system that can accurately control the hydraulic brakes in response to small changes in regenerative braking. At the same time, the spread of collision avoidance support technology is progressing at a rapid pace along with a growing awareness of vehicle safety. This technology requires braking systems that can apply a large braking force in a short time. Although brake systems that have both accurate hydraulic control and large braking force have been developed in the past, simplification is required to promote further adoption. This paper describes the following three items: (1) an examination of the brake system functions that realize the regenerative-friction brake coordination and collision avoidance support functions, (2) considerations and a proposal for a brake system that achieves the functions described in item (1) with a simple structure, and (3) development of core technology for controlling the wheel cylinder pressure in a brake system equipped with a hydraulic regulator.
Okano, Takahiro, Sakai, Akira, Kamiya, Yusuke, Masuda, Yoshio, Yamaguchi, Tomoyuki
Hydraulic Control of Integrated Electronic Hydraulic Brake System based on Command Feed-Forward2016-01-16584/5/2016
With the development of vehicle electrification, electronic hydraulic brake system is gradually applied. Many companies have introduced products related to integrated electronic hydraulic brake system (I-EHB). In this paper, an I-EHB system is introduced, which uses the motor to drive the reduction mechanism as a power source for braking. The reduction mechanism is composed of a turbine, a worm, a gear and a rack. A control method based on command feed-forward is proposed to improve the hydraulic pressure control of I-EHB. Based on previous research, we simplify the system to first order system, and the theoretical design of the command feed-forward compensator is carried out. The feed-forward controller is applied, including the velocity feed-forward and the acceleration feed-forward, to improve the response speed and tracking effect of the system. Then, related experiments were carried out on test bench to track three different types of target signal (different amplitude and frequency), step signal, sine wave signal and triangular wave signal. Compared with the test result of PID control method, the proposed method has the advantages of fast response and short regulation time. And the Control error at low frequency of the method is about 2 bar - reduced by 56% compared with PID control. Therefore, this method can effectively control the Hydraulic pressure of integrated electronic hydraulic brake system.
Huang, Jie, Xiong, Lu, Xu, Songyun, Yu, Zhuoping
PUMPING UP hydraulic capabilities15OFHP12_0212/1/2015
Electrohydraulic advances keep coming as distributed electronics flex their muscle. Hydraulic technologies are evolving rapidly as clever engineers figure out how to alter spools and valves. These mechanical changes pale in comparison to the advances that transpire as design teams leverage rising computing power and falling prices for electronics. Electrohydraulic systems are employing more sensors and utilizing controls that are networked to a growing number of components. That's making it possible for design teams to continue to improve performance while adding more sophisticated features and functions. These trends show no signs of slowing down.
Costlow, Terry
Study on the Algorithm of Active Pressurization Control of Regenerative Braking System in Pure Electric Vehicle2015-01-27089/27/2015
During the vehicle braking, the Regenerative braking system (RBS) transforms the kinetic energy into electric power, storing it in the power sources. To secure the baking process, it is required to use hydraulic braking pressure to coordinately compensate the regenerative braking pressure. The traditional hydraulic pressure control algorithm which is used in regenerative braking system coordinated control has obvious laddering effect in braking. Unit control cycle pressure deviations seriously affect the comfort and the braking feeling on the vehicle. In order to ensure the accurate implementation of the brake pressure on the wheel cylinder, according to the hardware configuration of regenerative braking system, this paper analyzes the active pressurization state of RBS during braking, acquires the overflow characteristics of the switch valve in ESP hydraulic control unit by designing of high frequency characteristic test experiment, the control range of valve core displacement in the state of inlet valve differential pressure balanced and the relationship between pressure growing rate and inlet valve control duty ratio under the different states of wheel cylinder pressure. On this basis, this paper finishes the development of algorithm of active pressurization control, building the hardware-in-loop testing platform. The test result shows that the actual wheel cylinder pressure can follow the aiming wheel cylinder well, the differential of wheel cylinder can be controlled in the range from −5Bar to 5Bar, the whole pressurization rate follows well compared with traditional control algorithm, justifies the feasibility of the active pressurization control algorithm through the virtual cycle.
Yang, Yi, Chu, Liang, Yao, Liang, Guo, Chong
Linear Control Performance Improvement of High Speed On-Off Valve Controlled by PWM2015-01-26729/27/2015
High speed on-off valve is applied widely in vehicle control systems. When high speed on-off valve is controlled by Pulse Width Modulation (PWM) of high frequency, the valve core can float at a certain position which is adjusted by changing the duty ratio within a certain effective range. Then the high speed on-off valve can control the flow and pressure linearly like proportional valve. Thus it is essential to extend the effective range of duty ratio to improve the linear control performance of high speed on-off valve. In this paper, the high speed on-off valve of the automotive Electronic Stability Program (ESP) is the focus, and its flow force is analyzed in detail to get the effects of hydraulic parameters on the valve performance. The mathematic model of the high speed on-off valve is derived. Then the valve structural parameters are optimized according to the Genetic Algorithm(GA), offering the theoretical references for extending the effective duty ratio of PWM. Besides, the simulation model of high speed on-off valve is established in MATLAB/Simulink, and then embedded in the Hydraulic Control Unit (HCU) simulation model established in AMESim, resulting in the co-simulation model of hydraulic actuator. Finally the simulation model is verified by the hardware-in-loop tests. Based on theoretical analysis, simulations and tests, it is critical to increase the range of flow force for extending the effective range of duty ratio. The pressure difference, the valve seat angle and the throttle diameter of the high speed on-off valve have great effects on the flow force. At last the effects of structural parameters of the high speed on-off valve on extending the range of the linear control are proposed, serving as references for improving the linear control performance of high speed on-off valve.
Meng, Aihong, Song, Jian
Design and Optimization of Clutch Hydraulic Shift Control System in Automatic Transmissions with Failure Protection Function2015-01-02304/14/2015
As a significant control component of vehicles, automatic transmissions should have failure protection function. The failure protection function partly is determined by the hydraulic control system. However traditional design could not cover all of failures, and there is no general design method. A design method is proposed for designing the shift control oil circuit of the hydraulic control system with the failure protection function. The design method is applied to optimize the hydraulic control system of a six-speed automatic transmission. The function of the optimized hydraulic control system is confirmed by the dynamic simulation. The results show that the design method can simplify the hydraulic control system without losing any original functions. The proposed design method is proved to be suitable for all kinds of hydraulic control systems of automatic transmissions.
Tang, Shuhan, Liu, Yanfang, Han, Xiao
Antilock Brake Control System for Four-Wheel-Drive Electric Vehicle with Electro-hydraulic Braking based on Precise Control of Hydraulic Braking Force2015-01-15734/14/2015
With the objective to regulate hydraulic pressure accurately by controlling high speed on-off valve (HSV), finite element models are parameterized based on measured parameters of an ABS hydraulic actuator unit (HCU). The data that reflects transient electromagnetic characteristics of HSV is selected with finite element numerical simulation. Taking full advantage of those data, accurate physical models of HSV are built with other parts of hydraulic braking system. Then a new system structure is proposed to control hydraulic pressure. Not only do simulation results show ideal control effect, but also hydraulic braking system can be controlled under arbitrary input signal. Accordingly, hydraulic braking force can achieve fine regulation. Finally, the hydraulic braking system is utilized to design antilock brake control system for four-wheel-drive electric vehicle with electro-hydraulic braking. That kind of system is established on the basis of hierarchical control structure. By what is called a frequency assignment approach, the lower controller coordinates the total braking torque, which is calculated by sliding mode control algorithm in the upper controller. During braking force distribution, motors execute the higher frequency torque commands, while hydraulic system responses for the lower frequency ones. System's effectiveness is validated under emergent braking based on AMESim-Simulink co-simulation.
Zhuo, Guirong, Shen, Hui, Wu, Shenchen, Ren, Yilin
Hydraulic Directional Control Valves, 3000 PSI MaximumJ748_201410 (Historical)10/24/2014
This SAE Recommended Practice has been set up by Subcommittee 4 of the Off-Road Machinery Technical Committee and is primarily for directional control valves on construction and industrial machinery equipment as referenced in SAE J1116. The purpose is to establish port area to flow relationship and match valve spool eye ends in relation to rated capacity. Port connections are optional for either the 4-bolt split flange connection or the internal straight thread "O" ring connection.
CTTC C1, Hydraulic Systems
Long-Term Storage of Missile Hydraulic SystemsAIR974B (Current)10/4/2013
Much of the available long-term storage test data has been reviewed and topically separated to enable the independent discussion of storage effects on fluids, seals, hydraulic components, and hydraulic systems. Comments are made in Section 4 concerning the applicability of the test results and regarding design practices for storability. Conclusions are drawn in Section 5 regarding inactive storage of hydraulic systems for at least a 7 year period.
A-6A2 Military Aircraft Committee
Ship Systems and Equipment - Selection of Hydraulic Directional Control ValvesJ1783_201305 (Current)5/31/2013
This SAE Recommended Practice provides the designer with guidance for the selection of directional control valves for use in the hydraulic systems of surface ships and submersibles. This guidance includes use of standard valves and interfaces, minimum envelopes that should be reserved to permit interchangeability, environmental considerations, and general technical requirements.
Ship Fluid Systems Committee
Double Tube Shock Absorber Model for Noise and Vibration Analysis2013-01-19125/13/2013
The “structure-borne” noise of the shock absorber is often responsible for undesirable noise in the car interior cabin. These vibrations are attributed to friction, opening/closing of the valves, fluid cavitation or other complex phenomena. Early numerical prediction of the level of these vibrations in the car development process saves time and money. Most of the shock absorber models existing in the literature are limited to analysis of vehicle ride and handling. For noise and vibration analysis, the published works do not explicitly describe any model with its associated assumptions and a clear correlation with the experiments for high frequencies. Moreover there is no interpretation of the physical meaning of the high-frequency content of the response. The objective of the present work is to build a double tube shock absorber model correlated up to 700 Hz. Experimental testing results are presented in this paper in order to put in evidence the non-linear phenomena localized on the piston shock absorber. The model includes the fluid compressible behavior, non-linear flow-rate pressure relationship and spring valve dynamics. Unknown parameters like bulk modulus are identified with experimental data. The numerical results are compared to the experiments, showing that the shock absorber model is able to reproduce very well the local non-linear phenomena. This confirms our hypothesis and improves our knowledge of the potential noise sources in the shock absorber.
Benaziz, Marouane, Nacivet, Samuel, Deak, Jérémie, Thouverez, Fabrice
The World's First Transverse 8-Speed Automatic Transmission2013-01-12744/8/2013
We have developed the world's first 8-speed automatic transmission for transverse FWD/4WD vehicles. The aim of this new automatic transmission was to achieve world-class fuel economy while offering both smooth gear shift and sporty shift feeling suitable for luxury cars. This has been accomplished using wide spread gear ratio, outstanding low drag components and highly efficient hydraulic control system. In addition, we have achieved the compactness similar to current 6-speed automatic transmission by adopting new gear train and compact clutch layout. In this paper, the detail of this automatic transmission is introduced.
Aoki, Toshihiko, Kato, Hiroshi, Kato, Naoki, Masaru, Morise
A Computational Method for Efficient Hub Offset Comparisons with Deflected-Disc Dampers2013-01-13574/8/2013
With deflected-disc dampers, digressive force-velocity shapes are achieved via the combined effects of disc stack stiffness and hub-offset. The degree of digressiveness can be adjusted to alter vehicle performance by changing the proportion of these parameters. Optimizing this relationship can yield substantial vehicle performance improvements, but the time consuming iterative process of developing a new disc stack for each hub-offset discourages experimentation. To enable more efficient digressiveness comparisons, a regression-based computational method has been developed which converts disc stack stiffness from one hub-offset to other offsets directly, without iteration. Once an initial disc stack for one offset has been tuned by traditional methods, stacks for other offsets can be calculated that maintain overall damper control. This paper will present background information on deflected disc valving and curve shaping, describe development of the computational method, and show an example of a typical comparison, graphically.
Cwycyshyn, W. Bradley, Fedullo, Joseph
8000 psi Hydraulic Systems: Experience and Test ResultsAIR4002A (Current)11/15/2012
Shortly after World War II, as aircraft became more sophisticated and power-assist, flight-control functions became a requirement, hydraulic system operating pressures rose from the 1000 psi level to the 3000 psi level found on most aircraft today. Since then, 4000 psi systems have been developed for the U.S. Air Force XB-70 and B-1 bombers and a number of European aircraft including the tornado multirole combat aircraft and the Concorde supersonic transport. The V-22 Osprey incorporates a 5000 psi hydraulic system. The power levels of military aircraft hydraulic systems have continued to rise. This is primarily due to higher aerodynamic loading, combined with the increased hydraulic functions and operations of each new aircraft. At the same time, aircraft structures and wings have been getting smaller and thinner as mission requirements expand. Thus, internal physical space available for plumbing and components continues to decrease.
A-6A2 Military Aircraft Committee
AEROSPACE HYDRAULIC AND PNEUMATIC SPECIFICATIONS AND STANDARDSAIR737D (Historical)8/10/2011
This report lists military and industry specifications and standards which are used in aerospace hydraulic and pneumatic systems. It is intended as a supplement to specifications MIL-H-5440 and MIL-P-5518. Only those hardware standards which have been specifically designed for hydraulic or pneumatic use are listed. Revisions and amendments which are current for these specifications and standards are not listed. Order of procedure for the selection of specifications and standards is covered by MIL-STD-970.
A-6 Aerospace Actuation, Control and Fluid Power Systems
Automatic Transmission Hydraulic Control Systems - TerminologyJ648_201106 (Current)6/13/2011
The following is a list of the most common terminology used in describing hydraulic control systems. The hydraulic control system of an automatic transmission may include oil pumps, pressure regulator, governor, and control valves.
SAE IC Powertrain Steering Committee
Development of iQ with CVT for USA2011-01-14254/12/2011
TOYOTA has developed the iQ with a 1.3L engine for the Scion brand in USA. Due to the importance of fun-to-drive factor for the Scion brand image, a responsive driving performance is required even with compact packaging and a small engine. In addition, because of the recent attention to global-warming and energy issues on a global scale, development of vehicles with high fuel economy is one of the most important issues for a car manufacturer. Therefore, it is necessary for a vehicle to have both high driving performance and fuel economy. TOYOTA has adopted the CVT-i as the transmission for this purpose. The following were achieved by adopting the CVT-i as the transmission for the iQ(1.3L). 1 Responsive driving performance with shift changes without a time lag. 2 Compact transmission for efficient vehicle packaging 3 Class-leading fuel economy performance. Moreover, it was developed with adjustments for the US market by improving the shift schedule for a linear acceleration feel. This paper describes the main structural elements of the transmission and the control system technology for fuel economy and driving performance.
Kamijo, Satoshi, Tomomatsu, Hideo, Sawada, Makoto, Shimazu, Takuro
Use of Dynamic Distortion to Predict and Alleviate Loss of ControlTBMG-91622/1/2011
This research has developed and evaluated the specific concepts, termed “Smart-Cue” and “Smart-Gain,” to alleviate aircraft loss of control that results from unfavorable pilot/vehicle system interactions, including pilot-induced oscillations (PIOs). Unfavorable pilot/ vehicle-system interactions have long been an aviation safety problem. While the effective aircraft dynamic properties involved in these events have been extensively studied and understood, similar scrutiny has not been paid to the many aspects of the primary manual control system that converts the pilot control inputs to motions of the control surfaces. The purpose of the Smart-Cue and Smart-Gain developments is to redress this neglect, and to develop and validate remedial manual control systems.
Electro-Hydraulic Motion Controller for Earthquake SimulationTBMG-106866/1/2010
How do you test the behavior of different soil structures in an earthquake? Obviously, large earthquakes don’t happen often, and they certainly don’t happen on cue. The solution, of course, is to model earthquakes in a laboratory environment. And that’s exactly what is being done by the Center for Geotechnical Modeling at the University of California, Davis. Since it’s not economical to simulate the forces of an earthquake on fullsize soil structures such as one would find beneath a real bridge or large building, physical models of much smaller size are used. In Figure 1, for example, is a model of the San Francisco Bay Area Rapid Transit transbay tube that was recently tested in Davis1.
Aircraft Level Steering Runaway Failure Analysis2009-01-313611/10/2009
Integration of aircraft landing gear systems requires a high level of knowledge and understanding of these systems and how they contribute to aircraft performance. This paper considers a specific design requirement for the steering system. Failure of the steering system, resulting in the aircraft leaving the runway at high speed, can be considered hazardous or even catastrophic. The ability of the system to detect such a failure and take appropriate action is a key aspect of the design. This paper describes an aircraft level steering runaway failure analysis using an aircraft level mechanical and hydraulic control coupled simulation model. The aircraft level simulation model includes aircraft structure, weight and inertia. Appropriate loads and forces (engine thrust, aerodynamic forces, lift, drag) and moments are then applied. The model also includes nose and main landing gears, brakes and tires. The steering system model includes all hydraulic and control components, with failure triggers and steering failure detection logic. The aircraft level steering runaway failure analysis is carried out under different aircraft operations (taxi speeds, weights) in order to identify the most severe condition. In this model, differential braking is applied to simulate a pilot corrective action after the failure is detected. The analysis results show that the aircraft level steering model is able to determine the aircraft landing gear deviation from the runway centerline under failure conditions, with and without pilot corrective actions, and to assess the pilot reaction time required to bring the aircraft back to its runway centerline after the failure occurs. This analysis can be performed during early design stage to evaluate steering system sizing and other performance characteristics and the particular dynamic characteristics of the steering controller. This paper is addressed to the landing gear system performance specialists, who analyze similar conditions, to allow comparison of methods and results.
Wang, Phillip, Dacko, Les, Keller, Nicolas, Wu, Jiangning
Hydraulic Fluid Efficiency Studies in Low-Speed High-Torque Motors2009-01-284810/6/2009
This paper presents an investigation of the fluid viscosity properties that affect the Low-Speed High-Torque (LSHT) efficiency of hydraulic motors. Low speed torque efficiency is important because it often determines the minimum displacement (size) and operating pressure of mobile hydraulic equipment. The viscosity, viscosity index, high-shear viscosity, piezoviscosity and shear stability of prototype fluids have been characterized. These hydraulic fluids have been evaluated in a full-scale hydraulic motor dynamometer. Geroler, axial piston and radial piston motors have been evaluated. Low-speed (1 RPM) testing has been performed under constant pressure conditions in accordance with the ISO 4392-1 standard test method. Startability testing has been performed under constant load conditions in accordance with ISO 4392-2. In startability and 1 RPM testing, the axial piston motor exhibited a 6 percent efficiency gain with a high viscosity index hydraulic fluid. The radial piston and geroler motors showed less of an improvement. The results of this investigation reveal that high VI fluids increase the torque output of axial piston motors under startup and LSHT conditions.
Michael, Paul, Burgess, Kelly, Kimball, Aaron, Wanke, Tom
Fuel Filter Test MethodsJ905_200909 (Current)9/28/2009
The purpose of this fuel filter test method is to provide standardized methods for evaluating the performance characteristics of fuel filters by bench test methods. This, combined with data obtained from application tests, may be used to establish standards of performance for filters when tested by these standard methods. Many variations in requirements of filtration to protect fuel supply equipment on engines and variations in operating conditions make it difficult to specify meaningful "in-service" performance standards by which a filter may be judged. By the use of these standard test methods, test conditions are always the same, and comparisons of the laboratory performance of filters may be made with a high degree of confidence. Once the requirements of a particular application are known, performance standards for suitable filters may be established by these test methods, and adequacy of performance of filters for the job may be determined. In order to achieve the highest degree of reliability of test results, the procedures and equipment must conform to those specified in this code. No minimum performance requirements for filters have been specified, since these are the responsibility of the user and manufacturer. Only the methods of determining, interpreting, and reporting performance characteristics are the proper province of this SAE Standard. Separate chapters cover the test methods necessary to evaluate the several functional capabilities and mechanical properties of the filter. Each chapter is complete with recommended materials, apparatus, and procedures for testing and evaluation. The chapters are: a Chapter 1—Resistance to Flow (Section 3) b Chapter 2—Filter Capacity and Contaminant Removal Characteristics (Section 4) c Chapter 3—Media Migration Test (Section 5) d Chapter 4—Collapse Test (Section 6) e Chapter 5—Ability to Meet Environmental Conditions (Section 7) f Chapter 6—Installation and Removal (Section 8) g Chapter 7—Mechanical Tests (Section 9) h Chapter 8—Material Compatibility (Section 10) To simplify the chapters covering test methods, information of importance but not directly involved in test methods is covered in appendices as follows: a Methods for Sample Analysis (Appendix A)
Filter Test Methods Standards Committee
Classification and Nomenclature Towing Winch for Skidders and Crawler TractorsJ1014_200909 (Historical)9/17/2009
This SAE Standard includes only those towing winches commonly used on skidders and crawler tractors. These winches are used on self-propelled machines described in SAE J1057, J1116, and J1209. Specifically excluded are those winches used for hoisting operations.
MTC4, Forestry and Logging Equipment
Seeing virtually everythingAEROMAY09_035/1/2009
Simulating larger systems helps engineers understand more interactions. Aircraft designs continue to become more complex as electronics, mechanics, and hydraulics merge to provide more precision and efficiency. Design tools help ensure that these complicated designs get to market on time with a minimum of faults, leveraging parallel computing to simulate larger sections of a plane. Software developers are improving the connections between the many tools used to design the complex systems that make up an aircraft. These improved communications play a critical role during the simulation phase when systems or even an entire plane are run through a battery of virtual tests.
Costlow, Terry
Comparison of Control Strategies of an Electro Hydraulic Valve Actuation System2009-01-02304/20/2009
The Electro-Hydraulic Valve Actuation (EHVA) gives fully programmable variable lift and event duration of the gas exchange valves. Thus the controllability and performance of the gas exchange process in diesel engines can be improved within a range of various load conditions. The dynamic and steady state behavior of the electrohydraulic system can be tuned by selecting the suitable controller. The aim of this study is to compare different control strategies of an electro hydraulic valve actuation system of a middle speed diesel engine. The studied controllers are P- and State Feedback controller. The State Feedback controller is used with or without the velocity and acceleration feedforward loops. The research results are represented through simulations and experimental tests. The operation time range, lifts, and seating velocities etc are shown in the paper.
Herranen, Mika, Virvalo, Tapio, Huhtala, Kalevi, Vilenius, Matti, Liljenfeldt, Gösta
Long-Term Storage of Missile Hydraulic SystemsAIR974A (Historical)11/6/2008
Much of the available long-term storage test data has been reviewed and topically separated to enable the independent discussion of storage effects on fluids, seals, hydraulic components, and hydraulic systems. Comments are made in Section 4 concerning the applicability of the test results and regarding design practices for storability. Conclusions are drawn in Section 5 regarding inactive storage of hydraulic systems for at least a 7 year period.
A-6A2 Military Aircraft Committee
Design of Extended Heavy Trailer's Scraper Style Self-discharging Equipment2008-01-17796/23/2008
The text designed a sort of scraper style self-discharging equipment of extended heavy trailer, solving the problem of using retroversion and side-tipping style to unload automatically in bulk transportation, comparing to manual-discharging, reduced load and unload cost efficiently. The text specified structure and basic work principle of scraper style self-discharging equipment, established engineering model of scraper and brought forward design and calculate method.
Liu, Li, Xia, Huaicheng, Zhang, Hejun, Zhang, Jie, Di, Liming
Dynamic Characteristic Simulation of AT Hydraulic System2008-01-16836/23/2008
Hydraulic system is very important for the performance of AT. The dynamic characteristics of automatic transmission hydraulic system are studied in this paper. Because the valves in the hydraulic system are not standard parts, ITI-SimulationX, the multi-domain physics simulation software from ITI GmbH, is used to build the dynamic model of the hydraulic system based on the basic elements in the library of SimulationX. And then the dynamic characteristics of the system are simulated. The simulation results and the test results from the test bench are compared to confirm the simulation model. The results show that the simulation model can couple with the real system very well and the simulation model can be confirmed. Based on the confirmed simulation model, the effects of different parameters of the hydraulic system on the characteristics of the system are analyzed. Considering the clutch closing process as the optimization objectives, the parameters of the hydraulic system are optimized to solve the problem of clutch failure successfully. The methods in this paper can be used in hydraulic system design and shift control strategy optimization.
Shuhan, Wang, Xiangyang, Xu, Yanfang, Liu, Zhenkun, Dai
Integrated Motor Control Meets Aviation NeedsTBMG-99872/1/2008
The trend in aircraft design is toward more efficient brushless DC motors. A integrated motor drive module for brushless DC motors from International Rectifier (El Segundo, CA) reduces the effort of programming the motor control and simplifies certification. Because the device is configured for sensorless field oriented control, the elimination of Hall sensors improves reliability while reducing component count. It enables the aircraft to achieve greater fuel economy and lower maintenance costs.
Aerospace Fuel System Specifications and StandardsAIR1408A (Historical)12/4/2007
This report lists documents that aid and govern the design of gas turbine powered aircraft and missile fuel systems. The report lists the military and industry specifications and standards and the most notable design handbooks that are commonly used in fuel system design. The specifications and standards section has been divided into two parts, a master list arranged numerically of all industry and military specifications and standards and a component list that provides a functional breakdown and a cross-reference of these documents. It is intended that this report be a supplement to specifications MIL-F-8615, MIL-F-17874, MIL-F-38363 and MIL-F-87154. Revisions and amendments which are correct for the specifications and standards are not listed. The fuel system design handbooks are listed for fuels and for system and component design.
AE-5A Aerospace Fuel, Inerting and Lubrication Sys Committee
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