Browse Topic: Hydrostatic transmissions

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Digital Displacement Hydrostatic Transmission for Rotorcraft and Distributed PropulsionF-0077-2021-168905/10/2021
ABSTRACT
Rancourt, David, Caldwell, Niall, McCurry,  Peter, Stein,  Uwe
Hydraulic Motor Test ProceduresJ746_201911 (Current)11/20/2019
This test code describes tests for determining characteristics of hydraulic positive displacement motors as used on off-road self-propelled work machines as referenced in SAE J1116.
CTTC C1, Hydraulic Systems
Modeling of the Automatic Power Distribution System among the Traction Motors of the Driving Wheels of a Multi-Axle Vehicle2019-01-09144/2/2019
Dynamics of acceleration, mobility, fuel efficiency of wheeled vehicles are largely determined by the drive circuit to the driving wheels and bridges, as well as devices used in drive link nodes to distribute power among the driving wheels. This is especially important for multi-axle wheeled vehicles. In this paper, the object of the study is a multiaxial wheeled vehicle with an electric transmission consisting of an internal combustion engine with a power of 720 kW, one common generator and twelve traction motors mounted directly on the driving wheels. In connection with the change in load on the driving wheels due to the variability of soil properties, driving conditions (acceleration, braking, uniform motion), terrain topography, it is necessary to provide external regulation of electric machines working in the transmission of the vehicle. The aims of the work are: 1) the study of currents and voltages in traction motors while changing the properties of the ground during the movement; 2) modeling of the automatic system providing full loading of the internal combustion engine and optimal distribution of power among the driving wheels with full fuel supply; 3) simulation of an automatic control system for traction motors, which provides the operation of the internal combustion engine with an economical characteristic for partial fuel supply and during acceleration. As a result of the study, the model of the automatic power distribution system among traction motors of the driving wheels of a multi-axle vehicle was developed, which made it possible to provide more efficient operation of the multi-axis vehicle.
Kondakov, Sergei, Pavlovskaya, Olga, Aliukov, Sergei, Smirnov, Vladimir
Development of a Compact and High-Performance Torque Converter Based on a New Parameter Sensitivity Mapping2019-01-13084/2/2019
Automatic transmissions are required to obtain higher efficiency and to reduce their size and weight in order to improve environmental friendliness and fuel economy. Especially in the torque converter development process, there is a need to strengthen the torque multiplication capability to compensate driving force in the non-boost region as a result of recent trends toward engine downsizing. At the same time, there are more rigorous space-saving requirements from the standpoint of ensuring vehicle collision safety. To meet these various requirements, a new torque converter has been developed that provides world-class performance in a minimized torus size. The capacity factor and the torque ratio are the two major parameters of torque converter performance. There are many dimensional parameters concerning the blades and cross-sectional shapes of torus that must be considered in the performance design. It is difficult to optimize these parameters because they involve numerous tradeoffs. In this development project, the quantitative sensitivities between each of the parameters were broadly mapped. As a result, it was found that points existed in every parameter combination for optimizing both performance and size. Such points were found in regions away from those widely used previously in torque converter design. This paper outlines the mapping method used in this project and describes the newly developed torque converter.
Kawashima, Kazunori, Endo, Masatsugu
Selection of Rational Parameters of Automated System of Robotic Transmission Clutch Control on the Basis of Simulation Modelling2019-01-00291/15/2019
The article deals with the analysis of one of the methods of selecting rational parameters of automated clutch control system for robotic transmission. The objective is to select rational parameters of automated clutch control system for robotic transmission, equipped with electropneumatic actuating mechanism on the basis of mathematical simulation. The depicted mathematical simulation of the clutch control system is characterized by the possibility to coordinate the algorithm of control unit with the dynamic processes in the execution device. The new functional interrelations between the elements of the electro-pneumatic actuator are mathematically described. The way to the selection of rational parameters of an automated control system for clutch is recommended; the selection taking into account the features of the electro-pneumatic actuator. Using the mathematical modeling method, rational control parameters of the automated clutch control system are determined. Based on comparative experimental researches, an inaccuracy is calculated for the mathematical modeling of the processes taking place in the electro-pneumatic actuator of a robotic transmission. Analysis of the results of mathematical modeling allowed finding factors that give a competitive advantage in comparison with automated clutch control systems that are used for commercial purposes.
Mikhalevich, Mykola, Yarita, Alexandr, Leontiev, Dmitry, Gritsuk, Igor V., Bogomolov, Viktor, Klimenko, Valeriy, Saravas, Viktoriya
The Fault-Augmented Approach for the Systematic Simulation of Fault Behavior in Multi-Domain Systems in Aerospace2018-01-191710/30/2018
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 results of the fault augmented model are analyzed and using supervised machine learning classifier are demonstrated. Different classification algorithms were compared to each other and analyzed. The accuracy of an appropriate machine learning classifier is analyzed in detail to classify several faults from different domains and to localize their impact by changing a control mode. The selection of relevant output values for the fault classification in the electrohydraulic control system is executed based on the extraction of the feature’s importance.
Kolesnikov, Artem, Andreev, Maxim, Abel, Andreas
Dynamic Stability Analysis of High-Speed Traction Drive CVT for Aircraft Power Generation2018-01-193610/30/2018
The traction-drive integrated drive generator (T-IDG®) has been developed since 1999 to replace current hydrostatic transmission drive generators mounted on Japanese military aircraft. The T-IDG® consists of a generator and a half-toroidal traction-drive continuously variable transmission (CVT), which maintains a constant output speed of 24000 rpm, that is, a 400 Hz AC power supply. To cope with recent trends of more electric aircraft (MEA) and the need for weight reduction, a high-speed traction-drive CVT is advantageous over other transmissions. The torque on the half-toroidal variator is transmitted through multiple power rollers. The equal load sharing among power rollers is typically controlled by a mechanical hydraulic feedback system, whose stability is one of the main issues for the high-speed traction-drive CVT. Previous studies have shown that insufficient damping and stiffness of the mechanical hydraulic feedback system cause self-induced vibration. We found that the support stiffness of the variator also affects the stability of the feedback system when it is driven at a high speed. This paper describes the theoretical criteria to maintain the stability of the load-sharing system of the power rollers of the high-speed CVT. A test to validate the theory is also conducted with a prototype traction-drive CVT at speeds of up to 20000 rpm with a peripheral speed of the traction contact of 70 m/s. The test results show that the vibration is excited at high rotational speeds when the variator is supported with a low-stiffness bearing support. We conclude that a high-stiffness support is necessary to transmit the power stably with a high-speed traction-drive CVT.
Matsuda, Kippei, Goi, Tatsuhiko, Tanaka, Kenichiro, Imai, Hideyuki, Tanaka, Hirohisa, Sato, Yasukazu
Development of a Torque-Based Control Strategy for a Mode-Switching Hydraulic Hybrid Passenger Vehicle2018-01-10074/3/2018
An increase in the number of vehicles per capita coupled with stricter emission regulations have made the development of newer and better hybrid vehicle architectures indispensable. Although electric hybrids have more visibility and are now commercially available, hydraulic hybrids, with their higher power densities and cheaper components, have been rigorously explored as the alternative. Several architectures have been proposed and implemented for both on and off highway applications. The most commonly used architecture is the series hybrid, which requires an energy conversion from the primary source (engine) to the secondary domain. From he re, the power flows either into the secondary source (high-pressure accumulator) or to the wheels depending upon the state of charge of the accumulator. A mode-switching hydraulic hybrid, which is a combination of a hydrostatic transmission and a series hybrid, was recently developed in the author’s research group. This paper focuses on the development of a new controller for the mode-switching hydraulic hybrid prototype. A uniform torque-based control strategy is proposed, which, along-with a supervisory controller decides on the usage of the high-pressure accumulator, thereby switching the vehicle mode from hydrostatic to series hybrid, among others. The supervisory controller analyzes the driving scenario, the system states and the user power demand to select the optimum vehicle-driving mode. This improved control strategy allows the vehicle to operate in higher efficiencies and the uniform control type results in a better “driver-feel”. The development of the control strategies, their implementation on the prototype vehicle and the test results are discussed in this paper.
Banerjee, Pranay, Ivantysynova, Monika
Automotive Transmission TerminologyJ645_201708 (Historical)8/25/2017
The following listed definitions are intended to establish terminology and criteria for describing the various kinds of automotive transmissions. A specific arrangement may be described by a combination of several of these definitions.
Automatic Transmission and Transaxle Committee
Aerospace – System Integration Factors That Affect Hydraulic Pump LifeAIR1922B (Current)2/13/2017
This SAE Aerospace Information Report presents the following factors that affect hydraulic pump life and performance: a The need to supply hydraulic fluid at the correct pressure and quality to the pump inlet port b Considerations for the pump output c Factors to be considered for the pump case drain lines d The mounting of the hydraulic pump e Hydraulic fluid properties, including cleanliness
A-6C4 Power Sources Committee
Fuel Economy Comparison Studies of Forklift Transmission Architecture2015-01-28309/29/2015
Fuel economy is one of the major challenges for both on and off-road vehicles. Inefficient engine operation and loss of kinetic energy in the form of heat during braking are two of the major sources of wasted fuel energy. Rising energy costs, stringent emission norms and increased environmental awareness demand efficient drivetrain designs for the next generation of vehicles. This paper analyzes three different types of powertrain concepts for efficient operation of a forklift truck. Starting from a conventional torque convertor transmission, hydrostatic transmission and a hydraulic hybrid transmission (Eaton architecture) are compared for their fuel economy performance. Eaton hydraulic hybrid system is seen to perform much better compared to other two architectures. Improved fuel economy is attributed to efficient engine operation and regeneration of vehicle kinetic energy during braking.
Agarwal, Shashank, Olson, Michael, Meehan, Tim, Wadwankar, Nachiket
The Increasing Use of Electrical Actuators in the Aerospace and Defense IndustryTBMG-226698/1/2015
Hydraulic and pneumatic systems have traditionally been the market leader in providing power in the aerospace and defense industry because of their low cost and high power density. But in recent years, attention has been focused on the limitations of hydraulic actuators, including their weight, performance, and high maintenance requirements, as well as concerns over their vulnerability due to security issues and other risks.
Integrated Cooling Evaporation System for the Hydraulic Retarder2015-01-16124/14/2015
The hydraulic retarder is a significant auxiliary braking device [1] for the heavy duty vehicle. Traditionally, cooling circulatory system of the hydraulic retarder was coupled with the engine cooling system [2], and the thermal energy of the transmission medium would be cooled by the engine radiator ultimately. For this scheme, radiator's spare heat removal capacity could be fully utilized whereas the cooling system is very complicated and is hard to maintain. Furthermore, the corresponding of thermal management system lags behind the power change of the retarder. In this research, integrated cooling evaporation system is developed for the hydraulic retarder, which makes the cooling water contact with the transmission medium through the stator wall, so that it can rapidly response to the thermal variation of the retarder, keep the stability of the oil temperature and meanwhile reduce the risk of cooling medium leakage. First of all, transmission medium flow regime in the retarder is established for the specific driving condition and the transmission medium flow rate under different gyration radius is analyzed. Then, the integrated cooling evaporation system is designed and its heat transfer model is built in order to analyze the temperature stability of the transmission medium and flow characteristics of the cooling medium under different working conditions. The results show that, compared to the traditional plate-fin heat exchanger [3,4,5,6], the heat-sinking capacity increases 100% to 200% and the transmission medium temperature is in the optimal operating temperature range of 80°C to 120°C. As a result, the real-time control of the thermal management system is better. All of this contributes to the enhancement of the stability and durability of the hydraulic retarder.
Liu, Wei, Tan, Gangfeng, Li, Jiafan, Li, Xin, Mou, Fuzhao, Ge, Yongqiang
Recent Developments in a Novel Blended Hydraulic Hybrid Transmission2014-01-23999/30/2014
A novel Blended Hydraulic Hybrid transmission architecture is presented in this paper with benefits over conventional designs. This novel configuration combines elements of a hydrostatic transmission, a parallel hybrid, and a selectively connectable high pressure accumulator using passive and actively controlled logic elements. Losses are reduced compared to existing series hybrid transmissions by enabling the units to operate efficiently at pressures below the current high pressure accumulator's pressure. A selective connection to the high pressure accumulator also allows for higher system precharge which increases regenerative braking torque and energy capture with little determent to system efficiency. Finally operating as a hydrostatic transmission increases transmission stiffness (i.e. driver response) and may improve driver feel in certain situations when compared to a conventional series hybrid transmission. To explore the novel blended hybrid architecture six transmissions were modeled and simulated. These included baseline manual and automatic transmissions, conventional series hybrid and series hybrid power split transmissions, and the novel blended hybrid and blended hybrid power split transmissions. All six transmissions were then optimally controlled on the UDDS cycle using dynamic programming to remove the influence of controller design on system efficiency. Ultimately the blended hybrid power split transmission improved fuel economy by 17.35% over a baseline automatic transmission while consuming 12.04% less energy than a conventional series hybrid power split transmission. The blended hybrid architecture was further explored by constructing a hardware-in-the-loop test rig and measuring the transmission over a defined drive cycle.
Sprengel, Michael, Ivantysynova, Monika
Quasi-Continuously-Variable Transmission Provides Hydraulic Regenerative Braking for Passenger Cars, Trucks, and Buses2014-01-17174/1/2014
A hydro-mechanical transmission is described that approximates the “gearing” performance of a continuously variable transmission and incorporates all functions required for hydraulic regenerative braking. Other characteristics such as efficiency, noise, and responsiveness, match or exceed that of present day conventional automatic transmissions. Performance and physical sizing are shown for passenger vehicle, bus and truck transmissions.
Lloyd, Robert
Development and Testing of a Hydraulic Hybrid Concept for Off-Highway Vehicles2013-01-24279/24/2013
The paper illustrates the development of a hydraulic hybrid powertrain concept for off-highway vehicles, which is the result of a three-year program at Dana's advanced technology centers. Engineers have conducted extensive simulations and tests while equipping a demonstration vehicle to determine feasibility, develop advanced features, and quantify benefits of hydraulic hybridization for traction. The system concept and operation as well as its development process are illustrated, focusing the system engineering principles and on the model-based approach to system design, control, and energy analysis. Experimental results are provided.
Serrao, Lorenzo, Ornella, Giulio, Burgio, Gilberto, Cosoli, Ettore
Recognition of Operating States of a Wheel Loader for Diagnostics Purposes2013-01-24099/24/2013
In this paper, the operating states of a wheel loader were studied for diagnostics purposes using a real time simulation model of an articulated-frame-steered wheel loader. Test drives were carried out to obtain measurement data, which were then analyzed. The measured time series data were analyzed to find the sequences of operating states using two different data sets, namely the variables of hydrostatic transmission and working hydraulics. A time series is defined as a collection of observations made sequentially in time. In our proposed method, the time series data were first segmented to find operating states. One or more segments build up an operating state. A state is defined as a combination of the patterns of the selected variables. The segments were then clustered and classified. The operating states were further analyzed using the quantization error method to detect anomalies. The recognized operating states define the operation of the machine so the analysis can be focused on specific sections and situations in time series and to identify which kinds of operating situations generate anomalies. Simulated leakages in the main hydraulic components of the hydrostatic transmission and the working hydraulics were used as anomalies to study the changes in the recognized operating states and the magnitude of the quantization error.
Krogerus, Tomi, Hyvönen, Mika, Huhtala, Kalevi
Gas MotorARP719B (Current)6/17/2013
It is intended that this SAE Aerospace Recommended Practice (ARP) will set down guidelines for the development and test of gas motors to provide a practical and reliable hot gas rotary actuation mechanism. Specific operational and test requirements shall be specified in a detail specification.
A-6C4 Power Sources Committee
An Effective Modeling Architecture for MIL, HIL and VDIL Testing2013-01-01544/8/2013
Model based design has proven itself as a key enabler to accelerate the development and enhance the quality of embedded software during the last decade. The tools serving the model based design have continuously improved both in terms of software and hardware, and have achieved a maturity level capable to provide seamless transition across different development phases. This approach provides a capability to ensure the satisfaction of key requirements not only at controls development level but also at system level directly addressing the customer requirements. This paper demonstrates a modeling architecture utilizing this capability, allowing the user work on the complete system model that is capable to maintain the same model architecture starting from pure model simulation phase working its way through vehicle testing, contributing to the reduction of the development time and system integration effort while improving the utilization of the model based tools and methods. The novel approach is presented along with specific examples demonstrating a number of advantages that can be gained through out the development.
Oral, Hamid Alper
Modern and Future Motor Vehicles as Modular-Based Complexes of Mechatronic Systems2012-01-11634/16/2012
The article presents results of comprehensive theoretical and experimental studies aimed at creation of traction-and-transport vehicles (TTVs) - trucks and tractors of the future, which meet the modern requirements for their active and environmental safety. The concept is based on the original complex mathematical model (CMM), which allows simulating various interaction schemes of all TTV systems, including those accounting for the contact (tribological) interaction of the wheel with the rolling surface. The CMM was used to study the work of all the subsystems of TTVs equipped with electric transmission, all-wheel steering and electro-hydraulic servo system of wheel turning, as well as with the wheel-springing system and the onboard information-and-control system. Besides, the CMM and its individual units were used as simulators for programming the functionality algorithms of all these subsystems and their relationships with each other. Based on theoretical studies, unique experimental prototypes of individual systems and of the TTV as a whole were built and experimentally verified. The main conclusion of the studies is the assertion that TTVs should be built as complexes of modular-based mechatronic systems. An ideal TTV is a mobile robot of universal functionality.
Beloousov, Boris Nikolaevich, Ksenevich, Tatiana
Analysis and Guidelines for Design of Efficient Power-Split Systems2012-01-03044/16/2012
The article is divided into two parts. The first part is dedicated to the analysis of mechanical systems by means of the matrix method. The power of the matrix method lies in its easy implementation in computer calculations. In this article we will present the program “SunGear.” This program is devoted to calculation of such Power-split systems and complete analysis of mechanical stepped planetary gearboxes. The second part of the article will describe the analysis of Power-split systems. In our study we focus on Power-split systems with mechanical CVT. The analysis will be presented by means of two examples: a) IVT (no shift elements) with the spread from reverse (ratio equals −2) up to the overdrive with a ratio of 0,6. The power is split between CVT (spread 0,25 up to 4) and mechanical gear set. The differential (planetary or bevel gear device with 2 degrees of freedom) is placed on the input or on the output of the mechanism. A set of 24 different compositions of mechanisms which fulfill the given kinematic constraints was obtained. The comparison of all found solutions is made mainly based on the overall efficiency and magnitude of circulating power. According to the analysis the guidelines for design of an efficient IVT system were developed. b) Power-split CVT, where the combination of differential, CVT and mechanical gearset is made mainly to increase the torque capacity in case of usage of mechanical CVT and for increase of efficiency in case of usage of hydrodynamic of hydrostatic CVT. As distinct from the IVT's the Power-split CVT systems can be designed without circulating power. The guidelines of design of Power-split CVT systems without circulating power will be presented.
Achtenova, Gabriela, Budinsky, Tomas
Aerospace - System Integration Factors That Affect Hydraulic Pump LifeAIR1922A (Historical)1/3/2011
This AIR presents the following factors that affect hydraulic pump life and performance: a The need to supply hydraulic fluid at the correct pressure and quality to the pump inlet port b Considerations for the pump output c Factors to be considered for the pump case drain lines d The mounting of the hydraulic pump e Hydraulic fluid properties, including cleanliness
A-6C4 Power Sources Committee
A Power-Split Hybrid Hydraulic Vehicle Transmission Modeling and Comparative Analysis2010-01-201010/5/2010
Recent innovative drives in hydraulics could introduce very competitive hybrid hydraulic vehicles (HHV). These drives has been considered and analyzed only in the serial HHV architecture. The series-parallel transmission architecture, also called power-split or e-CVT is highlighted as the most popular concept for full (strong) hybrid electric vehicles (HEV). The examples are one-mode power-split in Toyota Prius and two-mode (compound) power-split in GM-Allison EVT. Ambitions to make the hybrid hydraulic power trains better and more efficient would certainly require deeper analysis of more complex power-split (series-parallel) HHV transmission structures and related optimal controls. This paper presents bond graph based mathematical model of kinematics of a one-mode and a two-mode power-split hybrid hydraulic vehicle transmissions which are based on their hybrid electrical counterpart. Such models serve as a basis for the analysis of the steady-state behavior of two representative power-split HHV transmissions. The analysis encloses the power train power flow. Related consideration of limitations and possible energy recuperation is given, too. Obtained kinematics mathematical models provide the basis for their upgrade with dynamics effects using bond-graphs, and the example is given in the paper, as well.
Petric, Josko
Hydraulic Motor Test ProceduresJ746_200906 (Historical)6/12/2009
This test code describes tests for determining characteristics of hydraulic positive displacement motors as used on construction and industrial machinery as referenced in SAE J1116. These characteristics are to be recorded on data sheets similar to the one shown in Figure 1. Two sets of data sheets are to be submitted: one at 49 °C (120 °F) and one at 82 °C (180 °F).
CTTC C1, Hydraulic Systems
Automotive Transmission TerminologyJ645_200903 (Historical)3/3/2009
The following listed definitions are intended to establish terminology and criteria for describing the various kinds of automotive transmissions. A specific arrangement may be described by a combination of several of these definitions.
Automatic Transmission and Transaxle Committee
Synchronized drivingOFHMAR09_013/1/2009
Tight linkage between engine and transmission increases efficiency. Electronic controls are extending their reach, managing transmissions to improve performance and fuel economy. This transformation comes as engineers focus on ways to synchronize all functions of a vehicle. Now that microcontrollers are a central part of engine design, they are becoming tightly synchronized with transmissions and hydraulic systems. This holistic approach to vehicle design lets engineers do far more fine tuning than is possible with mechanical transmissions.
Costlow, Terry
New Generation Hydraulic-Mechanical Transmission with Lock-up Mechanisms and Automatic Start Clutch2008-32-00409/9/2008
New Generation Advanced Hydraulic-Mechanical Transmission (A-HMT) with the Lock-Up mechanism and the automatic start clutch mechanism was developed. In the lock-up mechanism, an electronic control in conjunction with transmission control was adopted using oil temperature, throttle opening, and input / output rotation ratio as parameter to reduce a rotational energy change of input and output axis caused by the volumetric efficiency of A-HMT. In the automatic start clutch, the load sensing function, damper function, and cooling function by replacing the simple hydraulic mechanism are equipped. By these solutions, the transmission efficiency has enhanced approximately 10% compared with former A-HMT, and excellent starting performance and smooth transmission performance have achieved.
Yoshida, Yoshihiro, Yakigaya, Nobuyuki, Nakamura, Kazuhiko, Takeuchi, Kazuhiro, Nakano, Kenichi, Usukura, Yasutaka
Lean Cr Containing PM Materials for Optimized Cost-Performance2008-32-00749/9/2008
Cr containing PM steels aid optimization of cost-performance for power transmission components in hydrostatic transmissions. Components such as final drive gears and differential gear sets are typical manufactured from sintered materials containing high levels of alloying elements such as Cu, Ni and Mo. Utilisation of Cr-Mo PM materials presents materials with improved cost - performance ratio via improved materials properties combined with improved dimensional tolerances.
Milligan, David, Howe, Ian, Haberberger, Thomas, Cerini, Richard
Gas MotorARP719A (Historical)11/6/2007
It is intended that this SAE Aerospace Recommended Practice (ARP) will set down guidelines for the development and test of gas motors to provide a practical and reliable hot gas rotary actuation mechanism. Specific operational and test requirements shall be specified in a detail specification.
A-6C4 Power Sources Committee
Fendt Vario CVT in Agricultural Tractors2007-01-420510/30/2007
This presentation shows the concepts and the advantages of the Fendt Vario CVT and the features that have been developed to enhance its use in agricultural tractors. The Fendt Vario transmission has been in production for more than 10 years with more than 60,000 tractors built with this CVT concept (until the first half of 2007, Fendt and OEM). As examples emphasize, the CVT helps to optimize the usable power and the fuel economy - especially when compared to power shift transmissions. The machine productivity is further improved by a variety of features like cruise control or constant engine speed for PTO operation with variable ground speed. Acceleration rates are adjustable and reversing can be accomplished with best operator comfort. Further automation and operation systems make the CVT tractor fit to high-end applications. A macro-instruction system allows the driver to store multiple operations. Other main characteristics of a tractor for professionals are mentioned, e.g. anti-roll system, auto-guidance.
Brenninger, Martin M.
Study of Energetic Characteristics in Power Split Drives for on Highway Trucks and Wheel Loaders2007-01-419310/30/2007
Continuously variable transmissions (CVT) have been gaining popularity because they decouple the engine of a vehicle from the vehicle wheels, providing seamless shifting in vehicle operation and allowing the engine to operate in a speed range where fuel consumption and emissions are minimized. In particular, the power-split CVT, or power split drive (PSD), combines the variability of a CVT with the high efficiency of a mechanical transmission, providing potential benefits for both on road and off road vehicles. Hybrid PSDs allow further fuel savings by transferring the vehicle's kinetic energy to an energy storage device such as a battery, flywheel, hydraulic accumulator or other means during braking and utilizing the stored energy during the next propulsion cycle. While many power split configurations exist in literature (Miller 2005), this paper focuses on a dual stage input coupled PSD with a flywheel energy storage device. The objective of this research work is to describe the mechanism of energy recovery for the dual stage PSD with flywheel energy storage and demonstrate the transmission's energy recovery capabilities. To accomplish the latter task simulations for two specific applications, a wheel loader and a highway truck, demonstrate the energy saving potential of the hybrid dual stage PSD when compared to the standard dual stage PSD.
Kumar, Rajneesh, Ivantysynova, Monika, Williams, Kyle
A numerical model for the simulation of Diesel/CVT power split transmission2007-24-01379/16/2007
This paper presents a steady-state numerical model of a power split hydro-mechanical input-coupled transmission for off-road vehicles. In this kind of transmissions the combustion engine is connected to a planetary and to a hydrostatic unit. Depending on vehicle speed and power request, the power is transmitted either hydrostatically or mechanically, or in both ways. The performance of the Diesel engine has been simulated in a simple manner by means of a look-up table, based on the specific fuel consumption map; a similar approach has been adopted for the efficiency of the hydrostatic units. The code is able to predict the overall efficiency of the powertrain, while highlighting the contributions of the hydrostatic path, of the mechanical path and of the engine. The results show how the code can be used both for locating the optimum operating point, as a function of the specific duty, and for analysing different configurations of the transmission.
Casoli, P., Vacca, A., Berta, G.L., Meleti, S., Vescovini, M.
Construction and Tests of Swimming Vehicle with Diesel-Hydraulic Power Transmission Feed, Assigned for Special Operation Forces (SOF)2007-01-14244/16/2007
Siminski, Przemyslaw, Zienowicz, Zbigniew
Analysis of a Hybrid Multi-Mode Hydromechanical Transmission2007-01-14554/16/2007
A multi-mode hybrid hydromechanical transmission (HMT) with infinite variability is designed to meet the power transmission needs of medium duty on- and off-road vehicles. A hydraulic pump-motor assembly provides output speed and torque variability in an input coupled split power configuration. Dual planetary arrangements with two multiplate clutches allow multi-mode ratio change and combination of power from the mechanical and variable branches of the power path. Hydraulic accumulators offer hydraulic power assist during launch conditions and storage of reclaimed energy during braking events. Transmission kinematic, force and power flow analyses will be developed for the HMT and analyzed for suitability in a bus application. The resulting benefits and areas for improvement will be discussed.
Fussner, Doug, Wendel, Glenn, Wray, Chris
Comparison of Operational Characteristics in Power Split Continuously Variable Transmissions2006-01-346810/31/2006
Continuously variable transmissions (CVT) provide seamless shifting in vehicle operation, allowing the engine to operate at a nominal speed range resulting in lower fuel consumption and emissions. However, typical CVTs suffer from either low shaft-to-shaft efficiency or low torque handling capabilities. The power split CVT combines the variability of the CVT with the efficiency of a mechanical transmission, providing potential benefits for both on road and off road vehicles. By modifying the architecture and layout of a power split transmission, the characteristics and maximum speed of the vehicle drive cycle can be altered. This paper will present a comparison between the different architectures of power split transmissions utilizing hydraulic units as the variators, with a focus on efficiency, control effort, and system complexity. Applications based on the characteristics of the specific transmission architectures will be suggested.
Carl, Blake, Ivantysynova, Monika, Williams, Kyle
The Prototype and the Simulation Results of Hydraulic Power Transmission of Teleoperated Skid Steered Mobile Machine2006-01-347010/31/2006
The goal of the paper is to study the properties of a teleoperated mobile machine by means of simulation model of the system and measurements. In this paper some parts of the prototype of the teleoperated machine and the verification results of simulation model of the mobile machine are introduced. The challenge in teleoperation is to have a smooth and accurate control of the machine, because the operator can not feel any force feedback. The machine is valve controlled and the influence of different types of valves is significant for the control of the machine. In this paper is studied via simulation model different kind of valve solutions such as different spool types and effect of pressure compensator among others. The goal in future is to have a totally autonomous mobile machine and it needs more research and development work. With simulation model of the machine it is possible to test new components and hydraulic solutions for power transmission of the mobile machine. In paper autonomous land vehicles [7] is described the current state-of-the-art in autonomous land vehicle systems and technology. Around the world there are many current research and development projects aimed at developing autonomous land vehicles. The goal of this study and research work which results is presented in this paper is in future to have autonomous mobile machine. This machine is equipped with mobile hydraulic components and of commercial point of view the cost of the machine should be as low as possible. This is the reason why also companies are interested of this work and the development and research work is very challenging.
Vilenius, J., Hyvönen, M., Vuohijoki, A., Karhu, O., Moya, J., Huhtala, K.
Electrically Controlled Fixed-Displacement Pump, Variable-Displacement Motor Hydrostatic Transmission2006-01-346910/31/2006
Fixed-displacement pump, variable-displacement motor configurations are rarely utilized for hydrostatic transmission designs, but they can achieve several advantages over more traditional systems. Developing a hydraulic drivetrain to accomplish high efficiency at high torque is often difficult because variable-displacement pumps are less efficient at low displacements. However, a system that utilizes modern electro-hydraulic valves and an electrically controlled variable-displacement hydraulic motor is easy to modulate and achieves its peak efficiency at low speeds. During the 2005 ASABE (American Society of Agricultural and Biological Engineers) ¼ Scale Tractor Student Design Competition, one such system was compared to conventional hydrostats and belt driven continuously variable transmissions. The fixed pump, variable motor system proved to be easy to operate. An electronic controller was used to modulate motor displacement to maintain constant engine speed. From data gathered during the performance event, it was observed that the system utilized engine power more effectively than traditional hydrostatic transmission configurations.
Holland, Michael A., Harmeyer, Keith, Lumkes, John H.
Hydraulic mattersOFHAPR05_034/1/2005
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.
Ries, Richard
Drive Line Control for Off-Road Vehicles Helps to Save Fuel2004-01-267310/26/2004
A new control concept was developed to minimize the power losses of a hydrostatic drive line for off-road vehicles. The drive line control concept is based on two separate closed loop controls, one for the hydrostatic transmission and another for the combustion engine. The command values for both control loops are calculated under consideration of the characteristic curves of the combustion engine and the losses within the hydrostatic transmission, using an on-line optimization procedure. This paper discusses the benefits of this control concept based on a comparison of typical realistic driving manoeuvres. Objective of the investigations for different output powers is the potential of fuel savings under different operating conditions. A hardware-in-the-loop test rig for the investigated hydrostatic propel drive is used for the experimental validation.
Ossyra, Jean-Claude, Ivantysynova, Monika
Power Split Transmissions Versus Hydrostatic Multiple Motor Concepts - A Comparative Analysis2004-01-267610/26/2004
The aim of the presented study was to analyze the potentials of two different drive line concepts. The comparison is made for a simple Power Split Drive and a Hydrostatic Two-motor Transmission with a disconnectable hydromotor. The main focus is put on the achievable overall efficiency of both alternatives. The system complexity of the two compared transmissions is very different. The analysis therefore also looks towards this matter and further makes an assessment of the different control requirements.
Krauss, Alexander, Ivantysynova, Monika
Changing demands reshape hydraulic componentsOFHAPR02_014/1/2002
In a world of shrinking margins, fierce competition, and increasing regulations, equipment owners want nothing less than stellar performance from their equipment. New technology helps off-highway OEMs respond to equipment-owner demands for faster, cheaper, and more reliable vehicles. So do new business practices: most OEMs are compelling suppliers to re-examine their technologies and practices. “OEMs are trying a purchase strategy much like that used by the automotive people where you have Tier 1 and Tier 2 suppliers,” said Joe Maher, Marketing Manager, Poclain Hydraulics. “The idea is that if they can consolidate their suppliers, those suppliers (will) have more volume, which should generate some cost reduction. And because you're dealing with fewer suppliers, you've saved some administration cost, as well.”
Ries, Richard
Food-Grade Fire-Resistant Water Glycol Hydraulic Fluids2002-01-15043/19/2002
Fire is a serious hazard in many industrial applications requiring the use of approved fire-resistant hydraulic fluids. A subgroup of these applications are facilities for the processing of food which in addition require hydraulic fluids and other lubricants used in these facilities to adhere to specifications set down by the United States Food and Drug Administration (FDA) and enforced by the Food Safety Inspection Service (FSIS) branch of the U.S. Department of Agriculture (USDA). The objective of this paper is to provide an overview of the current requirements in the United States for food-grade fire-resistant hydraulic fluids. Water glycol type hydraulic fluids; currently the only commercial food-grade fire resistant hydraulic fluids available, are compared in properties and performance to standard water glycol hydraulic fluids used in steel making and die casting facilities.
Sherman, J. V., Totten, G. E.
The Method of Great Efficiency Improvement in Continuously Variable Integrated Hydrostatic Transmissions2002-01-14203/19/2002
In this paper a simple technical solution is presented. This solution allows a significant reduction of a wear of parts in an integrated hydrostatic transmission as well as a great efficiency improvement. This solution is suitable for all types of integrated hydrostatic transmissions and it is easy in application.
Stroganov, Alexander, Drouzhinin, Alexander, Volkov, Yuriy, Zimnikov, Alexander
Concepts and Development Trends for Efficiency Improvement of Hydrostatics in Mobile Applications2002-01-14223/19/2002
In mobile vehicles such as earth moving machines, agriculture machines, forest machines, industrial and mining lifters there is a demand for sophisticated performance. Since the requirements on productivity are very high for mobile machinery, high output capacity combined with high overall efficiency over a wide velocity range is therefore of great importance. A traditional solution for drive train in mobile machinery is to use a hydrodynamic transmission (torque converter) in series with a multi-speed shiftable gearbox. For heavy machines, engine power above 150 kW, torque converters have been used exclusively until a few years ago. However, the development of hydrostatic drive concepts and microprocessor control have made it possible to be competitive with converter drives. Joining pumps, motors and mechanical gears in smart concepts, so called power split transmissions, has make it possible to keep prescribed output power and velocity range without the need of sophisticated power shift gearboxes. In constant pressure hydraulic systems gas loaded accumulators can be used for energy storage. During braking and lowering of loads, the kinetic energy of the load can be stored in the accumulator and then the energy will be reused for acceleration and lifting of the load. Secondary controlled motors and hydrostatic transformers are components that can be used in conjunction with accumulators to improve the overall efficiency of hydrostatic systems. The need is also growing for technology that is capable of not only efficiently producing high-quality works, but also being environmentally friendly. In that sense, high efficient hydrostatic systems with good controllability would be extremely useful in a large quantity of outdoors industrial applications. The aim of this paper is to show how the advantage of hydrostatics can be exploited to reach high capacity, high overall efficiency and controllability required for high productivity.
Rydberg, Karl-Erik
An Off-Road Competition Hydraulic Vehicle2002-01-14503/19/2002
A 4-wheel drive off-road vehicle was designed and fabricated using extensive hydraulic technology for the SAE (Society of Automotive Engineers) Mini-Baja competition. The vehicle incorporates an open hydrostatic transmission using a single pump and four independent drive motors. A constant power controller that maintains full engine power to drive the vehicle or stores excess energy in two accumulators controls the pump. Each of the drive motors is independently controlled using a proportional meter-out pressure control valve. The use of pressure control allows the flow to each of the motors to be proportioned based on the dynamics of the vehicle. A CAN bus controller is used in conjunction with a steering sensor to provide differential motor speed control in maneuvering conditions that insures 4-wheel drive availability at all times. Steering of the vehicle is achieved by articulating the chassis using a rotary actuator and multi-motion actuator controlled by the driver. Incorporating these features in the vehicle results in a very small turning radius relative to traditional competition vehicles. The use of the hydrostatic transmission allowed the engine to be moved to the front of the vehicle giving a better weight distribution and making the 4-wheel drive effective throughout the range of the competition. Storing the excess energy in accumulators provided a “power boost” capability beyond the fixed engine power level that could be used to accelerate out of turns or pass on straight-aways. The CAN bus controller allowed the car to be “tuned” to track conditions without the need for extensive hardware changes or modifications.
Labus, Thomas J., Wasielewski, Paul
New Method of Numerical Calculation of Losses and Efficiencies in Hydrostatic Power Transmissions2002-01-14183/19/2002
The present paper describes a newly developed method of computing the losses and efficiencies of hydrostatic power converters. Unlike previous methods this approach is not based on a physical/technical analysis of a single hydraulic pump or motor type. Instead, it employs purely mathematical methods based on measurement data to provide a universally applicable method for computing the power and efficiency behavior of hydrostatic machinery of any design. The accuracy of the method is confirmed by a comparison of measured and calculated performance and efficiency data.
Ortwig, Harald
Development of Single Stage Input Coupled Split Power Transmission Arrangements and their Characteristics2002-01-12943/4/2002
In recent years there has been an increased interest in the continuously variable split power transmissions as these drive units are capable of vehicle launches and directional changes without using clutches. These tasks are accomplished by appropriately splitting power between the fixed mechanical and variable ratio branches. The power is recombined at the transmission output. A properly designed split power transmission arrangement will improve vehicular agility and reduce variator size. This paper provides characteristics of six single stage input coupled continuously variable toroidal split power transmission arrangements. Mathematical equations are derived for speed, torque and power. A computer program that utilizes the capabilities of Matlab is developed. The program calculates the required fixed and variable branch gear ratios for the predefined variator, planetary and overall transmission ratios. Further, the program produces numerical results and visual plots of relationships between transmission ratio, variator ratio, planetary ratio, and the power flow through the transmission branches. Characteristics of the transmission arrangements are analyzed and compared and documented. Suggestions for practical use of the split power transmissions are given and methods to reduce the recirculated power through the variable and fixed branches are provided.
Fussner, Doug, Singh, Yesh
SAE Off-Highway Engineering 2001-10-01OFHOCT0110/1/2001
More with less through electronic components Off-highway engineers have had to walk a precarious path in recent years by developing engine technologies that offer customers better vehicle performance and regulators lower emissions. The promises and problems of electrohydraulics Engineers acknowledge that electrohydraulics are the way of the future for the off-highway industry, and that the field itself could use a good public-relations campaign to attract more engineering students. Deere goes all out for agriculture To some, it may seem odd that John Deere picked this particular economy to launch over 50 new products, the most in its 164-year history. To others it reeks of confidence. Switching control in hydraulic drives Researchers from Johannes Kepler University believe agricultural machinery can be improved by further advances in motion generation.
SAE Off-Highway Engineering 2001-02-01OFHFEB012/1/2001
Hydrostatic transmissions in conventional envelopes Kubota designed a hydrostatic transmission for a compact tractor to improve operator control and increase efficiency and productivity. Design of a hydraulic free-piston engine Dutch companies Noax and Innas have developed an engine in which nearly all combustion energy is directly converted into hydraulic energy. Optimizing tractive performance Canadian researchers correlate analytical predictions and experimental data to determine that the proper matching of front- and rear-tire sizes, aswell as careful control of inflation pressure and normal load of the tires, is necessary to achieve optimum tractive performance of four-wheel-drive tractors. Actively suspending off-road vehicles The University of Texas Center for Electromechanics evaluated a retrofit electromechanical active suspension that s hows promise of improved cross-country mobility for military vehicles.
Improved Reliability Brake Pneumatic Drive2000-01-26399/11/2000
The main requirements to which the brake system of a vehicle should respond are provision of the standard operation speed and protection features of the control pneumatic drive in case of a malfunction of any of its elements. The article describes a design of modified pneumatic brake drive having improved protection properties in case of damage of a diaphragm of any brake chambers, and methodology of parameter optimization of such drive allowing to create a layout of drive assemblies with the necessary operation speed for MAZ truck-based road trains.
Uspenskiy, Alexander, Pavlovich, Alexander
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