Automated Mechanical Transmission Controls

<div class="section abstract"><div class="htmlview paragraph">Automatic transmission (AT) is a complex hydroelectromechanical system, since it consists of hydraulic, electrical and mechanical parts.</div><div class="htmlview paragraph">On cars produced by “UzAuto Motors” mainly AT of the 6T family, 6-speed AT family GM: 6T30, 6T40, 6T45, 6T50 “Hydra-Matic” are used.</div><div class="htmlview paragraph">Production of parts of these transmissions is carried out both at American GM plants and at GM plants in China and Korea.</div><div class="htmlview paragraph">The differences between AT 6T30/6T40/6T45/6T50 are in the thickness of the output chain and in the planetary gear, in the sizes of some other units and the housing itself. But the differences are much more influenced by the settings of the transmission unit, which select operating modes with different engines so as not to overload the thinnest places of the automatic transmission.</div><div class="htmlview paragraph">Automatic transmissions 6T30, 6T40, 6T45, 6T50 have the ability to manually shift gears and activate the “kickdown” mode (for quick acceleration of the car, when you sharply press the gas “all the way” it makes the automatic transmission downshift, and sometimes by two steps).</div><div class="htmlview paragraph">The operation of the transmission is controlled by various electronic systems that are responsible for the operability and structural integrity of the gearbox.</div><div class="htmlview paragraph">Failure of the automatic transmission can occur as a result of one or a combination of malfunctions of the following parts: in the torque converter; in the mechanical part of the gearbox; in the hydraulic part of the control system; one or more clutches of the gearbox; in the electrical part of the control system; in the electronic control unit.</div><div class="htmlview paragraph">The authors of the work investigated and determined the occurrence of malfunctions and failures depending on the temperature of the working fluid of the automatic transmission of a passenger car.</div><div class="htmlview paragraph">Also, the dependence of the resource of the automatic transmission on the temperature of the hydraulic fluid was obtained. High-quality diagnostics of the automatic transmission and its control system can in many cases save the car owner from expensive repairs: <ul class="list disc"><li class="list-item"><div class="htmlview paragraph">without thorough diagnostics, the automatic transmission cannot be subjected to routine or major repairs. Only on the basis of diagnostic information can a conclusion be made about the technical maintenance or repair of the automatic transmission;</div></li><li class="list-item"><div class="htmlview paragraph">based on real experience of operating passenger cars equipped with automatic transmission, we recommend changing the oil every 35000 miles under operating conditions in Tashkent. We also recommend conducting diagnostics of the automatic transmission every 12500 miles of the car's mileage.</div></li></ul></div></div>

<div class="htmlview paragraph">Hino Motors had developed an electronically controlled mechanical automatic transmission and employed it for the ′85 models of large size buses, and also ′86 models of heavy/ medium duty trucks. This system gives minimum fuel consumption and even smoother/easier driving than an automatic transmission with torque converter, by controlling an engine also with a transmission and employing an oil spray clutch. The trade name of this system is EE-Drive which means easy and economy drive.</div>

<div class="section abstract"><div class="htmlview paragraph">The parameters determining shift quality control in automatic transmissions are determined as part of the calibration of the transmission control. The resulting control system typically has three components: feedforward control, where the control output is determined before a gearshift; feedback control, where the control output is determined during the gearshift based on sensed feedback; and learning control (adaptation), where the feedforward or feedback controller parameters are modified after the current gearshift has ended and before the next similar gearshift begins. Gearshifts involving the same ratio change are referred to here as similar gearshifts, though such gearshifts may involve differences in other variables such as vehicle speed or engine torque. In most automatic transmissions, gearshifts are controlled by hydraulic clutches, and operating conditions for these clutches may vary widely, requiring a dedicated transmission controller involving significant calibration effort.</div><div class="htmlview paragraph">In the current work, novel model-based methods are used to accomplish feedforward control of gearshifts, involving offline calibration of fill and torque phase control parameters and learning control of the fill phase. Towards this end, a physics-based model of the oncoming clutch involved in an upshift of a production automatic transmission was developed and experimentally validated against test bench experiments for a wide variety of inputs and operating conditions. The resulting model is used to generate a feedforward controller, offline model-based calibration algorithm, and a learning controller that corrects for clutch under-fill and over-fill. The effectiveness of the resulting controller is validated by simulation studies using the experimentally validated transmission hydraulic system model, in conjunction with a powertrain model. In particular, it is demonstrated that the learning controller corrects for initial under- or over-fill error in two to three gearshifts. Convergence and robustness properties, and transient performance of the learning controller are also discussed.</div></div>

<div class="section abstract"><div class="htmlview paragraph">This paper presents a methodology to represent automatic transmission clutch-to-clutch shift dynamics with a two degree of freedom, lumped inertia model. The method of reducing the automatic transmission to a lumped, two inertia model as a function of shift and input shaft acceleration is detailed using a full kinematic representation of the automatic transmission. For a given clutch-to-clutch shift maneuver there are two dependent equations that utilize the two lumped inertias and represent the response of the transmission system from input to output shaft. Applicability of the method is shown for planetary automatic and layshaft dual clutch transmissions. Typical clutch-to-clutch shift maneuvers are illustrated with the two inertia model for power on upshifts and downshifts. The simplification of automatic transmission shift dynamics using this method enables rapid synthesis of a given transmission powerflow for estimation of shift quality potential, required clutching torques, inertia phase engine torque intervention and output torque through all phases of a shift event.</div></div>

<div class="section abstract"><div class="htmlview paragraph">The worldwide increasing acceptance and success of modern automatic transmissions in passenger cars is based on innovative technology, driving comfort, shifting dynamic and - most important - fuel consumption reduction.</div><div class="htmlview paragraph">New concepts are facing the challenge of further improvements in internal efficiency and very tough future goals on CO2 emissions in connection with more sophisticated gasoline and diesel engine technologies. Based on the competition and current diversity in automatic transmission concepts, high investments in production facilities must be taken also well into account when thinking about follow-up technologies of installed 8-speed and 9-speed technologies. This must also be considered for the different demands in regions and markets.</div><div class="htmlview paragraph">So, how may a successful automatic transmission system look like in 2020 and beyond? Do we have even more gears than the current 8-speed and 9-speed? Does it make sense to increase the total gear ratio any further? Are there measures to improve the overall mechanical efficiency by several percent? What is the prevailing transmission system: torque converter planetary, dual-clutch countershaft or belt-type stepless transmission? How does the electrification and hybridization of the powertrain in the next years effect the system?</div><div class="htmlview paragraph">This article will give some brief answers on how ZF is planning the future of automatic transmissions and how successful systems should look like.</div></div>

<div class="htmlview paragraph">This paper introduces mathematical equations for power loss calculations of major automatic transmission components.</div> <div class="htmlview paragraph">It also presents a theoretical investigation on contributions of each component's power loss to transmission total power losses.</div> <div class="htmlview paragraph">A computer program for automatic transmission efficiency calculation has been developed based on mathematical equations.</div> <div class="htmlview paragraph">Efficiency calculations for the Hyundai A4BF1 electronic 4 speed automatic transmission has been executed in order to validate the program.</div> <div class="htmlview paragraph">The calculated efficiency under various input and operating conditions - such as different input torque & RPM, transmission gear state, ATF temperature, torque converter clutch on/off - showed quite good agreement with the test results.</div>

<div class="htmlview paragraph">This paper presents a general discussion of automatic transmission parasitic losses and efficiency characteristics.</div> <div class="htmlview paragraph">Efficiency characteristics of the three major automatic transmission components-pump, torque converter, and gearbox-and their contribution to the transmission total torque losses are examined. A data reduction method for isolating gearbox torque losses from total transmission losses is also described.</div> <div class="htmlview paragraph">The information presented is based on pump, torque converter, and transmission testing performed at SwRI for Ford Motor Company. Test data was used to perform analytical fuel economy benchmarking studies. Testing included 13 transmissions manufactured by American, European, and Japanese manufacturers for 3.0-5.8L truck applications.</div>

<div class="htmlview paragraph">A new automatic transmission called the CEEMAT (Converter Enhanced, Electronically Managed, Automatic Transmission) has been developed to serve the on/off highway truck market. The CEEMAT was also specifically designed to suit military applications.</div> <div class="htmlview paragraph">The CEEMAT is a unique combination of currently available mechanical transmission products and the power and sophistication of electronic control.</div> <div class="htmlview paragraph">The CEEMAT provides ample ratio coverage with proven reliability. Fuel economy can also be improved because of extended torque converter lockup function and the overdrive ratio.</div>

<div class="htmlview paragraph">The most common driveline configurations in cars are the standard drive with front longitudinal engine and rear wheel drive and the front-transverse drive with east west installed powertrain as well as all-wheel drive variants derived from these. These driveline configurations are used in different vehicle segments. The transmission systems mainly used today are automatic transmissions with 4 or 5 speeds and manual transmissions with 4, 5 or 6 speeds. A small number of automated manual transmissions (AMT) and continuously variable transmissions (CVT) are in production. Various systems of automated manual transmissions, powershift transmissions designed as double clutch transmissions and toroidal transmissions are currently being developed.</div> <div class="htmlview paragraph">A brief explanation will be given about the structure of all different driveline configurations and the transmission systems will then be considered for specific applications in these different drivelines. The installation situation with transmission structure and space, potential for fuel savings with overall ratio and efficiency, reduction of emissions and noise levels, performance, drive comfort, transmission weight and manufacturing costs are considered as the main aspects within this paper. This leads to an assessment and recommendation for the use of certain transmission systems for the various driveline configurations.</div> <div class="htmlview paragraph">In the future, both 6-speed automatic transmissions and 6-speed manual transmissions will be used on a wider scale with standard drives. The use of continuously variable transmissions will increase for front transverse drive. In the field of manual transmissions the 5-speeds will dominate in front transverse drive applications. The degree of automation will increase in this segment. For torque levels of up to approximately 180 Nm, preference will be given to the use of automated manual transmissions. The range of up to 350 Nm will be predominantly covered by CVT's, five and six-speed automatic transmissions will subsist in the segment above 350 Nm for transverse installation.</div>

<div class="htmlview paragraph"><b>STARTING with the Sturtevant in 1904, transmission developments are reviewed to date. Requirements for successful and satisfactory automatic transmissions are discussed and interpreted in the light of present and future development.</b></div> <div class="htmlview paragraph"><b>Six tables that classify transmissions comprise the nucleus of this part. These tables group the methods of varying the speed; the means of control; the gear engagement or connection; the shifting methods; clutches; and clutch control.</b></div> <div class="htmlview paragraph"><b>THE story of over two million miles of operating experience using the “Mono-Drive” type of automatic transmission on 101 passenger buses in Chicago, is told in the second part of the paper. The mechanical operation of this automatic transmission is explained, and specifications and data are given on the buses in which they are used. A review of the maintenance record of the transmissions concludes the paper.</b></div>

<div class="section abstract"> <div class="htmlview paragraph">This SAE Recommended Practice is intended as the definition of a standard test, which may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use.</div> <div class="htmlview paragraph">The SAE No. 2 Friction Test Machine is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluids. It can also be used to conduct durability tests on wet friction systems.</div> <div class="htmlview paragraph">The specific purpose of this document is to define a µPVT Test for the evaluation of the variation of wet friction system performance as a function of speed, temperature, and pressure. This procedure is intended as a standard for both suppliers and end users.</div> <div class="htmlview paragraph">The only variables selected by the supplier or user of the friction system are:</div> <ol class="list nostyle"> <li class="list-item"> <span class="li-label">a</span> <div class="htmlview paragraph">Friction material</div></li> <li class="list-item"> <span class="li-label">b</span> <div class="htmlview paragraph">Fluid</div></li> <li class="list-item"> <span class="li-label">c</span> <div class="htmlview paragraph">Reaction plates</div></li></ol> <div class="htmlview paragraph">These three variables must be clearly identified when reporting the results of this test. If any of the test parameters or system hardware as described in this document are changed, other than the friction material, test fluid, or reaction plates, the data may not be reported as having been obtained using this document.</div> <div class="htmlview paragraph">This procedure is intended to evaluate the midpoint, endpoint, and breakaway coefficients and endpoint/midpoint ratios. The procedure can be used to demonstrate changes that occur between the different levels of engagement speed, sump temperature, and apply pressure. Refer to SAE J2487, SAE J2488, or SAE J2489 for coefficient variations due to changes in power level.</div> <div class="htmlview paragraph">The procedure, as described in detail in <span class="xref">Table 1</span>, consists of four 50 cycle break-in levels at 3500 rpm with increasing steps of apply pressure, followed by 16 levels consisting of 25 dynamic engagements, and one breakaway following completion of the 25th dynamic cycle. The 16 levels are achieved by varying initial engagement speed, apply pressure, and oil sump temperature while the inertia is kept constant at 0.701 kg/m<sup>2</sup>.</div></div>

<div class="section abstract"><div class="htmlview paragraph">The main indicators for mobility of a multipurpose wheeled vehicle are the maximum and average technical velocity (it is defined as the distance traveled divided by the time elapsed), and they are mainly determined by power-to-weight ratio and the parameters of the suspension. As our analysis shows, with the increase of the power-toweight ratio of the vehicle and its weight, the growth rate of the velocity is reduced, and after reaching a certain value, the velocity remains almost constant. This is due to the fact that for operating conditions of the multi-purpose wheeled vehicle, movement on roads with different degrees of uneven distribution of the rolling resistance and adhesion, in both transverse and longitudinal directions, is typical.</div><div class="htmlview paragraph">In this investigation we evaluate the effectiveness of the main methods of power distribution between the drive wheels of the multipurpose wheeled vehicles: disabling of drive axles, blocking of cross-axle and inter-axle differentials, a slowdown of slipping wheels.</div><div class="htmlview paragraph">It was revealed that the transmission of a promising multipurpose wheeled vehicle has to be modernized in the following ways: 1) all-wheel drive with the rational value of the gear ratio of inter-axle differential; 2) realization of the possibility of periodic shutdown of the drive axles when road conditions are good, or turning on the additional driving axles of the trailer when the road conditions require significant drive forces and torques; 3) providing of limited excess capacity of power unit by reducing the fuel supply or applying braking torque to the slipping wheels; 4) providing of rigid kinematic connection in the movement process with compensation of the kinematic mismatch by adjusting of air pressure in the tires.</div><div class="htmlview paragraph">At present, the effectiveness of the proposed methods of power distribution has been investigated in different extent. Thus, there arises the problem of the complex evaluation of the effectiveness of methods of the power distribution between the drive wheels of the multi-purpose wheeled vehicle. This investigation is devoted to this problem.</div></div>

<div class="section abstract"><div class="htmlview paragraph">This paper introduces a new concept for the identification of automatic transmission gear trains. It describes the use of kinematic graphs to separate the topological structure of the gear train from its function. Using this method, it has been shown that known epicyclic automatic transmission gear trains can be classified in a systematic and unbiased manner. This procedure allows transmission mechanisms which have different gear arrangements to be compared on a uniform basis so their similarities and differences can be identified.</div><div class="htmlview paragraph">It has been shown previously that there are 80 non-isomorphic displacement graphs from which all of the six-link, one-degree-of-freedom gear trains can be constructed. Here we show that there are seven non-isomorphic displacement graphs from which all epicyclic-type automatic transmission gear trains with up to six links and with four or more coaxial links can be derived.</div><div class="htmlview paragraph">In this paper, epicyclic-type transmission gear trains were searched, and their corresponding schematic and graph representations were classified. We found that the known transmission gear trains with six links all belong to these seven displacement graphs.</div></div>

<div class="htmlview paragraph">Shift quality in automatic transmissions is greatly affected by deterioration and variation of engine torque, hydraulic pressure control valves, friction elements and other factors. This paper presents a new control system that improves shift quality by using a turbine speed sensor to monitor the shift duration, particularly the duration of the inertia phase.</div> <div class="htmlview paragraph">The use of feedback control to vary the line pressure according to the shift duration makes it possible to eliminate the effects of aging and component variability. Other factors affecting shift quality, such as atmospheric pressure, road gradient and additional engine load from the air conditioner and alternator, were also examined, and it was found that their effects can be virtually eliminated through feedback control. The inertia phase usually becomes shorter as the engaging clutch capacity increases. However, an extremely small torque capacity can cause a short inertia phase, resulting in a large torque disturbance. This problem is avoided by measuring the interval from the initiation of the shift command to the completion of the inertia phase, this making it possible to distinguish between small and large torque capacity conditions.</div> <div class="htmlview paragraph">Power-off upshifts, resulting from abrupt throttle closing, can cause shock and chatter. These disturbances are eliminated through synchronized clutch engagement, achieved by sensing the speed ratio between the turbine and output shaft.</div> <div class="htmlview paragraph">Power-on downshifts when going downhill pose a critical condition for clutch slip. Friction elements are protected from damage in this system by controlling the timing and capacity of the engaging and releasing elements.</div>

<div class="htmlview paragraph"><b>THE author gives results of several years' experience in the development of automatic transmissions. Early designs are shown and explained and reasons for changes to present designs are given.</b></div> <div class="htmlview paragraph"><b>Driver reaction to different types of automatic shifting is discussed and conclusions are drawn.</b></div> <div class="htmlview paragraph"><b>Graphs are presented showing the acceleration characteristics of different jobs.</b></div> <div class="htmlview paragraph"><b>A detailed description of the author's latest development in fully automatic transmissions is given.</b></div>