Browse Topic: Automatic transmissions
ABSTRACT The following paper describes the new SAPA automatic transmissions for the future military vehicles. The very high mobility requirements, the reclaim of weight, power & space and the actual relevance of the fuel consumption require a rethinking and a new vision of the automatic transmission concept and design. This is what SAPA has been working on for the last 12 years obtaining excellent technical and commercial results, a concept aimed at reducing the power losses of the conventional powershifting transmission eliminating the torque converter, reducing the spin losses -due to hydraulic pumps and friction discs-, and improving vehicle mobility on variable terrain situations as off-road
The definitions and illustrations in this SAE Recommended Practice are intended to establish common nomenclature and terminology for automotive transmission one-way clutches
The 2025 Kia Carnival MPV is acquiring a hybrid powertrain as part of the minivan's model year update that debuted at the Chicago Auto Show. The internal-combustion engine option remains the 3.5-L V6 GDI seen in the current Carnival and produces 287 hp and 260 lb-ft (353 Nm) that powers the front wheels through an 8-speed automatic transmission. Engine power is down slightly from the output of the V6 in the 2024 model (290 hp and 262 lb-ft [355 Nm]). It's the addition of an electric motor to the new hybrid model where things get interesting. The hybrid Carnival uses a 1.6-L turbocharged 4-cyl. and a 54 kW motor that produce a combined 242 hp and 271 lb-ft (367 Nm). The Carnival Hybrid MPV uses a 6-speed automatic transmission. Improved fuel economy is one reason for the new hybrid option. While Kia doesn't yet have official EPA estimates, a spokesperson told SAE Media that the target is 32 mpg combined. The current ICE-only Carnival gets 22 mpg
This SAE Information Report details some of the equipment and procedures used to measure critical characteristics of automatic transmission fluid (ATF) used in current automatic transmissions. It is intended to assist those concerned with the design of transmission components, and with the selection and marketing of ATFs for the use in passenger car and light-duty truck automatic transmissions. The information contained herein will be helpful in understanding the terms related to properties, designations, and service applications of ATFs
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. The SAE No. 2 friction test is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluid combinations. The specific purpose of this document is to define a µPVT test for the evaluation of the variation of wet friction system low speed slip characteristics as a function of speed, temperature, and pressure. This procedure is intended as a suggested method for both suppliers and end users. The only variables selected by the supplier or user of the friction system are: Friction material Fluid Reaction plates Oil flow (optional) These four 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
Figures 1 through 6 illustrate in simplified form some of the more common planetary gears, gearsets, and geartrain arrangements in order to establish applicable terminology. Figures 7 and 8 provide additional examples that use elements of those gear arrangements
After three years away from the U.S. market with its range-topping SUV, the Land Cruiser, Toyota unveiled the redesigned 2024 Land Cruiser in Salt Lake City on Aug. 1. The model, long known around the world for its durability and offroad credentials, arrives with the SUV competition hotter than ever. The company said the new model will start at around $55,000. The new Land Cruiser has just one engine option, the i-Force Max turbo 2.4-L four-cylinder hybrid that generates 326 hp and 465 lb-ft (630 Nm) that is routed through an 8-speed automatic transmission. All models are equipped with what Toyota classifies as a “full-time four-wheel-drive system” with a lockable center differential and an electronically controlled 2-speed transfer case to impart high- and low-range capability. Also standard is a lockable rear differential to apportion power in a 50/50 ratio across the rear axle
The following is a list of the most common terminology used in describing automatic transmission functions
The range of test conditions on the dynamometer shall be sufficient to determine the primary operating characteristics corresponding to the full range of vehicle operations. The characteristics to be determined are: a Torque ratio versus speed ratio and output speed b Input speed versus speed ratio and output speed c Efficiency versus speed ratio and output speed d Capacity factor versus speed ratio and output speed e Input torque versus input speed NOTE: For more information about these characteristics and the design of hydrodynamic drives, refer to “Design Practices: Passenger Car Automatic Transmissions,” SAE Advances in Engineering, AE-18 (Third Ed.) or AE-29 (Fourth Ed
This SAE Standard incorporates driving cycles that produce fuel consumption data relating to Urban, Suburban, and Interstate driving patterns and is intended to be used to determine the relative fuel economy among vehicles and driving patterns under warmed-up conditions on test tracks, suitable roads, or chassis dynamometers.1
Over the past couple of years, Argonne National Laboratory has tested, analyzed, and validated automobile models for the light duty vehicle class, including several types of powertrains including conventional, hybrid electric, plug-in hybrid electric and battery electric vehicles. Argonne’s previous works focused on the light duty vehicle models, but no work has been done on medium and heavy-duty vehicles. This study focuses on the validation of shifting control in advanced automatic transmission technologies for medium duty vehicles by using Argonne’s model-based high-fidelity, forward-looking, vehicle simulation tool, Autonomie. Different medium duty vehicles, from Argonne’s own fleet, including the Ram 2500, Ford F-250 and Ford F-350, were tested with the equipment for OBD (on-board diagnostics) signal data record. For the medium duty vehicles, a workflow process was used to import test data. In addition to importing measured test signals into the Autonomie environment, the process
This paper describes a new control technology that coordinates the operation of multiple actuators in a new hybrid electric vehicle (HEV) system consisting of a turbocharged engine, front and rear electric motors, two clutches, and a 6-speed automatic transmission. The development concept for this control technology is to achieve the driver’s desired acceleration G with a natural feeling engine speed. First, to realize linear acceleration G even while the engine is starting from EV mode, clutch hydraulic pressure reduction control is implemented. Furthermore, the engine start timing is optimized to prevent delayed drive force response by predicting the required maximum power during cranking. Second, to realize linear acceleration, this control selects the proper gear position based on the available battery power, considering noise and vibration (NV) restrictions and turbocharging response delays. Finally, to precisely control engine speed when the clutch is not directly connected
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
This document describes a set of recommended actions to take to increase the likelihood of safe vehicle operation when a device (external test equipment, data collection device, etc.) whose normal operation has been compromised by a source external to the vehicle is connected to the vehicle’s diagnostic system. The term “diagnostic system” is intended to be a generic way to reference all the different ways that diagnostic commands might be injected into the system. The guidance in this document is intended to improve security without significantly impacting the ability for franchised dealer or independent aftermarket external test tools to perform legitimate diagnosis and maintenance functions. The goal is that intrusive services are only allowed to be performed when the vehicle is in a Safe State such that even if the intrusive service were to be initiated with adversarial intent the consequences of such a service would still be acceptable
This research aims to model and assess autonomous vehicle controller while including a four-wheel steering and longitudinal speed control. Such a modeling process simulates human driver behavior with consideration of real vehicle dynamics’ characteristics during standard maneuvers. However, a four-wheel steering control improves vehicle stability and maneuverability as well. A three-degree of freedom bicycle model, lateral deviation, yaw angle, and longitudinal speed is constructed to describe vehicle dynamics’ behavior. Moreover, a comprehensive traction model is implemented which includes an engine, automatic transmission, and non-linear magic formula tire model for simulation of vehicle longitudinal dynamics. A combination of proportional integral derivative (PID) longitudinal controller and fuzzy lateral controller are implemented simultaneously to track the desired vehicle path while minimizing lateral deviation and yaw angle errors. Then, A linear quadratic regulator (LQR) based
Traditionally, the controls system in production vehicles with automatic transmission interprets the driver’s accelerator pedal position as a demand for transmission input torque. However, with the advent of electrified vehicles, where actuators are located at different positions in the drivetrain, and of autonomous vehicles, which are self-driving, it is more convenient to interpret the demand (either human or virtual) in vehicle acceleration or wheel torque domain. To this end, a Wheel Torque-based longitudinal Control (WTC) framework was developed, wherein demands can be converted accurately between the vehicle acceleration or wheel torque domain and the transmission assembly input torque domain. For powertrains with a step-ratio transmission and a torque converter (TC), a key challenge of this conversion is the determination of the Inertia Compensation Torque (ICT), which is the torque required to accelerate or decelerate the TC’s impeller when the TC operates in the slipping or
A Torque converter is a type of hydro-mechanical device, vastly utilized in the automatic transmission of vehicles and other machines. It is a critical component of the transmission system, having a direct impact on the fuel economy and vehicle´s performance. Computational Fluid Dynamics (CFD) has been employed by many authors and engineers to better understand the complex behavior of fluids inside of torque converters, in a way that it provides design improvements and increases model accuracy. This article presents a methodology that applies CFD as a tool in the design process of automobile torque converters. Therefore, this paper performs an extensive review of CFD associated with torque converters, and the principal concepts are stated and used to have a better understanding of the system’s dynamic behavior. Additionally, this article details some of the work done to develop an automotive torque converter model using the commercial software ANSYS CFX
We present our approach to several control challenges in high-speed autonomous racing for the Indy Autonomous Challenge (IAC). The IAC involves autonomous head-to-head racing at speeds approaching 200 mph. The autonomy system must maintain traction and stability when operating at such high speeds while also maneuvering aggressively around other competitor vehicles. One key challenge arises from limited actuator update frequency. We propose two lateral control methods to follow the desired trajectory: a cross-track error method and a pure pursuit lookahead angle method. Analysis shows that, when linearized, cross-track error and pure pursuit angle are related by a first-order system. To analyze the effect of actuator update frequency on closed-loop performance, we emulate the discrete rate as a time delay. Control parameters and gains for both controllers can be solved by using loop-shaping techniques to guarantee closed-loop bandwidth and phase margin. The bandwidth is limited by the
Taking an off-road vehicle equipped with 32-speed binary logic automatic transmission (AT) as the research object, the slope starting control research is carried out. The slope starting process is divided into the overcoming resistance stage, the sliding friction stage, and the synchronization stage. The control strategies for each stage are designed respectively. Focusing on the control of the sliding friction stage, the equivalent two-speed model of the starting clutch is established, which realizes the calculation of the speed difference and the slip rate between the driving and driven ends of the starting clutch. Furthermore, the slope starting control strategy based on the proportional-integral-derivative (PID) control of the clutch slip rate is designed. Through the simulation tests of the vehicle starting at different slopes, the correctness of the slope starting control strategy has been verified by MATLAB/Simulink. The strategy proposed in this paper shortens the slope
This SAE Recommended Practice establishes the test procedure, environment, and instrumentation to be used for measuring the exterior exhaust sound level for passenger cars, multipurpose vehicles, and light trucks under stationary conditions providing a continuous measure of exhaust system sound level over a range of engine speeds. This document applies only to road vehicles equipped with an internal combustion engine. The method is designed to meet the requirements of simplicity as far as they are consistent with reproducibility of results under the operating conditions of the vehicle. It is within the scope of this document to measure the stationary A-weighted sound pressure level during: Measurements at the manufacturing stage Measurements at official testing stations Measurements at roadside testing It does neither specify a method to check the exhaust sound pressure level when the engine is operated at realistic load nor a method to check the exhaust sound pressure levels against a
During the vehicle launch (i.e. moving the vehicle from “0” speed), the clutch would be slowly engaged by the Driver or Transmission Control Unit (in Automatic Transmission/Automatic Manual Transmission vehicle) for smooth torque transfer between engine and transmission. The clutch is designed to transfer max engine torque with min heat generation. During the clutch engagement, the difference in flywheel and gearbox input shaft speed is called the clutch slipping phase which then leads to a huge amount of energy being dissipated in terms heat due to friction. As a result, clutch surface temperature increases consistently, when the surface temperature crosses the threshold limit, the clutch wears out quickly or burns spontaneously. Hence it is crucial to predict the energy dissipation and temperature variation in various components of clutch assembly through virtual simulation. During the development process of the vehicle, the clutch is tested over many duty cycles to ensure the
This paper investigates the application of torque weighting to vibration dose value. This is done as a means to enhance correlation of perceived drive comfort directly to driver pedal commands while rejecting uncorrelated inputs. Current industry standards for vehicle comfort are formulated and described by ISO2631, which is a culmination of research with single or multi-axis vibration of narrow or broadband excitation. The standard is capable of estimating passenger comfort to vibrations, however, it only accounts for reaction vibrations to controlled inputs and not perceived vibration request vs. response vibration. Metrics that account for torque inputs and the vibration response create actionable estimates of dosage due to driver torque requests without uncorrelated inputs. This reduces the need for additional accelerometers and special compensating algorithms when road or track testing. The use case for the proposed modified metric is during the powertrain calibration process
This test procedure is intended to apply to hydraulic pump suction filters and strainers used in automotive automatic transmissions that include hydraulic power pumps. The various paragraphs of Section 5 include a variety of tests and alternative tests that are not applicable to all filters and applications, so the engineer must specify which tests are to be performed for a particular application. These test procedures are intended to evaluate filter functional performance characteristics only, durability is not evaluated under this standard. Filter design requirements must be specified by the engineer on the filter assembly drawing, an applicable engineering specification, or summarized on an application data sheet similar to that found in this recommended practice. See Figure 6. Pressure circuit filters, both barrier and system contamination control types, are not covered under this standard. They are similar in design and construction to filters used in many hydraulic and
This SAE Standard covers hose intended for use with automatic transmission cooling system applications. Type A hoses are intended for original equipment or replacement applications while Type B hoses are intended for aftermarket auxiliary cooler applications only. The reference fluid for tests requiring the use of automatic transmission fluid (ATF) shall be Dexron III / Mercon 5 or equivalent ATF that is agreed to by hose manufacturer and customer
This SAE Recommended Practice describes the recommended methods for testing flexible harness coverings for use on ground vehicle electrical distribution systems. This SAE Recommended Practice shall apply to all tapes, extruded tube, and textile tube
Model-guided development of drivetrain control and calibration is a key enabler of robust and efficient vehicle design process. A number of CAE tools are available today for modeling hydro-mechanical systems. Automatic transmission behaviors are well understood to effectively tune the model parameters for targeted applications. Drivetrain models provide physical insight for understanding the effects of component interactions on system behaviors. They are also widely used in HIL/SIL environments to debug control strategies. Nonetheless, it is still a challenge to predict shift quality, especially during a sequence of multiple events, with enough accuracy to support model-guided control design and calibration. The inclusion of hydraulic circuits in simulation models often results in challenges for numerical simulation. The complex interaction of component behaviors can make it difficult to tune a large number of model parameters in a manner consistent with an engineer’s intuition
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