Browse Topic: Hydromechanical transmissions
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
Since the torque converter and fluid coupling are commonly used components of automatic transmissions in industry, the SAE appointed a committee to standardize terminology, test procedure, data recording, design symbols, and so forth, in this field. The following committee recommendations will facilitate a clear understanding for engineering discussions, comparisons, and the preparation of technical papers. The recommended usages represent the predominant practice or the acceptable practice. Where agreement is not complete, alternates have been included for clarification. EXAMPLE: Two systems of blade angle designations are described. Consequently, when a blade angle is specified, the system should be designated. This SAE Recommended Practice deals only with the physical parts and dimensions and does not attempt to standardize the design considerations, such as the actual fluid flow angle resulting from the physical blade shape
To provide a means of obtaining the efficiency characteristics of automatic transmissions and automatic transaxles. It outlines dynamometer tests that map the steady-state characteristics over a range of operations of an automatic transmission/automatic transaxle and provides a method of presenting test data. This procedure must be followed, with similar test facilities so that results obtained from different laboratories are comparable. For this SAE Recommended Practice, the transmission is defined as the complete automatic transmission or transaxle assembly between the engine and the driveshaft(s) used to effect a ratio change in transmitting power. For 4WD/AWD, it does not include transfer case or power take off subsystems. This test procedure deals with the aspect of conducting complete transmission and transaxle assembly testing. However, by its very nature a transmission should be viewed as a compilation of three major component systems: pump, torque converter, and gearbox (all
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, see “Design Practices—Passenger Car Automatic Transmissions,” SAE Advances in Engineering, Vol. 5
To measure the performance characteristics of Continuously Variable Transmissions (CVT). It outlines dynamometer tests that cover the range of operation and provides a method of presenting the test data. This procedure must be followed with similar test facilities so that results obtained from different laboratories are comparable
The following system of symbols is recommended for use in technical papers and engineering reports dealing with hydrodynamic drives
Since the torque converter and fluid coupling have become commonly used components of automatic transmissions in industry, the SAE appointed a committee to standardize terminology, test procedure, data recording, design symbols, and so forth, in this field. The following committee recommendations will facilitate a clear understanding for engineering discussions, comparisons, and the preparation of technical papers. The recommended usages represent the predominant practice or the acceptable practice. Where agreement is not complete, alternates have been included for clarification. This SAE Recommended Practice deals only with the physical parts and dimensions and does not attempt to standardize the design considerations, such as the actual fluid flow angle resulting from the physical blade shape
The following schematic diagrams exemplify the SAE recommended method of illustrating automotive transmission arrangements. They were developed to standardize industry practice and facilitate a clear understanding of the functional interrelations of the gearing, clutches, hydrodynamic drive unit, and other transmission components. Two variations of diagrams are used: transmission in neutral and in gear. For illustrative purposes, some typical transmissions are shown
To provide a means of obtaining the performance characteristics of automatic transmissions and automatic transaxles. It outlines dynamometer tests that map the steady-state characteristics over a range of operations of an automatic transmission/automatic transaxle and provides a method of presenting test data. This procedure must be followed, with similar test facilities so that results obtained from different laboratories are comparable. For this SAE Recommended Practice, the transmission is defined as the complete automatic transmission or transaxle assembly between the engine and the driveshaft(s) used to effect a ratio change in transmitting power. This test procedure deals with the aspect of conducting complete transmission and transaxle assembly testing. However, by its very nature a transmission should be viewed as a compilation of three major component systems: pump, torque converter, and gearbox (all ratio change elements). From a design perspective, it is important that the
The following schematic diagrams exemplify the SAE recommended method of illustrating automotive transmission arrangements. They were developed to standardize industry practice and facilitate a clear understanding of the functional interrelations of the gearing, clutches, hydrodynamic drive unit, and other transmission components. Two variations of diagrams are used: Transmission in neutral and in gear. For illustrative purposes, some typical transmissions are shown
To provide a means of comparing the performance characteristics of automatic transmissions. It outlines dynamometer tests that cover the range of operation of transmissions and provides a method of presenting the test data. This procedure must be followed with similar test facilities so that results obtained from different laboratories are comparable. For this SAE Recommended Practice, the transmission is defined as the complete assembly driven by the engine and used to effect a ratio change in transmitting power to the final drive system
The following schematic diagrams exemplify the SAE recommended method of illustrating automotive transmission arrangements. They were developed to standardize industry practice and facilitate a clear understanding of the functional interrelations of the gearing, clutches, hydrodynamic drive unit, and other transmission components. Two variations of diagrams are used: Transmission in neutral and in gear. For illustrative purposes, some typical transmissions are shown
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, see "Design Practices--Passenger Car Automatic Transmissions," SAE Advances in Engineering, Vol. 5
The following system of symbols is recommended for use in technical papers and engineering reports dealing with hydrodynamic drives
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 transmission characteristics to be determined for all driving ranges or gears are: 1 Efficiency versus output speed. 2 Torque ratio versus output speed. 3 Input speed versus output speed. 4 Output torque versus output speed. 5 Parasitic losses versus input speed
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: 1 Torque ratio versus speed ratio and output speed. 2 Input speed versus speed ratio and output speed. 3 Efficiency versus speed ratio and output speed. 4 Capacity factor versus speed ratio and output speed. 5 Input torque versus input speed. Note: For more information about these characteristics and the design of hydrodynamic drives, see “Design Practices-Passenger Car Automatic Transmissions,” SAE Advances in Engineering, Vol. 5
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