AUTOMATIC TRANSMISSIONS. COMPLEX OF ALGORITHMS OF “CLUTCH-TO-CLUTCH SHIFTS” TECHNOLOGY: ANALYSIS OF ARCHITECTURE, GENERALIZED STRUCTURE, DEVELOPMENT. PART 2

The article continues the series of the author publications, which considers the main provisions of the “Clutch-to-Clutch Shifts” (CTC) technology — technology for automatic controlling the switching of automatic transmission (AT) stages, used in the global mass production of vehicles, hybrid and battery electric vehicles. It provides high-quality shifts, brought to the level of continuously variable transmissions. Development of power units in recent years has led to a rapid increase in the number of AT stages, which is accompanied by a complication of kinematic schemes, designs, control algorithms and, in general, an increase in the role of mechatronic control systems (MCS) in ensuring their high technical level. Effectiveness of the CTC technology depends on the perfection of the algorithms used. But their composition is not specified, which, with a large amount of information, makes it difficult for potential users to navigate in this set. In this paper, we propose (for the first time in the Russian language) the generalized structure of a set of standard algorithms necessary for the implementation of this technology in the AT MCS, which is developed on the basis of their selection from a pre-formed database of patents and publications on the theory and technology of AT control, following classification and grouping by functional purpose. For each item of the structure, there are links to patents with matching names. Detailed descriptions of several typical CTC algorithms in the AT MCS of General Motors patents are given.

AUTOMATIC TRANSMISSIONS. COMPLEX OF ALGORITHMS OF “CLUTCH-TO-CLUTCH SHIFTS” TECHNOLOGY: ANALYSIS OF ARCHITECTURE, GENERALIZED STRUCTURE, DEVELOPMENT. PART 1

The article continues the series of the author publications, which considers the main provisions of the “Clutch-to-Clutch Shifts” (CTC) technology — technology for automatic controlling the switching of automatic transmission (AT) stages, used in the global mass production of vehicles, hybrid and battery electric vehicles. It provides high-quality shifts, brought to the level of continuously variable transmissions. Development of power units in recent years has led to a rapid increase in the number of AT stages, which is accompanied by a complication of kinematic schemes, designs, control algorithms and, in general, an increase in the role of mechatronic control systems (MCS) in ensuring their high technical level. Effectiveness of the CTC technology depends on the perfection of the algorithms used. But their composition is not specified, which, with a large amount of information, makes it difficult for potential users to navigate in this set. In this paper, we propose (for the first time in the Russian language) the generalized structure of a set of standard algorithms necessary for the implementation of this technology in the AT MCS, which is developed on the basis of their selection from a pre-formed database of patents and publications on the theory and technology of AT control, following classification and grouping by functional purpose. For each item of the structure, there are links to patents with matching names. Detailed descriptions of several typical CTC algorithms in the AT MCS of General Motors patents are given.

On the Design of Continuously Variable Transmissions with Bidirectional Bridge Structures for Hybrid Vehicles

To increase the energy efficiency of road vehicles, an ideal transmission system should have a wide ratio coverage, a high torque capacity, and a high mechanical efficiency. Continuously variable units (CVUs) have been successfully implemented due to the smooth ratio variation, sufficient torque capacity, and ratio coverage. Hence, it will be beneficial to develop a hybrid powertrain comprising a CVU. In this paper, a design method called the “basic path diagram” (BPD) is proposed. It provides a simplified schematic of the system and represents the generic connections among the mechanical components. The system configurations synthesized by the BPD can be sorted according to three characteristics: Direction of power flows through the CVU, coupling pattern of the power inputs, and number of transmission paths parallel to the CVU. The first characteristic determines the number of times the CVU ratio coverage can be exploited, the second characteristic determines whether the torque of the power inputs can be independently controlled, and the third characteristic can help reduce the torque loading of the CVU. With the aid of a BPD, one of the possible system configurations is provided as an example. The result shows that the system can exploit twice the ratio coverage of the CVU and reduce the torque and power transmitted by the CVU in combination with planetary gearsets.

Introduction of a redundant actuator using planetary gear trains for human centred robotics

Matching motor efficiency and performance with the load demands can significantly improve the overall efficiency of a driveline. Inspired by the automotive sector -with the high interest of hybrid and electric cars currently-, the authors have studied how state of the art technologies can be used in the relatively new field of collaborative and Human centred robotics. Multiple transmission systems have been considered, among others redundant actuators (both static and kinematic) and continuously variable transmissions. Based on these findings and the experience of the research group on customised planetary gear trains for Human Limb Assistance and Replication, an extensive review of existing redundant actuators is presented in combination with an alternative transmission system which does not need any auxiliary gear transmissions and hence can be lighter and more compact than state of the art drivelines for Human centred robotics. A calculation was performed -including the efficiency model presented by Müller- which shows the high potential of this type of dual-motor actuator.

Preliminary synthesis of algorithms for automatic control of automobile continuously variable transmissions with flexible links

Variators of different operating principles and designs are of interest as components of automatic transmissions for ground transport and traction machines. At the same time, one of the most popular types of variators are the variators built on the basis of continuously variable transmissions with flexible links. The main reasons for the use of such variators in the transmissions of a number of modern passenger vehicles are, on the one hand, the emergence of flexible link designs with high durability, and, on the other hand, the widespread introduction of programmable electronic devices into automatic control systems for continuously variable transmissions. A direct consequence of the latter circumstance was the need for in-depth research aimed at synthesizing such control algorithms that would make it possible to fully use the advantages inherent in continuously variable transmissions with flexible links and minimize the operational consequences of their shortcomings. This paper makes an attempt to solve the problem of synthesizing the algorithm in a preliminary form, based on the goal of providing the vehicle with the best traction and speed properties. The presence of such an attempt will allow, having set the main parameters of a continuously variable transmission for some reason, to develop the hardware of the automatic control system. In turn, this will make it possible to synthesize a refined algorithm that takes into account the dynamics of the system, errors of meters and signal conversion devices, as well as other factors affecting work pro-cesses. When considering the described problem, various variants of the geometry of the contact surfaces of the continuously variable transmission links were taken into account and the corre-sponding mathematical apparatus were formed. The results of calculations, obtained by computer program that implements these devices, are selectively presented in the materials of the paper.

Investigation technique for dynamics of operative mechanical continuously variable transmission with a resilient member and free-wheel mechanism

Mechanical continuously variable transmissions have high potential for torque conversion, are capable of providing significant technical and economic advantages when used in shafts of technological and other machines, this making investigations in this area to be pertinent. This paper represents a mechanical and mathematical technique, which enables to do research of dynamic processes, that occur in functioning of mechanical continuously variable transmission with a resilient member and free-wheel mechanism, making it possible to transmit torque to a driven shaft only in the same direction. The objective of this paper is to work out a mathematical model of the mechanical system, which determines dynamic force of transmission elements. Computational model of transmission is shown, in obedience to which there was built a mathematical model based on Lagrange equation of second kind with undetermined multipliers. A set of assumptions was made on working out the dynamic system mathematical model. In particular, possibility of excitation of resonant modes in a resilient member was not considered. Moreover, nonlinearity of free-wheel mechanisms was not considered as well as hysteresis losses of energy in on-off use cycle and significant capacity costs in disconnected machinery. In future it is necessary to carry out experimental investigations in order to make transmission dynamics more exact. By the results of simulation modeling regularities were obtained which determine dynamic moments on transmission elements. The results of the investigation may be used for making an output characteristic of transmission, its adaptation with the motor and forecasting of operational features of shafts of different technological equipment.

Formal Process to Support Resolution of Functional Trade-Offs in Complex Product Development

This research study proposes a method to resolve issues with trade-offs between functionalities, which hinder the unconventional improvement of a product. As products have become increasingly complex, it has become difficult to grasp all the aspects of a product. To resolve the problematic trade-off issues of a complex product, it is necessary to model the product in an appropriate form and to gather knowledge from experts in each domain. Although there have been several models to tackle this issue, modeling still poses difficulties due to a lack of clear guidelines. This paper classifies models into three types: function-based, cognition-based, and physics-based models. Next, their roles and description guidelines are clarified. As a function-based model depicts the functionality of a product in a rather simple description, it is employed to specify significant trade-offs. A cognition-based model depicts the designers' recognition of physical phenomena, whereas a physics-based model rigorously depicts the physical phenomena. A cognition-based model is appropriate for ideation, while the physics-based model contributes to the objectivity of a model. This study proposes a strategy of complementary modeling and the use of cognition-and physics-based models. To support the ideation of a solution to the trade-offs, the theory of inventive problem solving (TRIZ) is applied. The proposed method is validated by a case study of continuously variable transmissions (CVT).

A Positively-Engaged Infinitely Variable Transmission Using Split Helical Gears

Continuously variable transmissions (CVTs), and the subset known as infinitely variable transmissions (IVTs) with gear ratio ranges reaching zero (0:1 or 1:∞ or “geared neutral”), offer motors the ability to run in preferred angular velocity ranges independent of transmission output speed, allowing optimization for power, torque, and efficiency. This paper presents and analyzes a positively engaged IVT (PE-IVT) mechanism of an entirely new type and working principle which solves the problems of current CVTs and is applicable to the unique requirements of robots, electric vehicles (EVs), and hybridelectric vehicles (HEVs).