Scheme Design and Optimal Selection for HEV Planetary Gear Coupling Mechanism

Taking a hybrid electric vehicle using double-row planetary gear power coupling mechanism as a research object, this study proposes a coordinated control algorithm of “torque distribution, engine torque monitoring, and motor torque compensation” in an attempt to realize coordinated control for driving mode switching. Characteristic analysis of the power coupling mechanism was carried out, and the control strategy model in MATLAB/Simulink was built. Subsequently, the analysis of mode switching from the electric mode into joint driving mode was simulated. In addition, a multibody dynamics model of the power coupling mechanism was established and the simulation analysis during mode switching process was carried out. The results show that the proposed coordinated control strategy serves to effectively reduce the torque fluctuation and the impact degree during the mode switching process and improve the ride comfort of the vehicle. In the meantime, the time-domain and frequency-domain characteristics of gear meshing force and bearing restraint force indicate that the mode switching process of the dynamic coupling mechanism is quite stable and this control strategy contributes to improving the characteristics such as vibration and noise.

According to the characteristic formula of planetary gear transmission, by studying the movement and torque transmission of planetary gear mechanism of Automatic Transmission, this paper presents a new method of transmission analysis by use of the matrix. The method established the mathematical model about the coupling form and shift constraint and torque transmission between the planetary lines based on matrix theory. It is generally applicable to the movement and torque calculation of complex planetary gear mechanism.

<div class="htmlview paragraph">A new point of view in automatic transmission is proposed by R-R chart, which is a new analytic method based on the linearity of planetary gear and gear shift mechanism. The R-R chart is a visual tool to describe the whole motion of each rotational element of planetary gears in relation to the gear shift mechanism. Therefore, anyone can easily find on R-R chart not only the substance of the gear shift mechanisms in present automatic transmissions but also new gear shift mechanisms for the future automatic transmissions. This paper shows that the R-R chart is unique in 4-speed automatic transmissions with fixed compound planetary gear sets. As a result of the R-R chart application, this paper classifies the fixed compound planetary gear sets with 4 elements into 12 sets and the gear shift mechanisms into 3 types. Also, 4 R-R characteristic equations are derived as a correlation between speed ratios in 4-speed automatic transmissions. This paper describes systematically the gear shift mechanisms for 5- and 6-speed automatic transmission by R-R chart. Finally, this paper introduces the new gear shift mechanism for 5-speed automatic transmission with 3 clutches and 1 brake.</div>

This paper presents a comprehensive study on the structural synthesis and classification of planetary gear mechanisms (PGCMs), which combine the advantages of planetary gear trains (PGTs) and cam mechanisms to produce precise, intermittent, or variable-speed motions. These mechanisms are particularly suitable for high-performance industrial applications, such as indexing tables, path generation systems, and rigid body guidance. The work begins by detailing the kinematic and structural characteristics of PGCMs and identifying possible configurations based on degrees of freedom, link types, and joint arrangements. Using graph theory, rooted graph representations are developed to systematically enumerate two-degree-of-freedom PGCMs, up to seven links. A spanning-tree-based synthesis method is used to generate candidate structures, followed by genetic compatibility analysis to identify viable PGCM configurations. The proposed method produces a set of functionally and structurally distinct PGCMs, including a novel five-link mechanism that achieves precise path generation with minimal complexity. This study not only enhances the theoretical framework for PGCM design, but also provides a practical basis for its application in modern mechanical systems.

To obtain the optimal seedling taking trajectory, this study proposed the adjustment of the total transmission ratio curve by using human-computer interaction. On the basis of this design method, a planetary non-circular gear mechanism was designed that can realize the twice unequal amplitude transmission ratio to meet the seedling harvesting requirements. The cubic non-uniform B-spline curve was used to fit the twice unequal amplitude transmission ratio curve, and the transmission ratio was freely distributed in two levels. The seedling pick-up mechanism was designed by controlling the seedling taking track and the corresponding attitude directly through the local section of the total transmission ratio, and the gear pitch curve was directly controlled by the transmission ratio. The kinematics model of the seedling pick-up mechanism was also established. Furthermore, the influence of the total transmission ratio on the seedling picking track, the ratio of the wave crest to the amplitude, and the mechanism parameters were discussed. A human-computer interactive optimization software was developed using Matlab, and a set of optimal parameters for the seedling pick-up mechanism was obtained to meet the transplanting requirements. By using the Adams software, the virtual prototype simulation of the seedling pick-up mechanism was completed, and the idle experiment for the track and attitude of the prototype was conducted through high-speed camera technology. The theoretical, simulated, and experimental trajectories were consistent with each other. Results revealed that the success rate of the seedling picking exceeded 90% when the rotation speeds were 40 r/min, 50 r/min, and 60 r/min, and the qualified rate of the matrix decreased with the increase in rotating speed. Moreover, the number of damaged plants increased with the increase in rotating speed. The experimental results showed that the seedling pick-up mechanism designed using the proposed method demonstrated a good effect and met the required seedling picking performance. Keywords: seedling pick-up mechanism, second unequal amplitude, planetary gear train, seedling picking experiment DOI: 10.25165/j.ijabe.20221501.6168 Citation: Liu J G, Yu G H, Tong Z P, Hua Y. Design and experimental study of a planetary gearing mechanism based on twice unequal amplitude transmission ratio. Int J Agric & Biol Eng, 2022; 15(1): 155–163.

The current tendency of the development of wind power technology is that the variable wind turbines adjust the speed of wind rotor at real time in accordance with wind speed to absorb wind energy more effectively and improve the operating condition of power chain. A critical point of the design of variable wind turbines is to settle the influence of wind speed changes on the smooth electric power output and power driving chain. Based on the differential planet gear system, this paper gives a research on a kind of power splitting driving chain (PSDC), with the basic thought as follow: The wind rotor linked by planet gear frame axis functions as the main power input terminal; Both a main generator and an auxiliary one are adopted in the double degree of freedom planet gear mechanism; The main generator is driven by gear ring of the planet gear mechanism to realize most of energy conversion in the power driving chain and the electric-energy output to the power grid; the auxiliary generator linked by the sun gear serves as the servo element of PSDC. Meanwhile, the servomotor links the supply grid with bi-efficacy of generator and motor under the control of small electronic power devices, achieving the control of electromagnetic torque and the constant-speed operating function of main generator. The analysis in this paper shows that the large variable wind turbines consisting of this kind of power splitting driving chain (PSDC) could provide new solutions for those problems with which variable wind turbines are confronted, such as difficulties in the design and manufacture of special large generator, its extortionate cost, the high price of electronic power system for high power conversion and control, as well as the mutual influence between wind turbine unit and supply grid.

Synthesis of multi-mode electric-mechanical variable transmission (EVT) mainly involves two contents: the topology of planetary gear mechanism (PGM) and the determination of their characteristic parameters. This article deals with the computationally intensive problems caused by numerous potential schemes and proposes an automatic and systematic design process for multi-mode EVTs based on 3-row PGM. First, all the non-isomorphic 4-degree-of-freedom (4-DOF) topologies are enumerated by combining the modified digraph model with the determinants of their adjacency matrices. Second, the rules with guiding significance for configuring shift elements and motor/generators (M/Gs) are summarized to eliminate all infeasible configurations. And all the mechanical points (MPs) that come from the kinematic equations play an important role in the selection of new schemes. Third, the method of Monte Carlo simulation handles the problem of solving many different forms of multivariate nonlinear functions to sort the rational mode sequences. Finally, the characteristic parameters of each planetary gear set are optimized by NSGA-II. The feasibility of the method is verified by synthesizing six novelty 3-mode EVTs and it is also applicable to similar problems.

Many of today's power-split hybrid electric vehicles (HEVs) utilize planetary gears (PGs) to connect the powertrain elements together. Recent power-split HEVs tend to use two PGs and some of them have multiple modes to achieve better fuel economy and driving performance. Looking to the future, hybrid powertrain technologies must be enhanced to design hybrid light trucks. For light trucks, the need for multi-mode and more PGs is stronger, to achieve the required performance. To systematically explore all the possible designs of multi-mode HEVs with three PGs, an efficient searching and optimization methodology is proposed. All possible clutch topology and modes for one existing configuration that uses three PGs were exhaustively searched. The launching performance is first used to screen out designs that fail to satisfy the required launching performance. A near-optimal and computationally efficient energy management strategy was then employed to identify designs that achieve good fuel economy. The proposed design process successfully identify 8 designs that achieve better launching performance and better fuel economy, while using fewer number of clutches than the benchmark and a patented design.

Planet gear mechanism is designed according to the planet gear action during the course of screw cap after working principle of the cap screwing machine is briefly introduced. The course of screw cap can be simulated by the dynamics simulation software ADAMS. The relation between rotational speed and the gearing-in force can be obtained. This provides the theoretical foundation for the improvement of seal quality in cap screwing machine.

This paper proposes a cleaning machine using a planetary gear mechanism to remove accumulated grease within kitchen ducts of diverse geometries, encompassing circular and square configurations. The contributions of this paper encompass describing the brush and motor determination methods, detailing the development of the actual machine, and presenting the outcome of the cleaning experiment. The purpose of this study is to remove accumulated grease within ducts via a single robot, thereby preventing duct conflagrations. While duct cleaning is typically done manually, small, hard-to-access ducts have often been uncleaned. In this study, we developed a cleaning machine using a planetary gear mechanism capable of scrubbing off accumulated grease within small square ducts through a singular brushing operation. In the cleaning experiment, the proposed machine successfully removed over 30% of the accumulated grease within a small, difficult-to-access duct. Therefore, we expect that the proposed machine will make a significant contribution to the prevention of duct fires by scrubbing off grease from ducts that are typically difficult for people to access and have not been cleaned in the past.

This paper proposed a method of representing the geometry of an imaginary disc cutter in parameter form. The undercutting condition of the imaginary disc cutter is studied, and the mathematical model of the generated gears is developed by the undercutting condition of the cutter. Through a mathematical model of the generation process, the vector equations of generated gears are established. According to the proposed method, a planetary gear mechanism and a pair of gear pump with smaller numbers of teeth are illustrated. A cutting simulation process is presented for machining the proposed gear pairs. Stress analysis for the proposed gear mechanism is performed. Finally, the proposed method is applied to determine singular points of the proposed disc cutter.

This paper focuses on a simulation and analysis of a hybrid electric vehicle (HEV) with a double rotor motor (DRM) based on the ADVIOSR software. The DRM is a novel series-parallel HEV powertrain concept which realizes the power split function in an electromagnetic way rather than in a mechanical way with a planetary gear. In this paper, a simulation model of a HEV with a DRM is established through performing the redevelopment in ADVISOR. A dynamic simulation was performed to take into account different driving cycles. The model and simulation method are verified reasonable and feasible based on the simulation results (fuel economy, power performance). Compared with the simulation results of PRIUS model and parallel HEV model, the distinct advantage of the proposed HEV belonging to the DRM can be obviously found out.

Power-split hybrid electric vehicles (HEVs) utilize planetary gears (PGs) and a relatively small number of frictional elements, including clutch and brake, to connect the power sources together. Recently, power-split HEVs tend to use two PGs and have multiple modes to achieve better driving performance and fuel economy. Looking forward to the future, hybrid powertrain technologies must be enhanced to design hybrid heavy-duty vehicles. To meet the required performance of the heavy-duty vehicles, the need for multi-mode and more PGs is stronger. In this scenario, this paper proposed an electromechanical transmission (EMT) system with three PGs and three frictional elements to combine one engine and two motor-generators with the vehicle. The proposed EMT is explored and designed by a holistic approach, which includes system configuration and operational modes search, dynamic equations derivation and energy management design. Next, the analysis, verification and validation through simulation and comparison with the data actually measured in the bench test are carried out. The excellent agreements between the simulation and the experimental results demonstrate the fidelity and validity of the designed EMT-based power-split HEV model.

The paper presents two kinematic schemes of the reverse driving mechanism on CVT’s, the first one for rear-wheel drive, and the second one for front-wheel drive. For the first kinematic scheme, the reverse driving mechanism consists of a planetary cylindrical gear set and a multi-disk brake. In order to achieve a better efficiency for reverse driving, the authors propose a new kinematic structure of a planetary cylindrical gear mechanism, simpler than the existing designs. While describing a synthesis of the new kinematic solution, special attention was granted to maintaining the advantages of each of the two existing mechanisms, and highlighting the advantage of using less cylindrical gears.

In this paper, a simulator was built to simulate a plug-in hybrid electric vehicle (PHEV) power system. Specifically, a model adopting a series/parallel hybrid system with a planetary gear mechanism was created. With this model, the impacts of the engine on/off control and drive distance on environmental performance were analyzed using a homologation driving schedule for Japan. It was proven that when providing PHEVs to the market it will be necessary to adjust the engine on/off control to suit the actual daily drive distance of users.