Design Optimization of an Integrated E-Type Multilink Suspension Wheel-Side Drive System and Improvement of Vehicle Ride Comfort

Distributed-drive electric vehicles constitute an important research direction for the future development of electric vehicles. In this regard, the integrated suspension wheel-side drive system has considerable development potential because it can address the lack of driving smoothness and the grounding deterioration caused by the excessive unsprung mass of the distributed-drive system. However, a complete and systematic description of the design of such a system is not available in the literature. Therefore, this paper proposes a design process for an integrated E-type multilink suspension wheel-side drive system and a method to improve the vehicle ride comfort. Based on a configuration analysis of the E-type multilink suspension using the orientation feature set method, the ADAMS platform was used to optimize the hard point coordinates of the suspension with the integrated E-type multilink suspension wheel-side drive system as the object, and the spring stiffness and damper were designed considering the driving smoothness and the grounding of the vehicle. The bushing stiffnesses were determined through tests, and the feasibility of each bushing installation was determined via elastic kinematic simulation of the integrated E-type multilink wheel-side drive system; then, optimization design of bushing stiffness was carried out for ride smoothness. Then, a lightweight design of the gears’ reducer was performed. Finally, the specific structural design and strength verification of the key components of the designed system were conducted. The results indicated that the strength of each component of the wheel-side drive system met the requirements. Thus, the overall design process of the integrated suspension wheel-side drive system was improved. This study can therefore serve as a reference for the integrated design and vehicle ride comfort improvement of wheel-side drive systems and suspensions.

The Texture and Structure of the Melt-Spun Co2MnAl-Type Heusler Alloy

The structure of the Co2MnAl-type Heusler alloy in the form of a melt-spun ribbon was studied by electron microscopy, electron back-scattered diffraction (EBSD), and X-ray diffraction. The melt-spun ribbon consists of a homogeneous single-phase disordered Heusler alloy at the wheel side of the ribbon and an inhomogeneous single-phase alloy, formed by cellular or dendritic growth, at the free surface of the ribbon. Cellular growth causes the formation of an inhomogeneous distribution of the elemental constituents, with a higher Co and Al concentration in the centre of the cells or dendritic arms and a higher concentration of Mn at the cell boundaries. The EBSD analysis shows that the columnar crystals grow in the <111> crystal direction and are declined by about 10° against the direction of the spinning.

Research on bifurcation and control of electromechanical coupling torsional vibration for wheel-side direct-driven transmission system

Aiming to the torsional vibration destabilization phenomenon of the wheel-side transmission system direct-driven by the high-power motor, the system torsional vibration bifurcation characteristics and control strategy are analyzed. Through defining the system electromechanical coupling relationship between the electrical link and the mechanical link, the dynamic model of the wheel-side direct-driven transmission system is constructed. Then, based on the Routh–Hurwitz stability criterion, the system Hopf bifurcation characteristics caused by the change of the wheel-ground friction during driving are revealed. Furthermore, with the nonlinear feedback controller and the Washout filter combined, the system torsional vibration stabilization controller is constructed by introducing the system torsional vibration signals into the motor control voltage. The results show that the linear part of the torsional vibration stabilization controller can effectively change the system stability region, as well as the cubic nonlinear part of the torsional vibration stabilization controller can control the stability of the system bifurcation points and suppress the limit cycle amplitude. The research results can provide theoretical basis and technical support for the performance improvement and integrated application of the wheel-side direct-driven transmission system in the electric bus.

Numerical and Experimental Investigation of the Sealing Effect of a Specific Labyrinth Seal Structure

A numerical simulation and experimental study were performed to investigate the sealing effect of the labyrinth seal used in a wheel-side reducer. A three-dimensional computational fluid dynamics model was established based on the labyrinth structure. The effects of the temperature and viscosity of lubricant, rotor speed, pressure ratio, clearance, and cavity size of the sealing structure on the sealing were analyzed, and the leakage amount under the corresponding values of different factors was also analyzed. The results indicated that increase in the lubricating oil temperature, viscosity, pressure ratio, and seal clearance lead to decrease in the sealing effect and increases in the leakage. And the effect of rotational speed on the seal is low. To verify numerical simulation, the results of numerical analysis, a test bench was set up to simulate the work of the reducer, and the sealing effect of the sealing structure was examined. The simulation result was compared with the actual results. Both the numerical simulation and experiment indicate that the labyrinth seal achieves the desired sealing effect.

Influence of Preparation Technology on Microstructural and Magnetic Properties of Fe2MnSi and Fe2MnAl Heusler Alloys

Microstructural and magnetic properties of the X2YZ, namely Fe2MnSi and Fe2MnAl, Heusler alloys have been studied from the viewpoint of technology for their production and for the Z element effect. First, arc melting was applied to produce button-type ingots from which samples in a form of 500 µm thick discs were cut. Second, planar flow casting technology yielded samples in a ribbon-form 2 mm wide and 20 μm thick. The checked area chemical compositions were in agreement with the nominal ones. Nevertheless, the darker square objects and smaller bright objects observed at the wheel side of the Fe2MnSi ribbon sample yielded higher Mn content at the expense of Fe. The X-ray diffraction patterns of all samples have indicated L21 structure with lattice parameters, 0.567 (1) nm for Fe2MnSi and 0.584 (1) nm for Fe2MnAl, being within an experimental error independent of production technology. On the other hand, the technology has markedly influenced the microstructure clearly pointing to the larger size of grains and grain boundaries in the disc samples. From the magnetic viewpoint, both alloys are paramagnetic at room temperature without visible influence of their production. On the contrary, the low-temperature behavior of the microscopic hyperfine parameters and the macroscopic magnetic parameters exhibits differences affected by both chemical composition and microstructure.

Lightweight design of gears in the wheel-side reducer based on Shanghai road driving cycle

The development of wheel-side reducer with proper durability is important for electric vehicles equipped with a wheel-side reducer system. Based on the Shanghai road driving cycle, a novel conversion method is proposed from vehicle speed to load, which provides a theoretical foundation for lightweight design and a durability analysis of the key components of the wheel-side reducer system. With the gears of the wheel-side reducer as an example, an electric drive system durability test specification is also developed on the basis of the Miner linear cumulative damage theory considering the material strengthening under low-amplitude loads. The durability test shows that the second round of the prototype design no longer has an infinite life compared with the first round of the prototype design. The method based on active load spectrum is more effective than the traditional design method.

Robust H∞ control design of an electromagnetic actuated active suspension considering the structure non-linearity

Electromagnetic actuated active suspension (EAAS) benefits energy harvesting while providing active control. However, the inertia of the actuator introduces an equivalent mass coupled with the sprung and unsprung mass. In addition, the specific structure of the suspension features structure non-linearity, which results in the perturbation of the equivalent mass of the actuator, the variation of the transmission ratio of the actuator output torque to the actuator force at the wheel side and an extra force to be compensated with. A dynamic model of active control considering the equivalent mass and the structure non-linearity is proposed. Based on a gearbox type EAAS, respective non-linearity is studied. For multi-objective optimization, a robust controller is designed with proper weighting functions. A virtual prototype of the EAAS is built and simulated with a bump/pothole and random excitation road profiles. Results show that neglecting the structure non-linearity effects influences the accuracy of active control. The investigation of this paper provides a fundamental methodology for the control design of actual applications of EAASs.