Air Spring Research Articles

웨이퍼 본딩 장비용 Uniform Press 개발

스마트폰을 비롯한 고성능 모바일 전자기기의 발전에 따라서 경박단소한 전자부품의 요구가 커지고 있으며 이를 위해서 새로운 패키징 방법이 탄생하고 있다. 이러한 새로운 패키징 공정에서 웨이퍼 본딩 공정이 많이 요구되고 있다. 웨이퍼 본딩에서 많이 활용되는 방법이 열 압착 방법으로 가열된 헤드로 웨이퍼에 압력을 가하여 본딩하는 방법이다. 열 압착 방법에서 요구되는 공정조건은 온도 균일성과 Uniform Press이다. 온도 균일성은 마이크로 히터와 열 해석을 통한 설계로 비교적 쉽게 요구조건을 만족 시킬 수 있지만 Uniform Press를 가공과 조립으로만 요구조건을 만족시키기 위해서는 매우 높은 정밀도가 요구된다. 열 압착 방법은 고온에서 동작되므로 열 변형에 대한 기계적인 오차를 고려하여 설계, 가공, 조립이 진행되어야하므로 많은 어려움이 따른다. 본 연구에서는 Air 스프링과 Metal Form의 자가 보정장치를 이용하여 가공, 조립, 열 변형으로 발생하는 기계적 오차를 보상하여 성능과 신뢰성을 향상시켰다.

A Study of Pressure-Dependent Squeeze Film Stiffness as a Resonance Modulator Using Static and Dynamic Measurements

We report on the resonant frequency modulation of inertial microelectromechanical systems (MEMS) structures due to squeeze film stiffness over a range of working pressures. Squeeze film effects have been studied extensively, but mostly in the context of damping and $Q$ -factor determination of dynamic MEMS structures, typically suspended over a fixed substrate with a very thin air gap. Here, we show with experimental measurements and analytical calculations how the pressure-dependent air springs (squeeze film stiffness) change the resonant frequency of an inertial MEMS structure by as much as five times. For capturing the isolated effect of the squeeze film stiffness, we first determine the static stiffness of our structure with atomic force microscope probing and then study the effect of the air spring by measuring the dynamic response of the structure, thus finding the resonant frequencies while varying the air pressure from 1 to 905 mbar. We also verify our results by analytical and Finite Element Method calculations. Our findings show that the pressure-dependent squeeze film stiffness can affect a rather huge range of frequency modulation (>400%) and, therefore, can be used as a design parameter for exploiting this effect in MEMS devices.

Analysis of semi-active vehicle suspension system using airspring and MR damper

With the new advancements in vibration control strategies and controllable actuator manufacturing, semi-active actuators and dampers are finding their way as an essential part of vibration isolators, particularly in vehicle suspension systems. This is attributed to the fact that in a semi-active system, the damping coefficients can be adjusted to improve ride comfort and road handling performances. The currently available semi-active damper technology uses MR fluid to control the damping characteristics of the suspension system. In addition to MR dampers, combining air springs in a semi-active suspension system leads to better handling and ride performance in vehicles. Furthermore, the use of air spring in semi-active suspension system helps to ease design of variable spring stiffness. This easy design opportunity leads to independent control of stiffness and ride height of the vehicle. This paper deals with the design and modelling of variable stiffness air spring for semi-active suspension system, modelling of semi-active suspension systems with variable stiffness and MR damper, and study their

Using magnetorheological fluids in an innovative hybrid bicycle damper

Magnetorheological fluids are capable of changing their viscosity quickly. This can provide good controllability and fast dynamic response. A conventional passive suspension system with air spring or hydraulic damper has simple design and financial benefit for bicycles, but its operation is uncontrollable and non-adaptive. This paper presented a semi-active hybrid bicycle suspension system which combines conventional air spring and a new magnetorheological damping brake together to reduce vibration of a bicycle. A multi-layer magnetorheological brake and linkage mechanism are connected to bike fork to form the adaptive damping part of the innovative hybrid suspension system. The simulation results proved that the semi-active suspension system can reduce bike vibration effectively.

OUTLOOK CONSTRUCTION SPRING SUSPENSION VEHICLES

A study of the prospects for the development of construction spring suspension vehicles. It was foundthat high-speed trains, where the requirements for smoothness of motion is significantly higher than inpassenger cars, used a two-stage spring suspension with static deflection of 0.3 to 0.5 m, which is achievedthrough the use of air springs, where an elastic member is compressed air.

Encyclopedia of automotive engineering

Encyclopedia of automotive engineering

Simulation of Electrical Actuator and Air Spring Actuator Controlled Suspension Systems for Automotive Vehicles

This article discusses methods to reduce the acceleration of a vehicle and increase its road holding ability. In the simulation using quarter car model, electric actuator and air spring based actuator are used as the main control elements. A three degrees of freedom system model is used in which the parameters for the tire, vehicle body and seat are considered. The required actuator force is calculated by a standard fuzzy controller. For analysing the performance of active suspension system, body acceleration and velocity are given as inputs to the controller according to ISO specified standards. Accelerations of the seat and vehicle body are used to judge the performance of the system.

Hydrological resilience of a Canadian Rockies headwaters basin subject to changing climate, extreme weather, and forest management

AbstractMarmot Creek Research Basin in the Canadian Rockies has been the site of intensive streamflow, groundwater, snow accumulation, precipitation, and air temperature observations at multiple elevations. The basin was instrumented in 1962, subjected to forestry experiments in the mid‐1970s, and experienced extreme flooding in 2013. Climate change, forest cover change, and recent extreme weather make the basin an ideal laboratory for studying hydrological resilience. Observations show increases in low elevation air temperature, multiple day and spring precipitation, interannual variability of precipitation, and high elevation groundwater levels. Observations also show decreases in peak seasonal snow accumulation and low elevation groundwater levels. Despite these substantial hydrometeorological and groundwater changes, streamflow volume, timing of peak, and magnitude of the peak are not changing. Streamflow volumes are also insensitive to forest cover changes and teleconnections. The June 2013 flood was unprecedented in the period of record, and the basin significantly moderated the hydrological response to the extreme precipitation; the 2013 storm precipitation depth was 65% greater than the next highest storm total over 51 years; however, the 2013 peak streamflow was only 32% greater than the next highest peak flow recorded. The hydrology of Marmot Creek Research Basin displays remarkable resilience to changing climate, extreme weather, and forest cover change. Copyright © 2015 John Wiley & Sons, Ltd.

Hierarchical control of ride height system for electronically controlled air suspension based on variable structure and fuzzy control theory

The current research of air suspension mainly focuses on the characteristics and design of the air spring. In fact, electronically controlled air suspension (ECAS) has excellent performance in flexible height adjustment during different driving conditions. However, the nonlinearity of the ride height adjusting system and the uneven distribution of payload affect the control accuracy of ride height and the body attitude. Firstly, the three-point measurement system of three height sensors is used to establish the mathematical model of the ride height adjusting system. The decentralized control of ride height and the centralized control of body attitude are presented to design the ride height control system for ECAS. The exact feedback linearization method is adopted for the nonlinear mathematical model of the ride height system. Secondly, according to the hierarchical control theory, the variable structure control (VSC) technique is used to design a controller that is able to adjust the ride height for the quarter-vehicle anywhere, and each quarter-vehicle height control system is independent. Meanwhile, the three-point height signals obtained by three height sensors are tracked to calculate the body pitch and roll attitude over time, and then by calculating the deviation of pitch and roll and its rates, the height control correction is reassigned based on the fuzzy algorithm. Finally, to verify the effectiveness and performance of the proposed combined control strategy, a validating test of ride height control system with and without road disturbance is carried out. Testing results show that the height adjusting time of both lifting and lowering is over 5 s, and the pitch angle and the roll angle of body attitude are less than 0.15°. This research proposes a hierarchical control method that can guarantee the attitude stability, as well as satisfy the ride height tracking system.

Experimental and simulation study on the vibration isolation and torsion elimination performances of interconnected air suspensions

This paper extends recent research on the dynamic performance of an interconnected air suspension. Although some aspects of the dynamic performance of such suspension systems have been studied, little attention has yet been paid to the torsion elimination performance or to the way in which the form of interconnection influences the interconnecting effectiveness. A model car test bench equipped with interconnected air spring suspensions is constructed and the vibration isolation performances of different interconnections are compared. The test results show that the r.m.s. acceleration value of the vehicle body is reduced by 1.2–6.1% using a lateral interconnection, while it is reduced by 0.1–3.3% using a longitudinal interconnection, because of the longer interconnecting pipes. Further research proves that laterally interconnected air suspensions can gain interconnecting effectiveness by using shorter and thinner interconnecting pipes, and this means that they are more suitable for small- and medium-sized vehicles. When the deformation of the vehicle body is considered, a new eight-degree-of-freedom mathematical model is designed and verified by test examination. This model is used to study the torsion elimination performance, the roll performance and the pitch performance of a laterally interconnected air suspension. It shows that the peak torsional load of the vehicle body under step examination is reduced by 6.68–17.65% on interconnection and, after entering the steady state, the torsional load is almost eliminated. The body roll angle which is caused by the road roughness is reduced by around 6%, while the pitch angle shows little change.

Stress Analysis of Aluminium Reinforced Air Springs

There has been a recent increase in emphasis on comfort in most vehicular transports these days. Air springs were used and then removed from commercial usage. This paper conducts an analysis to showcase the improvement it terms of material application by using rubber which is reinforced with aluminium to increase its performance and strength. FEA is carried out to simulate various load conditions with respect to both rubber and rubber reinforced with aluminium. The structural changes are noted and described.

Equivalent Air Spring Suspension Model for Quarter-Passive Model of Passenger Vehicles.

This paper investigates the GENSIS air spring suspension system equivalence to a passive suspension system. The SIMULINK simulation together with the OptiY optimization is used to obtain the air spring suspension model equivalent to passive suspension system, where the car body response difference from both systems with the same road profile inputs is used as the objective function for optimization (OptiY program). The parameters of air spring system such as initial pressure, volume of bag, length of surge pipe, diameter of surge pipe, and volume of reservoir are obtained from optimization. The simulation results show that the air spring suspension equivalent system can produce responses very close to the passive suspension system.

Research on the vertical stiffness of a rolling lobe air spring

A new analytical formula to describe the vertical stiffness of a rolling lobe spring has been established; the equation incorporates the rate of change of the effective area of the spring. Two rolling lobe air springs were studied by performing analytical calculations, and the results were verified by comparisons to finite element simulations and experimental data. The analytical formula can be used to qualitatively predict the vertical stiffness of a rolling lobe air spring. Precise prediction of the value of the vertical stiffness can be obtained using the formula in cases where the reservoir volume is not very large. The influence of geometric parameters on the vertical stiffness of a rolling lobe air spring has been studied using the proposed formula and a guideline for its design has been obtained by plotting a cause–effect chart.

Comparison of Air Spring Actuator and Electro-Hydraulic Actuator in Automotive Suspension System

The present article introduces an approach that combines modelling and simulation of air spring actuator and electro-hydraulic actuator for comparison in automotive suspension system. Both hydraulic and air spring actuators are controlling the vehicle body by developing a desired force between sprung mass and unsprung mass using fuzzy logic controller. The vehicle body along with the wheel system is modelled as a two degree of freedom quarter car model. The actuator performance is investigated using the quarter car suspension model under single road bump with severe peak amplitude excitations and random road input. From the results of simulation, it can be concluded that air spring actuator gave better performance than electro-hydraulic actuator in all conditions under vertical body deflection.

The Dynamic Characteristic and Hysteresis Effect of an Air Spring

In many applications of vibration technology, especially in chassis, air springs present a common alternative to steel spring concepts. A design-independent and therefore universal approach is presented to describe the dynamic characteristic of such springs. Differential and constitutive equations based on energy balances of the enclosed volume and the mountings are given to describe the nonlinear and dynamic characteristics. Therefore all parameters can be estimated directly from physical and geometrical properties, without parameter fitting. The numerically solved equations fit very well to measurements of a passenger car air spring. In a second step a simplification of this model leads to a pure mechanical equation. While in principle the same parameters are used, just an empirical correction of the effective heat transfer coefficient is needed to handle some simplification on this topic. Finally, a linearization of this equation leads to an analogous mechanical model that can be assembled from two common spring- and one dashpot elements in a specific arrangement. This transfer into ”mechanical language” enables a system description with a simple force-displacement law and a consideration of the nonobvious hysteresis and stiffness increase of an air spring from a mechanical point of view.

Influence of the Shock Absorbers Type Change at Stress of the Trolleybus Chassis

ŠKODA VÝZKUM cooperated on the development of the NEOPLAN DMA low-floor articulated trolleybus intended for the Boston city (the United States). Multibody models and finite element models of the trolleybus were utilized in the stage of the vehicle design. The multibody models of the trolleybus were created in the alaska simulation tool and the simulations were especially aimed at determining forces acting in the trolleybus suspension elements and radius rods. At the end of the stage of computer modelling and testing the trolleybus prototype a decision to change the type of shock absorbers used in the axles' suspension was made. The impact of this change on forces acting in the trolleybus suspension elements (i.e. in air springs and shock absorbers) and radius rods on the trolleybus chassis when running on an uneven test track was investigated using multibody simulations. Time histories of the forces calculated utilising multibody models were used as input data of the trolleybus finite element models. Stress in the critical places of the trolleybus body structure was determined utilizing the finite element models.

Analysis of Energy Efficiency of a Test Rig for Air Springs

During dynamic testing of vehicle air springs, work is required for loading the springs. This work is partially returned by the spring to the driving system during the release phase. Testing is energy-efficient when at least a portion of the returned work can be utilised. This was taken into account in the design of the new inovative test rig for the simultaneous testing of four air springs. There is a phase shift between the phases of loading individual air springs; thus, the work returned to the drive system by a spring during its release is also used for loading another spring. The test rig was constructed and operates in the laboratory of an air spring manufacturer. We developed a computer program to analyse the energy situation in the test rig. The program calculates the work required for loading the springs, power and friction for different sizes of springs and test conditions. In this paper, computational algorithms are deduced and the results of the calculation for the treated spring are presented. The energy situation in the test rig during start-up and operation is discussed, taking into account the energy loss due to the hysteresis of springs and friction losses. The friction losses are evaluated for different implementations of critical elements. The influence of a flywheel on conditions during the start-up and operation of the test rig is analysed.

Study on Air Spring Model

A new non-linear dynamic model of the air spring system(TPL-ASN model) includes the sub-models of the orifices, the connecting pipes and all the chambers is established based on the theories of aerodynamics, fluid mechanics and engineering thermodynamics, etc. Three quarter-car dynamics simulation models respectively include the equivalent model, the linear model and the TPL-ASN model are set up using the dynamics simulation software SIMPACK and the self-designed air spring dynamic characteristics simulation software ASDS. The dynamic characteristics of a high-speed electric multiple unit(EMU) air spring are calculated under different excitation amplitudes and frequencies, and take the simulation results of the dynamic stiffness, the damping ratio and the transmission ratio compare with the experimental results. Results show that, the simulation results of the equivalent model and the linear model have great difference with the experimental results, the two models can not accurately reflect the amplitude characteristics and the frequency characteristics of the dynamic stiffness, the damping ratio and the transmission ratio, but the simulation results of the TPL-ASN model are in good agreement with the experimental results. All the results show that the TPL-ASN model can accurately simulate the air spring non-linear dynamic characteristics.

Contribution to the modeling of a pneumatic semi-active control of vehicle suspension

This paper contributes to the modeling of a semi-active control of a quarter vehicle model using air springs. A conventional mass-spring-damper model has been used along with an air spring. Based on the theory of thermodynamics, the dynamic equation of the air spring model was established. The simulation model was implemented using MATLAB and the transfer functions with varying parameters were calculated. The simulation results show that air spring pressure, the valve diameter, the dumping coefficient and the mechanical stiffness affect the dynamic response of the system. A semi-active control methodology was then established by controlling the valve diameter using two declinations of an on-off logic switch based on the velocity of the suspended mass and the relative velocity at both ends of the air spring. The obtained results show reduced oscillation amplitudes around the natural frequency of the system.

Analysis Of Mechanical Loading of the Hinges and Supports of the Mold Vibration Mechanism on a Continuous Caster

The mechanical loading of a hinge-lever mold-vibration mechanism on a continuous caster is modeled to examine how the use of air springs that perform a balancing function affect the dynamic component of the reaction forces in the mechanism’s hinges and supports. The values of pressure in the air springs that are optimum from the standpoint of minimizing the range of variation of the reaction forces are determined.