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To provide initial design values of seat cushion and chassis suspension damping for wheel-drive electric vehicles (WDEVs), this paper presents an analytical estimation method and a practical damping parameters design method. Firstly, two formulae of the human body vertical acceleration in terms of the power spectrum density (PSD) and the root mean square (RMS) are deduced for WDEVs. Then, the coupling effects of the key vehicle parameters on ride comfort are revealed. Finally, with a practical example, the damping parameters of the cushion and the suspension are initially designed and analyzed. The results show that when every 10.0 kg increases for motor mass, the optimal damping values of the cushion and the suspension should be reduced by about 15.0 Ns/m and 50.0 Ns/m, respectively. However, the RMS acceleration increases 0.017 m/s2 with a decrease of 2.5 % for ride comfort.

To meet the requirements of throttle slice stress intensity and damping characteristics for special vehicle, the shock absorber needs to adopt variable-thickness throttle slice, but there is no accurate stress analytic computation formula for it, thus, the fracture failure of the valve often occurrs. Based on the mechanics model of variable-thickness throttle slice, the general solutions of the differential equation of throttle slice on uniform pressure was given, and the deformation analytic formula was established. With the relations of the deformation, the inner force, and the stress of the throttle slice, the analytic formulae of radial, circumferential and compound stress at any radius were given, and the slice stress coefficients were built. The stress of variable-thickness throttle slice on uniform pressure at any radius was computed, and was testified by ANSYS, the value computed was close to that simulated, and the maximum of the relative deviation was less than 0.8%. With a practical example, by test, the stress analytic computation formula was validated. The test results showed the valve designed met the requirements of stress intensity and stiffness and the stress computation method was reliable, which has important reference value for variable-thickness throttle slice design and intensity analysis.

In this paper, a 3-DOF (degree-of-freedom) model of quarter-car coupled with driver and cushion is used to derive an analytical formula, which can describe the driver RMS (root-mean-square) acceleration response with cars under random excitation generated by road irregularities. The study starts with the 3-DOF model. Based on the vehicle random vibration theory, using the residue theorem, the analytical formula of driver RMS acceleration considering cushion effects is obtained. Then, the driver RMS acceleration values calculated from the measured data and from the analytical formulae of the 3-DOF and the classical 2-DOF model are compared. The results show the analytical formula for the 3-DOF model provides a more reasonable approximation of the real response of the test car. Having obtained the analytical formula, the effects of vehicle parameters on driver RMS acceleration are studied. Finally, to provide critical foundations for the selection of the cushion damping, the optimal damping ratio of...

This paper describes improved ride comfort of a novel nonlinear suspension for seat system based on field measurements. For the novel nonlinear suspension proposed, a rubber spring is used as its elastic element which has highly nonlinear characteristics to adapt various working conditions, and an asymmetrical damper is designed to yield asymmetric damping characteristics. Previous seat models were not very suitable for the system; thus, a nonlinear mathematical model was built to describe it better. Then, based on field measurements, the model parameters were identified, and the suspension damping coefficients were tuned under the practical constraints, to achieve satisfactory ride comfort to the greatest extent possible. Finally, the bench test was carried out, and the results show that, after the coefficients tuning, the seat vertical frequency-weighted root mean square (RMS) acceleration values are decreased by about 10 % and 8 % under the driving conditions on the highway and the gravel road, respectively, which proves the damping coefficients tuned are workable. The novel nonlinear suspension and the method of the damping coefficients tuning provide a valuable reference for further improving ride comfort to better protect the driver's health. Cilj predstavljene študije je izboljšanje udobja pri vožnji z novim sistemom nelinearnega vzmetenja sedežev na podlagi terenskih meritev. Analiziran je bil nov voznikov sedež, razvit za uporabo v težkih tovornjakih. Vzmetenje je zasnovano kot običajen škarjasti sistem, vanj pa sta vgrajena votla gumijasta vzmet in hidravlični blažilnik. Elementa sta pritrjena na školjko in na ogrodje sedeža med škarjasto konstrukcijo. Gumijasta vzmet deluje kot elastičen element z visokonelinearno karakteristiko, ki omogoča prilagajanje različnim delovnim pogojem, asimetričen blažilnik pa zagotavlja asimetrično karakteristiko dušenja. Obstoječi modeli sedežev niso bili primerni za ta sistem, zato je bil za boljši opis razvit nov nelinearen matematični model.

To facilitate the initial design and stiffness matching of rubber bushing, according to the elastic mechanics theory, based on the analysis of the measured curve of radial deformation, by imposing virtual constraint stress on both ends of the bushing, the deformation analytic formula of rubber bushing on a radial concentrated force was established. With a practical example, the radial static deformation formula was computed and verified by simulation using ANSYS and test, and the analytical value is close to the simulated and the tested. The results show that the method of radial deformation analytic computation of rubber bushing under small deformation assumption is reliable and this method has important reference value for suspension design of vehicles.

The stiffness parameters of cabin suspension have an important effect on the comfort of fork lift trucks. Analysis of the cabin system of fork lift trucks often requires the retrieval of the stiffness parameters of cabin suspension systems. Convenient methods of retrieving stiffness parameters without dismantling the cabin suspension system cannot be obtained unless a special bench test is conducted. This process is inconvenient for researchers and technicians. A cabin model with three degrees of freedom was constructed, including a simulation model, to provide a convenient method for retrieving stiffness parameters. A model for the identification of stiffness parameters was established on the basis of the test data and the simulation model. The stiffness parameters were identified through a case study and the values retrieved coincide with the test results. The results show that the method built is reliable and provides an effective way of retrieving the stiffness parameters of cabin suspension for fork lift trucks.

The main aim of this work was to provide a convenient method to gain the dynamic parameters of a type of cabin system with an acceptable accuracy quickly and efficiently. To start this research, the vibration equations of a 3-DOF cabin model for a heavy truck were built. To retrieve the values of the dynamic parameters, a quadratic error vector function was presented, and the multi-island genetic algorithm was adopted to solve this problem. With a practical example, based on the collected signals, the dynamic parameter-integrated identification was carried out, and the results show that the stability of the solving algorithm for the integrated identification is very well, and the identified values of the model parameters are reliable. In the end, the experimental research was conducted, and the identified values were compared with the tested and those obtained by other methods. The results further prove that the integrated identification method of the dynamic parameters is feasible. This method is particularly suitable for the condition that the dynamic parameters are all unknown.

For the complex structure and vibration characteristics of the seat and cab system of truck, there is no reliable theoretical model for the suspensions design at present, which seriously restricts the improvement of ride comfort. In this paper, a 4 degree-of-freedom seat-cab coupled system model was presented; using the mechanism modeling method, its vibration equations were built; then, by the tested cab suspensions excitations and seat acceleration response, its parameters identification mathematical model was established. Combining the tested signals and a simulation model with the parameters identification mathematical model, a new method of hybrid modeling of seat-cab coupled system was presented. With a practical example of seat and cab system, the parameters values were identified and validated by simulation and test. The results show that the model and method proposed are correct and reliable, and lay a good foundation for the optimal design of seat suspension and cab suspensions to improve ride comfort.

Both the seat and cab system of truck play a vital role in ride comfort. The damping matching methods of the two systems are studied separately at present. However, the driver, seat, and cab system are one inseparable whole. In order to further improve ride comfort, the seat suspension is regarded as the fifth suspension of the cab, a new idea of “Five-suspensions” is proposed. Based on this idea, a 4 degree-of-freedom driver-seat-cab coupled system model is presented. Using the tested cab suspensions excitations as inputs and seat acceleration response as compared output, the simulation model is built. Taking optimal ride comfort as target, a new method of damping collaborative optimization for Five-suspensions is proposed. With a practical example of seat and cab system, the damping parameters are optimized and validated by simulation and bench test. The results show the seat vertical frequency-weighted RMS acceleration values tested for the un-optimized and optimized Five-suspensions are 0.50 m/s2 and 0.39 m/s2, respectively, with a decrease by 22.0%, which proves the model and method proposed are correct and reliable. The idea of “Five-suspensions” and the method proposed provide a reference for achieving global optimal damping matching of seat suspension and cab suspensions.

For the complex structure and vibration characteristics of coupling driver-seat-cab system of trucks, there is no damping optimisation theory for its suspensions at present, which seriously restricts the improvement of vehicle ride comfort. Thus, in this paper, the seat suspension was regarded as ‘the fifth suspension’ of cab, the ‘Five-suspensions’ for this system was proposed. Based on this, using the mechanism modelling method, a 4 degree-of-freedom coupling driver-seat-cab system model was presented; then, by the tested cab suspensions excitation and seat acceleration response, its parameters identification mathematical model was established. Based on this, taking optimal ride comfort as target, its damping collaborative optimisation mathematical model was built. Combining the tested signals and a simulation model with the mathematical models of parameters identification and damping collaborative optimisation, a complete flow of hybrid modelling and damping collaborative optimisation of Five-s...

Both stiffness and damping parameters of cabin suspension have important influences on the dynamic performance of cabin system for heavy truck. To theoretically study ride comfort of cabin system, the stiffness and damping parameter values of cabin suspension are often required. At present, there is no convenient method unless by bench test to accurately obtain all the stiffness and damping parameters; however, the cost of bench test is relatively high and inconvenient. In this article, according to the real cabin system of a heavy truck, a 3 degree-of-freedom cabin system linear model was presented and its vibration equations were built. By the tested cabin suspension excitations and seat acceleration response, based on curve fitting method, a stiffness and damping parameter identification mathematical model was established. With a practical example of cabin system, the stiffness and damping parameters were identified and validated by bench test. The results show that the built model and the proposed method are workable and lay a good foundation for the theoretical analysis and/or optimal design of cabin suspension to improve ride comfort.

During the dynamic simulation of cabin system, the damping parameters values of cabin suspension are the key factors. In previous work, for obtaining all the parameters of the cabin system of trucks for long distance transport, a parameters identification model was built by minimizing the error of the root-mean-square acceleration between the tested and the measured. However, the identification precision is not high. In this paper, according to the real cabin system of a heavy duty truck for short distance transport, a 3-DOF model of cabin system was built. Based on curve fitting method, a new identification model for damping parameters was established. At last, the bench test was done and the comparisons were conducted among the tested values, the values identified by the method built in this work, and those obtained by the method built in previous work. The results show that the model built and the method proposed are feasible, and the identification precision is higher than the previous work.

The seat-cabin system of fork lift trucks has a great influence on ride comfort. On the basis of the structure and characteristics of the seat-cabin system for a high-grade fork lift truck, a seat-cabin system vertical dynamic model was created. The vertical dynamic responses of the model under the random irregularities excitation were calculated. The calculated responses including the seat dynamic response and the cabin dynamic responses at the four corners are very close to the field measurement data and the relative deviations of the (root mean square) RMS acceleration responses are all less than 6.0%. The results show that the vertical dynamic model is acceptable and can truly describe the basic mechanical behavior of the seat-cabin system. The model provides a good basis for investigating the relations between the dynamic parameters and the vibration attenuation characteristics of the seat-cabin system to further improve ride comfort.

For the driver's seat system of buses, its design often needs trial and error, which usually has longer periods, higher cost, and larger waste. In this paper, a three degrees-of-freedom driver's seat system model was built. Based on the tested seat suspension excitation and cushion acceleration response, its parameters identification model and damping identification model were established, respectively. Combining the mechanism modelling with the parameters identification model and damping identification model, an integrated and convenient method of modelling, damping optimisation, and accompanying verifications for the driver's seat system was presented. With a practical example, the method and the dynamic model were validated by simulation and test. The measured cushion vertical frequency-weighed RMS acceleration values of the driver's seat system for the un-optimised and the optimised are 0.588 m/s2 and 0.533 m/s2, respectively, with a decrease of 9.35%. The results show that the method and the dynamic model presented are correct and workable.

High-power synchronous motor is difficult to start and unable to start and stop freely, so it must be long-running. This will cause a lot of energy waste. In order to solve the problem, devices of self-controlled soft start with variable frequency for high-power synchronous motor are researched and developed. The TMS320F2812 DSP is used as main control chip to do all the control strategies in this soft-start platform. This paper also gives a detailed method to do with the error signal of misleading zero-crossing points of back-EMF caused by inverter commutation, and describes the problem at the switch point from self impulse to back-EMF zero-crossing detection. It can get the rotor position without position sensor by accurate detection of motor back-EMF zero-crossing at medium and high speed. In the prototype platform, the motor can be soft started from standstill to rated speed stably and reliably.

Selective catalytic reduction (SCR) de-NOx reaction in flue gas is the main de-NOx technology used in power plants. In this technology, de-NOx catalyst is the key content of SCR technology. And the industrial experiment is the necessary link of de-NOx catalyst research process. In this paper, according to the power plant conditions, the industrial test platform was designed and carried out. The catalyst was analyzed and appraised. And the function curves of catalyst were acquired. It was useful for establishing industrial evaluation standard of the de-NOx catalyst in producing period.

The mechanics model of flexible ring throttle-slice and the differential equation of its deformation are established based on elastic mechanical principals. Utilizing the boundary condition, the general solution of elastic ring throttle-slice's deformation curved surface is obtained, and a deformation co-efficient of elastic throttle-slice is formed by identical transfor-mation of the general solution of elastic throttle-slice. Then a precise method for calculating ring throttle-slice deformation is put forward. The bending deformation of throttle-slice is ana-lyzed based on the deformation coefficient, and comparison with two common-used approaches is also performed about influence of calculation deviation on design and performance of damper. The effect of the equivalent thickness of superposition throttle-slices on throttle opening size is studied. Experimental results on telescope-damper performance at different superposi-tion throttle-slices show that the research can play an important role at damper valves design.