Suspension Shock Absorber Research Articles

Research on Inertial Force Attenuation Structure and Semi-Active Control of Regenerative Suspension

To improve the energy recovery ability of the energy-regenerative suspension, a transmission is generally used to increase the motor speed, but this results in a significant increase in the equivalent inertial mass of the suspension. The research on energy-regenerative suspension has been ongoing for more than 20 years, but there have been few product applications, mainly due to the failure to solve the problem of the deterioration of suspension performance caused by equivalent inertial mass. This paper proposes a new suspension configuration with the suspension shock absorber connected to a high-frequency vibration reduction structure and establishes a vibration transmission model. Through frequency domain analysis, it has been conclusively proven that the new-configuration can significantly reduce both the sprung mass acceleration and relative dynamic load of the energy regenerative suspension. On the basis of frequency domain analysis, a scheme based on PWM control of the dissipation resistance value of the energy regenerative suspension is proposed, and through bench comparison experiments, it has been verified that the new-configuration suspension can eliminate the oscillation of the damping force curve of the shock absorber and significantly improve the suspension performance. Further experiments show that using the skyhook semi-active control algorithm the new-configuration suspension can further reduce the sprung mass acceleration and relative dynamic load.

INFLUENCE OF SHOCK ABSORBER PROPERTIES ON TIRE LATERAL FORCE

The article examines how the damping properties of the suspension system of a vehicle affect the process of forming a lateral reaction in the contact patch of a tire and the supporting surface. A mathematical model of a car quarter, a tire stretched string model, and a road surface microprofile generator were used in the study. The dependences of normal and lateral reactions along the distance traveled for three classes of roads were obtained with a change in the parameter characterizing the damping properties of the vehicle suspension. Mathematical statistics methods were used to analyze the dependences. It was found that the average value of the normal load changes little with a decrease in the damping properties of the suspension, while the standard deviation increases. The average value of the lateral force is reduced by 22%, with the standard deviation increasing by 1.6 times. The use of the Kolmogorov-Smirnov criterion for the analysis of implementations of lateral forces makes it possible to determine the permissible range of nominal values of the parameters of the technical condition of vehicle suspension shock absorbers.
 Purpose. Obtaining and analyzing patterns that describe the change in the lateral reaction of a car tire when it moves under the action of a lateral force and suspension vibrations, as well as when changing the damping properties of a shock absorber.
 Methodology. In the article were used the methods of mathematical modeling and also statistical methods of the analysis.
 Results. Dependences have been obtained that characterize the influence of the damping properties of the suspension on the magnitude of the lateral reaction when the wheel moves along a road with bumps and under the action of a lateral force.
 Practical implications. It is expedient to apply the received results by the organizations and institutions involved in the development of methods and means of diagnosing vehicles.

EXPERIMENTAL STUDY OF THE PERFORMANCE CHARACTERISTICS OF SHOCK ABSORBERS

The article discusses the methodology for determining the performance characteristics of Toyota Prius 20 shock absorbers. The study was conducted using a stand for the diagnosis of shock absorbers developed by the Department of Road Transport of INRTU (Irkutsk National Research Technical University). Tests were carried out for five front suspension shock absorbers, one – a new serviceable shock absorber, the rest – shock absorbers that were previously in operation. The experimental dependences of the change in the resistance force of the shock absorber on the speed of movement of its rod are analyzed. The level of operational characteristics of the shock absorber under study was determined by comparing the obtained parameters with the parameters of the new shock absorber.
 The results of experimental studies are presented in the form of operational characteristics of tested shock absorbers and indicators that determine the level of operational characteristics of shock absorbers. The developed methods and the equipment implementing them make it possible to determine the functional dependencies and the level of performance of shock absorbers that were in the operating conditions of the vehicle.

Improving the comfort of truck drivers by using controlled cab suspension shock absorbers

The research addresses the issue of creating a methodology for selecting the damping control law in nonlinear suspension systems and determining the characteristics of controlled shock absorbers in the cab suspensions. The study object is the shock-absorbing support device of the truck cab suspension system. By mathematical modeling of the car dynamics, it is proved the effectiveness of the cab suspension system with controlled shock absorbers and its operability according to the criterion of the possibility of implementing a controlled shock support device in the form of a technical device. Keywords controlled shock absorbers, cab suspension, smoothness running, driver comfort, shock support device

Fuzzy PID control method for damping of electronically controlled air suspension shock absorbers for vehicles

A damping fuzzy proportional-integral-derivative (PID) control method for electronically controlled air suspension shock absorbers was proposed to reduce the RMS values of the body vibration acceleration and improve vehicle ride comfort. Depending on the operating mode of the electronically controlled air suspension shock absorber, a mechanical model of the air suspension shock absorber was established. A fuzzy PID control technology for damping control of the shock absorber is designed by combining a PID control algorithm with the fuzzy control concept. The adaptive expansion factor of the cybernetics domain for the fuzzy PID controller is calculated by considering nonlinear characteristics and time delay to improve the controller’s adaptability. Then, the control parameters are adjusted based on the control deviation and deviation rate parameters. The nonlinear detection platform produced by an enterprise is selected to build an experimental environment for analysis. Simulation results reveal that when the vehicle speed is 30 km h−1, the RMS values of the body vibration acceleration upon applying the proposed method is approximately 0.02 and 0.05 km h−2, respectively, on Class B and C road surfaces. Furthermore, the RMS values of the body vibration acceleration using the proposed method has little fluctuation; when the vehicle speed is 60 km h−1, the RMS values of the body vibration acceleration is 0.022 and 0.028 km h−2, respectively, on Class B and C road surfaces, indicating that the proposed method can effectively reduce the RMS values of the body vibration acceleration and improve rider comfort.

Research on the Stability of Vehicle Active Shock Absorber Based on Intelligent Control System

The traditional vehicle suspension vibration reduction design method uses a fixed damping coefficient to reduce the vibration of the elastic element, and does not consider the different vibration intensity caused by different road conditions and vehicle speeds, and the vibration reduction effect is poor. A finite element design method for vehicle suspension shock absorption optimization is proposed to analyse the function and structure of vehicle suspension shock absorbers. We use the first-order optimization method in the ANSYS finite element software to carry out the optimal design of vehicle suspension damping, and take the damping force of the suspension shock absorber as the optimization objective to carry out the finite element optimization design of the vehicle suspension damping. This ensures that the vibration of the vehicle body is rapidly attenuated, so that the body can quickly reach a stable state. The results show that the fuzzy control strategy can greatly suppress the acceleration of the vehicle body and the dynamic load of the tire, reduce the dynamic travel of the suspension, and the ride comfort, driving safety and operation stability of the vehicle have been significantly improved, and the system suspension has a good comprehensive performance.

Regenerative shock absorber using cylindrical cam and slot motion conversion

Abstract The increasing demand for fossil fuels has led to an increase in their prices; therefore, the regenerative shock absorber (RSA) devices were designed in conjunction with the suspension system industry, in order to reduce the vibration produced whilst driving, which has become a major concern in automobile production. With regards to vehicle development, compared with the current technology, the subject matter of this paper has the following advantages: The current design relates to the RSAs for vehicles, which has an energy recovery function, a simple and new design, a longer life span, a low cost, and are lightweight. A 45° inclined long slot steering mechanism is used in this design to collect the vibration energy generated while driving the vehicle, improving the energy use rate and saving the amount of fuel that is consumed. The reciprocating linear motion in driving the vehicle is converted into a rotational movement. Peak efficiency of 50% and the average efficiency of 45% are demonstrated in the MATLAB system. It converts mechanical energy into electrical energy and restores energy vibration using a suspension shock absorber while driving, which improves energy use and provides greater comfort for passengers while the vehicle is in motion.

Assessment of Production Process Capability in the Serial Production of Components for the Automotive Industry

Abstract The article deals with the assessment of production process capability in the serial production of plastic components. The plastic component was used for analysis. Component is used in the automotive industry in car suspension shock absorbers. Assessing the capability of the product’s manufacturing process is very important. The aim of the present paper is to measure the dimensional characteristics of a thermoplastic product as a monitored quality feature. The analyzed product is manufactured in an eightfold injection mold by injection technology. The products from each injection mold cavity were considered separately. Process capability was assessed using capability indices. Process variability and centering were evaluated. Based on the analysis we can say that the production process is in excellent condition.

Novel method for identifying and diagnosing electric vehicle shock absorber squeak noise based on a DNN

Abstract Suspension shock absorber squeak noise is becoming increasingly apparent within the overall noise level of all-electric vehicles (EVs) due to the extensive reduction in power system noise. Although the early identification of shock absorber squeak noise via bench tests can save costs and time, such identification remains a challenge for the industry. In this paper, a novel method for identifying and predicting EV shock absorber squeak noise is proposed. In contrast to other studies on shock absorber noise that focus on highly complex designs and feature extraction, this study uses the original time signals and frequency spectra to predict the shock absorber squeak noise based on deep neural networks (DNNs). To implement this method, an EV road test is conducted on five different pavements, and the grade evaluation method (GEM) is applied in a subjective evaluation of the annoyance of the shock absorber squeak noise. The vibration signals of the shock absorber piston rod are collected and preprocessed via a bench test. Then, a DNN is developed to automatically extract the shock absorber squeak noise feature and intelligently identify the subjective annoyance (SA) grade of the squeak noise. This novel identification method effectively solves the problem in which the annoyance level cannot be evaluated via the GEM by relying on the rich auditory experience of the evaluation subject. In the validation analysis, the DNN outperforms two other intelligent methods, the genetic algorithm-back propagation neural network (GA-BPNN) and the genetic algorithm-support vector machine (GA-SVM), based on a confusion matrix and an error analysis.

Identification of vehicle suspension shock absorber squeak and rattle noise based on wavelet packet transforms and a genetic algorithm-support vector machine

The squeak and rattle (S&R) noise of a vehicle’s suspension shock absorber substantially influences the psychological and physiological perception of passengers. In this paper, a state-of-the-art method, specifically, a genetic algorithm-optimized support vector machine (GA-SVM), which can select the most effective feature subsets and optimize the model’s free parameters, is proposed to identify this specific noise. A vehicular road test and a shock absorber rig test are conducted to investigate the relationship between these features, and then an approach for quantifying the shock absorber S&R noise is given. Pre-processed signals are decomposed through a wavelet packet transform (WPT), and two criteria, namely, the wavelet packet energy (WPE) and wavelet packet sample entropy (WPSE), are introduced as the feature extraction methods. Then, the two extracted feature sets are compared based on this genetic algorithm. Another advanced method, known as the genetic algorithm-optimized back propagation neural network (GA-BPNN), is introduced for comparison to illustrate the superiority of the newly developed GA-SVM model. The result shows that the WPSE can extract more useful features than the WPE and that the GA-SVM is more effective and efficient than the GA-BPNN. The proposed approach could be retrained and extended to address other fault identification problems.

Sound quality evaluation of vehicle suspension shock absorber rattling noise based on the Wigner–Ville distribution

In this paper, a new sound metric–Sound Metric based on the Wigner–Ville distribution (SMWVD) – was developed toinvestigatetherelationship between subjective evaluations and vehicle suspension shock absorber rattling noise, which substantially affects passengers’ psychological and physiological perceptions. A complete vehicle road test was conducted to measure the interior shock absorber noises, which were subjectively evaluated by 20 jurors. Conventional psychoacoustic indices, i.e. loudness, sharpness, roughness and fluctuation strength, were used to calculate the correlation coefficients between the objective and subjective evaluations, and then, the results were compared with the performance of the SMWVD. The results show that conventional sound metrics have poor relationships with the subjective ratings, while the SMWVD displayed a high correlation of >0.9 between the objective evaluation and the subjective evaluation. These results indicate that the SMWVD can be used to estimate the rattling noise index of a suspension shock absorber without jury evaluation.

Modelling of friction phenomena in sliding conditions in suspension shock absorbers

Friction phenomena are extremely important in the suspension mechanisms used in automotive vehicles. Currently, there is no theory capable of explaining all the friction phenomena from a global perspective. In the case of telescopic hydraulic shock absorbers, the additional contribution of force given by the friction in the range of low damping velocities increases the capability of energy dissipation. In contrast, the continuous transitions between adherence and sliding of the telescopic mechanism diminishes the capability of generating comfort. Moreover, the fluctuations of inner pressures and external side loads have to be added as purely dynamic factors affecting the friction variations. This paper explains the improvements obtained in the modelling of friction phenomena in sliding conditions, by proposing a new formulation of the Stribeck effect and the viscous friction, considering these two effects as associated concepts in the case of the suspension shock absorbers.

Energy Requirements of a Passive and an Electromechanical Active Suspension System

Passive suspensions are designed to dissipate the energy otherwise transferred to a vehicle's body through interactions with a roadway or terrain. A bond graph representation of an independent suspension design was developed to study the energy flow through a vehicle. The bond graph model was tuned and validated through experimental tests and was found to produce suitable results. Examining the bond graph reveals that the dissipated energy associated with vertical and transverse coordinates generally originates from the longitudinal motion of the vehicle and is transferred through the tire-ground contact patch. Additionally, since the longitudinal energy originates from the vehicle's engine, the energy dissipated via the suspension shock absorber as well as other components (e.g., mechanical joints, etc.) essentially dissipate some engine energy. The plots presented in the paper support this theory by showing that upon traveling a rough terrain, the vehicle's longitudinal velocity drops more when vertical vibrations increase. Results show that a vehicle equipped with a passive suspension experiences a larger velocity drop compared to one with an active suspension traversing the same rough terrain. The paper compares the results of simulation of an analytical bond graph model of an active suspension system with experimental results and finds good agreement between the two. Other simulations show that relative to passive suspensions, not only do active suspensions yield substantial improvement in ride quality, they can also result in substantial energy savings. This paper concludes that if electromechanical actuators are supplemented by passive springs to support the vehicle static weight, the amount of energy required for operation of actuators is significantly less than the amount dissipated by conventional shock absorbers.

A superelement model based parallel algorithm for vehicle dynamics

This paper presents a superelement model based parallel algorithm for a planar vehicle dynamics. The vehicle model is made up of a chassis and two suspension systems each of which consists of an axle-wheel assembly and two trailing arms. In this model, the chassis is treated as a Cartesian element and each suspension system is treated as a superelement. The parameters associated with the superelements are computed using an inverse dynamics technique. Suspension shock absorbers and the tires are modeled by nonlinear springs and dampers. The Euler-Lagrange approach is used to develop the system equations of motion. This leads to a system of differential and algebraic equations in which the constraints internal to superelements appear only explicitly. The above formulation is implemented on a multiprocessor machine. The numerical flow chart is divided into modules and the computation of several modules is performed in parallel to gain computational efficiency. In this implementation, the master (parent processor) creates a pool of slaves (child processors) at the beginning of the program. The slaves remain in the pool until they are needed to perform certain tasks. Upon completion of a particular task, a slave returns to the pool. This improves the overall response time of the algorithm. The formulation presented is general which makes it attractive for a general purpose code development. Speedups obtained in the different modules of the dynamic analysis computation are also presented. Results show that the superelement model based parallel algorithm can significantly reduce the vehicle dynamics simulation time.