Hydraulic Damper Research Articles

Design and control performance optimization of dual-mode hydraulic steering system for wheel loader

The traditional wheel loader performs the steering operation by the rotation of the steering wheel, which significantly increases the complexity and fatigue of the operator. This paper presents a dual-mode steering system to solve the afore-mentioned problems, where a pilot control valve with a joystick is connected in parallel with the redirector to control the hydraulic steering system. The steering speed and angle of the loader can be controlled by the swing angle and time of the joystick. Based on the simulation and experimental results, the proposed system has the same trend of pressure variation and good steering performance compared with the traditional steering system. The hydraulic damping diameter matching the steering system is obtained by simulating and optimizing the equivalent model. The experimental results show that the effective control swing angle of the joystick increased from 12.5° to 19.7°, which improves the control accuracy of the steering system.

Reducing wheel–rail surface damage by incorporating hydraulic damping in the Bogie primary suspension

ABSTRACT Wheel–rail surface damage in curves can be effectively reduced with a lower vehicle Primary Yaw Stiffness (PYS), while lowering PYS is detrimental to ride comfort and vehicle stability. This trade-off can be addressed by integrating hydraulic damping into primary suspension. However, work in this area only concentrated on comparing the effects of specific devices – the full potential of the hydraulic-damping-integrated primary suspension on combating the trade-off considering the whole parameter space is still unknown. Here we address this by making the following two contributions: (1) fully exploring the potential of hydraulic-damping-integrated primary suspension, on minimising the PYS while maintaining ride comfort; (2) systematically investigating the trade-off between the PYS reduction and suspension stroke requirement. Based on a case study using the Mark 4 Coach, this paper found that the optimal hydraulic-damping-integrated suspension can reduce PYS by 97% over the default without worsening comfort. This large reduction can potentially lead to a significant lifetime wheel-rail maintenance cost saving of approximately £42M for the fleet. If a larger suspension stroke is allowed, more cost saving can be achieved. These results provide motivation to conduct detailed engineering design studies to further examine the trade-off between financial benefits and design complexity.

Vibration damping performance of the electrohydraulic self-leveling unit of the tracked platform of robotic bricklaying combine

The study proposes the use of a semi-active hydro-pneumatic spring damper unit for damping pressure pulsations in the servohydraulic leveling system of an electrohydraulic self-leveling unit of a tracked platform of a robotic bricklaying combine (RBC). The semi-active hydro-pneumatic spring damper unit consisted of a gas spring in the hydro-pneumatic accumulator and a controlled hydraulic damping valve. A model of a hydro-pneumatic accumulator with a connection tube was presented, using lumped hydraulic elements in the form of resistance, inductance, and capacitance (RLC). This model was transformed into a form of frequency impedance, from which the amplitude and phase characteristics were determined. The complex impedance of the throttle valve was determined, in which the real part is resistance and the imaginary part is reactance. Finally, the damping performance characteristics of a semi-active hydro-pneumatic spring damper unit were analyzed.

Application of elastically protected hydraulic vibration damper in spring suspension of locomotives

Introduction. In the undercarriage of modern locomotives hydraulic vibration dampers are widely used to dampen vertical vibrations that occur in the axlebox stage of the spring suspension. Their resistance force is directly proportional to the deformation rate of the spring set. High levels of vibration frequencies and amplitudes in the axlebox stage lead to a significant increase in the strain rate and dissipative forces, which causes frequent failures of hydraulic vibration dampers. Therefore, issues related to improving the performance of axlebox hydraulic dampers are actual.Materials and methods. In order to evaluate the effectiveness of elastically protected hydraulic vibration damper in axlebox suspension, the authors studied the vibrations of a simplified model of a 2ES5K electric locomotive with a typical layout of the axlebox stage of spring suspension and a circuit with an elastically protected hydraulic vibration damper. The authors used a high-frequency random process as a kinematic perturbation of vibrations. The system of differential equations was solved in the MatLab — Simulink software package by numerical integration using the Runge — Kutta method of the fourth order. As a result of the solution, realisation of stationary and ergodic random processes were obtained. Results. The comparison of the obtained characteristics of random processes of vibrations of these two options showed that the use of an elastically protected axlebox vibration damper significantly reduces the frequency range and amplitudes of dissipative forces, which ensures a reduction in the number of axlebox damper failures and an increase in the number of runs before replacement is required.Discussion and conclusion. The shown efficiency of using an elastically protected axlebox vibration damper allows increasing the reliability of the damper. In order to determine the distance run between overhauls, it is necessary to carry out a controlled operation cycle or test the prototype axlebox assembly with the elastically protected vibration damper and measure the parameters of such assembly.

Energy Efficiency of Pressure Shock Damper in the Hydraulic Lifting and Leveling Module

This study evaluates the energy efficiency of pressure shock damping in a hydraulic lifting and leveling (HLL) module of a mobile robotic bricklaying system (RBS). The HLL module includes a servohydraulic actuator (SHA) and a hydraulic shock damper (HSD). The proposed adjustable HSD consists of a hydraulic accumulator circuit (HAC) and proportional damping valve. The frequency characteristics of the impedance and damping efficiency indices were used to evaluate the effectiveness of HSD damping. The dynamic responses of the SHA with and without HSD were analyzed based on a nonlinear state-space model. To control the damping of the pressure shock in the SHA-HSD system, a linear quadratic Gaussian (LQG) controller that follows two measurement signals was implemented. The LQG controller was adapted to the specific dynamic requirements of the SHA-HSD control system and nature of the RBS shock loads. The effectiveness of the LQG controller was evaluated during RBS operation under laboratory conditions. The main purpose of this study was to dynamically stabilize a leveled robot base subjected to shock loading during automatic operation of the RBS.

New running gear for improving the lateral dynamic characteristics of rubber-tired light rail vehicles

Rubber-tired light rail vehicles are generally operated on lines which include a number of small curves, steep slopes, or track switching sections to reduce construction costs or to place multiple stations in densely populated areas. Recently, the tendency is to increase acceleration, deceleration, and operation speed to shorten travel time and to increase transportation capacity. These track characteristics and operation patterns may result in deteriorating lateral dynamic characteristics in rubber-tired light rail vehicles. Therefore, running gear in rubber-tired light rail vehicles needs to play a role in effectively damping lateral vibrations and shock transmitted from the guidance rails through the guidance wheels. In this paper, new running gear was proposed to improve the lateral vibration and ride comfort in rubber-tired light rail vehicles. The new running gear has been newly installed with lateral rubber shock absorbers that can dampen lateral vibration on curved routes. In addition, it has been installed with a bi-directional return spring in place of the existing restoring coil spring and hydraulic damper to improve lateral vibration on straight routes. The effect of improving the lateral dynamic characteristics of the new running gear was verified through dynamic analysis and actual vehicle driving tests (field tests).

Primary suspension failure analysis in FIAT type LHB bogies and life estimation

Multiple cases of failure in the primary suspension system of LHB coaches were reported in specific light-weight passenger coaches recently. Frequent failure in suspension systems led to increased downtime and maintenance costs. Failure was associated to fatigue in primary helical springs and was found to be preceded by failure of hydraulic dampers. We present a study on analysis of these failures and suggest design modifications for enhancing fatigue life. A flexible finite element model of the bogie, with suspension system involving flexible helical springs, is developed and simulated for typical load and vehicle speed parameters. Conditions of damper failure are incorporated and the exact location of failure and the observed fatigue life of spring are validated. Loading on the bogie involves tare weight and rail-wheel contact forces. Rail-wheel contact forces are computed through multibody dynamic model for typical track irregularity data. Linear static analysis is done to obtain stresses under steady loads. This is followed by pre-stressed modal analysis and harmonic response simulation of the flexible model of the bogie. Fatigue life computation under combined static and alternating load conditions is done by employing the Modified Goodman diagram. Iterative modifications in design of the primary suspension springs are carried out. Minimal changes, which do not require change in the designs of associated components or change in the manufacturing set-up, are suggested. Modifications are validated through comparative fatigue life estimation.

Modeling Method of Dynamic Characteristics of Hydraulic Damping Rubber Isolator

<div class="section abstract"><div class="htmlview paragraph">The dynamic characteristics of hydraulic damping rubber isolators (such as hydraulic bushing and hydraulic mount) are related to excitation amplitude and frequency. Based on the lumped parameter model of hydraulic damping rubber isolator, a unified linear model of complex stiffness is derived and its deficiency is pointed out. Based on the derived linear model, this paper considers the nonlinear damping of inertia channel and the nonlinear stiffness of the upper chamber of the hydraulic damping rubber isolator, so as to establish a new nonlinear model, which can reflect the amplitude and frequency dependence of the dynamic characteristics of the hydraulic damping rubber isolator. Finally, the nonlinear model is used to analyze the dynamic response of hydraulic damping rubber isolator under harmonic excitation and random excitation respectively, and the results are compared with the test results. The results show that the proposed model can characterize the amplitude and frequency dependence of the dynamic characteristics of the hydraulic damping rubber isolator, and can accurately calculate the dynamic response of the hydraulic damping rubber isolator under harmonic excitation and random excitation.</div></div>

A new hydraulic damper dynamics model and the availability on high speed vehicle dynamics investigation

The function of the hydraulic damper of the high-speed Multi-Electric-Units (EMUs) is to offer viscous damping to reduce the vibrations and to keep the stability of the vehicle. It is the key component and it has great effects on the high-speed EMU dynamics. A new hydraulic damper dynamics model including two clamping points stiffness, a viscous damping and two centralised masses, is presented in this paper. A high-speed vehicle–track interaction dynamics model is developed, in which the new hydraulic damper dynamics model is introduced in it to investigate the damper and vehicle dynamics. With numerical simulation, the clamping point loads and damping forces of four types of dampers of the vehicle are obtained. The reliability of the new damper dynamics model is validated with comparison between the simulation results and the field test results. The availability of the new damper dynamics model is confirmed with the comparison of the results between a simplified damper dynamics model and the new damper dynamics model for two types of high-speed EMUs in China. With the help of the new damper dynamics model, the optimised clamping point stiffness of the dampers and the effect of the damper mass on the vehicle system dynamics are discussed. The investigation results show that the vibration difference between the damper and the connected components of the vehicle could be obtained.

A physical model-neural network coupled modelling methodology of the hydraulic damper for railway vehicles

The dynamic characteristics of the hydraulic damper are time-varying in the complex working environment. To reveal the internal influence mechanism of the boundary conditions on the dynamic performance of the hydraulic damper and take it into account in the multi-body dynamics calculation, the laboratory test of the hydraulic damper is carried out firstly, and it is confirmed that the hydraulic damper has significant frequency-dependent and amplitude-dependent and temperature-dependent characteristics. Then, combining the physical parameter model with the neural network model, an accurate hybrid neural network model of the hydraulic damper is proposed. The physical parameter model considers the damper structure, including orifice, damping valve, rubber joint and the relationship between temperature and viscosity of hydraulic oil. The neural network model describes the personality characteristics of the hydraulic damper, such as oil leakage, the internal friction force and the percentage of entrapped air in oil. Finally, the responses and the dynamic parameters of the hybrid neural network model are calculated and compared with the experimental results by considering various exciting amplitudes and frequencies. The results show that the proposed model can fully simulate the dynamic performance of the hydraulic damper under various operating conditions.

Adaptive stability mechanism of high-speed train employing parallel inerter yaw damper

The aim of the study is to design a secondary yaw suspension that will control both low-frequency body motion and bogie hunting under different wheel–rail equivalent conicities. In order to enable the high-speed train to adaptively adjust to different wheel tread wear stages and improve the lateral dynamic performance of the vehicle in extreme wheel–rail contact states without any sensors and control systems, the eddy current damper with the parallel inerter as the yaw damper is proposed, and the in-depth research on its working mechanism is conducted. By establishing the theoretical analysis model of the lateral dynamics of high-speed train, and the multi-objective optimisation of the vehicle performances is carried out. The optimal parameters of the yaw damper under different wheel–rail contact conditions are analysed and the importance of frequency-dependent stiffness of yaw damper is obtained. Based on the characteristics of high-frequency transmissibility of inerter, the parallel inerter is applied to solve the limitation of insufficient dynamic stiffness of the traditional hydraulic yaw damper. The parameter configuration of the yaw damper with small series stiffness and large parallel inerter is proposed, and the stable operation of trains in major wheel–rail contact equivalent conicity is realised by using its frequency-dependent stiffness characteristics. In addition, the optimal energy dissipation and negative stiffness conditions of the parallel inerter yaw damper are analysed in this paper.

Improving the damping of vehicle vibration by improving pneumatic springs

It is known that the air suspension of vehicles, in which diaphragm-type air springs are used as an elastic element, do not provide the necessary vibration damping. The reason for this is that such air springs have a relatively large passive part. As a result, a relatively small mass of compressed air crosses through the throttle installed between the air spring and the additional reservoir. This mass of air contains thermal energy, into which the energy of vibrations, which enters through the walls of the additional reservoir into the environment, has turned. This is interpreted as vibration damping, which is insufficient due to the low air mass. Therefore, hydraulic vibration dampers are installed parallel to the diaphragm air springs, which complicates and increases the cost of the vehicle. Increasing the damping properties of such air suspensions could eliminate these hydraulic vibration dampers, which would reduce costs and simplify operation. An air suspension with an improved air spring has been proposed, which has an increased effective area and a reduced "passive" capacity, an empirical formula has been built to determine its damping coefficient, as well as an expression for the stiffness coefficient. Mathematical modeling of oscillations of vehicles with different designs of pneumatic springs was carried out in order to improve their damping. The mathematical model takes into account the change in the parameters of the air spring during vibrations. The study was carried out for the diesel train DL-02. Using mathematical modeling, the effectiveness of the air suspension with an improved air spring has been proven: its damping index reaches 0.263, and the vibration damping coefficient is 45,859 kg/s, which corresponds to the values ​​​​recommended for vehicles.

The effect of various damping on the isolation performance of quasi-zero-stiffness system

A quasi-zero-stiffness (QZS) vibration isolation system was designed to attenuate low-frequency and ultra-low-frequency vibrations. Because nonlinearity exists in QZS systems, various nonlinear dynamic behaviours inevitably influence the vibration isolation performance. Thus, damping is the key for suppressing nonlinear effects. The effects of three types of damping, viscous damping, hysteretic damping, and nonlinear hysteretic damping on the QZS vibration isolator are discussed in this paper. The Duffing-Ueda equation was used to describe the dynamic motion of the QZS system, which was solved using the harmonic balance method (HBM). Two hybrid-damping models were then proposed to avoid unbounded nonlinear responses for excessive base excitation. Based on theoretical and numerical analysis, the effect of the two hybrid damping models, the hysteretic-nonlinear hysteretic (H-NH) damping model and viscous-hysteretic-nonlinear hysteretic (V-H-NH) damping model, on the transmissibility is discussed in detail. To verify the theoretical results, QZS isolator prototypes with two types of hybrid damping were designed and manufactured. A hydraulic damper and a thermoplastic rubber (TPR) damper were used respectively in the two models of the experiments. The experimental results reveal that the isolator with hybrid linear and nonlinear damping provides a better isolation effect for both low-and high-frequency vibrations.

Design and Simulation Analysis of an Electromagnetic Damper for Reducing Shimmy in Electrically Actuated Nose Wheel Steering Systems

Based on the technical platform of electrically actuated nose wheel steering systems, a new type of damping shimmy reduction technology is developed to break through the limitations of traditional hydraulic damping shimmy reduction methods, and an electrically actuated nose wheel steering structure scheme is proposed. The mathematical model of the electromagnetic damper is established, the derivation of skin depth, damping torque and damping coefficient is completed, and the design of the shape and size of the electromagnetic damper is combined with the derivation results and the technical index of shimmy reduction. The electromagnetic field finite element simulation results show that the mathematical modeling method of the electromagnetic damper has good accuracy, and its application to the shimmy reduction module of the electrically actuated nose wheel steering system is also feasible and superior. Finally, the key factors influencing the performance of electromagnetic damper shimmy reduction are studied and analyzed, thus forming a complete electromagnetic damper shimmy reduction technology for the electrically actuated system, and laying the foundation for the design of novel all-electric aircraft and landing gear.

Semi-Active Cable Damping to Compensate for Damping Losses Due to Reduced Cable Motion Close to Cable Anchor

The relative motion of transverse cable dampers is smaller than predicted by the taut string model because of the effects of bending stiffness and fixed support conditions. As a result of the reduced damper motion, the dissipated energy per cycle is reduced as well, which may explain why damping measurements on real stay cables with transverse dampers often show lower cable damping ratios than expected from the taut string theory. To compensate for the reduced damper motion and damper efficiency, respectively, a semi-active cable damper is proposed. The controllable damper is realized by a hydraulic oil damper with real-time controlled bypass valve whereby the resulting damper force is purely dissipative. The proposed control law is clipped viscous damping with negative stiffness. The viscous coefficient is adjusted in real time to the actual frequency of vibration to generate optimum modal damping while the negative stiffness component partially compensates for the reduced damper motion due to the flexural rigidity and fixed support conditions of the cable. The measurements of the prototype semi-active hydraulic damper are used to derive a precise model of the semi-active damper force including the control force constraints due to the fully open and fully closed bypass valve. This model is used to compute the cable damping ratios of the first four cable modes, for typical damper positions, for a taut string model and for a cable model with flexural rigidity and fixed supported ends. The obtained cable damping ratios are compared to those resulting from the passive linear viscous damper being optimized to the first four cable modes. The results demonstrate that the proposed semi-active cable damper with the consideration of the minimum and maximum control force constraints significantly enhances the cable damping of the first four modes compared to the linear viscous damper.

Design and Development of Electromagnetic Suspension for a Two-wheeler

Traditional hydraulic damper has limited response to different road conditions. This makes it difficult to use in places where roads are not developed. This research focuses on the design and development of a suspension system for two wheelers using electromagnet. This idea increases the response range of the damper of the suspension system. The suspension design is based on maximum load carrying capacity of 80 kg and maximum damper travel of 6 inches. Various technologies of electromagnetic suspension were analysed and simulated. Suspension model simulation and data interpretation were performed and the results are discussed.

Dynamics of the Rolling Stock and the Choice of Parameters of Vibration Dampers

Modern railway rolling stock should meet requirements regarding comfort (maximum travel speed with minimum vibrations of wagons, noiselessness of movement, etc.).To eliminate the influence of dynamic loads, rolling stock is equipped with vibration dampers. The objective of the work is to select the parameters of the vibration dampers of rolling stock, depending on its characteristics, to ensure the due indicators of comfort and safety of transportation of passengers and goods by rail. To achieve this objective, applied methods of mathematical modelling were based on numerical programming of operation of dynamic systems. The indicators of vibration dampers are evaluated according to the results of studies of the dynamics of the rolling stock (in particular, of vibration protection rates).Assessment of dynamic state of the rolling stock implies application of methods of mathematical and physical modelling, which include the development of a physical and mathematical model, a calculation algorithm, and computer programming. The study of the mathematical model by numerical methods makes it possible to carry out a multifactorial experiment using a large number of input parameters (factors) and to select the characteristics of vibration dampers that are optimal for the conditions under consideration.To solve dynamic problems, the harmonic perturbation model, which is the most widespread, was specified in the form of a sinusoid with a period corresponding to the rail length.A quantitative assessment of the vibration process (frequency, amplitude) makes it possible to identify the main processes occurring in the system under consideration under various types of external load. The introduced assumptions related to rigidity, mobility and geometric immutability of the system allow determining the methods for obtaining a mathematical model and considering the vibrations as flat ones.The equations were solved in MathCad Prime 4.0 package using the Runge–Kutta method with automatic step selection. The subsequent study of the properties of the dynamic system was carried out by changing the resistance parameter of dampers of the first stage of spring suspension, while recording the values of the amplitude of the vibrations of the system and the period.The analysis of the results has shown that the vibration period of the body and bogies under any changes in the resistance parameter of the damper remains unchanged, while rational parameters of resistance of axle box dampers have been revealed for specified indicators. Hydraulic vibration dampers with the revealed parameters used on rolling stock help to reduce wear and damageability of running gears, improve ride comfort and traffic safety, as well as to reduce repair and maintenance costs.

Analysis of the influence of the hydraulic vibration damper characteristics on the stress-strain state of the passenger car trolley

Analysis of the influence of the hydraulic vibration damper characteristics on the stress-strain state of the passenger car trolley

Investigation on Fretting Wear Performance of Laser Cladding Wc/Co06 Coating on 42crmo Steel for Hydraulic Damper

Investigation on Fretting Wear Performance of Laser Cladding Wc/Co06 Coating on 42crmo Steel for Hydraulic Damper

PRINCIPLES OF CONSTRUCTION OF THE GENERALIZED MATHEMATICAL MODEL OF THE HYDRAULIC EXTINGUISHER OF OSCILLATIONS OF THE PASSENGER CAR

The study of the processes associated with the use of working fluids in the elements of hydraulic drives was preceded by studies of the unsteady periodic movement of the working fluid in the pipelines of hydraulic systems. Such processes take place in hydraulic drives and their elements, and are associated with the compressibility of the working fluid. The stability of the operation of hydraulic valves, which are supplied to hydraulic systems in order to maintain, within the required limits, pressures or flow rates, is also largely predetermined by non-stationary hydro mechanical processes occurring in the pipelines of these systems, channels and chambers of hydraulic devices. The peculiarities of the working processes of passive vibration dampers of passenger cars include the interaction of the working fluid with moving parts and its flow through the channels and through the calibrated holes with local artificial resistance. For in-depth analysis of changes in operating parameters, it is necessary to use a mathematical model that should reflect the processes that occur during the operation of the hydraulic device. In the presented article the generalized mathematical model of the hydraulic damper of fluctuations of the passenger car of the НЦ-1100 type is developed. This model takes into account the special operating conditions of the hydraulic shock absorber, which allows you to study the impact of operating parameters on the performance of the device.