Hydraulic Tensioner Research Articles

Dynamic Simulation and Test Verification of Hydraulic Automatic Tensioner for an Engine Timing Chain Drive System

As a fundamental component of an automobile engine's timing chain drive system, the hydraulic automatic tensioner significantly enhances fuel economy while minimizing system vibrations and noise. However, there is a noticeable lack of research on automatic hydraulic tensioners. This study presents a comprehensive calculation approach for the principal parameters of a hydraulic automatic tensioner. An effective method, grounded in hydraulics and multibody dynamics, was introduced for estimating the dynamic response of such a tensioner. The simulation model developed for the hydraulic tensioner is characterized by its rapid dynamic response, consistent operation, and high accuracy. The dynamic behavior of the tensioner was analyzed under varying boundary conditions, using sinusoidal signal excitation. It was observed that the maximum damping force increases with a decreasing leakage gap. Conversely, an increase in oil temperature or air content leads to a decrease in the maximum damping force. The reaction forces derived from these calculations align well with experimental results. This calculation and simulation approach offers considerable value for the design of innovative hydraulic tensioners. It not only streamlines the design phase, minimizes the number of trials, and reduces product costs, but also provides robust insights for evaluating the performance of hydraulic tensioners.

Dynamic responses of the active hydraulic pneumatic tensioner for a TLP in internal solitary waves

Tensioner system is the key connection device used to connect the platform and the top tensioned riser. An internal solitary wave (ISW) can cause serious damage to the tensioner system due to rough drift or broken mooring lines. In this paper, an active control tensioner system is proposed under the action of the ISW. By using the coupling model of the Tension Leg Platform (TLP), the dynamic response of the platform with the active tensioner and the passive tensioner under different control modes are studied. It is concluded that the surge/sway and heave motions of the platform are significantly affected by the ISW. Compared with the passive tensioner, the active tensioner obviously reduces the amplitude of the piston rod motion at low frequency and is more stable at high frequency.

Study on dynamic responses of hydraulic pneumatic tensioner for a TLP under hydraulic component failure

This paper takes the hydraulic pneumatic tensioner as the research object. In order to study the dynamic response of hydraulic pneumatic tensioner, a coupled model of tension leg platform was established. Three kinds of sea conditions including first-order irregular wave, second-order wave and freak wave are simulated. The dynamic response of the hydraulic pneumatic tensioner is analyzed under the action of different pressure accumulators. It is found that the greater the pressure of accumulator, the smaller the displacement of hydraulic cylinder and the greater the tension under the action of the second-order wave force and the freak wave force. In the second-order waves, the average drift force has great influence on the amplitude of displacement and tension of hydraulic cylinder, while the second-order sum frequency force has great influence on the frequency of displacement and tension of hydraulic cylinder. In addition, the dynamic responses of the tensioner under second-order waves are also studied when one cylinder fails. When one cylinder fails or is in semi-failure state, the hydraulic pneumatic tensioner can still provide a nearly constant tension to the riser. The remaining normal piston cylinders’ tensions will increase, but the total tension will decrease.

Design and Analysis of a Compact Hydraulic Bolt Tensioner

In equipment like high pressure vessels, there will caps on which loads of the order of several thousands of tons acts. Such caps require a huge number of big-diameter bolts, often M70 to M150mm in diameter. Each bolt will be subjected to a tremendous amount of force, on the order of 300 tons. The use of hand-operated wrenches to apply such a load is deemed out. When a high number of bolts are tightened on the flange, the applied load is lost owing to friction at the clamping surface and the applied load is not uniform. It is advised that a hydraulic bolt tensioning system be used to address these drawbacks. The device operates at a pressure of 1500 bar, which is extremely high. Therefore, the equipment must be designed to ensure the device’s compactness and safety. Bolt tensioners are used to tighten bolts and studs in a variety of important applications. These devices would be imported. It was proposed in this work that a small hydraulic bolt tensioner be designed and analysed using both theoretical and finite element analysis (Non-liner static analysis). The required boundary conditions and applied pressure were computed. The tensioner’s design was optimized to assure its safety and compactness.

Bolted Joint Tightened by Hydraulic Tensioner

Bolted Joint Tightened by Hydraulic Tensioner

Study on calibration method of hydraulic bolt stretcher

Bolt hydraulic tensioner is ideal equipment for bolt fastening and disassembly. Compared with traditional method, it has incomparable advantages. Bolt hydraulic tensioner has been widely used in wind power, nuclear power, aerospace, steel, petrochemical and other major fields. In this paper, two methods of calibrating the hydraulic stretcher are proposed, and the problems that should be paid attention to in the process of calibrating the stretcher are analyzed in detail, it can be used for reference in the calibration of hydraulic stretcher.

Structural response analysis of the hydraulic pneumatic tensioner under its local failure based on a fully coupled TLP-TTR system

The presented work studied the structural response of the hydraulic pneumatic tensioner (HPT) in a TLP-TTR system with failure of the tensioner cylinder. A fully coupled hull-tendon-TTR-tensioner model was established in AQWA to simulate the failure numerically. A specific HPT was modeled by considering 4 cylinders and the real-time stroke of each piston. A set of formulas was proposed to calculate the real-time tension including different components, e.g. Stribeck friction, in the tensioner. A riser array including 6 independent production TTRs and their tensioners was also modeled. The production TTR model was stacked up by different specific riser joints. The hydrodynamic force acting on the hull was obtained by using the 3D potential flow theory. The real-time tensions on different tensioner cylinders were obtained by using an in-house-developed program. Different environmental conditions, including a calm sea, regular waves, and extreme sea states, were considered in the simulations. In the results, the behaviors of different cylinders of the failed tensioner were presented. The results show that when an accidental local failure of the HPT occurs, the tension and stroke responses are still far from the designed-limits to induce a progressive failure.

Estimation method for axial tension of various bolted joints using hydraulic tensioner

Estimation method for axial tension of various bolted joints using hydraulic tensioner

ИССЛЕДОВАНИЕ ПАРАМЕТРОВ РАБОТЫ ГАЗОРАСПРЕДЕЛИТЕЛЬНОГО МЕХАНИЗМА ПРИ ВИБРОАКУСТИЧЕСКОМ КОНТРОЛЕ В РЕЖИМЕ ТЕСТОВОГО ДИАГНОСТИРОВАНИЯ

Statistical analysis of ICE system faults shows a considerable growth of gas distribution mechanism failures: on average 7-12 %.This is explained by complicacy of gas distribution elements and occurrence of numerous new elements ( hydraulic pushers, hydraulic tensioners, automatic correcting mechanism of gas distribution phases, multivalve systems). However, in practice improvement of the gas distribution mechanism conspicuously surpasses development of new veracious techniques and methods of technical condition control. Development of new techniques and methods of technical condition control over the gas distribution mechanism enables solving of the important task to increase the engine operational resource. The most informative and veracious diagnostic method is vibroacoustic one, which makes it possible to evaluate technical condition of gas distribution mechanism at any stage. In order to diagnose the gas distribution mechanism with consideration of minimum interference and maximum information content, we chose the equipment which includes USB-Avtoscope III (Postolovsky oscillograph), a laptop with data analysis software, a pressure sensor for pressure control in the cylinder and an accelerometer. For prevention of linear expansion of metals , diagnostics was made on the engine with the temperature ranging from +80 to +90° C (measurements which are taken by a measuring probe within this temperature range are identical). The maximum expansion of metal was fixed at 1100 min-1 in 14 sec., at 1300 min-1 - 13 sec., at 1500 min-1 - 10,2 sec. Change of valve expansion clearance from 0,35 mm to 0,7 mm reduces the valve opening phase by 2×15°30′ (i.e. results in considerable delay of valve opening by 15°30′ and acceleration of its closure by 15°30′).

Detection and Change of Tension Forces Operating on Elevator Hoist Ropes

The Decree on Technical Requirements for Buildings stipulates that all the new residential buildings with entrances to flats at the fifth and higher floors, or attics at the same level, must have an elevator installed. The applicable standards in the Czech Republic so that, for the electric elevators with friction discs that use two or more hoist ropes, the weight of the applied load was evenly distributed over all the cross-sections of the hoist ropes for the given layout of the elevator. Rope tension equalizers used in elevators are usually designed to allow sensing of the acting tensile forces in an uninterrupted cross-section of the hoist cable. They are usually installed on hoist ropes only in the newly-installed elevators and during regular inspections. The paper describes the basic principles of devices currently in use, the so-called rope tensioners, which allow detecting and adjusting primarily different tensile forces in the hoist ropes to the same value. The paper refers to two, already published design variants of portable rope straighteners, which use foil strain gauges or strain gauge sensors to detect the acting tensile forces in the hoist ropes. The constructional solution and the principle of operation of the “hydraulic rope tensioner”, which were created at the VŠB-Technical University of Ostrava, are described in more detail.

Characteristics of various bolted joints by using hydraulic tensioner

Characteristics of various bolted joints by using hydraulic tensioner

Estimation about bolt tension under repeated tightening by using hydraulic tensioner

Estimation about bolt tension under repeated tightening by using hydraulic tensioner

Evaluation about decreasing of bolt tension under repeated tightening by hydraulic tensioner

Evaluation about decreasing of bolt tension under repeated tightening by hydraulic tensioner

Research about vibration characteristics of timing chain system based on short-time Fourier transform

Vibration characteristic of timing chain system is very important for an engine. In this study, we used a bush roller chain drive system as an example to explain how to use mulitybody dynamic techniques and short-time Fourier transform to investigate vibration characteristics of timing chain system. Multibody dynamic simulation data as chain tension force and external excitation sources curves were provided for short-time Fourier transform study. The study results of short-time Fourier transform illustrate that there are two main vibration frequency domain of timing chain system, one is the low frequency vibration caused by crankshaft sprocket velocity and camshaft sprocket torque. Another is vibration around 1000Hz lead by hydraulic tensioner. Hence, short-time Fourier transform method is useful for basic research of vibration characteristics for timing chain system.

Optimal tightening process of bolted joints

Threaded fasteners were developed long time (let’s remember that Archimedes – 287-212 BC – invented the water screw). Nowadays, bolted joints are used in almost all sectors of the industry. But in spite of having been an important machine part for centuries, problems may be encountered with them. They are so common that they are taken for granted and too often, not analyzed as deeply as it should be. The wrong tightening is one of the most frequent causes of ductile rupture and by far the most frequent cause of fatigue failure. The tightening operation is never easy. It is necessary to pay particular attention to the choice of the tightening tool, the process and the control method. The tightening operation may itself cause damage on parts. The tightening load must not be too low, or excessive or not equally distributed among the bolts. These three defects can even be made on the same bolted joint! This impacts badly the performance of the assembly and leads to a shorter lifespan. If insufficient precautions are taken, the real tightening preload on all the bolts will not fit well with the requirements and would be badly distributed. Consequently, the practical conditions are quite different from the hypothesizes which are taken for the initial calculations (analytics or FEM) at the design stage. Thus, the results of the calculations of bolted joints cannot be considered as accurate and reliable. Practically, there are several means to tighten a bolt. The two ways most frequently used are torque wrench and hydraulic bolt tensioner. Torque wrench involves exerting a torque to the bolt head or the nut. Hydraulic bolt tensioner applies a traction load directly on the bolt. It is well known that bolt tensioners give better accuracy and homogeneity in the final tightening load than the torque method, but the tension load applied with the tensioner must be higher than the final remaining tightening load. So, the paper focusses on the hydraulic tensioner to show how the tightening load can be obtained from the applied tension load and to propose a way to optimize and secure the tightening process. However, for the reasons above mentioned it appears necessary to first make a general description of technical aspects of bolted joints. What really happens when tightening with torque wrench or with bolt tensioner is explained.

Estimation about axial tension of bolted joint by using hydraulic tensioner

Estimation about axial tension of bolted joint by using hydraulic tensioner

油圧テンショナを用いたボルト締結体の有限要素解析と軸力評価

油圧テンショナを用いたボルト締結体の有限要素解析と軸力評価

Vibration and noise source identification methods for a diesel engine

In this study, we used a four-cylinder inline diesel engine as an example to explain how to use test methods and multi-body dynamic techniques to identify the exact source of noise and vibration. A 1 meter noise test was conducted to indicate that the engine front end is the main source of noise. The near-field sound intensity method and the near-field acoustic holography technique were used to identify the chain drive system as the source of noise and vibration. A 3D dynamic analysis model of the timing chain drive system was established using RecurDyn software. Results of the analysis show that the hydraulic tensioner is incompatible with the timing drive system of the bush roller chain. Hence, the timing chain system causes a loud noise and strong vibration. Some strategies on how to optimize the timing chain drive system are presented at the end of this paper.

Research on 3D loading system for ITER gravity support prototype

The objective and importance of structural performance tests for the ITER gravity support prototype were described. The model of the gravity support system was established. Based on the analysis of loads, the torque transformation method and the 3D loading method for prototypes under complex load conditions were proposed. The proposed methods overcome 3D loading problems in the case of the complex load cases. The structural design schemes of the mixed 3D loading system with hydraulic bolt tensioners and the 3D loading system with bidirectional hydraulic cylinders were discussed. Two design schemes were compared and analyzed. Based on the finite element method, the numerical analysis of the 3D loading framework for bidirectional hydraulic cylinders was done. Results show the proposed 3D loading system meets the performance test requirements of the ITER gravity support prototype and should be preferred for the prototype loading experiment.

Prototype Engineering Test Platform of ITER Magnet Gravity Support

ITER magnet gravity support (GS) has been redesigned as a structure of pre-assembled multi-flexible plates instead of the original welded structure. In the past several years, engineering tests of the new structure have been proposed. A prototype engineering test platform is being developed. In order to apply the loads/load combinations onto the test mock-up, seven hydraulic bolt tensioners in three directions have been applied to simulate various loads (forces and moments), through which the deformation of bolts, flexible plates and clamp blocks, the stress distribution in the flexible plates, the friction between the contact surface, etc. can be monitored/tested. The measurement and control system includes seven sets of synchronization controller, a 16-channel strain gauge, 25 sets of displacement sensors, etc. Principles of EDC220 digital controller and development of multi-channel control software are also demonstrated.