The methods for diagnostics of the hydraulic system proposed in the article describe in sufficient detail and clearly the procedures for finding, identifying and eliminating malfunctions in the hydraulic system of an excavator and can serve as a practical guide for enterprises operating equipment with a hydraulic drive

Maintenance of hydraulic systems of machines should be carried out by highly qualified specialists using high-precision diagnostic devices that display information about problems on a computer. The latter should indicate methods of troubleshooting. This approach is increasingly being used.

However, even if there is no competent specialist nearby, and only simple measuring instruments are available from the diagnostic tools, it is possible to determine the causes of a hydraulic system malfunction quite accurately and quickly using a logical method of finding them. At the same time, it is necessary to understand well the basic principles of hydraulics and to know the basics of operation and structure of each element of the hydraulic drive.

How do I stop the excavator?

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If a malfunction has resulted in the loss of functions of the machine, and / or adversely affects the safety of its operation, or damages the environment (for example, breaking the high pressure hose), the machine must be stopped immediately.

To ensure safety when stopping the machine, the following measures must be taken:

• lower all suspended working parts of the machine or fix them mechanically;
• relieve pressure in the entire hydraulic system;
• discharge all accumulators;
• relieve pressure from pressure transducers;
• turn off the electrical control system;
• disconnect the power supply.

It should be borne in mind that the working fluids used in hydraulic drives are low-compressible in comparison with gas and expand slightly when the pressure decreases. However, in those places of the hydraulic system where compressed gas can be located (due to insufficient deaeration or when a hydraulic accumulator is connected), the pressure should be reduced very carefully.

How to approach hydraulic system diagnostics?

Hydraulic system faults can be divided into two types:

• malfunctions that do not affect (of course, up to a certain time) on the functioning of the machine - functional malfunction in the hydraulic system (for example, increased leakage, temperature, etc.);
• faults affecting the function of the machine - a functional problem in the machine (for example, reduced performance).

The search for different types of faults is performed according to different algorithms.

There may be cases where the same malfunction (for example, of a pump) can lead to a functional malfunction in both the machine (reduced performance) and in the hydraulic system (increased noise level).

Experience has shown that it is preferable to start troubleshooting with the underlying problems and work through test procedures, taking into account such indications as temperature rise, noise, leaks, etc., as "clues". Common sense is critical, as certain symptoms can directly indicate a problem area. The jet of oil flowing out from under the hydraulic cylinder seal indicates where the problem area is.

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However, some of the symptoms are not so obvious. If in any node there is a flow leakage during the transition from high pressure to low pressure, then local heat release occurs in it, which is not always possible to detect immediately.

Wherever you start your search, certain questions need to be answered before you can act. If there is a report of a problem, then it is necessary to collect as much factual information as possible. Perhaps this problem has already occurred and is recorded in the operating documents. In this case, you can save a lot of time. Check to see if any maintenance or adjustment work has been carried out on the system shortly before the malfunction occurs. It is necessary to determine the exact nature of the malfunction: it appeared suddenly or developed gradually, over a long time, on the operation of which parts of the machine it affects.

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How to identify the simplest hydraulic system faults?

There are two ways to identify faults:

• with the help of the senses;
• using devices and tools.

The simplest faults in a hydraulic system can be detected with the help of the senses - by seeing, feeling, hearing - and very quickly. In practice, many problems are solved in this way, without the use of any tools.

If with the help of the senses it was not possible to identify the malfunction, then it is necessary to use devices: manometers, flow meters, etc.

How to approach the search for more complex hydraulic problems?

Before starting troubleshooting, you need to clearly know which parameters of the hydraulic system must be measured in order to obtain information about the location of the malfunction, and with what special tools, devices and equipment to do this.

Measured parameters

For the normal operation of the machine, a certain force (torque) must be transmitted to its working body at a certain speed and in a certain direction. The compliance of these parameters with the specified ones should be provided by the hydraulic drive, which converts the hydraulic energy of the fluid flow into the mechanical energy of the output link. The correct operation of the working body depends on the parameters of the flow - flow rate, pressure and direction.

Therefore, one or more of these parameters must be checked to test the hydraulic system. To make a decision on which parameters to check, it is necessary to obtain complete information about the malfunction.

Often the message about a malfunction in a car consists of rather inaccurate information, for example: "insufficient power". The power depends both on the effort on the output link and on its speed, i.e. from two parameters. In this case, more focused questions should be asked to decide which parameter to check: Is the drive running too slowly or is it not delivering the required force or torque?

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After determining the nature of the malfunction (insufficient speed or force, wrong direction of movement of the working element), it is possible to determine the deviation of which flow parameter (flow rate, pressure, direction) from the required value led to this malfunction.

Although the troubleshooting procedure is based on monitoring flow, pressure and direction of flow, there are other system parameters that can be measured both to locate a faulty component and to determining the reasons for its malfunction:

• pressure at the inlet to the pump (vacuum) - for troubleshooting the suction lines;
• temperature - usually a higher temperature in one of the components of the system (compared to the temperature of the rest) is a sure sign that a leak is taking place;
• noise - With systematic and routine checks, noise is a good indicator of pump health.
• contamination level - in case of repeated occurrence of hydraulic system failures, the contamination of the working fluid should be checked to determine the causes of the malfunction.

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Special devices, tools and equipment for hydraulic system diagnostics

In a hydraulic system, pressure is usually measured with a pressure gauge or vacuum gauge, and flow is measured with a flow meter. In addition, the diagnostician may benefit from other devices and tools:

• pressure transducer and recorder - if the accuracy of pressure measurement must be higher than the accuracy provided by the pressure gauge, as well as if it is necessary to measure pressure during a transient process or under the action of reactive disturbances from an external load (the pressure transducer produces an alternating voltage depending on the applied pressure);
• graduated vessel and stopwatch - when measuring very small flows, for example, leaks, they can be used to obtain greater accuracy than when measuring with a flow meter;
• temperature sensor or a thermometer - to measure the temperature in the hydraulic tank, you can install a temperature sensor (often combined with a working fluid level indicator), and it is recommended to use a sensor that gives an alarm as soon as the temperature of the working fluid becomes too low or too high;
• thermocouple - to measure the local temperature in the system;
• noise meter - increased noise is also a clear sign of system malfunction, especially for the pump. A noise meter can always be used to compare the noise level of a "suspect" pump with the noise level of a new pump;
• particle counter - allows you to determine the level of contamination of the working fluid with a high degree of reliability.

Diagnostics of the hydraulic system in the event of a functional malfunction in the excavator

Step 1. Wrong work drive may have the following reasons:

• the speed of the actuator does not match the specified one;
• the supply of the working fluid of the actuator does not correspond to the specified one;
• lack of movement of the actuator;
• movement in the wrong direction or uncontrolled movement of the actuator;
• incorrect sequence of switching on the actuators;
• "creep" mode, very slow operation of the actuator.

Step 2. According to the hydraulic diagram, the brand of each component of the system and its function are determined

Step 3. Make lists of nodes that may be the cause of the malfunction of the machine... For example, insufficient speed of the actuator of the drive may be the result of insufficient fluid flow entering the hydraulic cylinder, or its pressure. Therefore, it is necessary to compile a list of all the nodes that affect these parameters.

Step 4. Based on a certain diagnostic experience, the priority order of checking the nodes is determined.

Step 5. Each node in the list is pre-checked in order. The check is carried out according to such parameters as correct installation, tuning, signal perception, etc., in order to detect abnormal signs (such as elevated temperature, noise, vibration, etc.)

Step 6. If, as a result of a preliminary check, a faulty unit is not found, then a more intensive check of each unit is carried out using additional tools, without removing the unit from the machine.

Step 7. Verification using additional devices should help you find a faulty unit, after which you can decide whether it should be repaired or replaced.

Step 8. Before restarting the machine, it is necessary to analyze the causes and consequences of the malfunction.... If the problem is caused by dirt or an increase in the temperature of the hydraulic fluid, it may recur. Accordingly, it is necessary to take further measures to eliminate the malfunction. If the pump breaks down, then its debris could enter the system. Before connecting a new pump, the hydraulic system should be thoroughly flushed.

* Think about what could have caused the damage, as well as the further consequences of this damage.

Excavators are designed to work with frozen or not soils, as well as with pre-crushed rocks. The operating temperature range of the equipment is -40 ... + 40 ° С. The excavator device includes several units that ensure the operation of the machine.

How aggregates are classified

Excavators equipped with a working body with one bucket are divided into categories:

1. By functional purpose. There are machines designed for construction work, special and career. The latter are equipped with a reinforced bucket designed for working with rocks.
2. According to the design of the chassis - wheeled on a special chassis, wheeled on an automobile chassis, tracked. The latter can be equipped with extended track belts.
3. By the type of drive of the working body - hydraulic, electric, combined.

How an excavator works

The general arrangement of an earth-moving excavator includes:

• undercarriage;
• engine;
• hydraulic system;
• transmission;
• a cabin with controls;
• platform with a rotating device;
• working boom.

An internal combustion engine with compression ignition is mounted on the turntable. The motor has a system liquid cooling... The cooling fans are driven automatically, but there is a forced switch button. To increase power and reduce fuel consumption, the installation of turbochargers is used. The engine drives the working mechanisms of the excavator through a hydraulic or electric transmission. Mechanical transmissions are used on outdated equipment.

The swivel part is mounted on the chassis through a shoulder strap that provides 360 ° rotation. The platform houses the operator's cab, hydraulic and electrical systems, boom with drive and control mechanisms. The excavator boom can be fitted with a variety of bucket designs or a trencher to reduce the time required to create trenches. It is possible to install hydraulic hammers or other equipment required for excavation work.

On excavators with a mechanical drive, winches are used that directly control the movement of the boom. On machines there are winches with 1 or 2 shafts. A 1-shaft unit is a unit in which the lifting and traction drums are mounted on a single shaft. If the drums of the winch are spaced along the shafts, then it is called 2-shaft. Similar mechanisms are installed on large excavators.

The winches are driven by shafts through a gearbox or by a chain from the main shaft of the transmission. Multi-disc friction clutches are used for switching on, band brakes for stopping. The rope is laid on the drum in one or more layers, depending on the length.

The design of a mini-excavator does not differ from the principles laid down in full-size equipment. The difference lies in the simplified design of the hydraulics and the use of a small diesel engine. The operator's workplace is located in a closed cabin equipped with ventilation and heating systems.

The loader excavator device is different from the above described mechanism. The work bucket is located on the articulated boom at the front of the standard wheeled tractor... The loading equipment has a hydraulic drive, which is controlled from the operator's cab.

480 RUB | UAH 150 | $ 7.5 ", MOUSEOFF, FGCOLOR," #FFFFCC ", BGCOLOR," # 393939 ");" onMouseOut \u003d "return nd ();"\u003e Dissertation - 480 rubles, delivery 10 minutes , around the clock, seven days a week

Melnikov Roman Vyacheslavovich. Improvement of methods for diagnosing hydraulic drives of road-building machines on the basis of studies of hydrodynamic processes in hydraulic systems: dissertation ... Candidate of technical sciences: 05.05.04 Norilsk, 2007 219 p. RSL OD, 61: 07-5 / 3223

Introduction

Chapter 1. Analysis of the existing maintenance system and the general state of the issue of the dynamics of the working fluid

1.1. The role and place of diagnostics in the system of maintenance of hydraulic drives SDM

1.2. General state of the issue of hydrodynamics of hydraulic drive SDM 17

1.3. Review of Research on Hydraulic Drive Dynamics

1.3.1. Theoretical research 24

1.3.2. Experimental studies 42

1.4. The use of electrohydraulic analogies in the study of wave processes in RZ in hydraulic systems SDM

1.5. Review of diagnostic methods for hydraulic drive SDM 52

1.6. Chapter Conclusions. Research goal and objectives 60

Chapter 2. Theoretical studies of hydrodynamic processes as applied to hydraulic systems SDM

2.1. Study of the propagation of the main harmonic along the hydraulic system of the SDM

2.1.1. Modeling the passage of the main harmonic through obstacles

2.1.2. General definition of the transfer function of a single-stroke double-acting hydraulic cylinder

2.1.3. Determination of pressure in the hydraulic line with oscillating excitation by solving the telegraph equation

2.1.4. Modeling wave propagation in hydraulic lines based on the method of electrohydraulic analogies

2.2. Assessment of the magnitude of the shock pressure in the hydraulic systems of construction machines using the example of the bulldozer DZ-171

2.3. Dynamics of the interaction of the pulsating RL flow and the pipeline walls

2.4. The relationship between oscillations of the walls of the hydraulic lines and the internal pressure of the working fluid

2.5. Chapter 103 Conclusions

Chapter 3. Experimental studies of hydrodynamic processes in hydraulic systems SDM

3.1. Justification of the experimental research methodology and the choice of variable parameters

3.1.1. General Provisions... The purpose and objectives of experimental research

3.1.2. Technique for processing experimental data and estimation of measurement errors

3.1.3. Determining the Regression Equation Type 106

3.1.4. Methodology and order of experimental research

3.2. Description of equipment and measuring instruments 106

3.2.1. Stand for research of wave processes in hydraulic systems

3.2.2. Vibration analyzer SD-12M 110

3.2.3. Vibration sensor AR-40 110

3.2.4. Digital tachometer / stroboscope "Aktakom" ATT-6002 111

3.2.5. Hydraulic press 111

3.3. Study of static deformation of high pressure hoses under load

3.3.1. Investigation of the radial deformation of RVD 113

3.3.2. Investigation of axial deformation of a high pressure hose with one free end

3.3.3. Determination of the form of the regression equation P \u003d 7 (Ds1) 121

3.4. On the question of the characteristics of the vibrations of the SDM in different areas of the spectrum

3.5. Study of the wave propagation speed and damping decrement of a single pulse in the MG-15-V liquid

3.6. Investigation of the nature of pressure pulsations in the hydraulic system of the EO-5126 excavator by vibrations of the walls of the hydraulic lines

3.7. Hydrodynamics of the working fluid in the hydraulic system of the DZ-171 bulldozer when lifting the blade

3.8. Study of the dependence of the amplitude of the main harmonic on the distance to the throttle slot

3.9. Conclusions on chapter 157

4.1. Selection of diagnostic parameter 159

4.3. Overflow criterion 165

4.4. Characteristics of analogues of the proposed method 169

4.5. Advantages and disadvantages of the proposed method 170

4.6. Specific Application Examples 171

4.7. Some technical aspects of the proposed diagnostic method

4.8. Calculation of the economic effect from the implementation of the proposed express method

4.9. Evaluation of the effectiveness of the implementation of the method of express diagnostics

4.11. Conclusions on chapter 182

Conclusions on work 183

Conclusion 184

Literature

Introduction to work

Relevance of the topic.The efficiency of maintenance of road construction machines (SDM) largely depends on the high-quality performance of technical diagnostics of the machine and its hydraulic drive, which is an integral part of most SDM. In recent years, in most sectors of the national economy, there is a transition to maintenance of road construction equipment according to the actual technical condition, allowing to exclude unnecessary repair operations Such a transition requires the development and implementation of new diagnostic methods for hydraulic drives SDM

Diagnostics of a hydraulic drive often requires assembly and disassembly work, which is associated with a significant amount of time. time, one of the sources of machine vibrations are hydrodynamic processes in hydraulic systems, and the vibration parameters can be used to judge the nature of the flowing hydrodynamic processes and the state of the hydraulic drive and its individual elements

By the beginning of the XXI century, the possibilities of vibration diagnostics of rotating equipment had grown so much that it formed the basis of measures for the transition to maintenance and repair of many types of equipment, for example, ventilation equipment, according to the actual state.However, for SDM hydraulic drives, the nomenclature of defects detected by vibration and the reliability of their identification is still insufficient to make such important decisions

In this regard, one of the most promising methods for diagnosing and hydraulic drives of SDM are methods of in-place vibration diagnostics based on the analysis of parameters of hydrodynamic processes

Thus, the improvement of methods for diagnosing hydraulic drives of road construction machines based on studies of hydrodynamic processes in hydraulic systems is actualscientific and technical problem

The purpose of the dissertation workconsists in the development of diagnostic methods for hydraulic drives SDM, based on the analysis of the parameters of hydrodynamic processes in hydraulic systems

To achieve this goal, it is necessary to solve the following tasks

Investigate the current state of the issue of hydrodynamics
hydraulic drive SDM and find out the need to take into account the hydrodynamic
processes for the development of new diagnostic methods
hydraulic drives SDM,

build and investigate mathematical models of hydrodynamic processes occurring in hydraulic systems of the SDM,

Experimentally investigate hydrodynamic processes,
flowing in hydraulic systems SDM,

Based on the results of the research conducted, develop
recommendations for improving diagnostic methods
hydraulic systems SDM,

Research object- hydrodynamic processes in hydraulic drive systems SDM

Research subject- regularities that establish links between the characteristics of hydrodynamic processes and methods for diagnosing hydraulic drives SDM

Research methods- analysis and generalization of existing experience, methods of mathematical statistics, applied statistics, mathematical analysis, method of electrohydraulic analogies, methods of the theory of equations of mathematical physics, experimental research on a specially created stand and on real cars

Scientific novelty of the results of the dissertation work:

A mathematical model of the passage of the first harmonic of pressure pulsations created by a volumetric pump (main harmonic) was compiled, and general solutions of the system of differential equations describing the propagation of the main harmonic along the hydraulic line were obtained,

Analytical dependencies for determining
internal fluid pressure in the RVD by deformation of it
multi-celled elastic shell,

The dependences of the deformation of the RVD on the internal
pressure,

Vibration spectra are experimentally obtained and investigated
elements of hydraulic lines in the HS of the EO-5126 excavator, D3-171 bulldozers,
self-propelled jib crane KATO-1200S in operating conditions,

a method for vibrodiagnostics of SDM hydraulic systems based on the analysis of the parameters of the fundamental harmonic of pressure pulsations generated by a positive displacement pump is proposed,

a criterion for the presence of a leakage in the hydraulic system of the SDM when using a new method of CIP technical diagnostics is proposed,

substantiated the possibility of using the parameters of hydraulic shocks arising as a result of a delay in the operation of safety valves for diagnostics of HS SDM

The practical significance of the results obtained.

a new method of vibration diagnostics for localizing faults in the elements of the hydraulic drive of the SDM is proposed,

a laboratory bench was created for the study of hydrodynamic processes in hydraulic systems,

The results of the work are used in the educational process in
lecture course, with coursework and diploma design, and
created laboratory facilities are used in carrying out
laboratory work

Privatecontribution applicant.The main results were obtained by the author personally, in particular, all analytical dependencies and methodological developments of experimental studies.When creating laboratory stands, the author proposed a general layout, calculated the main parameters and substantiated the characteristics of their main nodes and aggregates. practical implementation in operating conditions The author has personally developed programs and methods of experimental research, conducted research, processed and summarized their results, developed recommendations for the design of HS OGP taking into account wave processes

Approbation of work results.The results of the work were reported at the STC of the Norilsk Industrial Institute in 2004, 2005 and 2006, at the VIT All-Russian scientific and practical conference of students, postgraduates, doctoral students and young scientists "Science of the XXT century" MSTU in Maikop, at the scientific and practical conference "Mechanics - XXI century "BrSTU in Bratsk, at the 1st" All-Russian scientific and practical conference of students, graduate students and young scientists "in Omsk (SibADI), at the All-Russian scientific and practical conference" The role of mechanics in the creation of effective materials, structures and machines XXI

century "in Omsk (SibADI), as well as at scientific seminars of the Department of TMiO Research Institute in 2003, 2004, 2005 and 2006 Are brought to the defense -

scientific substantiation of a new method of express-diagnostics of hydraulic systems of SDM, based on the analysis of parameters of hydrodynamic processesat HS,

substantiation of the effectiveness of using the proposed method of CIP technical diagnostics,

Publications.Based on the results of the research, 12 printed works were published, including 2 articles in publications included in the list of the Higher Attestation Commission of the leading peer-reviewed journals and publications, an application was filed for a patent for an invention

Connection of the topic of work with scientific programs, plans and themes.

The topic is being developed within the framework of the proactive state budget topic "Improving the reliability of technological machines and equipment" in accordance with the plan of research work of the Norilsk Industrial Institute for 2004-2005, in which the author participated as a performer

Implementation of work.Operational tests of the express method for searching for leaks were carried out, the results of the work were accepted for implementation in the technological process at the enterprise MU "Avtokhozistvo", Norilsk, and are also used in the educational process at the State Educational Institution of Higher Professional Education "Norilsk Industrial Institute"

Work structure.The dissertation work consists of an introduction, four chapters fromconclusions, conclusions, a list of sources used, including 143 titles, and 12 annexes The work is presented on 219 pages, including 185 pages of the main text, contains 12 tables and 51 figures

The author considers it necessary to express gratitude to Melnikov VI, Candidate of Technical Sciences, Associate Professor of the Department of Technological Machines and Equipment (TMiO), GOUVPO Norilsk Industrial Institute (SRI), and Bashkirov BV, training master of the Department of TMiO SRI for help work

Main kept woman work

In the introductionsubstantiated the relevance of the dissertation topic, indicated the purpose of the work, formulated scientific novelty and practical value, provided a summary of the work and information about its approbation

In the first chapterthe modern system of maintenance of the SDM is considered, while it is indicated that an important place in the technological process of maintenance and repair is occupied by technical diagnostics, which are of two main types: general diagnostics (D-1) and in-depth diagnostics (D-2)

A comparative analysis of existing diagnostic methods was also carried out, while an acceptance was made on vibration methods One of the most frequently used methods in practice is the static-parameter method based on the analysis of parameters of a throttled flow of the working fluid This method is convenient in that it allows you to accurately identify the location of the fault, makes it possible when carrying out diagnostics, also adjust and run in the hydraulic system.At the same time, this method requires assembly and disassembly work, which leads to significant labor costs and leads to additional downtime Therefore, one of the directions for improving the MRO system is the development of CIP diagnostic methods, in particular, methods based on the analysis of the parameters of hydrodynamic processes in working fluids

However, at present, the defects detected by vibration diagnostics systems do not have quantitative characteristics similar to those of the structural parameters of the object.In particular, during vibration diagnostics, for example, the geometric dimensions of elements, the size of gaps, etc. are not determined. Quantitative estimates of the detected defects can considered a probabilistic assessment of the risk of an accident during the further operation of the equipment Therefore, the name of the detected defects often does not correspond to the names of those deviations of the element state from normal, which are monitored during the defect detection of equipment units. determining the effectiveness of vibration diagnostics systems

One of the most promising methods for modeling processes in hydraulic systems is the method of electrohydraulic analogies, in which each element of the hydraulic system is associated with a certain element of the electrical equivalent circuit

The general state of the issue of the hydrodynamics of the working fluid in volumetric hydraulic systems is investigated, and a review of works on this issue is carried out. It is determined that hydrodynamic processes have

significant impact on the performance of machines It is indicated that in a practical aspect, namely in the aspect of improving performance characteristics energy-intensive harmonics of large amplitude are important, therefore, when conducting research, it is advisable to focus attention, first of all, on them, that is, on harmonics of low frequency

Based on the research results, the goal and objectives of the research were formulated

In the second chapterthe results of theoretical studies of hydrodynamic processes in the RL are presented, the issue of the passage of waves through an obstacle is investigated, and on this basis the transfer functions for the passage of waves through some elements of hydraulic systems are obtained.In particular, the transfer function for some obstacle in the form of a gap in a pipe of constant cross section has the following form

4 - ( J>

w = ^-= -.

where and]- the amplitude of the incident wave, and 3 is the amplitude of the wave passing through the slit, to- the ratio of the cross-section of the pipe to the area of \u200b\u200bthe hole

For a double-acting single-stem hydraulic cylinder in the presence of overflow, the transfer function will have the form

1**" (2)

W =-

{1 +1 ") to " +1?

where t - the ratio of the area of \u200b\u200bthe piston to the area of \u200b\u200bthe rod, to -ratio of piston area to overflow area, U -the ratio of the effective cross-sectional area of \u200b\u200bthe hydraulic line to the piston area In this case, the internal diameters of the drain and pressure hydraulic lines are assumed to be equal to each other

Also in the second chapter, based on the method
electrohydraulic analogies modeling

propagation of a harmonic wave along a hydraulic line with distributed parameters Equations are known that describe rc and voltage in the line as a function of coordinates x nt

I th _ di

where R 0 is the longitudinal active resistance of a unit of line length, L 0 is the inductance of a unit of line length, Co is the capacitance of a unit of line length and G 0 is the transverse conductivity of a unit of line length. The equivalent circuit of an electric line is shown in Fig. 1

-1-G-E-

The well-known solution of system (3), expressed in terms of voltage and current at the beginning of the line, has the form

U= U, ch (yx) -/, Z Bsh (yx)

l \u003d I, c) i [) x) - ^ -, h () x)

V№ + y) labout)

constant spread,

\\ n + / wr ~ ~~wave impedance

Neglecting leaks, that is, assuming the hydraulic equivalent G 0 equal to іgul, we obtain equations for determining the harmonic function of pressure and flow rate at any point of the line, expressed in terms of pressure and flow rate at the beginning of the line

I Q \u003d P, ch (y lX) - Q- Sh (y rx)

Q- volumetric flow, 5 - pipe cross-section, R - pressure, p \u003d p e>-",

Q \u003d Q e" w+*>) , from- wave propagation speed, p 0 - density, and -

friction parameter, ω is the circular frequency of the wave After substitution of hydraulic analogs of electrical quantities into system (4), the solution of system (5) was obtained

I\u003e \u003d l \\ cf \\ x- ^ + ^- (-sinH + jcosH

- v \\ c \\ p,

V../ ,. 4l ", __ J / rt ..._," "J _".!,. 4 *. " (_ 5sh ^) + wso f)) | (8)

Є \u003d 0сй | * -4І + - (-sm (9) + v cos (i9))

Ї 1 + 4Ph (cos (0) - 7 smH) V o) pi

Taking into account the reflected wave, the pressure in the hydraulic line as a function of the coordinate and time takes the form

where R () H - the wave generated by the positive displacement pump, defined by expression (8), r -reflected wave

P ^ \u003d U, ") cP (g (l-x)) K 0 -Q (I, t) 7„Sh ( K (l-x)) K 0 (10)

where the reflection coefficient is determined by the expression r _ Zii-Zlb - Z „- hydraulic load resistance ~7 +7

The resulting model is valid not only for hydraulic lines with absolutely rigid walls of the hydraulic line, but also for high pressure hoses.In the latter case, the wave propagation speed should be calculated using the well-known formula

where r -radius of the hydraulic line, d -wall thickness, K -reduced bulk modulus of elasticity

The assessment of the maximum value of pressure overshoots in the event of hydraulic shocks in the hydraulic system of the DZ-171 bulldozer (basic machine T-170), arising from the stop of the hydraulic cylinders for lifting the blade, the resulting value was Ar, k 24.6 MI FaIn case of water hammer occurrence, in case of delay

actuation of safety valves for a time of 0.04 s, theoretically the maximum value of pressure overshoots in the hydraulic system of this machine is 83.3 MPa

Due to the fact that the measurements were supposed to be carried out on real machines by the CIP method, the question of the relationship between the amplitude of vibration displacements and vibration accelerations of the outer walls of pressure hydraulic lines and the amplitude of pressure pulsations in the hydraulic lines was considered.The resulting dependence for a rigid pipe has the form

dgf. ^ (D (p\u003e : -gCr. "і ^ + ^ -І

where x, -amplitude of vibration displacement of the pipe wall by i-Piiharmonics, E -young's modulus for the wall material, d -inner diameter of the hydraulic line, D- outer diameter of the hydraulic line, r" -fluid density, r st - density of the material of the walls of the hydraulic line, w, - frequency z harmonics.

V Vh / d H lr

H ^ 4 h

Figure 2 - Calculation scheme for determining the analytical dependence of the deformation of the metal braid of the RVD about g of the amplitude of the pulsations of the internal pressure

Similar dependency of multilayer metal braided flexible hose

reinforced (13)

where t - number of RVD braids, „ - number of strands in one section of one

braids, to and - depreciation coefficient of the outer lining, S! - area

the cross-section of one braid wire, and -the angle of inclination of the tangent to the plane perpendicular to the axis of the cylinder (Figure 2), x, -the value of the vibration displacement amplitude of the i-th harmonic, d -diameter of one braid wire, Do -reduced diameter of all RVD braids, S l -

value of the amplitude of the vibration velocity of the 7th harmonic at a frequency (o i, (r -angle of rotation of the radial ray connecting the point on the helical

lines and under 90 axis of the cylinder (sleeves), Have f- the volume of liquid contained inside the RVD in the contour of the wire area, V cm - volume of the part of the wall corresponding to the contour of the thread y \u003d d 8 U d D e 5 - wall thickness of the RVD,

th? Wed - the average diameter of the RVD, r f- fluid density

After solving equation 13 for the most common case, that is, with a \u003d 3516 ", and neglecting the inertial forces of the RVD walls in comparison with the elastic forces of the braids, a simplified dependence was obtained

d R = 1 , 62 Yu*^± X , ( 14 )

Doі

The third chapter presents the results of experimental studies

To substantiate the possibility of measuring the parameters of hydrodynamic processes in the RZ with the help of overhead sensors, a study was made of the dependence of the static deformation of the RVD on the internal pressure. RVD brand - B-29-40-25-4-U TU-38-005-111-1995, calculated for the nominal pressure Р nom \u003d 40 MPa RVD characteristic length - 1.6 m, inner diameter - 25 mm, outer diameter - 40 mm, the number of braids - 4, the diameter of the braid wire - 0.5 mm The radial and axial deformation of the high pressure hose was investigated when the pressure changed from 0 to 12 MPa

For RVD with both fixed ends, the dependence
radial deformation from pressure is shown in Fig. 3
that the RVD behaves differently with increasing pressure (the upper curve
in Fig. 3 a) and b)), and with a decrease in pressure (lower curve in Fig. 3 a) and
b)) Thus, the existence of the known phenomenon was confirmed
hysteresis during deformation of the RVD Work expended on deformation
for one cycle per one meter of the length of this RVD, turned out to be the same for
in both cases - 6.13 J / m It was also established that at large
pressures (\u003e 0.2P, IOVI), radial deformation remains practically
unchanged Such differentiation can probably be explained by the fact that
that in the section from 0 to 8 MPa the increase in diameter is due to
mainly by sampling the backlash between the layers of the metal braid, and
also by deformation of the non-metallic base of the hose.
circumstance means that at high pressures damping
the properties of the hydraulic line itself are insignificant, the parameters

hydrodynamic processes can be investigated by the parameters of the vibrations of the hydraulic line.It was found by the method of finite differences that the optimal regression equation describing the dependence P \u003d J.

The difficulty of toolless identification of a faulty assembly leads to increased maintenance and repair costs. When determining the reasons for the failure of any element of the system, it is necessary to carry out assembly and disassembly work.

Taking into account the latter circumstance, methods of CIP technical diagnostics are highly effective. In connection with the rapid development of computer technology in recent years, the reduction in the cost of hardware and software for digital measuring instruments, including vibration analyzers, a promising direction is the development of methods for CIP vibration diagnostics of hydraulic drives SDM, based, in particular, on the analysis of hydrodynamic processes in horizontal wells.