RU2071115C1 - Device for determining optimal maintenance intervals - Google Patents

Abstract

FIELD: computer engineering; inspection devices. SUBSTANCE: device has time sensor 1, integrator 3, multiplying units 4,5,7,11,18,20, adders 8,9, nonlinearity unit 17, subtracters 2,19, 21, dividing units 6,10, comparator 13, delay element 12, switches 14,15,16,22. EFFECT: enlarged functional capabilities due to determining minimal average specific unproductive life expenditure. 3 dwg

Description

 The invention relates to the field of computer technology, in particular to control devices, and can be used in scientific research and technology, where it is required to find the optimal period of control and maintenance of the product according to the criterion of the minimum specific unproductive resource consumption per unit time of useful functioning of the product, conditions of changing the reliability characteristics of the product during its operation.

 The aim of the invention is to expand the scope of the device by determining the minimum criterion for the average value of the specific unproductive resource consumption per unit of useful life, with increasing failure rate for products whose failure time can be described by the Rayleigh distribution margin.

 The product during operation may be in various states: operational state, in a state of latent failure, control and restoration of operability. Emerging failures are detected only during scheduled monitoring sessions, which are conducted with a period of τ. If a failure is detected as a result of the control, then measures are taken to restore the product to working capacity, otherwise, planned preventive maintenance is carried out. As a result of planned prevention and restoration of performance, the reliability characteristics of the product are restored.

All products have limited resources (vital resources) that they spend in the process of functioning. At the same time, the rate of expenditure of resources may be different depending on the technical condition of the product. Let / R _x / be the set of resources corresponding to the set of considered product states, and
R _{to the} resource consumed as a result of one session of monitoring the health of the product;
R _{in the} resource spent on restoring the product in the event of a failure;
R _p resource spent on routine prevention.

где C_ф средний расход ресурса в единицу времени в работоспособном состоянии;
С_о средний расход ресурса в единицу времени в состоянии скрытого отказа;
N число циклов обслуживания, которое может быть выполнено при полном израсходовании ресурса;
1-P(τ) вероятность отказа изделия на периоде обслуживания.Then, according to the total limited resource of the product R, one can write a balance relation of the following form:

where C _{f the} average consumption of a resource per unit of time in operable condition;
With _{about the} average resource consumption per unit time in a state of latent failure;
N is the number of service cycles that can be performed when the resource is completely used up;
1-P (τ) probability of product failure during the service period.

Часть ресурса, которую изделие расходует, находясь в состоянии скрытого отказа, во время контроля, плановой профилактики и восстановления по работоспособности называется непроизводительно расходуемым ресурсом.

The part of the resource that the product spends while in a state of latent failure during control, planned preventive maintenance and restoration by working capacity is called an unproductive resource.

Важнейшей характеристикой изделия и системы его эксплуатации является средний удельный непроизводительный расход ресурса, приходящийся на единицу времени безотказной работы изделия. Значение этого ресурса, используя (2), можно определить по формуле:

Так как момент наступления отказов случаен, то среднее время безотказной работы изделия на периоде обслуживания можно определить по формуле

где Р(t) вероятность безотказной работы изделия.The value of this resource spent during one product maintenance cycle will be:

The most important characteristic of a product and its operation system is the average specific unproductive consumption of a resource per unit of product uptime. The value of this resource using (2) can be determined by the formula:

Since the moment of occurrence of failures is random, the average product uptime during the service period can be determined by the formula

where P (t) is the probability of failure-free operation of the product.

Как известно, для обслуживаемых изделий разрабатываются стратегии их обслуживания. Важным параметром такой стратегии является период обслуживания, который может быть постоянным ("жесткие" по периодичности стратегии) или переменным ("гибкие" стратегии).The average time spent by the product in a state of latent failure will be

As you know, service strategies are developed for serviced products. An important parameter of such a strategy is the service period, which can be constant (“rigid” strategies for periodicity) or variable (“flexible” strategies).

принимает минимальное значение. Поэтому задача определения оптимального периода обслуживания изделия может быть записана в следующем виде:

Для многих изделий, работающих длительное время, интенсивность отказов с течением времени возрастает и вероятность безотказной работы Р(t) таких изделий можно описать законом распределения Рэлея,

где К параметр закона распределения Рэлея. Тогда:

При этом среднее значение непроизводительно расходуемого ресурса Rф за время эксплуатации изделия на заданном ограниченном ресурсе R будет следующим:
R $\genfrac{}{}{0ex}{}{\text{*}}{\text{ср}}$ =R_ср(τ^*)=N(τ^*)•R_н(τ⁸)
или

Важно также знать среднее значение числа резервных элементов

необходимых для эксплуатации изделия на заданном ограниченном ресурсе R, которое определяется следующим образом:

Cущность изобретения поясняется чертежом. На чертеже приведена блок-схема устройства.If maintenance is carried out rarely, with a long period, then the product for a long time may be in a state of latent failure, while spending a resource unproductive. If maintenance is carried out frequently, with a short period, then the residence time of the product in a state of latent failure decreases, but the proportion of time spent on monitoring and scheduled maintenance of the product increases. Moreover, the product is not able to function as intended, and the resource consumed by it is consumed unproductively. In this and another case, the average specific non-productive consumption of the resource is overestimated. There is some optimal τ ^* product service period at which

takes a minimum value. Therefore, the task of determining the optimal service period for the product can be written in the following form:

For many products that work for a long time, the failure rate increases over time and the probability of failure-free operation P (t) of such products can be described by the Rayleigh distribution law,

where K is the parameter of the Rayleigh distribution law. Then:

In this case, the average value of unproductive expendable resource Rf during the operation of the product at a given limited resource R will be as follows:
R $\genfrac{}{}{0ex}{}{\text{*}}{\text{wed}}$ = R _cf (τ ^* ) = N (τ ^* ) • R _n (τ ⁸ )
or

It is also important to know the average number of redundant items.

necessary for the operation of the product on a given limited resource R, which is determined as follows:

The invention is illustrated in the drawing. The drawing shows a block diagram of a device.

 The device comprises a time sensor 1, a first subtractor 2, an integrator 3, a first 4 and a second 5 multiplication blocks, a first 6 division block, a third 7 multiplication block, a first 8 and a second 9 adders, a second division block 10, a fourth multiplication block 11, element 12 delays, comparator 13, first 14, second 15 and third 16 keys, non-linearity block 17, fifth multiplication block 18, second subtractor 19, sixth multiplication block 20, third subtractor 21 and fourth key 22. The time sensor 1 is a ramp generator .

 The device operates as follows.

c выхода первого вычитателя 2 поступает на вход блока 4, с выхода которого значение C_оt_о поступает на вход сумматора 8. Значение R_нP(t) c выхода блока 5 поступает на вход сумматора 8. Значение R_вP(t) c выхода блока 18 поступает на вход вычитателя 2, с выхода которого значение R_в[1-P(t)] поступает на четвертый вход первого сумматора 8. Значение

с выхода первого сумматора 8 поступает на вход второго сумматора 9, на вход блока умножения 11 и на вход блока деления 6. Значение

c выхода блока умножения 7 поступает на вход второго сумматора 9, с выхода которого значение

поступает на вход блока деления 10. Значение

с выхода блока деления 10 поступает на входы блока перемножения 20 и вычитателя 21 и на первый вход блока умножения 11. Значение R_cр(t) N(t)•R_н(t) c выхода блока умножения 11 поступает на информационный вход ключа 16. Значение N(t)•P(t) с выхода блока умножения 20 поступает на вход вычитателя 21, с выхода которого значение

поступает на вход ключа 22. Значение С_уд(t) R_н(t)/t_ф с выхода блока 6 поступает на один вход компаратора 13 и через элемент задержки 12 поступает на другой вход компаратора 13 и на вход второго ключа 15. Элемент 12 имеет время задержки Δt (величина Δt влияет на точность определения оптимального периода контроля работоспособности изделия). В компараторе 13 сравниваются между собой два значения С_уд(t) и C_уд(t-Δt) . Как только в момент времени t^*, С_уд(t^*) cтанет больше либо равно C_уд(t^*-Δt) на выходе компаратора 13 появится единичный управляющий сигнал, который поступает на входы первого 14, второго 15, третьего 16 и четвертого 22 ключей. В результате на первом выходе устройства будет значение оптимального периода τ^*=t^* обслуживания изделия, обеспечивающее минимум среднего значения удельного непроизводительного расхода ресурса C $\genfrac{}{}{0ex}{}{\text{*}}{\text{уд}}$ во время эксплуатации. На втором выходе устройства будет значение C $\genfrac{}{}{0ex}{}{\text{*}}{\text{уд}}$ . На третьем выходе устройства будет среднее значение непроизводительного расхода ресурса R $\genfrac{}{}{0ex}{}{\text{*}}{\text{ср}}$ за время эксплуатации изделия на заданном ограниченном ресурсе R и обслуживании изделия оптимальным периодом R, среднее значение числа резервных элементов

необходимых для нормального функционирования изделия при названных выше условиях, будет на четвертом выходе устройства. На этом работа устройства заканчивается.When the device is turned on, sensor 1 and key 17 are simultaneously launched into operation. From the first input of the device, the value of parameter С _{о is} received at the input of the multiplication block 4. From the fourth input of the device to the input of the multiplication block 7 receives the value of the parameter With _f . From the input of the device to the input of the adder 8 receives the value of the parameter R _to . From the second input of the device to the input of the multiplication block 5 receives the value of the parameter R _p . From the seventh input of the device, the value of parameter k is supplied to the first input of the non-linearity block 17. From the sixth input of the device, the value of parameter R _{c is} received at the inputs of the multiplication block 18 and the second subtractor 19. From the fifth input of the device, the value R is input to the input of the second division unit 10. The value t from the output of timer 1 is fed to the input of the subtractor 19, to the information input of the first key 14, and to the second input of the block 17. Signal value P (t) = exp (-t ² / 2k) from the output of block 17 goes to the first input of the multiplication block 20, to the second inputs of the multiplication block 5 and the multiplication block 18, and through the integrator 3 it goes to the first input of the first subtractor 2, to the input of block 7, and to the input of the first division block 6. Signal Value

c, the output of the first subtractor 2 goes to the input of block 4, the output of which the value C _о t _о goes to the input of the adder 8. The value of R _n P (t) from the output of block 5 goes to the input of the adder 8. The value of R _in P (t) c the output of block 18 goes to the input of the subtractor 2, from the output of which the value of R _in [1-P (t)] goes to the fourth input of the first adder 8. The value

from the output of the first adder 8 goes to the input of the second adder 9, to the input of the multiplication block 11 and to the input of the division unit 6. Value

c the output of the multiplication block 7 is fed to the input of the second adder 9, from the output of which the value

goes to the input of the division unit 10. Value

from the output of the division unit 10 is supplied to the inputs of the multiplication unit 20 and the subtractor 21 and to the first input of the multiplication unit 11. The value of R _cp (t) N (t) • R _n (t) from the output of the multiplication unit 11 goes to the information input of the key 16. The value of N (t) • P (t) from the output of the multiplication unit 20 is fed to the input of the subtractor 21, from the output of which the value

enters the input of the key 22. The value C _beats (t) R _n (t) / t _f from the output of the block 6 is supplied to one input of the comparator 13 and through the delay element 12 is fed to the other input of the comparator 13 and to the input of the second key 15. Element 12 has a delay time Δt (the value of Δt affects the accuracy of determining the optimal period for monitoring the health of the product). In the comparator 13, two values of C _beats (t) and C _beats (t-Δt) are compared with each other. As soon as at time t ^* , C _beats (t ^* ) become greater than or equal to C _beats (t ^* -Δt), a single control signal appears at the output of comparator 13, which is fed to the inputs of the first 14, second 15, third 16 and fourth 22 keys. As a result, at the first output of the device there will be a value of the optimal period τ ^* = t ^{* of} product service, providing a minimum of the average value of the specific unproductive consumption of the resource C $\genfrac{}{}{0ex}{}{\text{*}}{\text{beats}}$ during operation. The second output of the device will be the value C $\genfrac{}{}{0ex}{}{\text{*}}{\text{beats}}$ . The third output of the device will be the average value of unproductive resource consumption R $\genfrac{}{}{0ex}{}{\text{*}}{\text{wed}}$ during the operation of the product on a given limited resource R and servicing the product with an optimal period R, the average value of the number of reserve elements

necessary for the normal functioning of the product under the above conditions, will be on the fourth output of the device. On this, the operation of the device ends.

Claims (1)

 A device for determining the optimal period of service of the product, containing a time sensor, the output of which is connected to the first input of the nonlinearity block, the output of which is connected to the input of the integrator, the output of which is connected to the first input of the first division block, the first adder, the output of which is connected to the second input of the first division block , the output of which is directly and through a delay element connected to the inputs of the comparator, the first inputs of the first, second and third keys are interconnected, the outputs of the first, second third and the fourth keys are the outputs of the device, the first inputs of the first and second multiplication blocks are the first and second inputs of the device, the output of the first multiplication block is connected to the first input of the first adder, the second input of which is the third input of the device, and the third input of the first adder is connected to the output of the second block multiplication, the second input of which is connected to the output of the nonlinearity block, the first inputs of the third multiplication block and the second division block are the fourth and fifth inputs of the device, respectively the grated and fifth multiplication blocks, the first input of the last of which is the sixth input of the device, the output of the fifth multiplication block is connected to the first input of the first subtractor, the sixth multiplication block and the second adder, characterized in that, in order to expand the scope of the device by determining the minimum criterion the average value of the specific unproductive resource consumption, the second and third subtracters are introduced into it, the output of the time sensor is connected to the second input of the first key and the first input of the second subtractor, the second input which is connected to the second input of the third multiplication unit and connected to the integrator output, the output of the second subtractor is connected to the second input of the first multiplication unit, the output of the first subtractor is connected to the fourth input of the first adder, the output of which is connected to the first input of the fourth multiplication unit and the second adder, the second the input of which is connected to the output of the third block of multiplication, and the output of the adder with the second input of the second block of division, the output of which is connected to the second input of the fourth block of multiplication, to the first input the third subtractor and to the first input of the sixth multiplication unit, the output of which is connected to the second input of the third subtractor, the output of which is connected to the first input of the fourth key, the output of the comparator is connected to the second input of the fourth key and to the first input of the third key, the second input of which is connected to the fourth output of the multiplication unit, the output of the delay element is connected to the second input of the second key, the second input of the nonlinearity block is the seventh input of the device, the output of the nonlinearity block is connected to the second input of the sixth block multiplications, the second input of the first subtractor and the first input of the fifth block of multiplication are combined.

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