SU1679512A1 - Device for estimating systemъs optimal maintenance period - Google Patents

Abstract

The invention relates to monitoring devices and can be used in scientific research and engineering, where it is required to find optimal monitoring and maintenance periods that deliver maximum system availability, useful system operation time for a given limited resource, and system availability. The goal is to increase the information content of the device. The device contains analyzer 1, delay element 2, comparison element 3, time sensor 4, multiplication unit 5, first 6, second 7 and third 8 keys, m calculators of the availability of the 9i9m subsystems, each of which contains adder 10, multiplication unit 11, functional a converter 12, a division block 13 and an integrator 14. 1 h. item f-ly, 1 ill.

Description

Yo

The invention relates to monitoring devices and can be used in scientific research and engineering, where it is required to find optimal monitoring and maintenance periods (TO), delivering maximum system availability, useful system operation time at a given limited resource, and system availability. .

The aim of the invention is to increase the information content of the device by determining the useful life of the system on a given limited resource, the system availability factor, and also performing an operation of comparing the values of subsystem availability factors simultaneously (in parallel).

Many automated controls are used in standby mode. The transfer of these funds to the target operation mode is generally performed at a random point in time, the presence of a failure at the moment of switching on leads to failure of the target task. In order to maintain such automated control means in good condition, they are periodically and periodically subjected to technical maintenance, consisting in condition monitoring and repair when a failure is detected. An important characteristic of the system operating in standby mode is the availability factor, which is defined as follows:

About VI Yu

cl

Yu

g - Tf (g-f.

where Tf is the average useful life of the system, i.e., the time during which it performs the target task or is ready to perform the target task;

T is a predetermined operating time (limited resource) during which the system is useful or in a state of failure or maintenance.

If you do not carry out maintenance of the system, the time during which it can be useful to function corresponds to the useful life of the system until the first failure in any of its subsystems. Increasing the number of monitoring sessions of a complex system increases its useful life by eliminating failures, but it also increases the maintenance resource consumption, which reduces the useful operation life. Therefore, there is some appropriate period between the control and maintenance sessions, which delivers the longest useful life of the complex system, and hence the highest value of Kg.

Since the real system in the general case consists of a set of differently reliable subsystems, for each subsystem there will be its own optimal period of control and maintenance, delivering a maximum of Cg of this subsystem. At the same time, in the practice of operating many complex systems, it is advisable to carry out monitoring and maintenance of the system simultaneously. The problem arises - to find the rational period of control and maintenance that would provide the largest Kg of the entire system.

Suppose that there are m subsystems in the complex system, 0 Tjn). For each monitoring and maintenance session, jTOflcncTeM, on average, time is spent} /), and for the subsystem to recover when a failure occurs in it, on average, the Gj time.

Monitoring and maintenance of all subsystems are carried out with the same frequency over the time of the year. The failures occurring during this period are detected only as a result of the monitoring. It is considered that if any of the subsystems fail, the complex system cannot fulfill the intended purpose. If the operating times of the subsystems Tj are also known, moreover, Tt T2 ... T and the probability of non-failure operation Pj (t) of each subsystem (j 1, m),

then the balance equation on resource T for the jth subsystem can be written as

0

five

0

five

five

 one

0

NJ | Гф + roj -f К + Ц 1 - Pj (r) j.

where NJ is the number of control and maintenance sessions of the Jth subsystem on resource T; .

TF - the average time of the useful functioning of the j-th subsystem on the period t

 Pj (t) dt;

TOJ is the average time the jth subsystem is in a failure state on period g,

Go - T - GF.

The average useful time of the Jth subsystem over time T will be Tf | NJ gf |. Then the availability of any of the subsystems of the monitored system is determined as follows:

K,

g T Toj + foj + u + H -P (t) J

The task of finding a common for all subsystems monitoring and maintenance period, delivering the highest value of the availability ratio of a complex system, is

to find a period r such that

KG (Y)

rxm. (r) 3

At the same time, if Tc is the specified time of active existence of the system, then the average useful life of the system, if serviced by a period g will be

Tf TS3M g)

and the system availability will be

Kg Kg (T). Dunn Mathematical Model

can be implemented in hardware.

The drawing shows a block diagram of the device.

The device contains an analyzer (selection of the minimum of m variables) 1, delay element 2, comparison element 3, time sensor 4, multiplication unit 5, first 6, second 7 and third 8 keys, m calculator of availability factors of subsystems 9-1, ... , 9-pn each

contains an adder 10, a multiplication unit 11, a functional converter 12, a division unit 13 and an integrator 14.

The device works as follows.

Time sensor 4 with step Ar sets, in order of increasing, the sequence of possible values of t for the period of control and maintenance of the system. P G | - 1 + Ar,

l 1.2,3, ... r0 0

The signal corresponding to m from the first output of the time sensor A is fed to the fourth inputs of the computing factors of the subsystem availability factors. In each such calculator, the availability factor Krij is calculated, corresponding to the Jth subsystem at each successive value m. The process of calculating the subsystem availability factor is considered using the j-ro calculator as an example. The signal n from the fourth input of the availability factor calculator of the jth subsystem is fed to the second input of the adder 10 and to the input of the functional converter 12. Functional probability probability function of the jth subsystem Pij (t) at period 0, m and s is formed in functional converter 12 the first output is fed to the input of the integrator 14. From the second output of the functional converter 12 to the second input of the multiplication unit 11, the probability of failure of the j-th subsystem at the instant of time T | Pj (ti). From the output of the integrator 14 to the first input of the division block 13 enters the value of the average useful operation time of the j-th subsystem on the period

Ts Fi Dre 0) dt At the first input of the multiplication unit 11 and at the third input of the adder 10, the value of the parameter 6} comes from the second input of the calculator of the availability factor, and from the first input of the calculator to the first input of the adder 10 - the pair value - meter y.

The result of multiplying O) Pj (ri) from the output of multiplication unit 11 is fed to the fourth input of the adder 10. The result of the summation

TI + XJ (ri) ri + Xj + 6} i -PJ (TJ) from the output of the adder 10 is fed to the second input of the division unit 13, in which the calculation of the availability factor of the J-th subsystem takes place

Krij

UFC

h + I + fP-RTta

The values of the availability factors of the subsystems from the outputs of the division block 13 of each calculator of the availability of the subsystem are fed to the corresponding inputs of the analyzer 1 for the selection of the minimum variable. At the output of the selection scheme, the minimum of m variables will be the value Kri rnin Krij, which goes to the first input of the element of comparison 3 and through

0 5

five

0

0

five

0

five

delay element 2 - to the second input of comparison element 3. At the output of delay element 2 there will be a signal KG | -1. delayed for one cycle of the device. After the time t has elapsed after the time sensor 4 issues an amplitude t from the control output of time sensor 4, the control input of the reference element 3 receives a control impulse signal. This signal is used to compare the signals at the two inputs of the element of comparison 3, i.e., the comparison is made at the moment of the end of the calculation of the readiness value of each subsystem. If CG | QC | -1, then from the first output of the comparison element 3 to the control input of the time sensor 4. To the control input of the delay element 2 and through the third input of each calculator of the subsystem availability subsystem to the control input of the integrator 14 receives a control signal. On the front of the control signal, the integrator 14 is reset to its original zero state, and in Delay 2, the input signal is written to the output. By decreasing the control signal from the first output of the element of comparison 3, time sensor 4 forms the next value of the monitoring period and T0 + 1 and the whole calculation cycle is repeated. If it turns out that Kri Kri-i, then from the second output of the comparison element 3 to the control input of the first 6, second 7 and third 8 keys receives a control signal. From the second output of the time sensor 4 to the information input of the third key 8, and from it the value of the optimal control period and

THAT T - H From the output of the delay element to the first input of the multiplication unit 5 and to the information input of the second key, the value of the Kr Kri-i system availability factor is supplied if it is serviced by the optimal period of control and maintenance

ji.

t. This value from the output of the second key 7 is fed to the second output of the device. The second input of the multiplier 5 from the input of the device receives the value of the specified time of active existence of the system Tc3. The result of multiplication, corresponding to the average useful operation time of the system, from the output of Tf Tc3 Kg of the multiplication unit 5 through the first key b is fed to the first output of the device. As a result, at the first output of the device, there will be a value of the average useful life of the system Tf, if it is serviced by the optimal period of control and TO t.

Claims (2)

Claim 1. A device for determining the optimal maintenance period of a system, comprising a time sensor, m calculators of the availability of subsystems, an analyzer, a delay element, a comparison element and the first key, the output of each of the m calculators of availability of the subsystems on the corresponding analyzer - connected to the first inputs of the comparison element and the delay element, the output of which is connected to the second input of the comparison element, the first output of which is connected to the input of the time sensor, the first output of which is connected to the first inputs of each calculator of the availability of subsystems, the second and third inputs of which are respectively the first and second inputs of the device, the second output of the time sensor connected to the information input of the first key, the output of which is the first output of the device, the second output of the comparison element is connected to the control input of the first key, characterized in that, in order to increase the information content, the second and third keys are entered into it and the block is multiplied and, the first input of which is the third input of the device, the first output of the comparison element is connected to the fourth inputs of all calculators of the subsystem availability factor and the second input of the delay element whose output is connected to the second input of the multiplication unit and to the information The second input of the second key, the output of which is the second output of the device, the third output of the time sensor is connected to the third input of the comparison element, the output of which is connected to the control inputs of the second and third keys, the second input of the last of which is connected to the output of the multiplication unit It is the third output of the device. 2. The device of claim 1, wherein the subsystem availability calculator comprises a multiplication unit, a functional converter, an integrator, a division unit, and an adder, the output of which is connected to the first input of the division unit, the output of which is the subsystem availability calculator output , the first output of the function converter is connected to the first input of the multiplication unit, the output of which is connected to the first input of the adder, the second output of the function converter is connected to the first input of the inte the grader whose output is connected to the second input of the division unit, the input of the functional converter is combined with the second input of the adder and is the first input of the subsystem availability calculator, the third input of the adder is the second input of the subsystem calculator, the second input of the multiplication unit is combined with the fourth input of the adder and is the third input of the subsystem availability calculator.