CN107169251B - Maintainability assessment method for wall-mounted air-conditioning system - Google Patents
Maintainability assessment method for wall-mounted air-conditioning system Download PDFInfo
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Abstract
The invention discloses a maintainability assessment method for a wall-mounted air-conditioning system, which comprises the steps of establishing a maintenance physical model of the system by analyzing the working principle of the air-conditioning system; analyzing the influence mode of the switch unit on the air conditioning system, and determining all possible states of the air conditioning system; determining the transition probability of the air conditioning system from one state to any other state under different influence modes of the switch unit; establishing a maintainability mathematical model of the air-conditioning system; and establishing an evaluation program. The invention establishes the functional relationship between the parts or components and units of the wall-mounted air-conditioning system and the system maintainability index, so that the maintainability prediction and distribution can be possible to be developed in the design and development process of the air-conditioning system, and the invention can also be used for predicting the maintainability of the air-conditioning system after installation and use, and provides a decision basis for making a scientific after-sale maintenance strategy.
Description
Technical Field
The invention relates to an air-conditioning system evaluation technology, which is suitable for analyzing and evaluating the maintainability level of a wall-mounted air conditioner in the design and use processes of the wall-mounted air conditioner, in particular to a method for evaluating the maintainability of the wall-mounted air conditioner.
Background
The maintainability model of the whole air conditioner system can be applied to a plurality of links such as demonstration, design, manufacture and use of air conditioner products, and the wall-mounted air conditioner is the most widely applied air conditioner product.
The maintainability index is a core index reflecting the quality of the air conditioner, and objectively and accurately evaluating the maintainability level of the air conditioner becomes a basic technical work of an enterprise, and is also widely concerned by consumers. Currently, there are two main ways for evaluating maintainability of an air conditioner at home and abroad: firstly, a traditional method based on the assumption that the functional relationship of parts or components obeys a series model is adopted, and the estimation accuracy of the method is poor due to the fact that a large error exists between the series model and the actual functional relationship of an air conditioning system; and secondly, field fault maintenance data obtained by after-sales service is used and is estimated by applying various statistical theories or methods, and the mode not only needs long-term accumulation of maintenance data, but also cannot be applied to the prediction and distribution of the maintainability of the product design stage because the mode cannot reflect the functional relationship between the maintainability of the air conditioning system and parts, components and units thereof.
Disclosure of Invention
The invention aims to provide a maintainability assessment method, which is characterized in that a maintainability analysis calculation model and an assessment method of a wall-mounted air conditioner complete machine system are derived by using a Markov chain theory on the basis of analyzing the physical structure relationship and functions of the wall-mounted air conditioner complete machine system, so that the maintainability level of the air conditioner system can be timely, conveniently and effectively analyzed and estimated in the design, manufacture and use processes of an air conditioner product.
The purpose of the invention is realized by adopting the following technical scheme. The method for evaluating the maintainability of the wall-mounted air-conditioning system is characterized by comprising the following steps of:
1) analyzing the working principle of the air conditioning system, and establishing a maintenance physical model of the system:
1.1, analyzing the functional structure relationship of the air conditioning system, and establishing a functional structure block diagram consisting of a control component, a cooling and heating component, an air path component, a frame component and a switch unit;
1.2 establishing a maintenance physical model consisting of a maintainer, a switch unit, a branch unit I and a branch unit II according to a maintenance mode commonly adopted by the air conditioning system;
2) analyzing the influence mode of the switch unit on the air conditioning system, and determining all possible states of the air conditioning system:
2.1 the analysis determines two modes of influence of the switching cell: the first mode of influence is that when the switch unit fails, the air conditioning system does not immediately fail, and when the working branch needs to be switched, the switch unit cannot complete the switching task, so that the air conditioning system fails; the second mode of influence is that a failure of the switching unit immediately results in a failure of the air conditioning system;
2.2 for the first influence mode of the switch unit, the fact that the air conditioning system is possibly in nine states at the time t can be analyzed;
2.3 for the second mode of influence of the switching unit, it can be analyzed that the air conditioning system may be in five states at time t.
3) Respectively determining the transition probability of the air conditioning system from one state to any other state under different influence modes of the switch unit:
3.1 determining the transition probability of the air conditioning system from one state to any one of the other eight states in nine possible states at time t of the first influence mode of the switch unit;
3.2 determining the transition probability of the air conditioning system from one state to any one of the other four states in five possible states at the time t of the air conditioning system in the second influence mode of the switch unit;
4) establishing a maintainability mathematical model of the air conditioning system:
4.1, relevant requirements of the air conditioning system are clarified;
4.2 determining the failure Rate λ of the parts or Components that make up the Components of the air-conditioning SystemijAnd mean time to repair MTTRijWherein j is the number of parts or components constituting the component i, wherein: 1, 2, 3, 4 and K, wherein 1 is a control component, 2 is a cooling and heating component, 3 is an air path component, 4 is a frame component, and K is a switch unit;
4.3 calculating the failure rate of the air conditioning system switch unit:
and failure rate of tributary unit I:
and the failure rate of tributary unit II:
4.4 calculating the repair rate of the air conditioning system switch unit:
and repair rate of tributary unit I:
and the repair rate of the tributary unit II:
4.5 calculate the mean time between failure of the air conditioning system in the first mode of influence of the switching unit:
and average maintenance time:
in the formula: d is the ratio of the time of the air conditioning system working in the first branch circuit to the total working time of the air conditioning system, and 1-d is the ratio of the time of the air conditioning system working in the second branch circuit to the total working time of the air conditioning system;
4.6 calculate the mean time between failure of the air conditioning system in the second mode of influence of the switching unit:
and average maintenance time:
5) establishing an evaluation program:
5.1 determining failure rates λ of parts or components constituting parts of air-conditioning systemsijMTTR mean time to repairijAnd a system operating parameter d;
5.2 calculating the failure rates lambda of the switch unit, the branch unit I and the branch unit II respectively according to the formulas (1), (2) and (3) in the step 4)k、λI、λII；
5.3 calculating the repair rate α of the switch unit, the branch unit I and the branch unit II respectively according to the formulas (4), (5) and (6) in the step 4)k、αI、αII；
5.4 calculating the mean time between failure MTBF of the air conditioning system in the first influencing mode of the switching unit from the equations (7) and (8) in step 4), respectivelySMTTR mean time to repairS；
5.5 calculating the mean time between failure MTBF of the air conditioning system in the second influence mode of the switching unit from equations (9) and (10) in step 4) respectively'SMTTR mean repair time'S。
Further, the related requirements include:
1) once a certain part or component forming the air conditioning system fails, a repairman immediately maintains the part or component, and if another part or component also fails, the repairman needs to wait for maintenance;
2) if the branch unit I and the branch unit II or one branch unit and the switch unit are in a fault or maintenance state at the same time, the air conditioning system works again after all the units are repaired;
3) the maintenance of all parts or components of the air conditioning system is independent, and the maintenance time follows the exponential distribution;
4) the faults of all parts or components of the air conditioning system are subjected to exponential distribution, the fault modes are mutually independent, and the refrigerating and heating components only have faults in the working state;
5) the air conditioning system is in a normal state during initial work;
6) the switching time of the air conditioning system between the first branch and the second branch is ignored.
The method for evaluating the maintainability of the wall-mounted air-conditioning system establishes the functional relationship between the parts or components, units and the maintainability index of the system, so that the prediction and distribution of the maintainability can be possible to be developed in the design and development process of the air-conditioning system, and the method can also be applied to the prediction of the maintainability level of the air-conditioning system after installation and use, and provides a basis for formulating a scientific after-sale maintenance strategy.
Drawings
FIG. 1 is a functional block diagram of a wall-mounted air conditioning system according to the present invention;
FIG. 2 is a physical model of the maintenance of the wall-mounted air conditioning system of the present invention;
FIG. 3 shows MTBF in accordance with the present inventionS、MTBF′SAnd MTBFSThe change rule along with the parameter d;
FIG. 4 shows MTTR in the present inventionS、MTTR′SAnd MTTRSThe change rule along with the parameter d.
Detailed Description
The invention is further illustrated by the following figures and examples. See fig. 1-4.
The method for evaluating the maintainability of the wall-mounted air-conditioning system comprises the following specific implementation steps of:
through analysis of the functional structure relationship of the air conditioning system, a functional structure block diagram composed of five component modules including a control component 1, a cooling and heating component 2, an air path component 3, a frame component 4 and a switch unit K is established, as shown in fig. 1.
According to the maintenance mode commonly adopted by the existing air conditioning system, a maintenance physical model consisting of a maintainer, a switch unit K, a branch unit I and a branch unit II is established, as shown in figure 2.
by analysis, it can be determined that there are two modes of influence of the switch unit K: the first influence mode is that when the switch unit K fails, the air conditioning system does not immediately fail, and when the working branch needs to be switched, the switch unit K cannot complete the switching task, so that the air conditioning system fails; in a second influence mode, the failure of the switch unit K immediately causes the failure of the air conditioning system;
for the first mode of influence of the switching unit K, all nine possible states of the air conditioning system at time t can be analyzed, as shown in table 1 below:
TABLE 1 State of air conditioning system at time t that causes failure when the fail switch unit is switched
| State sequence number | Branching unit I | Branching unit II | Switch unit K | |
| 3 | Normal operation | Cold storage | Fault of | |
| 2 | Cold storage | Normal operation | Fault of | |
| 1 | Normal operation | Cold storage | Normal operation | |
| 0 | Cold storage | Normal operation | Normal operation | Normal operation |
| -1 | Repairing | Cold storage | Normal operation | Fault of |
| -2 | Cold storage | Repairing | Normal operation | Fault of |
| -3 | Cold storage | Repairing | Waiting for repair | Fault of |
| -4 | Repairing | Cold storage | Waiting for repair | Fault of |
| -5 | Any state | Any state | Repairing | Fault of |
For the second mode of influence of the switching unit K, all five possible states of the air conditioning system at time t can be analyzed, as shown in table 2 below:
table 2 state of air conditioning system in which failure of switching unit immediately causes failure at time t
| State sequence number | Branching unit I | Branching unit II | Switch unit K | |
| 1 | Normal operation | Cold storage | Normal operation | |
| 0 | Cold storage | Normal operation | Normal operation | Normal operation |
| -1 | Repairing | Cold storage | Normal operation | Fault of |
| -2 | Cold storage | In repair | Normal operation | Fault of |
| -3 | Any state | Any state | Repairing | Fault of |
for the first influence mode of the switch unit K, nine states which the air conditioning system can be in at the time t can be determined, and the state transition probability p of the system from a certain state i to any state j in other eight states in the time delta t after the time t can be determinedij(Δt)：
p3,-5(Δt)＝d(1-λIIΔt)+o(Δt)，p3,-3(Δt)＝λIIΔt+o(Δt)，
p3,3(Δt)＝(1-d)(1-λIIΔt)+o(Δt)，p3,j(Δt)＝o(Δt)(j＝2,1,0，-1，-2，-4)；
p2,-5(Δt)＝(1-d)(1-λIIΔt)+o(Δt)，p2,-4(Δt)＝λIΔt+o(Δt)，
p2,2(Δt)＝d(1-λIΔt)+o(Δt)，p2,j(Δt)＝o(Δt)(j＝3,1,0，-1，-2，-3)；
p1,-1(Δt)＝λIIΔt+o(Δt)，p1,0(Δt)＝d(1-λIIΔt-λkΔt)+o(Δt)，
p1,1(Δt)＝(1-d)(1-λIIΔt-λkΔt)+o(Δt)，p1,3(Δt)＝λkΔt+o(Δt)，
p1,j(Δt)＝o(Δt)(j＝2，-2，-3，-4，-5)；
p0,-2(Δt)＝λIΔt+o(Δt)，p0,0(Δt)＝d(1-λIΔt-λkΔt)+o(Δt)，
p0,1(Δt)＝(1-d)(1-λIΔt-λkΔt)+o(Δt)，p0,2(Δt)＝λkΔt+o(Δt)，
p0,j(Δt)＝o(Δt)(j＝3，-1，-3，-4，-5)；
p-1,-1(Δt)＝1-αIIΔt+o(Δt)，p-1,0(Δt)＝dαIIΔt+o(Δt)，
p-1,1(Δt)＝(1-d)αIIΔt+o(Δt)，p-1,j(Δt)＝o(Δt)(j＝3，2，-2，-3，-4，-5)；
p-2,-2(Δt)＝1-αIΔt+o(Δt)，p-2,0(Δt)＝dαIΔt+o(Δt)，
p-2,1(Δt)＝(1-d)αIΔt+o(Δt)，p-2,j(Δt)＝o(Δt)(j＝3，2，-1，-3，-4，-5)；
p-3,-5(Δt)＝αIIΔt+o(Δt)，p-3,-3(Δt)＝1-αIIΔt+o(Δt)，
p-3,j(Δt)＝o(Δt)(j＝3，2，1，0，-1，-2，-4)；
p-4,-5(Δt)＝αIΔt+o(Δt)，p-4,-4(Δt)＝1-αIΔt+o(Δt)，
p-4,j(Δt)＝o(Δt)(j＝3，2，1，0，-1，-2，-3)；
p-5,-5(Δt)＝1-αkΔt+o(Δt)，p-5,0(Δt)＝dαkΔt+o(Δt)，
p-5,1(Δt)＝(1-d)αkΔt+o(Δt),p-5,j(Δt)＝o(Δt)(j＝3，2，-1，-2，-3，-4)。
In the formula: d is the ratio of the time of the air conditioning system working in the first branch circuit to the total working time of the air conditioning system, and 1-d is the ratio of the time of the air conditioning system working in the second branch circuit to the total working time of the air conditioning system; lambda [ alpha ]k、λI、λII、αk、αI、αIIThe failure rates of the switch unit K, the branch unit I and the branch unit II are respectively:
and the repair rate:
in the formula: when m is k, i is k; when m is I, I is not equal to k; when m is II, i is not equal to 2, k; lambda [ alpha ]ij、MTTRijThe failure rate and the average repair time of the component or component j of each component i (i ═ 1, 2, 3, 4, k) are respectively.
As above, for the second mode of influence of the switching unit K, the five states that the air conditioning system may be in at time t can determine the state transition probability p 'that the system transitions from a certain state i to any one state j of the other four states within time Δ t after time t'ij(Δt)。
Step 4, establishing a maintainability mathematical model of the air conditioning system:
in order to facilitate the analysis of maintainability of the air conditioning system, the characteristics of the air conditioning system are defined as follows:
① once a part or component of the system is out of order, the repairman can repair it immediately, if another part or component is out of order, the repairman must wait for the repair;
② if two branch units, or one branch unit and the switch unit K are in fault or maintenance state at the same time, the air conditioning system will work again after all units are repaired;
③ the maintenance of all parts or components of the air conditioning system is independent, the maintenance time is distributed according to index;
④ the failure modes of all parts or components of the air conditioning system are independent, the failures obey the exponential distribution, and the refrigeration and heating components only fail in the working state;
⑤ the air conditioning system is in normal state when it is initially working;
⑥ the switching time of the air conditioning system between the first branch and the second branch is negligible.
According to the Markov chain correlation theory, the transfer rate matrix of the system can be obtained:
in the formula:
order to
pj(t)＝p{N(t)＝j}；
Representing the probability that the system is in state j at time t.
Solving a system of equations:
the following can be obtained:
in the formula:
thus, the steady-state availability of the system is obtained:
and the steady state failure rate of the system is:
substituting the parameters related to the formula (3) into the above formula can obtain:
thus, the mean time between failure and operation of the system is determined:
and average maintenance time:
in the same way, the mean time between failure and operation of the air conditioning system in the second mode of influence of the switching unit K can be determined:
and average maintenance time:
5.1 determining failure rates λ of parts or components constituting parts of air-conditioning systemsijMTTR mean time to repairijAnd a system operating parameter d;
5.2 calculating the failure rates lambda of the switch unit K, the branch unit I and the branch unit II respectively according to the formula (1)k、λI、λII；
5.3 calculating repair rates α of switch unit K, branch unit I and branch unit II from equation (2) respectivelyk、αI、αII；
5.4 will lambdak、λI、λIIAnd αk、αI、αIISubstituting into the formulas (4) and (5) respectively to obtain the Mean Time Between Failures (MTBF) of the air conditioning system in the first influence mode of the switch unit KSAnd mean time to repair MTTRS；
5.5 will lambdak、λI、λIIAnd αk、αI、αIISubstituting into the formulas (6) and (7) respectively to obtain the Mean Time Between Failures (MTBF) of the air conditioning system in the second influence mode of the switch unit KS'and average repair time MTTR'S。
Example (b):
the maintainability model of the air-conditioning system and the implementation program are applied to the maintainability prediction of a wall-mounted air conditioner of a certain model, and the failure rate and average maintenance time data of components or parts are shown in the following table 1.
TABLE 1 air-conditioning system parts or components failure rate and average maintenance time data (time unit: working day)
| System component | Details or components | λij | MTTRij |
| Switch unit K | Controller | 6.26667×10-6 | 3 |
| |
Power supply signal wire | 1.86239×10-6 | 1 |
| Transformer device | 1.04556×10-7 | 1 | |
| Remote controller | 3.03206×10-6 | 1 | |
| Environmental temperature sensing head | 3.39800×10-7 | 1 | |
| Pipe temperature sensing head | 1.88850×10-6 | 1 | |
| Display panel | 5.16233×10-7 | 3 | |
| Receiver with a plurality of receivers | 1.56833×10-7 | 1 | |
| Refrigerating and |
Condenser | 9.47500×10-7 | 3 |
| Evaporator with a heat exchanger | 7.12278×10-7 | 3 | |
| Compressor starting capacitor | 3.92078×10-7 | 1 | |
| Compressor with a compressor housing having a plurality of compressor blades | 2.96672×10-6 | 3 | |
| One-way valve | 1.30694×10-8 | 3 | |
| Main capillary | 4.24750×10-7 | 1 | |
| Temperature controller | 2.61383×10-8 | 1 | |
| Electric heating tube | 2.48317×10-7 | 3 | |
| Filter | 7.18833×10-8 | 3 | |
| Connecting pipeline | 3.16278×10-6 | 1 | |
| Two-way stop valve | 2.02572×10-7 | 3 | |
| Three-way stop valve | 3.59406×10-7 | 3 | |
| Solenoid valve coil | 3.92078×10-8 | 3 | |
| Four-way reversing valve | 1.22850×10-6 | 3 | |
| |
Cross-flow fan blade | 3.09739×10-6 | 3 |
| Plastic packaging motor | 2.74456×10-7 | 3 | |
| Air guide mechanism | 3.79011×10-7 | 3 | |
| Stepping motor | 5.88111×10-7 | 3 | |
| Fan starting capacitor | 9.80167×10-8 | 1 | |
| Axial flow fan blade | 4.31283×10-7 | 3 | |
| Iron-clad motor | 4.63961×10-7 | 3 | |
| Frame part 4 | Inner machine frame | 3.16272×10-6 | 3 |
The data in table 1 are substituted into formulas (1) and (2), and the failure rate and the repair rate of each unit of the two-branch circulation allocation system can be respectively calculated, as shown in table 2.
Table 2 data of each unit of two branch circulation allocation system
| Related parameter | Branching unit I | Branching unit II | Switch unit K |
| Failure rate of cell | λI＝3.07845×10-5 | λII＝1.99893×10-5 | λk＝6.26667×10-6 |
| Cell repair rate | αI＝4.95010×10-1 | αII＝5.28600×10-1 | αk＝3.33333×10-1 |
And substituting the data in the table 2 into the expressions (4) to (7) to respectively obtain the average non-fault working time and the average maintenance time of the system, wherein the first influence mode of the switch unit K is that the switch unit K fails and the system does not immediately fail:
and a second mode of influence of the switching unit K, i.e. a failure of the switching unit K, the mean time between failure-free operation and mean time between maintenance of the system with immediate failure:
in the conventional maintainability estimation method, the maintenance of components or parts constituting each unit of the system is regarded as an independent maintenance item, and the average maintenance time of the whole system is as follows:
by substituting the data in Table 1 into the above equation, the following can be obtained:
MTTR″Sbecoming 2.18589 (workday) (10)
When the functional relationship between the system and the unit, between the unit and each component or part obeys the series model, the failure rate of the system is as follows:
mean time to failure of the system:
according to the literature of reliability prediction and distribution model and application research of wall-mounted air-conditioning system[1]The research conclusion can be concluded that the failure rate of the whole air conditioner system is as follows:
λ″S＝(2.62560+1.07952×d)×10-5；
substituting equation (11), the average no-fault operating time of the air conditioning system can be determined:
according to the formulae (8), (9), (10) and (12), FIG. 3 shows MTBFS、MTBF′SAnd MTBFSThe variation law with the parameter d is shown in FIG. 4, which shows the MTTRS、MTTR′SAnd MTTRSThe change rule along with the parameter d; in Table 3, the partial values of d are given in MTBFS、MTTRS、MTBF′S、MTTR′S、MTBF″SAnd MTTRSThe estimation result of (2).
TABLE 3 mean time to failure and mean time to repair of air conditioning system at different values of d
As can be seen from the data in fig. 3, fig. 4 and table 3, as the value of the operation ratio d increases, the mean time between failures of the air conditioning system in different situations decreases, which reflects that the cooling and heating components have a failure with the increase of the operation time and thus the possibility of system failure increases. For the second influence mode of the switch unit K, namely the switch influence mode that the system fault is immediately caused by the switch fault, the second influence mode is essentially that the functional relation of all units, parts or components of the system obeys a series model, the average fault-free work and the average maintenance time of the system calculated based on the Markov chain theory have excellent consistency with the result obtained by the traditional estimation method based on the assumption of the series model, two curves of the average fault-free work time are basically consistent, the difference of the two curves of the average maintenance time is extremely small, and the maximum relative error of each index is less than 3% under the same operation ratio d value, thereby proving the correctness of the method and the model provided by the invention.
Compared with the second influence mode of the switch unit K, the influence mode of the fault switch unit K, namely the first influence mode, only leads to system fault when the function is switched, the switch influence mode is closer to the practical engineering, the system has higher mean time of no fault work time for the same running ratio d value, and the mean time of no fault work time is prolonged by more than 42%.
Firstly, establishing a maintenance physical model of the system through analyzing the working principle of the air conditioning system, analyzing the influence mode of a switch unit on the system, and determining all possible states of the system; secondly, determining the transition probability of the system from one state to any other state under different influence modes of the switch unit, and further establishing a mathematical model of system maintainability by applying a Markov chain theory; and finally, obtaining a formula for predicting the average fault-free working time and the average maintenance time of the evaluation system, and establishing an evaluation program on the basis of the formula.
The invention establishes the functional relationship between the parts or components and units of the wall-mounted air-conditioning system and the system maintainability index, so that the maintainability prediction and distribution can be possible to be developed in the design and development process of the air-conditioning system, and the invention can also be used for predicting the maintainability of the air-conditioning system after installation and use, and provides a decision basis for making a scientific after-sale maintenance strategy.
Reference documents:
[1] reliability prediction and distribution model of Liuweidong, Liuyang, Zhang Fang, Wanghui and Li Jie wall-hanging type air-conditioning system and application research [ J ]. industrial engineering and management 2016, 21 (1): 143-149.
Claims (2)
1. A method for evaluating maintainability of a wall-mounted air-conditioning system is characterized by comprising the following steps:
1) analyzing the working principle of the air conditioning system, and establishing a maintenance physical model of the system:
1.1, analyzing the functional structure relationship of the air conditioning system, and establishing a functional structure block diagram consisting of a control component, a cooling and heating component, an air path component, a frame component and a switch unit;
1.2 establishing a maintenance physical model consisting of a maintainer, a switch unit, a branch unit I and a branch unit II according to a maintenance mode commonly adopted by the air conditioning system;
2) analyzing the influence mode of the switch unit on the air conditioning system, and determining all possible states of the air conditioning system:
2.1 the analysis determines two modes of influence of the switching cell: the first mode of influence is that when the switch unit fails, the air conditioning system does not immediately fail, and when the working branch needs to be switched, the switch unit cannot complete the switching task, so that the air conditioning system fails; the second mode of influence is that a failure of the switching unit immediately results in a failure of the air conditioning system;
2.2 for the first influence mode of the switch unit, the fact that the air conditioning system is possibly in nine states at the time t can be analyzed;
2.3 for the second influence mode of the switch unit, five states of the air conditioning system at the time t can be analyzed;
3) respectively determining the transition probability of the air conditioning system from one state to any other state under different influence modes of the switch unit:
3.1 determining the transition probability of the air conditioning system from one state to any one of the other eight states in nine possible states at time t of the first influence mode of the switch unit;
3.2 determining the transition probability of the air conditioning system from one state to any one of the other four states in five possible states at the time t of the air conditioning system in the second influence mode of the switch unit;
4) establishing a maintainability mathematical model of the air conditioning system:
4.1, relevant requirements of the air conditioning system are clarified;
4.2 determining the constituent voidsFailure rate lambda of parts or components of regulating systemsijAnd mean time to repair MTTRijWherein j is the number of parts or components constituting the component i, wherein: 1, 2, 3, 4 and K, wherein 1 is a control component, 2 is a cooling and heating component, 3 is an air path component, 4 is a frame component, and K is a switch unit;
4.3 calculating the failure rate of the air conditioning system switch unit:
and failure rate of tributary unit I:
and the failure rate of tributary unit II:
4.4 calculating the repair rate of the air conditioning system switch unit:
and repair rate of tributary unit I:
and the repair rate of the tributary unit II:
4.5 calculate the mean time between failure of the air conditioning system in the first mode of influence of the switching unit:
and average maintenance time:
in the formula: d is the ratio of the time of the air conditioning system working in the first branch circuit to the total working time of the air conditioning system, and 1-d is the ratio of the time of the air conditioning system working in the second branch circuit to the total working time of the air conditioning system;
4.6 calculate the mean time between failure of the air conditioning system in the second mode of influence of the switching unit:
and average maintenance time:
5) establishing an evaluation program:
5.1 determining failure rates λ of parts or components constituting parts of air-conditioning systemsijMTTR mean time to repairijAnd a system operating parameter d;
5.2 calculating the failure rates lambda of the switch unit, the branch unit I and the branch unit II respectively according to the formulas (1), (2) and (3) in the step 4)k、λI、λII；
5.3 calculating the repair rate α of the switch unit, the branch unit I and the branch unit II respectively according to the formulas (4), (5) and (6) in the step 4)k、αI、αII；
5.4 calculating the mean time between failure MTBF of the air conditioning system in the first influencing mode of the switching unit from the equations (7) and (8) in step 4), respectivelySMTTR mean time to repairS；
5.5 calculating the average of the air conditioning system in the second influencing mode of the switching unit from the equations (9) and (10) in step 4), respectivelyNo fault working time MTBF'SMTTR mean repair time'S。
2. The wall-hanging air conditioning system serviceability assessment method of claim 1, wherein said relevant requirements comprise:
1) once a certain part or component forming the air conditioning system fails, a repairman immediately maintains the part or component, and if another part or component also fails, the repairman needs to wait for maintenance;
2) if the branch unit I and the branch unit II or one branch unit and the switch unit are in a fault or maintenance state at the same time, the air conditioning system works again after all the units are repaired;
3) the maintenance of all parts or components of the air conditioning system is independent, and the maintenance time follows the exponential distribution;
4) the faults of all parts or components of the air conditioning system are subjected to exponential distribution, the fault modes are mutually independent, and the refrigerating and heating components only have faults in the working state;
5) the air conditioning system is in a normal state during initial work;
6) the switching time of the air conditioning system between the first branch and the second branch is ignored.
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