The present application claims priority from Japanese Patent application serial no. 2018-167562 filed on Sep. 7, 2018, the content of which is hereby incorporated by reference into this application.
The present invention relates to a failure mode estimation system for assisting a maintenance work of a device by a maintenance worker, by estimating and notifying a failure mode of a stopped device.
Maintenance work for maintaining a normal condition of a device is indispensable for devices required with continuous operation for a long time such as gas engines, elevators, mining equipment, construction equipment, and pumps. In addition, when the device fails and stops, it is required to promptly investigate a cause of the failure and take countermeasures (cleaning, parts replacement, repair, and the like) according to the cause of the failure. In investigating the cause of failure, it is particularly of importance to check a state of each part of the device and correctly specify a failure type (hereinafter referred to as “failure mode”) of the device in order to take appropriate countermeasures.
Here, as an invention that has automated specification of a failure mode, the invention described in JP 2009-223362 A is known. The abstract of JP 2009-223362 A describes “a processing process of software of an image forming apparatus is recorded (S300), a log in response to the occurrence of a fault is acquired (S302 and S304), and a sub cause and effect network is created (S320) and held (S330). A management center collects the sub cause and effect network of each image forming apparatus periodically (S331 to S336). The collected sub cause and effect networks are classified by a model, embedded into an existing diagnostic model by a model to optimize the diagnostic model, and presented to the relevant devices (S360, S361, and S370). The image forming apparatus performs diagnosis by applying a received aptitude diagnostic model (S380)”.
As described above, JP 2009-223362 A introduces a technique for estimating what kind of failure mode is occurring from a probability, with use of a model in which a failure probability is defined for each state of each part of the device and for each operation history of a user who uses the device. Then, there is disclosed a technique capable of temporary update in accordance with an actual situation of a failure situation in a market by setting a failure probability from knowledge and experience of a designer of a device and reliability information, and by updating an occurrence probability of a failure mode whose occurrence frequency exceeds a certain value.
However, since JP 2009-223362 A is for updating a diagnostic model of a failure mode whose occurrence frequency exceeds a certain threshold value, a considerable time (e.g., one year) may be required for updating a diagnostic model of a failure mode with a low occurrence frequency.
Therefore, even if the technique of JP 2009-223362 A is used, it is not possible to improve a specification accuracy for all failure modes, and the diagnostic model is left unused for a long period of time without being updated in a case where an initial value of a diagnostic model of a failure mode with a low occurrence frequency is inaccurate. This causes a problem that a failure mode corresponding to such a diagnostic model is left untouched for a long period of time with a low specification accuracy.
Therefore, in the present invention, there is provided a failure mode estimation system capable of improving an estimation accuracy for a failure mode regardless of an occurrence probability of the failure mode, by appropriately improving a diagnostic model when failure mode estimation fails.
In order to solve the above problem, a failure mode estimation system of the present invention estimates a failure mode of a device on the basis of an inputted state of the device. Further, the failure mode estimation system includes: a failure mode estimation unit that estimates a failure mode of the device on the basis of the inputted state of the device and a table in which correspondence between a failure mode of the device and an estimation standard is registered; and an update unit that updates the estimation standard registered in the table when a failure mode estimated by the failure mode estimation unit is incorrect.
According to the present invention, there is provided a failure mode estimation system capable of improving an estimation accuracy for a failure mode regardless of an occurrence probability of the failure mode, by appropriately improving a diagnostic model when failure mode estimation fails.
Hereinafter, a failure mode estimation system 10 according to one embodiment of the present invention will be described with reference to the drawings.
The device 2 is any maintenance target device such as a generator, construction machinery, or a medical device that is required to be continuously driven for a long time. Hereinafter, a description is given on assumption that the device 2 is a pump, and a failure mode to be estimated is “abnormal vibration in bearing”, “impeller failure”, “seal leakage”, and the like. When the device 2 stops, the maintenance worker 1 can obtain an estimation result of a failure mode by the server 4, by checking a state of each part of the device 2 and inputting the result to the terminal 3 described later. Although
The terminal 3 is a lightweight tablet or the like that the maintenance worker 1 can easily carry, and is provided with a display unit 30 such as a liquid crystal display, an input unit 31 such as a touch display, and a communication unit 32 that communicates with the server 4 via a public line.
The server 4 receives a check result of the device 2 inputted to the terminal 3 by the maintenance worker 1, estimates the failure mode of the device 2 on the basis of the check result, and then returns the estimation result to the terminal 3. Further, if the estimation result is incorrect, the server 4 improves an estimation accuracy for subsequent failure modes by correcting the estimation standard such as “failure probability” in a diagnostic model used for estimating the failure mode, on the basis of a correct failure mode provided from the maintenance worker 1.
This server 4 includes, as shown in
The server 4 is actually a computer including a computing device such as a CPU, a main storage device such as a semiconductor memory, an auxiliary storage device such as a hard disk, and hardware such as a communication device. Then, each function of the above-described failure mode estimation unit 40 and the like is realized by the computing device executing the program loaded in the main storage device while referring to a database recorded in the auxiliary storage device. In the description below, such known technologies are appropriately omitted.
Next, with reference to
Next, a description will be given to a method in which the failure mode estimation system 10 estimates a failure mode of the device 2 on the basis of each table described above after the maintenance worker 1 visits the operation site of the stopped device 2, and details on a method for correcting the diagnostic model in a case where the estimation result is incorrect, with reference to the flowcharts of
First, the flowchart of
In step S2, the maintenance worker 1 inputs a check result according to the state of the device 2. For example, the maintenance worker 1 checks as shown in a check box 11c′ of a display example 30b of
First, in step S3a, the failure probability table 46 is searched with the check box 11c′ inputted in step S2 as a search key. Specifically, a check item checked by the maintenance worker 1 (checked in the column of the check box 11c′ in
In step S3b, the probability values temporarily stored in the temporary storage unit 45 are summed for each failure mode. For example, in a case where a table of
In step S3c, it is determined whether or not a failure mode with a probability value increasing with elapsed years is included in the extracted failure modes. Specifically, with the failure mode 45b in the table of
When the value of the probability increase rate 49b is registered, the elapsed years of the device 2 is multiplied by the increase rate 49b to calculate an increment width of the failure probability, in step S3d. For this purpose, firstly, the maintenance worker 1 acquires the installation date of the device 2 from the operation condition C3 of the device management table 48, with the operation site and the device ID inputted in
In step S3e, the increment width obtained in step S3d is added to the corresponding failure mode in the table of
In step S3f, a failure mode with the largest sum of the probability values is extracted and presented as an estimation result of the failure mode. In the example of
In step S4, the maintenance worker 1 determines whether a fault has occurred in the device 2 in the first place. When the failure has not been confirmed, a button 12c of the display example 30c in
In step S10, the probability update unit 42 downwardly corrects the probability 46c registered in the failure probability table 46 by a predetermined decrement width. This is because the probability 46c is considered to be too high in a case where the failure mode has not been actually confirmed despite the failure mode estimated by the failure mode estimation unit 40. The decrement width of the probability 46c is calculated for each checked item as follows, with use of the decrease coefficient kd registered in the probability update table 49.
Decrement width=decrease coefficient kd×(number of mismatches between assumed condition and operation condition) (Expression 1)
In Expression 1, the decrease coefficient kd may be the same in the check items of the same failure mode. For example, in a case of downward correction of the probability of the failure mode “abnormal vibration in bearing” presented in the estimation result display field 12a of the display example 30c of
Decrement width of failure mode “abnormal vibration in bearing”=0.005×1=0.005 (Expression 2) This decrement width “0.005” is subtracted from, in this example, the probability values “0.60” and “0.25” of “heat is generated in bearing” and “sharp sound occurs” among the probability 46c of the failure probability table 46 in
Whereas, when a failure can be confirmed in step S4, the maintenance worker 1 applies, to the device 2, a countermeasure (cleaning, parts replacement, repair, or the like) required for fixing the failure, on the basis of the failure mode (e.g., “abnormal vibration in bearing”) estimated by the failure mode estimation unit 40, in step S5. Since it is possible to check what kind of countermeasure is required from a maintenance work manual and the like on the basis of the estimated failure mode, even an unskilled maintenance worker 1 can implement an appropriate countermeasure according to the failure mode.
Thereafter, in step S6, the maintenance worker 1 determines whether or not the failure of the device 2 has been fixed as a result of the countermeasure specified in the maintenance work manual or the like. When the device 2 is fixed, it can be determined that the failure mode estimated by the failure mode estimation unit 40 is appropriate, and it is not necessary to modify the failure probability table 46. Therefore, the main routine is ended with the current failure probability table 46 maintained as it is. Whereas, when the device 2 has not been fixed by the countermeasure applied in step S5, it can be determined that the failure mode estimated by the failure mode estimation unit 40 is incorrect, and it is required to correct the failure probability table 46 that has led to the incorrect conclusion. Therefore, the process proceeds to step S7 and the subsequent steps in order to correct the probability 46c of the failure probability table 46.
First, in step S7, the maintenance worker 1 estimates a failure mode that is considered to be correct, without relying on this system. For example, an experienced maintenance worker 1 may estimate the correct failure mode by investigating the device 2 in detail, while an unskilled maintenance worker 1 may estimate the correct failure mode while consulting with an expert on a telephone or the like.
In step S8, the maintenance worker 1 sends the failure mode estimated in step S7 to the server 4 via the terminal 3. For this purpose, the maintenance worker 1 presses a button 12d of the display example 30c of
In step S9, the maintenance information comparison unit 41 and the probability update unit 42 execute a subroutine SUB02 for correcting the probability of the failure mode on the basis of the failure mode inputted in step S8. This subroutine SUB02 will be described with reference to
First, in step S9a, it is determined whether or not the correct failure mode inputted by the maintenance worker 1 is a failure mode in which the probability value increases with elapsed years. This can be determined by whether or not a value is present in the increase rate 49a of the probability of the correct failure mode, in the probability update table 49. When the value is present, the process proceeds to step S9g, otherwise proceeds to step S9b.
In a case where the correct failure mode is a failure mode in which the probability value does not increase with the elapsed years, the increment width for upward correction of the probability of the correct failure mode is calculated by the following Expression 3, in step S9b. This is the same calculation method as Expression 1 in step S10, merely with the decrease coefficient kd changed to the increase coefficient ki.
Increment width=increase coefficient ki×(number of mismatches between assumed condition and operation condition) (Expression 3)
In step S9c, the increment width obtained in step S9b is added to a value of the row of the check item associated with the correct failure mode, among the probability 46c of the failure probability table 46 in
Whereas, in a case where the correct failure mode is a failure mode in which the probability value increases with elapsed years, the increment width of the probability increase rate 49b of the probability update table 49 of
Next, in step S9d, it is determined whether or not an incorrect failure mode estimated by the failure mode estimation unit 40 is a failure mode in which the probability value increases with elapsed years. This can be determined by whether a value is present in the increase rate 49a of the incorrect failure mode, in the probability update table 49. When the value is present, the process proceeds to step S9i, otherwise proceeds to step S9e.
In a case where the incorrect failure mode is a failure mode in which the probability value does not increase with elapsed years, a decrement width for downward correction of the probability of the incorrect failure mode is calculated in step S9e. This is the same calculation method as Expression 1 in step S10.
In step S9f, the decrement width obtained in step S9e is subtracted from a value of the row of the check item associated with the incorrect failure mode, among the probability 46c of the failure probability table 46 in
Whereas, in a case where the incorrect failure mode is a failure mode in which the probability value increases with elapsed years, the decrement width of the probability increase rate 49b of the probability update table 49 of
The subroutine SUB02 in
As described above, when the failure mode estimation unit 40 estimates an incorrect failure mode, the probability 46c of the failure probability table 46 or the probability increase rate 49b of the probability update table 49 corresponding to the incorrect failure mode is corrected downward, and the probability 46c of the failure probability table 46 or the probability increase rate 49b of the probability update table 49 corresponding to the correct failure mode inputted by the maintenance worker 1 is corrected upward, by performing the processing of the flowcharts of
That is, according to the failure mode estimation system of the present embodiment, it is possible to improve a specification accuracy for a failure mode regardless of an occurrence probability of the failure mode, by appropriately improving a diagnostic model when failure mode estimation fails.
Number | Date | Country | Kind |
---|---|---|---|
2018-167562 | Sep 2018 | JP | national |