Grab bucket diagnostic device

Abstract

To provide a grab bucket diagnostic device capable of presenting an accurate diagnosis result regarding each part of a grab bucket.SOLUTION: A grab bucket diagnostic device 21 includes: first to fourth flowmeters 13-16 each measuring a flow rate of working fluid flowing into / flowing out from a head side or a rod side of a hydraulic cylinder 4, a flow rate of the working fluid discharged by a hydraulic pump 7 or a return flow rate or a pressure gauge 17 measuring hydraulic pressure of the working fluid discharged from the hydraulic pump 7; a measurement time specification section 30 that specifies a measurement time predetermined with respect to each operation process; and a diagnosis section 26 that makes a diagnosis on the basis of a measurement value obtained by the first to fourth flowmeters 13-16 or the pressure gauge 17 at the measurement time in each operation process.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a grab bucket diagnostic device that determines whether or not there is a defect in a grab bucket. [Background technology]

[0002] Conventionally, a grab bucket equipped with a grab having a plurality of buckets (claws) driven by a hydraulic cylinder has been known (see Patent Document 1). The grab bucket of Patent Document 1 is equipped with a control unit that measures the value of current supplied to the hydraulic unit and performs arithmetic analysis. Based on the results of the arithmetic analysis, the control unit outputs a signal related to the opening and closing operation of the bucket, thereby detecting when the opening and closing of the bucket is complete, and controls operations related to the subsequent opening and closing operation of the bucket.

[0003] In such grab buckets, if the hydraulic unit, which is made up of a hydraulic cylinder and a hydraulic pump, begins to deteriorate, the amount of current in the power supply line to the hydraulic unit decreases and becomes smaller than its original value. Utilizing this, Patent Document 1 states that it is possible to diagnose the deterioration trend of the hydraulic unit. It also states that a temperature sensor, oil temperature sensor, etc. may be installed to detect abnormalities in the hydraulic unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-121873 Summary of the Invention [Problem to be solved by the invention]

[0005] However, while the grab bucket in Patent Document 1 is said to be capable of diagnosing deterioration of the hydraulic unit based on the amount of current in the power supply line to the hydraulic unit, and of detecting abnormalities in the hydraulic unit based on a temperature sensor, an oil temperature sensor, etc., it does not disclose any specific details regarding the target parts or diagnostic methods.

[0006] In view of the problems with the conventional technology, an object of the present invention is to provide a grab bucket diagnostic device that can accurately diagnose each part of the grab bucket. [Means for solving the problem]

[0007] The grab bucket diagnostic device of the present invention includes a diagnostic unit that diagnoses the presence or absence of a malfunction in a grab bucket having a plurality of buckets driven by hydraulic cylinders that operate with hydraulic oil discharged from a hydraulic pump.

[0008] The grab bucket operates through various operation steps, including an opening operation step for opening the bucket, an open state maintaining step for maintaining the bucket in an open state, a closing operation step for closing the bucket, a closed state maintaining step for maintaining the bucket in a closed state, and an idle circulation step in which hydraulic oil is not supplied to the hydraulic cylinder.

[0009] The grab bucket diagnostic device includes a first, second, third, or fourth flow meter that measures the flow rate of hydraulic oil flowing in and out of the head side or rod side of the hydraulic cylinder, the discharge flow rate of hydraulic oil discharged by the hydraulic pump, or the flow rate of hydraulic oil returning to the oil tank, or a pressure gauge that measures the oil pressure of the hydraulic oil discharged by the hydraulic pump.

[0010] The grab bucket diagnostic device also includes a timer for identifying the time of measurement by the first, second, third or fourth flow meter or the pressure meter, and a measurement time identifying unit for identifying the time of measurement for any one or more operation processes by using the timer to measure a predetermined time from the start of the operation process, the time being predetermined for each operation process.

[0011] The grab bucket diagnostic device also includes a diagnostic unit that diagnoses the presence or absence of a malfunction of the grab bucket based on the measurement value of the first, second, third or fourth flow meter or the pressure meter at the time of measurement in the operation process for which the time of measurement has been identified.

[0012] According to the present invention, the measurement time specifying unit specifies the measurement time by the first, second, third or fourth flow meter or pressure meter for each of one or more operation processes. Then, the presence or absence of a malfunction of the grab bucket is diagnosed based on the measurement value by the first, second, third or fourth flow meter or pressure meter at the measurement time in the operation process for which the measurement time has been specified.

[0013] In this way, diagnosis is performed based on the measurement values of the first, second, third or fourth flow meter or pressure meter during any one or more operating steps, so that accurate diagnosis can be performed for each part of the grab bucket. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram showing a grab bucket diagnosed by a grab bucket diagnostic device according to an embodiment of the present invention. FIG. [Figure 2] FIG. 2 is a hydraulic circuit diagram showing a hydraulic circuit of the grab bucket of FIG. 1. [Figure 3] 2 is a block diagram showing the configuration of a grab bucket diagnostic device that diagnoses the grab bucket of FIG. 1. FIG. [Figure 4] 3 is a timing chart showing how the amount of hydraulic oil in the hydraulic circuit of FIG. 2 changes in accordance with the progress of each operation step of the grab bucket of FIG. 1. [Figure 5] 4 is an explanatory diagram for explaining a method of specifying the time of measurement by a measurement time specifying unit of the grab bucket diagnostic device of FIG. 3. FIG. [Figure 6] 4 is a flowchart showing a measurement process performed by a measurement unit of the grab bucket diagnostic device of FIG. 3. [Figure 7] 4 is a diagram of a table showing an example of a diagnosis result by a diagnosing unit of the grab bucket diagnosing device of FIG. 3. FIG. [Figure 8] FIG. 8 is a table showing a continuation of the table of FIG. 7. [Figure 9] 4 is a flowchart showing a diagnostic process performed by a diagnostic unit of the grab bucket diagnostic device of FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows a grab bucket that is diagnosed by a grab bucket diagnosis device according to an embodiment of the present invention. As shown in Fig. 1, this grab bucket 1 has five buckets 3 that make up a grab 2. However, only two of the five buckets 3 are shown in the drawing. The five buckets 3 are arranged to form a regular pentagon on a horizontal plane.

[0016] Each bucket 3 is driven by a hydraulic cylinder 4 that operates with the hydraulic pressure of hydraulic oil supplied by a hydraulic pump. In this embodiment, a double-acting single-rod type hydraulic cylinder 4 is used.

[0017] The grab bucket 1 operates through the following operation steps: an opening operation step OP for opening the bucket 3, an open state maintaining step OM for maintaining the bucket 3 in an open state, a closing operation step CP for closing the bucket 3, a closed state maintaining step CM for maintaining the bucket 3 in a closed state, and an idle circulation step IP for not supplying hydraulic oil to the hydraulic cylinder 4 (see Figure 4).

[0018] Fig. 2 is a hydraulic circuit diagram showing the hydraulic circuit of the grab bucket 1. As shown in Fig. 2, this hydraulic circuit 5 includes an oil tank 6 and a hydraulic pump 7 that supplies oil from the oil tank 6 to the hydraulic cylinders 4 of each bucket 3. The hydraulic pump 7 is driven by a motor 8. The supply of hydraulic oil from the oil tank 6 to the hydraulic cylinders 4 and the return of the hydraulic oil to the oil tank 6 are controlled by a 4-port 3-position directional control valve (solenoid valve) 9.

[0019] This directional control valve 9 has ports A and B connected to the hydraulic cylinders 4, port P connected to the hydraulic pump 7, and port T connected to the oil tank 6. Port A is connected to the rod side of each hydraulic cylinder 4. Port B is connected to the head side of each hydraulic cylinder 4.

[0020] Oil flow path 10a extending from port A branches into two oil flow paths 10b and 10c at first branch point 11. Oil flow path 10b further branches into three oil flow paths 10b1 to 10b3, which are connected to the rod sides of three hydraulic cylinders 4. Oil flow path 10c further branches into two oil flow paths 10c1 and 10c2, which are connected to the rod sides of the other two hydraulic cylinders 4.

[0021] Oil flow path 10d extending from port B branches into two oil flow paths, 10e and 10f, at second branch point 12. Oil flow path 10e further branches into three oil flow paths 10e1 to 10e3, which are connected to the head sides of the three hydraulic cylinders 4. Oil flow path 10f further branches into two oil flow paths f1 and f2, which are connected to the head sides of the other two hydraulic cylinders 4.

[0022] A port P of the directional control valve 9 is connected to the discharge port of the hydraulic pump 7 via an oil flow path 10g. A port T is connected to the oil tank 6 via an oil flow path 10h.

[0023] A first flow meter 13 is provided in an oil flow path 10e1 connected to the head side of one hydraulic cylinder 4, measuring a head flow rate HD (see FIG. 4) which is the flow rate of hydraulic oil flowing out from the head side of the hydraulic cylinder 4. A second flow meter 14 is provided in an oil flow path 10b1 connected to the rod side of the first flow meter 13, measuring a rod flow rate RD which is the flow rate of hydraulic oil flowing out from the rod side of the hydraulic cylinder 4.

[0024] A third flow meter 15 is provided in the oil flow path 10g between the directional control valve 9 and the hydraulic pump 7, and measures the pump discharge rate PM, which is the flow rate of hydraulic oil discharged by the hydraulic pump 7. A fourth flow meter 16 is provided in the oil flow path 10h between the directional control valve 9 and the oil tank 6, and measures the return flow rate RT of hydraulic oil returning to the oil tank 6.

[0025] In addition, between the directional control valve 9 and the third flow meter 15 in the oil flow path 10g, there are provided a pressure gauge 17 for measuring the pump pressure PP, which is the pressure of the hydraulic oil discharged by the hydraulic pump 7, and a pressure switch 18 for detecting the completion of the opening and closing operation of the grab 2. The pressure switch 18 is provided via a filter 19 and a variable throttle valve 20.

[0026] When diagnosing the grab bucket 1, the first to fourth flow meters 13 to 16 and the pressure gauge 17 can be attached to the respective measurement locations with a single touch.

[0027] Fig. 3 shows the configuration of a grab bucket diagnostic device. As shown in Fig. 3, this grab bucket diagnostic device 21 includes a diagnostic control unit 22 that diagnoses the grab bucket 1 based on the measurement results from the first to fourth flow meters 13 to 16 and the pressure gauge 17. The diagnostic control unit 22 is made up of a computer, a program, etc.

[0028] The diagnosis control unit 22 includes a diagnosis drive unit 23 that drives the grab bucket 1 in order to diagnose the grab bucket 1, a measurement unit 24 that performs measurements necessary for diagnosis while the diagnosis drive unit 23 drives the grab bucket 1, a timer 25 that measures the time necessary for the measurements in the measurement unit 24, a diagnosis unit 26 that performs diagnostic processing of the grab bucket 1 based on the measurement data measured by the measurement unit 24, and an output unit 28 that displays the processing results by the diagnosis unit 26 on a monitor 27.

[0029] The diagnostic drive unit 23 controls the directional control valve 9 and the like based on the opening completion signal and closing completion signal of the bucket 3 from the pressure switch 18, and drives each operation process of the grab bucket 1. The measurement unit 24 acquires measurement values required for diagnosis from the first to fourth flow meters 13 to 16 and the pressure gauge 17. The timer 25 is used to identify the time of measurement by the first to fourth flow meters 13 to 16 and the pressure gauge 17, and to measure the operation time of the opening operation process OP and the closing operation process CP.

[0030] The measurement unit 24 includes a process start / end detection unit 29 that detects the start and end points of each operation process, a measurement time identification unit 30 that identifies the measurement time for acquiring the necessary measurement values for each operation process of the grab bucket 1, and a measurement value acquisition unit 31 that acquires the measurement values obtained by the first to fourth flow meters 13-16 and the pressure meter 17 at the measurement time in each operation process.

[0031] The measurement unit 24 also includes an operation time measurement unit 32 that measures the operation time of each of the closing operation process CP and the opening operation process OP by counting the elapsed time from the start to the end of each process using a timer 25, and a memory unit 33 that stores the measurement values acquired by the measurement value acquisition unit 31 and the operation time measurement unit 32.

[0032] The diagnosis control unit 22 also includes a diagnosis unit 26 that diagnoses the grab bucket 1 based on the measurement values stored in the storage unit 33, and an output unit 28 that outputs the diagnosis results from the diagnosis unit 26 to a monitor 27.

[0033] Fig. 4 shows how the amount of hydraulic oil in the hydraulic circuit 5 changes in accordance with each operation process when the diagnostic drive unit 23 drives the grab bucket 1. As shown in Fig. 4, the pump discharge amount PM, return flow rate RT, head flow rate HD, rod flow rate RD, and pump pressure PP measured by the first to fourth flow meters and pressure gauge 17 change as shown in Fig. 4 in accordance with the progress of each operation process, namely, the idle circulation process IP, closing operation process CP, closed state maintaining process CM, opening operation process OP, and open state maintaining process OM.

[0034] In FIG. 4, the closing operation process CP after the idle circulation process IP, the closed state maintaining process CM, the subsequent idle circulation process IP, the opening operation process OP, the open state maintaining process OM, and the subsequent idle circulation process IP start sequentially at times T1 to T6, respectively.

[0035] Times T1 and T4 are identified as times when the measurement value of the head flow rate HD by the first flow meter 13 crosses threshold values Th1 and Th2, respectively. Times T2, T3, T5, and T6 are identified as times when the measurement value of the pump pressure PP by the pressure meter 17 crosses threshold value Th3, respectively.

[0036] The operation time measurement unit 32 measures the operation times of the bucket 3 required for the closing operation process CP and the opening operation process OP as the elapsed time from time T1 to time T2 and the elapsed time from time T4 to time T5, respectively. Each measured elapsed time is stored in the memory unit 33 as a measurement value of the operation time OT for each of the closing operation process CP and the opening operation process OP.

[0037] 5 illustrates a method for identifying the measurement time by the measurement time identifying unit 30 for the opening operation process OP. As shown in FIG. 5, the measurement time identifying unit 30 identifies the measurement time by measuring a predetermined time from the start time T4 of the opening operation process OP using the timer 25. This measurement time is a predetermined range of time tw around the time t when the timer 25 measures the predetermined time T.

[0038] The predetermined time T is, for example, a time of 2 seconds or more, such as 3 seconds, taking into consideration the time from the start time T4 of the opening operation process OP until the discharge rate of the hydraulic pump 7 stabilizes. The predetermined range of time tw centered on the time t at which the predetermined time is measured is, for example, a range of time around the time t plus or minus 1 second, or a range of time from the time t to 2 seconds after the time t.

[0039] The measurement unit 24 acquires measurement values of the pump discharge rate PM, return flow rate RT, head flow rate HD, rod flow rate RD, and pump pressure PP for the opening operation process OP within this predetermined range of time tw. Measurement values for the other closing operation process CP, closed state maintenance process CM, and the subsequent idle circulation process IP and open state maintenance process OM are also acquired in a similar manner.

[0040] The measurement value acquisition unit 31 calculates representative values TV such as the average, median, and mode of the measurement values by the first to fourth flow meters 13 to 16 and the pressure meter 17 at multiple points in time during the specified range of time tw, and stores the representative values TV in the memory unit 33 as the measurement values at the time of measurement during the specified range of time tw.

[0041] The diagnostic processing by the diagnostic unit 26 is performed by comparing the measured values of the operating time OT of the closing operation process CP and the opening operation process OP stored in the memory unit 33 in this manner, and the measured values by the first to fourth flow meters 13 to 16 and the pressure meter 17 during measurement in each operation process, with predetermined reference values, upper limit values, and lower limit values for each measured value.

[0042] 6 is a flowchart showing the measurement processing in the measurement unit 24 of the diagnosis control unit 22. This measurement processing is performed while the diagnosis control unit 22 causes the diagnosis drive unit 23 to sequentially drive the grab bucket 1 in accordance with each operation step as shown in FIG.

[0043] That is, when the driving of the grab bucket 1 by the diagnostic driving unit 23 is started, the measurement unit 24 starts the measurement process. When the measurement process is started, as shown in Fig. 6, the measurement unit 24 first detects the arrival of time T1 (see Fig. 4) at which the closing operation process CP starts, using the process start / end detection unit 29 (step S1). When the closing operation process CP starts, the timer 25 starts measuring time (step S2).

[0044] Next, the measurement time identifying unit 30 identifies the measurement time in the closing operation process CP, and at this measurement time, the measurement value acquiring unit 31 acquires the measurement values of the pump discharge rate PM and the pump pressure PP, and the memory unit 33 stores these measurement values in the memory unit 33 (step S3). As described above with reference to Fig. 5, the measurement time is identified as a predetermined range of time tw centered at time t when a predetermined time has elapsed since time T1.

[0045] When the measurement value acquisition unit 31 acquires the measurement values, the hydraulic pump 7 measures the pump discharge rate PM and the pressure gauge 17 measures the pump pressure PP at multiple points during the time tw based on the timing data of the timer 25, and calculates a representative value such as an average value of the measurement values at the multiple points as the measurement values of the pump discharge rate PM and the pump pressure PP in the closing operation process CP. The calculated measurement values are stored in the memory unit 33.

[0046] Next, the process start / end detection unit 29 detects the arrival of time T2 (see FIG. 4) when the closed state maintaining process CM starts (step S4). When time T2 is detected, the operation time measurement unit 32 acquires the operation time of the closing operation process CP and stores it in the memory unit 33 (step S5). This operation time is acquired as the difference between time T2 and time T1 detected in step S1. Next, the timer 25 starts measuring time (step S6).

[0047] Next, the measurement time identifying unit 30 identifies the measurement time in the closed state maintaining process CM, and at this measurement time, the measurement value acquiring unit 31 acquires the measurement values of the pump discharge rate PM, head flow rate HD, rod flow rate RD, return flow rate RT, and pump pressure PP, and these measurement values are stored in the memory unit 33 (step S7). As described above with reference to Fig. 5, the measurement time is identified as a predetermined range of time tw centered on time t, which is a predetermined time after time T1.

[0048] When the measurement value acquisition unit 31 acquires the measurement values, it acquires the measurement values of the pump discharge rate PM, head flow rate HD, rod flow rate RD, return flow rate RT, and pump pressure PP at multiple points during the time tw based on the timing data of the timer 25, and calculates a representative value such as an average value of each measurement value at the multiple points as the value of each measurement value in the closed state maintenance process CM. The calculated measurement values are stored in the memory unit 33.

[0049] Next, the process start / end detection unit 29 detects the time T3 when the closed state maintenance process CM ends, i.e., the idle circulation process IP (see FIG. 4) (step S8). This detection is made as the time when the pump pressure PP detected by the pressure gauge 17 crosses the threshold value Th3. When the time T3 is detected, the timer 25 starts counting (step S9).

[0050] Next, the measurement time identifying unit 30 identifies the measurement time in the idle circulation process IP, and at this measurement time, the measurement value acquiring unit 31 acquires the measurement values of the pump discharge rate PM, head flow rate HD, rod flow rate RD, return flow rate RT, and pump pressure PP, and these measurement values are stored in the memory unit 33 (step S10). The identification of the measurement time and the acquisition of the measurement values are performed in the same manner as in the closed state maintenance process CM.

[0051] Next, the process start / end detection unit 29 detects the arrival of time T4 (see FIG. 4) at which the opening operation process OP starts (step S11).

[0052] When the arrival of time T4 is detected, similarly to steps S2 to S10 described above, the measurement values of the pump discharge rate PM and pump pressure PP in the opening operation process OP are acquired, the operation time OT of the opening operation process OP is acquired, and the measurement values of the pump discharge rate PM, head flow rate HD, rod flow rate RD, return flow rate RT, and pump pressure PP in the open state maintenance process OM and the subsequent idle circulation process IP are acquired and stored in the memory unit 33 (step S12). This completes the measurement process.

[0053] When the measurement process is completed, the diagnosing unit 26 performs a diagnosis process on the grab bucket 1 based on the measurement values stored in the memory unit 33. The result of the diagnosis process is output to the monitor 27 by the output unit 28.

[0054] 7 and 8 show examples of a measurement diagnostic table showing the results of the measurement process by the measurement unit 24 and the results of the diagnostic process by the diagnostic unit 26. In the "process" column of this measurement diagnostic table, items for each of the operation processes in Fig. 4, namely, "closing operation process CP," "closed state maintenance process CM," "idle circulation process IP," "opening operation process OP," "open state maintenance process OM," and "idle circulation process IP," are provided in the numerical order shown in the "No." column.

[0055] The "Measurement specifications" column shows each measurement item (operation time OT, pump protrusion amount PM, etc.) for each operation process shown in the "Process" column. The "Unit" column shows the unit of the measurement value for each measurement item. The "Reference value" column shows the reference value for the measurement value for each measurement item. The "Upper limit value" and "Lower limit value" columns show the upper and lower limit values allowed for the measurement value of each measurement item.

[0056] The "Measurement Value" column shows the first to third measurement results and their average values obtained for each measurement item by the measurement process of FIG. 6 described above in the "1st" to "3rd" and "Average" columns, respectively. The measurement result values for each measurement are obtained by performing the measurement process of FIG. 6 described above once. Note that here, the measurement result values for only the first measurement by the measurement process of FIG. 6 described above are shown.

[0057] In the "Judgment" column, if the value in the "Average" column for each measurement item is between the upper and lower limits and is acceptable, it is indicated with "O", and if it is outside the upper or lower limit and is unacceptable, it is indicated with "X".

[0058] In the "Fault Name" column, for measurement items with an "X" in the "Judgment" column, the columns for the details of the related faults are displayed in the sub-columns. The faults in the columns include "poor pump discharge volume," "internal leak in solenoid valve (energy-saving type)," "internal leak in solenoid valve (fixed / variable type)," "compensator malfunction (energy-saving type)," "poor relief pressure dead head pressure," "internal leak in hydraulic cylinder," and "mechanical malfunction of bucket."

[0059] For measurement items with an "x" in the "Judgment" column, a "■" is displayed in the corresponding defect content column. For each measurement item in the "Measurement Specifications" column, if the "Judgment" column is "x", a "□" is displayed in the corresponding defect content column.

[0060] The storage unit 33 stores diagnostic results indicating more specific details of each fault in association with the "Fault Name" field. For example, if the fault field is "poor pump discharge rate," then "internal leak in hydraulic cylinder" and "internal leak in pump, stuck piston, misaligned settings" are stored in association with this.

[0061] "Internal leak in hydraulic cylinder" is a diagnostic result indicating that there is a malfunction in which the opening process OP or the closing process CP is delayed due to a leak inside the hydraulic cylinder 4. "Internal leak in pump, stuck piston, misalignment in settings" is a diagnostic result indicating that there is a malfunction in which the opening process OP or the closing process CP is delayed due to a leak inside the hydraulic pump 7, a stuck piston in the hydraulic cylinder, or a misalignment in the settings for the discharge volume of the hydraulic pump 7.

[0062] However, "Internal hydraulic cylinder leak" is a diagnostic result that is applied when only the "Poor pump discharge volume" column in the "Operating time" column of the "Measurement specifications" column has a "■" (see Diagnostic example 3-1 below). "Internal pump leak, piston stuck, setting deviation" is a diagnostic result that is applied when the "Poor pump discharge volume" column in both the "Operating time" and "Pump discharge volume" columns of the "Measurement specifications" column has a "■" (see Diagnostic example 3-2 below).

[0063] In this way, the "Judgment" column and the "Fault Name" column for each defect content in the measurement diagnostic table represent the diagnosis results of the grab bucket 1 by the diagnostic unit 26 of the diagnostic control unit 22. The diagnostic control unit 22 displays the measurement diagnostic table representing these diagnostic results on the monitor 27 by the output unit 28.

[0064] The storage unit 33 stores data in each column of the measurement diagnosis table as one record for each measurement item, in association with each measurement item ("operating time," "pump discharge volume," etc.) in the "measurement specifications" column of the measurement diagnosis tables in Figures 7 and 8. Furthermore, the storage unit 33 stores diagnostic results indicating more specific details of the malfunction, in association with each column of the "fault name" details of the malfunction ("poor pump discharge volume," "internal leakage in solenoid valve (energy saving type)," etc.) as described above.

[0065] Therefore, based on the record of the diagnostic result indicating the defect content, a more specific diagnostic result corresponding to the defect content column where "■" is displayed is displayed. Therefore, when "■" is displayed in the measurement diagnostic table displayed on the monitor 27, it means that a diagnosis has been made that there is a defect in the diagnostic result associated with the corresponding defect content column.

[0066] The diagnostic control unit 22 can be configured so that the contents of such diagnostic results can be displayed and confirmed on the monitor 27, for example, by indicating the "■" mark in the measurement diagnostic table displayed on the monitor 27, or by specifying the column name of the corresponding defect content column.

[0067] In order to obtain such a diagnostic result, the diagnostic unit 26 of the diagnostic control unit 22 performs the following diagnostic processing based on each measurement value (data corresponding to the value in the "measurement value" column of the measurement diagnostic table) acquired in the measurement processing of Figure 6 and stored in the memory unit 33.

[0068] 9 shows an example of the diagnostic process by the diagnostic unit 26. When the process starts, the first record stored in the storage unit 33 in a format corresponding to the measurement diagnostic table in FIGS. 7 and 8, that is, the record of the "operation time" in the "opening operation process", is read out (step S51).

[0069] Then, for the read record, it is determined whether the value X in the "Average" column is within the range of the "Upper Limit Value" and the "Lower Limit Value" (step S52). As a result of this determination, if it is determined that it is within the range (Lower Limit Value ≤ X ≤ Upper Limit Value), an "〇" is recorded in the "Judgment" column (step S53), and the process proceeds to step S57.

[0070] If it is determined in step S52 that it is outside the range (X < Lower Limit Value or Upper Limit Value < X), an "×" is recorded in the "Judgment" column (step S54). Also, a "■" is recorded in the column of the defect content in the "Defect Name" column corresponding to the measurement item in the "Measurement Specification" column of the record (step S55), and the defect count variable N for that defect content is incremented (step S56). Note that as the defect count variable N, N1 to N7 are set in order for the defect content columns of seven types of "Defect Name".

[0071] Specifically, if the read record is the first record, since the measurement item in the "Measurement Specification" column is "Operation Time", a "■" is recorded in the column of "Pump Discharge Amount Defect" corresponding to "Operation Time" in the "Defect Name" column, and the defect count variable N1 corresponding to this column is incremented.

[0072] Next, it is determined whether the record is the last record (step S57). If it is determined that it is not the last record, the next record is read (step S58), and the process returns to step S52, and the processing from step S52 to step S57 is repeated. If it is determined that it is the last record, according to the values of the defect count variables N1 to N7 for each of the seven types of defect contents of the "Defect Name", the color of the column name of the defect content is set (step S59), and the diagnosis process is terminated.

[0073] The setting of the color of the column name of the defect content is performed, for example, by setting the color of the column name of the defect content where the defect count variable N is 1 to orange and the color of the column name of the defect content where the defect count variable N is 2 or more to red.

[0074] For example, when data such as those shown in the measurement diagnosis tables of Fig. 7 and Fig. 8 are obtained, the column name of the defect content "poor pump discharge volume" is set to red (shown in a slightly dark solid color in Fig. 7 and Fig. 8) because the defect count variable N1 is 4. Also, the column name of the defect content "internal leakage of solenoid valve (energy saving type)" is set to orange (shown in a light solid color in Fig. 7 and Fig. 8) because the defect count variable N2 is 1.

[0075] The output unit 28 of the diagnosis control unit 22 can output to the monitor, as the diagnosis results of the grab bucket 1, the measurement and diagnosis results of the measurement unit 24 and the diagnosis unit 26, tables such as those shown in the measurement diagnosis tables of Figures 7 and 8.

[0076] The following specific examples can be given as diagnostic results obtained by the grab bucket diagnostic device 21 as shown in the above measurement diagnostic table.

[0077] (Diagnosis result 1): During the opening operation process OP, if the average of the measured values of the pump discharge rate PM by the third flow meter 15 falls below the lower limit of 21.6 [L / min], an "x" is displayed in the "Judgment" column, and a "■" is displayed in the "Fault name" column of "Faulty pump discharge rate." In this case, based on the data of more specific malfunction details stored in the memory unit 33 in association with the "Faulty pump discharge rate" column, a diagnosis result is obtained that there is an internal leak in the hydraulic pump 7, a sticking of the piston of the hydraulic pump 7, or a deviation in the setting of the discharge rate of the hydraulic pump 7.

[0078] (Diagnosis result 2): For the closed state maintenance process CM, if the average measured value of the pump pressure PP by the pressure gauge 17 is less than the lower limit value of 19.5 [L / min], an "x" is displayed in the "Judgment" column, and a "■" is displayed in the "Relief pressure dead head pressure failure" column of the "Fault name". In this case, similarly, based on the data in the memory unit 33, a diagnosis result is obtained that there is a malfunction due to a drop in the dead head pressure of the hydraulic pump 7 and a deviation in the relief pressure.

[0079] (Diagnosis result 3): For the opening operation process OP or the closing operation process CP, if the average of the measured values of the pump discharge rate PM by the third flow meter 15 is between the upper and lower limit values and the measured value of the operation time exceeds the upper limit value, "◯" is displayed in the "Judgment" column for the pump discharge rate PM and "X" is displayed in the "Judgment" column for the operation time. Also, "■" is displayed in the "Internal leak in hydraulic cylinder" column of the "Fault name" for the operation time. In this case, similarly, based on the data in the memory unit 33, a diagnosis result is obtained that there is a malfunction in which the opening operation process OP or the closing operation process CP is delayed due to a leak inside the hydraulic cylinder 4.

[0080] (Diagnosis result 4): For the opening operation process OP or the closing operation process CP, if the measured value of the pump discharge rate PM by the third flow meter 15 is less than the lower limit and the measured value of the operating time exceeds the upper limit, an "x" is displayed in the "Judgment" column for the pump discharge rate PM and the operating time, and a "■" is displayed in the "Fault name" column for "Faulty pump discharge rate." In this case, similarly, based on the data in the memory unit 33, a diagnosis result is obtained that there is a malfunction in which the opening operation process OP or the closing operation process CP is delayed due to a leak inside the hydraulic pump 7, a stuck piston in the hydraulic cylinder 4, or a deviation in the setting of the pump discharge rate PM of the hydraulic pump 7.

[0081] (Diagnosis result 5): When the measurement value of the pump discharge rate PM by the third flow meter 15 exceeds the upper limit or is less than the lower limit for the open state maintenance process OM, the closed state maintenance process CM, or the idle circulation process IP, an "x" is displayed in the "Determination" column for the pump discharge rate PM, and a "■" is displayed in the "Fault name" columns for "Internal leak in solenoid valve (energy saving type)," "Internal leak in solenoid valve (fixed / variable type)," and "Internal leak in hydraulic cylinder." In this case, similarly, based on the data in the memory unit 33, a diagnosis result is obtained that there is a leak in the solenoid valve or a leak in the hydraulic cylinder 4.

[0082] (Diagnosis result 6): For the open state maintaining process OM or the closed state maintaining process CM, if the return flow rate RT measured by the fourth flow meter 16 exceeds the upper limit or is less than the lower limit, an "x" is displayed in the "Determination" column for the return flow rate, and a "■" is displayed in the "Solenoid valve internal leak (energy saving type)" column of the "Fault name." In this case, similarly, based on the data in the memory unit 33, a diagnosis result is obtained that there is a leak inside the directional control valve 9.

[0083] (Diagnosis result 7): For the open state maintaining process OM or the closed state maintaining process CM, if the measurement value of the head flow rate HD or the rod flow rate RD by the first flow meter 13 or the second flow meter 14 exceeds the upper limit value or is below the lower limit value, an "x" is displayed in the "Determination" column for the head flow rate or the rod flow rate, and a "■" is displayed in the "Internal leak in solenoid valve (energy saving type)" and "Internal leak in hydraulic cylinder" columns of the "Fault name". In this case, similarly, based on the data in the memory unit 33, a diagnosis result is obtained that there is a leak inside the directional control valve 9 or the hydraulic cylinder 4.

[0084] (Diagnosis result 8): For the opening operation process OP or the closing operation process CP, if the measurement value of the pump pressure PP measured by the pressure gauge 17 exceeds the upper limit, an "x" is displayed in the "Judgment" column, and a "■" is displayed in the "Fault name" column for "Relief pressure dead head pressure failure." In this case, similarly, based on the data in the memory unit 33, a diagnosis result is obtained that the bucket 3 has been galled or that the hydraulic pump 7 has failed.

[0085] (Diagnosis result 9): For the idle circulation process IP, if the measurement value of the return flow rate RT by the fourth flow meter exceeds the upper limit, an "x" is displayed in the "Judgment" column, and a "■" is displayed in the "Compensator malfunction (energy saving type)" column under "Fault name." In this case, similarly, based on the data in the memory unit 33, a diagnosis result is obtained that the hydraulic compensator is faulty.

[0086] As described above, according to this embodiment, it is possible to specifically and accurately diagnose what kind of malfunction exists in which part of the grab bucket 1 based on the operating times in the closing operation process CP and the opening operation process OP, the measured values of the pump discharge volume PM and the pump pressure PP, and further the measured values of the pump discharge volume PM, head flow rate HD, rod flow rate RD, return flow rate RT and pump pressure PP in the closed state maintenance process CM, the open state maintenance process OM and the idle circulation process IP.

[0087] Furthermore, since the measurement time for each operation step is specified by the elapsed time from the start of the operation step, which is determined for each operation step, the measurement can be performed at the optimal time for each operation step, thereby improving the accuracy of the diagnosis.

[0088] In addition, a certain range of time is set as the measurement time for each operating process, and representative values such as the average, median, and mode of the measurement values at multiple points in that range of time are used as the measurement values used for diagnosis, thereby further improving the accuracy of diagnosis.

[0089] Furthermore, the diagnosis of the grab bucket 1 can be performed objectively by comparing the measurement values obtained for each process with predetermined reference values, upper limit values, and lower limit values.

[0090] Furthermore, based on the measurement value for each measurement specification (measurement content) of each operation process, the defect content corresponding to the comparison result with the reference value, upper limit value, and lower limit value is set in advance in the storage unit 33, so the defect content can be easily identified and the diagnosis result can be obtained. This makes it possible to automate the diagnosis.

[0091] Although the embodiments of the present invention have been described above, the present invention is not limited to this. For example, the number of times measurement values are acquired for each measurement item in the "Measurement Specifications" column for each process is not limited to three, but may be two, four, or more. Furthermore, instead of one hydraulic cylinder, two or more flow meters may be installed on the head and rod sides of all hydraulic cylinders of the grab bucket, and diagnosis may be performed by referring to these measurement values. Furthermore, the grab bucket may be a poly-type grab or a fork-type grab.

[0092] Furthermore, in the diagnosis control unit 22, after the measurement unit 24 has completed acquiring all measurement values related to all operation processes, the diagnosis unit 26 performs diagnostic processing and displays the diagnostic results. Alternatively, measurement values and diagnostic results may be acquired for each operation process or each measurement item, and the results may be displayed.

[0093] Furthermore, in the diagnosis control unit 22, the diagnosis drive unit 23 automatically performs a series of operation steps as shown in FIG. 4 while the measurement unit 24 performs measurements. Alternatively, the grab bucket may be operated for each desired operation step based on instructions from an operator, and measurement values may be acquired and diagnosed for each operation step. [Explanation of symbols]

[0094] 1...grab bucket, 2...grab, 3...bucket, 4...hydraulic cylinder, 5...hydraulic circuit, 6...oil tank, 7...hydraulic pump, 8...motor, 9...directional switching valve, 10a to 10h, 10b1 to 10b3, 10c1, 10c2, 10e1 to 10e3, 10f1, 10f2...oil flow path, 11...first branch point, 12...second branch point, 13 to 16...first to fourth flow meters, 17...pressure gauge, 18...pressure switch, 19...filter, 20...variable throttle valve, 21...grab bucket diagnostic device, 22...diagnosis control unit, 23...diagnosis drive unit, 24...measurement unit, 25...timer, 26...diagnosis unit, 27...monitor, 28...output unit, 29...process start / end detection unit, 30...measurement time identification unit, 31...measurement value acquisition unit, 32...operation time measurement unit, 33...storage unit.

Claims

1. A grab bucket diagnostic device that presents a diagnostic result indicating whether or not there is a malfunction in a grab bucket that has a plurality of buckets driven by hydraulic cylinders that are operated by hydraulic oil discharged from an oil tank by a hydraulic pump, and that operates through each of the operation steps of an opening operation step for opening the buckets, an open state maintaining step for maintaining the buckets in an open state, a closing operation step for closing the buckets, a closed state maintaining step for maintaining the buckets in a closed state, and an idle circulation step in which hydraulic oil is not substantially supplied to the hydraulic cylinders, a first, second, third or fourth flow meter that measures the flow rate of hydraulic oil flowing in and out of the head side or rod side of the hydraulic cylinder, the flow rate of hydraulic oil discharged by the hydraulic pump, or the flow rate of hydraulic oil returning to the oil tank, or a pressure meter that measures the oil pressure of the hydraulic oil discharged by the hydraulic pump; a timer for identifying the time of measurement by the first, second, third or fourth flow meter or the pressure meter; a measurement time specifying unit that specifies the measurement time for each of one or more operation steps by measuring a predetermined time from a start point of the operation step, the predetermined time being determined for each operation step, using the timer; a diagnostic unit that presents the diagnostic result based on a measurement value by the first, second, third or fourth flow meter or the pressure meter at the time of measurement in the operation process for which the time of measurement has been specified.

2. an operation time measurement unit that measures an operation time of the bucket required for the closing operation process or the opening operation process by measuring an elapsed time from a start point to an end point of the closing operation process or the opening operation process with a timer, 2. The grab bucket diagnostic device according to claim 1, wherein the diagnostic unit presents the diagnostic result based on a measurement value by the first, second, third or fourth flow meter or the pressure meter or a measurement value by the operation time measurement unit.

3. the measurement time of the first, second, third or fourth flow meter or the pressure meter is a predetermined range of time around the time point at which the timer measures the predetermined time, The grab bucket diagnostic device according to claim 1, wherein the measurement value is a representative value such as an average value of measurement values obtained by the first, second, third, or fourth flow meter or the pressure meter at a plurality of points in time within the predetermined time range.

4. 3. The grab bucket diagnostic device according to claim 1 or 2, wherein the presentation of the diagnostic result is performed by comparing each measurement value with a reference value or an upper limit value and a lower limit value that are predetermined for each measurement value.

5. 5. The grab bucket diagnostic device according to claim 4, wherein, when the measurement value of the third flow meter during the opening operation process is less than the lower limit value, the diagnostic unit presents a diagnostic result indicating that there is a malfunction due to an internal leak of the hydraulic pump, sticking of a piston of the hydraulic pump, or a deviation in a setting for the discharge amount of the hydraulic pump.

6. 5. The grab bucket diagnostic device according to claim 4, wherein, when the measurement value by the pressure gauge is less than the lower limit value during the open state maintaining process or the closed state maintaining process, the diagnostic unit presents a diagnostic result indicating that there is a malfunction due to a decrease in dead head pressure of the hydraulic pump and a deviation in relief pressure.

7. 5. The grab bucket diagnostic device according to claim 4, wherein, when the measurement value by the third flow meter is a value between the upper limit value and the lower limit value and the measurement value by the operation time measurement unit exceeds the upper limit value, the diagnostic unit presents a diagnostic result indicating that there is a malfunction in which the opening operation process or the closing operation process is delayed due to a leak inside the hydraulic cylinder.

8. 5. The grab bucket diagnostic device according to claim 4, wherein, when the measurement value by the third flow meter is less than the lower limit value and the measurement value by the operation time measurement unit exceeds the upper limit value with respect to the opening operation process or the closing operation process, the diagnostic unit presents a diagnostic result indicating that there is a malfunction in which the opening operation process or the closing operation process is delayed due to a leak inside the hydraulic pump, sticking of the piston of the hydraulic cylinder, or a deviation in setting for the discharge amount of the hydraulic pump.

9. 5. The grab bucket diagnostic device according to claim 4, wherein the diagnostic unit presents a diagnostic result indicating that there is a leak inside a solenoid valve that controls a supply path of hydraulic oil from the hydraulic pump or a leak inside the hydraulic cylinder, when the measurement value of the third flow meter exceeds the upper limit value in the open state maintaining process, the closed state maintaining process, or the idle circulation process.

10. 5. The grab bucket diagnostic device according to claim 4, wherein the diagnostic unit presents a diagnostic result indicating that there is a leak inside a solenoid valve that controls a supply path of hydraulic oil from the hydraulic pump, when the measurement value by the fourth flow meter exceeds the upper limit value or is less than the lower limit value during the open state maintaining process or the closed state maintaining process.

11. 5. The grab bucket diagnostic device according to claim 4, wherein the diagnostic unit presents a diagnostic result indicating that there is a leak inside the hydraulic cylinder when the measurement value by the first or second flow meter exceeds the upper limit value during the open state maintaining process or the closed state maintaining process.

12. 5. The grab bucket diagnostic device according to claim 4, wherein the diagnostic unit presents a diagnostic result that the bucket has been seized or that the hydraulic pump has failed, when the measurement value by the pressure gauge exceeds the upper limit value during the opening operation process or the closing operation process.

13. The grab bucket diagnostic device according to claim 4, wherein the diagnostic unit presents a diagnostic result indicating that the hydraulic compensator has failed when the measurement value of the fourth flow meter exceeds the upper limit value in the idle circulation process.

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