Engine diagnosis device

Abstract

To provide an engine diagnosis device that can more easily and accurately diagnose the startability of a work machine engine.SOLUTION: An engine diagnosis device determines, in a histogram of engine start time T1, the quality of engine startability based on the difference DT13, DT12, DT23 in start time T1 between any two characteristic points among: a first characteristic point SP1 that is the boundary where the frequency of start time T1 changes from increasing to decreasing; a second characteristic point SP2 that is the boundary where the frequency of start time T1 changes from decreasing to increasing; and a third characteristic point SP3 that is longer than the start time T1 at the second characteristic point SP2 and is the boundary where the frequency of start time T1 changes from increasing to decreasing.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to an engine diagnostic device. [Background technology]

[0002] Conventionally, there has been known an invention relating to an engine diagnostic device for construction machinery that diagnoses the starting performance of an engine used in construction machinery (see Patent Document 1 below). The conventional engine diagnostic device described in Patent Document 1 includes a calculation unit and a diagnosis unit. The calculation unit calculates the time required for the engine speed to reach a preset threshold based on the engine speed measured by a speed sensor that measures the engine speed. The diagnosis unit diagnoses the engine starting performance by comparing the time calculated by the calculation unit with a preset reference value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-68776 A Summary of the Invention [Problem to be solved by the invention]

[0004] The calculation unit of the engine diagnosis device of the above-mentioned Patent Document 1 obtains the time t1 from engine start to engine speed reaching the first threshold value by extrapolation processing using point P1 where the engine speed is lower than the first threshold value and point P2 where the engine speed is higher than the first threshold value (see Patent Document 1, paragraph 0043, FIG. 8, etc.). This is because time errors may occur in the speed data collected at each sampling time due to data transfer delays, etc.

[0005] However, if a data transfer delay occurs at an engine speed near the first threshold, the difference in engine speed between point P1 and point P2 decreases, and the error in the engine start point P0 obtained by the extrapolation process may increase. If the error in the engine start point P0 increases, an outlier in the start time data occurs, which is a start time that is significantly different from the actual time from when the engine starts until the engine speed reaches a predetermined speed.

[0006] In order to exclude such outliers in the start time data caused by the delay in the transfer of the engine speed data from the time series distribution of the start time data, it is conceivable to set a threshold value for the start time. However, since the threshold value for the start time is set based on the time series distribution of the start time data, there is a problem in performing an engine startability diagnosis more easily and accurately.

[0007] The present disclosure provides an engine diagnostic device that can more easily and accurately diagnose the startability of a work machine engine. [Means for solving the problem]

[0008] One aspect of the present disclosure is an engine diagnosis device that diagnoses the startability of an engine for a work machine having a hydraulic pump, an engine that rotates the hydraulic pump, and a rotation speed detection device that detects the rotation speed of the engine, the engine diagnosis device comprising: a history data recording unit that calculates a start time from when the engine is started until the engine rotation speed reaches a predetermined rotation speed based on the engine rotation speed obtained from the rotation speed detection device, and records the calculated start time as history data; a histogram generation unit that generates a histogram of the start time based on the history data recorded by the history data recording unit; and a startability judgment unit that judges whether the startability of the engine is good or bad based on the difference in start time between any two of the following feature points in the histogram generated by the histogram generation unit: a first feature point that is a boundary where the frequency of the start time turns from an increase to a decrease, a second feature point that is a boundary where the frequency of the start time turns from a decrease to an increase, and a third feature point that is longer than the start time at the second feature point and is a boundary where the frequency of the start time turns from an increase to a decrease. Effect of the Invention

[0009] According to the above aspect of the present disclosure, it is possible to provide an engine diagnosis device that can more easily and accurately diagnose the startability of an engine of a work machine. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram of a work machine illustrating an embodiment of an engine diagnosis device according to the present disclosure. [Diagram 2] FIG. 2 is a functional block diagram of an engine diagnostic device mounted on the work machine of FIG. 1 . [Diagram 3] 3 is a flow diagram illustrating an example of the operation of the engine diagnosis device of FIG. 2. [Figure 4] FIG. 4 is a flow diagram illustrating the details of the data collection of FIG. 3. [Diagram 5] FIG. 4 is a flow diagram illustrating the details of the data processing of FIG. 3. [Figure 6] An example of a histogram of engine start times generated by evaluating the data in Figure 3. [Figure 7] FIG. 4 is a flow diagram for explaining details of the data evaluation in FIG. 3 (first embodiment). [Figure 8] FIG. 4 is a flow chart for explaining details of the startability diagnosis in FIG. 3 . [Figure 9] FIG. 4 is a flow diagram for explaining details of the data evaluation in FIG. 3 (second embodiment). [Figure 10] FIG. 4 is a flow diagram for explaining details of the data evaluation in FIG. 3 (third embodiment). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of an engine diagnosis device according to the present disclosure will be described with reference to the drawings.

[0012] Fig. 1 is a block diagram of a work machine showing one embodiment of an engine diagnosis device according to the present disclosure. In Fig. 1, the transmission of power is indicated by a thick arrow, the output of electric power or a signal is indicated by a thin solid arrow, and the supply of fuel is indicated by a dashed dotted arrow. The engine diagnosis device 200 of this embodiment is a device that diagnoses the quality of startability of an engine 102 mounted on a work machine 100.

[0013] The diagnosis target of the engine diagnosis device 200 is, for example, a work machine 100 having a hydraulic pump 101, an engine 102 that rotates the hydraulic pump 101, and a rotation speed detection device 111 that detects the rotation speed of the engine 102. More specifically, the work machine 100 that is the diagnosis target of the engine diagnosis device 200 of this embodiment is, for example, a construction machine such as a hydraulic excavator, a wheel loader, or a dump truck.

[0014] The engine diagnostic device 200 can be configured, for example, by a control device 120 mounted on the work machine 100. In addition, the engine diagnostic device 200 may be configured, for example, by a computer external to the work machine 100 that is provided so as to be able to communicate with the control device 120 of the work machine 100.

[0015] The work machine 100 is equipped with, for example, the above-mentioned hydraulic pump 101, engine 102, rotation speed detection device 111, and control device 120, as well as an alternator 103, a battery 104, a starter 105, a fuel pump 106, and multiple detection devices 110. The hydraulic pump 101 is, for example, a swash plate type variable displacement piston pump, and is mechanically connected to the output shaft of the engine 102, and supplies hydraulic oil to the hydraulic device of the work machine 100. The engine 102 is, for example, a four-cylinder internal combustion engine, and is a power source that rotates the hydraulic pump 101 and also rotates the alternator 103.

[0016] The rotation speed detection device 111 detects the rotation speed of the engine 102 and outputs a signal corresponding to the rotation speed of the engine 102 to the control device 120. The control device 120 is an electronic control device constituted by one or more microcontrollers including, for example, a processing device 121 such as a CPU, a storage device 122 such as a RAM or ROM, a timer, and an input / output unit. The control device 120 outputs a control signal to the engine 102, for example, to control the fuel injection amount and ignition timing.

[0017] Alternator 103 is rotated, for example, by the power of engine 102 to generate electricity and supplies the generated electricity to battery 104. Battery 104 is charged, for example, by the electricity supplied from alternator 103 and supplies electricity to starter 105, fuel pump 106, rotation speed detection device 111, and a plurality of other detection devices 110. Starter 105 is rotated, for example, by the electricity supplied from battery 104 to start engine 102. Fuel pump 106 is driven, for example, by the electricity supplied from battery 104 to supply fuel to engine 102.

[0018] The multiple detection devices 110 include, for example, in addition to the above-mentioned rotation speed detection device 111, a torque detection device 112, a fuel flow rate detection device 113, an oil temperature detection device 114, a tilt angle detection device 115, and a voltage value detection device 116. These detection devices 110 respectively detect the torque of the engine 102, the flow rate of fuel supplied by the fuel pump 106, the temperature of the hydraulic oil supplied by the hydraulic pump 101, the tilt angle of the swash plate of the hydraulic pump 101, and the voltage of the battery 104 at the time of engine start-up, and output signals according to these detection values ​​to the control device 120.

[0019] Fig. 2 is a functional block diagram of an engine diagnostic device 200 mounted on the work machine 100 of Fig. 1. As described above, the engine diagnostic device 200 of this embodiment is configured, for example, by the control device 120 mounted on the work machine 100, and has a history data recording unit 201, a histogram generating unit 202, and a startability determining unit 203. These units of the engine diagnostic device 200 represent the functions of the engine diagnostic device 200 that are realized, for example, by the processing unit 121 executing a program stored in the storage device 122. The engine diagnostic device 200 may be connected, for example, to a monitor 107 such as a liquid crystal display device installed in the driver's cab of the work machine 100.

[0020] An example of the operation of the engine diagnosis device 200 of this embodiment will be described below. Fig. 3 is a flow diagram illustrating an example of the operation of the engine diagnosis device 200. When the process flow of Fig. 3 is started, the engine diagnosis device 200 executes a process P1 in which the history data recording unit 201 acquires the key position signal KP and the engine state signal ES, for example.

[0021] The key position signal KP is switched to a signal representing any integer from 0 to 3, for example, by key operation by the operator of the work machine 100. More specifically, for example, 0, 1, 2, and 3 of the key position signal KP correspond to the key positions "OFF," "accessory state," "ON," and "engine start (cranking)," respectively. 0 and 1 of the engine state signal ES correspond to the "engine stopped state" and "engine running state," respectively.

[0022] Next, the history data recording unit 201 executes, for example, an engine start determination process P2. In this process P2, if the history data recording unit 201 determines that, for example, the key position signal KP acquired in the previous process P1 is less than 2 or the engine state signal ES is 1 (NO), it executes the processes P1 and P2 repeatedly at a predetermined cycle. Also, if the history data recording unit 201 determines, for example, in the process P2 that the key position signal KP is 2 or more and the engine state signal ES is 0 (YES), it executes data collection P3.

[0023] In this case, the key position operated by the operator of the work machine 100 is set to "ON." Therefore, power is supplied from the battery 104 to the multiple detection devices 110 including the rotation speed detection device 111, and the multiple detection devices 110 start detecting start-related data including the rotation speed of the engine 102 and recording the data in the storage device 122.

[0024] Fig. 4 is a flow diagram showing details of data collection P3 shown in Fig. 3. For example, when the history data recording unit 201 starts data collection P3 shown in Fig. 4, it first executes process P31 for collecting start-related data. In this process P31, the history data recording unit 201 sets, for example, a parameter n for data counting to an initial value of zero (n=0).

[0025] Furthermore, the history data recording unit 201 starts counting at a predetermined cycle based on, for example, a fixed cycle clock. The history data recording unit 201 also acquires start-up related data including the fuel flow rate, the hydraulic oil temperature, and the tilt angle of the swash plate of the hydraulic pump 101 detected by the fuel flow rate detection device 113, the oil temperature detection device 114, and the tilt angle detection device 115 in synchronization with the counting. Furthermore, the history data recording unit 201 adds 1 to a parameter n for counting data (n=n+1) every time it acquires start-up related data. For example, the history data recording unit 201 groups the acquired start-up related data together with the parameter n and stores the group in the storage device 122.

[0026] Next, the history data recording unit 201 executes, for example, a start determination process P32. In this process P32, the history data recording unit 201 acquires, for example, a key position signal KP and an engine state signal ES, and determines whether KP=3 and ES=1 are satisfied. If the history data recording unit 201 determines that KP=3 and ES=1 are not satisfied (NO), it repeatedly executes the process P32. If the history data recording unit 201 determines that KP=3 and ES=1 are satisfied (YES), that is, if the key position is engine start and the engine 102 is in an engine start (cranking) state, it executes a fuel supply determination process P33.

[0027] In this process P33, the history data recording unit 201 determines, for example, whether or not the fuel flow rate FF acquired from the fuel flow rate detection device 113 is greater than zero. If the history data recording unit 201 determines that the fuel flow rate FF is zero (NO), it repeatedly executes the process P33. If the history data recording unit 201 determines that the fuel flow rate FF is greater than zero (YES), it executes a process P34 in which the engine speed of the engine 102 acquired from the engine speed detection device 111 is set to the initial explosion speed f(x).

[0028] Next, the history data recording unit 201 executes a process P35 for determining whether or not the current engine 102 revolution speed f(n) acquired from the revolution speed detection device 111 is greater than the initial combustion revolution speed f(x). If the revolution speed f(n) is equal to or less than the initial combustion revolution speed f(x) (NO), the history data recording unit 201 repeats the process P35. If the revolution speed f(n) is greater than the initial combustion revolution speed f(x) (YES), the history data recording unit 201 executes an idling revolution determination process P36.

[0029] In this process P36, if the history data recording unit 201 determines that the current engine 102 revolutions f(n) acquired from the revolutions detection device 111 is greater than the previously acquired revolutions f(n-1) (NO), the history data recording unit 201 repeats processes P34 to P36. Also, if the history data recording unit 201 determines that the current engine 102 revolutions f(n) acquired from the revolutions detection device 111 is equal to or less than the previously acquired revolutions f(n-1) (YES), that is, if the current engine 102 revolutions f(n) has reached the idle revolutions, the history data recording unit 201 executes the next process P37.

[0030] In this process P37, the history data recording unit 201 deletes, for example, the revolution speed data of the engine 102 from the revolution speed f(n+1) that is later than the revolution speed f(n) at which the idle revolution speed is reached. After that, the engine diagnosis device 200 ends the data collection P3 shown in Figures 3 and 4, and executes the data process P4 shown in Figure 3.

[0031] Fig. 5 is a flow diagram for explaining details of the data processing P4 shown in Fig. 3. Note that the data processing P4 in this embodiment is similar to the data processing described in paragraphs 0039 to 0046, Fig. 7 and Fig. 8 of the above-mentioned Patent Document 1, and therefore the explanation will be omitted as appropriate.

[0032] For example, when starting data process P4 shown in Fig. 5, the history data recording unit 201 first executes process P401 to acquire the tilt angle of the hydraulic pump 101. In this process P401, the history data recording unit 201 acquires, for example, the tilt angle of the swash plate of the hydraulic pump 101 detected by the tilt angle detection device 115 and recorded in the storage device 122. Thereafter, the history data recording unit 201 executes, for example, processes P402 to P405 of Fig. 5.

[0033] As a result, the history data recording unit 201 can calculate the delay time of the starting characteristics of the engine 102 caused by the influence of the hydraulic oil filled in the hydraulic pump 101, for example, based on the tilt angle of the swash plate of the hydraulic pump 101 acquired in process P401. Also, based on the calculated delay time, the history data recording unit 201 can simulate the starting characteristics of the engine 102 alone, excluding the delay in the rise of the rotation speed of the engine 102 caused by the influence of the viscous resistance of the hydraulic oil.

[0034] 5. In addition, the history data recording unit 201 executes, for example, process P406 to process P410. This allows the history data recording unit 201 to calculate, for example, a time t1 from when the engine 102 is started until the engine speed reaches a first threshold value, and a time t2 from the first threshold value until the engine speed reaches a second threshold value. The first threshold value is set, for example, to a speed that is 75% or more and 90% or less of the initial explosion speed, and the second threshold value is set, for example, to a speed that is 75% or more and 90% or less of the idle speed.

[0035] Furthermore, the history data recording unit 201 can calculate the start time T1 required for the engine 102 speed to reach the initial explosion speed from zero and the time T2 required for the engine 102 speed to reach the idle speed from the initial explosion speed, for example, by extrapolation using the time t1 and the time t2. After that, the history data recording unit 201 executes a process P411 for storing the times T1 and T2 calculated in the processes P409 and P410 in the storage device 122, and ends the data process P4 shown in Figures 3 and 5. After that, the engine diagnosis device 200 executes the data evaluation P5 shown in Figure 3 based on the data processed in the data process P4, and judges whether the startability of the engine 102 is good or bad.

[0036] 6 is an example of a histogram of the start time T1 generated by the histogram generating unit 202. In the data evaluation P5, the histogram generating unit 202 generates a histogram of the start time T1 based on the history data of the start time T1 recorded by the history data recording unit 201. In addition, the startability determining unit 203 determines the quality of the startability of the engine 102 based on the differences DT13, DT12, and DT23 in the start time T1 between any two of the first feature point SP1, the second feature point SP2, and the third feature point SP3 in the histogram of the start time T1 generated by the histogram generating unit 202.

[0037] The first feature point SP1 is, for example, the start time T1 at which the frequency of the start time T1 becomes a boundary where the frequency of the start time T1 changes from a first increase to a decrease in the histogram generated by the histogram generating unit 202, and is the start time T1 at which the frequency reaches its first peak. The second feature point SP2 is, for example, the start time T1 at which the frequency of the start time T1 changes from a first decrease to an increase, and is the start time T1 at which the frequency reaches its first bottom. The third feature point SP3 is longer than the start time T1 at the second feature point SP2, and is the start time T1 at which the frequency of the start time T1 changes from a second increase to a decrease, and is the start time T1 at which the frequency reaches its second peak.

[0038] Fig. 7 is a flow diagram showing details of a first embodiment using the first feature point SP1 and the third feature point SP3 in the data evaluation P5 of Fig. 3. When the engine diagnosis device 200 starts the data evaluation P5 shown in Fig. 7, it executes a process P501 for acquiring history data of the start time T1 previously stored in the storage device 122 by the history data recording unit 201, and a process P502 for generating a histogram of the start time T1.

[0039] For example, in process P501, the histogram generating unit 202 acquires from the storage device 122 past history data of the start time T1 from when the engine speed is zero until it reaches the initial explosion speed, and generates a histogram of the start time T1 in process P502. For example, in process P502, the histogram generating unit 202 calculates the frequency of accumulating the number of history data of the start time T1 acquired in the previous process P501 for each predetermined class width, thereby generating a histogram of the start time T1 from when the engine speed of the engine 102 is zero until it reaches the initial explosion speed, as shown in Fig. 6.

[0040] Next, the startability determination unit 203 executes a process P503 in which it assigns numbers to each class in the histogram of the start time T1 in ascending order of the start time T1, and a process P504 in which it sets a parameter n for counting classes to zero. Furthermore, the startability determination unit 203 executes a process P505 in which it defines the frequency of the nth class in the histogram of the start time T1 as fr(n) and adds 1 to the parameter n.

[0041] Next, the startability determination unit 203 executes process P506 to determine whether the frequency fr(n) of the nth class of the histogram of the start time T1 is equal to or less than the frequency fr(n+1) of the n+1th class. If the startability determination unit 203 determines that the frequency continues to increase and that the condition is satisfied in process P506 (YES), it repeats processes P505 and P506, thereby incrementing the parameter n by 1.

[0042] On the other hand, when the frequency has changed from an increase to a decrease and it is determined in process P506 that the condition is no longer satisfied (NO), the startability determination unit 203 executes process P507 to record a first characteristic point SP1 in the storage device 122. Here, the startability determination unit 203 records, for example, the minimum, average, median or maximum value of the start time T1 in the class number corresponding to the parameter n when the condition in process P506 is no longer satisfied, as the first characteristic point SP1 in the storage device 122. This first characteristic point SP1 corresponds, for example, to the first peak in the histogram in FIG. 6.

[0043] Thereafter, the startability determination unit 203 executes process P508 to add 1 to parameter n, and process P509 to determine whether the frequency fr(n) of the nth class of the histogram of start time T1 is equal to or greater than the frequency fr(n+1) of the n+1th class. If the startability determination unit 203 determines that the frequency continues to decrease and that the condition is satisfied (YES) in process P509, it repeats processes P508 and P509 to increment the parameter n by 1.

[0044] Furthermore, when the startability determination unit 203 determines in process P509 that the frequency has changed from a decrease to an increase and that the condition is no longer satisfied (NO), it executes process P510 to add 1 to parameter n, and process P511 to determine whether the frequency fr(n) of the nth class of the histogram of start time T1 is equal to or lower than the frequency fr(n+1) of the n+1th class. When the startability determination unit 203 determines in process P511 that the frequency continues to increase and the condition is satisfied (YES), it repeats processes P510 and P511 to increment the parameter n by 1.

[0045] Furthermore, when the frequency has changed from an increase to a decrease and it is determined in process P511 that the condition is no longer satisfied (NO), the startability determination unit 203 executes process P512 for recording a third feature point SP3 in the storage device 122. Here, the startability determination unit 203 records, for example, the minimum, average, median or maximum value of the start time T1 in the class number corresponding to the parameter n when the condition of process P511 is no longer satisfied, as the third feature point SP3 in the storage device 122. This third feature point SP3 corresponds, for example, to the second peak in the histogram in FIG. 6.

[0046] 7 and 3, and executes process P6 for determining whether the idle time Tid during which the engine 102 continues idling exceeds a predetermined threshold value Tth. Here, the threshold value Tth can be set to a time, such as 30 seconds, that allows sufficient recording of start-related data required for diagnosing the startability of the engine 102 in the storage device 122. The start-related data includes, for example, the rotation speed, the fuel flow rate FF, the hydraulic oil temperature, the tilt angle of the swash plate of the fuel pump 106, and the like.

[0047] In this process P6, if the startability determination unit 203 determines that the idle time Tid is equal to or less than the predetermined threshold value Tth (NO), it repeats process P6. Also, if the startability determination unit 203 determines that the idle time Tid exceeds the predetermined threshold value Tth (YES), it executes process P7 for determining whether or not to continue work. In this process P7, the startability determination unit 203 determines, for example, whether or not the work machine 100 will continue work.

[0048] In process P7, for example, if the rotation speed of the engine 102 is higher than the idle rotation speed, or if the tilt angle of the swash plate of the fuel pump 106 is greater than a predetermined angle, the startability determination unit 203 determines that the work machine 100 will continue working (YES), and repeats process P7. On the other hand, in process P7, for example, if the rotation speed of the engine 102 is the idle rotation speed, or if the tilt angle of the swash plate of the fuel pump 106 is equal to or smaller than a predetermined angle, the startability determination unit 203 determines that the work machine 100 will not continue working (NO), and executes process P8 to reduce the rotation speed of the engine 102 to the idle rotation speed and stop the engine 102. Thereafter, the engine diagnosis device 200 executes a startability diagnosis P9 of the engine 102, for example, as shown in FIG. 3.

[0049] Fig. 8 is a flow diagram illustrating the details of the startability diagnosis P9 in Fig. 3. When the engine diagnosis device 200 starts the startability diagnosis P9 shown in Fig. 8, for example, it executes a process P901 for determining whether or not an abnormality was diagnosed in the previous startability diagnosis P9.

[0050] In this process P901, the startability determination unit 203 determines that the condition is not satisfied (NO), for example, if the startability of the engine 102 has been diagnosed as good in process P906 (described later) of the previous startability diagnosis P9 and the diagnosis result has been stored in the storage device 122. In this case, the startability determination unit 203 executes, for example, process P902 to set a parameter N for counting the number of times that the startability of the engine 102 has been consecutively determined to be poor to zero. Thereafter, the startability determination unit 203 executes process P903 to select two feature points from feature points SP1, SP2, and SP3 of the histogram shown in FIG.

[0051] Furthermore, in process P901, the startability determination unit 203 determines that the condition is satisfied (YES) if, for example, the engine 102 has been diagnosed as having poor startability in process P909 (described later) of the previous startability diagnosis P9 and the diagnosis result has been stored in the storage device 122. In this case, the startability determination unit 203 executes the next process P903 without executing process P902 for setting the above-mentioned parameter N for counting poor startability to zero.

[0052] In process P903, the startability determination unit 203 selects two feature points from the first feature point SP1, the second feature point SP2, and the third feature point SP3 in the histogram of the start time T1 of the engine 102 shown in Fig. 6. Here, a first embodiment will be described in which the startability determination unit 203 selects the first feature point SP1 and the third feature point SP3. Note that the two feature points selected by the startability determination unit 203 may be determined in advance, or may be selected by an operation by the user of the working machine 100.

[0053] Next, in process P904, the startability determination unit 203 calculates the difference in start time T1 between the two selected feature points. In the first embodiment, as shown in Fig. 6, the startability determination unit 203 calculates the difference DT13 in the start time T1 by subtracting the start time T1 corresponding to the first feature point SP1 from the start time T1 corresponding to the third feature point SP3, and stores the difference DT13 in the start time T1 in the storage device 122. Next, the startability determination unit 203 executes process P905 to determine, for example, whether or not the difference DT13 in the start time T1 exceeds a threshold value TH.

[0054] Here, the threshold value TH can be set in advance, for example, based on the history data of the feature points SP1, SP2, SP3 acquired in the work machine 100 to be diagnosed or other work machines 100 of the same type, and the corresponding determination result of the quality of the startability of the engine 102. More specifically, for example, in the above-mentioned history data, twice the average value of the difference in start time T1 between two selected feature points can be set as the threshold value TH. Furthermore, the threshold value TH may be set based on individual differences in the work machines 100. Hereinafter, the threshold value TH of the difference DT13 in the start time T1 between the first feature point SP1 and the third feature point SP3 will be referred to as the first threshold value TH1.

[0055] In process P905, for example, if the difference DT13 in the start time T1 between the first characteristic point SP1 and the third characteristic point SP3 does not exceed the first threshold value TH1, the startability determination unit 203 determines that the condition is not satisfied (NO). In this case, the startability determination unit 203 executes process P906 to store in the storage device 122 that the startability is good as a result of the startability diagnosis of the engine 102. Thereafter, the engine diagnosis device 200 ends the startability diagnosis P9 in Figures 3 and 8, and ends the process flow shown in Figure 3 and repeats it at a predetermined period.

[0056] On the other hand, in process P905, if the difference DT13 in the start time T1 between the first characteristic point SP1 and the third characteristic point SP3 exceeds the first threshold value TH1, for example, the startability determination unit 203 determines that the condition is met (YES). In this case, the startability determination unit 203 executes process P907 to add 1 to a parameter N for counting the number of times the startability of the engine 102 has become poor, and process P908 to determine whether the parameter N has reached a predetermined value. Here, an example will be described in which the predetermined value of the parameter N is set to 3, but this predetermined value can be set to any integer.

[0057] In process P908, for example, if the parameter N is less than 3, the startability determination unit 203 determines that the condition is not met (NO). In this case, the engine diagnostic device 200 ends the startability diagnosis P9 in Figures 3 and 8, and ends and repeats the process flow shown in Figure 3 at a predetermined cycle. On the other hand, in process P908, for example, if the parameter N reaches 3, that is, if the engine 102 has been diagnosed multiple times in succession as having poor startability, the startability determination unit 203 determines that the condition is met (YES).

[0058] In this case, the startability determination unit 203 executes a process P909 in which, for example, the result of the startability diagnosis of the engine 102 is that the startability is poor, and the process stores this in the storage device 122. In this manner, the engine diagnosis device 200 of this embodiment confirms the diagnosis of poor startability only when the engine 102 has been diagnosed as having poor startability multiple times in succession. This prevents the startability from being unnecessarily determined to be poor when the difference DT13 in the start time T1 suddenly increases and exceeds the first threshold value TH1, and then continues to fall below the first threshold value TH1.

[0059] Thereafter, the startability determination unit 203 executes, for example, process P910 to issue a warning that a startability defect has been diagnosed for the engine 102. In this process P910, the startability determination unit 203, for example, displays a warning on the monitor 107, emits a voice or warning sound via a speaker or buzzer installed in the driver's cab of the work machine 100, or transmits warning information via a wireless communication line or network.

[0060] This allows the user, manager, or service person of the work machine 100 to recognize that a startability problem has been diagnosed for the engine 102 of the work machine 100, and to take appropriate measures. Thereafter, the engine diagnostic device 200 ends the startability diagnosis P9 in Figures 3 and 8, and ends the processing flow shown in Figure 3, and repeats it at a predetermined cycle.

[0061] As described above, the engine diagnostic device 200 of this embodiment diagnoses the startability of the engine 102 for a working machine 100 having a hydraulic pump 101, an engine 102 that rotates the hydraulic pump 101, and a revolution speed detection device 111 that detects the revolution speed of the engine 102. The engine diagnostic device 200 includes a history data recording unit 201, a histogram generating unit 202, and a startability determining unit 203. The history data recording unit 201 calculates a start time T1 from the start of the engine 102 to the time when the revolution speed of the engine 102 reaches a predetermined revolution speed based on the revolution speed of the engine 102 acquired from the revolution speed detection device 111, and records the calculated time T1 as history data. The histogram generating unit 202 generates a histogram of the start time T1 based on the history data of the start time T1 recorded by the history data recording unit 201. The startability determination unit 203 determines the quality of the startability of the engine 102 based on the differences DT13, DT12, and DT23 in the start times T1 of any two of the first feature point SP1, the second feature point SP2, and the third feature point SP3 in the histogram generated by the histogram generation unit 202. The first feature point SP1 is a boundary where the frequency of the start time T1 changes from an increase to a decrease in the histogram of the start time T1. The second feature point SP2 is a boundary where the frequency of the start time T1 changes from a decrease to an increase. The third feature point SP3 is longer than the start time T1 at the second feature point SP2 and is a boundary where the frequency of the start time T1 changes from an increase to a decrease.

[0062] With this configuration, the engine diagnosis device 200 of this embodiment can diagnose the startability of the engine 102 based on the characteristic points SP1, SP2, and SP3 that are specific to a histogram generated based on the history data of the start time T1 of the engine 102 that rotates the hydraulic pump 101. More specifically, as shown in FIG. 6, the histogram of the start time T1 has characteristic points such as a first characteristic point SP1 where the frequency first peaks, a second characteristic point SP2 where the frequency decreases after the first peak and becomes a valley, and a third characteristic point SP3 where the frequency reaches a second peak. Such characteristic points SP1, SP2, and SP3 are particularly noticeable in the four-cylinder engine 102 mechanically connected to the hydraulic pump 101, for example. This is because in the four-cylinder engine 102, the first fuel injection and ignition occur in the first cylinder, so that the difference in the crankshaft angle before starting affects the start time T1. The engine diagnosis device 200 of this embodiment can diagnose the quality of the startability of the engine 102 by, for example, comparing the differences DT13, DT12, DT23 in the start time T1 between two of these characteristic points SP1, SP2, SP3 with the respective threshold values ​​TH. Therefore, according to the engine diagnosis device 200 of this embodiment, it is possible to more easily and accurately diagnose the startability of the engine 102 compared to a case in which the threshold value for the start time T1 is set based on the time series distribution of the start time data.

[0063] As a result, the user or manager of the work machine 100 can formulate a maintenance plan or a purchase plan for a new work machine 100 based on the startability diagnosis result of the engine 102 of the work machine 100. Furthermore, by understanding the startability diagnosis result of the engine 102 of the work machine 100, the service personnel of the work machine 100 can propose to the user of the work machine 100 that the work machine 100 be repaired or a new purchase be made. Furthermore, in the above-mentioned data processing P4, the engine diagnosis device 200 of this embodiment performs processing similar to the data processing described in paragraphs 0039 to 0046, Figs. 7 and 8 of the above-mentioned Patent Document 1. Therefore, according to the engine diagnosis device 200 of this embodiment, it is possible to achieve the same effects as those described in paragraphs 0029 to 0031 of Patent Document 1.

[0064] Furthermore, in the engine diagnosis device 200 of this embodiment, the startability determination unit 203 determines that the startability of the engine 102 is poor when the difference DT13 in the start time T1 between the first characteristic point SP1 and the third characteristic point SP3 exceeds the first threshold value TH1. This makes it possible to diagnose whether the startability of the engine 102 is good or bad based on the difference DT13 in the start time T1 between the first characteristic point SP1 and the third characteristic point SP3, which appears relatively prominently in the histogram of the start time T1. Therefore, the engine diagnosis device 200 of this embodiment makes it possible to more easily and accurately diagnose the startability of the engine 102.

[0065] As described above, the startability determination unit 203 can also diagnose the startability of the engine 102 based on the difference DT12 in the start time T1 between the first characteristic point SP1 and the second characteristic point SP2, or the difference DT23 in the start time T1 between the second characteristic point SP2 and the third characteristic point SP3. These examples will be described below as a second embodiment and a third embodiment, respectively.

[0066] Fig. 9 is a flow diagram for explaining details of the data evaluation P5 in Fig. 3 in the second embodiment. The process flow of the data evaluation P5' in the second embodiment differs from the process flow of the data evaluation P5 in the first embodiment in that after the above-mentioned process 509, process P513 for recording the second feature point SP2 is carried out without carrying out processes P510 to P512 for detecting and recording the third feature point SP3.

[0067] That is, in the second embodiment, the startability determination unit 203 of the engine diagnosis device 200 determines poor startability of the engine 102 when a difference DT12 in start time T1 between the first characteristic point SP1 and the second characteristic point SP2 exceeds a second threshold TH2, which is a threshold TH different from the first threshold TH1, as shown in Fig. 6. This makes it possible to omit processes P510 to P512 for detecting and recording the third characteristic point SP3. Therefore, according to the engine diagnosis device 200 of this embodiment, it is possible to more easily and accurately diagnose the startability of the engine 102.

[0068] Fig. 10 is a flow diagram illustrating details of data evaluation P5 in Fig. 3 in the third embodiment. The processing flow of data evaluation P5'' in the third embodiment differs from the processing flow of data evaluation P5 in the first embodiment in that process P507 for recording the first feature point SP1 is omitted and process P513 for recording the second feature point SP2 is performed as in the second embodiment.

[0069] That is, in the third embodiment, the startability determination unit 203 of the engine diagnosis device 200 determines poor startability of the engine 102 when a difference DT23 in start time T1 between the second characteristic point SP2 and the third characteristic point SP3 exceeds a third threshold value TH3 which is a threshold value TH different from the first threshold value TH1 and the second threshold value TH2, as shown in Fig. 6. As a result, according to the engine diagnosis device 200 of the present embodiment, it is possible to perform startability diagnosis of the engine 102 more easily and with higher accuracy, as in the first and second embodiments.

[0070] An embodiment of the engine diagnosis device according to the present disclosure has been described in detail above using the drawings. However, the specific configuration is not limited to this embodiment, and even if there are design changes and the like within the scope that does not deviate from the gist of the present disclosure, they are included in the present disclosure. [Explanation of symbols]

[0071] 100 Work Machines 101 Hydraulic pump 102 Engine 111 Rotational speed detector 200 Engine diagnostic equipment 201 History data recording unit 202 Histogram Generation Unit 203 Startability judgment unit DT12 Difference DT13 Difference DT23 difference SP1 First feature point SP2 Second feature point SP3 3rd feature point T1 Start-up time

Claims

1. An engine diagnosis device for diagnosing startability of an engine of a work machine having a hydraulic pump, an engine that rotates the hydraulic pump, and a rotation speed detection device that detects the rotation speed of the engine, comprising: a history data recording unit that calculates a start time from when the engine is started until the engine speed reaches a predetermined speed based on the engine speed obtained from the engine speed detection device, and records the calculated start time as history data; a histogram generating unit that generates a histogram of the start times based on the history data recorded by the history data recording unit; a startability determination unit that determines whether the startability of the engine is good or bad based on a difference in start time between any two of a first characteristic point on the histogram generated by the histogram generation unit, which is a boundary where the frequency of the start time changes from an increase to a decrease, a second characteristic point on the boundary where the frequency of the start time changes from a decrease to an increase, and a third characteristic point that is longer than the start time at the second characteristic point and is a boundary where the frequency of the start time changes from an increase to a decrease; An engine diagnostic device comprising:

2. The engine diagnosis device according to claim 1, wherein the startability determination unit determines that the engine has poor startability when the difference in the start time between the first characteristic point and the third characteristic point exceeds a first threshold value.

3. The engine diagnosis device according to claim 1, wherein the startability determination unit determines that the engine has poor startability when the difference in the start time between the first characteristic point and the second characteristic point exceeds a second threshold value.

4. The engine diagnosis device according to claim 1, wherein the startability determination unit determines that the startability of the engine is poor when the difference in the start time between the second characteristic point and the third characteristic point exceeds a third threshold value.

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