Construction machine

Abstract

To provide a construction machine capable of grasping and maintaining a state of the suspension around a crawler through estimation on load inputted in a driving device of a crawler traveling device with a simple configuration.SOLUTION: For a construction machine provided with a traveling device having a crawler, detection sensors (40, 42) detecting correlation value of bolt shaft force are arranged on a bolt (36A) positioned at a six o'clock direction of a short hand of a clock, and on a bolt (36B) positioned at a three o'clock direction of a short hand of a clock when viewing a left side of the traveling device from the outside and positioned at a nine o'clock when viewing a right side of the traveling device from the outside among a plurality of bolts (36) fixing a driving device (30) on a side frame such that a bolt shaft line becomes perpendicular to a side surface of the side frame (27), being provided with a control device determining a state of the traveling device on a basis of information from the detecting sensor. The control device determines a state of the traveling device by calculating the bolt shaft forces F1, F2 from the correlation value of the shaft force detected with the detecting sensors to dispatch alarm upon determination of an abnormal state of the traveling device.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a construction machine having a crawler-type traveling device. [Background technology]

[0002] Construction machinery such as hydraulic excavators are designed to travel on unleveled ground and are generally configured as tracked vehicles with track-type traveling devices on both the left and right sides of a lower traveling body. A tracked vehicle is configured with endless tracks wound around drive wheels, idler wheels, and multiple rollers of a drive device provided on the traveling device. When the left and right drive wheels are rotated by a hydraulic traveling motor provided on the drive device, the left and right tracks are driven independently while being guided by the idler wheels and each roller, and the hydraulic excavator travels straight or steers depending on the drive direction and drive speed of the left and right tracks.

[0003] The drive unit receives a resultant force mainly consisting of track tension, excavation force, and reaction force due to the vehicle weight. If the operating environment of a track-type traveling device is poor or the track tension is not appropriate, the track tension and reaction force due to the vehicle weight will increase, and this resultant force will also increase. Because excessive resultant force places unnecessary strain on the internal components of the drive unit, it is necessary to maintain the drive unit and the undercarriage around the track in good condition. It is therefore desirable to measure the load on the undercarriage around the track from the track tension, excavation force, reaction force due to the vehicle weight, and the resultant force of these forces input to the drive unit.

[0004] For example, in a work vehicle such as a tractor, in which a track-type traveling device is connected to the engine via a power shift transmission or continuously variable transmission, a technology for measuring the load on the undercarriage around the track is known, in which a sensor is attached to the pivot pin of the track assembly connected to the body to measure the axle load, and the engine torque output of the work vehicle is controlled based on the difference in axle load (Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US Patent Application Publication No. 2017 / 0242447 Summary of the Invention [Problem to be solved by the invention]

[0006] A track-type traveling device provided on the undercarriage of a tracked vehicle such as a hydraulic excavator generally comprises a pair of side frames provided on the left and right of a track frame, a plurality of upper rollers provided on the upper side of the side frames at a distance in the fore-and-aft direction, a plurality of lower rollers provided on the lower side of the side frames at a distance in the fore-and-aft direction, a drive unit provided on one end of each side frame, an idler wheel provided on the other end of each side frame, drive wheels (sprockets) provided on the drive unit, and a track wound around the idler wheel. The drive unit further comprises a hydraulic motor as a rotation source, and a reduction gear that reduces the rotation of the hydraulic motor and outputs it to the drive wheels.

[0007] Tracked vehicles such as hydraulic excavators configured in this manner have a structure that is significantly different from that of work vehicles such as tractors disclosed in Patent Document 1. This means that the running gear does not have a part equivalent to a pivot pin, and the output shaft of the reduction gear to the drive wheels is a rotating body, making it difficult to install a sensor that measures the load directly input to the drive gear. As a result, it is not possible to measure the load on the undercarriage around the tracks that is input to the drive gear in the same way as the technology disclosed in Patent Document 1.

[0008] The present invention has been made to solve these problems, and its object is to provide a construction machine with a simple configuration that can estimate the load input to the drive unit of a track-type traveling device, and can accurately grasp and maintain the condition of the undercarriage around the tracks. [Means for solving the problem]

[0009] In order to achieve the above object, the construction machine of the present invention is a construction machine having a lower traveling body, the lower traveling body being provided with a plurality of upper rollers provided at intervals in the longitudinal direction on each of a pair of left and right side frames of a track frame, the upper side of the side frames and the lower side rollers provided at intervals in the longitudinal direction on the lower side of the side frames, a drive unit provided with a drive wheel on one end side of the side frames in the longitudinal direction, an idler wheel provided on the other end side of the side frames, and a traveling unit having a track belt wound around the drive wheel and the idler wheel, the drive unit being fixed to the side frames by a plurality of bolts whose bolt axes are perpendicular to the side faces of the side frames, and at least one of the plurality of bolts being located at the lowest position in the vertical direction when the track belt is in contact with the ground. The system comprises a plurality of detection sensors provided on a first bolt and a second bolt located at the end of the side frame in the longitudinal direction, each detecting a correlation value of the bolt axial force acting on the bolt; a control device that determines the state of the traveling device based on detection information from the detection sensors; and an alarm device that issues an alarm based on a signal from the control device, wherein the control device calculates bolt axial forces including at least a first bolt axial force acting on the first bolt and a second bolt axial force acting on the second bolt from the correlation values ​​of the bolt axial forces detected by the detection sensors, determines the state of the traveling device based on the calculated bolt axial forces, and if it determines that the traveling device is in an abnormal state, sends a signal corresponding to the abnormal state to the alarm device. [Effects of the Invention]

[0010] With the construction machine of the present invention, it is possible to accurately grasp the condition of the undercarriage around the tracks of the traveling gear, etc. by estimating the track tension, excavation force, and reaction force due to the vehicle weight input to the drive unit, and if an abnormal condition is detected, an appropriate warning is issued and appropriate measures can be taken on the traveling gear. This allows the condition of the suspension around the crawler to be kept appropriate, and reduces the input of unnecessary load to the traveling device. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a side view of a hydraulic excavator having a crawler-type traveling device according to the present invention mounted on a lower traveling body. [Figure 2] FIG. 2 is an enlarged view of the drive unit seen from the hydraulic motor side with the crawler removed, showing the mounting positions of strain gauges. [Figure 3] 2 is a view of one end side of the traveling device in the longitudinal direction with the crawler removed, as viewed from the direction of arrow A in FIG. 1, showing the attached state of strain gauges. [Figure 4] 1 is a block diagram showing a configuration of a control device according to the present invention; [Figure 5] FIG. 1 is a side view of a crawler-type traveling device according to the present invention, showing a state in which a load is applied from below. [Figure 6] As in Figure 3, this is a view from the direction of arrow A in Figure 5, showing a situation in which a moment load is generated in the drive unit when a load is applied to the traveling unit from below, and a tensile load is applied to the bolt at the 6 o'clock position. [Figure 7] 10A and 10B are diagrams illustrating a state in which the track tension increases and a tensile load is applied to the drive unit. [Figure 8] 8 is a diagram viewed from the direction of arrow B in FIG. 7, showing a situation in which a moment load is generated in the drive unit when a tensile load is applied to the drive unit due to an increase in track tension, and a tensile load is applied to the bolts in the 3 o'clock / 9 o'clock direction. [Figure 9] 4 is a flowchart of an abnormality determination routine executed by the control device. [Figure 10] 10 is a time chart showing the relationship between the change over time of the resultant force Fall of the bolt axial force F1 and the bolt axial force F2 calculated in the calculation and determination unit and the threshold value Fallmax. [Figure 11] 10 is a time chart showing the relationship between the change over time of the bolt axial force F1 calculated in the calculation / determination unit and the threshold value F1max. [Figure 12] 10 is a time chart showing the relationship between the change over time of the bolt axial force F2 calculated in the calculation / determination unit and the threshold values ​​F2max and F2min. [Figure 13] 10 is a time chart showing the relationship between the change over time of the bolt axial force F2 calculated in the calculation / determination unit and the threshold values ​​F2max and F2min. [Figure 14] This is a conceptual diagram showing the relationship between bolt axial forces F1, F2 and resultant force Fall and thresholds F1max, F2max, F2min and Fallmax, with the vertical axis representing bolt axial force F1 and the horizontal axis representing bolt axial force F2. [Figure 15] This is a histogram showing the relationship between the value of the fluctuating resultant force Fall and the number of repetitions, with the horizontal axis representing the load distribution and the vertical axis representing the number of repetitions. [Figure 16] 16 is a chart showing the cumulative load Fc as the total integrated value of the load in each load range in the histogram of FIG. 15, with the cumulative number of repetitions of the fluctuating resultant force Fall on the horizontal axis and the cumulative load Fc on the vertical axis. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a construction machine according to the present invention will be described using a hydraulic excavator as an example. FIG. 1 is a side view showing a hydraulic excavator 1, and first, a schematic configuration of the hydraulic excavator 1 will be described based on this drawing.

[0013] The hydraulic excavator 1 is a tracked vehicle that is generally composed of a self-propelled tracked (crawler) lower traveling body 2, an upper rotating body 3 that is rotatably mounted on the lower traveling body 2, and a working device 4 that is mounted on the front side of the upper rotating body 3 so that it can be raised and lowered and that performs work to excavate earth and sand. The working device 4 is composed of a boom 5, an arm 6, and a bucket 7, and the angle of the boom 5 is changed by a boom cylinder 5a, the angle of the arm 6 is changed by an arm cylinder 6a, and the angle of the bucket 7 is changed by a bucket cylinder 7a.

[0014] The upper rotating structure 3 is provided with an operator's cab 8 where an operator sits, a machine room 9, a counterweight 10, etc. The machine room 9 accommodates machinery such as an engine (not shown), a hydraulic pump (not shown) driven by the engine, and a hydraulic control device that adjusts the pressure of pressurized oil from the hydraulic pump in response to operation by the operator. The hydraulic pump supplies pressurized oil to the boom cylinder 5a, arm cylinder 6a, bucket cylinder 7a, a swing hydraulic motor (not shown) that swings the upper rotating structure 3, and a hydraulic motor 32, which will be described later.

[0015] A track-type traveling device 20 is provided on each of the left and right sides of the undercarriage 2. The traveling device 20 is generally composed of a pair of side frames 22 provided on the left and right sides of a track frame 21, a plurality of upper rollers 23 provided on the upper side of the side frames 22 at intervals in the longitudinal direction of the side frames 22, a plurality of lower rollers 24 provided on the lower side of the side frames 22 at intervals in the longitudinal direction of the side frames 22, a drive unit 30 provided on one longitudinal end of each side frame 22, an idler wheel 25 provided on the other longitudinal end of each side frame 22, a drive sprocket (drive wheel) 31 provided on the drive unit 30, and an endless track 26 wound around the idler wheel 25. As will be described later, the drive unit 30 is composed of a hydraulic motor 32 that serves as a rotation source for the drive sprocket 31, and a reduction gear 34.

[0016] 2 shows an enlarged view of the drive unit 30 as seen from the inside of the traveling device 20, i.e., the hydraulic motor 32 side, with the tracks 26 removed. FIG. 3 shows an enlarged view of the drive unit 30 as seen from one end of the traveling device 20 in the longitudinal direction, with the tracks 26 removed, from the direction of arrow A in FIG. 1.

[0017] 2 and 3, a bracket (side frame) 27 for attaching a drive unit 30 is joined to one longitudinal end of the side frame 22 as an extension of the side frame 22. The drive unit 30 is configured by integrally including a hydraulic motor 32 and a reduction gear 34 that reduces the rotation of the hydraulic motor 32 and outputs it to a drive sprocket 31, and is fastened to the side surface of the bracket 27 with a plurality of bolts 36. Note that although the reference numeral 'reduction gear 34' is used in FIGS. 2 and 3, the main body of the reduction gear 34 is housed as a gear mechanism on the inner peripheral side of the drive sprocket 31, although not shown.

[0018] 2 and 3 , a circular opening 28 is provided in a side surface of the bracket 27 (a side surface of the side frame), and a plurality of bolt through holes 29 are provided in a row at regular intervals along the periphery of this opening 28. A flange portion 37 is formed in the reduction gear 34 so as to surround the hydraulic motor 32. The reduction gear 34 is fastened to the bracket 27 by bolts 36 inserted through each bolt through hole 29 and the flange portion 37. That is, the bolts 36 are screwed into the flange portion 37 of the reduction gear 34 so that the bolt axes are perpendicular to the side surface of the bracket 27, and fasten the drive unit 30 to the bracket 27.

[0019] The hydraulic motors 32 are rotationally driven by a supply of pressurized oil generated by a hydraulic pump in the machinery room 9 and whose pressure is adjusted by a hydraulic control device. The rotational drive force of the hydraulic motors 32, whose magnitude corresponds to the discharge force of the pressurized oil, is transmitted to the tracks 26 via a reduction gear 34 and a drive sprocket 31. The left and right hydraulic motors 32 can operate in forward and reverse directions independently. This allows the drive direction and drive force of the left and right tracks 26 to be individually controlled in response to operation by the operator, allowing the undercarriage 2 to move forward, backward, and turn.

[0020] As shown in Fig. 2, a strain gauge (detection sensor) 40 is attached to one of the bolts 36 (first bolt) 36A located at the 6 o'clock position (hereinafter referred to as the 6 o'clock position), i.e., the lowest bolt in the vertical direction when the crawler belt 26 is in contact with the ground. Similarly, a strain gauge (detection sensor) 42 is attached to one of the bolts (second bolt) 36B located at the 3 o'clock position when the left (illustrated) traveling device 20 is viewed from the outside, and at the 9 o'clock position when the right (not shown) traveling device 20 is viewed from the outside (hereinafter collectively referred to as the 3 o'clock / 9 o'clock position), i.e., the endmost bolt on one end of the longitudinal direction of the side frame 22. More specifically, as shown in Fig. 3 for bolt 36A, strain gauges 40 and 42 are embedded in bolts 36A and 36B. As a result, when the bolts 36A, 36B are expanded or contracted due to an axial load, i.e., bolt axial force, the axial strain of the bolts 36A, 36B corresponding to the bolt axial force (amount of displacement: correlation value of bolt axial force) is detected by the strain gauges 40, 42. The strain gauges 40, 42 are electrically connected to a control device 50, which will be described later, and strain information detected by the strain gauges 40, 42 is supplied to the control device 50.

[0021] Referring to FIG. 4, a block diagram shows the configuration of a control device 50 according to the present invention, which is one of the control devices mounted on the hydraulic excavator 1 and which performs various controls such as the control of the hydraulic control device. The control device 50 is configured to include an information input unit 52, a calculation and judgment unit 54, a memory 56, and a judgment result output unit 58. When strain information from the strain gauges 40, 42 is input to the information input unit 52, the input information is converted into a bolt axial force by the calculation and judgment unit 54, and a judgment is made as to whether the bolt axial force is within a normal range or abnormal by referring to judgment reference values ​​pre-stored in the memory 56. This judgment result is output (transmitted) as a signal from the judgment result output unit 58 to a driver's seat monitor (alarm device) 60 in the driver's cab 8, and is displayed (issued). The strain information input from the strain gauges 40, 42, the converted bolt axial force information, and the judgment result are stored in the memory 56, and are output from the judgment result output unit 58 to the driver's seat monitor 60 as needed.

[0022] The operation of the construction machine having the traveling device 20 and the control device 50 configured as described above will be described below. Fig. 5 shows a state in which the traveling device 20 runs over, for example, a stone 70 and a load (white arrow) is applied from below. Fig. 6, similar to Fig. 2, shows a view from the direction of arrow A in Fig. 5, in which when a load (white arrow) is applied from below to the traveling device 20, a moment load (white curved arrow) is generated in the reduction gear 34 and, by extension, the drive device 30, and a load (solid arrow) in the tensile direction is applied to the bolt 36A in the 6 o'clock direction.

[0023] 7 shows a state in which the tension of the crawler belt 26, i.e., the track tension, increases and a tensile load (white arrow) is applied to the drive unit 30. 8 shows a state in which, when the track tension increases and a tensile load (white arrow) is applied to the drive unit 30, a moment load (white curved arrow) is generated in the reduction gear 34 and, in turn, in the drive unit 30, and a tensile load (solid arrow) is applied to the bolt 36B in the 3 o'clock / 9 o'clock direction.

[0024] Hereinafter, a situation in which a tensile load is applied to the bolts 36A, 36B as shown in FIGS. 5 to 8 will be described using examples [Example 1] to [Example 4]. [Example 1] When the reaction force due to the weight of hydraulic excavator 1 increases When the traveling device 20 runs over the stone 70, as shown in Fig. 5, a load is applied as a reaction force from the underside of the traveling device 20 (near the 6 o'clock position) via the drive sprocket 31 to the reduction gear 34 and ultimately to the driving device 30. At this time, as shown in Fig. 6, this reaction force generates a moment load on the driving device 30 around the rotation axis of the driving device 30. A tensile load acts mainly on the bolt 36A in the 6 o'clock position, and the strain gauge 40 attached to the bolt 36A detects strain corresponding to this load.

[0025] Furthermore, when the hydraulic excavator 1 performs a so-called jack turn, in which the idler wheel 25 side of the traveling device 20 is lifted to change direction, a moment load is generated around the rotation axis of the driving device 30 due to a reaction force, just as when the traveling device 20 runs over a stone 70. This also causes a tensile load to act mainly on the bolt 36A in the 6 o'clock direction, and the strain gauge 40 attached to the bolt 36A detects strain corresponding to this load.

[0026] [Example 2] When the traveling device 20 is clogged with earth and sand When soil and sand accumulates inside the traveling unit 20, the tension of the tracks 26 increases compared to the appropriate tension state, and a tensile load due to the track tension is applied to the reduction gear 34 and, ultimately, to the drive unit 30, as shown in Fig. 7. At this time, a moment load is generated in the drive unit 30 about the rotation axis of the drive unit 30, as shown in Fig. 8. The tensile load acts mainly on the bolts 36B in the 3 o'clock / 9 o'clock direction, and the strain gauges 42 attached to the bolts 36B detect strain corresponding to this load.

[0027] [Example 3] When the tension of the track 26 is loose If the tension of the track 26 is loose, the drive sprocket 31 may ride over the pins provided on the track 26 while the hydraulic excavator 1 is traveling, i.e., "tooth skipping" may occur. This also increases the track tension, and a tensile load due to the track tension is applied to the reduction gear 34 and, ultimately, to the drive unit 30. As shown in FIG. 8, a moment load is also generated in the drive unit 30 about the rotation axis of the drive unit 30, and a tensile load acts mainly on the bolts 36B in the 3 o'clock / 9 o'clock direction, and the strain gauges 42 attached to the bolts 36B detect strain corresponding to this load.

[0028] If the tension on the track 26 is loose, proper track tension cannot be obtained when the hydraulic excavator 1 is stopped, and therefore the reduction gear 34, and in turn the drive unit 30, are not subjected to the proper tensile load due to the track tension. As a result, the moment load that would normally occur around the rotation axis of the drive unit 30 is not generated in the drive unit 30, and the load in the tensile direction acting mainly on the bolt 36B in the 3 o'clock / 9 o'clock direction is insufficient, and the strain gauge 42 attached to the bolt 36B detects a small strain corresponding to that load.

[0029] [Example 4] When an excessive load is applied to hydraulic excavator 1 When the hydraulic excavator 1 climbs a steep slope with the drive unit 30 facing forward of the traveling unit 20, the traveling unit 20 temporarily becomes suspended and does not touch the ground just before reaching the top of the slope. Subsequently, when the traveling unit 20 returns to a grounded state due to the weight of the hydraulic excavator 1, it collides with the ground. In this case, the collision of the traveling unit 20 applies a load greater than expected to the reduction gear 34 and, in turn, to the drive unit 30, generating a moment load on the drive unit 30 about its rotation axis. In this case, a tensile load often acts on both the 6 o'clock bolt 36A and the 3 o'clock / 9 o'clock bolts 36B, and strain gauges 40, 42 attached to bolts 36A, 36B detect strain corresponding to this load.

[0030] FIG. 9 shows a flowchart of an abnormality determination routine executed by the control device 50, and the following description will be given with reference to this flowchart. In step S10, first, the bolt axial force at the time of shipment of the construction machine body is set as a reference (0). More specifically, when the hydraulic excavator 1 is shipped, the hydraulic excavator 1 is placed on level ground and strain is detected by the strain gauge 40 of the bolt 36A in the 6 o'clock position and the strain gauge 42 of the bolt 36B in the 3 o'clock / 9 o'clock position. The bolt axial forces applied to the bolts 36A and 36B are calculated based on the detected strain values ​​in the calculation and determination unit 54 via the information input unit 52, and these bolt axial forces are stored in the memory 56 as references (0). Then, when step S10 is executed, the bolt axial forces are read out and set as references (0).

[0031] In step S12, the bolt axial forces in two directions, i.e., the bolt axial force of bolt 36A in the 6 o'clock direction is calculated as F1 (first bolt axial force), and the bolt axial force of bolt 36B in the 3 o'clock / 9 o'clock direction is calculated as F2 (second bolt axial force). More specifically, when strain information detected by strain gauge 40 of bolt 36A in the 6 o'clock direction and strain gauge 42 of bolt 36B in the 3 o'clock / 9 o'clock direction is input to information input unit 52, calculation and determination unit 54 calculates bolt axial forces F1, F2 applied to bolts 36A, 36B based on the detected strain values. Note that the calculation of bolt axial forces F1, F2 from the strain values ​​detected by strain gauges 40, 42 is well known, and therefore will not be described here.

[0032] In step S14, based on the bolt axial forces F1 and F2 applied to the bolts 36A and 36B, the calculation and determination unit 54 calculates the resultant force Fall of the bolt axial forces F1 and F2 using the following equation (1), which is the square root of the sum of the squares of the bolt axial forces F1 and F2. Fall=√((F1) 2 +(F2) 2 ) ···(1)

[0033] In step S16, the calculation and determination unit 54 compares the resultant force Fall obtained as described above with a threshold Fallmax (predetermined resultant force threshold) which is a determination reference value stored in the memory 56 in advance. If the comparison in step S16 shows that the resultant force Fall is greater than the threshold Fallmax (judgment result: Yes), the process proceeds to step S18, where the judgment result output unit 58 issues an alarm (warning) to encourage improvement of the operating environment, and the contents of the alarm are displayed on the driver's seat monitor 60.

[0034] The determination result of step S16 may be true (Yes) in various ways, including, for example, the above-described example 4. That is, when excessive loads are applied to the traveling device 20 in both the vertical and horizontal directions, the traveling device 20 temporarily lifts up just before the hydraulic excavator 1 reaches the top of a steep slope with the drive device 30 in front of the traveling device 20, and then the traveling device 20 collides with the ground due to the hydraulic excavator 1's own weight. In this case, the driver's seat monitor 60 displays a warning urging the operator to improve the operating environment, for example, the road surface conditions at the traveling location of the work site. More specifically, the warning displays urging the operator to avoid working on steep slopes as much as possible, to prevent falling rocks from hitting the traveling device 20 at sites with frequent rockfalls, and to avoid using the traveling device 20 to drive over large rocks.

[0035] 10 is a time chart showing the relationship between the threshold Fallmax and the change over time in the resultant force Fall of the bolt axial forces F1 and F2 calculated by the calculation and determination unit 54. In this figure, the resultant force Fall temporarily exceeds the threshold Fallmax, which corresponds to, for example, the case in [Example 4] above where an excessive load is applied to the hydraulic excavator 1. In such a case, as described above, the driver's seat monitor 60 displays a warning urging the driver to improve the operating environment, for example, the road surface conditions at the driving location of the operating site.

[0036] 10, the resultant force Fall of the bolt axial forces F1 and F2 is constantly fluctuating, even though it does not exceed the threshold Fallmax. This is because even under normal circumstances, tractive forces and frictional forces with the ground are generated on the crawler 26 due to the traveling and excavation work of the hydraulic excavator 1, and these influences cause the bolt axial forces F1 and F2 to fluctuate, repeatedly increasing and decreasing.

[0037] On the other hand, if the determination result in step S16 is false (No) and the resultant force Fall is equal to or smaller than the threshold Fallmax, the process proceeds to steps S20 and S30. In step S20, the bolt axial force F1 applied to the bolt 36A calculated in step S12 is compared with a threshold value F1max (first predetermined threshold value) which is a judgment reference value stored in the memory 56 in advance.

[0038] If the bolt axial force F1 is greater than the threshold value F1max in step S20 (determination result: Yes), the process proceeds to step S22, where the calculation and determination unit 54 determines that there is an upward thrust load from below the traveling device 20. Then, the process proceeds to step S24, where the determination result output unit 58 issues an alarm warning about how to use the hydraulic excavator 1, and the content of the alarm is displayed on the driver's seat monitor 60.

[0039] If the determination result in step S20 is true (Yes), the situation corresponds to the above-mentioned [Example 1]. That is, this corresponds to a case where the traveling device 20 runs over a stone 70 or a case where the hydraulic excavator 1 performs a so-called jack turn. As a result, the driver's seat monitor 60 displays a warning message to prevent the driver from running over an obstacle such as the stone 70 or performing a dangerous operation such as a so-called jack turn.

[0040] 11 is a time chart showing the relationship between the change in bolt axial force F1 over time calculated by the calculation / determination unit 54 and the threshold value F1max. In this figure, the bolt axial force F1 temporarily exceeds the threshold value F1max. This situation corresponds to the case in [Example 1] where the reaction force due to the weight of the hydraulic excavator 1 increases, for example, when the traveling device 20 runs over a stone 70. In such a case, the driver's seat monitor 60 displays a warning message, as described above, to avoid running over an obstacle such as a stone 70.

[0041] On the other hand, if the bolt axial force F1 is equal to or less than the threshold value F1max (determination result: No) in step S20, the process proceeds to step S40, where the calculation and determination unit 54 determines that there is no abnormality. In this case, the calculation and determination unit 54 does not cause the driver's seat monitor 60 to display an alarm.

[0042] In step S30, the bolt axial force F2 applied to the bolt 36B calculated in step S12 is compared with a threshold value F2max or a threshold value F2min (second predetermined threshold value) which is a judgment reference value stored in advance in the memory 56.

[0043] In step S30, if the bolt axial force F2 is greater than the threshold value F2max or less than the threshold value F2min (determination result: Yes), the process proceeds to step S32, where the calculation and determination unit 54 determines that the tension of the crawler belt 26 is excessive or insufficient, i.e., that there is an excess or deficiency of track tension. Then, the process proceeds to step S34, where the determination result output unit 58 issues an alarm urging the driver to check the tension of the crawler belt 26, and the content of the alarm is displayed on the driver's seat monitor 60.

[0044] If the determination result in step S30 is true (Yes), this corresponds to the above-mentioned [Example 2] and [Example 3]. That is, this corresponds to a case where earth and sand are clogged inside the traveling device 20 or the tension of the crawler belt 26 is loose, etc. In the case where the tension of the crawler belt 26 is loose in [Example 3], as described above, when the hydraulic excavator 1 is traveling, a tensile load is applied to the crawler belt 26 due to the occurrence of "tooth skipping," and the bolt axial force F2 fluctuates so as to be greater than the threshold value F2max. On the other hand, when the hydraulic excavator 1 is stopped, an appropriate tensile load is not applied to the crawler belt 26, and the bolt axial force F2 becomes smaller than the threshold value F2min.

[0045] In the case of [Example 2], a warning message is displayed on the driver's seat monitor 60 to remove any dirt or sand that has adhered to the tracks 26, the idler wheels 25, and the drive sprocket 31, and in the case of [Example 3], a warning message is displayed on the driver's seat monitor 60 to properly tension the tracks 26.

[0046] 12 is a time chart showing the relationship between the change in bolt axial force F2 calculated by the calculation / determination unit 54 over time and the thresholds F2max and F2min. In this figure, the bolt axial force F2 gradually increases and exceeds the threshold F2max. This corresponds to the case in [Example 2] where earth and sand are clogged inside the traveling device 20, and the driver's seat monitor 60 displays a warning to remove the earth and sand adhering to the crawler belt 26, idler wheel 25, and drive sprocket 31.

[0047] 12, Fig. 13 shows, in a time chart, the relationship between the change over time of the bolt axial force F2 calculated by the calculation / determination unit 54 and the threshold values ​​F2max and F2min. In the figure, the bolt axial force F2 fluctuates so that it is smaller than the threshold value F2min when the hydraulic excavator 1 is stopped, and larger than the threshold value F2max when the hydraulic excavator 1 is traveling. This corresponds to the case in [Example 3] where the tension of the crawler belt 26 is loose, and a warning message is displayed on the driver's seat monitor 60 to prompt the user to properly tension the crawler belt 26.

[0048] On the other hand, if the determination result in step S30 is false (No), the process proceeds to step S40, where the calculation and determination unit 54 determines that there is no abnormality.

[0049] Incidentally, even if an alarm prompting improvement of the operating environment is issued in step S18, the processes from step S20 onwards and the processes from step S30 onwards are further executed.

[0050] This makes it possible to determine whether the bolt axial force in the 6 o'clock direction or the bolt axial force in the 3 o'clock / 9 o'clock direction caused the resultant force Fall to exceed the threshold Fallmax when the resultant force Fall exceeds the threshold Fallmax. In the case of Example 4, the bolt axial force F1 increases mainly in the 6 o'clock direction when the traveling gear 20 collides with the ground, and the bolt axial force F1 often exceeds the threshold F1max. In this case, an alarm is further issued to warn the user about how to use the hydraulic excavator 1. Alternatively, when the tension of the track 26 is relatively high, the bolt axial force F2 increases mainly in the 3 o'clock / 9 o'clock direction, and the bolt axial force F2 often exceeds the threshold F2max. In this case, an alarm is further issued to prompt the user to check the tension of the track 26. This makes it possible to determine which direction of the traveling gear 20 is responsible for the resultant force Fall when an excessively large resultant force Fall is input to the traveling gear 20, and to issue an alarm more appropriately.

[0051] Figure 14 is a conceptual diagram showing the relationship between the bolt axial forces F1, F2 and resultant force Fall, and the thresholds F1max, F2max, F2min and Fallmax, as determined in the abnormality determination routine of Figure 5, with the bolt axial force F1 on the vertical axis and the bolt axial force F2 on the horizontal axis. The conceptual diagram of Figure 14 also shows, as coordinate points, examples of the maximum values ​​of the bolt axial forces F1, F2 and resultant force Fall in the above-mentioned [Example 1] to [Example 4], and the minimum value of the bolt axial force F2 in the [Example 2]. As shown in the conceptual diagram, an alarm is issued when the bolt axial force F1 is greater than the threshold F1max, when the bolt axial force F2 is smaller than the threshold F2min or greater than the threshold F2max, or when the resultant force Fall of the bolt axial forces F1 and F2 is greater than the threshold Fallmax.

[0052] On the other hand, in the same conceptual diagram, if the bolt axial force F1 is equal to or less than the threshold value F1max, if the bolt axial force F2 is equal to or greater than the threshold value F2min and equal to or less than the threshold value F2max, or if the resultant force Fall of the bolt axial forces F1 and F2 is equal to or less than the threshold value Fallmax, the traveling device 20 is not in a particularly abnormal state but is in a normal state and will not issue an alarm.

[0053] As described above, in the construction machine according to the present invention, in the track-type traveling unit 20 provided on the undercarriage 2 of the hydraulic excavator 1, the drive unit 30 is integrally configured with the hydraulic motor 32 and the reduction gear 34 that reduces the rotation of the hydraulic motor 32 and outputs the reduced rotation to the drive sprocket 31, and is fastened by a plurality of bolts 36 to the side surface of the bracket 27 joined to the side frame 22 via the reduction gear 34. A strain gauge 40 is attached to bolt 36A of the plurality of bolts 36, which is located at the 6 o'clock position of the hour hand of a clock, i.e., the lowest position in the vertical direction when the traveling unit 20 is in a state where the traveling unit 20 is in contact with the ground, and a strain gauge 42 is similarly attached to bolt 36B located at the 3 o'clock position of the hour hand of a clock when viewed from the outside of the left traveling unit 20 and at the 9 o'clock position of the hour hand of a clock when viewed from the outside of the right traveling unit 20, i.e., the end portion on one end of the longitudinal direction of the side frame 22 when the traveling unit 20 is in a state where the traveling unit 20 is in contact with the ground.

[0054] This makes it possible to estimate various reaction forces input to the drive unit 30 and accurately grasp the state of the undercarriage around the crawler belt 26 of the traveling unit 20, etc. If an abnormal state is detected in the undercarriage, an appropriate warning is issued, so that appropriate measures can be taken for the traveling unit 20. This keeps the suspension in an appropriate state and prevents unnecessary load from being applied to the traveling device 20.

[0055] 10, while the hydraulic excavator 1 is in operation, the bolt axial force F1 and the bolt axial force F2 fluctuate, repeatedly increasing and decreasing due to travel, excavation work, etc. of the hydraulic excavator 1. Such fluctuations in the magnitude of the bolt axial force F1 and the bolt axial force F2 result in a constant load being applied to the reduction gear 34 and, in turn, the drive unit 30, even if the bolt axial force F1 is equal to or less than the threshold value F1max, the bolt axial force F2 is equal to or greater than the threshold value F2min and equal to or less than the threshold value F2max, or the resultant force Fall of the bolt axial forces F1 and F2 is equal to or less than the threshold value Fallmax. This cumulatively leads to fatigue of the reduction gear 34 and, in turn, the drive unit 30, and wear of the components.

[0056] The control device 50 constantly calculates the resultant force Fall of the bolt axial forces F1 and F2 in the calculation and determination unit 54, and stores in memory 56, for example, the relationship between the value of the fluctuating resultant force Fall (for example, each fluctuation peak value) and the number of repetitions of the fluctuating resultant force Fall (corresponding to elapsed time) as a histogram as shown in Fig. 15, with the horizontal axis representing the load distribution and the vertical axis representing the number of repetitions (time). The load distribution is obtained by dividing the load into load ranges at regular intervals, and the histogram is generated by allocating the value of the resultant force Fall calculated as needed to the corresponding load range and accumulating the number of repetitions within that load range.

[0057] The calculation and determination unit 54 further calculates the cumulative load Fc in synchronization with the generation of this histogram, and stores a chart such as that shown in Fig. 16 in the memory 56. Specifically, in this chart, the horizontal axis represents the cumulative number of repetitions (cumulative time) of the fluctuating resultant force Fall, and the vertical axis represents the cumulative load Fc, and the total integrated value of the loads in each load range in the histogram in Fig. 15 (for example, the average load in each load range) is shown as the cumulative load Fc.

[0058] As shown in the figure, a threshold value Fcmax (predetermined cumulative load threshold value) is set, and the calculation and determination unit 54 also determines whether the cumulative load Fc has exceeded the threshold value Fcmax. If the cumulative load Fc exceeds the threshold value Fcmax, it can be assumed that the reduction gear 34, and in turn the drive unit 30, has become fatigued, and that wear or the like has occurred in the components. In this case, an alarm is issued to prompt maintenance and inspection of the internal parts of the traveling device 20, and the content of the alarm is displayed on the driver's seat monitor 60.

[0059] This makes it possible to properly maintain and inspect the traveling gear 20 by determining that the cumulative load Fc, calculated as the integrated value of the resultant force Fall of the bolt axial forces F1 and F2, has exceeded the threshold value Fcmax. In particular, the operating environment and usage method of the hydraulic excavator 1 differ from one another, and for example, at operating sites with high workloads, an alarm urging maintenance and inspection tends to be issued early. However, it is possible to properly maintain and inspect the traveling gear 20 regardless of the operating environment and usage method of the hydraulic excavator 1. The cumulative load Fc only needs to be reset once after maintenance and inspection of the traveling gear 20.

[0060] In addition, to determine the fatigue of the drive unit 30, an SN diagram (fatigue life) relating the load (stress) S applied to the drive unit 30 and the number of repetitions (time) N can be obtained, and the resultant force Fall of the bolt axial forces F1 and F2 can be set as the load (stress) S, and the cumulative number of repetitions (cumulative time) of the resultant force Fall can be set as the number of repetitions (time) N. Fatigue can then be determined from the SN diagram, and maintenance of the traveling unit 20 can be performed.

[0061] Although the description of the embodiment has been completed above, the aspects of the present invention are not limited to this embodiment. For example, in the above embodiment, the strain gauges 40, 42 are embedded in the bolts 36A, 36B, respectively, but if possible, the strain gauges 40, 42 may be attached to the outer peripheral surfaces of the bolts 36A, 36B, respectively. Also, instead of the strain gauges 40, 42, a washer-type load cell may be used as a washer through which the bolt 36 passes, and the pressure acting on the bolt 36 (correlation value of the bolt axial force) may be detected by the washer-type load cell, and the bolt axial force may be calculated from the pressure.

[0062] It should be noted that the correlation value of the bolt axial force is not limited to the strain detected by the strain gauges 40, 42 or the pressure detected by the washer-type load cell, but the bolt axial force itself may also be included in the correlation value of the bolt axial force, and a sensor capable of directly detecting the bolt axial force may be attached to the bolt 36.

[0063] In the above embodiment, a strain gauge 40 is attached to bolt 36A, which is located at the 6 o'clock position of the hour hand of a clock, i.e., the lowest position in the vertical direction when the traveling device 20 is in contact with the ground, among the multiple bolts 36 provided along the periphery of the circular opening 28, and a strain gauge 42 is attached to bolt 36B, which is located at the 3 / 9 o'clock position of the hour hand of a clock, i.e., the endmost position on one end of the side frame 22 in the longitudinal direction, among the multiple bolts 36 provided along the periphery of the circular opening 28. However, because the bolts 36 are arranged circumferentially around the periphery of the opening 28, strain gauges may also be attached to bolts 36 other than bolts 36A and 36B. For example, additional strain gauges may be attached to bolts 36 located at the 4:30 position of the hour hand of a clock when viewed from the outside of the left traveling device 20 and at the 7:30 position of the hour hand of a clock when viewed from the outside of the right traveling device 20. In this case, the bolt axial force calculated from the strain detected by the added strain gauge may be resolved into vertical and horizontal directions. This increases the bolt axial force to be detected, making it possible to estimate in more detail the track tension, excavation force, and reaction force due to vehicle weight input to the reduction gear 34 and ultimately to the drive unit 30, and thus more accurately determine whether the track tension is excessive or insufficient.

[0064] Furthermore, if the bolt axial force calculated from the strain detected by the strain gauges can be resolved well into the vertical and horizontal directions, it is sufficient to attach strain gauges only to the bolts 36 located, for example, at the 4:30 position when looking at the left-hand traveling unit 20 from the outside, and at the 7:30 position when looking at the right-hand traveling unit 20 from the outside.

[0065] In the above embodiment, an alarm is issued when the bolt axial force F1 exceeds the threshold value F1max, when the bolt axial force F2 is smaller than the threshold value F2min or exceeds the threshold value F2max, or when the resultant force Fall of the bolt axial forces F1 and F2 exceeds the threshold value Fallmax. However, in addition to issuing an alarm, the control device 50 can also perform control to, for example, slow down the traveling speed of the hydraulic excavator 1. By slowing down the traveling speed, it is possible to prevent unnecessary loads from being input to the traveling device 20.

[0066] In the above embodiment, the alarm is displayed on the driver's seat monitor 60, but the form of the alarm is not limited to a character display, and any sound, light, or other device that can attract the operator's attention may be used. In this case, the alarm device that issues the alarm may be a speaker or a light.

[0067] Furthermore, the control device 50 may be provided with a wireless communication function that enables wireless communication with the outside, and the load information, judgment results, alarm issuance status, and the like stored in the memory 56 of the control device 50 may be issued as a report to, for example, a remote manager or maintenance service person using this wireless communication function. By knowing the status of the traveling gear 20 of the hydraulic excavator 1, the manager can give accurate instructions to workers on site even if they are far away, and by knowing the status of the traveling gear 20 of the hydraulic excavator 1, the maintenance service person can, for example, prepare replacement parts in advance, thereby reducing machine downtime.

[0068] Furthermore, in the above embodiment, the construction machine is a hydraulic excavator, but the construction machine is not limited to a hydraulic excavator as long as it is a construction machine equipped with a crawler-type traveling device. [Explanation of symbols]

[0069] 1. Hydraulic excavator (construction machinery) 2 Undercarriage 3 Upper rotating body 4 Work equipment 20 Running gear 21 Truck Frame 22 Side frame 25 idler wheel 20 Running gear 23 Upper roller 24 Lower Roller 26 Tracks 27 Bracket (side frame) 30 Drive unit 31 Drive sprocket (drive wheel) 32 Hydraulic motor 34 Reducer 36 volts 36A 6 o'clock bolt (first bolt) 36B 3 o'clock / 9 o'clock bolt (second bolt) 40, 42 Strain gauge (detection sensor) 50 Control device 54 Arithmetic judgment section 60 Driver's seat monitor (alarm device)

Claims

1. A construction machine having a lower traveling body including a plurality of upper rollers provided at intervals in the longitudinal direction on each of a pair of left and right side frames of a track frame, a plurality of lower rollers provided at intervals in the longitudinal direction on the lower side of the side frames, a drive unit provided with a drive wheel on one end side of the side frames in the longitudinal direction, an idler wheel provided on the other end side of the side frames, and a traveling unit having tracks wound around the drive wheel and the idler wheel, the drive device is fixed to the side frame by a plurality of bolts whose bolt axes are perpendicular to the side surface of the side frame, and the drive device is provided on at least a first bolt located at the lowermost position in the vertical direction when the crawler belt is in a state where it is in contact with the ground, and a second bolt located at the endmost position on the one end side in the longitudinal direction of the side frame, and a plurality of detection sensors that detect correlation values ​​of bolt axial forces acting on the bolts; a control device that determines a state of the traveling device based on detection information from the detection sensor; an alarm device that issues an alarm in response to a signal from the control device, The control device calculates bolt axial forces, including at least a first bolt axial force acting on the first bolt and a second bolt axial force acting on the second bolt, from correlation values ​​of the bolt axial forces detected by the detection sensors, determines the state of the traveling device based on the calculated bolt axial forces, and, if it determines that the traveling device is in an abnormal state, transmits a signal corresponding to the abnormal state to the alarm device.

2. When the first bolt axial force exceeds a first predetermined threshold, the control device determines that the traveling device is in an abnormal state and transmits a signal to the alarm device to warn the user about how to use the construction machine; 2. The construction machine according to claim 1, wherein when the second bolt axial force exceeds a second predetermined threshold, it is determined that the traveling device is in an abnormal state, and a signal is sent to the alarm device to prompt the user to check the tension of the track.

3. 2. The construction machine according to claim 1, wherein the control device calculates at least the square root of the sum of squares of the first bolt axial force and the second bolt axial force, calculates a resultant force of the first bolt axial force and the second bolt axial force from the square root of the sum of squares, and when the resultant force exceeds a predetermined resultant force threshold, determines that the traveling device is in an abnormal state and transmits a signal to the alarm device to prompt improvement of the operating environment of the construction machine.

4. 4. The construction machine according to claim 3, wherein the control device calculates a cumulative load by integrating the resultant force, and when the cumulative load exceeds a predetermined cumulative load threshold, transmits a signal to the alarm device to prompt maintenance and inspection of the traveling device.

5. 2. The construction machine according to claim 1, wherein the detection sensor is a strain gauge that detects strain as a correlated value of the bolt axial force.

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