Irregular operation detection system

Abstract

According to one embodiment of the present invention, an irregular operation detection system (7) for a hydraulic excavator with a replaceable attachment includes: at least one hydraulic pump (2) that supplies hydraulic oil to the attachment or to a hydraulic actuator (5) that drives the attachment; and at least one pressure sensor (91, 92) that measures the discharge pressure of the at least one hydraulic pump (2). Furthermore, the irregular operation detection system (7) includes a processing circuit (81) that determines whether or not an irregular operation has been performed, the determination being made on the basis of the discharge pressure measured by the at least one pressure sensor (91, 92) and a determination condition corresponding to the attachment.

Description

Irregular Operation Detection System

[0001] The present disclosure relates to an irregular operation detection system for a hydraulic excavator.

[0002] Conventionally, a hydraulic excavator with an attachable attachment has been known. For example, attachments include a bucket for excavating earth and sand, a breaker for crushing an object, a grapple for grasping and moving an object, and the like.

[0003] In a hydraulic excavator, the user may use it in a way that is not assumed in the design. For example, Patent Document 1 discloses an abnormal operation detection device that detects an overload operation (abnormal operation) of a hydraulic excavator in order to grasp a usage situation that is likely to lead to a failure.

[0004] Specifically, in the abnormal operation detection device of Patent Document 1, the operating pressure of each of the boom, arm, and bucket is measured by an operating pressure detection means, the joint angle of each joint is estimated based on the cumulative value of the measured operating pressure, and whether an overload operation (abnormal operation) has been performed is determined based on the estimated joint angle of each joint and the variation amount of each operating pressure.

[0005] Japanese Patent Application Laid-Open No. 2009-179975

[0006] In paragraph 0023 of the specification of Patent Document 1, it is described that the operating pressure of the boom is the boom raising operating pressure and the boom lowering operating pressure. Also, from FIG. 5 of Patent Document 1, it is presumed that the operating pressures of the boom, arm, and bucket are the load pressures of the boom cylinder, arm cylinder, and bucket cylinder. That is, the abnormal operation detection device of Patent Document 1 includes at least six pressure sensors.

[0007] Therefore, an object of the present disclosure is to provide an irregular operation detection system that can detect an unexpected irregular operation with a small number of pressure sensors.

[0008] This disclosure provides an irregular operation detection system for a hydraulic excavator with interchangeable attachments, comprising: at least one hydraulic pump that supplies hydraulic fluid to the attachment or to a hydraulic actuator that drives the attachment; at least one pressure sensor that measures the discharge pressure of the at least one hydraulic pump; and a processing circuit that determines whether or not an irregular operation has occurred based on the discharge pressure measured by the at least one pressure sensor and determination conditions corresponding to the attachment.

[0009] According to this disclosure, an irregular operation detection system is provided that can detect unexpected irregular operations with a small number of pressure sensors.

[0010] This is a schematic diagram of a hydraulic system including an irregular operation detection system for a hydraulic excavator according to one embodiment. This is a side view of a hydraulic excavator with a bucket attached. Figures 3A and 3B are graphs showing the change over time of the discharge pressure of the first and second hydraulic pumps when normal operation is performed on a hydraulic excavator with a bucket attached. Figures 4A and 4B are graphs showing the change over time of the discharge pressure of the first and second hydraulic pumps when an irregular operation is performed on the bucket. Figures 5A and 5B are enlarged views of a portion of the period shown in Figures 4A and 4B. This is a diagram for explaining the method of counting pressure surges. Figures 7A and 7B are graphs showing the change over time of the discharge pressure of the first hydraulic pump and the first tilt command pressure in a hydraulic excavator with a breaker attached. Figures 8A and 8B are graphs showing the change over time of the discharge pressure of the second hydraulic pump and the second tilt command pressure in a hydraulic excavator with a breaker attached.

[0011] Figure 1 shows a hydraulic system 10 including an irregular operation detection system 7 according to one embodiment. The irregular operation detection system 7 is for a hydraulic excavator 1 with a replaceable attachment 6, as shown in Figure 2.

[0012] In Figure 2, a bucket 6A for excavating soil is attached to the hydraulic excavator 1 as an attachment 6. Other attachments 6 besides the bucket 6A include a breaker for crushing the material, a grapple for gripping and moving the material, and a skeleton used as a sieve.

[0013] Of the attachments 6 described above, the bucket 6A, grapple, and skeleton are driven by the bucket cylinder 56, which will be described later. On the other hand, the breaker is operated by the supply of hydraulic fluid.

[0014] The hydraulic excavator 1 includes a traveling body 11 and a slewing body 12 that is rotatably supported on the traveling body 11. The slewing body 12 is provided with a cabin 13 including a driver's seat and is connected to a boom 14. An arm 15 is connected to the tip of the boom 14, and a bucket 6A is connected to the tip of the arm 15.

[0015] The hydraulic system 10 includes a first travel motor 51, a second travel motor 52, a slewing motor 53, a boom cylinder 54, an arm cylinder 55, and a bucket cylinder 56 as hydraulic actuators 5. The first travel motor 51 and the second travel motor 52 drive a pair of crawlers of the travel body 11, respectively. The slewing motor 53 rotates the slewing body 12, the boom cylinder 54 raises and lowers the boom 14, the arm cylinder 55 swings the arm 15, and the bucket cylinder 56 swings the bucket 6A.

[0016] Furthermore, the hydraulic system 10 includes at least one hydraulic pump 2 that supplies hydraulic fluid to the hydraulic actuator 5, and a plurality of control valves 4 interposed between the at least one hydraulic pump 2 and the hydraulic actuator 5. The at least one hydraulic pump 2 is also a component of the irregular operation detection system 7.

[0017] In this embodiment, at least one hydraulic pump 2 includes a first hydraulic pump 2A and a second hydraulic pump 2B. In this embodiment, hydraulic fluid is supplied to the boom cylinder 54 and the arm cylinder 55 from both the first hydraulic pump 2A and the second hydraulic pump 2B. However, the hydraulic circuit between the hydraulic pump 2 and the hydraulic actuator 5 can be modified as appropriate, including the number of hydraulic pumps 2.

[0018] Specifically, hydraulic fluid is supplied to the boom cylinder 54 from the first hydraulic pump 2A and the second hydraulic pump 2B via the main boom control valve 44 and the sub-boom control valve 45, and hydraulic fluid is supplied to the arm cylinder 55 from the first hydraulic pump 2A and the second hydraulic pump 2B via the main arm control valve 46 and the sub-arm control valve 47. The first hydraulic pump 2A also supplies hydraulic fluid to the first travel motor 51 via the first travel control valve 41 and to the slewing motor 53 via the slewing control valve 43. The second hydraulic pump 2B supplies hydraulic fluid to the second travel motor 52 via the second travel control valve 42 and to the bucket cylinder 56 via the bucket control valve 48.

[0019] The first travel control valve 41, sub-boom control valve 45, slewing control valve 43, and main arm control valve 46 are connected to the first hydraulic pump 2A by a supply line 31 and to the tank by a tank line 32. The second travel control valve 42, main boom control valve 44, bucket control valve 48, and sub-arm control valve 47 are connected to the second hydraulic pump 2B by a supply line 33 and to the tank by a tank line 34.

[0020] The first travel control valve 41 is connected to the first travel motor 51 by a pair of supply and discharge lines 5a, and the second travel control valve 42 is connected to the second travel motor 52 by a pair of supply and discharge lines 5b. The slewing control valve 43 is connected to the slewing motor 53 by a pair of supply and discharge lines 5c. The main boom control valve 44 is connected to the boom cylinder 54 by a pair of supply and discharge lines 5d, and the sub-boom control valve 45 is connected to the supply and discharge lines 5d by a pair of supply lines 5e. The main arm control valve 46 is connected to the arm cylinder 55 by a pair of supply and discharge lines 5f, and the sub-arm control valve 47 is connected to the supply and discharge lines 5f by a pair of supply lines 5g. The bucket control valve 48 is connected to the bucket cylinder 56 by a pair of supply and discharge lines 5h.

[0021] The cabin 13 described above houses a foot pedal-type first and second travel control device, as well as lever-type slewing, boom, arm, and bucket control devices. These control devices are electrically connected to the control device 8. Note that in Figure 1, some signal lines are omitted for the sake of simplicity.

[0022] The control device 8 includes a processing circuit 81 that controls each control valve 4. Each control valve includes a spool and a drive unit that receives a command current from the processing circuit 81 and drives the spool. For example, the drive unit may include a pair of electromagnetic proportional valves that output secondary pressures acting on the spool in opposite directions, or it may be a linear motion mechanism including an electric motor and a ball screw, etc., connected to the spool.

[0023] When any of the operating devices is operated, the processing circuit 81 increases the opening area of ​​the corresponding control valve 4 so that the flow rate of hydraulic fluid supplied to the corresponding hydraulic actuator 5 increases as the amount of operation increases.

[0024] However, each control valve 4 does not necessarily have to be controlled by the processing circuit 81. For example, if the operating device is a pilot-operated valve that outputs a pilot pressure corresponding to the amount of operation, each control valve 4 may include a pair of pilot ports instead of a drive unit that receives a command current, and a pilot-operated valve may be connected to the pair of pilot ports.

[0025] Furthermore, in this embodiment, the second hydraulic pump 2B is also connected to the optional control valve 49 via the supply line 33. When a hydraulically driven attachment 6B, which operates by the supply of hydraulic fluid such as a breaker, is attached to the hydraulic excavator 1 as an attachment 6, the optional control valve 49 is connected to the hydraulically driven attachment 6B via the optional line 5i. In other words, the second hydraulic pump 2B supplies hydraulic fluid to the hydraulically driven attachment 6B via the optional control valve 49. The optional control valve 49 is also controlled by the processing circuit 81.

[0026] The first hydraulic pump 2A and the second hydraulic pump 2B described above are variable displacement pumps with adjustable tilt angles. For example, the first hydraulic pump 2A and the second hydraulic pump 2B are axial piston pumps such as swashplate pumps and oblique shaft pumps.

[0027] The tilt angle of the first hydraulic pump 2A is changed by the first regulator 21, which receives the first tilt command pressure Pt1, and the tilt angle of the second hydraulic pump 2B is changed by the second regulator 23, which receives the second tilt command pressure Pt2. In other words, the first tilt command pressure Pt1 is supplied to the first regulator 21 through the first command pressure line 22, and the second tilt command pressure Pt2 is supplied to the second regulator 23 through the second command pressure line 24.

[0028] For example, if the first hydraulic pump 2A is a swashplate pump, the first regulator 21 may include a servo piston connected to the swashplate of the first hydraulic pump 2A. Similarly, if the second hydraulic pump 2B is a swashplate pump, the second regulator 23 may include a servo piston connected to the swashplate of the second hydraulic pump 2B.

[0029] For example, the first command pressure line 22 is connected to a first electromagnetic proportional valve that outputs a first tilt command pressure Pt1 as a secondary pressure, and the second command pressure line 24 is connected to a second electromagnetic proportional valve that outputs a second tilt command pressure Pt2 as a secondary pressure. In this case, the first and second electromagnetic proportional valves are controlled by a processing circuit 81. Specifically, when either of the operating devices is operated, the processing circuit 81 controls one or both of the first and second electromagnetic proportional valves so that the discharge flow rate of one or both of the first and second hydraulic pumps 2A and 2B, which supply hydraulic fluid to the corresponding hydraulic actuator 5, increases as the amount of operation increases.

[0030] However, if the discharge flow rate of the first hydraulic pump 2A is controlled by a negative control method, the first command pressure line 22 may be connected to the downstream portion of the control valve 4 in the center bypass line, which branches off from the supply line 31 and passes through the control valve 4 to which the supply line 31 is connected. Alternatively, if the discharge flow rate of the first hydraulic pump 2A is controlled by a load sensing method, the first command pressure line 22 may be connected to the maximum load pressure detection line.

[0031] Similarly, if the discharge flow rate of the second hydraulic pump 2B is controlled by a negative control method, the second command pressure line 24 may be connected to the downstream portion of the control valve 4 in the center bypass line, which branches off from the supply line 33 and passes through the control valve 4 to which the supply line 33 is connected. Alternatively, if the discharge flow rate of the second hydraulic pump 2B is controlled by a load sensing method, the second command pressure line 24 may be connected to the maximum load pressure detection line.

[0032] In addition to the processing circuit 81 described above, the control device 8 includes a user interface 82 having a display screen that functions as an input and a display. The user interface 82 is, for example, a touchscreen. However, instead of the control device 8 including the user interface 82, the input and display may be electrically connected to the control device 8.

[0033] With respect to the control device 8, the functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, dedicated processors, integrated circuits, ASICs (Application Specific Integrated Circuits), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuits. In this disclosure, a circuit, unit, or means is hardware that performs the enumerated functions, or hardware programmed to perform the enumerated functions. The hardware may be hardware disclosed herein, or other known hardware that is programmed or configured to perform the enumerated functions. If the hardware is a processor, which is considered a type of circuit, then the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or the processor.

[0034] The control device 8 is electrically connected to both the first main pressure sensor 91 and the second main pressure sensor 92. The first main pressure sensor 91 is installed in the supply line 31 and measures the discharge pressure Pd1 of the first hydraulic pump 2A. The second main pressure sensor 92 is installed in the supply line 33 and measures the discharge pressure Pd2 of the second hydraulic pump 2B.

[0035] The processing circuit 81 determines whether an irregular operation has occurred based on the discharge pressures Pd1 and Pd2 measured by the first main pressure sensor 91 and the second main pressure sensor 92, and the determination conditions corresponding to the attachment 6. In this embodiment, the processing circuit 81 continuously determines whether an irregular operation has occurred while the hydraulic excavator 1 is in operation. This makes it possible to determine whether an irregular operation has occurred in real time.

[0036] Furthermore, in this embodiment, the control device 8 is electrically connected to both the first auxiliary pressure sensor 93 and the second auxiliary pressure sensor 94. The first auxiliary pressure sensor 93 is provided on the first command pressure line 22 and measures the first tilt command pressure Pt1 received by the first regulator 21. The second auxiliary pressure sensor 94 is provided on the second command pressure line 24 and measures the second tilt command pressure Pt2 received by the second regulator 23.

[0037] Therefore, the processing circuit 81 may also determine whether an irregular operation has been performed based on the discharge pressures Pd1 and Pd2 measured by the first main pressure sensor 91 and the second main pressure sensor 92, the first tilt command pressure Pt1 and the second tilt command pressure Pt2 measured by the first auxiliary pressure sensor 93 and the second auxiliary pressure sensor 94, and determination conditions corresponding to the attachment 6.

[0038] In other words, the first main pressure sensor 91, the second main pressure sensor 92, the first secondary pressure sensor 93, and the second secondary pressure sensor 94, together with the first hydraulic pump 2A, the second hydraulic pump 2B, and the control device 8, constitute the irregular operation detection system 7.

[0039] Figures 3A and 3B show the changes over time of the discharge pressure Pd1 of the first hydraulic pump 2A and the discharge pressure Pd2 of the second hydraulic pump 2B when normal operation is performed on the hydraulic excavator 1 with the bucket 6A attached. Figures 4A and 4B also show the changes over time of the discharge pressure Pd1 of the first hydraulic pump 2A and the discharge pressure Pd2 of the second hydraulic pump 2B when irregular operation is performed on the bucket 6A.

[0040] A comparison of Figure 3B and Figure 4B shows that when irregular operations are performed, the frequency of pressure surges is higher and the pressure surge values ​​are higher compared to when normal operations are performed. Figures 5A and 5B are enlarged views of a portion of the period shown in Figures 4A and 4B. A pressure surge is a large rise in pressure over a very short period of time, as shown in Figure 5B.

[0041] In this embodiment, the processing circuit 81 identifies the type of attachment 6 attached to the hydraulic excavator 1 from the pressure waveform of the discharge pressure Pd1 measured by the first main pressure sensor 91 and the pressure waveform of the discharge pressure Pd2 measured by the second main pressure sensor 92. For example, the processing circuit 81 calculates the pressure surge occurrence period from the pressure waveform of the discharge pressure Pd2 of the second hydraulic pump 2B that supplies hydraulic fluid to the bucket cylinder 56, which is measured by the second main pressure sensor 92. If the calculated pressure surge occurrence period is less than a predetermined frequency Fa, it is determined that the attachment 6 attached to the hydraulic excavator 1 is a bucket 6A. For example, the predetermined frequency Fa is 1 Hz.

[0042] The processing circuit 81 first determines whether the attachment 6 attached to the hydraulic excavator 1 is a bucket 6A using the method described above. If it is not a bucket 6A, the next step is to identify the type of attachment 6 attached to the hydraulic excavator 1 from the pressure waveform of the discharge pressure Pd1 measured by the first main pressure sensor 91 and the pressure waveform of the discharge pressure Pd2 measured by the second main pressure sensor 92.

[0043] As shown in Figure 6, the processing circuit 81 determines that a pressure surge has occurred once if the discharge pressure rises above a first threshold α, rises above a second threshold β, and then falls below a third threshold γ in a continuous sequence, and the time T from when the discharge pressure rises above the first threshold α until it falls below the third threshold γ is within a predetermined time range Rt. For example, the first threshold α is 25 MPa and the second threshold β is 35 MPa. The third threshold γ may be equal to the first threshold α, or it may be greater than or less than the first threshold α. The predetermined time range Rt is, for example, 0.001 seconds or more and 0.3 seconds or less.

[0044] The determination criterion that the calculated generation period of the pressure surge is less than the predetermined frequency Fa may be used as the determination criterion for the attachment 6 (for example, grapple) with an operation similar to that of the bucket 6A. Further, when the pressure waveform of the discharge pressure Pd2 of the second hydraulic pump 2B connected to the option control valve 49 has a characteristic falling shape, the processing circuit 81 may determine that the attachment 6 is a breaker. Furthermore, when both the rising shape of the pressure waveform of the discharge pressure Pd1 of the first hydraulic pump 2A and the rising shape of the pressure waveform of the discharge pressure Pd2 of the second hydraulic pump 2B have characteristics, the processing circuit 81 may determine that the attachment 6 is a skeleton. Note that the determination method for the skeleton is also applicable when the number of hydraulic pumps 2 is one.

[0045] However, the type of the attachment 6 attached to the hydraulic excavator 1 may be input to the processing circuit 81 by the user via the user interface 82.

[0046] Regarding the determination of the irregular operation described above, when the bucket 6A is attached to the hydraulic excavator 1 as the attachment 6, the processing circuit 81 calculates the generation frequency of the pressure surge in the first hydraulic pump 2A from the pressure waveform of the discharge pressure Pd1 measured by the first main pressure sensor 91, and calculates the generation frequency of the pressure surge in the second hydraulic pump 2B from the pressure waveform of the discharge pressure Pd2 measured by the second main pressure sensor 92. When the calculated generation frequency of the pressure surge satisfies the determination condition for the bucket, it is determined that an irregular operation has been performed.

[0047] As the determination condition for the bucket, for example, the generation frequency of the pressure surge in the second hydraulic pump 2B that supplies hydraulic oil to the bucket cylinder 56 (the number of occurrences of the pressure surge per unit time (for example, 10 seconds)) is within a predetermined number range (for example, 3 or more and 100 or less), and the generation frequency of the pressure surge continues within the predetermined number range for a plurality of times (for example, 3 or more and 100 or less).

[0048] On the other hand, when a breaker is attached to the hydraulic excavator 1 as an attachment 6, not only the pressure waveform of the discharge pressure Pd2 of the second hydraulic pump 2B that supplies hydraulic oil to the breaker as shown in FIG. 8A, but also the second tilting command pressure Pt2 received by the second regulator 23 as shown in FIG. 8B is preferably used. For this reason, the processing circuit 81 determines whether an irregular operation has been performed based on the discharge pressure Pd2 of the second hydraulic pump 2B, the second tilting command pressure Pt2, and a determination condition corresponding to the attachment 6. As shown in FIGS. 7A and 7B, in an irregular operation, there is a possibility that some operation may be performed on the hydraulic actuator 5 to which hydraulic oil is supplied from the first hydraulic pump 2A.

[0049] Specifically, the processing circuit 81 determines that an irregular operation has been performed when the following breaker determination conditions are satisfied. The breaker determination conditions are that the maximum value of the discharge pressure Pd2 of the second hydraulic pump 2B in a unit time (for example, 1 second or more and 5 seconds or less) deviates from a predetermined range (for example, 20 MPa or more and 30 MPa or less), and the fluctuation range of the second tilting command pressure Pt2 in the same unit time deviates from a predetermined range (for example, 0.5 MPa).

[0050] Further, as a skeleton determination condition for determining that an irregular operation has been performed when the attachment 6 is a skeleton, for example, the occurrence frequency of a pressure surge in the second hydraulic pump 2B that supplies hydraulic oil to the bucket cylinder 56 (the number of occurrences of pressure surges per unit time (for example, 10 seconds)) is within a predetermined number range (for example, 30 times or more and 100 times or less), and the occurrence frequency of the pressure surge continues within the predetermined number range for a plurality of times (for example, 6 times or more and 100 times or less).

[0051] Finally, the processing circuit 81 displays the determination result as to whether an irregular operation has been performed on the display screen of the user interface 82.

[0052] The irregular operation detection system 7 with the configuration described above provides the following benefits. Irregular operations can be anticipated to some extent for each attachment 6. For example, if the attachment 6 is a bucket 6A, an irregular operation would be repeatedly and forcefully slamming the back of the bucket 6A against the ground, and if the attachment 6 is a breaker, it would be moving the tip of the breaker in a way that peels off the surface of the object. In other words, when an irregular operation occurs, a phenomenon specific to the attachment 6 appears in the pressure waveform of the discharge pressure Pd1 of the first hydraulic pump 2A or the discharge pressure Pd2 of the second hydraulic pump 2B. Therefore, by using judgment conditions corresponding to the attachment 6 for the discharge pressure Pd1 of the first hydraulic pump 2A or the discharge pressure Pd2 of the second hydraulic pump 2B, irregular operations can be detected with a small number of pressure sensors. Moreover, irregular operations can be detected without needing to understand the operation of the hydraulic excavator 1 or damage to the hydraulic excavator 1 itself.

[0053] Furthermore, in this embodiment, the processing circuit 81 identifies the type of attachment 6 attached to the hydraulic excavator 1 from the pressure waveform of the discharge pressure Pd1 measured by the first main pressure sensor 91 and the pressure waveform of the discharge pressure Pd2 measured by the second main pressure sensor 92. Thus, the processing circuit 81 can independently acquire information on which attachment 6 is currently attached to the hydraulic excavator 1. In particular, in this embodiment, the processing circuit 81 can independently acquire information that a bucket 6A is currently attached as the attachment 6 to the hydraulic excavator 1 based on the pressure surge generation cycle.

[0054] Furthermore, in this embodiment, since the irregular operation detection system 7 includes a first auxiliary pressure sensor 93 and a second auxiliary pressure sensor 94, by using the first tilt command pressure Pt1 and the second tilt command pressure Pt2, it is possible to detect irregular operations that are difficult to detect using only the discharge pressure Pd1 of the first hydraulic pump 2A and the discharge pressure Pd2 of the second hydraulic pump 2B.

[0055] <Modifications> This disclosure is not limited to the embodiments described above, and various modifications are possible without departing from the gist of this disclosure.

[0056] <Summary> In a first aspect, the present disclosure provides an irregular operation detection system for a hydraulic excavator with interchangeable attachments, comprising: at least one hydraulic pump that supplies hydraulic fluid to the attachment or to a hydraulic actuator that drives the attachment; at least one pressure sensor that measures the discharge pressure of the at least one hydraulic pump; and a processing circuit that determines whether or not an irregular operation has occurred based on the discharge pressure measured by the at least one pressure sensor and determination conditions corresponding to the attachment.

[0057] Irregular operations can be anticipated to some extent for each attachment. For example, if the attachment is a bucket, an irregular operation would be repeatedly and forcefully slamming the back of the bucket against the ground; if the attachment is a breaker, it would be moving the tip of the breaker in a way that peels off the surface of the object. In other words, when an irregular operation occurs, a phenomenon specific to the attachment appears in the pressure waveform of the hydraulic pump's discharge pressure. Therefore, by using judgment conditions appropriate to the attachment for the hydraulic pump's discharge pressure, irregular operations can be detected with a small number of pressure sensors. Moreover, irregular operations can be detected without needing to understand the operation of the hydraulic excavator or damage to the excavator itself.

[0058] In a second embodiment, in the first embodiment, the processing circuit may calculate the pressure surge occurrence period from the pressure waveform of the discharge pressure measured by the at least one pressure sensor, and determine that the attachment attached to the hydraulic excavator is a bucket if the calculated pressure surge occurrence period is less than a predetermined frequency. With this configuration, the processing circuit can independently acquire information that a bucket is currently attached as an attachment to the hydraulic excavator.

[0059] In a third embodiment, in the first or second embodiment, the processing circuit may identify the type of attachment mounted on the hydraulic excavator from the pressure waveform of the discharge pressure measured by the at least one pressure sensor. With this configuration, the processing circuit can independently acquire information on which attachment is currently mounted on the hydraulic excavator.

[0060] In a fourth embodiment, in any of the first to third embodiments, for example, if a bucket is attached as the attachment to the hydraulic excavator, the processing circuit may calculate the frequency of pressure surges from the pressure waveform of the discharge pressure measured by the at least one pressure sensor, and determine that the irregular operation has been performed if the calculated frequency of pressure surges satisfies the bucket determination conditions.

[0061] In a fifth embodiment, in any of the first to fourth embodiments, the at least one hydraulic pump is a variable displacement pump whose tilt angle is changed by a regulator that receives a tilt command pressure, the at least one pressure sensor is a main pressure sensor, the irregular operation detection system further comprises a secondary pressure sensor that measures the tilt command pressure, and the processing circuit may determine whether or not the irregular operation has been performed based on the discharge pressure measured by the at least one main pressure sensor, the tilt command pressure measured by the secondary pressure sensor, and a determination condition corresponding to the attachment. With this configuration, by using the tilt command pressure, it is possible to detect irregular operations that are difficult to detect by the discharge pressure of the hydraulic pump alone.

[0062] In a sixth embodiment, in any of the first to fifth embodiments, the processing circuit may continuously determine whether or not the irregular operation has been performed while the hydraulic excavator is in operation. With this configuration, it is possible to determine in real time whether or not the irregular operation has been performed.

[0063] In a seventh embodiment, in any of the first to sixth embodiments, for example, the at least one hydraulic pump may include a plurality of hydraulic pumps, and the at least one pressure sensor may include a plurality of pressure sensors.

[0064] 1 Hydraulic excavator, 2, 2A, 2B Hydraulic pump, 6 Attachments, 6A Bucket, 6B Hydraulically driven attachment, 7 Irregular operation detection system, 8 Control device, 81 Processing circuit, 91, 92 Main pressure sensors, 93, 94 Sub-pressure sensors

Claims

1. An irregular operation detection system for a hydraulic excavator with interchangeable attachments, comprising: at least one hydraulic pump that supplies hydraulic fluid to the attachment or to a hydraulic actuator that drives the attachment; at least one pressure sensor that measures the discharge pressure of the at least one hydraulic pump; and a processing circuit that determines whether or not an irregular operation has occurred based on the discharge pressure measured by the at least one pressure sensor and determination conditions corresponding to the attachment.

2. The processing circuit calculates the period of occurrence of a pressure surge from the pressure waveform of the discharge pressure measured by the at least one pressure sensor, and determines that the attachment attached to the hydraulic excavator is a bucket when the calculated period of occurrence of the pressure surge is less than a predetermined frequency, as described in claim 1.

3. The irregular operation detection system according to claim 1 or 2, wherein the processing circuit identifies the type of attachment mounted on the hydraulic excavator from the pressure waveform of the discharge pressure measured by the at least one pressure sensor.

4. When a bucket is attached to the hydraulic excavator as the attachment, the processing circuit calculates the frequency of pressure surges from the pressure waveform of the discharge pressure measured by the at least one pressure sensor, and determines that the irregular operation has been performed when the calculated frequency of pressure surges satisfies the bucket determination conditions, as described in claim 1 or 2.

5. The irregular operation detection system according to claim 1 or 2, wherein the at least one hydraulic pump is a variable displacement pump whose tilt angle is changed by a regulator that receives a tilt command pressure, the at least one pressure sensor is a main pressure sensor, and the system further comprises a secondary pressure sensor that measures the tilt command pressure, and the processing circuit determines whether or not the irregular operation has been performed based on the discharge pressure measured by the at least one main pressure sensor, the tilt command pressure measured by the secondary pressure sensor, and a determination condition corresponding to the attachment.

6. The irregular operation detection system according to claim 1 or 2, wherein the processing circuit continuously determines whether or not the irregular operation has been performed while the hydraulic excavator is in operation.

7. The irregular operation detection system according to claim 1 or 2, wherein the at least one hydraulic pump comprises a plurality of hydraulic pumps, and the at least one pressure sensor comprises a plurality of pressure sensors.

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