Filter abnormality detection device

Abstract

To provide a filter abnormality detection device capable of accurately detecting abnormality related to a return filter.SOLUTION: An abnormality detection device 5 (filter abnormality detection device) for detecting a filter abnormality that is an abnormality related to a return filter 42 through which return oil from an actuator 30,31 in a construction machine 1 passes, the abnormality detection device 5 comprising: The control unit 7 includes the first determination section 72 configured to determine whether or not the return fluid is in the predetermined state in which the return fluid has a pressure higher than the predetermined pressure, and the second determination section 73 configured to determine that there is a filter abnormality when the first determination section 72 determines that the return fluid is in the predetermined state and when the differential pressure measured by the differential pressure measurement section 63 is less than the predetermined differential pressure threshold.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a filter abnormality detection device, and more particularly to a filter abnormality detection device that detects an abnormality in a return filter through which return oil from an actuator in a construction machine passes. [Background technology]

[0002] Conventionally, there has been known a device for detecting an abnormality in a filter that detects whether the filter is a non-genuine product that is inferior to the genuine product (see, for example, Patent Document 1). The abnormality detection device described in Patent Document 1 determines that the fuel filter is a non-genuine product when the fuel pressure downstream of the fuel filter is a negative pressure that is closer to atmospheric pressure than normal negative pressure, and specifically includes a fuel chamber that communicates with a flow path downstream of the fuel filter, and a level switch that turns ON as the fuel level in the fuel chamber rises when the fuel pressure in the flow path becomes closer to atmospheric pressure than normal negative pressure, and is configured to determine that the fuel filter is a non-genuine product when the switch turns ON under predetermined conditions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-63856 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional abnormality detection device, the ON / OFF of the switch that serves as the criterion for determining whether the fuel filter is a non-genuine product depends on the fuel level in the fuel chamber, and therefore there is a concern that the determination result will vary due to, for example, rippling of the fuel, and therefore the accuracy of the abnormality detection will decrease. Furthermore, even if a pressure sensor or the like is used instead of the switch as a means for determining whether the fuel pressure downstream of the fuel filter is a negative pressure closer to atmospheric pressure than normal negative pressure, it is difficult to ensure the accuracy of the abnormality detection unless a high-precision, expensive pressure sensor or the like that can measure pressure in a low-pressure region (a region close to atmospheric pressure) is used.

[0005] The present invention was made with the above in mind when developing technology for detecting abnormalities in a return filter through which return oil from an actuator in a construction machine passes, and aims to provide a filter abnormality detection device that can accurately detect abnormalities in the return filter. [Means for solving the problem]

[0006] In order to achieve the above object, the filter abnormality detection device of the present invention is configured as follows: The filter abnormality detection device of the present invention is a filter abnormality detection device that detects a filter abnormality, which is an abnormality related to a return filter through which return oil from an actuator in a construction machine passes, and includes a differential pressure measurement unit that measures the differential pressure before and after the return filter, and a control unit. The control unit has a first determination unit that determines whether the return oil is in a predetermined state in which the pressure is higher than a predetermined pressure, and a second determination unit that determines that the filter abnormality exists when the first determination unit determines that the return oil is in the predetermined state and when the differential pressure measured by the differential pressure measurement unit is less than a predetermined differential pressure threshold.

[0007] According to the above configuration, first, the first determination unit determines whether or not the return oil is in a predetermined state where the pressure is higher than a predetermined pressure. This first determination unit can achieve the following.

[0008] When the return oil is in the above-mentioned predetermined state, that is, when the pressure of the return oil is higher than the predetermined pressure, it is expected that the pressure on the return filter will be higher than when it is not in that state. For example, when the return oil is in the above-mentioned predetermined state, if the return filter is a genuine, good-quality product and properly installed (no filter abnormalities), even if the return filter is new and free of foreign matter, which allows the return oil to pass easily, the pressure on the return filter will be higher than when the return oil is not in the above-mentioned predetermined state, and the differential pressure before and after the return filter (filter differential pressure) will be higher.

[0009] On the other hand, if the return filter is a non-genuine product, for example, one with a coarser mesh than the genuine product, a defective product, or improperly installed (filter malfunction), the pressure on the return filter will not be as high as when the return oil is not in the predetermined state, and the filter differential pressure will not be as high. Therefore, when the return oil is in the predetermined state (a state in which the pressure is higher than the predetermined pressure), the difference between the filter differential pressure when there is no filter malfunction and the filter differential pressure when there is a filter malfunction will be more significant than when there is not. This makes it easier to determine whether there is a filter malfunction based on the filter differential pressure. In other words, the first determination unit determines whether the return oil is in the predetermined state, making it possible to determine whether there is a filter malfunction based on the filter differential pressure.

[0010] Subsequently, the second determination unit determines whether or not there is a filter abnormality.

[0011] Specifically, the second determination unit determines that a filter abnormality exists when the first determination unit determines that the return oil is in the predetermined state and the differential pressure (filter differential pressure) measured by the differential pressure measurement unit is less than a predetermined differential pressure threshold. As described above, the determination by the second determination unit includes determining whether the filter differential pressure measured by the differential pressure measurement unit is less than a predetermined differential pressure threshold (filter differential pressure determination step), based on the fact that the filter differential pressure would not be significantly higher if a filter abnormality exists. This filter differential pressure determination step is executed when the first determination unit determines that the return oil is in the predetermined state, i.e., when it is easy to determine whether a filter abnormality exists based on the filter differential pressure. This makes it possible to accurately determine whether a filter abnormality exists based on the filter differential pressure measured by the differential pressure measurement unit. In this way, the filter abnormality detection device according to the present invention can accurately detect abnormalities related to the return filter.

[0012] Furthermore, as a secondary effect, as described above, the filter differential pressure determination step is executed when it is easy to determine whether or not there is a filter abnormality based on the filter differential pressure, so it becomes possible to accurately determine whether or not there is a filter abnormality without using a high-precision, expensive differential pressure sensor, etc., and therefore the manufacturing costs of the filter abnormality detection device can be reduced.

[0013] The above filter abnormality detection device may further include an operation amount measuring unit that measures an operation amount of the actuator, and the first determination unit may determine whether the return oil is in the specified state based on the operation amount measured by the operation amount measuring unit.

[0014] As the operation amount of the actuator changes, the flow rate of the return oil from the actuator changes, and therefore the pressure of the return oil changes. Based on this, with the above configuration, it is possible to easily determine whether the return oil is in the predetermined state based on the operation amount measured by the operation amount measuring unit.

[0015] The above-mentioned filter abnormality detection device may further include a temperature measurement unit that measures the temperature of the return oil, and the first judgment unit may judge that the return oil is in the predetermined state when the temperature measured by the temperature measurement unit is equal to or lower than a predetermined temperature threshold.

[0016] The temperature of the return oil is measured by the temperature measuring unit, and the viscosity of the return oil increases as the temperature of the return oil decreases, which increases the pressure of the return oil.

[0017] The filter abnormality detection device may further include a rotation speed measurement unit that measures the rotation speed of an engine that is a driving source of a pump that supplies hydraulic oil to the actuator, and the first determination unit may determine that the return oil is in the predetermined state when the rotation speed measured by the rotation speed measurement unit is equal to or greater than a predetermined rotation speed threshold.

[0018] As the rotation speed of the engine, which is the drive source of the pump that supplies hydraulic oil to the actuator, increases, the flow rate of return oil from the actuator increases, and the pressure of the return oil increases. Based on this, with the above configuration, it is possible to easily determine whether the return oil is in the predetermined state based on the rotation speed measured by the rotation speed measurement unit.

[0019] The above-mentioned filter abnormality detection device may include an operation amount measuring unit that measures the operation amount of the actuator, a temperature measuring unit that measures the temperature of the return oil, and a rotation speed measuring unit that measures the rotation speed of an engine that is the driving source of a pump that supplies hydraulic oil to the actuator, and the first determination unit may determine whether the return oil is in the specified state based on the operation amount measured by the operation amount measuring unit, the temperature measured by the temperature measuring unit, and the rotation speed measured by the rotation speed measuring unit.

[0020] According to the above configuration, multiple determinations are made based on the operation amount measured by the operation amount measuring unit, the temperature measured by the temperature measuring unit, and the rotation speed measured by the rotation speed measuring unit, thereby making it possible to more accurately determine whether the return oil is in the above-mentioned specified state.

[0021] In the above-mentioned filter abnormality detection device, the actuator may be composed of a hydraulic cylinder, and the first determination unit may determine that the return oil is in the predetermined state when the operation amount measured by the operation amount measurement unit is equal to or greater than a predetermined operation amount threshold during a contraction operation of the hydraulic cylinder.

[0022] When the actuator is a hydraulic cylinder, the flow rate of the return oil tends to be higher during a retraction operation of the hydraulic cylinder compared to a retraction operation of the hydraulic cylinder due to the difference in cross-sectional area between the rod-side oil chamber on the supply side, where hydraulic oil is supplied, and the head-side oil chamber on the discharge side, where return oil is discharged, and therefore the pressure of the return oil tends to be higher during a retraction operation of the hydraulic cylinder compared to a retraction operation of the hydraulic cylinder. Based on this, according to the above configuration, when the return oil has a particularly high pressure during a retraction operation of the hydraulic cylinder, that is, when it is easier to determine whether or not there is a filter abnormality based on the filter differential pressure, the second determination unit executes the filter differential pressure determination step, thereby making it possible to more accurately determine whether or not there is a filter abnormality.

[0023] In the above-described filter abnormality detection device, the second determination unit may refer to a threshold value table that associates the type of operation of the actuator with the predetermined differential pressure threshold value for that type, and determine that the filter abnormality exists when the differential pressure measured by the differential pressure measurement unit is less than the predetermined differential pressure threshold value that corresponds to the type of operation of the actuator in the threshold value table.

[0024] The flow rate of return oil discharged from the actuator may vary depending on the type of actuator operation. For example, if the actuator is a hydraulic cylinder, as described above, the flow rate of return oil tends to be higher when the hydraulic cylinder is retracted compared to when it is extended. Conversely, when the hydraulic cylinder is extended, the flow rate of return oil tends to be lower compared to when it is retracted due to the difference in cross-sectional area between the head-side oil chamber on the supply side and the rod-side oil chamber on the discharge side. As described above, when the flow rate of return oil varies depending on the type of actuator operation, the pressure of the return oil differs, and therefore the range of filter differential pressure when a filter abnormality exists also differs depending on the type of actuator operation. Based on this, according to the above configuration, a predetermined differential pressure threshold corresponding to the type of actuator operation is used in the filter differential pressure determination step, making it possible to more accurately determine whether or not a filter abnormality exists depending on the type of actuator operation.

[0025] In the filter abnormality detection device, the control unit may include a clogging determination unit that determines that the return filter is clogged when the differential pressure measured by the differential pressure measurement unit is equal to or greater than the predetermined clogging threshold. With this configuration, clogging of the return filter can be detected.

[0026] In the above-described filter abnormality detection device, the actuator may be configured as a hydraulic cylinder, and may include an alarm unit that issues an alarm to prompt the hydraulic cylinder to contract when the temperature measured by the temperature measurement unit falls below a predetermined temperature threshold for the first time after the return filter has been replaced, so that the operation amount measured by the operation amount measurement unit becomes equal to or greater than a predetermined operation amount threshold and the rotation speed measured by the rotation speed measurement unit becomes equal to or greater than a predetermined rotation speed threshold.

[0027] According to the above configuration, the return oil can be brought to the predetermined state quickly after the return filter is replaced, and therefore the second determination unit can quickly determine whether or not there is a filter abnormality. In this way, an abnormality related to the return filter can be detected quickly after the return filter is replaced. [Effects of the Invention]

[0028] As described above, according to the present invention, an abnormality in the return filter can be detected with high accuracy. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a schematic side view of a construction machine according to a first embodiment, as viewed from the left. [Figure 2] FIG. 2 is a block diagram showing a hydraulic circuit and the like of the construction machine of FIG. [Figure 3] FIG. 3 is a flowchart illustrating an example of a procedure of processing by the control unit of the anomaly detection device. [Figure 4] FIG. 4 is a flowchart illustrating an example of a procedure of processing by the first determination unit. [Figure 5] FIG. 5 is a diagram illustrating an example of the threshold table. [Figure 6] FIG. 6 is a graph showing an example of the execution timing of processing by the control unit of the anomaly detection device. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Unless otherwise specified, the direction in which an operator facing forward while sitting in the driver's seat 14 of the construction machine 1 faces will be referred to as "forward," the direction opposite to forward will be referred to as "rear," the side to the left of the operator facing forward while sitting in the driver's seat 14 will be referred to as "left," and the direction opposite to left will be referred to as "right." In the drawings, the left is indicated by the symbol L and the right is indicated by the symbol R.

[0031] (Configuration of construction machinery) 1 is a schematic side view of a construction machine 1 in embodiment 1, seen from the left. First, the configuration of the construction machine 1 in one embodiment of the present invention will be described.

[0032] As shown in Fig. 1, the construction machine 1 is, for example, a hydraulic excavator, and includes a lower traveling body 10, an upper rotating body 11, and an attachment 2. Each of these components will be described below in order.

[0033] The undercarriage 10 is a part that causes the construction machine 1 to travel (forward and backward), turn, etc. The undercarriage 10 is, for example, a crawler type, and is driven by an actuator 30 that is constituted by a hydraulic motor.

[0034] The upper rotating body 11 is rotatably mounted on the undercarriage 10 and has a box-shaped operator's cab 12 and a machine room 13 located behind the operator's cab 12. Inside the operator's cab 12, there is a driver's seat 14 located in the center of the floor and an operation unit 15 that can be operated by an operator sitting in the driver's seat 14. The operation unit 15 is located in front of the driver's seat 14 and includes a travel lever 15a for moving the undercarriage 10, operation levers 15b for moving the attachment 2, located on both the left and right sides of the driver's seat 14, and a remote control valve 15c, not shown in FIG. 1, that outputs pilot pressure to the hydraulic system in response to operation of the travel lever 15a and operation lever 15b by the operator. The machine room 13, neither of which is shown in FIG. 1, houses an engine 16 that is the power source of the construction machine 1 and a pump 17 that is driven by the engine 16 and supplies hydraulic oil to the hydraulic system.

[0035] The attachment 2 is a part that performs work such as excavation work, and includes, for example, a boom 20, an arm 21, and a bucket 22. The boom 20 is attached to the upper rotating body 11 so that it can be raised and lowered (it can rotate about an axis extending in the left-right direction, the same applies below), the arm 21 is attached so that it can be raised and lowered relative to the boom 20, and the bucket 22 is attached so that it can be raised and lowered relative to the arm 21. The boom 20, arm 21, and bucket 22 perform their raising and lowering operations by being driven by actuators 31A to 31C, each of which is composed of a hydraulic cylinder. Hereinafter, matters and structures common to the actuators 31A to 31C will be described and illustrated using the common reference numeral 31.

[0036] Fig. 2 is a block diagram showing the hydraulic circuit and the like of the construction machine 1 of Fig. 1. As shown in Fig. 2, in addition to the above configuration, the construction machine 1 is equipped with a tank 40 that stores hydraulic oil for operating the actuators 30, 31, a control valve 41 that supplies the hydraulic oil supplied from the tank 40 by the pump 17 to the actuators 30, 31, and a return filter 42 through which the hydraulic oil (return oil) returning from the actuators 30, 31 to the tank 40 passes and which filters the return oil (removes foreign matter mixed in with the return oil). The actuators 30, 31 are operated by the hydraulic oil supplied from the control valve 41 in accordance with the pilot pressure output from the remote control valve 15c of the operation unit 15. The pump 17 and the control valve 41 are provided in each oil passage from the tank 40 to the actuators 30, 31.

[0037] Incidentally, if an abnormality occurs in the return filter 42 (such as an abnormality that the return filter 42 is a non-genuine product, an abnormality that the return filter 42 is a defective product, or an abnormality that the return filter 42 is not properly assembled (misassembled), hereinafter referred to simply as a "filter abnormality"), the desired filtering performance cannot be obtained, and problems arise in that foreign matter cannot be sufficiently removed from the return oil. In order to detect such filter abnormalities, as shown in FIG. 2, the construction machine 1 is provided with an abnormality detection device 5 (filter abnormality detection device) that detects filter abnormalities. The configuration of the abnormality detection device 5 will be described in detail below.

[0038] (Configuration of anomaly detection device) 2, the abnormality detection device 5 includes a measurement unit 6, a control unit 7, and a notification unit 8. Each of these components will be described below in order.

[0039] As shown in FIG. 2, the measurement unit 6 includes an operation amount measurement unit 60, a temperature measurement unit 61, a rotation speed measurement unit 62, and a differential pressure measurement unit 63. The operation amount measurement unit 60 measures the operation amount of the actuators 30, 31 (hereinafter, this may be simply referred to as the "operation amount") and is configured, for example, by a pressure sensor that measures the pilot pressure output from the remote control valve 15c. The temperature measurement unit 61 measures the temperature (hereinafter, this may be simply referred to as the "oil temperature") of the return oil (particularly the return oil upstream of the return filter 42) and is configured, for example, by a temperature sensor. The rotation speed measurement unit 62 measures the rotation speed of the engine 16 (hereinafter, this may be simply referred to as the "engine rotation speed") and is configured, for example, by a rotation speed sensor. The differential pressure measurement unit 63 measures the differential pressure before and after the return filter 42 (the difference between the pressure downstream of the return filter 42 and the pressure upstream of the return filter 42; hereinafter, this may be simply referred to as the "filter differential pressure") and is configured, for example, by a differential pressure sensor.

[0040] The control unit 7 is configured, for example, by a controller (for example, an ECU: Electronic Control Unit) mounted on the construction machine 1, and has a processing unit 70 consisting of a processor such as a CPU (Central Processing Unit), and a storage unit 71 consisting of RAM, ROM, etc. The control unit 7 is electrically connected to each part of the measurement unit 6, and is configured to be able to acquire various measurement values. The control unit 7 is also configured to be able to control the pump 17, etc.

[0041] The processing unit 70 has a first determination unit 72, a second determination unit 73, and a clogging determination unit 74, and each of these units performs various processes by executing a program stored in a storage unit 71. The processes performed by each of these units will be described in detail later with reference to flowcharts. In addition to the various programs, the storage unit 71 stores various parameters, various thresholds and a threshold table 75, which will be described later, and the like.

[0042] The notification unit 8 notifies an operator, etc., and is composed of, for example, a display device and an audio device. The timing of notification by the notification unit 8 will be explained later with reference to a flowchart.

[0043] (Processing procedure by the control unit) Fig. 3 is a flowchart showing an example of a processing procedure by the control unit 7 of the abnormality detection device 5. Fig. 4 is a flowchart showing an example of a processing procedure by the first determination unit 72. Next, the processing procedure by the control unit 7 of the abnormality detection device 5 in the first embodiment will be described with reference to the flowcharts of Fig. 3 and Fig. 4. The processing shown in Fig. 3 is executed, for example, after the return filter 42 has been replaced and immediately after the engine 16 has started.

[0044] 3, first, in step S1, the first determination unit 72 of the processing unit 70 determines the state of the return oil. Specifically, the first determination unit 72 determines whether the return oil is in a predetermined state where the pressure is higher than a predetermined pressure. The predetermined pressure is determined, for example, by a previously conducted experiment.

[0045] The pressure of the return oil varies depending on the amount of operation of the actuators 30, 31, the temperature of the return oil, the rotation speed of the engine 16, and the like. For example, as the amount of operation of the actuators 30, 31 changes, the flow rate of the return oil from the actuators 30, 31 changes, which in turn changes the pressure of the return oil. Furthermore, as the temperature of the return oil decreases, the viscosity of the return oil increases, which in turn increases the pressure of the return oil. Furthermore, as the rotation speed of the engine 16, which is the driving source of the pump 17 that supplies hydraulic oil to the actuators 30, 31, increases, the flow rate of the return oil from the actuators 30, 31 increases, which in turn increases the pressure of the return oil. Taking these factors into consideration, for example, the first determination unit 72 determines whether the return oil is in a predetermined state based on the amount of operation measured by the operation amount measurement unit 60, the temperature measured by the temperature measurement unit 61, and the rotation speed measured by the rotation speed measurement unit 62. The specific determination procedure performed by the first determination unit 72 is described below.

[0046] 4, in step S10, the first determination unit 72 acquires the operation amount from the operation amount measuring unit 60, acquires the oil temperature from the temperature measuring unit 61, and acquires the engine speed from the speed measuring unit 62. In step S11, the first determination unit 72 determines whether the operation amount acquired from the operation amount measuring unit 60 satisfies a predetermined condition. For example, the first determination unit 72 determines whether the pilot pressure acquired from the operation amount measuring unit 60 is equal to or greater than a predetermined pilot pressure threshold.

[0047] As a further specific example, the first determination unit 72 refers to the memory unit 71 for the type of operation of the actuators 30 and 31 and determines whether the operation amount acquired from the operation amount measurement unit 60 is equal to or greater than a predetermined operation amount threshold during the retraction operation of the hydraulic cylinder constituting the actuator 31. This determination is made based on the fact that during the retraction operation of the hydraulic cylinder, the flow rate of the return oil tends to be higher than during the extension operation of the hydraulic cylinder due to the difference in cross-sectional area between the rod-side oil chamber 32 (see FIG. 2 ) on the supply side to which hydraulic oil is supplied and the head-side oil chamber 33 on the discharge side to which return oil is discharged. As a result, the pressure of the return oil tends to be higher than during the extension operation of the hydraulic cylinder. If it is determined that the operation amount acquired from the operation amount measurement unit 60 is equal to or greater than the predetermined operation amount threshold, the process proceeds to step S12. If it is determined that the operation amount acquired from the operation amount measurement unit 60 is not equal to or greater than the predetermined operation amount threshold, the process by the abnormality detection device 5 ends.

[0048] In step S12, the first determination unit 72 determines whether the oil temperature acquired from the temperature measurement unit 61 is equal to or lower than a predetermined temperature threshold. If it is determined that the oil temperature acquired from the temperature measurement unit 61 is equal to or lower than the predetermined temperature threshold, the process proceeds to step S13, and if it is determined that the oil temperature acquired from the temperature measurement unit 61 is not equal to or lower than the predetermined temperature threshold, the process by the abnormality detection device 5 ends.

[0049] In step S13, the first determination unit 72 determines whether the engine speed acquired from the speed measurement unit 62 is equal to or greater than a predetermined speed threshold. If it is determined that the engine speed acquired from the speed measurement unit 62 is equal to or greater than the predetermined speed threshold, the process proceeds to step S14, and if it is determined that the engine speed acquired from the speed measurement unit 62 is not equal to or greater than the predetermined speed threshold, the process by the abnormality detection device 5 ends.

[0050] If step S14 is reached after steps S11 to S13 as described above, the determination result by the first determination unit 72 is "the return oil is in the predetermined state." Otherwise, the determination result by the first determination unit 72 is "the return oil is not in the predetermined state." When the return oil is in the predetermined state, that is, when the pressure of the return oil is higher than the predetermined pressure, it is expected that the pressure on the return filter 42 (see FIG. 2) will be higher than when it is not in the predetermined state. For example, when the return oil is in the predetermined state, if the return filter 42 is a genuine, non-defective product and properly assembled (no filter abnormality), even if the return filter 42 is a new product that is free of foreign matter and therefore easily allows return oil to pass through, the pressure on the return filter 42 will be higher than when the return oil is not in the predetermined state, and the differential pressure before and after the return filter 42 (filter differential pressure) will be higher.

[0051] On the other hand, if the return filter 42 is a non-genuine product, e.g., one with a coarser mesh than the genuine product, a defective product, or is not properly assembled (there is a filter abnormality), the pressure on the return filter 42 will not be as high as when the return oil is not in a predetermined state, and the filter differential pressure will not be as high. Therefore, when the return oil is in a predetermined state (a state in which the pressure is higher than the predetermined pressure), the difference between the filter differential pressure when there is no filter abnormality and the filter differential pressure when there is a filter abnormality will be more significant than when there is not. This makes it easier to determine whether there is a filter abnormality based on the filter differential pressure. In other words, the first determination unit 72 determines whether the return oil is in a predetermined state, thereby making it possible to determine whether there is a filter abnormality based on the filter differential pressure.

[0052] Returning to FIG. 3, in step S2, the second determination unit 73 of the processing unit 70 acquires the filter differential pressure from the differential pressure measurement unit 63. In step S3, the second determination unit 73 determines whether or not there is a filter abnormality based on the filter differential pressure. Specifically, the second determination unit 73 determines whether or not the filter differential pressure acquired from the differential pressure measurement unit 63 is less than a predetermined differential pressure threshold (hereinafter, this may be referred to as a "filter differential pressure determination step"). This determination is made on the basis that, as described above, if there is a filter abnormality, the filter differential pressure will not be very high.

[0053] The flow rate of return oil discharged from the actuators 30, 31 may vary depending on the type of operation of the actuators 30, 31. For example, as described above, the flow rate of return oil tends to be higher when the hydraulic cylinder constituting the actuator 31 is retracted compared to when the hydraulic cylinder is extended. Conversely, the flow rate of return oil tends to be lower when the hydraulic cylinder is extended compared to when the hydraulic cylinder is retracted due to the difference in cross-sectional area between the head-side oil chamber 33 on the supply side (see FIG. 2) and the rod-side oil chamber 32 on the discharge side. Furthermore, the flow rate of return oil when the hydraulic motor constituting the actuator 30 is operated tends to be lower than the flow rate of return oil when the hydraulic cylinder is retracted and higher than the flow rate of return oil when the hydraulic cylinder is extended.

[0054] In this way, when the flow rate of return oil differs depending on the type of operation of the actuators 30, 31, the pressure of the return oil differs, and therefore the range of the filter differential pressure when a filter abnormality exists also differs depending on the type of operation of the actuators 30, 31. Based on this, for example, the second determination unit 73 uses a predetermined differential pressure threshold value according to the type of operation of the actuators 30, 31 in the filter differential pressure determination step in step S3. Specifically, this is as follows.

[0055] Fig. 5 is a diagram showing an example of the threshold value table 75. As shown in Fig. 5, the threshold value table 75 associates types of operation of the actuators 30, 31 (item "operation type") with predetermined differential pressure threshold values ​​for each type (item "threshold value"). Operation A in the item "operation type" of the threshold value table 75 is, for example, a contraction operation of the hydraulic cylinder that constitutes the actuator 31, operation B is, for example, an operation of the hydraulic motor that constitutes the actuator 30, and operation C is, for example, an extension operation of the hydraulic cylinder that constitutes the actuator 31. Threshold values ​​TH1 to TH3 in the item "operation type" are predetermined differential pressure threshold values ​​that correspond to operations A to C, respectively, and there is a relationship of threshold value TH1 > threshold value TH2 > threshold value TH3.

[0056] 3, the second determination unit 73 refers to the memory unit 71 for the type of operation of the actuators 30, 31 and also refers to the threshold value table 75, and determines whether the filter differential pressure acquired from the differential pressure measurement unit 63 is less than the predetermined differential pressure threshold value in the threshold value table 75 that corresponds to the type of operation of the actuators 30, 31. If it is determined that the filter differential pressure acquired from the differential pressure measurement unit 63 is less than the predetermined differential pressure threshold value, the process proceeds to step S4, and on the other hand, if it is determined that the filter differential pressure acquired from the differential pressure measurement unit 63 is not less than the predetermined differential pressure threshold value, the process proceeds to step S5.

[0057] When the process reaches step S4 after passing through the filter differential pressure determination step in step S3 described above, the determination result by the second determination unit 73 is "filter abnormality exists." At this time, for example, the notification unit 8 issues a notification urging the operator or the like to check the return filter 42. On the other hand, when the process reaches step S5, the determination result by the second determination unit 73 is "no filter abnormality exists." In this way, the second determination unit 73 determines that a filter abnormality exists when the differential pressure (filter differential pressure) measured by the differential pressure measurement unit 63 is less than the predetermined differential pressure threshold corresponding to the type of operation of the actuators 30, 31 in the threshold table 75. As a result, the predetermined differential pressure threshold corresponding to the type of operation of the actuators 30, 31 is used in the filter differential pressure determination step in step S3, so that it is possible to more accurately determine whether or not a filter abnormality exists depending on the type of operation of the actuators 30, 31.

[0058] As explained above, the second judgment unit 73 judges that there is a filter abnormality when the first judgment unit 72 judges that the return oil is in a predetermined state (when step S14 is reached after steps S11 to S13) and when the differential pressure (filter differential pressure) measured by the differential pressure measurement unit 63 is less than a predetermined differential pressure threshold (when step S4 is reached after the filter differential pressure judgment step in step S3).

[0059] That is, the filter differential pressure determination step in step S3 is executed when the first determination unit 72 determines that the return oil is in a predetermined state, that is, when it is easy to determine whether or not there is a filter abnormality based on the filter differential pressure. This makes it possible to accurately determine whether or not there is a filter abnormality based on the filter differential pressure measured by the differential pressure measurement unit 63. In this way, the abnormality detection device 5 described above can accurately detect an abnormality related to the return filter 42.

[0060] Furthermore, as a secondary effect, as described above, the filter differential pressure determination step in step S3 is executed when it is easy to determine whether or not there is a filter abnormality based on the filter differential pressure. Therefore, it becomes possible to accurately determine whether or not there is a filter abnormality without using a high-precision, expensive differential pressure sensor or the like, thereby reducing the manufacturing cost of the abnormality detection device 5.

[0061] Furthermore, as described above, the first judgment unit 72 judges whether or not the return oil is in a predetermined state based on the operation amount measured by the operation amount measuring unit 60, the temperature (oil temperature) measured by the temperature measuring unit 61, and the rotation speed measured by the rotation speed measuring unit 62. As a result, multiple judgments (steps S11 to S13) are performed based on the operation amount measured by the operation amount measuring unit 60, the temperature measured by the temperature measuring unit 61, and the rotation speed measured by the rotation speed measuring unit 62, and therefore it is possible to more accurately judge whether or not the return oil is in a predetermined state.

[0062] In addition to the above-described processing, although not shown in a flowchart, the clogging determination unit 74 of the control unit 7 acquires the filter differential pressure from the differential pressure measurement unit 63 as in step S2 above (see FIG. 3 ), and then determines whether the filter differential pressure acquired from the differential pressure measurement unit 63 is equal to or greater than a predetermined clogging threshold. The clogging determination unit 74 determines that clogging has occurred in the return filter 42 when the differential pressure measured by the differential pressure measurement unit 63 is equal to or greater than the predetermined clogging threshold. The clogging determination unit 74 in this manner can detect clogging of the return filter 42.

[0063] The above-mentioned various thresholds (predetermined pilot pressure threshold, predetermined operation amount threshold, predetermined temperature threshold, predetermined rotation speed threshold, predetermined clogging threshold, etc.) and the thresholds in the threshold table 75 are determined, for example, by experiments conducted in advance.

[0064] FIG. 6 is a graph showing an example of the execution timing of the processing by the control unit 7 of the abnormality detection device 5. FIG. 6 shows an example of the relationship between the filter differential pressure (vertical axis) and time (horizontal axis) acquired by the second determination unit 73 from the differential pressure measurement unit 63 in step S2 (see FIG. 3) during the processing by the control unit 7. The series of steps of the processing by the control unit 7 described above may be repeated until the determination result by the second determination unit 73 is "there is a filter abnormality", or may be repeated at regular time intervals. For example, as shown in FIG. 6, the processing by the control unit 7 is performed after the return filter 42 is replaced at timing Tg and immediately after the engine 16 is started at timing Te, and at timing t (1-1) , t (1-2) , t (1-3) , t (1-n) In addition, if the result of the determination by the first determination unit 72 is "the return oil is not in the predetermined state," the above step S2 (see FIG. 3) cannot be reached, and therefore no data point for the filter differential pressure can exist.

[0065] Also, timing t (1-n) After the timing Ti, the time to replace the return filter 42 comes. If, for example, a non-genuine product or a defective product is installed at the timing Ti, or if the return filter 42 is not installed properly, the next timing t (2-1) In the process performed by the control unit 7 in step 2, it is determined that the filter differential pressure acquired from the differential pressure measurement unit 63 is less than the predetermined differential pressure threshold, and the determination result by the second determination unit 73 is "there is a filter abnormality."

[0066] Furthermore, in order to detect a filter abnormality early after the replacement of the return filter 42, for example, when the temperature measured by the temperature measuring unit 61 becomes equal to or lower than a predetermined temperature threshold for the first time after the replacement of the return filter 42 (for example, after each timing Tg, Ti), the notification unit 8 issues a notification to prompt the contraction operation of the hydraulic cylinder constituting the actuator 31 so that the operation amount measured by the operation amount measuring unit 60 becomes equal to or higher than a predetermined operation amount threshold and the rotation speed measured by the rotation speed measuring unit 62 becomes equal to or higher than a predetermined rotation speed threshold. This allows for early detection of a filter abnormality after the replacement of the return filter 42 (for example, after each timing t (1-1) , t (2-1) Therefore, the return oil can be kept in a predetermined state, and therefore, whether or not there is a filter abnormality can be determined early by the second determination unit 73. In this way, an abnormality in the return filter 42 can be detected early after the return filter 42 is replaced.

[0067] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and the following modifications may be adopted, for example.

[0068] The undercarriage 10 may be a wheel type. The motor constituting the actuator 30 may be an electric motor. The operation unit 15 may be arranged outside the cab 12 so that the operator can remotely operate the construction machine 1. Accordingly, the operation quantity measuring unit 60 may be arranged outside the cab 12.

[0069] The control unit 7 does not have to have the clogging determination unit 74. The various programs, various parameters, various thresholds, threshold table 75, etc. may be stored in a storage device (for example, a server on the cloud) that can communicate with the control unit 7 via a network. Furthermore, the control unit 7 may be configured to include a processing device (for example, a server on the cloud) that can communicate with a controller mounted on the construction machine 1 via a network. For example, the controller may be configured to transmit various measurement values ​​acquired from each part of the measurement unit 6 to the processing device, and the processing device may execute some or all of the processing by the control unit 7 described above. This makes it possible to reduce the load on the controller mounted on the construction machine 1.

[0070] Furthermore, the abnormality detection device 5 may not be provided with the alarm unit 8, and the alarm unit 8 may be configured to transmit the judgment result (for example, the judgment result by the second judgment unit 73) to an external server, service center, etc. via a network.

[0071] The control valve 41 may be electric. Accordingly, the operation unit 15 may not include the remote control valve 15c and may be configured to output an electric signal to the control valve 41 in response to an operation by the operator. Furthermore, accordingly, the operation amount measuring unit 60 may be configured to measure the electric signal output from the operation unit 15, or the control unit 7 may have this function as the operation amount measuring unit 60. Furthermore, the operation amount measuring unit 60 may be configured as an angle sensor that measures the angle of the travel lever 15a and the control lever 15b of the operation unit 15. Depending on the configuration of the operation amount measuring unit 60, the first determination unit 72 in the control unit 7 may determine whether the operation amount acquired from the operation amount measuring unit 60 in step S11 (see FIG. 4) is equal to or less than a predetermined threshold value or within a predetermined range.

[0072] The differential pressure measuring unit 63 may be composed of one differential pressure sensor as shown in FIG. 2, or may be composed of two pressure sensors (not shown) that measure the pressure downstream and upstream of the return filter 42, respectively.

[0073] In the embodiment described above, the first determination unit 72 determines whether the return oil is in a predetermined state based on the operation amount measured by the operation amount measuring unit 60, the temperature (oil temperature) measured by the temperature measuring unit 61, and the rotation speed measured by the rotation speed measuring unit 62. However, this is not limiting, and the first determination unit 72 may determine whether the return oil is in a predetermined state based only on the operation amount measured by the operation amount measuring unit 60. This makes it possible to easily determine whether the return oil is in a predetermined state based on the operation amount measured by the operation amount measuring unit 60. For example, the first determination unit 72 may determine whether the operation amount acquired from the operation amount measuring unit 60 satisfies a predetermined condition in the above step S11 (see FIG. 4 ), and proceed directly to step S14 if the operation amount acquired from the operation amount measuring unit 60 satisfies the predetermined condition.

[0074] Furthermore, the first determination unit 72 may determine that the return oil is in a predetermined state when the operation amount measured by the operation amount measuring unit 60 is equal to or greater than a predetermined operation amount threshold during a retraction operation of the hydraulic cylinder that constitutes the actuator 31. As a result, when the return oil is in a state where it has a particularly high pressure during a retraction operation of the hydraulic cylinder, that is, when it is easier to determine whether or not there is a filter abnormality based on the filter differential pressure, the second determination unit 73 executes the filter differential pressure determination step (step S3, see FIG. 3), thereby making it possible to more accurately determine whether or not there is a filter abnormality. For example, the first determination unit 72 may determine whether or not the operation amount measured by the operation amount measuring unit 60 is equal to or greater than a predetermined operation amount threshold in the above step S11 (see FIG. 4), and proceed directly to step S14 if the operation amount measured by the operation amount measuring unit 60 is equal to or greater than the predetermined operation amount threshold.

[0075] Furthermore, the first determination unit 72 may determine that the return oil is in a predetermined state when the temperature (oil temperature) measured by the temperature measurement unit 61 is equal to or lower than a predetermined temperature threshold. This makes it possible to easily determine whether the return oil is in a predetermined state based on the temperature measured by the temperature measurement unit 61. For example, the first determination unit 72 may determine whether the temperature measured by the temperature measurement unit 61 is equal to or lower than the predetermined temperature threshold in step S12 (see FIG. 4) above, and proceed directly to step S14 if the temperature measured by the temperature measurement unit 61 is equal to or lower than the predetermined temperature threshold.

[0076] Furthermore, the first determination unit 72 may determine that the return oil is in the predetermined state when the rotation speed measured by the rotation speed measurement unit 62 is equal to or greater than a predetermined rotation speed threshold. This makes it possible to easily determine whether the return oil is in the predetermined state based on the rotation speed measured by the rotation speed measurement unit 62. For example, the first determination unit 72 may determine whether the rotation speed measured by the rotation speed measurement unit 62 is equal to or greater than a predetermined rotation speed threshold in step S13 (see FIG. 4) above, and proceed directly to step S14 when the rotation speed measured by the rotation speed measurement unit 62 is equal to or greater than the predetermined rotation speed threshold.

[0077] Furthermore, in light of the fact that the pressure of the return oil changes depending on the temperature of the return oil and that the temperature of the hydraulic oil stored in tank 40 also changes depending on the temperature of the return oil, a hydraulic oil temperature sensor may be provided that measures the temperature of the hydraulic oil stored in tank 40, and first determination unit 72 may determine whether or not the return oil is in a predetermined state based on the temperature of the hydraulic oil measured by the hydraulic oil temperature sensor as an alternative or supplement to the determination based on the temperature (oil temperature) measured by temperature measurement unit 61 (step S12, see FIG. 4). This makes it possible to easily determine whether or not the return oil is in a predetermined state based on the temperature of the hydraulic oil measured by the hydraulic oil temperature sensor.

[0078] Furthermore, a flow rate sensor that measures the flow rate of return oil may be provided upstream of the return filter 42 (see FIG. 2), and the first determination unit 72 may determine whether the return oil is in a predetermined state based on the flow rate measured by the flow rate sensor. This makes it possible to easily determine whether the return oil is in a predetermined state based on the flow rate measured by the flow rate sensor.

[0079] Furthermore, the first determination unit 72 may determine whether or not the return oil is in a predetermined state based on one or more of the operation amount measured by the operation amount measuring unit 60, the temperature measured by the temperature measuring unit 61, the rotation speed measured by the rotation speed measuring unit 62, the temperature of the hydraulic oil measured by the hydraulic oil temperature sensor, and the flow rate measured by the flow rate sensor. This allows the measurement unit 6 and the first determination unit 72 to be freely designed to suit the construction machine 1, thereby improving the degree of freedom in designing the abnormality detection device 5.

[0080] The above-described embodiments are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention should not be interpreted solely by the above-described embodiments and examples, but should be defined by the claims. Furthermore, all modifications and variations within the scope of the claims are within the scope of the present invention. [Explanation of symbols]

[0081] 1. Construction machinery 16 Engine 17 Pump 30, 31 (31A, 31B, 31C) Actuator 42 Return filter 5. Anomaly detection device 6 Measuring part 60 Operation amount measuring section 61 Temperature measurement section 62 Rotational speed measurement unit 63 Differential pressure measurement section 7 Control Unit 72 1st Judgment Section 73 Second judgment part 74 Clogging detection unit 75 Threshold Table 8. Notification Department

Claims

1. A filter abnormality detection device that detects a filter abnormality, which is an abnormality related to a return filter through which return oil from an actuator in a construction machine passes, A differential pressure measuring unit that measures a differential pressure before and after the return filter, and a control unit are provided, The control unit a first determination unit that determines whether the return oil is in a predetermined state in which the pressure is higher than a predetermined pressure; A filter abnormality detection device having a second judgment unit that judges that the filter is abnormal when the first judgment unit judges that the return oil is in the specified state and when the differential pressure measured by the differential pressure measurement unit is less than a specified differential pressure threshold.

2. 2. The filter abnormality detection device according to claim 1, an operation amount measuring unit for measuring an operation amount of the actuator, The first determination unit determines whether the return oil is in the predetermined state based on the operation amount measured by the operation amount measurement unit.

3. 2. The filter abnormality detection device according to claim 1, a temperature measuring unit for measuring the temperature of the return oil; The first determination unit determines that the return oil is in the predetermined state when the temperature measured by the temperature measurement unit is equal to or lower than a predetermined temperature threshold.

4. 2. The filter abnormality detection device according to claim 1, a rotation speed measuring unit that measures the rotation speed of an engine that is a drive source of a pump that supplies hydraulic oil to the actuator; The first determination unit determines that the return oil is in the predetermined state when the rotation speed measured by the rotation speed measurement unit is equal to or greater than a predetermined rotation speed threshold.

5. 2. The filter abnormality detection device according to claim 1, an operation amount measuring unit that measures an operation amount of the actuator; a temperature measuring unit for measuring the temperature of the return oil; a rotation speed measurement unit that measures the rotation speed of an engine that is a drive source of a pump that supplies hydraulic oil to the actuator, The first determination unit A filter abnormality detection device that determines whether the return oil is in the specified state based on the operation amount measured by the operation amount measuring unit, the temperature measured by the temperature measuring unit, and the rotation speed measured by the rotation speed measuring unit.

6. 3. The filter abnormality detection device according to claim 2, The actuator is composed of a hydraulic cylinder, The first determination unit determines that the return oil is in the predetermined state when the operation amount measured by the operation amount measurement unit is equal to or greater than a predetermined operation amount threshold during the contraction operation of the hydraulic cylinder.

7. 2. The filter abnormality detection device according to claim 1, The second determination unit referencing a threshold value table that associates the type of operation of the actuator with the predetermined differential pressure threshold value for each type; The filter abnormality detection device determines that the filter is abnormal when the differential pressure measured by the differential pressure measurement unit is less than the predetermined differential pressure threshold value corresponding to the type of operation of the actuator in the threshold value table.

8. 2. The filter abnormality detection device according to claim 1, The control unit The filter abnormality detection device further comprises a clogging determination unit that determines that clogging has occurred in the return filter when the differential pressure measured by the differential pressure measurement unit is equal to or greater than the predetermined clogging threshold value.

9. 6. The filter abnormality detection device according to claim 5, The actuator is composed of a hydraulic cylinder, a filter abnormality detection device including an alarm unit that issues an alarm to prompt the hydraulic cylinder to contract when the temperature measured by the temperature measurement unit falls below a predetermined temperature threshold for the first time after the return filter has been replaced, so that the operation amount measured by the operation amount measurement unit becomes equal to or greater than a predetermined operation amount threshold and the rotation speed measured by the rotation speed measurement unit becomes equal to or greater than a predetermined rotation speed threshold.

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