Abnormality detection system for hydraulic rotary machine

Abstract

An abnormality detection system (7) for a hydraulic rotary machine (1) according to an embodiment includes: a pressure gauge (71) that measures pressure relating to the hydraulic rotary machine (1); and a processing circuit (73). The processing circuit (73) performs frequency analysis of a pressure waveform, which is the measurement result of the pressure gauge (71), a plurality of times to create a frequency spectrum, records the pressure amplitude of a specific order component that is an integral multiple of the rotation frequency in the frequency spectrum, calculates the occurrence frequency of each value of the recorded pressure amplitude, and determines the presence or absence of an abnormality in the hydraulic rotary machine (1) on the basis of a temporal change in a frequency curve on a graph relating to the pressure amplitude and the occurrence frequency.

Description

Hydraulic rotating machinery fault detection system

[0001] The present disclosure relates to an abnormality detection system for a hydraulic rotating machine.

[0002] Various methods are used to detect abnormalities in hydraulic rotating machines such as hydraulic pumps and hydraulic motors. For example, Patent Document 1 discloses an abnormality detection device that detects abnormalities in a hydraulic pump using the discharge pressure or drain pressure of the hydraulic pump.

[0003] Specifically, the abnormality detection device in Patent Document 1 measures the discharge pressure or drain pressure of a hydraulic pump with a pressure gauge, performs frequency analysis on the pressure waveform measured by the pressure gauge to create a frequency spectrum, and determines the presence or absence of an abnormality by comparing the pressure amplitude of a rotational frequency in the frequency spectrum with a threshold value. Note that the rotational frequency is N / 60 [Hz] when the rotational speed of the hydraulic pump is N [rpm].

[0004] JP 2013-170509 A

[0005] However, when the pressure amplitude of the rotational frequency in the frequency spectrum is compared with a threshold value, as in the anomaly detection device of Patent Document 1, it is vulnerable to disturbances and may erroneously determine whether or not an anomaly exists. Note that disturbances include the influence of individual differences in hydraulic rotating machines, the influence of noise specific to construction or industrial machines in which the hydraulic rotating machine is installed, and the influence of the operating location of the construction or industrial machines in which the hydraulic rotating machine is installed.

[0006] Therefore, an object of the present disclosure is to provide an abnormality detection system for a hydraulic rotating machine that can accurately determine whether or not an abnormality exists in the hydraulic rotating machine.

[0007] From a first aspect, the present disclosure provides an abnormality detection system for a hydraulic rotating machine, comprising: a pressure gauge that measures pressure related to a hydraulic rotating machine; and a processing circuit that performs frequency analysis on a pressure waveform that is a measurement result of the pressure gauge over a plurality of times to create a frequency spectrum, records pressure amplitudes of specific order components that are integer multiples of the rotational frequency in the frequency spectrum, calculates an occurrence frequency for each value of the recorded pressure amplitude, and determines whether or not there is an abnormality in the hydraulic rotating machine based on changes over time in a frequency curve on a graph relating to the pressure amplitude and the occurrence frequency.

[0008] From a second aspect, the present disclosure provides an abnormality detection system for a hydraulic rotating machine, comprising: a pressure gauge that measures pressure related to a hydraulic rotating machine; and a processing circuit that performs frequency analysis on a pressure waveform that is a measurement result of the pressure gauge over a plurality of times to create a frequency spectrum, records pressure amplitudes of specific order components that are integer multiples of the rotational frequency in the frequency spectrum, uses at least one of the average value and dispersion of the recorded pressure amplitudes as an index value, and determines whether or not there is an abnormality in the hydraulic rotating machine based on changes in the index value over time.

[0009] According to the present disclosure, an abnormality detection system for a hydraulic rotating machine is provided that can accurately determine whether or not there is an abnormality in the hydraulic rotating machine.

[0010] 4A to 4C are graphs relating to pressure amplitude and occurrence frequency, with FIG. 4A showing a hydraulic circuit including an axial piston pump that is a hydraulic rotary machine, and an abnormality detection system according to a first embodiment. FIG. 4B shows a graph illustrating a pressure waveform generated by frequency analysis of the hydraulic rotary machine. FIG. 4C shows a graph illustrating a pressure amplitude and occurrence frequency, with FIG. 4A showing a state when the hydraulic rotary machine is normal, FIG. 4B showing a state when an abnormality has occurred in the hydraulic rotary machine, and FIG. 4C showing a state when the abnormal condition of the hydraulic rotary machine has worsened.

[0011] First Embodiment

[0012] 1 shows an abnormality detection system 7 for a hydraulic rotating machine 1 according to a first embodiment. In this embodiment, the hydraulic rotating machine 1 is an axial piston pump 1A mounted on construction machinery such as a hydraulic excavator or industrial machinery such as a press. However, the hydraulic rotating machine 1 may also be an axial piston motor.

[0013] The axial piston pump 1A, together with a tank 81 and at least one hydraulic actuator 83, constitutes a hydraulic circuit 8 of a construction machine or industrial machine. Although the number of hydraulic actuators 83 is two in Fig. 1, the number of hydraulic actuators 83 may be one, or three or more. The hydraulic fluid used in the hydraulic circuit 8 is typically oil.

[0014] In the hydraulic circuit 8, a control valve 82 is interposed between the axial piston pump 1A and each hydraulic actuator 83. Each control valve 82 is connected to the corresponding hydraulic actuator 83 by a pair of supply and discharge lines 95. Each hydraulic actuator 83 may be a hydraulic cylinder or a hydraulic motor.

[0015] The axial piston pump 1A is connected to a tank 81 by a suction line 91, and is connected to all of the control valves 82 by a discharge line 93. All of the control valves 82 are connected to the tank 81 by tank lines 94. Furthermore, the axial piston pump 1A is connected to the tank 81 by a drain line 92.

[0016] The axial piston pump 1A is driven by a prime mover 10, which is an engine or an electric motor. In this embodiment, the axial piston pump 1A is a variable displacement swash plate pump. However, the axial piston pump 1A may also be a bent-axis pump. Furthermore, when the prime mover 10 is an electric motor or depending on the hydraulic circuit 8, the axial piston pump 1A may also be a fixed displacement pump.

[0017] The displacement angle, i.e., the displacement, of the axial piston pump 1A is changed by a regulator 15. In this embodiment, a displacement command pressure is introduced to the regulator 15 through a command pressure line 16. For example, the regulator 15 may include a servo piston connected to a swash plate 61 (described later) of the axial piston pump 1A, and change the hydraulic pressure acting on the servo piston in accordance with the displacement command pressure. Alternatively, the regulator 15 may be an electric actuator connected to the swash plate 61.

[0018] As shown in Figure 2, the axial piston pump 1A includes a hollow casing 2 and a rotary shaft 11 extending from the inside to the outside of the casing 2. The rotary shaft 11 is rotated by the above-mentioned prime mover 10. Arranged within the casing 2 are a valve plate 3, a cylinder block 4, a swash plate 61, and a support base 62.

[0019] For ease of explanation, the axial direction of the rotating shaft 11 will be referred to as the front-to-rear direction (one end located outside the casing 2 will be referred to as the front, and the other end will be referred to as the rear), and the two directions perpendicular to the axial direction of the rotating shaft 11 will be referred to as the up-down direction (the upper side of Figure 2 will be referred to as the upside, and the lower side will be referred to as the downside) and the left-to-right direction.

[0020] The casing 2 includes a container-shaped casing body 21 that opens rearward, and a valve cover 22 that closes the opening of the casing body 21. The rotating shaft 11 passes through the bottom of the casing body 21. The bottom of the casing body 21 and the valve cover 22 respectively hold bearings 12 and 13 that rotatably support the rotating shaft 11.

[0021] The valve plate 3 is attached to the front surface of the valve cover 22. The valve plate 3 is provided with a first port 31 and a second port 32, which are arc-shaped and face in opposite directions. In Fig. 2, the first port 31 is depicted at the top dead center on the upper side and the second port 32 at the bottom dead center on the lower side, but the first port 31 and the second port 32 are actually located on both sides of the rotary shaft 11 in the left-right direction perpendicular to the direction of separation between the top dead center and the bottom dead center. The top dead center is the position where a piston 51, which will be described later, is at its farthest retraction, and the bottom dead center is the position where the piston 51 is at its farthest advancement.

[0022] In this embodiment, the rotating shaft 11 rotates in one direction. Therefore, the first port 31 is an intake port, and the second port 32 is an exhaust port. That is, in the rotation direction of the rotating shaft 11, the first port 31, which is an intake port, is located downstream of the top dead center and upstream of the bottom dead center, and the second port 32, which is an exhaust port, is located downstream of the bottom dead center and upstream of the top dead center.

[0023] However, the rotating shaft 11 may be rotated in both directions depending on the hydraulic circuit 8. In this case, when the rotating shaft 11 rotates in one direction, the first port 31 becomes the suction port and the second port 32 becomes the discharge port, and when the rotating shaft 11 rotates in the reverse direction, the second port 32 becomes the suction port and the first port 31 becomes the discharge port. Alternatively, when the hydraulic rotating machine 1 is an axial piston motor, when the rotating shaft 11 rotates in one direction, the first port 31 becomes the inlet port and the second port 32 becomes the outlet port, and when the rotating shaft 11 rotates in the reverse direction, the second port 32 becomes the inlet port and the first port 31 becomes the outlet port.

[0024] The valve cover 22 is provided with a first flow path 2a communicating with the first port 31 and a second flow path 2b communicating with the second port 32. The first flow path 2a and the second flow path 2b open to the outer peripheral surface or rear surface of the valve cover 22, and these openings form external connection ports. As described above, in this embodiment, the rotary shaft 11 rotates in one direction, so the first flow path 2a is the intake path and the second flow path 2b is the discharge path.

[0025] The cylinder block 4 is fixed to the rotary shaft 11 and rotates together with the rotary shaft 11 to slide against the valve plate 3. The cylinder block 4 has a plurality of cylinder bores 41 that open forward around the rotary shaft 11. A plurality of pistons 51 are inserted into each of the cylinder bores 41.

[0026] The cylinder block 4 is also provided with cylinder ports 42 extending from each cylinder bore 41 to the valve plate 3. Some of these cylinder ports 42 communicate with the first port 31, and some others communicate with the second port 32.

[0027] A plurality of shoes 52 are attached to the heads of the pistons 51. In this embodiment, the shoes 52 slide on the swash plate 61 via annular shoe plates 53 attached to the swash plate 61. However, the shoe plates 53 may be omitted, and the shoes 52 may slide directly on the swash plate 61. The shoes 52 are held down by a holding plate 54 so as to maintain contact with the shoe plates 53.

[0028] The swash plate 61 is supported by a support base 62 provided at the bottom of the casing body 21 so as to be swingable about a swing axis extending in the left-right direction. As described above, when the regulator 15 includes a servo piston, the angle of the swash plate 61 is changed by the servo piston.

[0029] The inside of the casing 2 is filled with hydraulic fluid that leaks from between the valve plate 3 and the cylinder block 4, or between the piston 51 and the inner circumferential surface of the cylinder bore 41. A drain port 23 is provided in the casing body 21, and the drain port 23 is connected to the tank 81 by a drain pipe 14. In other words, the inside of the casing 2 and the drain pipe 14 constitute the drain line 92 described above.

[0030] 1 , the abnormality detection system 7 includes a first pressure gauge 71 that measures the pressure related to the hydraulic rotating machine 1, which is the axial piston pump 1A, and a processing circuit 73 that is electrically connected to the first pressure gauge 71. In this embodiment, the first pressure gauge 71 is provided in the drain line 92 and measures the drain pressure of the axial piston pump 1A. The first pressure gauge 71 may be provided in the casing main body 21 as shown in FIG. 2 , or in the drain pipe 14.

[0031] In this embodiment, the processing circuit 73 is also electrically connected to the second pressure gauge 72. The second pressure gauge 72 is provided in the command pressure line 16 and measures the tilt command pressure introduced into the regulator 15.

[0032] Furthermore, the processing circuit 73 is also electrically connected to a display 74. When the hydraulic rotating machine 1 is mounted on a construction machine, the display is provided, for example, in the driver's cab. Note that the processing circuit 73 may not be electrically connected to the display 74, but may be connected to the display 74 via a network. In this case, the display 74 may be installed anywhere.

[0033] With respect to processing circuitry 73, the functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, special-purpose processors, integrated circuits, application-specific integrated circuits (ASICs), 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 circuitry. In this disclosure, a circuit, unit, or means is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where hardware is a processor, which is considered a type of circuit, the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or processor.

[0034] The processing circuit 73 determines whether or not there is an abnormality in the hydraulic rotary machine 1, which is the axial piston pump 1A. The method of this determination will be described in detail below.

[0035] First, the processing circuit 73 performs frequency analysis on the pressure waveform, which is the measurement result of the first pressure gauge 71, over multiple times to create the frequency spectrum shown in Fig. 3. When the rotation speed of the hydraulic rotating machine 1 is N [rpm], the rotation frequency f0 is N / 60 [Hz].

[0036] In this embodiment, the processing circuit 73 performs frequency analysis on the pressure waveform that is the measurement result of the first pressure gauge 71 when the capacity of the hydraulic rotating machine 1 is maintained at a predetermined value α that is greater than the minimum value, to create a frequency spectrum. Therefore, even when the construction machine or industrial machine is in operation, it is possible to measure the pressure related to the hydraulic rotating machine 1 under the same conditions. For example, when the minimum value of the capacity of the hydraulic rotating machine 1 is 0% and the maximum value of the capacity of the hydraulic rotating machine 1 is 100%, the predetermined value α may be 50% or more and 100% or less, or may be 70% or more and 100% or less.

[0037] In this embodiment, the processing circuitry 73 performs frequency analysis on the pressure waveform that is the measurement result of the first pressure gauge 71 when the tilt command pressure measured by the second pressure gauge 72 is at its maximum, to create a frequency spectrum. For example, the processing circuitry 73 may create a frequency spectrum every time the tilt command pressure measured by the second pressure gauge reaches its maximum. Alternatively, if the period during which the tilt command pressure measured by the second pressure gauge is maintained at its maximum is long, the processing circuitry 73 may create a frequency spectrum at predetermined intervals. The measurement time of the pressure waveform used to create the frequency spectrum is, for example, 0.5 to 3 seconds.

[0038] It is desirable that the processing circuit 73 create a frequency spectrum by frequency analyzing the pressure waveform that is the measurement result of the first pressure gauge 71 when the capacity of the hydraulic rotating machine 1 is maintained at the predetermined value α and the discharge pressure of the axial piston pump 1A, which is the hydraulic rotating machine 1, is maintained at the predetermined value β. For example, the predetermined value β may be 1 MPa or more and 20 MPa or less, or 1 MPa or more and 10 MPa or less.

[0039] The frequency spectrum includes a plurality of rotational order components that are integer multiples of the rotational frequency f0. For example, the rotational order components include a first rotational order component f1 to a ninth rotational order component f9 that are 1 to 9 times the rotational frequency f0.

[0040] In the case where the hydraulic rotating machine 1 is an axial piston pump 1A as in this embodiment, and the number of pistons 51 is M, the pressure amplitude of the rotational M-th order component, which is M times the rotational frequency f0, becomes large regardless of whether or not there is an abnormality in the hydraulic rotating machine 1. On the other hand, when the hydraulic rotating machine 1 is normal, the pressure amplitude of rotational order components less than the rotational M-th order component becomes small. Figure 3 shows the frequency spectrum when the hydraulic rotating machine 1 is abnormal.

[0041] The processing circuit 73 records the pressure amplitude of a specific order component among the multiple rotational order components in the frequency spectrum. When the hydraulic rotating machine 1 is an axial piston pump 1A, it is desirable that the specific order component be less than the above-mentioned rotational M-th order component. In this embodiment, the processing circuit 73 records the pressure amplitude P1 of the rotational first order component f1.

[0042] Thereafter, the processing circuit 73 calculates the occurrence frequency for each value of the recorded pressure amplitude P1, and creates a graph relating pressure amplitude and occurrence frequency, with the horizontal axis being pressure amplitude and the vertical axis being occurrence frequency, as shown in Figures 4A to 4C, and displays this on the display 74. Figure 4A shows a case where the hydraulic rotating machine is normal, Figure 4B shows a case where an abnormality has occurred in the hydraulic rotating machine, and Figure 4C shows a case where the abnormal condition of the hydraulic rotating machine has worsened.

[0043] The frequency curve on the graph relating to pressure amplitude and occurrence frequency changes depending on the presence or absence and severity of an abnormality in the hydraulic rotating machine 1. As shown in Figure 4A, when the hydraulic rotating machine 1 is normal, the frequency curve forms a narrow, high mountain shape, and when the hydraulic rotating machine 1 is abnormal, as shown in Figures 4B and 4C, the frequency curve forms a wide, low mountain shape.

[0044] Therefore, the processing circuit 73 determines whether or not there is an abnormality in the hydraulic rotating machine 1 based on changes over time in the frequency curve on the graph relating pressure amplitude and occurrence frequency. In this embodiment, the processing circuit 73 determines whether or not there is an abnormality in the hydraulic rotating machine 1 by comparing the current frequency curve with the frequency curve at the beginning of installation. Here, "at the beginning of installation" refers to within one month after the construction machine or industrial machine on which the hydraulic rotating machine 1 is mounted starts operating. However, the processing circuit 73 may also determine whether or not there is an abnormality in the hydraulic rotating machine 1 by comparing frequency curves before and after a predetermined period.

[0045] For example, the processing circuitry 73 may determine that an abnormality has occurred in the hydraulic rotating machine 1 when the height of the current frequency curve becomes lower than the height of the frequency curve at the initial stage of installation by a predetermined value or more. Alternatively, the processing circuitry 73 may determine that an abnormality has occurred in the hydraulic rotating machine 1 when the width of the current frequency curve becomes wider than the width of the frequency curve at the initial stage of installation by a predetermined value or more. Alternatively, the processing circuitry 73 may determine whether or not an abnormality has occurred in the hydraulic rotating machine 1 based on the similarity of the current frequency curve with respect to the initial frequency curve.

[0046] As described above, in the abnormality detection system 7 of this embodiment, the processing circuitry 73 statistically determines the presence or absence of an abnormality in the hydraulic rotating machine 1 using the results of multiple measurements. Furthermore, the frequency curve used to determine the presence or absence of an abnormality changes depending on the presence or absence and the severity of an abnormality in the hydraulic rotating machine 1. Therefore, by making a determination based on the change in the frequency curve over time, it is possible to accurately determine the presence or absence of an abnormality in the hydraulic rotating machine 1.

[0047] Furthermore, in this embodiment, the processing circuit 73 compares the current frequency curve with the frequency curve at the time of installation. The influence of individual differences in the hydraulic rotating machine 1 and the influence of noise specific to the construction machine or industrial machine on which the hydraulic rotating machine 1 is installed are included in both the frequency curve at the time of installation and the current frequency curve. Therefore, by comparing the current frequency curve with the frequency curve at the time of installation, these influences can be offset.

[0048] Furthermore, the processing circuit 73 displays a graph relating to the pressure amplitude and occurrence frequency on the display 74, so that a person looking at the graph can visually determine whether the hydraulic rotating machine 1 is normal or abnormal.

[0049] Second Embodiment Next, a description will be given of an abnormality detection system for a hydraulic rotating machine 1 according to a second embodiment. The abnormality detection system of this embodiment differs from the abnormality detection system 7 of the first embodiment only in the determination method of the processing circuit 73.

[0050] As in the first embodiment, first, the processing circuitry 73 performs frequency analysis on the pressure waveform, which is the measurement result of the first pressure gauge 71, over multiple times to create the frequency spectrum shown in FIG.

[0051] In this embodiment, as in the first embodiment, the processing circuit 73 creates a frequency spectrum by frequency analyzing the pressure waveform that is the measurement result of the first pressure gauge 71 when the capacity of the hydraulic rotating machine 1 is maintained at a predetermined value α that is greater than the minimum value. Therefore, even when the construction machine or industrial machine is in operation, it is possible to measure the pressure related to the hydraulic rotating machine 1 under the same conditions. For example, when the minimum value of the capacity of the hydraulic rotating machine 1 is 0% and the maximum value of the capacity of the hydraulic rotating machine 1 is 100%, the predetermined value α may be 50% or more and 100% or less, or may be 70% or more and 100% or less.

[0052] In this embodiment, the processing circuitry 73 performs frequency analysis on the pressure waveform that is the measurement result of the first pressure gauge 71 when the tilt command pressure measured by the second pressure gauge 72 is at its maximum, to create a frequency spectrum. For example, the processing circuitry 73 may create a frequency spectrum every time the tilt command pressure measured by the second pressure gauge reaches its maximum. Alternatively, if the period during which the tilt command pressure measured by the second pressure gauge is maintained at its maximum is long, the processing circuitry 73 may create a frequency spectrum at predetermined intervals. The measurement time of the pressure waveform used to create the frequency spectrum is, for example, 0.5 to 3 seconds.

[0053] It is desirable that the processing circuit 73 create a frequency spectrum by frequency analyzing the pressure waveform that is the measurement result of the first pressure gauge 71 when the capacity of the hydraulic rotating machine 1 is maintained at the predetermined value α and the discharge pressure of the axial piston pump 1A, which is the hydraulic rotating machine 1, is maintained at the predetermined value β. For example, the predetermined value β may be 1 MPa or more and 30 MPa or less, or 1 MPa or more and 10 MPa or less.

[0054] The processing circuit 73 records the pressure amplitude of a specific order component among the multiple rotational order components in the frequency spectrum. When the hydraulic rotating machine 1 is an axial piston pump 1A, it is desirable that the specific order component be less than the above-mentioned rotational M-th order component. In this embodiment, the processing circuit 73 records the pressure amplitude P1 of the rotational first order component f1.

[0055] Thereafter, the processing circuit 73 uses at least one of the recorded average value Pa of the pressure amplitude P1 and the dispersion rate S as an index value, and determines whether or not there is an abnormality in the hydraulic rotating machine 1 based on changes in the index value over time. In this embodiment, the processing circuit 73 determines whether or not there is an abnormality in the hydraulic rotating machine 1 by comparing the current index value with the index value at the beginning of installation. Here, "at the beginning of installation" refers to within one month after the construction machine or industrial machine on which the hydraulic rotating machine 1 is mounted starts operating. However, the processing circuit 73 may also determine whether or not there is an abnormality in the hydraulic rotating machine 1 by comparing index values ​​before and after a predetermined period.

[0056] Both the mean value Pa and the dispersion S of the pressure amplitude P1 change depending on whether or not there is an abnormality in the hydraulic rotating machine 1 and the degree of the abnormality. The mean value Pa is low when the hydraulic rotating machine 1 is normal, as shown in Figure 4A, and is high when the hydraulic rotating machine 1 is abnormal, as shown in Figures 4B and 4C. On the other hand, the dispersion S is low when the hydraulic rotating machine 1 is normal, as shown in Figure 4A, and is high when the hydraulic rotating machine 1 is abnormal, as shown in Figures 4B and 4C. The dispersion S may be either a variance or a standard deviation.

[0057] For example, the processing circuit 73 may determine that an abnormality has occurred in the hydraulic rotating machine 1 when the average value Pa of the current pressure amplitude P1 becomes higher by a predetermined value or more than the average value Pa of the pressure amplitude P1 at the initial stage of installation. Alternatively, the processing circuit 73 may determine that an abnormality has occurred in the hydraulic rotating machine 1 when the dispersion degree S of the current pressure amplitude P1 becomes higher by a predetermined value or more than the dispersion degree S of the pressure amplitude P1 at the initial stage of installation. Furthermore, the processing circuit 73 may make a determination by combining both conditions.

[0058] Alternatively, the processing circuitry 73 may determine whether or not there is an abnormality in the hydraulic rotating machine 1 based on the amount or rate of change in the index value before and after a predetermined period. For example, if the index value before the predetermined period is A and the index value after the predetermined period is B, the amount of change is B-A and the rate of change is (B-A) / A.

[0059] As described above, in the abnormality detection system 7 of this embodiment, the processing circuitry 73 statistically determines the presence or absence of an abnormality in the hydraulic rotating machine 1 using the results of multiple measurements. Furthermore, the index value, which is at least one of the average value Pa and dispersion degree S of the pressure amplitude P1 used to determine the presence or absence of an abnormality, changes depending on the presence or absence and the degree of the abnormality in the hydraulic rotating machine 1. Therefore, by making a determination based on the change in the index value over time, it is possible to accurately determine the presence or absence of an abnormality in the hydraulic rotating machine 1.

[0060] In this embodiment, the processing circuit 73 compares the current index value with the index value at the time of installation. The influence of individual differences in the hydraulic rotating machine 1 and the influence of noise specific to the construction machine or industrial machine on which the hydraulic rotating machine 1 is installed are included in both the index value at the time of installation and the current index value. Therefore, by comparing the current index value with the index value at the time of installation, these influences can be offset.

[0061] As in the first embodiment, the processing circuit 73 may calculate the occurrence frequency for each value of the recorded pressure amplitude P1, and create a graph relating the pressure amplitude and occurrence frequency to display on the display 74. In this case, a person looking at the graph can visually determine whether the hydraulic rotating machine 1 is normal or abnormal.

[0062] Other Embodiments The present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present disclosure.

[0063] For example, in both the first and second embodiments, when the processing circuit 73 creates a frequency spectrum, it may use the measurement result of the first pressure gauge 71 when the hydraulic actuator 83 is not operating, instead of the measurement result of the first pressure gauge 71 when the tilt command pressure detected by the second pressure gauge 72 is at its maximum. In this case, the second pressure gauge 72 is not necessary.

[0064] The first pressure gauge 71 may measure the discharge pressure of the axial piston pump 1A as the pressure related to the hydraulic rotating machine 1. Even in this case, if the processing circuit 73 performs the same processing as in the above embodiment, it can accurately determine whether or not there is an abnormality in the hydraulic rotating machine 1.

[0065] Furthermore, the hydraulic rotating machine 1 may be a hydraulic pump other than the axial piston pump 1A, such as a vane pump or a gear pump. In this case, the first pressure gauge 71 may measure either the drain pressure or the discharge pressure.

[0066] Furthermore, the hydraulic rotating machine 1 may be a hydraulic motor other than an axial piston motor. When the hydraulic rotating machine 1 is an axial piston motor or a hydraulic motor other than an axial piston motor, the first pressure gauge 71 may measure the drain pressure or the inflow pressure.

[0067] <Summary> In a first aspect, the present disclosure provides an abnormality detection system for a hydraulic rotating machine, comprising: a pressure gauge that measures pressure related to a hydraulic rotating machine; and a processing circuit that performs frequency analysis on a pressure waveform that is a measurement result of the pressure gauge over a plurality of times to create a frequency spectrum, records pressure amplitudes of specific order components that are integer multiples of the rotational frequency in the frequency spectrum, calculates an occurrence frequency for each value of the recorded pressure amplitude, and determines whether or not there is an abnormality in the hydraulic rotating machine based on a change over time in a frequency curve on a graph relating to the pressure amplitude and the occurrence frequency.

[0068] According to the above configuration, the processing circuit statistically determines whether or not there is an abnormality in the hydraulic rotating machine using the results of multiple measurements. Furthermore, the frequency curve used to determine whether or not there is an abnormality changes depending on whether or not there is an abnormality in the hydraulic rotating machine and the severity of the abnormality. Therefore, by making a determination based on the change in the frequency curve over time, it is possible to accurately determine whether or not there is an abnormality in the hydraulic rotating machine.

[0069] In a second aspect, in the first aspect, the hydraulic rotating machine may be installed in a construction machine or an industrial machine, and the processing circuit may determine whether or not there is an abnormality in the hydraulic rotating machine by comparing the current frequency curve with a frequency curve at the time of installation. The influence of individual differences in the hydraulic rotating machine and the influence of noise specific to the construction machine or industrial machine on which the hydraulic rotating machine is installed are included in both the frequency curve at the time of installation and the current frequency curve. Therefore, by comparing the current frequency curve with the frequency curve at the time of installation, these influences can be offset.

[0070] As a third aspect, in the first or second aspect, the processing circuit may display a graph relating to the pressure amplitude and the occurrence frequency on a display. The frequency curve forms a narrow, tall mountain shape when the hydraulic rotating machine is normal, and a wide, short mountain shape when the hydraulic rotating machine is abnormal. Therefore, by displaying a graph including the frequency curve on a display, a person looking at the graph can visually determine whether the hydraulic rotating machine is normal or abnormal.

[0071] In a fourth aspect, from the second aspect, the present disclosure provides an abnormality detection system for hydraulic rotating machinery, comprising: a pressure gauge that measures pressure related to a hydraulic rotating machinery; and a processing circuit that performs frequency analysis on a pressure waveform that is a measurement result of the pressure gauge over a plurality of times to create a frequency spectrum, records pressure amplitudes of specific order components that are integer multiples of the rotational frequency in the frequency spectrum, uses at least one of the average value and the degree of dispersion of the recorded pressure amplitudes as an index value, and determines whether or not there is an abnormality in the hydraulic rotating machinery based on changes in the index value over time.

[0072] According to the above configuration, the processing circuit statistically determines whether or not there is an abnormality in the hydraulic rotating machine using the results of multiple measurements. Furthermore, the index value, which is at least one of the average value and dispersion of the pressure amplitude and is used to determine whether or not there is an abnormality, changes depending on whether or not there is an abnormality in the hydraulic rotating machine and the degree of the abnormality. Therefore, by making a determination based on the change in the index value over time, it is possible to accurately determine whether or not there is an abnormality in the hydraulic rotating machine.

[0073] In a fifth aspect, in the fourth aspect, the hydraulic rotating machine may be installed in a construction machine or an industrial machine, and the processing circuit may determine whether or not there is an abnormality in the hydraulic rotating machine by comparing the current index value with an index value at the time of installation. The influence of individual differences in the hydraulic rotating machine and the influence of noise specific to the construction machine or industrial machine on which the hydraulic rotating machine is installed are included in both the index value at the time of installation and the current index value. Therefore, by comparing the current index value with the index value at the time of installation, these influences can be offset.

[0074] As a sixth aspect, in the fourth or fifth aspect, the processing circuit may calculate an occurrence frequency for each recorded pressure amplitude value, and display a graph relating to the pressure amplitude and the occurrence frequency on a display. The frequency curve will have a narrow, high peak shape when the hydraulic rotating machine is normal, and a wide, low peak shape when the hydraulic rotating machine is abnormal. Therefore, by displaying a graph including the frequency curve on a display, a person looking at the graph can visually determine whether the hydraulic rotating machine is normal or abnormal.

[0075] As a seventh aspect, in any one of the first to sixth aspects, for example, the hydraulic rotary machine may be an axial piston pump or an axial piston motor.

[0076] As an eighth aspect, in any of the first to seventh aspects, the hydraulic rotating machine is a variable displacement axial piston pump mounted on a construction machine or an industrial machine and which, together with at least one hydraulic actuator, constitutes a hydraulic circuit of the construction machine or the industrial machine, the displacement of the hydraulic rotating machine is changed by a regulator, and the processing circuit may create a frequency spectrum by frequency analyzing the pressure waveform obtained by the measurement result of the first pressure gauge when the displacement of the hydraulic rotating machine is maintained at a predetermined value greater than a minimum value. With this configuration, it is possible to measure the pressure related to the hydraulic rotating machine under the same conditions even when the construction machine or the industrial machine is in operation.

[0077] As a ninth aspect, in the eighth aspect, for example, when the minimum value of the capacity of the hydraulic rotating machine is 0% and the maximum value of the capacity of the hydraulic rotating machine is 100%, the predetermined value may be 50% or more and 100% or less.

Claims

1. A hydraulic rotating machine anomaly detection system comprising: a pressure meter that measures pressure related to a hydraulic rotating machine; and a processing circuit that performs frequency analysis on the pressure waveform that is the measurement result of said pressure meter over multiple times to create a frequency spectrum, records the pressure amplitude of a specific order component that is an integer multiple of the rotation frequency in said frequency spectrum, calculates the occurrence frequency for each value of the recorded pressure amplitude, and determines whether or not there is an abnormality in said hydraulic rotating machine based on changes over time in the frequency curve on a graph relating to said pressure amplitude and said occurrence frequency.

2. The hydraulic rotating machine abnormality detection system according to claim 1, wherein the hydraulic rotating machine is mounted on construction machinery or industrial machinery, and the processing circuit determines whether or not there is an abnormality in the hydraulic rotating machine by comparing the current frequency curve with the frequency curve at the time of mounting.

3. The hydraulic rotating machine abnormality detection system according to claim 1 or 2, wherein the processing circuit displays a graph relating to the pressure amplitude and the occurrence frequency on a display.

4. A hydraulic rotating machine anomaly detection system comprising: a pressure meter that measures pressure related to hydraulic rotating machinery; and a processing circuit that performs frequency analysis on the pressure waveform that is the measurement result of said pressure meter over a plurality of times to create a frequency spectrum, records the pressure amplitude of a specific order component that is an integer multiple of the rotation frequency in said frequency spectrum, uses at least one of the average value and dispersion of the recorded pressure amplitude as an index value, and determines whether or not there is an abnormality in said hydraulic rotating machinery based on changes in said index value over time.

5. The hydraulic rotating machine abnormality detection system according to claim 4, wherein the hydraulic rotating machine is mounted on construction machinery or industrial machinery, and the processing circuit determines whether or not there is an abnormality in the hydraulic rotating machine by comparing the current index value with the index value at the time of installation.

6. A hydraulic rotating machine abnormality detection system according to claim 4 or 5, wherein the processing circuit calculates the occurrence frequency for each recorded pressure amplitude value and displays a graph relating to the pressure amplitude and the occurrence frequency on a display.

7. The abnormality detection system for a hydraulic rotating machine according to any one of claims 1, 2, 4 and 5, wherein the hydraulic rotating machine is an axial piston pump or an axial piston motor.

8. An abnormality detection system for hydraulic rotating machinery as set forth in any one of claims 1, 2, 4 and 5, wherein the hydraulic rotating machinery is a variable displacement axial piston pump mounted on construction machinery or industrial machinery and which, together with at least one hydraulic actuator, constitutes a hydraulic circuit of the construction machinery or industrial machinery, the capacity of the hydraulic rotating machinery is changed by a regulator, and the processing circuit performs frequency analysis on the pressure waveform that is the measurement result of the first pressure gauge when the capacity of the hydraulic rotating machinery is maintained at a predetermined value that is greater than a minimum value, to create a frequency spectrum.

9. A hydraulic rotating machine abnormality detection system as described in claim 8, wherein the predetermined value is between 50% and 100% when the minimum value of the capacity of the hydraulic rotating machine is 0% and the maximum value of the capacity of the hydraulic rotating machine is 100%.

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