Abnormality detection system for hydraulic rotary machine

Abstract

According to one aspect of the present invention, there is provided an abnormality detection system for a hydraulic rotary machine, comprising: a pressure gauge that measures a pressure with respect to the hydraulic rotary machine; and a processing circuit that generates a frequency spectrum by performing frequency analysis on a pressure waveform, which is a plurality of measurement results of the pressure gauge, records a pressure amplitude of a specific order component, which is an integral multiple of a rotational frequency, in the frequency spectrum, calculates an occurrence frequency for each value of the recorded pressure amplitude, and generates an occurrence frequency for each value of the occurrence frequency. And determines the presence or absence of an abnormality in the hydraulic rotary machine on the basis of a change over time in a frequency curve on a graph regarding the pressure amplitude and the frequency of occurrence.

Description

Technical Field

[0001] This disclosure relates to an anomaly detection system for hydraulic rotating machinery. Background Technology

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

[0003] Specifically, the anomaly detection device in Patent Document 1 uses a pressure gauge to measure the discharge pressure or drain pressure of a hydraulic pump, performs frequency analysis on the pressure waveform as a result of the pressure gauge measurement to generate a spectrum, and compares the pressure amplitude of the rotational frequency in the spectrum with a threshold to determine whether there is an anomaly. Furthermore, assuming the hydraulic pump's rotational speed is N [rpm], the rotational frequency is N / 60 [Hz]. Existing technical documents Patent documents

[0004] Patent Document 1: Japanese Patent Publication No. 2013-170509 Summary of the Invention The problem that the invention aims to solve

[0005] However, when comparing the pressure amplitude of the rotation frequency in the spectrum with a threshold, as in the anomaly detection device of Patent Document 1, it may incorrectly determine whether there is an anomaly because it is relatively vulnerable to interference. In addition, interferences include the effects of individual differences in hydraulic rotating machinery, the effects of noise specific to engineering or industrial machinery equipped with hydraulic rotating machinery, and the effects of the work site of engineering or industrial machinery equipped with hydraulic rotating machinery.

[0006] Therefore, the purpose of this disclosure is to provide an anomaly detection system for hydraulic rotating machinery that can accurately determine whether there are any abnormalities in the hydraulic rotating machinery. Methods for solving problems

[0007] This disclosure provides, from a first aspect, an anomaly detection system for hydraulic rotating machinery, comprising: a pressure gauge for measuring pressure with respect to the hydraulic rotating machinery; and a processing circuit that performs frequency analysis on multiple pressure gauge measurements, i.e., pressure waveforms, to generate a spectrum, records the pressure amplitude of specific order components in the spectrum that are integer multiples of the rotation frequency, calculates the occurrence frequency for each recorded pressure amplitude value, and determines whether the hydraulic rotating machinery has an anomaly based on the change of the frequency curve over time on a graph of the pressure amplitude and the occurrence frequency.

[0008] This disclosure provides, from a second aspect, an anomaly detection system for hydraulic rotating machinery, comprising: a pressure gauge for measuring pressure with respect to the hydraulic rotating machinery; and a processing circuit that performs frequency analysis on multiple pressure gauge measurements, i.e., pressure waveforms, to generate a spectrum, records the pressure amplitude of a specific order component in the spectrum that is an integer multiple of the rotation frequency, uses at least one of the average value of the recorded pressure amplitude and the dispersion as an index value, and determines whether the hydraulic rotating machinery has an anomaly based on the change of the index value over time. The effects of the invention

[0009] According to this disclosure, an anomaly detection system for hydraulic rotating machinery is provided, which can accurately determine whether there are any abnormalities in hydraulic rotating machinery. Attached Figure Description

[0010] Figure 1 This is a diagram showing a hydraulic circuit including an axial piston pump, which is a hydraulic rotating machine, and an anomaly detection system according to the first embodiment. Figure 2 This is a cross-sectional view of an axial piston pump. Figure 3 It is a spectrum chart created through frequency analysis of the pressure waveform. Figure 4 (include Figure 4 A, Figure 4 B and Figure 4 C) is a graph showing the relationship between pressure amplitude and frequency of occurrence. Figure 4 A represents the normal condition of the hydraulic rotating machinery. Figure 4 B indicates a situation where an abnormality occurs in the hydraulic rotating machinery. Figure 4 C represents the situation when the abnormal condition of the hydraulic rotating machinery deteriorates. Detailed Implementation

[0011] <First Implementation Method>

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

[0013] The axial piston pump 1A, together with the housing 81 and at least one hydraulic actuator 83, constitutes the hydraulic circuit 8 of engineering or industrial machinery. Figure 1 The number of hydraulic actuators 83 is two, but the number of hydraulic actuators 83 can also be one, or even more than three. The hydraulic oil used in the hydraulic circuit 8 is typically oil.

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

[0015] The axial piston pump 1A is connected to the housing 81 via the suction line 91 and to all control valves 82 via the discharge line 93. Furthermore, all control valves 82 are connected to the housing 81 via the housing line 94. Finally, the axial piston pump 1A is connected to the housing 81 via the drain line 92.

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

[0017] The tilt angle, i.e., the capacity, of the axial piston pump 1A is changed by the regulator 15. In this embodiment, the tilt command pressure is introduced into the regulator 15 via the command pressure line 16. For example, the regulator 15 may include a servo piston connected to the swashplate 61 of the axial piston pump 1A (described later), and change the oil pressure acting on the servo piston according to the tilt command pressure. Alternatively, the regulator 15 may also be an electric actuator connected to the swashplate 61.

[0018] like Figure 2 As shown, the axial piston pump 1A includes a hollow housing 2 and a rotating shaft 11 extending from the inside of the housing 2 to the outside. The rotating shaft 11 is rotated by the aforementioned prime mover 10. A distributor plate 3, a cylinder block 4, a swashplate 61, and a support platform 62 are arranged inside the housing 2.

[0019] For ease of explanation, the axial direction of the rotating shaft 11 will be referred to as the front-rear direction (the side located outside the housing 2 is the front, and the other side is the rear), and the two directions orthogonal to the axial direction of the rotating shaft 11 will be referred to as the up-down direction. Figure 2 (The top side is above, and the bottom side is below) and the left and right directions.

[0020] The housing 2 includes a container-shaped housing body 21 that opens to the rear and a valve cover 22 that closes the opening of the housing body 21. A rotating shaft 11 extends through the bottom of the housing body 21. Bearings 12 and 13, which rotatably support the rotating shaft 11, are respectively held at the bottom of the housing body 21 and on the valve cover 22.

[0021] The distribution plate 3 is mounted in front of the valve cover 22. The distribution plate 3 has a first port 31 and a second port 32 with opposite directions of arc shape. Figure 2In the diagram, the first port 31 is depicted at the top dead center (TDC) and the second port 32 is depicted at the bottom dead center (BDC). However, the actual positions of the first port 31 and the second port 32 are located on either side of the rotation axis 11 in a left-right direction orthogonal to the separation direction of the TDC and BDC. Furthermore, the TDC is the final retraction position of the plunger 51, described later, and the BDC is the final forward movement position of the plunger 51.

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

[0023] However, depending on the configuration of hydraulic circuit 8, the rotating shaft 11 can also rotate in both directions. 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; when the rotating shaft 11 rotates in the opposite direction, the second port 32 becomes the suction port and the first port 31 becomes the discharge port. Alternatively, when the hydraulic rotating machinery 1 is an axial piston motor, when the rotating shaft 11 rotates in one direction, the first port 31 becomes the inflow port and the second port 32 becomes the outflow port; when the rotating shaft 11 rotates in the opposite direction, the second port 32 becomes the inflow port and the first port 31 becomes the outflow 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 have openings on the outer peripheral surface or rear of the valve cover 22, and these openings form external connection ports. As described above, in this embodiment, since the rotating shaft 11 rotates in one direction, the first flow path 2a is a suction path and the second flow path 2b is a discharge path.

[0025] The cylinder body 4 is fixed to the rotating shaft 11 and slides with the distributor plate 3 by rotating together with the rotating shaft 11. Multiple cylinder bores 41 with forward openings are provided on the cylinder body 4 around the rotating shaft 11. Multiple plungers 51 are inserted into these cylinder bores 41 respectively.

[0026] In addition, the cylinder block 4 is provided with cylinder block ports 42 that lead from each cylinder bore 41 to the distributor plate 3. Some of these cylinder block ports 42 are connected to the first port 31, and the other few are connected to the second port 32.

[0027] Multiple slippers 52 are mounted on the head of the plunger 51. In this embodiment, the slippers 52 slide with the swashplate 61 via an annular slipper plate 53 mounted on the swashplate 61. However, the slipper plate 53 may be omitted, allowing the slippers 52 to slide directly with the swashplate 61. The slippers 52 are pressed by the pressure plate 54 to maintain contact with the slipper plate 53.

[0028] The swashplate 61 is supported by a support platform 62 located at the bottom of the housing body 21 and is able to swing about a swing axis extending in the left and right direction. As described above, when the regulator 15 includes a servo piston, the angle of the swashplate 61 is changed by the servo piston.

[0029] The interior of housing 2 is filled with hydraulic oil leaking from between the distributor plate 3 and the cylinder 4, or between the plunger 51 and the inner circumferential surface of the cylinder bore 41. A drain port 23 is provided on the housing body 21, and the drain port 23 is connected to the housing 81 via a drain pipe 14. That is, the interior of housing 2 and the drain pipe 14 constitute the aforementioned drain pipeline 92.

[0030] Back Figure 1 The anomaly detection system 7 includes: a first pressure gauge 71, which measures the pressure of the hydraulic rotating machinery 1, which is an axial piston pump 1A; and a processing circuit 73, which is electrically connected to the first pressure gauge 71. In this embodiment, the first pressure gauge 71 is located in the drain line 92 and measures the drain pressure of the axial piston pump 1A. The first pressure gauge 71 is as follows: Figure 2 The oil drain pipe 14 can be installed either on the housing body 21 or on 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 located 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 the display 74. When the hydraulic rotating machinery 1 is mounted on construction machinery, the display is located, for example, in the operator's cab. Alternatively, the processing circuit 73 may not be electrically connected to the display 74, but rather connected to the display 74 via a network. In this case, the display 74 can be installed anywhere.

[0033] Regarding processing circuit 73, the functions of the elements disclosed in this specification can be performed using a general-purpose processor, special-purpose processor, integrated circuit, ASIC (Application Specific Integrated Circuits), conventional circuit, and / or circuit or processing circuit comprising combinations thereof, constructed or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it contains transistors and other circuitry. In this disclosure, a circuit, unit, or means is hardware that performs the listed functions, or hardware programmed to perform the listed functions. The hardware can be the hardware disclosed in this specification, or it can be other known hardware programmed or constructed to perform the listed functions. Where the hardware is a processor considered a circuit, the circuit, means, or unit is a combination of hardware and software used in the construction of the hardware and / or processor.

[0034] The processing circuit 73 determines whether there is any abnormality in the hydraulic rotating machinery 1, which is the axial piston pump 1A. The determination method will be explained in detail below.

[0035] First, the processing circuit 73 performs frequency analysis on the multiple measurement results (i.e., pressure waveforms) from the first pressure gauge 71, and generates... Figure 3 The spectrum shown. Let the rotational speed of the hydraulic rotary machine 1 be N [rpm], then N / 60 [Hz] be the rotational frequency f0.

[0036] In this embodiment, when the capacity of the hydraulic rotating machinery 1 is maintained at a predetermined value α greater than the minimum value, the processing circuit 73 performs frequency analysis on the measurement result of the first pressure gauge 71, i.e., the pressure waveform, to generate a spectrum. Therefore, even during the operation of engineering or industrial machinery, the pressure of the hydraulic rotating machinery 1 can be measured under the same conditions. For example, when the minimum value of the capacity of the hydraulic rotating machinery 1 is set to 0% and the maximum value of the capacity of the hydraulic rotating machinery 1 is set to 100%, the predetermined value α can be more than 50% and less than 100%, or it can be more than 70% and less than 100%.

[0037] In this embodiment, when the tilt command pressure measured by the second pressure gauge 72 is at its maximum, the processing circuit 73 performs frequency analysis on the measurement result of the first pressure gauge 71, i.e., the pressure waveform, to generate a spectrum. For example, the processing circuit 73 can generate a spectrum whenever the tilt command pressure measured by the second pressure gauge becomes maximum. Alternatively, if the tilt command pressure measured by the second pressure gauge remains at its maximum for a long period, the processing circuit 73 can generate a spectrum at predetermined intervals. The measurement time of the pressure waveform used to generate the spectrum is, for example, 0.5 to 3 seconds.

[0038] Furthermore, the processing circuit 73 preferably performs frequency analysis on the measurement result of the first pressure gauge 71, i.e., the pressure waveform, to generate a spectrum when the capacity of the hydraulic rotating machinery 1 is maintained at a predetermined value α and the discharge pressure of the axial piston pump 1A of the hydraulic rotating machinery 1 is maintained at a predetermined value β. For example, the predetermined value β can be 1 MPa or more and 20 MPa or less, or it can be 1 MPa or more and 10 MPa or less.

[0039] The spectrum contains multiple rotational order components that are integer multiples of the rotational frequency f0. For example, the rotational order components include rotational first-order components f1 to rotational ninth-order components f9, which are 1 to 9 times the rotational frequency f0.

[0040] In the case where the hydraulic rotary machine 1 is an axial piston pump 1A as described in this embodiment, when the number of pistons 51 is M, the pressure amplitude of the M-order rotational component, which is M times the rotational frequency f0, will increase regardless of whether the hydraulic rotary machine 1 is malfunctioning. On the other hand, when the hydraulic rotary machine 1 is functioning normally, the pressure amplitude of rotational components smaller than the M-order rotational component will decrease. Figure 3 This is the spectrum when hydraulic rotating machinery 1 malfunctions.

[0041] The processing circuit 73 records the pressure amplitude of a specific order component among multiple rotational order components in the spectrum. In the case where the hydraulic rotary machinery 1 is an axial piston pump 1A, the specific order component is preferably smaller than the aforementioned rotational M-order component. In this embodiment, the processing circuit 73 records the pressure amplitude P1 of the rotational 1st order component f1.

[0042] Subsequently, the processing circuit 73 calculates the frequency of occurrence for each recorded value of the pressure amplitude P1, and generates a signal as follows: Figure 4 A to Figure 4 As shown in Figure C, a graph relating pressure amplitude and frequency is displayed on display 74, with the horizontal axis representing pressure amplitude and the vertical axis representing frequency. Figure 4 A represents the normal condition of the hydraulic rotating machinery. Figure 4 B indicates a situation where an abnormality occurs in the hydraulic rotating machinery. Figure 4 C represents the situation when the abnormal condition of the hydraulic rotating machinery deteriorates.

[0043] The frequency curve on the graph of pressure amplitude and frequency of occurrence varies depending on whether there is an abnormality in the hydraulic rotating machinery 1 and the degree of the abnormality. For example... Figure 4 As shown in Figure A, when the hydraulic rotating machinery 1 is operating normally, the frequency curve becomes a narrow, high-angled mountain shape; as... Figure 4 B and Figure 4 As shown in Figure C, when the hydraulic rotating machinery 1 malfunctions, the frequency curve becomes a mountain shape with a wide width and low height.

[0044] Therefore, the processing circuit 73 determines whether there is any abnormality in the hydraulic rotating machinery 1 based on the change in the frequency curve over time on a graph showing the pressure amplitude and frequency of occurrence. In this embodiment, the processing circuit 73 determines whether there is any abnormality in the hydraulic rotating machinery 1 by comparing the current frequency curve with the frequency curve at the initial stage of operation. Here, "initial stage of operation" refers to the first month or less after the engineering or industrial machinery equipped with the hydraulic rotating machinery 1 begins operation. However, the processing circuit 73 may also determine whether there is any abnormality in the hydraulic rotating machinery 1 by comparing the frequency curves before and after a predetermined period.

[0045] For example, the processing circuit 73 can determine that the hydraulic rotating machine 1 has malfunctioned when the height of the current frequency curve is lower than the height of the initial frequency curve. Alternatively, the processing circuit 73 can also determine that the hydraulic rotating machine 1 has malfunctioned when the width of the current frequency curve is wider than the width of the initial frequency curve. Alternatively, the processing circuit 73 can also determine whether the hydraulic rotating machine 1 has malfunctioned based on the similarity between the current frequency curve and the initial frequency curve.

[0046] As explained above, in the anomaly detection system 7 of this embodiment, the processing circuit 73 statistically determines whether the hydraulic rotating machinery 1 has any anomalies based on multiple measurement results. Furthermore, the frequency curve used to determine whether an anomaly exists varies depending on whether the hydraulic rotating machinery 1 has an anomaly and the degree of the anomaly. Therefore, by performing a determination based on the change of the frequency curve over time, it is possible to accurately determine whether the hydraulic rotating machinery 1 has any anomalies.

[0047] Furthermore, in this embodiment, the processing circuit 73 compares the current frequency curve with the frequency curve at the initial stage of installation. The effects of individual differences in the hydraulic rotating machinery 1, as well as the noise specific to the engineering or industrial machinery equipped with the hydraulic rotating machinery 1, are included in both the initial frequency curve and the current frequency curve. Therefore, by comparing the current frequency curve with the initial frequency curve, these effects can be offset.

[0048] Furthermore, since the processing circuit 73 displays a graph on the display 74 showing the pressure amplitude and frequency of occurrence, the person viewing the graph can visually determine whether the hydraulic rotating machinery 1 is normal or abnormal.

[0049] <Second Implementation Method> Next, the anomaly detection system of the hydraulic rotating machinery 1 according to the second embodiment will be described. The only difference between the anomaly detection system of this embodiment and the anomaly detection system 7 of the first embodiment is the determination method of the processing circuit 73.

[0050] Similar to the first embodiment, firstly, the processing circuit 73 performs frequency analysis on the multiple measurement results of the first pressure gauge 71, i.e., the pressure waveform, and generates... Figure 3 The spectrum shown.

[0051] In this embodiment, the processing circuit 73, similarly to the first embodiment, performs frequency analysis on the measurement result of the first pressure gauge 71, i.e., the pressure waveform, to generate a spectrum when the capacity of the hydraulic rotating machinery 1 is maintained at a predetermined value α greater than the minimum value. Therefore, even during the operation of engineering or industrial machinery, the pressure of the hydraulic rotating machinery 1 can be measured under the same conditions. For example, when the minimum value of the capacity of the hydraulic rotating machinery 1 is set to 0% and the maximum value of the capacity of the hydraulic rotating machinery 1 is set to 100%, the predetermined value α can be more than 50% and less than 100%, or it can be more than 70% and less than 100%.

[0052] In this embodiment, when the tilt command pressure measured by the second pressure gauge 72 is at its maximum, the processing circuit 73 performs frequency analysis on the measurement result of the first pressure gauge 71, i.e., the pressure waveform, to generate a spectrum. For example, the processing circuit 73 can generate a spectrum whenever the tilt command pressure measured by the second pressure gauge becomes maximum. Alternatively, if the tilt command pressure measured by the second pressure gauge remains at its maximum for a long period, the processing circuit 73 can generate a spectrum at predetermined intervals. The measurement time of the pressure waveform used to generate the spectrum is, for example, 0.5 to 3 seconds.

[0053] Furthermore, the processing circuit 73 preferably performs frequency analysis on the measurement result of the first pressure gauge 71, i.e., the pressure waveform, to generate a spectrum when the capacity of the hydraulic rotating machinery 1 is maintained at a predetermined value α and the discharge pressure of the axial piston pump 1A of the hydraulic rotating machinery 1 is maintained at a predetermined value β. For example, the predetermined value β can be 1 MPa or more and 30 MPa or less, or it can be 1 MPa or more and 10 MPa or less.

[0054] The processing circuit 73 records the pressure amplitude of a specific order component among multiple rotational order components in the spectrum. In the case where the hydraulic rotary machinery 1 is an axial piston pump 1A, the specific order component is preferably smaller than the aforementioned rotational M-order component. In this embodiment, the processing circuit 73 records the pressure amplitude P1 of the rotational 1st order component f1.

[0055] Subsequently, the processing circuit 73 uses at least one of the recorded average value Pa of the pressure amplitude P1 and the dispersion S as an index value, and determines whether there is any abnormality in the hydraulic rotating machinery 1 based on the change of the index value over time. In this embodiment, the processing circuit 73 determines whether there is any abnormality in the hydraulic rotating machinery 1 by comparing the current index value with the index value at the initial stage of installation. Here, "initial stage of installation" refers to the first month after the start of operation of the engineering or industrial machinery equipped with the hydraulic rotating machinery 1. However, the processing circuit 73 may also determine whether there is any abnormality in the hydraulic rotating machinery 1 by comparing the index values ​​before and after a predetermined period.

[0056] Both the average value Pa of the pressure amplitude P1 and the dispersion S vary depending on whether there is an abnormality in the hydraulic rotating machinery 1 and the degree of the abnormality. For example... Figure 4 As shown in Figure A, the average value Pa decreases when the hydraulic rotating machinery 1 is operating normally; as Figure 4 B and Figure 4 As shown in C, it increases when the hydraulic rotating machinery 1 malfunctions. On the other hand, as... Figure 4 As shown in A, the dispersion S decreases when the hydraulic rotating machinery 1 is operating normally; as... Figure 4 B and Figure 4 As shown in C, it increases when the hydraulic rotating machinery 1 malfunctions. Furthermore, the dispersion S can be either variance or standard deviation.

[0057] For example, the processing circuit 73 can determine that the hydraulic rotating machine 1 has malfunctioned when the average value Pa of the current pressure amplitude P1 is higher than the average value Pa of the pressure amplitude P1 at the initial stage of installation by a predetermined value. Alternatively, the processing circuit 73 can determine that the hydraulic rotating machine 1 has malfunctioned when the dispersion S of the current pressure amplitude P1 is higher than the dispersion S of the pressure amplitude P1 at the initial stage of installation by a predetermined value. Furthermore, the processing circuit 73 can also combine both conditions to make a determination.

[0058] Alternatively, the processing circuit 73 can also determine whether there is any abnormality in the hydraulic rotating machinery 1 based on the amount or rate of change of the index value before and after the predetermined period. For example, when the index value before the predetermined period is set as A and the index value after the predetermined period is set as B, the amount of change is BA and the rate of change is (BA) / A.

[0059] As explained above, in the anomaly detection system 7 of this embodiment, the processing circuit 73 statistically determines whether the hydraulic rotating machinery 1 has any anomalies based on multiple measurement results. Furthermore, the index value used to determine whether an anomaly exists (i.e., at least one of the average value Pa of the pressure amplitude P1 and the dispersion S) varies depending on whether the hydraulic rotating machinery 1 has an anomaly and the degree of the anomaly. Therefore, by performing a determination based on the change of the index value over time, it is possible to accurately determine whether the hydraulic rotating machinery 1 has any anomalies.

[0060] Furthermore, in this embodiment, the processing circuit 73 compares the current index value with the index value at the initial stage of installation. The influence of individual differences in the hydraulic rotating machinery 1, as well as the influence of noise specific to the engineering or industrial machinery equipped with the hydraulic rotating machinery 1, are included in both the index value at the initial stage of installation and the current index value. Therefore, by comparing the current index value with the index value at the initial stage of installation, these influences can be offset.

[0061] The processing circuit 73 can also, similarly to the first embodiment, calculate the frequency of occurrence for each recorded value of pressure amplitude P1, create a graph of pressure amplitude versus frequency of occurrence, and display it on the display 74. In this case, a person viewing the graph can visually determine whether the hydraulic rotating machinery 1 is normal or abnormal.

[0062] <Other Implementation Methods> This disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of this disclosure.

[0063] For example, in either the first or second embodiment, when generating the spectrum, the processing circuit 73 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 required.

[0064] The first pressure gauge 71 can also measure the discharge pressure of the axial piston pump 1A as the pressure of the hydraulic rotating machinery 1. Even in this case, if the processing circuit 73 performs the same processing as in the described embodiment, it can accurately determine whether there is any abnormality in the hydraulic rotating machinery 1.

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

[0066] Furthermore, the hydraulic rotating machinery 1 can also be a hydraulic motor other than an axial piston motor. In the case where the hydraulic rotating machinery 1 is an axial piston motor or a hydraulic motor other than an axial piston motor, the first pressure gauge 71 can measure both the drain pressure and the inflow pressure.

[0067] Summary As a first aspect, this disclosure provides an anomaly detection system for hydraulic rotating machinery, comprising: a pressure gauge for measuring pressure with respect to the hydraulic rotating machinery; and a processing circuit that performs frequency analysis on multiple pressure gauge measurements, i.e., pressure waveforms, to generate a spectrum, records the pressure amplitude of specific order components in the spectrum that are integer multiples of the rotation frequency, calculates the occurrence frequency for each recorded pressure amplitude value, and determines whether the hydraulic rotating machinery has an anomaly based on the change of the frequency curve over time on a graph of the pressure amplitude and the occurrence frequency.

[0068] Based on the above configuration, the processing circuit statistically determines whether the hydraulic rotating machinery has any abnormalities using multiple measurement results. Furthermore, the frequency curve used to determine whether an abnormality exists varies depending on whether the hydraulic rotating machinery has an abnormality and the degree of the abnormality. Therefore, by performing a determination based on the change of the frequency curve over time, it is possible to accurately determine whether the hydraulic rotating machinery has any abnormalities.

[0069] In the second embodiment, as in the first embodiment, the hydraulic rotating machinery is mounted on engineering or industrial machinery. The processing circuit can determine whether the hydraulic rotating machinery has any abnormalities by comparing the current frequency curve with the frequency curve at the initial stage of mounting. The influence of individual differences in the hydraulic rotating machinery, as well as the influence of noise specific to the engineering or industrial machinery mounting the hydraulic rotating machinery, are included in both the initial frequency curve and the current frequency curve. Therefore, by comparing the current frequency curve with the initial frequency curve, these influences can be offset.

[0070] As a third embodiment, in the first or second embodiment, the processing circuit can display a graph on the display showing the relationship between the pressure amplitude and the frequency of occurrence. The frequency curve appears as a narrow, high-angle ridge when the hydraulic rotating machinery is functioning normally, and as a wide, low-angle ridge when the hydraulic rotating machinery is malfunctioning. Therefore, if a graph containing the frequency curve is displayed on the display, the viewer can visually determine whether the hydraulic rotating machinery is functioning normally or malfunctioning.

[0071] As a fourth aspect, this disclosure provides an anomaly detection system for hydraulic rotating machinery from a second aspect, comprising: a pressure gauge that measures pressure with respect to the hydraulic rotating machinery; and a processing circuit that performs frequency analysis on multiple pressure gauge measurements, i.e., pressure waveforms, to generate a spectrum, records the pressure amplitude of a specific order component in the spectrum that is an integer multiple of the rotation frequency, uses at least one of the average value of the recorded pressure amplitude and the dispersion as an index value, and determines whether the hydraulic rotating machinery has an anomaly based on the change of the index value over time.

[0072] Based on the above configuration, the processing circuit statistically determines whether the hydraulic rotating machinery is malfunctioning using multiple measurement results. Furthermore, the index value used to determine whether malfunctioning is present (i.e., at least one of the average pressure amplitude and its dispersion) varies depending on whether the hydraulic rotating machinery is malfunctioning and the degree of malfunction. Therefore, by performing a determination based on the change of the index value over time, it is possible to accurately determine whether the hydraulic rotating machinery is malfunctioning.

[0073] As a fifth form, in the fourth form, the hydraulic rotating machinery is mounted on engineering or industrial machinery. The processing circuit can determine whether the hydraulic rotating machinery has any abnormalities by comparing the current indicator value with the indicator value at the initial stage of mounting. The influence of individual differences in the hydraulic rotating machinery, as well as the influence of noise specific to the engineering or industrial machinery mounting the hydraulic rotating machinery, are included in both the initial and current indicator values. Therefore, by comparing the current indicator value with the initial indicator value, these influences can be offset.

[0074] As a sixth embodiment, in the fourth or fifth embodiment, the processing circuit can calculate the occurrence frequency for each recorded pressure amplitude value and display a graph on the display showing the relationship between the pressure amplitude and the occurrence frequency. The frequency curve appears as a narrow, high-angle ridge when the hydraulic rotating machinery is functioning normally, and as a wide, low-angle ridge when the hydraulic rotating machinery is malfunctioning. Therefore, if a graph containing the frequency curve is displayed on the screen, the viewer can visually determine whether the hydraulic rotating machinery is functioning normally or malfunctioning.

[0075] As a seventh form, in any of the first to sixth forms, for example, the hydraulic rotary machinery may also be an axial piston pump or an axial piston motor.

[0076] As the eighth embodiment, in any of the first to seventh embodiments, the hydraulic rotating machinery is a variable-capacity axial piston pump mounted on construction or industrial machinery and forming the hydraulic circuit of the construction or industrial machinery together with at least one hydraulic actuator. The capacity of the hydraulic rotating machinery is changed by a regulator, and the processing circuit can perform frequency analysis on the measurement result of the first pressure gauge, i.e., the pressure waveform, to generate a spectrum when the capacity of the hydraulic rotating machinery is maintained at a predetermined value greater than the minimum value. According to this configuration, even during the operation of construction or industrial machinery, the pressure with respect to the hydraulic rotating machinery can be measured under the same conditions.

[0077] As a ninth form, in the eighth form, for example, when the minimum value of the capacity of the hydraulic rotating machinery is set to 0% and the maximum value of the capacity of the hydraulic rotating machinery is set to 100%, the predetermined value can be more than 50% and less than 100%.

Claims

1. An anomaly detection system for hydraulic rotating machinery, comprising: A pressure gauge that measures pressure with respect to hydraulic rotating machinery; as well as The processing circuit performs frequency analysis on the pressure waveforms measured by the pressure gauge multiple times to generate a spectrum, records the pressure amplitude of specific order components in the spectrum that are integer multiples of the rotation frequency, calculates the occurrence frequency for each recorded pressure amplitude value, and determines whether there is any abnormality in the hydraulic rotating machinery based on the change of the frequency curve over time on a graph of the pressure amplitude and the occurrence frequency.

2. The anomaly detection system for hydraulic rotating machinery according to claim 1, wherein, The hydraulic rotary machinery is mounted on engineering machinery or industrial machinery. The processing circuit determines whether the hydraulic rotating machinery has any abnormalities by comparing the current frequency curve with the frequency curve at the beginning of the installation.

3. The anomaly detection system for hydraulic rotating machinery according to claim 1 or 2, wherein, The processing circuit displays a graph on the display showing the relationship between the pressure amplitude and the frequency of occurrence.

4. An anomaly detection system for hydraulic rotating machinery, comprising: A pressure gauge that measures pressure with respect to hydraulic rotating machinery; as well as The processing circuit performs frequency analysis on the pressure waveforms measured by the pressure gauge multiple times to generate a spectrum, records the pressure amplitude of a specific order component in the spectrum that is an integer multiple of the rotation frequency, takes at least one of the average value and dispersion of the recorded pressure amplitude as an index value, and determines whether the hydraulic rotating machinery has any abnormalities based on the change of the index value over time.

5. The anomaly detection system for hydraulic rotating machinery according to claim 4, wherein, The hydraulic rotary machinery is mounted on engineering machinery or industrial machinery. The processing circuit determines whether the hydraulic rotating machinery has any abnormalities by comparing the current index value with the index value at the beginning of the installation.

6. The anomaly detection system for hydraulic rotating machinery according to claim 4 or 5, wherein, The processing circuit calculates the occurrence frequency for each recorded pressure amplitude value and displays a graph of the pressure amplitude versus the occurrence frequency on a display.

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

8. The anomaly detection system for hydraulic rotating machinery according to any one of claims 1, 2, 4, and 5, wherein, The hydraulic rotary machinery is a variable-capacity axial piston pump mounted on engineering or industrial machinery and forming the hydraulic circuit of the engineering or industrial machinery together with at least one hydraulic actuator. The capacity of the hydraulic rotary machinery is changed by a regulator. When the capacity of the hydraulic rotary machinery is maintained at a predetermined value greater than the minimum value, the processing circuit performs frequency analysis on the measurement result of the first pressure gauge, i.e., the pressure waveform, to generate a spectrum.

9. The abnormality detection system for hydraulic rotating machinery according to claim 8, wherein, When the minimum capacity of the hydraulic rotating machinery is set to 0% and the maximum capacity of the hydraulic rotating machinery is set to 100%, the predetermined value is above 50% and below 100%.

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